RESEARCH ON METHOD FOR GEODETIC MONITORING, ANALYZING FOUNDATION AND BASEMENT DEFORMATION OF HIGH RISE BUILDINGS IN THE CONSTRUCTION PERIOD

MINISTRY OF EDUCATION AND TRAINING
HANOI UNIVERSITY OF MINING AND GEOLOGY







TRAN NGOC DONG



RESEARCH ON METHOD FOR GEODETIC MONITORING,
ANALYZING FOUNDATION AND BASEMENT DEFORMATION OF
HIGH-RISE BUILDINGS IN THE CONSTRUCTION PERIOD



Study field: Geodesy and mapping
Code: 62520503






SUMMARY OF ENGINEERING DOCTORAL DISSERTATION

Hanoi - 2014

The dissertation has been completed at the Department of
Engineering surveying, of Surveying Faculty, Hanoi University of
Mining and Geology


Scientific Supervisors: Assoc. Prof. Dr. Tran Khanh
Hanoi university of Mining and Geology


Examiner 1: Dr. Duong Chi Cong
VietNam Institute of Geodesy and cartography

Examiner 2: Dr. Nguyen Van Van
Association of Geodesy, Maps and Remote Sensing of Vietnam

Examiner 3: Dr. Vu Van Dong
Defense Mapping Agency of VietNam - General Staff


The dissertation will be defended at the University examination
Council at the Hanoi University of Mining and Geology, at… h,
……………… 2014

This dissertation can be referenced at the National library or at the library
of the Hanoi University of Mining and Geology.
1

INTRODUCTION

1. The importance of dissertation
Recently, when excavating holes for constructing the foundation and basement
of a high-rise building, many adjacent works have confronted heavy breakdowns,
which caused many economic losses and concern in society. Those weaknesses are
mainly caused by monitoring and analyzing impacts that are not conducted in time of
the process of constructing the foundation and basement.
The issue on monitoring, analyzing the deformation of foundation and basement
of a high-rise building in the construction period becomes urgent. However, until
now, this issue has not been paid crucial attention to. There has not had any careful,
comprehensive research and proposed technical solution. Thus, researching the
method of monitoring, analyzing foundation and basement deformation of a high-rise
building in the construction period is very necessary. This contributes to ensuring safety
for not only the entire building but also adjacent buildings, people and normal activities
of the residents.
2. Purpose, object and scope of research
- The dissertation aims at contributing to developing and finalizing the method of
monitoring, analyzing deformation, evaluating and modeling the displacement process
of the foundation and basement of the high-rise building in the construction period.
- Object of research is: the method of monitoring, analyzing deformation of
foundation and basement of high-rise buildings in Vietnam.
- Scope of research of the dissertation consists of: Researching the method of
surveying, using sensing to monitor the deformation of foundation and basement of

the high-rise buildings; Researching the combination of method of surveying and
using sensing to increase the quality and effectiveness of monitoring the deformation
of the foundation and basement; Analyzing, evaluating and modeling the
displacement process of the foundation and diaphragm wall of the high-rise buildings
in the period of constructing the foundation and basement.
3. Contents of research
1- Researching the combination of method of surveying and using sensingto monitor
the settlement of the foundation and displacement of the diaphragm wall of the high-
rise buildings in the period of constructing the foundation and basement.
2- Researching the application of the automatic monitoring system for monitoring the
displacement of the diaphragm wall continuously.
3- Building the displacement model; Analyzing, evaluating and predicting the
displacement of the foundation and diaphragm wall of the high-rise buildings.
4- Developing the software for analyzing the deformation of the foundation and
basement of the high-rise buildings.
4. Method of research
Method of research consists of statistics, analysis, experiment, comparison,
informatics application and mathematical method.
5. Scientific and practical meaning of the Dissertation
Scientific meaning: The Dissertation contributes to developing and finalizing the
method of monitoring, analyzing deformation and modeling the displacement process
2

of the foundation and basement of high-rise buildings in the construction period.
Practical meaning: The research results of the Dissertation could be applied for
monitoring, analyzing, evaluating and predicting the foundation and basement of
high-rise buildings in the construction period and adjacent buildings.
6. Theoretical points to be defended
- First theoretical point: The solution in combining the surveying method and method
of using sensing as proposed in the Dissertation allows increasing the effectiveness of

monitoring the deformation of foundation and diaphragm wall of high-rise buildings.
- Second theoretical point: The work deformation model that is developed based on
the monitored data allows evaluating settlement as well as displacement of the
foundation and diaphragm wall of high-rise buildings chronologically, in space and
evaluating the dependence between deformation and its agent.
7. New points of the Dissertation
1- The Dissertation suggests the solution in combining the surveying method and
method of using sensing as proposed in the Dissertation allows increasing the
effectiveness of monitoring the deformation of foundation and diaphragm wall of
high-rise buildings.
2- The Dissertation suggests developing the models on displacement of the
foundation and diaphragm wall of high-rise buildings chronologically, in space and
evaluating the dependence between deformation and its agents.
3- The Dissertation suggests developing the software for analyzing foundation and
basement deformation of high-rise buildings.
8. Structure and contents of the Dissertation
Apart from Preface, Conclusion, the Dissertation is represented in five Chapters
with more than 130 pages of interpretations, figures and charts.

Chapter 1. OVERVIEW ABOUT MONITORING THE DEFORMATION OF
THE FOUNDATION AND BASEMENT OF HIGH-RISE BUILDINGS IN THE
CONSTRUCTION PERIOD
1.1. Overview of foreign research works
1 - Monitoring the displacement of the foundation of high-rise buildings in the
construction period of foundation and basement.
- Determining monitoring scope [82].
- Monitoring method: Surveying and using sensing [46], [47], [48], [49], [52], [53], [54].
2 - Analyzing and evaluating the results on monitoring the displacement of the
foundation and basement of the high-rise buildings [47], [50], [53], [60], [62].
3 – Automation of monitoring and processing data [51], [55], [57], [58], [61], [63].

