tóm tắt luân án nghiên cứu hiện tượng dịch chuyển đất đá trên sườn dốc vùng đồi núi quảng trị thừa thiên huế, đề xuất phương pháp dự báo và phò

MINISTRY OF EDUCATION AND TRAINING
UNIVERSITY OF MINING AND GEOLOGY







NGUYEN THI THANH NHAN






RESEARCH ON THE MOVEMENT OF ROCK AND SOIL ON
SLOPE IN THE MOUNTANIOUS REGION FROM QUANG TRI
TO THUA THIEN HUE AND PROPOSITE THE SUITABLE
PREDICTION MEASURES

Specialty: Geological Technology
Code: 62.52.05.01





SUMMARY OF DOCTORAL THESIS IN GEOLOGY

Hanoi - 2014


The research has been accomplished at:
Engineering Geology Department, Geological Faculty
Hanoi University of Mining and Geology



Supervisors:
1. Assoc. Prof. Dr. Ta Duc Thinh,
Ministry of Education and Training

2. Prof. Dr. Nguyen Thanh,
Viet Nam Association of Engineering Geology and Environment


Examiner 1: Assoc. Prof. Dr.Nguyen Huy Phuong
Viet Nam Association of Engineering Geology and Environment

Examiner 2: Assoc. Prof. Dr. Pham Huu Sy
Water Reoursces University


Examiner 3: Dr. Phan Sy Thanh
Viet Nam Hydraulics construction consultant corporation - JSC






This thesis is going to be defended at the committee of doctorate
thesis examiners of Hanoi University of Mining and Geology, Duc
Thang ward, Bac Tu Liem district, Hanoi, Vietnam on 08:30 date
… month… year 2014.




This thesis can be found at National Library, Ha Noior Library of
Hanoi University of Mining and Geology

1

PREAMBLE
1. Necessity of thesis
The mountainous areas from Quang Tri to Thua Thien Hue accounted for
more than two thirds of the territory with rugged topography, many passes and
tropical monsoon climate, in the floody seasons, the lanslide on slope occured

frequently with all scales and focused mainly on traffic way, especially HCM
highway and hydraulic construction.
The process of moving rock on slope destroyed slope, road bed; made traffic
jams and caused great damages to people and property. But researches on geo-
dynamic on slope in research area are limited as following that many problems
about natural, causes, results, conditions, dynamic, rules, classification, … as
well as prediction, preventation and mitigation measures, which caused by
landslide, were not reserached in deepen. So, the selection of thesis topic is very
necessary and highly signification in science and practical (figure 1)




















Figure1. The diagram of the mountainous area from Quang Tri to Thua Thien Hue

2. Purpose of thesis
- Determine the current status, causes, dynamics and distribution laws,
development of the moving rock on clope in research area.
- Establish the zoning and prediction lanslide map on slope in research
area and proposite the suitable prevented measures to meet demand the
sustainable socio-economic development.
3. Research objects and Scope
- The research object is Natural - Technical environment in the
mountainous area from Quang Tri to Thua Thien Hue, focus on slopes and the
2

process of moving rock on slope (mainly acts is landslide). In which, the
opinion in slope of thesis is including natural and artificial.
- The research scope includes in the mountainous area from Quang Tri to
Thua Thien Hue with 50 meters in height. The research depth is equal and more
50 meters from the ground floor to the relatively stable soil layer below.
4. Research content
- Overview of research on the moving rock phenomenon on slope.
- Study on the characteristics of natural - techinical environment in
research area.
- Research on the moving rock processes in the mountainous area from
Quang Tri to Thua Thien Hue.
- Prediction the risk of arising moving rock on slope in research area.
- Research and proposite the prevented measures on slope in research area.
5. Reasearch method
- Collection, inherition, analysis, synthesis the selective information and
research results; system analysis methods; expert method; Remote sensing
image analysis method; Mathematical - mapping modeling method;
6. New points of thesis
- The analysis, evaluation of natural - technical elements and their effect

to the fomation of moving rock on slope in research area.
- Proposition the classification of the moving rock on slope in the
mountainous areas form Quang Tri to Thua Thien Hue.
- The successfully application of Mathematics - Mapping model method with
GIS technology to evaluate the intensity of moving rock on slope in the
mountainous areas form Quang Tri to Thua Thien Hue, which were based on the
basic of the establishment multi - criteria of natural - techinical conditions system.
7. Main defendable contents
The 1
st
Content: The processes of moving rock on slope in research area are
the result between natural environment elements and economic - engineering
operations. In which, the road construction and highly rainfall in long-term are
the main causes of all processes on slope.
The 2
nd
Content: The landslide phenomenons on slope in the mountainous
from QT to TTH have the diversified and complex natural - technical
environment, which can be evaluated, predicted by Mathematics - Mapping
model with GIS technology in 5 levels from very weak to very strong.
Including, the intensity of landslide level from strong to very strong - takes
about 44,58 percent, gather mainly on slope which were belong to commune’s
traffic road in Huong Hoa dist, A luoi dist, Nam Dong dist.
8. Scientific and reality signification
- Contribute to improve the theoretical basis, methodological research on
the moving rock on slope.
- On the basis of the prediction and zoning the risk of moving rock on
slope, proposite the suitable scientific - technological prevented measures to
mitigate the damages of the moving rock in the mountainous from QT to TTH
3

- The research results are the documents on trust which can be refered and
used on planning, reasonable exploitation in territory, design, construction all
projects - especially road construction; to meet demands the Social - Economic
development and ensure the suitable national security and defence in research area.
9. Main basics of references
The thesis was accomplished by all documents which were collected
through 7 field trips in Nov, 2008, Jan, 2009, Oct, 2009, May, 2010, Feb, 2011,
Nov to Dec, 2013 and Jan, 2014; three scientific research projects, which i were
a chief of editor, are one in ministry level and two in University level. The
Geological survey report of sustainable construction project which be caused by
flood in 2009 on Ho Chi Minh route in stage from Quang Binh to Kon Tum;
The volume of landslide report on HCM route from QT to TTH from the year
2006 to 2013; The engineering geological survey reports of landslide points on
HCM route, route No.49, route No.14B, ; with all publishing documents were
announced in domestry and international.
10. Structure of thesis
The thesis content was shown on 5 chapters and illustrated by 12 maps, 34
datasheets, 9 figures and charts, 18 pictures, 8 table appendixes, 44 picture
appendixes; With 9 publishing scientific journals and 110 catalogs of reference.

