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: Assoc Prof Dr Ta Duc Thinh, Ministry of Education and Training 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 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 geodynamic 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 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 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 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 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; 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 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 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 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 Main basics of references The thesis was accomplished by all documents which were collected through 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 chapters and illustrated by 12 maps, 34 datasheets, figures and charts, 18 pictures, table appendixes, 44 picture appendixes; With publishing scientific journals and 110 catalogs of reference Chapter 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 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 to rains extend from days to days, individual, somtimes can be to 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-  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 - P bs), 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 PZ1hd), Nui Ngoc (GbPZ1nn), Dieng Bong (GPZ1db), Tra Bong (Di - GDi OStb), Dai Loc (GaD1Ddl), Ben Giang - Que Son (GDi-G PZ3bg- qs), Chaval (GbaT3cv), Hai Van (GaT3hv), Ba Na (GE2bn), Mang Xim (SyE2mx) ), 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, 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 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 The main traffic routes from Quang Tri to TT - Hue Sloping Order Locations Slopes Roofs Highway No.9 and nearly mountainous 16 are Vinh Khe - Cam Lo (West part of HCM highway) The West branch of HCM highway 322 26 from Quang Tri to TT- Hue Highway No.49 and nearly mountainous 19 area Highway No.49B and neighboring areas Highway No.1A and neighboring areas 381 39 Total 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 60 R < 2200 mm/year R = 2200 - 2600 mm/year R = 2601 - 3000 mm/year R = 3001 - 3400 mm/year R > 3400 mm/year The distance to traffic road more than 2000m The distance to traffic road from 2000m to 1000m The distance to traffic road from 1000m to 500m The distance to traffic road from 500m to 200m The distance to traffic road less than 200m Structure of rock blocks , very thick layered more than 1.0m Rock layered with layer thickness from1.0 to 0.2m Thin bedded rock, slate feces from 0.2 to 0.01m rock slate feces (thin slate Mij 9 The natural slope in research area Impact intensity level (level of influence) of the natural Mij and technical elements  < 15  = 15 - 300  = 31 - 450 = 46 - 60  > 600  R = 2200 - 2600 mm/year R = 2601 - 3000 mm/year R = 3001 - 3400 mm/year The distance to traffic road more than 2000m The distance to traffic road from 2000m to 1000m The distance to traffic road from 1000m to 500m Structure of stone blocks , very thick layered more than 1.0m Rock layered with layer thickness from1.0 to 0.2m Thin bedded rock, slate feces from 0.2 to 0.01m rock slate feces (thin slate The construction sloping roof in research area Impact intensity level (level of influence) of the Mij natural and technical elements = 46 - 600   > 60 R < 2200 mm/year R = 2200 - 2600 mm/year R = 2601 - 3000 mm/year R = 3001 - 3400 mm/year R > 3400 mm/year - - The distance to traffic road from 500m to 200m The distance to traffic road less than 200m Structure of stone blocks , very thick layered more than 1.0m Rock layered with layer thickness from1.0 to 0.2m Thin bedded rock, slate feces from 0.2 to 0.01m rock slate feces (thin slate 16 The natural - technical factors in the mountainous areas from QT to TTH Name The density of tectonic faults D2f, km/km Thickness, the shear resistance strength of rock in strong and ompletely subsidiarity weathering The flow of No tati on E G H Ii 7 Impact intensity level (level of influence) of