1.2. Overview of domestic research works
1- Theoretical researches
- Researching the method and procedure of monitoring the work deformation [3], [4],
[5], [9], [13], [27], [28], [29].
- Researching network design and processing the work deformation monitoring data
[2], [10], [15], [19], [[20], [32].
- Researching application of modern devices into monitoring the work deformation
[3], [5], [32].
3

- Researching and analyzing the work deformation [18], [19], [29], [32].
- Researching the application of informatics into processing the work deformation
monitoring data [8], [21], [29].
2 - Deployment of monitoring the building foundation in reality
There have been research works [1] in monitoring the foundation of the high-rise
buildings. Some of these works have become the National Standards such as [34],
[35], [37], [38].
- Determining monitoring scope [36].
- Monitoring method: Surveying and using sensing.
1.3. General evaluation of the research situation
1 - In general, the researches on this field in the world have some points that have not
been suitable to the conditions in Vietnam (weak soil, mixed buildings, construction
elements, etc.).
2 - In Vietnam, the used modern devices and technologies are mainly imported.
Vietnam has not manufactured the specialized measurement devices for monitoring
the work deformation.
1.4. Weaknesses and research orientations in the Dissertation
At present, the method of surveying and using sensing for monitoring the
deformation of the foundation and basement of the high-rise buildings are still
separate from each other. Thus, research on combination of the surveying and sensor-

used method to increase the quality and effectiveness of monitoring the deformation
of the foundation of the high-rise buildings is necessary.
Researching the application of the automatic monitoring system into monitoring
the displacement of the diaphragm wall of the high-rise buildings continuously to
contribute to preventing the accidents that could occur in executing holes is necessary.
At present, the monitoring process in this period are just for data collection only
without specific analyses and evaluations of the effects of the hole excavating process
on the adjacent works. Therefore, it is necessary to research, analyze the monitoring
data and developing the model on displacement of the foundation and diaphragm wall
to control the accidents that could occur to the work and adjacent works.

Chapter 2. MONITORING THE SETTLEMENT OF THE FOUNDATION
AND BASEMENT OF THE HIGH-RISE BUILDINGS IN THE
CONTRUCTION PERIOD
2.1. Technical requirements on monitoring the settlement in the process of
building the foundation and basement of the high-rise buildings
2.1.1. Causes of settlement in the process of executing the foundation and basement
In the process of excavating holes for constructing the foundation and basement,
when some soil volume is taken, the stress status will be changed. This leads to
deformation of the soil block surrounding the excavated holes. Soil will displace to
the excavated holes. The displacement extent depends on the quality of the support
structure, soil type, distance as well as location and load of the adjacent work. The
combination of these displacements will make the ground surface adjacent to the
excavated holes settle. If this affected area has works, these works will be deformed.
4

2.1.2. Settlement monitoring contents in the foundation and basement construction
process
- To monitor settlement of the ground surface; to monitor settlement in line with
depth of soil layers surrounding the excavated holes.

- To monitor settlement of adjacent works.
- To monitor settlement of emerging of the foundation pit (ignite of the
excavated hole bottom).
- According to [35], measuring and determining the work settlement should be
performed immediately after the foundation is built completely. When constructing
the basement, the work has had load. Thus, it is necessary to monitor the settlement
of the work immediately in this period.
2.1.3. Determination of the settlement monitoring area in the foundation and
basement construction process
If the design does not indicate the area that should be monitored settlement, we
could calculate this affecting area using estimating formulas of the soil mechanics
theory. Accordingly, the affecting scope of the soil surrounding the excavated hole is
estimated by formula [80]:
o
o
B = H . tg(45 - / 2 )
(2.1)
In which: B
o
- Settlement effect scale of the soil block (m); H - Depth of the
diaphragm wall structure (m); φ - Angle of internal friction of soil (
o
).
2.1.4. Requirements on accuracy and settlement monitoring cycle in the foundation
and settlement construction process
2.1.4.1. Requirements on accuracy in settlement monitoring
Method 1: To base on the predicted settlement value (provided by the designing
unit) to determine the requirement on monitoring accuracy.
Method 2. It is possible to use the settlement measurement grades in Vietnamese
Standard 9360:2012 [35] to monitor the settlement of the foundation of the high-rise

buildings. Under this Standard, measuring the settlement is divided into three levels:
level I, level II and level III.
2.1.4.2. Settlement monitoring cycle
Settlement monitoring cycle in the foundation and basement construction
process is determined based on the construction progress.
2.2. Monitoring the settlement of the foundation of the high-rise buildings in the
foundation and basement construction period by the surveying method
2.2.1. Structure of landmark for monitoring the settlement of the foundation and
basement of the high-rise buildings
2.2.2. Designing the monitoring network system
The system of settlement monitoring height network is designed with two levels:
basic height network and monitoring network.
2.2.3. Monitoring settlement of the ground base surrouding the foundaiton pit
Height of the point of monitoring the settlement of the ground base surrounding
the foundation pit should be measured by the high geometric measurement method
with accuracy in accordance with settlement measure level III.
5

2.2.4. Monitoring settlement of the works adjacent to the excavated holes
Measuring the settlement of the adjacent works (residents’ houses,
steel-enforced concrete works) should be conducted with accuracy in
accordance with settlement measure level II.
2.2.5. Monitoring emerging of the foundation pit
Height of the point of monitoring the emerging deformation of the foundation
pit should be measured by the high geometric measurement method with accuracy in
accordance with settlement measure level III.
2.2.6. Monitoring the settlement of the main work in the basement construction process
In nature, monitoring the settlement of the main work means monitoring the
settlement of the diaphragm wall (basement wall) and internal parts of the diaphragm
wall (column, partition, lifter wall, etc.). Accuracy in measuring the settlement of the

main work should follow the accuracy of measuring the settlement level II.
2.2.7. Processing the settlement monitoring data of the foundation of the high-rise
buildings in the foundation and basement construction period
2.2.7.1. Analysis of stability of basic height mark
Standard on stability of basic height mark:
S
i
2
m
| S | t.
1k

(2.15)
In formula (2.15): S
i
- settlement of the basic height point in the current cycle in
comparison with the first cycle; m
S
- requirement on accuracy in settlement
determination; ; t: coefficient for determining and correcting limit error (t = 2÷3); k -
accuracy attenuation coefficient between network levels (k = 2÷3).
2.2.7.2. Calculation of adjustment of the settlement monitoring height network
2.2.7.3. Calculation of work settlement parameter
2.2.8. Comment on monitoring the settlement of the foundation of the high-rise
buildings by the surveying method
The surveying method has the advantage of high accuracy, giving absolute
settlement value. The disadvantage of this method is that in order to monitor
settlement of the soil layers in line with their depths (monitoring settlements of the
foundation soil layers), it is required to execute separate monitoring marks. Thus, the
installation takes huge effort and each depth needs to be monitored requires a

separate boring hole for installing mark.
2.3. Monitoring the settlement of the foundation of high-rise buildings in the
construction period using sensing
2.3.1. Structure of magnetic extensometer system
Magnetic extensometer is a specialized device for monitoring settlement in
compliance with the magnetic induction principle. The magnetic extensometer system
consists of: guide pipe, standard magnet, spider magnet, plate magnet, meter wire and
magnetic probe.
6
















Figure 2.9. Measuring settlement by magnetic
extensometer
P O O P
H = H + L - L
(2.18)