Chapter 1. THE OVERVIEW OF RESEARCH ON MOVING
ROCK AND SOIL ON SLOPE
1.1. Research situation in moving rock and soil on slope in over the world
Research on moving rock and soil phenomenons were deployed reality in the
15
th
to 18
th
century, began to develope deeper and wider in the 19

th
century and
reached the peak in the 20
th
century to nowadays. More notable are the works of
Dranicov A.M,1949; Fukuoka M,1953; Popov I.V,1959; Sharpe C.F.S,1938;
Terzaghi K,1950 ; Emelianova E.P,1972; Lomtadze V.D,1982; Seed B,2000 and
so on…. And UN Organization are UNESCO (United Nations Educational,
Scientific and Cultural Organization), UNDP (United Nations Development
Programme), UNODRR/ UNISDR (United Nations International Strategy for
Disaster Risk Reduction/United Nations Office for Disaster Risk Reduction),
In addition to mention the allocation of landsilde slope positions, all scientists
have forcused on elucidating mechanisms of movements, tophographical features,
geological structures, hydrogeological conditions, engineering - economic
operations and all elements which affected to the motivation and rules of arising
moving rock and soil.
1.2. Research situations of moving rock on slope in Vietnam
In Vietnam, the moving of rock on slope occurred popularity. In current
years, there’re some research projects on the lanslide which were based on
many different approachable pointviews. Notably that the projects of the
Institute of Geology, Academy of Sciences of Geology and Mineral Resources,
Institute of Science and Technology, Transportation, A number of typical
research projects according the direction of geodynamics have been published
4

by the authors such as: Tran Trong Hue, Tran Tan Van (2006), Dau Van Ngo
(2004), Nguyen Trong Yem (2006), Ta Duc Thinh (2007), Doan Ngoc Toan,…
Some topics based on the viewpoints about systematic approaching and using
GIS technology, specialized software to research on natural hazards such as:
Nguyen Trong Yem, Nguyen Quoc Thanh, Pham Van Hung, The technical

cooperation project between the Ministry of Transportation and JICA " The
development of risk assessment technology by landslides along the main roads
in Vietnam" by the Institute of Science & Technology Transport chaired and the
project ”Investigation, assessment, zoning and warning the risk of landslide in
the mountainous areas of Vietnam" (2012 - 2020), by the Academy of Sciences
Geology and Mineral Resources chaired begun to be implemented, promises to
provide convinced scientific arguments about landslide phenomenon along the
main roads and in the mountainous areas of Vietnam. However, so far there
have not been any research projects which weren’t systematic, detailed, not
built into the database and mapping the warning map on landslide to proposite
suitable preventive measures and reduce the damages were caused by moving
rock in this area. The research project results will perfect the methodology as
well as solving problems above.

Chapter 2. NATURAL - TECHINICAL ENVIRONMENT FEATURES
IN THE MOUNTAINOUS AREA FROM QUANG TRI
TO THUA THIEN HUE
2.1. The features of climate regime and hydrology in research area
2.1.1. The features of climate regime
Located in Tropical Belt of the Northern Hemisphere and inherited abundant
radiation regime so that the temperature of the mountainous area from QT to
TTH is very high, which is deeply effected by wet tropical monsoon climate
regime with plentiful rainfall, the total of average rainfall per many years are
about from 2200 to 3000 milimeters, somewheres are more 4000mm. The wet
season in research area begin from the end of May to December (Huong Hoa,
Kha Sanh with 2672,2 mm of rainfall, make up about 55 to 66% of rainfall per
year. The largest daily rainfall gather on sept, oct, nov with 426,4 mm to 927,3
mm ( in A luoi, the rainfall reached 658 mm on September 29
th
, 2009 ). In every

years, there are from 4 to 8 rains extend from 2 days to 6 days, individual,
somtimes can be 8 to 9 days with the popular rainfall ranger between 150 - 400
mm and 600 - 1125mm. Because the concentrated rainfall were large rainfall
and high intensity of raining and occured frequently in several days so this’s the
favorable time of frequently occuring the moving rock and soil strongly in the
mountainous area from QT to TTH.
2.1.2. The features hydrology
River basins in research area arn’t often wide, high standing degree, the
river length is short and slope which changes abruptly when adjacent to plains.
However, the river systems on research area are often far away from main road
so that dont effect significantly to the moving rock and soil on slopes.
2.2 The geological structures in the mountainous area from QT to TTH
5

According to Geological and Mineral Map with scale 1:2000, the
moutainous area from QT to TTH composed of sedimentary formations and
sedimentaries, which are vocanic original, developed deversiflilly and
distributed discontinoustly from Paleozoic Era to Kanozoic Era. Including 14
formations: (Nui Vu (NP-

1
nv), A Vuong (
2
- O
1
av), Long Dai (O
3
- S
1
lđ),

Dai Giang (S
2
- D
1
dg), Tan Lam (D
1
tl), Co Bai (D
2-3
cb), La Khe (C
1
lk), Bac
Son (C - P

bs), A Lin (P ? al), Cam Lo (P
2
cl), A Ngo (J
1
an), Mu Gia (K
2
mg),
Neogene (N) and Quaternary (Q)), 10 instructive magma complexes (Hiep Duc
PZ
1
hd), Nui Ngoc (GbPZ
1
nn), Dieng Bong (GPZ
1
db), Tra Bong (D
i
- GD

i
O-
Stb), Dai Loc (G
a
D
1
Ddl), Ben Giang - Que Son (GD
i-G
PZ
3
bg- qs), Chaval
(Gb
a
T
3
cv), Hai Van (G
a
T
3
hv), Ba Na (GE
2
bn), Mang Xim (SyE
2
mx) ), which
have the different lithological composition, intersperesed distribution in small
territory and diversifilly manifestations of geo - environment.
However, the moving rock and soil on slope are not arisen at 24 units of
formation and occured mainly in intrusion magma formation, metamorphism rock,
sedimentary rock which have original of land, have lithological composition of
multi-mineral, features of structure and architecture which could be whethered and

intensitive to the moving of rock and soil as following: complexes of instrusion
like Ben Giang - Que Son and Hai Van complexes, and A Vuong formation, Long
Dai formation, A Lin formation, Tan Lam formation and more something else.
2.3. Wheathered features and mechanical propeties of rock which composed
by zone and sub-zone of weathering
The mountainous areas from QT to TTH have complicated geological
structures and varied lithological composition of bedrock (sedimentary rock,
magma and metamorphism) containing up to 20-98% minerals easily weathered. In
addition, the abundance of tropical moisture regime, monsoon increases the speed
of the chemical reactions, this is a favorable environment for the moving rock and
soil arise with diffirent scale and intensities. The deeper penetration of the
weathering factors should be limited as the level of weathering decreases, make the
weathered rock (weathering crust) have the zonation clearly in depth and presence
of weathering tropical, sub- weathering tropical: edQ, IA
1
, IA
2
, IB, IIA, IIB which
with mechanical properties decrease as weathering intensity while the empty void
ratio increase with the extents of weathering. In saturated state, the compression
resistance strength of rock and the shear resistance strength of soil reduce
significantly from their natural state and reverse. The increase in unit weight of soil
and decrease the shear parameters (φ, c) of the water-saturated soil causes the
arising weathered rock slide on the slope of roads, the large foundation pit,
2.4. Hydrogeological features in research area
Starting from the perspective impact of groundwater as one of the main
reasons caused the slope geological disasters, especially landslides and rock.
Underground water appeared and move swepty under moutainous slope which
caused incrise unit weight, reducing shear resistance force of rock, creating
hydrostatic pressure (Aw) and hydrodynamic pressure (Dw) to reduce

