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 (tóm tắt + toàn văn)

- Research on the moving rock processes in the mountainous area from Quang Tri to Thua Thien Hue.. - Proposition the classification of the moving rock on slope in the mountainous areas

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

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

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

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

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 1st 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 2nd 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

- 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

15th to 18th century, began to develope deeper and wider in the 19th century and reached the peak in the 20th 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

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 29th, 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

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 - O1av), Long Dai (O3 - S1lđ),

Dai Giang (S2 - D1dg), Tan Lam (D1 tl), Co Bai (D2-3 cb), La Khe (C1lk), Bac

Son (C - Pbs), A Lin (P ? al), Cam Lo (P2cl), A Ngo (J1 an), Mu Gia (K2mg),

Neogene (N) and Quaternary (Q)), 10 instructive magma complexes (Hiep Duc

O-Stb), Dai Loc (GaD1Ddl), Ben Giang - Que Son (GDi-G PZ3bg- qs), Chaval

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, IA1, IA2, 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

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,

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

3 The West branch of HCM highway

from Quang Tri to TT- Hue 322 26

4 Highway No.49 and nearly mountainous

5 Highway No.49B and neighboring areas 8 1

6 Highway No.1A and neighboring areas 7 2

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

soil from 1.79 - 1,99 g/cm3 in dry seasonand in the wet season it can be reached 1.87 - 2,05 g/cm3 Besides, these two parameters, which are φ and C of wreak slope soil, declined strongly; In natural state, φ = 20 - 250 and C = 0.23 - 0.30 kG/cm2 and

in water-saturated, φ = 18 - 220 and C = 0.14 - 0.25 kG/cm2 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 /cm2, φ

= 35 - 490 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/cm2 and φ = 23 -

280, 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

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 + IA1) 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 - 200, C = 0.75 - 0.1kG/cm2

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 26 260 to 450 and more 450

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

3.3.3 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

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

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

Rockfall is about 50 meters volumeat 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

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

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