In which: H
P
: Height of P; H
o
Height of bottom mark (benchmark height); L
o
:
Distance between pipe top and bottom mark; L
P
: Distance from pipe top to the
monitoring point P.
The settlement value of the monitoring point is determined by comparising its
heights in two various measurement cycles.
2.3.4. Accuracy in measuring settlement by magnetic extensometer method
According to Document [14], settlement square error is determined by magnetic
extensometer technology achieving size (5 8) mm.
2.3.5. Example on measuring settlement of the work foundation by magnetic
extensometer
2.3.6. Comment on monitoring settlement of the foundation of high-rise buildings
by sensing
The method of using sensing (magnetic extensometer) has the advantage that it
permits arranging many monitoring marks for various depths at each boring hole. The
disadvantage of this method is that it takes the point at the pipe bottom as benchmark.
Thus, it is required that the bottom of the guide pipe to be anchored into stable rock
layer lying at depth (not be settled). If this rock layer locates too deeply, it will be
difficult for installing and it is not economical for boring deeply. On the other hand, it
is impossible to evaluate the stability of the reference point in each monitoring cycle.
Therefore, if the reference point is settled, then the settlement value obtained at the
settlement measuring table will not reflect the settlement of the monitored soil layers
accurately.

2.4. Solution in combining the method of surveying and using sensing for
monitoring the settlement of the foundation of high-rise buildings
To overcome the disadvantage of the method of surveying and using sensing,
this Dissertation suggests combining these two methods together to monitor the
2.3.2. Installation method
Guide pipe with spider is
installed in boring hole and
arranged in sequence as shown in
Figure 2.9.
2.3.3. Principle on measuring
settlement by magnetic
extensometer
In magnetic extensometer
method, point at the pipe bottom
is taken as benchmark and height
of the monitoring point is
determined as follows (Figure 2.9)



. . . . . .
. .
. . . . . .
. . . .
. . . . . .
. . . . . .
. . . .
. . . . . .
. . . . . .
. . . .

. . . . . .
. . . . . .
. . . .
. . . . . .
. . . . . .
. . . .
. . . . . .
. . . . . .
. . . .
. . . . . .
Magnetic probe
Plate magnet
Spider magnet
Datum magnet
Filling soil
Original rock

L
0

L
P

A
P
1

O
P
n

P
i

Meter wire
7

settlement of the soil layers and emerging of the foundation pit. The combining
process is executed as follows:
2.4.1. Bottom of the guide pipe is anchored into a stable rock layer
Closing error of monitoring settlement by magnetic extensometer ( ) is
calculated by the following formula:
Δ
§T T§
= S - S
(2.19)
In formula (2.19): S
ĐT
- settlement of pipe top (Point A - Figure 2.9) measured by
magnetic extensometer; S
TĐ
- settlement of pipe top measured by surveying method.
Distributing the closing error ( ) for the measuring points at the depth in line
with the principle of direct proportion to the distance from the pipe bottom to the
measuring point will be able to determine the settlement values at the settlement
measuring tables with increased accuracy (formula 2.20).
Δ
i
ii
OP

§T
PP
OA
.L
S = S -
L
(2.20)
In which:
i
§T
P
S
: settlement of Poin P
i
measured by magnetic extensometer;
i
OP
L
:
distance from the point at the pipe bottom to the monitoring point P
i
;
OA
L
: distance
from the point at the pipe bottom to the monitoring point A at the pipe top.
2.4.2. Bottom of the guide pipe is anchored into an unstable rock layer
For this case, the value ( ) that is obtained using formula (2.19) could be
considered as the settlement of the reference point at the pipe bottom. At that time,
adjust the value ( ) for the measuring points at the depth by following formula:

Δ
ii
§T
PP
S = S -
(2.21)
Also in this case, it is possible to use the point at the top of tube as a reference
point. Elevation of the reference point is determined by surveying method (often,
geometric leveling).
2.4.3. Example on measuring the foundation settlement by the method of surveying
and magnetic extensometer
2.4.3.1. Example in case bottom of the guide pipe is anchored into a stable rock layer
2.4.3.2. Example in case bottom of the guide pipe is anchored into an unstable rock layer
2.4.4. Comments on monitoring settlement of the foundation of high-rise buildings by
combing the method of surveying and using sensing
The solution in combining the method of surveying and using sensing (magnetic
extensometer) for monitoring the settlement of the foundation of high-rise buildings
have the following meanings:
- To increase the accuracy in measuring settlement at the settlement monitoring
tables (in case bottom of the guide pipe is anchored into a stable rock layer)
- To permit taking the point at the pipe top as benchmark for determining
settlement at the settlement monitoring tables. So, in this case, the guide pipe should
not be anchored into the stable rock layer; it is only necessary to install the guide pipe
to the depth of the soil layer that needs monitoring settlement. Thus, it will be more
convenient for constructing and installing the guide pipe, allowing increasing the
effectiveness of monitoring the settlement of the foundation of high-rise buildings.
8

Chapter 3. MONITORING DISPLACEMENT OF THE DIAPHRAGM WAL
OF THE HIGH-RISE BUILDINGS IN THE FOUNDATION AND BASEMENT

CONSTRUCTION PERIOD
3.1. Technical requirements on monitoring displacement of the diaphragm wall
of high-rise buildings
3.1.1. Some general concepts of constructing the foundation and basement of
high-rise buildings
3.1.1.1. Measures in constructing the basement of high-rise buildings
3.1.1.2. Measures in obstructing soil for excavating hole in the foundation and
basement construction process
3.1.1.3. Diaphragm wall of high-rise buildings
3.1.2. Causes of displacement and deformation of the diaphragm wall
In the process of excavating holes for constructing the foundation and basement,
when some soil volume is taken, the stress status will be changed. This leads to
deformation of the soil block surrounding the excavated holes. Soil will displace to
the excavated holes, which could make the diaphragm wall displace.
3.1.3. Purpose of monitoring displacement of the diaphragm wall
Monitoring displacement of the diaphragm wall is aimed at determining
displacement and deformation extent; researching to find the cause of displacement
and deformation of the diaphragm wall; thereby, taking the measure for treating,
preventing the accident occurring to the work and adjacent works.
3.1.4. Requirements on accuracy and cycle of monitoring displacement of the
diaphragm wall
3.1.4.1. Requirement on monitoring accuracy
Method 1: Based on the predicted displacement value (provided by the
designing unit) to determine the requirement on monitoring accuracy.
Method 2: It is possible to use the displacement measurement levels in
Vietnamese Standard TCVN 9399:2012 “Buildings and civil structures - Measuring
horizontal displacement by surveying method” [38] to monitor the displacement of
diaphragm wall.
3.1.4.2. Cycle of monitoring displacement of the diaphragm wall
Monitoring cycle depends on the construction progress of the excavated hole.