resistances sliding force, increase dynamic force, that are decrease the stable
index, causing structural landslide on slope. On the basis of field surveys,
identifying the flow of arteries, pumping documents, water injection tests in a
number of drill holes, the author did not stratify Hydrogeology and descrision the
6

hydrogeological stratum units by traditional hydrogeological territorical method
which generalize traditionally the hydrogeological features follow the plentiful of
water as: group of Hydrogeological complex in fissures- poor water seams,
Fissure - poor water seams, which added water average level water containing,
fissure - seams, cracks rich water; Fissure - karst - a rich seam of water.
2.5. Topographical - geomorphological features and vegetation cover of the
reearch area
2.5.1. Topographical - geomorphological features
The research mountainous topography has stepped structure quite clearly:
The medium mountains in the West, the lower mountains interspersed between
the hills and valleys in the middle and small - narrow strip plains in the East.
Typical topographical forms following: medium block mountainous terrain,
tectonics - denudation, lower tectonic - denudation mountainous topographical
structure, Karst denudation mountainous terrain, mountainous terrain before
erosion and denudation. Howerver, through field surveys showed that almost
the points of moving rock and soil occured strongly in medium block tectonic -
denudation mountainous terrain have absolutly height from 500 meters to 800
meters, more than 800 meters, the forest coverage up to 70 - 80%, highly slope
with popular from 26 degrees to 45 degrees, deeply division from 300 to 500
meters per square kilometer.
2.5.2. Vegetation cover
The mountainous area from QT to TTH has a rate of coverage is high
compared with the country, make up from 20% to 80% (Huong Hoa, D’Krong,
Huong Thuy, Phu Loc, A Luoi, Nam Dong), but it’s not equal ( follow some

statistic datas of Forest Inventory and Planning Institute). Through field surveys
showed that moving rock and soil phenomenon occur in many places of the
research area, concentrated mainly in Huong Phung commune, Huc Nghi
commune, Ta Rut commune, A Ngo commune, Hong Thuy commune and A
Roang commune and once of main causes is deforestation for wood, burning
forest for agriculture and growing industrial trees along to slope in research
area. The deforestation, burining forest created the denuded sloping, reduce
the rate of forest cover lead to rapid increase moving rock and soil process.
2.6. Economic - construction operations
Economic - construction operations include specific trait, prominent and
influential to the moving of rock and soil on slope (building road,
deforestation, ). These activities made slope and height have been overcome
their stable limit that created favorable condition for formation of weak points,
increase the driving forces, reducing amount of slip; And led to the slopeslide
when the slip factor was enhanced. In Specifically, because the activities of
selecting the route and construction surveys were less suitable for stability slope
conditions, slope territory construction; garbled slopes, construction of highly
and steepy slope that were mainly factors caused the landslide on slope of road;
Deforestation and Burning forest for agriculture are becoming a significant
cause of landslides on slope; lanslides and slope of construction were loading
by the increase in slip force, building the instability slope processing projects
which are unreasonable about forms, insufficient quantity, quality, solidly and
the risk of slope failures were created on roads,
7

CHAPTER 3. RESEARCH ON THE PROCESSES OF MOVING
ROCK AND SOIL ON SLOPE IN THE MOUTAINOUS AREAS
FROM QUANG TRI TO THUA THIEN HUE
3.1. Current status of moving rock and soil on slope in research area
Through seven field surveys (November,2008; January,2009;

October,2009; May,2010; February,2011; November to December,2013;
January, 2014), along with documents of the remote sensing image analysis saw
that in the mountainous areas in research had 420 points of the moving rock and
soil on slope and sloping roof. In particular, sloping roof on the road, including
construction had 381 points ( about 90,71%) and slope had 31 points (about
9,29%), specifically as following:
3.2 Causes and arising conditions of the moving rock and soil on slope
3.2.1. Arising conditions of the moving rock and soil on slope
The causes of the moving rock and soil on slope and sloping roof are
dynamic affecting factors, natural or artificial, including the primary causes
(directly) and secondary causes (indirectly).
Table 1. The main traffic routes from Quang Tri to TT - Hue
Order Locations
Sloping
Roofs
Slopes
1
Highway No.9 and nearly mountainous
are
16 1
2
Vinh Khe - Cam Lo (West part of HCM
highway)
9 3
3
The West branch of HCM highway
from Quang Tri to TT- Hue
322 26
4
Highway No.49 and nearly mountainous

area
19 4
5 Highway No.49B and neighboring areas 8 1
6 Highway No.1A and neighboring areas 7 2
Total
381 39
420
3.2.1.1. Economic - engineering construction activities
Economic - engineering activities such as a main cause including
operations as mutilation on slope, the newly buiding and expanded of old traffic
routes that made sloping roof degrees were more higher than natural status; The
breaking balanced status of slopes; The slide forces were more larger than
resistance slide forces leading to the moving of rock and soil occured
completely on slopes and sloping roofs, which were shown at sub-section 2.6.
3.2.1.2. Impacts of rainwater and underground-water
Heavy rains with high intensity, lasted will create large surface flows that
caused the eroison of slopes and sloping roofs, big flow dynamic will form many
collaped blocks, landslide, rockfall with different scales. Especially, the debris flow
reduce the linkages of the cornerstone with rock mass surrounding. Rainwater and
underground water increases significantly the natural volumetric massof rock and
8

soil from 1.79 - 1,99 g/cm
3
in dry seasonand in the wet season it can be reached
1.87 - 2,05 g/cm
3
. Besides, these two parameters, which are φ and C of wreak slope
soil, declined strongly; In natural state, φ = 20 - 25
0

and C = 0.23 - 0.30 kG/cm
2
and
in water-saturated, φ = 18 - 22
0
and C = 0.14 - 0.25 kG/cm
2
. When affected by
increasing volumetric mass, reducing shear resistance forces, hydrostatic pressures
and hydrodynamic pressures, the stability coefficient of sliding reduced (MD)
abruptly (η <1) so that MD is instable, lanslide occured powerfuly.
3.2.1.3. Wheathering
The wheathering reduced belf of wheathering parameters are C and φ.
Specifically, the value of C and φ of wheathering rock from medium to light,
fresh material of some formations, complexs as follow: C = 65-248 kgf /cm
2
, φ
= 35 - 49
0
. But the rock of these formations is wheathred completely into kind
of clay, the value of C decline, this time C = 0,19 - 0,32 kG/cm
2
and φ = 23 -
28
0
, that caused the unstablity of slope and sloping roof in research area.
3.2.1.4. Techtonics Movement
Neo - techtonic movement is the process of lifting and lowering to the
rhythm. This is the deciding factor should be the topography level distribution.
The moving rock and soil in the mountainous from QT to TTH occured in strongly