the natural and technical elements less than 0.01m) Uncohension and2soft soil Df < 0.15 km/km Df = 0.15 - 0.30 km/km2 Df = 0.31 - 0.45 km/km2 Df = 0.46 - 0.60 km/km2 Df > 0.60 km/km2 Strongly weathered areas and totally thickness less than 5m with  = 35 - 270, C = 1.5 0.25 kG/cm2 are popolar Strongly and completely weathered areas and totally thickness from 5m to 15m with  = 34 - 260, C = 1.0 0.23 kG/cm2 are popolar Strongly PH area completely thickness 15.1 25m, = 32-230, C = 0.75 0:21 kgf / cm2 Strongly PH area completely thickness 25.1 35m,  = 30 - 200, C = 0.5 – 0.19 kgf / cm2 thickness of thoroughly weathering areas > 35m,  = 27 - 18 0, C = 0.25 to 0.17 kgf / cm2 Siltstone, clay shale Q 0.60 km/km2 Strongly weathered areas and totally thickness less than 5m with  = 35 - 270, C = 1.5 0.25 kG/cm2 are popolar Strongly and completely weathered areas and totally thickness from 5m to 15m with  = 34 - 260, C = 1.0 0.23 kG/cm2 are popolar Strongly PH area completely thickness 15.1 - 25m, = 32-230, C = 0.75 0:21 kgf / cm2 Strongly PH area completely thickness 25.1 - 35m,  = 30 - 200, C = 0.5 0.19 kgf / cm2 thickness of thoroughly weathering areas > 35m,  = 27 - 180, C = 0.25 to 0.17 kgf / cm2 Siltstone, clay shale Q 0.60 km/km2 Strongly weathered areas and totally thickness less than 5m with  = 35 -2 270, C = 1.5 - 0.25 kG/cm are popolar Strongly and completely weathered areas and totally thickness from 5m to 15m with  = 34 - 260, C = 1.0 0.23 kG/cm2 are popolar Strongly PH area completely thickness 15.1 25m, = 32-230, C = 0.75 0:21 kgf / cm2 Strongly PH area completely thickness 25.1 35m,  = 30 - 200, C = 0.5 - 0.19 kgf / cm2 thickness of thoroughly weathering areas > 35m,  = 27 - 180, C = 0.25 to 0.17 kgf / cm2 Siltstone, clay shale Q 0.60l / s Thickness of woody forest vegetation, canopy cover more than 50% Mixed forest with canopy cover from 50 to 30% Shrubby , reeds, canopy from I 30 to 10% Agricultural cash crops, Vegetation canopy cover less than 10%, cover forest trees were damaged by construction Bare soil, bare hills Ed < 50 m/km2 The Deep Ed = 50 - 250 m/km22 cleavage of topography Ed, K Ed= 251 450 m/km2 Ed = 451 650 m/km m/km2 Ed > 650 m/km The intensity of geo - dynamic Name No tati on Ii The natural slope in research area Impact intensity level (level of influence) of the natural Mij and technical elements terrigenous - eruption with Q = 0.11 - 0.25l / s Metamorphic rocks, terrigenous, intrusion Q = 0.26 - 0.40l / s Coarse terrigenous, terrigenous - carbonate, basalt with Q = 0.41 - 0.60l / s Fractured rock, highly Karst limestone with Q> 0.60l / s Thickness of woody forest vegetation, canopy cover more than 50% Mixed forest with canopy cover from 50 to 30% Shrubby , reeds, canopy from 30 to 10% Agricultural cash crops, canopy cover less than 10% 9 Bare soil, bare hills Ed < 50 m/km2 Ed = 50 - 250 m/km22 Ed= 251 - 450 m/km2 Ed = 451 - 650 m/km KDDL (SD) = 39% - Mij The construction sloping roof in research area Impact intensity level (level of influence) of the Mij natural and technical elements terrigenous - eruption with Q = 0.11 - 0.25l / s Metamorphic rocks, terrigenous, intrusion Q = 0.26 - 0.40l / s Coarse terrigenous, terrigenous - carbonate, basalt with Q = 0.41 - 0.60l / s Fractured rock, highly Karst limestone with Q> 0.60l / s - - - - - - Agricultural cash crops, canopy cover less than 10%, forest trees were damaged by construction Bare soil, bare hills by construction Ed = 50 - 250 m/km22 Ed= 251 - 450 m/km2 Ed = 451 - 650 m/km Ed > 650 m/km KDDL (MD) = 80.5% 9 18 Table 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 19 Figure 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: n,m LSI   (W *M i ij ) (i = 1,2,….n; j = 1,2,….m) In which: LSI: Landslide Susceptibility Index Mij: The intensity value impact (level of influence) of the Jth layer in landslide factors Wi: 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 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 levels of landslide in researching area as detailed presentation in Table and figure 3a,b Table Decentralization the risk of landslide in the moutainous area from Quang Tri to