3.2. Monitoring displacement of the diaphragm wall by the surveying method
3.2.1. Designing structure and distributing benchmark for monitoring
displacement of the diaphragm wall
3.2.2. Designing the network system for monitoring displacement of the diaphragm
wall
The system of monitoring displacement network of the diaphragm wall is
designed with two levels: basic and monitoring level. The requirement on errors in
determining the placement for the network levels is determined by the following
formulas:
- For basic network:

CS
q
q
2
m
m =
1k
(3.3)
9

- For monitoring network:

QT
q
q
2
k.m
m =
1k

(3.4)
In formulas (3.3) and (3.4): m
q
- required accuracy for displacement monitoring; k -
accuracy decrease coefficient between two network levels ( k = 2÷3).
3.2.3. Monitoring displacement of the diaphragm wall by angle-side measuring network
3.2.3.1. Triangle method
3.2.3.2. Polygon method
3.2.3.3. Synodic method
3.2.4. Monitoring displacement of the diaphragm wall by the standard method
3.2.5. Monitoring displacement of the diaphragm wall by the automatic monitoring
system
3.2.5.1. Introduction of the automatic monitoring system
3.2.5.2. Automatic monitoring of displacement of the diaphragm wall by Total Station
3.2.5.3. Software for processing the monitoring data automatically
3.2.6. Processing the data of monitoring displacement of the diaphragm wall
3.2.6.1. Analysis and evaluation of stabibility of the benchmarks in monitoring
displacement of the diaphragm wall
Like monitoring the settlement, the stability standard of the basic control point is:

q
i
2
m
q t.
1k

(3.7)
In formula (3.7): q
i

- displacement of the basic control point in the
current cycle in comparison with the first cycle; m
q
- requirement on accuracy in
displacement determination; t: coefficient for determining standard of limit error (t =
2÷3); k - accuracy attenuation coefficient between network levels (k = 2÷3).
3.2.6.2. Adjustment of the monitoring network
3.2.7. Calculation of displacement parameter of the diaphragm wall
3.2.7.1. Calculation of local displacement parameters
3.2.7.2. Graphic representation of displacement of the diaphragm wall
3.2.8. Proposal for processing the data of the automatic monitoring system when
monitoring more than one station
In nature, the automatic
monitoring method using Total
Station from one station is to measure
pole coordinate and does not have
residual measurement value.
Therefore, its reliability is not high
and could lead to mistake. To
increase the residual value of the
measurement value, it is necessary to
apply the surveying method from two
or more stations at the same time.

Figure 3.20. Graph on monitoring more than
one station automatically

A

3

y
O

x
B
P
S
1
α
1
S
2
α
2

1 2

C
S
3

α
3
10

To determine the most reliable coordinate of the monitoring points, it is
necessary to adjust the coordinates of the monitoring points. The process of
calculating and processing data is conducted as follows:
From Figure 3.20, the coordinates of the monitoring points are determined as
follows:
G 0 G
G 0 G
x x S.cos( ) x S.cos
y y S.sin( ) y S.sin
(3.14)
Deploying linearly expression (3:14) with approximate coordinates of
monitoring point x
(0)
, y
(0)
, obtain:
(0)
G
(0)
G
x - x
x cos - S.sin dS
x
y sin S.cos d
y - y

(3.16)
In (3.14) and (3.16): x
G,
y
G
- coordinates of the station points; dS, dβ - corrective
figures for measurement values S and β.
Symbol: K
xy
is the correlation matrix of coordinates of the monitoring points (x, y)
and K
Sα
is the correlation matrix of the measurement sides (S, β). At that time:

XY S
cos S.sin cos sin
K .K .
sin S.cos S.sin S.cos
(3.17)
with
2
S
S
2
m0
K
0m

Weight matrix of measurement values (x, y) is:

21
xy xy
P .K

(3.19)
Arithmetic equation on adjusting the coordinates of the measurement point is:

ii
ii
xx
yy
vl
1 0 x
x
v 0 1 y l
(i=1÷n) (3.21)
Pursuant to formula (3.21), apply the least squares principle to make and solve
the standard equations system to determine the corrective figures of coordinates for
the monitoring points and calculate the post-adjustment coordinates by following
formulas:

δ
δ
(0)
(0)
x = x + x
y = y + y
(3.27)
3.2.9 General comments on monitoring displacement of the diaphragm wall by the
surveying method

The surveying method has the advantages of giving high accuracy and absolute
displacement value. However, the basic disadvantage is that it is only convenient to
monitor the displacements of the points that are distributed at the top of the diaphragm
wall. Whereas, executing the foundation and basement of the high-rise buildings
requires monitoring the diaphragm wall in line with its depth in the whole process.
3.3. Monitoring displacement of the diaphragm wall using Inclinometer
3.3.1. Inclinometer structure
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Inclinometer is a specialized device for monitoring displacement in line with depth.
The structure of this device consists of four main components: guide pipe; probe;
signaling cable; reading device.
3.3.2. Principle on measuring the displacement using Inclinometer
Measuring the displacement using Inclinometer is to measure indirectly the
displacement of the object that need be monitored through the displacement of the
guide pipe (figure 3.22, 3.23).

Figure 3.22. Conventional directions in monitoring using Inclinometer



Figure 3.23. Calculation diagram on measuring displacement using Inclinometer
Calculation method in measuring displacement using Inclinometer is to take the
bottom of the measuring cylinder as basis for determining the displacements at the upper
measurement locations; thus, the bottom of the measuring cylinder must not be displaced.
On figure 3.23, lateral deviation for each measurement location by one axis is
determined by the following formula:
ii
d L.sin
(3.28)

In which: d
i
- lateral deviation between two adjacent measurement points by one
axis; L - measurement distance between two adjacent points;
θ
i
- angle of inclination
in comparison with vertical direction of i
th
point.
Lateral deviation value of any point by one axis is total measurement value
from the cylinder bottom to that point (figure 3.23); this value is called the
accumulative one (d) and calculated by following formula:
Axis A
Axis B
12

d = d
1
+ d
2
+ d
3
+…+ d
n
(3.32)
In which: d - lateral deviation of point n from the cylinder bottom (by one axis); d
i
-
lateral deviation of each point by one axis direction (i = 1 ÷ n).