lifting neo - techtonic areas where have systematic actively techtonic faults as:
Rao Quan - A Luoi, Linh Thuon - Huong Lap, Huong Lap - Vinh Chap; Deeply
faults as: Dakrong - A Luoi; Route No.14 ’s fault; And Ta Lao - Van Xa - Hue,
Quang Tri - Hue - Phu Loc, etc.
3.2.2.
Development Condition of moving rock and soil on slope and sloping roof
The Conditions are static and natural influencing factors which can support
or constrain the process of moving rock and soil on slope and sloping roof.
3.2.2.1. Lithological composition, structure of rock and soil
As for the slope and sloping roof are composed mainly from the geological
formations, which be rich in rock and layer structure, contain containing many
minerals susceptible to weathering turned into soil type of macadam clay soil,
blocks - distribute on a large scale and thickness is about over 15 meter. These are
the favorable environment for massively arising of landslide with different scales
and most intensity (367 slip points, about 87.4%). Wheathering soil from intrusive
magmatic rocks also occur landslide, but less than, (53 points which accounted for
12.6% of the total slip points) which have just been encountered on the Ho Chi
Minh highway in the section from Sa Mui pass to A Roang commune. For the
wheathering soil from other bedrock found little slip phenomenon.
3.2.2.2. Features of destructive tectonic faults
Features of destructive tectonic faults are the type of destruction enclosed
the form of fragmentation, moving fragmentary parts which can be broken by
geological formations, That means the precondition for the arising and
development of the gravity shifting soil in areas which have high intricate and
re-operation fault systems as Vinh Linh - Hai Lang fault system and Rao Quan -
A Luoi fault system), The capable of arising and implicit risk of landslide when
the rock is fragmentary, undrain , uncohension and the mechanic properties of
9

rock, especially interior friction angle and cohension force reduced

suddently, etc that make reducing of shebar resistanceof rock and occuring
unstable slope phenomenon.
3.2.2.3. Thickness and shear resistance force of strongly and completely
wheathering rock and soil
The points of moving rock and soil on slope and sloping roof developed
mainly on the wheather crust in sub - zone ( (edQ + IA
1
) of the terrigenous
sediments, terrigenous eruption, metamorphic and magma rocks of Long Dai
formation, Ben Giang - Que Son formation, A Lin formation, Tan Lam formation,
A Vuong formation, with the popular thickness of wheathering crust from 15.1 -
25 meters to 25,1 - 35 meters and φ = 32 - 20
0
, C = 0.75 - 0.1kG/cm
2
.
3.2.2.4. Degrees of slope and sloping roof

The moving rock and soil in the mountainous area from QT to TTH have large
scale and occured mainly on slope in from Sa Mui pass (km 211 + 700); (km 231 +
500) to Huong Phung - Dkrong; km 381 to km 408 + 165 from Hai Ham pass to A
Luoi district, are the areas which have the height about 500 meters to 800 meters
or more 800 meters with slope degrees from 26 26
0
to 45
0
and more 45
0
.
3.2.2.5. Vegetation cover

The moving rock and soil encountered many areas and concentrated
mainly in the communes as Huong Phung, huc Nghi, Ta Rut, A Ngo, Hong
Thuy, A Roang and in forest areas mainly as shrubby trees, cogon, with
canopy cover from 30 to 10 percent, in areas of industrial and agricultural trees,
especially in buring foresting for cultivation with large scale areas.
3.3. Mechanisms, dynamics and laws of formation and development of the
moving rock and soil on slope
3.3.1. Mechanisms
In the research area appearing all 4 types of modal movings of rockfall, lanslide,
collapsable rock and soil, debris flow. Also arise both types of complex moving.
3.3.2. Dynamics
The Dynamic of moving rock and soil in research area research showed
that can be devided to 3 preiods: Preparation period of moving rock and soil,
Formation preiod of moving rock and soil and Re-stabilization period which
tended to decrease over the time in intensity, frequency of landslides.
3.3.3. Laws of formation and development
The process of moving rock and soil occurred with the stage, cyclical and areas:
3.3.3.1. Frequency of landslide closely related to average yearly rainfall
In the rainy and flood season, landslide occured strongly and popularity when
the intensity of average rainfall per year ranged from 3001->3400 mm per year
(81,7%),; When the intensity of rainfall ranged from 2200 to 3000 mm per year, the
landslide occurred weak (17.1%); which small intensity of rainfall less than 2200
mm per year just happened in Khe Sanh Valley,the lanslide occured negligibly.
3.3.3.2. Intensity of moving rock and soil depend on type, operation scale of economic
and engineering construction
The moving rock and soil occurred in strongly areas where were affected by
10

activities of economic - engineering contruction (road construction and burning
forest for agriculture are relatively popularity)(84,0%); The areas were far from

traffic routes or the effect of human impacts as indiscriminate cultivation on
slope, deforestation for wood, agriculture and small building so that the moving
rock and soil didn’t occur significantly (6%)
3.3.3.3. Distribution characteristics of moving rock and soil points associated
with stratigraphy - lithology
According to the survey results, with 367/420 moving rock and soil points
(accounting for 87.4%) occurred in the rock formations related to terrigenous
sediments, metamorphic rocks; 53/420 moving rock and soil points ( accounting
12.6%) related to magmatic rock. The moving rock and soil occured mainly in
sandy clay and rubble, blocks which belong to A Vuong formation (25.7%), Long
Dai (23.1%), A Lin (14.5%), Tan Lam (11.4%), Ben Giang - Que Son (10.2%),
3.3.3.4. Distribution characteristics of moving rock and soil points associated
with the weathering crust thickness
The moving rock and soil developed strongly on slope and sloping roof had the
popular thickness of whearthering crust about 15,1 to 35 meters (81,6%); with a
thickness of 5-15 m (8.2%), more than 35 m (8.8%), with thin weathering crust
thickness less than 5 m, The landslide didn’t occur significantly (1.4%)
3.3.3.5. Frequency of moving rock and soil have close relationship with slope degrees
The moving rock and soil were most concentrated on slope which be from
31 degrees to 600 degrees (59.5%), less than on slope from 15 degrees to 30
degrees and the slope is more than 60 degrees (15,2%), with slope degree less
than 15 degrees, the landslide litte occured.
3.3.3.6 The processes of moving rock and soil in research area occur unevenly
according to the moving type (mechanisms)
The laws of distribution moving points of rock and soil by type
(mechanisms) of moving on slope and sloping roof in research area as
following: Dominant landslide (53.4%), the second is collapsable rock and soil
(30.4%), debris flow (15%), rockfall (5%).
3.4 Propose classification methods of the process of moving rock and soil
on slope in research area

Regional classification of moving process of rock and soil are the
synthesic classified but attached to the object classification aka with the areas,
geological sphere, certain topography - geomorphology. It was also known as a
database to more accurately assess sliding stability or when choosing preventive
measures to prevent specifically and effectively landslide hazards.
a. Selecting the hierarchical classification of moving rock and soil
Based on the thorough study of the principles the hierarchical and the
classification criteria had interpreted, regional classification scheme diagram of
moving rock and soilon slope in the mountainous areas of Quang Tri - Thua
Thien Hue with 2 types: type and form.
b. Selection the criteria for the classification process of moving rock and soil
Type of moving rock and soil: be divided according to the general
11

characteristics of the mechanism (mode) and moving (down, fall, slide, flow, ).
Form of moving rock and soil: is a specific modal moving to destruction
surface ( sliding surface) ( non - available slip surface; curved slip surface; flat
slip surface and wavy slip surface, ) have given shape and lithological
composition of rock and soil ( percentage of soil (<0.02mm), rubble (0,02-0,2m)
and rock ( block more than 0,2m), which were mentioned in the table below:
Table 2. Classification the types of moving rock and soil in the mountainous
area from Quang Tri to Thua Thien Hue
Types Types of moving rock and soil Landslide points
Group of homogeneous type
Falls
Rockfall. The process of moving
block on slope based on sliding and
rolling mechanism follow sloping
surface (reached to 90 degrees) and
fall down to the end of slope.