Thua Thien Hue Level of Level of Area Area Color on Grouping Senitive ratio sliding (km ) the map Slipped LSI (%) disaster risk i , j 1 Senitive Slipped Index LSI < 2.36 2.36 - 3.29 3.29 - 4.22 4.22 - 5.15 > 5.15 1034.0 16.77 Very weak 1778.9 28.85 weak 604.7 9.81 Average 2569.5 41.67 Strong 179.6 2.91 Very strong Dark blue Turquoise Yellow Orange Red 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 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 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 , which concentrated in Huong Lap commune, Huong Viet commune, Huong Phung commune, ; The average of sliding blocks are about 10 - 15 blocks per 100 km2 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 - 10 sliding blocks per 100 km2 Finally, the distribution range (area) of the levels of landslide risk with the density of sliding blocks per 100 km 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 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 23 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 24 CONCLUSION AND PROPOSAL Conclusion The movements of rock and soil on step slopes in moutainous region from Quang Tri to Thua Thien Hue occur and process strongly in available conditions by not only geological structures but also topography conditions Mostly of landslides appeared in continent sedimentary formation, metamorphism rock (make up 87,4%) which were belong to A Vuong formation (25,7%), Long Dai formation (23,1%), A Lin (14,5%), Tan Lam (11,4%), Ben Giang - Que Son (10,2%), the lanslides often concentrated primarily on steep slopes which have ange of slope from 31 degrees to 60 degrees (59,5%), the thick of wheathering layer is popular from 15,1 meters to 35 meters (81,6%), the mostly kind of landslides in research area are about 224 points and make up 53,4% The impacts of economic - engineering acts and highly rainfall, which extend frequently on many day were two main causes of almost processes on slope In the floody season, lanslide occurred powerfully on slope when the avarage rainfall per year from 2200 milimeters per year to equal or more 3400 milimeters per years (89,8%), and the locations which are effected by economic - engineering acts were about 41,1% In the mountainous areas from Quang Tri to Thua Thien Hue, lanslide was growth mainly on construction slope (381 points, about 90,71%) with the intensity of landslide from strong to very strong (KDDL= 80.5%); Toward the ridge and hillside ( 31 points, about 9,29%) with the intensity of soft soil (KDDL= 39%); The kind of the movement of rock and soil on slope in the mountainous areas from Quang Tri to Thua Thien Hue include two kinds: The movement of homogeneous rock ( Rockfall, landslide, debris flow and rock depression) and the movement of Complex rock In the total of the movement points which were counted that lanslide prevailed with 53.4%, depression (30.4%), debris flow (15%) and rockfall (5%) The formation and development of lanslide phenomenon in the mountainous areas from Quang Tri to Thua Thien Hue were mainly belong to nine natural - human elements The Evalution, prediction and zoning the intensity of lanslide on slope in research area belong based on Zoning and Prediction Map of Lanslide that were established by arranging and integrating nine component maps which have index was determined by space analysis method in GIS with the support by ArcGis software 10.0 According to Zoning and Prediction map of landsslide in the mountainous areas from Quang Tri to Thua Thien Hue, we can establish areas coressponding to dangerous lanslide levels: very strong (2,91%), strong (41,67%), medium (9,81%), weak and too weak (45,62%) with the average density of slide blocks from 10 to 15 blocks per 100 square kilometers The prevention and mitigation measures of lanslide on slope in research area which be selected and proposited base on the objective of uneffectives and inadequate from many preventive construction and consider specifically all 25 elements about the construction importance, practicalbility, the economic techinical efficiency of measures; In each of them, note all simple measures but still ensure