Change in lateral deviation at each measurement distance in the monitoring
cycles shows that the guide pipe displaces. This displacement is calculated by taking
the present lateral deviation to deduct the initial lateral deviation.
3.3.3. Accuracy in measuring displacement using Inclinometer
Pursuant to the curriculum vitae of the devices provided by the producer, the
digital reader of Inclinometer now permits reading with the value displayed on the
screen to 0,01mm. Each time when the measurement probe moves 0,5m in the guide
pipe, it will read with error of 0,25mm. When the length of the guide pipe is 25m, the
accumulative error is 6mm [16], [86].
3.3.4. Monitoring displacement of the diaphragm wall using Inclinometer
3.3.4.1. Installation of the guide pipe
3.3.4.2. Monitoring sequences
3.3.4.3. Processing data and making the monitoring result report
3.3.5. General comments on monitoring displacement of the diaphragm wall using
Inclinometer
The method of using Inclinometer for monitoring the depth of the diaphragm
wall has the advantage of discovering displacements in accordance with depth.
However, the disadvantage of this method is that it could only discover relative
displacements of the diaphragm wall at various depths in comparison with one point
lying at depth (bottom of the diaphragm wall). If the point lying at depth is not stable,
the obtained monitoring value does not reflect the displacement of the diaphragm
wall accurately.
3.4. Solution in monitoring displacement of the diaphragm wall by combing the
method of surveying and using sensing
As represented above, the surveying method has the advantage of giving high
accuracy and absolute displacement value. However, the basic disadvantage of this
method is that it only permits monitoring displacements of the points distributed at
the top of the diaphragm wall.
The method of using Inclinometer has the advantage of discovering
displacements in accordance with depth. However, the disadvantage of this method is

that it could only discover relative displacements of the diaphragm wall at various
depths in comparison with one point lying at depth (bottom of the diaphragm wall). If
the point lying at depth is not stable, the obtained monitoring value does not reflect
the displacement of the diaphragm wall accurately.
To overcome the above disadvantages to determine the absolute displacement at the
depth locations of the diaphragm wall, this Dissertation suggests combining these two
methods to monitor displacement of the diaphragm wall. The combining process is
performed as follows:
13

3.4.1. Bottom of the guide pipe is anchored into an stable rock layer
In this case, monitoring
process is performed as follows: In
each cycle, apart from measuring
displacement in accordance with
depth using Inclinometer, the
center of the mouth of the guide
pipe is determined displacement by
the surveying method. From Figure
(3.27), could determine the
conversion formula between two
coordinate systems (from the

Figure 3.27. Coordinate system for
displacement measurement
surveying coordinate system to the Inclinometer coordinate system) for the center of
the mouth of the guide pipe by following formula (Figure 3.27):
T § ICL T § T §
T § ICL T § T §
(o) (o) (o)
X X Y
(o) (o) (o)
Y X Y
q q .cos - q .sin
q q .sin q .cos
(3.33)
In which:
T§
(o)
X
q
,
T§
(o)
Y
q
- displacement of the mouth pipe (Point O) measured by the
surveying method in the surveying coordinate system;
T§-ICL
(o)
X

q
,
T§-ICL
(o)
Y
q
- displacement
of the mouth pipe measured by the surveying method in the Inclinometer coordinate
system; - angle of rotation between two Inclinometer and surveying coordinate axis
systems (Figure 3.27) that could be determined by the surveying method or on
drawing.
Deviation values of the coordinate axes are calculated by following fomulas:
ICL T §-ICL
ICL T §-ICL
(o) (o) (o)
X X X
(o) (o) (o)
Y Y Y
q - q
q - q
(3.34)
In formula (3.34):
ICL
(o)
X
q
,
ICL
(o)
Y

q
- displacement of the pipe mouth measured by
Inclinometer in the Inclinometer coordinate system.
Distribution of the closing error for the measuring points in line with direct
proportion to the height of the monitoring point will determine the adjustment value
of the settlement values measured by Inclinometer:
X X X
ICL- T § ICL
YY
ICL- T § ICL
(i) (i) (o)
i
(i) (i) (o)
i
Y
H
q q -
H
H
q q -
H
(3.35)
In which:
X
ICL
(i)
q
,
Y
ICL

(i)
q
- displacements of Point i measured by Inclinometer at height
H
i
;
X
ICL-T§
(i)
q
,
X
ICL-T§
(i)
q
displacements of Point i measured by Inclinometer with adjusted
error; H
i
, H - height of monitoring point i and height of point at the pipe top in
comparison with point at the pipe bottom.
X
ICL
Y
TĐ
X
TĐ
T§
X
q
ICL

Y
q

ICL
X
q

α
Y
ICL
q
T§
Y
q

O

14

3.4.2. Bottom of the guide pipe is anchored into an unstable rock layer
As mentioned above, the measurement principle using Inclinometer is that the
displacement data is compared with the reference point at the bottom of the guide pipe.
When this point is not stable, the determined displacement level will not be accurate.
Thus, it is advised to select the reference point in measuring by Inclinometer to be the
point that could determine the location by the surveying method - that is the centers of
the mouths of the Inclinometer guide pipes on ground. The advantage is that the
measurement data processing software of Inclinometer provided by the manufacturer
enclosed with the device permits determining the displacements of the Inclinometer
measurement points in line with the reference point that is the mouth of the guide pipe.
Thus, in the calculation process using this software, it is necessary to relocate the

reference point of the Inclinometer measurement value as the point on the mouth of the
guide pipe. The obtained results are displacement values
ICL
(i)
X
q
,
ICL
(i)
Y
q
measured inside
the diaphragm wall. Although the points at the mouth of the guide pipe are not the
stable ones, their displacement level could be determined by the surveying method.
Thus, in each monitoring cycle, the center of the mouth of the Inclinometer guide pipe
must be located accurately in the surveying coordinate system and coordinate
difference between the main cycles as displacement values
T§
(o)
X
q
,
T§
(o)
Y
q
of the center of
the mouth of the guide pipe on ground.
Calculate to transfer the displacement value of the mouth of the guide pipe
measuring the surveying method to the Inclinometer coordinate system using formula

(3.33), obtain the displacements of the mouth of the guide pipe
T§-ICL
(o)
X
q
,
T§-ICL
(o)
Y
q
.
Deternining the coordinates by the surveying method has high accuracy. Thus,
the displacement level determined by the surveying method has higher reliability than
that determined by Inclinometer. Thus, it is possible to use the displacement value
measured by the surveying method to improve the displacement value measured by
Inclinometer. Symbol
T§-ICL
(o)
X
qx
,
T§-ICL
(o)
Y
qy
; use this value to improve each
measurement value
ICL
(i)
X

q
,
ICL
(i)
Y
q
in the relevant Inclinometer guide pipe by the
following formula:
XX
ICL- T § ICL
YY
ICL- T § ICL
(i) (i)
(i) (i)
q q x
q q y
(3.36)
3.4.3. Comments on monitoring the displacement of the diaphragm wall using the
method of surveying and using sensing
The solution in combining the method of surveying and using the sensing
mentioned above permits determining the absolute displacement of the monitoring
points at various depths of the diaphragm wall. In this solution, the bottom of the
guide pipe measured by Inclinometer does not need to be anchored into stable rock
layer. However, for monitoring the diaphragm wall, the guide pipe need be installed
equally to the depth of the diaphragm wall to obtain the monitoring data from the
bottom to the top of the diaphragm wall.
15