Rockfall is about 50 meters
volume

at km no. 298 + 300
near Dkrong bridge, Quang
Tri

Collapse
Collapsable rock. Block, rock
separated from the slope (70-80
sloping degrees) or sloping roof
of he trench dug, the open pit
banks were not under the clearly
destruction surface, nearly
vertical moving (free fall) to the
end of slope.
Drop more than 1000 volume
metres of limestone blocks
down the HCM highway in the
section km 287+680, Tan Nghi
commune km248+300,
km298+300 Ta Rut commune,
km387+250 ARoang - A Luoi
Collapsable rock and soil.
Almost vertically moving of
rock and soil mass not follow
clearly destruction surface with
soil particle size (<0.02m) and
debrish crushed stone, boulders
(> 0,02m) ranged from 20-80%.

Land subsidence at km 191+820;
km 200+790, km 201+ 200 Khe
Sanh - Cha Ly, Quang Tri, in
Route No.9 at km48+470, km
315 +50 Hong Thuy commune -
A Luoi, km 383 + 100 A Roang
commune - A Luoi…
Collapsable soil. The soil blocks
contain high levels of Crushed
debris, boulders (> 0,02m
accounted for <20%), with
natural texture completely was
destroyed, almost vertical
moving didn’t follow a clearly
destruction surface
Land subsidence at km 205,
206 + 200 Khe Sanh - Cha
Ly, km 75 + 150 route
No.49, Hong Tien - Huong
Tra communes, km 319
+850 Hong Thuy - A
Luoi,….
Slides
Rotating slide of rock mass is the
type of moving not follow
available surface, under the curved
rotating slider blocks in the
uniformity and unstable
wheathering levels of rock and soil
Typical rotating slide point of

rock mass at km 281 + 550 Huc
- Dakrong communes, km 314
+251 to 314 +550 Hong Thuy
commune (A Luoi) belong the
section in PeKe pass
Flat slide of rock blocks that is
more popular type than rotating
slide, which follow available

Translational landslide of
rock mass at km 206 + 200
12

Types Types of moving rock and soil Landslide points
surface, often araising in hard rock
with weakly multi-faceted
(Classification, assignment, surface
cracks, faults, rupture zone, ) or in
strongly weathering zone of rock
and soil that is relatively thick (<3-
5m), with shear resistance force is
much weaker than bed rock and
translational movement along the
visible plane of weakness on slope.
Khe Sanh - Cha Ly , Route
No.9 at km 47+370, Route
No.49B km 75 + 150, km
398 + 050 - km 398 + 980 in
Hong Tien commune.
Mixed slide of rock and soil is a

major type of moving which
occur in half soil half rock
environment ( the strong
wheathering crust overlies weak
wheathering rock ), according to
the mixed mechanism between
the rotating slide (curved slide),
which be predetermined surface,
in soil and flat slide follows
weak surface (according to
available items) in rock.
Mixed slide of rock and soil
at km 206 +200 of Khe Sanh
- Cha Ly, km 280 +500 Huc
- Dkrong commune, km 383
+450 Hai Ham pass, A
Roang commune, A Luoi
Flows
Rock flow (line) is the type of
moving under the mechanism of
high speed flow (rock
containing 20-80% particle with
a diameter> 0,02m), too drain
becomes the viscid liquid when
meet the highly intensity and
lasted of rainfall
Rock amd soil flow at km
202+500 Khe Sanh - Cha
Ly, km 316+020 Hong Thuy
commune(A Luoi) in the

section Pe Ke pass, Km
391+ 664, km 403 + 270,
km399 + 900 Hai Ham pass.
Soil flow (line) is the type of
moving clay (particle
concentrations > 0.02m and less
than 20%), too drain after lasted
and heavy rain which become
viscid liquid flowing down the
surface of slope or inclination of
wavy and fractured surface of
wheathering rock and soil level
underneath the thin cover of clay.
Soil flow at km 271+600,
km 313+600 DKrong - Ta
Rut, km 200+900 Khe Sanh
- Cha Ly, 314+ 550 Hong
Thuy commune (A Luoi)
Group of Mixed moving. Those are the types of moving in the process of
mechanism moving (methods) which change (rarely up to twice). The types of
mixed moving were discovred include: fall-collapse the rock or reverse; collape -
crawled the soil; collapse - soil and rock flow and slide - rock and soil flow


13

Chapter 4. PREDICTION THE RISK OF ARISING LANSLIDE
ON SLOPE IN THE MOUNTAINUOS AREAS
FROM QUANG TRI AND THUA THIEN HUE
4.1. Purpose of prediction all processes of lanslide on slope

The important task when research on landslide on slope and sloping roof is
determining spatial scale where this phenomenon was at risk of future
occurrence with different levels (also known as the sensitivity complications of
landslide ), also called mapping the zonning landslide with their intensitivity, is
the necessary basis of planning, using, reasonable exploitation of territory.
4.2. An overview of prediction methods of the landslide process on slope in
over the world and our country
From the early middle of 21
th
century to nowadays, the evaluation of
intensitivity (damage) and prediction of potential for araising the landslide
disasters on slope has strong and deversified development which can be
combined into 5 groups of evaluation and zoning methods of these intensitivity
for landslide disaster in research area: geomorphological mapping analytical
method; Remote sensing - GIS method; Detection methods or heuristic; the
statistical and probabilistic method and deterministic methods,
4.3. Select the prediction methods
At present, there are many methods of prediction and zoning the landslide,
each method has advantages and disadvantages. Mathematical-mapping modeling
methods with the help from GIS techonology has many advantages due to its high
precision and consistent with reality. This method built a model sliding zoning
follow statistical probability based on the statistical analysis of the factors that
cause, support (promote) the sliding blocks happened to quantitatively predict
where the current landslide has not happened yet, but existed similar sliding effect
conditions with the help of computer through GIS software systems (Geography
Information system). GIS technology allowed linking caused parameters, support
to the landslide and coefficient values for specific attributes landslide with every
units of research areas, from which divides areas at risk of many different
landslides based on the analysis of attribute values and locations which landslides
occured in the entire of research space.