the safety and effectiveness Proposal Need to adjust , supplement and apply vivaciously hierarchy level of the decentralization of effective natural - technical factors with the processes of moving rock and soil on slope and sloping roof o suit each specific area, then apply widely used in the mountainous area of the Central Part of Vietnam Need to be more specific about the verification methodologies for the establishment of the zoning and prediction map of landslide on slope in the mountainous area from Quang Tri to Thua Thien Hue For the areas located on the warning level of the risk of landslide from strong to very strong need to buid the warning risk map with scale and more detail In addition to non-structural measures, depending on geological characteristics, lying down of sliding surface or the moving area, the positions of aquifers, water bearing zones and their supply conditions, physical and mechanical properties of rock and soil structured slope and sloping roof of the moving blocks that can be select and deploy the combination of construction measures to solve situations (temporarily) in cheap and fast execution, semipermanent buildings with the investment funding from low to moderate and the landslide still occur during adverse weather conditions; Permanent treatment works which requires high investment cost and ensure stability in all weather In addition, need to build an overall strategy and prevention of moving rock and soil in the mountainous area from Quang Tri to Thua Thien Hue 26 Catalog of Scientific publishing projects Nguyễn Thị Thanh Nhàn, Nguyễn Thanh, Đỗ Quang Thiên (2008), “Ứng dụng phương pháp tiếp cận đa tiêu đánh giá cường độ lũ bùn đá lãnh thổ đồi núi bị chia cắt mạnh tây A Lưới”, Tuyển tập báo cáo hội nghị khoa học lần thứ 18, Quyển 3, Đại học Mỏ Địa chất, Hà Nội, tr.80-86 Nguyễn Thị Thanh Nhàn, Nguyễn Thanh (2010), “Hiện trạng (DCĐĐ) SD dọc tuyến đường HCM đoạn từ Quảng Trị (nhánh Tây) - Thừa Thiên Huế”, Tạp chí Khoa học kỹ thuật Mỏ - Địa chất số 32, Đại học Mỏ - Địa chất, Hà Nội Nguyễn Thị Thanh Nhàn, Nguyễn Thanh, Tạ Đức Thịnh (2011), “Vận dụng lý thuyết phương pháp tiếp cận đa tiêu để đánh giá cường độ hoạt động trượt đất đá vùng đồi núi Tây Thừa Thiên Huế”, Tạp chí Khoa học Đại học Huế, chuyên san khoa học tự nhiên, tập 65, số 2/2011, tr 147-157, Huế 6/2011 Nguyễn Thị Thanh Nhàn, Nguyễn Thanh, Tạ Đức Thịnh (2011), “Thiết lập đánh giá cường độ hoạt động trượt đất đá vùng đồi núi Tây Thừa Thiên Huế phương pháp tiếp cận đa tiêu”,Tạp chí KHKT Mỏ - Địa chất số chuyên đề kỷ niệm 50 năm thành lập Bộ mơn Địa chất cơng trình, số 35 tháng 7/2011, tr24 - 31 Hà Nội, 2011 Nguyễn Thị Thanh Nhàn, Nguyễn Thanh (2012), “TCCL đất đá ảnh hưởng chúng đến trình DCĐĐ SD, MD vùng đồi núi Quảng Trị - Thừa Thiên Huế”, Tạp chí Khoa học, ĐHH, chuyên san khoa học tự nhiên, tập 74B, số (2012), tr 123 - 132 Huế 2012 Nguyễn Thị Thanh Nhàn, Đỗ Quang Thiên, Nguyễn Thanh, Tạ Đức Thịnh (2012), “Phân vùng dự báo cường độ hoạt động TLĐĐ SD vùng đồi núi Quảng Trị - Thừa Thiên Huế phương pháp mơ hình tốn - BĐ với trợ giúp công nghệ GIS”, Tạp chí Khí tượng thuỷ văn số 621, tháng 9/2012, trang 36 - 44 Cao Thị Thúy Vân, Nguyễn Thị Thanh Nhàn, Hồng Ngơ Tự Do, Trần Thanh Nhàn, Đỗ Quang Thiên (2013), “Thành lập đồ phân vùng nguy trượt lở đất đá huyện đồi núi Tiên Phước, tỉnh Quảng Nam” , Tạp chí Khoa học, Trường Đại học Quảng Nam, ISN 0866 - 7586, chuyên san khoa học tự nhiên, số 3(2013), tr 110 - 120 Nguyen Duc Ly, Nguyen Thanh, Nguyen Thi Thanh Nhan and Ta Duc Thinh (2012), “Increase of landslide under the context of climate change in mountainous areas of Binh Tri Thien provinces”, Proceeding of the International Workshop - Hue Geo - Engineering 2012, p 40 - 46 Hue 2012 Tran Huu Tuyen, Nguyen Hoang Son and Nguyen Thi Thanh Nhan (2012), “Application of sinmap terrain stability model in the highways, Thua Thien Hue, Viet Nam”, Proceeding of the International Workshop - Hue Geo Engineering 2012, p 239 - 247 Hue 2012 27 ... 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. .. 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. .. 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