Chapter 4. ANALYSIS OF THE DEFORMATION OF THE FOUNDATION AND
BASEMENT OF HIGH-RISE BUILDINGS IN THE CONSTRUCTION PERIOD

4.1. Principles on developing the work displacement model by the monitoring data
When summarizing the work displacement in many cycles, we need analyze the
following issues:
1- General displacement trend of the work in space.
2 - General displacement trend of the work chronologically.
3- Evaluate dependence level of the work displacement level on some external elements
(Does work displacement depend on any element? If yes, determine mathematic expression).
To solve the above issues, it is necessary to develop the displacement model of
the work, which means describing the work displacement process by some
mathematical functions. In principle, the work displacement model is represented
through function No. [17]:
= F
1
(x) + F
2
(u) + F
3
(z) + w] (4.1)
In which: F
1
(x)- affecting part of a group of main elements that cause the work
displacement. Normally, only should develop the model using the main elements.
4.2. Model on foundation settlement and diaphragm wall displacement in space
4.2.1. Model on foundation settlement of high-rise buildings in the foundation and
basement construction period
4.2.1.1. Settlement model of solid foundation structure
For solid foundation structure, when the settlement monitoring points are
distributed in a wide range, use the plane equation to develop the settlement model.
This equation is as follows [17]:
i i i

S a.x b.y c
(4.2)
In which: x
i
, y
i,
S
i
are the coordinates in accordance with axis OX, OY and settlement
value of the monitoring point i; a, b, c: parameters of the settlement plane (parameters
permit determining the direction and biggest angle of inclination of the work).
In special case in which the monitoring points are distributed on one straight line
(or when it is necessary to develop the model in accordance with axes), we represent
settlement through the straight-line equation. The straight-line equation is as follows:
ii
S a.x b
(4.10)
In which: S
i
- settlement of point i (i=1÷n); x
i
- coordinate in the horizontal
direction of the monitoring point (i=1÷n); a, b - parameters of the straight line.
4.2.1.2. Settlement model of the foundation adjacent to the foundation pit
According to the soil mechanics theory, the settlement of foundation
surrounding the work is not even and forms cone of settlement. To represent the
overal settlement of the cone of settlement, it is possible to use parabolic function (for
example, quadratic unction)
Settlement model of the foundation at each time (cycle) has the form of general
parabolic function:

22
i 0 1 i 2 i 3 i 4 i i 5 i
S a a x a y a x b x y a y
(4.11)
To determine the parameters of the settlement model pursuant to (4.2), (4.10) và
(4.11) based on the monitoring dta (when the number of monitoring points is higher than
the number of parameters), the Dissertation has proposed the process and system of
16

formulas for determining the parameters in compliance with the least squares principle.
4.2.2. Displacement model of the diaphragm wall
4.2.2.1. Displacement model of the diaphragm wall in horizontal plane
Overal displacement of the
diaphragm wall may be
expressed through four
parameters: translational
transition at the central point of
the work (a
x
, a
y
), angle of
rotation ( ) and length
deformation coefficient (m) -
figure (4.4). The above
displacement parameters are
determined based on coordinate
conversion formula (4.13):

Figure 4.4. Transition between two coordinate
systems
X
Y
X' a X.m.cos( ) - Y.m.sin( )
Y' a Y.m.cos( ) X.m.sin( )
(4.13)
Symbol of transition parameter vector is Z; Z= (a
x
a
y
m)
T
. Note that the angle of
rotation has small value ( ≈ 0), deformation coefficient m ≈ 1, take z
(0)
= (0 0 0 1)
T
,
based on the monitoring data, we may make the system of corrective figure equations
for each measurement point as follows:
α

δ
ii
ii
x
xx
y
ii
y i i y
a
vq
a
1 0 -y x
=-
v 0 1 x y q
m
; (i=1÷n)
When the number of monitoring points is more than two, by applying the least
squares principle, we may determine the unknown vector
T
XY
z (a , a , , m)
.
Thereby, determine the transition parameters:
Z = Z
(0)
+ Z
4.2.2.2. Displacement model of the diaphragm wall in vertical plane
For the diaphragm wall that is monitored in accordance with depth, the
monitoring points are distributed closely to each other in one vertical plan. At that
time, we could develop the displacement model of the diaphragm wall in the vertical

plane. In this case, the displacement plan equation is as follows [27]:
i i i
q aX bH c
(4.25)
In which: X
i
, H
i
, q
i
- coordinates in accordance with axis OX, height and
displacement value of monitoring point i; a, b, c: parameters of the plane. When the
number of monitoring points is more than three, the parameters of the model are
determined in accordance with the least squares principle.
4.2.3. Application of adjustment analysis into evaluating the work deformation
Settlement model (4.2), (4.10) or transition model (4.13), (4.25) are developed
based on the assumptions that the work is absolutely solid (its deformation is not
Y'
a
Y
O
P
2
a
x

X’
X

O’

P1
Y
17

considerable). The error of this model is determined by the following formula:

2
MH
[V ]
m
nk

In which: n - the number of transition values; k- the number of model parameters.
Based on the model error value, it is possible to evaluate the deformation level of
the work. To execute this, we may use the adjustment analysis in accordance with the
Fisher verification standard, by making the ratio:
MH
0
2
2
m
F
m
(4.30)
with degree of freedom (n-k) and (n), in which: n - measurement value; k - the
number of parameters of the model.
In formula (4.30): m
MH
- model error; m
0

- mean square error of the displacement of
the monitoring points.
Comparison: if
gh
FF

(F
gh
- look up table), the work is not deformed; if
gh
FF
,
the work has deformation.
4.3. Chronological settlement and displacement model of the foundation of high-rise
buildings
4.3.1. Theoretical bases for predicting the chronological work displacement by the
monitoring data
It is assumed that the chronological work displacement model is represented
through the function in its general form:
q f(t)
(4.31)
Expand expression (4.31) linearly in accordance with variable zi with
approximate parameter vector
0 0 0 T
0 1 2 k
Z (z , z , , z )
, have:
0
i i1 1 i2 2 ik k i
q a dz a dz a dz q