4.4. Mapping the zoning risk of lanslide on slope in research area
Zoning and prediction map of the risk of landslide was built on the principle
of overlapping integrated maps weighted components with the help of GIS
software technology is mainly used ArcGis 10.0.
4.4.1. Establish the systems, determine the impportant exent, intensive
impacts of main factors affecting of the landslide in mountainous areas from
QT to TTH
The results of baseline research, experimentation, observationwith the
consultation of scientists, authors conducting analysis, limited to the lowest
level of the subjective evaluation, thereby selected 9 the main factors were the
cause and mainly affecting conditions of landslide on slope in the mountainous
14

areas from QT to TTh as follow (Table 3).
Table 3. The main effected factors to the process of landside

No The main affecting factors Symbol
1
2
3
4
5
6
-
7
8
9
Sloping degrees and sloping roof
Annual average rainfall intensity
Economic - engineering activities

Lithological composition, soil structure
The density of tectonic faults
Thickness, the shear resistance strength of rock in
strong and completely subsidiarity weathering
The flow of arties
Vegetation cover
The Deep cleavage of topography
A
B
C
D
E
G
-
H
I
K

On the basis of 9 elements to choose from above, we carried out to build
systems, determine the importance of the main affected factors of the processof
landslide on slope in research area which were presented detail on table 4.
From the theory of paired comparison matrix of environmental component
factors of more importance, loss of Saaty (Table 5), we applied and proposited
the paired comparison matrix of the importance and W
i
index of 9 elements of
natural-techinical environment on slope in research were presented in Table 6.

Table 5.The comparison matrix of natural - techinical environment factors on
the moutainous areas from QT to TTH

15

Table 4. The natural - technical factors, the importance (I
i
), the intensity of their impacts (M
ij
) on construction slope
in the mountainous areas from QT to TTH
The natural - technical factors in the mountainous areas
from QT to TTH

The natural slope in research
area
The construction sloping roof in
research area
Name
No
tati
on
I
i

Impact intensity level (level
of influence) of the natural
and technical elements
M
ij

Impact intensity level (level
of influence) of the natural

and technical elements
M
ij

Impact intensity level
(level of influence) of the
natural and technical
elements
M
ij

1. Sloping
degrees and
sloping roof

, (degrees)
A 9

< 15
0
1

< 15
0
1 - -

= 15 - 30
0
3


= 15 - 30
0
3 - -

= 31 - 45
0
5

= 31 - 45
0
5 - -

= 46 - 60
0
7

= 46 - 60
0
7

= 46 - 60
0
7

> 60
0
9

> 60
0

9

> 60
0
9
2. Annual
average
rainfall
intensity R,
(mm per year).
B 9
R < 2200 mm/year 1 - - R < 2200 mm/year 1
R = 2200 - 2600 mm/year 3 R = 2200 - 2600 mm/year 3 R = 2200 - 2600 mm/year 3
R = 2601 - 3000 mm/year 5 R = 2601 - 3000 mm/year 5 R = 2601 - 3000 mm/year 5
R = 3001 - 3400 mm/year 7 R = 3001 - 3400 mm/year 7 R = 3001 - 3400 mm/year 7
R > 3400 mm/year 9 - - R > 3400 mm/year 9
3. Economic -
engineering
activities
C 9
The distance to traffic road
more than 2000m
1
The distance to traffic road
more than 2000m
1 - -
The distance to traffic road
from 2000m to 1000m
3
The distance to traffic road

from 2000m to 1000m
3 - -
The distance to traffic road
from 1000m to 500m
5
The distance to traffic road
from 1000m to 500m
5 - -
The distance to traffic road
from 500m to 200m
7 - -
The distance to traffic road
from 500m to 200m
7
The distance to traffic road
less than 200m

9 - -
The distance to traffic road
less than 200m

9




4. Lithological
composition,
soil structure
D 7

Structure of rock blocks ,
very thick layered more than
1.0m
1
Structure of stone blocks ,
very thick layered more than
1.0m
1
Structure of stone blocks ,
very thick layered more
than 1.0m
1
Rock layered with layer
thickness from1.0 to 0.2m
3
Rock layered with layer
thickness from1.0 to 0.2m
3
Rock layered with layer
thickness from1.0 to 0.2m
3
Thin bedded rock, slate feces
from 0.2 to 0.01m
5
Thin bedded rock, slate feces
from 0.2 to 0.01m
5
Thin bedded rock, slate
feces from 0.2 to 0.01m
5

rock slate feces (thin slate 7 rock slate feces (thin slate 7 rock slate feces (thin slate 7
16

The natural - technical factors in the mountainous areas
from QT to TTH

The natural slope in research
area
The construction sloping roof in
research area
Name
No
tati
on
I
i

Impact intensity level (level
of influence) of the natural
and technical elements
M
ij

Impact intensity level (level
of influence) of the natural
and technical elements
M
ij

Impact intensity level

(level of influence) of the
natural and technical
elements
M
ij

less than 0.01m) less than 0.01m) less than 0.01m)
Uncohension and soft soil 9 Uncohension and soft soil 9 Uncohension and soft soil 9
5. The density
of tectonic
faults D
f
,
km/km
2
E 7
D
f
< 0.15 km/km
2
1 D
f
< 0.15 km/km
2
1 - -
D
f
= 0.15 - 0.30 km/km
2
3 D

f
= 0.15 - 0.30 km/km
2
3 D
f
= 0.15 - 0.30 km/km
2
3
D
f
= 0.31 - 0.45 km/km
2
5 D
f
= 0.31 - 0.45 km/km
2
5 D
f
= 0.31 - 0.45 km/km
2
5
D
f
= 0.46 - 0.60 km/km
2
7 D
f
= 0.46 - 0.60 km/km
2
7 D

f
= 0.46 - 0.60 km/km
2
7
D
f
> 0.60 km/km
2
9 D
f
> 0.60 km/km
2
9 D
f
> 0.60 km/km
2
9
6. Thickness,
the shear
resistance
strength of
rock in strong
and ompletely
subsidiarity
weathering

G 7
Strongly weathered areas and
totally thickness less than 5m
with


= 35 - 27
0
, C = 1.5 -
0.25 kG/cm
2
are popolar
1
Strongly weathered areas and
totally thickness less than 5m
with

= 35 - 27
0
, C = 1.5 -
0.25 kG/cm
2
are popolar
1
Strongly weathered areas
and totally thickness less
than 5m with

= 35 - 27
0
,
C = 1.5 - 0.25 kG/cm
2
are
popolar

1
Strongly and completely
weathered areas and totally
thickness from 5m to 15m
with

= 34 - 26
0
, C = 1.0 -
0.23 kG/cm
2
are popolar
3
Strongly and completely
weathered areas and totally
thickness from 5m to 15m
with

= 34 - 26
0
, C = 1.0 -
0.23 kG/cm
2
are popolar
3
Strongly and completely
weathered areas and totally
thickness from 5m to 15m
with