; (i=1÷n) (4.33)
with coefficient a
ij
(j=1÷k) - function of the monitoring time.
0 0 0 0
i 1 1 2 2 k k
q a z a z a z
(4.34)
Function (4.31) with calculated parameters is the expression that represents the
chronological displacement model.
4.3.2. Application of adjustment analysis into evaluating reliability of the model
In case of developing the chronological displacement model, the selected model
is the prediction model; we have not known how the actual model is. Thus, in this
case, we could use the adjustment analysis to evaluate the stability of the model, in
accordance with the Fisher inspection standard, by making the ratio:
MH
0
2
2
m
F
m
(4.40)
with degrees of freedom (n-k) and (n), in which: n - the number of monitoring cycles
(excluding the first monitoring cycle); k - the number of parameters of the model. If F
≤ F
gh
, the selected model is appropriate.
18

4.3.3. Some chronological foundation settlement and displacement models of high-
rise buildings
4.3.3.1. Exponential function model
4.3.3.2. Polynomial function model
4.4. Evaluation of effects of the elements causing work displacement and
deformation
To evaluate the effects of the elements that cause work displacement and
deformation, we could use the simple linear correlation analysis method. The
performance process is as follows [17]:
4.4.1. Determination of correlation coefficient
It is assumed that we have
Xi, Yi i=1,n
- a two bidirectional contigency
obtained when monitoring random vector (X. Y), then sample correlation coefficient
XY
r
of X and Y is determined as follows:
i
XY
22
22
22
ii
(Xi - X)(Yi - Y)
XY - X Y
n
r
(Xi - X) (Yi - Y)
X - (X) Y - (Y)
nn

(4.43)
In which:
i
Xi
X =
n
;
i
Yi
Y =
n
;
i
XiYi
XY =
n
(4.44)
2
2
i
Xi
X =
n
;
2
2
i
Yi
Y =
n

(4.45)
To evaluate the reliability level of the correlation coefficient pursuant to the
number of monitoring times, use the following formulas:
1 - when n is big enough (n ≥ 50)
Calculate the standard deviation of the correlation coefficient by following
formula:
2
r
1- r

n
(4.46)
Correlation relationship between values X, Y is considered to be established if
the following condition is satisfied:
r
r3
(4.47)
2-When n < 50
When n<50, use the special function that is distributed in accordance with the
standard rule, called Fisher standard.
1 1+r
Z = ln
2 1-r
(4.48)
Adjustment of value Z is determined by the following formula:
19

σ
Z
1

n-3
(4.49)
In this case, the correlation relationship between values X, Y is also established with
the same condition like formula (4.47).
4.4.2. Development of regression function
When the correlation relationship between values X, Y has been established,
we will use the simple linear regression function to describe that relationship; the
regression function is as follows:
Y a.X b
(4.50)
Parameters a,b of the regression function is determined based on the least
squares principle or may be determined as follows:
2
2
XY
2
2
X - (X)
a r .
Y - (Y)
b Y - a.X
(4.53)
4.5. Analysis and evaluation of displacement of the adjacent works in the
foundation and basement construction process
4.5.1. Some criteria used for evaluating damages, accidents of the adjacent works
Angle deformation is used to evaluate damage of the available work close to the
excavated hole:

L
(4.59)

In which: - settlement difference at two points whose distance is L.
4.5.2. Evaluation of damage level of the adjacent work
The results on surveying, monitoring the excavated hole and work adjacent to
the excavated hole are used to grade the work damage in accordance with
deformation. Thereby, to suggest measures (designing and constructing) to manage
risks in constructing the foundation and basement of the high-rise buildings.
4.5.3. Control of risks and accidents of the work adjacent to the excavated hole
To ensure that the support structure of the excavated hole as well as its adjacent
work do not face accident, it is required to control the displacement of the excavated
hole by calculating and monitoring.
4.6. Development of the froundation and basement deformation analysis
software
4.6.1. Programming language
Language that is used for programming is Visual Basic.NET (VB.NET). The
developed software is called ADFB; this sofwate has the interface that helps the user
operate easily, calculate quickly and gives reliable result.
4.6.2. Brief design of the software
The designed software has the functions as shown in Table 4.3.

20

Table 4.3. Functions of ADFB software
File
Displacement
calculation
Displacement model
Displacement
analysis and
prediction
Help

Create
file

Settlement
- Settlement
parameter
- Graphic
settlement
representation
Settlement model
- By plane
- By parabol
- By straight-line
- Simple linear
correlation
analysis
- Function
model
displacement
prediction


Manual

Open
file
Displacement
- Displacement
parameter
- Displacement

graph
- Displacement
cross-section
Displacement model
- On horizontal plane
- On vertical plane
- By straight-line
Save
Save
As
Exit

Chapter 5. EXPERIMENT
5.1. Experiment in monitoring displacement of the diaphragm wall of high-rise
buildings in the foundation and basement construction period
5.1.1. Experiment in monitoring the displacement of the diaphragm wall of the
building by the automatic monitoring system
The experiment process was conduced for the diaphragm wall of a high-rise
building in Ba Dinh District - Ha Noi City. This building has two basements. The
method of excavating the hole for constructing the foundation and basement is to
excavate openly; the support for the wall of the excavated hole is the diaphragm wall
that is anchored in soil.
The system that is used to monitor the continuous displacements of the
diaphragm wall is Total Station Leica Viva TS15PR1000 and GOCA monitoring
software [3], [39]. The monitoring data are transmitted back to computer. The
function of processing data automaticlly of GOCA software will give us the graphic
graph on deformation of the monitoring points fixed on the diaphragm wall.
This automatic monitoring system has more outstanding advantages than the
traditional technology; those are: high accuracy, the quickest result provision time,
the most information provision, the maximum reduction in measurement and

calculation errors caused by people.
5.1.2. Experiment on monitoring the displacment of the diaphragm wall of the
work of the Authority of Radio Frequency Management by combining the method
of surveying and using Inclinometer
To vertify the above theory, we have experimented five monitoring locations
(ICL1, ICL2, ICL3, ICL4 and ICL5) of the diaphragm wall of the work of the
Authority of Radio Frequency Management at No.15 Tran Duy Hung. At each
21

location of monitoring the displacement using Inclinometer, we determined the
displacement of the center of the pipe mouth by surveying.
After calculating and determining the deviation of the center of the mouth of the
guide pipe using two above methods; in this case, consider the bottom of the guide
pipe as stable. Thus, this deviation is the closing error of the two methods. We
distribute this error to the measuring points inside the guide pipe using formula (3.43).
In so doing, we could determine the displacement value with increased accuracy.
5.2. Experiment in developing the foundation settlement model of high-rise
buildings in the foundation and basement construction period
5.2.1. Experiment in developing the settlement model for the foundations of Office
No. 22-24-26 Mac Thi Buoi, Ho Chi Minh City
Based on the settlement monitoring data (coordinates, settlement and settlement
mean square errors) of 14 settlement monitoring marks [40], use 11 settlement
monitoring marks to develop the model and three remaining marks to compare with
the settlement that is interpolated from the model. By using ADFB software for
developing the model, the obtained result as follows:
Settlement plane equation:
S = -0.0000001x + 0.0000056y -0.00792 (m) with model error of: 0,13mm.
Evalution of the work foundation deformation:
From the settlement mean square errors of 11 monitoring marks that are used in
developing the model, calculated m

0
= 0,44mm. At that time:
2
2
0.13
F 0.09
0.44
; F
gh
= F
α=0.05
(8,11)

= 2.948
gh
FF
, which means that the work foundation is not deformed.
The results on developing the model and comparing the actual settlement and
the one that is interpolated from the model show that developing the settlement model
in accordance with the plane method is appropriate in this case. When developing the
model, applying the adjustment analysis will permit evaluating whether the work
foundation is deformed or not.
5.2.2. Experiment on developing the foundation settlement of the Ha Noi South
Transaction Center and Call Office
Based on the settlement monitoring data (coordinates, settlement and settlement
mean square errors) of 10 settlement monitoring marks [41], use 08 settlement
monitoring marks to develop the model and two remaining marks to compare with
the settlement value that is interpolated from the model. By using ADFB software for
developing the model, the obtained result as follows:
Paraholic foundation settlement model:

S = -0.02773 + 0.0001905x + 0.0012355y -0.0000134x
2
+ 0.0000004xy + 0.0000492y
2
(m) with model error of: 0,76 mm
The results on developing the model and comparing the actual settlement and
the one that is interpolated from the model show that developing the settlement model
using Parabol function is appropriate.
5.3. Experiment in developing the displacement model of the diaphragm wall
22

5.3.1. Experiment in developing the displacement model of the diaphragm wall of
the Golden Palace, Hanoi ona horizontal plane
Based on the displacement monitoring data (coordinates, displacement and
displacement mean square errors) of 15 displacement monitoring marks, use 10
displacement monitoring marks to develop the model and five remaining marks to
compare with the displacement value that is interpolated from the model. By using
ADFB software for developing the model, the obtained result as follows:
Displacement model of the diaphragm wall on a horizontal plane:
q
x
= -0.0009800 - 0.0000318Y + 0.0000095X (m)
q
y
= 0.0012200 + 0.0000318X + 0.0000095Y (m)
With model error of: 2,49 mm
Evaluation of deformation of the diaphragm wall:
From the displacement mean square errors of 10 monitoring marks that are
used in developing the model, calculated m
0

= 1,72 mm and have:

2
2
2.49
F 2.096
1.72
; F
gh
= F
α=0.05
(16,20)

= 2.20
gh
FF
, which means that the diaphragm wall is not deformed.
The results on developing the model and comparing the actual displacement and
the one that is interpolated from the model show that developing the displacement
model of the diaphragm wall on a horizontal plane is appropriate. Adjustment analysis
permits evaluating whether the diaphragm wall is deformed or not.
5.3.2. Experiment in building the displacement model of the diaphragm wall on a
vertical plane
Based on the displacement monitoring data (coordinate x, height H,
displacement value in the direction perpendicular to the diaphragm wall and
displacement mean square errors) of seven monitoring marks [42], use five
monitoring marks to develop the model and two remaining marks to compare with
the displacement value that is interpolated from the model. By using ADFB software
for developing the model, the obtained result as follows:
Displacement plane equation:

q = -0.0000444x -0.0003826y -0.00024 (m) with model error: 2,95mm
Evaluation of deformation of the diaphragm wall:
From the displacement mean square errors of five monitoring marks, calculated
m
0
= 1,29 mm and have:
2
2
2.95
F 5.229
1.29
; F
gh
= F
α=0.05
(2,5)

= 5.786
gh
FF
, which means that the diaphragm wall is not deformed.
The results on developing the model and comparing the actual displacement and
the one that is interpolated from the model show that developing the displacement
model of the diaphragm wall on a vertical plane is appropriate in this case. When
developing the model, applying the adjustment analysis will permit evaluating the
deformation of the diaphragm wall.

23

5.4. Experiment in analyzing simple linear correlation between underground

water and foundation settlement of high-rise buildings
The experiment part will analyze and evaluate the dependence level between the
settlement value of the foundation on the underground water based on the data on
monitoring 37 cycles in the excavating process for constructing the foundation and
basement for a real work [42], [43]. The obtained data in each cycle consist of:
monitoring time, underground water height and settlement value of each monitoring
mark BM15. By using ADFB software, obtain final results as follows:
1. Correlation coefficient:
xy
r 0.68

2. Fisher function: Z = -0.83
3. Adjustment of value Z:
Z
0.17

4. Regression equation S = -0.03546H -0.34475 (m)
The correlation analysis results above show that: the settlement of the work
foundation and underground water have a moderate correlation relationship.
The experimenting results show that the simple linear correlation analysis
method which is used to evaluate the dependence level of displacement on one factor
that could affect that displacement is completely appropriate. This method helps us
know whether the element we doubt to affect the work displacement affects or not;
and, when this element affects, how the dependence level of this factor on the work
displacement is.
5.5. Experiment in predicting the work settlement by the Plynomial function
The experimenting process is conducted for one mark (Mark NT11), measuring
settlement of parent rock of the work of South Ha Noi Transaction Center and
Switchboard, No.811 Giai Phong Street, Ha Noi [41]. The parent rock is measured 11
cycles (excluding the first monitoring cycle]. The monitoring data consist of time,

settlement and settlement mean square error. The data of seven cycles (from 1
st
cycle
to 7
th
cycle) are used to develop the model; the data of 8
th
-11
th
cycle are used as the
results for evaluating appropriateness level of the theoretical and practical analysis.
We develop the model from level 1 to level 5 alternately and evaluate the model
reliability of the model through adjustment analysis. The results show that
polynomial of degree 1 to degree 5 all has F<F
gh
. The polynomial of degree 2 that is
the one with the smallest degree has the model error equal to the settlement
measurement error. Thus, it is selected to be the prediction model and the model is as
follows:
2
t
S 0.711 3.987t 0.045t
(mm)
When using the plynomial function to predict the settlement, the more accurate
the predicted result is when the close the interpolating point is close to the final
monitoring cycle. The further the predicting point is the monitoring time in the final
cycle, the higher the error is; the predicted settlement value has low accuracy. In the
model development process, it is necessary to analyze the adjustment to evaluate the
reliability of the model.