= 34 - 26
0
, C = 1.0 -
0.23 kG/cm
2
are popolar
3
Strongly PH area -
completely thickness 15.1 -
25m, = 32-230, C = 0.75 -
0:21 kgf / cm2
5
Strongly PH area -
completely thickness 15.1 -
25m, = 32-230, C = 0.75 -
0:21 kgf / cm2
5
Strongly PH area -
completely thickness 15.1 -
25m, = 32-230, C = 0.75 -
0:21 kgf / cm2
5
Strongly PH area -
completely thickness 25.1 -
35m,

= 30 - 20
0
, C = 0.5 –
0.19 kgf / cm2

7
Strongly PH area -
completely thickness 25.1 -
35m,

= 30 - 20
0
, C = 0.5 -
0.19 kgf / cm2
7
Strongly PH area -
completely thickness 25.1 -
35m,

= 30 - 20
0
, C = 0.5
- 0.19 kgf / cm2
7
thickness of thoroughly
weathering areas > 35m,

=
27 - 18
0
, C = 0.25 to 0.17 kgf
/ cm2
9
thickness of thoroughly
weathering areas > 35m,


=
27 - 18
0
, C = 0.25 to 0.17 kgf
/ cm2
9
thickness of thoroughly
weathering areas > 35m,


= 27 - 18
0
, C = 0.25 to 0.17
kgf / cm2
9

7. The flow of
H 7
Siltstone, clay shale Q <0.1L / s 1 Siltstone, clay shale Q <0.1L / s 1 Siltstone, clay shale Q <0.1L / s 1
Terrigenous sediments, 3 Terrigenous sediments, 3 Terrigenous sediments, 3
17

The natural - technical factors in the mountainous areas
from QT to TTH

The natural slope in research
area
The construction sloping roof in
research area

Name
No
tati
on
I
i

Impact intensity level (level
of influence) of the natural
and technical elements
M
ij

Impact intensity level (level
of influence) of the natural
and technical elements
M
ij

Impact intensity level
(level of influence) of the
natural and technical
elements
M
ij

arties Q, l/s
terrigenous - eruption with Q
= 0.11 - 0.25l / s
terrigenous - eruption with Q

= 0.11 - 0.25l / s
terrigenous - eruption with
Q = 0.11 - 0.25l / s
Metamorphic rocks,
terrigenous, intrusion Q =
0.26 - 0.40l / s
5
Metamorphic rocks,
terrigenous, intrusion Q =
0.26 - 0.40l / s
5
Metamorphic rocks,
terrigenous, intrusion Q =
0.26 - 0.40l / s
5
Coarse terrigenous,
terrigenous - carbonate, basalt
with Q = 0.41 - 0.60l / s
7
Coarse terrigenous,
terrigenous - carbonate, basalt
with Q = 0.41 - 0.60l / s
7
Coarse terrigenous,
terrigenous - carbonate, basalt
with Q = 0.41 - 0.60l / s
7
Fractured rock, highly Karst
limestone wth Q> 0.60l / s
9

Fractured rock, highly Karst
limestone with Q> 0.60l / s
9
Fractured rock, highly Karst
limestone with Q> 0.60l / s
9






8. Vegetation
cover

I 7
Thickness of woody forest
vegetation, canopy cover
more than 50%

1
Thickness of woody forest
vegetation, canopy cover
more than 50%

1 - -
Mixed forest with canopy
cover from 50 to 30%
3
Mixed forest with canopy

cover from 50 to 30%
3 - -
Shrubby , reeds, canopy from
30 to 10%
5
Shrubby , reeds, canopy
from 30 to 10%
5 - -
Agricultural cash crops,
canopy cover less than 10%,
forest trees were damaged by
construction
7
Agricultural cash crops,
canopy cover less than 10%
7
Agricultural cash crops,
canopy cover less than
10%, forest trees were
damaged by construction
7
Bare soil, bare hills 9 Bare soil, bare hills 9
Bare soil, bare hills by
construction
9
9. The Deep
cleavage of
topography E
d
,

m/km
2

K 5
E
d
<

50 m/km
2
1 E
d
<

50 m/km
2
1 - -
E
d
= 50 - 250 m/km
2
3 E
d
= 50 - 250 m/km
2
3 E
d
= 50 - 250 m/km
2
3

E
d
= 251 - 450 m/km
2
5 E
d
= 251 - 450 m/km
2
5 E
d
= 251 - 450 m/km
2
5
E
d
= 451 - 650 m/km
2
7 E
d
= 451 - 650 m/km
2
7 E
d
= 451 - 650 m/km
2
7
E
d
> 650 m/km
2

9 - - E
d
> 650 m/km
2
9
The intensity of geo - dynamic K
DDL (SD)
= 39% K
DDL (MD)
= 80.5%
18

Table 6. The mumerical matrix of natural - techinical environment factors on
the moutainous areas from Quang Tri to Thua Thien Hue

4.4.2. Assess the impact intensity level, the risk level of the constituents of
lansslide according to intensity level index and establishment the zoning risk
prediction of lanslide with each factor (scale 1:50000)
On the basis of these data, documents on digital elevation model DEM,
data of rainfalls, main traffic road, geological and lithological map, techtonics
faults map, the weathering crust map and data of shear resistance strenght of
whearthering rock and soil, the flow of arties, vegetation cover, Authors
carried out the construction of partial maps as follows: (1) Slope map; (2) Map
of annual average rainfall; (3) Map of economic – engineering activities
(mainly riad construction), (4) Map of lithological composition, soil structure;
(5) Map of the density of tectonic faults; (6) Map of thickness, the shear
resistance strength of strong wheathering rock; (7) Map of The level of rich
water; (8) Map of vegetation cover; (9) Map of deep cleavage of topography as
shown in Figure 2.












19

Figure 2. The component maps (1-9) and integrated diagrams (10)
20

4.4.3. Integrate all component maps (factors) to build zoning and prediction
map of landslide on slope in the mountainous area from Quang Tri to Thua
Thie Hue with scale 1:50000
The zoning and prediction map of landslide on slope in research area was built
on the basic of the assessment mechanism of moving rock and soil on slope and the
factors causing the landslide rocks were selected and analyzed in thesis (figure 3a,b).
The delimitation of areas not yet affected by affecting factors to landslide
was based on the assumption: The landslides in the future will take place in the
same conditions as the same was happened before. Start from the probability
process, from the similarity of the factors that affect or influence to delineate
the boundaries of risk area of landslide. Therefore, the level of risk quantitative
of landslide as an integreted resutlts of affecting and influencable factors to the
araising of landslide as the following formula:

(i = 1,2,….n; j = 1,2,….m)
In which: LSI: Landslide Susceptibility Index
M
ij
: The intensity value impact (level of influence) of the Jth layer in
landslide factors
W
i
: The important index is attached to the ith component class
n: number of class components are selected for the analysis process
(n = 1,2,3,… 9)
m: level of decentralization in each layer components (m = 1,2,3,4,5 )
The zoning and prediction map of landslide on slope in research area was built
on the principle of stacking and integrated 9 integrated component maps which have
important index with the helping from GIS techonology as following formula:

LSI = 0.2027* a + 0.2027 *b + 0.2027 * c + 0.0724 * d + 0.0724 * e +
0.0724 * g + 0.0724 * h + 0.0724 * i + 0.0302 * k
With a, b, c, d,…, k are component maps (affecting factors)
The process of integrating the component map and calculation important
index for all information layers are encoded into digital format and stacking follow
formula above. The integrated processing results are obtained the digital maps
with each pixels coresponding to a LSI value. The calculation results for LSI in
research area were changed from 1.41 to 6.04. From the series of LSI values, the
method used to assign the automatic switching LSI values follow 5 levels of
landslide in researching area as detailed presentation in Table 7 and figure 3a,b.
Table 7. Decentralization the risk of landslide in the moutainous
area from Quang Tri to Thua Thien Hue
Grouping
Level of
Senitive
Slipped LSI
Area
(km
2
)
Area
ratio
(%)
Level of
sliding
disaster risk
Color on
the map
Senitive
Slipped

Index LSI
< 2.36 1034.0 16.77
Very weak Dark blue
2.36 - 3.29 1778.9 28.85 weak Turquoise
3.29 - 4.22 604.7 9.81 Average Yellow
4.22 - 5.15 2569.5 41.67 Strong Orange
> 5.15 179.6 2.91 Very strong Red
,
, 1
S (W *M )
n m
i i j
i j
L I



21

Figure 3a. The zoning and prediction map of landslide
natural slope
in the research area
from Quang Tri to Thua Thua

Figure 3b. The zoning and prediction map of landslide
construction sloping roof
in the
research area from Quang Tri to Thua Thua Hue
22

Through the zoning and prediction map of landslide in the research area
from Quang Tri to Thua Thua Hue show that:
- For the zoning and prediction map of landslide in the research area from
Quang Tri to Thua Thua Hue without the active participation of roads exist only
2 levels of risk: weak and very weak. This is quite consistent with the status quo
on the hill slopes naturally slide with only 39 points slip intensity geodynamic
activity = 39%.
- Established 5 levels of risk: very strong risk of landslide (2.91%) scattered
distribution in section of West Huong Hoa district of Ho Chi Minh highway and
in Dakrong, A Luoi; strong risk of landslide predominate (41.67%), which
concentrated mainly in the communes of Huong Hoa district, Dakrong district,
Phong Dien district, Huong Thuy district, A Luoi district, Average risk of
landslide (9.81%) concentrated in Huong Hoa district, Dakrong District, Nam
Dong district, weak and very weak risk of landslide predominate 45,62% of the
square of research area which concentrated in Vinh Linh district, Gio Linh
district, Cam Lo district, Trieu Phong district, hai Lang district, Quang Dien
district, Huong Tra district, Huong Thuy district and Phu Loc district.
- The largest density of landslide are about 15-25 sliding blocks per 100
km
2

, which concentrated in Huong Lap commune, Huong Viet commune,
Huong Phung commune, ; The average of sliding blocks are about 10 - 15
blocks per 100 km
2
. And in A Ngo commune, Ta Rut commune, Hong Van
commune, Hong Trung commune, Bac Son commune, Son Thuy commune,
Hong Ha commune, the density of sliding points are lower, about 5 - 10 sliding
blocks per 100 km
2
.
Finally, the distribution range (area) of the levels of landslide risk with the
density of sliding blocks per 100 km
2
corresponding to each level of risk was
established on zoning and prediction map of landslide were quite compatibility
with status monitoring results on really slope. This is also convincing evidence
the intensity of moving rock and soil by gravity on slope that can assess, zoning
and prediction by Mathematics - Mapping model method with the help from
GIS techonology (the second theorotical poit).

CHAPTER 5. PROPOSE THE PREVENTIVE MEASURES
OF THE MOVING ROCK AND SOIL ON SLOPE AND
SLOPING ROOF IN RESEARCH AREA
5.1. General assessment of the effectiveness of preventive measures of the
moving rock and soil by gravity on slope which were applied in research
mountainous area.
The moutainous area from QT to TTH had plenty construction measures
and maintenance as the concrete retaining walls (with or without reinforcing
steel), retaining wall reinforced concrete with pile foundations, gabion wall,
harmoniously combined with cutting solutions offload engine, step slopes, the

top drainage ditches, underground road sewage, sloping water, the processing
solution of groundwater, erosion resistance on surface slope,
In general, preventive measures are on the part of certain effective for
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those each parts. Besides, there are a number of unsuitable measures and there
are surface water drainage works which have not really capable of flood
drainage, slope design steps unreasonable, digging away the soil sliding blocks
to create steps slope calculation should not exhaustive in length, wide slopes
and slope reveal wider, less compacted slope on the surface engineering,
5.2. Propose the preventive measures of moving rock and soil by gravity
on slope and sloping roof in the moutainous area from Quang Tri to Thua
Thien Hue
Non-construction measures are cosmopolitan area and highlights some
specific measures for each sliding positions: management of social - economic;
planning, the reasonable land using; monitoring, prediction the deformation of
slope, tracking, management of the current status of landslide; method of
designing construction, troubleshooting the landslide, maintenance of road.
However, These measures has been applied and deployed after the landslide
occured so they meant the main overcome the consequences, not be long-term
preventive signification. So, the effectiveness of the measures is limited.
The Construction measures have a general principle is used the
constructions and the reinforcement to reduce as much as possible in order to
overcome the main reasons caused the moving of rock and soil on slopr by
gravity, increasing the sliding resistance capability of rock sphere.
In thesis, focus only on the explanation and proposition the strategic
oriented construction measures to prevent from the landslide in critical sections:
concrete retaining walls, concrete retaining wall with reinforced steel, the
concrete retaining wall reinforced with pile foundations, the prestressed anchor,
the gabion wall, harmoniously combined with cutting solutions offload engine,

step slope, the top drainage ditches, underground road sewage, sloping water, the
processing solution of groundwater, erosion resistance on surface slope,
However, due to the characteristics of each area (topographical features with
height more than 800m, slope degrees more than 450 degrees, rainfalls more than
3400 mm per year,the thickness of PH crust more than 35mm, ) as well as owner
that have too many implementations should the disposal of the slide (the big
sliding blocks) were not yet effective. According to the most recent observations
through the the field work showed that among the research moutainous area with
specific areas as mentioned, in the rainy season, most of the surface water
drainage system are not really enough water drainage capacity of rainy season
causing stasis blocked pipe, drains away , break the road or runs off along the
road, causing the negative under-slope, destroying many buildings.
Therefore, with the large and larger scale of sliding points occur
frequently, constantly and repeated from year to year in the rainy season. To
handle and resolve effectively the phenomenon it is necessary to focus on the
processing of rain water, surface water. The most effective and feasible
solutions at present are need to combine plans as follows: Building the sewers
wrap on top road batters like groovers and foot groovers, the sewers, the water
collection pit and build viaducts, help fast drainage, prevent water runoff from
slope to the surface of road batters and take the water flow out of area where
have the risks of landslide.