| The Xinjiang Uygur Autonomous Region is an important gateway for China to open to the west,and also an important channel for Asia and Europe.For a long time,due to the complex engineering geological problems in Tianshan mountain area,such as the undulating topography,sharp temperature changes,Freeze-thaw damage and the earthquake prone areas etc,which cause no efficient and direct highway through the whole region from the north to the South of Xinjiang.Among these problems,the mechanism of freeze-thaw weathering failure is a key reason for the highway rock slopes,which is not clear leading to the positioning?project quantity and investment estimation of the highway cannot be accurately evaluated,and the highway construction will be greatly affected.The highway linking Urumqi-YILI is the most convenient transportation.This thesis based on this project,extract the freeze-thaw weathering slope as a research object,on the basis of sufficient geological survey to analyze the natural geographical and meteorological conditions,summarize the law of the slope deformation and failure,extract the main influencing factors of the slope failure,taking of retrieval and laboratory test to study the physical and mechanical characteristics of rock mass under the freezing-thawing condition,using the original data in the field to investigate the freeze-thaw weathering damage of rock mass and rock slope.by Numerical simulation,analysis the rock failure under cyclic freeze-thaw condition,analysis the temperature field?stress field and deformation field,we propose the quality evaluation system of freeze-thaw weathering slope rock mass on the WU-YU highway,which provides technical support for stability evaluation of mountain road slope under complex conditions.Through the research of this paper,the following research results are obtained:(1)Based on the frequent geological disasters,complex climates,broken rock mass and strong weathering in the Tianshan mountain area,we analyzed and revealed that the controlling factor of the freeze-thaw slide failure in Tianshan mountain area under complex conditions is climate condition,the promoting factors are the hydrogeological condition and the surface water,the basic conditions are the topography and rock structure.(2)Based on the detailed investigation and statistics of the topography,geological structure,formation lithology and the bad geology along the route,we divided the engineering geological zones of the highway linking Urumqi and YULI corridor into 2 primary zones,9 secondary zones and 25 tertiary zones.Taking the line density as the index,we studied the development degree of the slope,the sections with high density of the slope development accounted for 51.7% of the total mileage.The main type of the slope failure are collapse,followed by landslide,among them,the type of collapse destruction include the Horizontal unloading rebound+freeze-thaw weathering steep slope collapse,the flake to collapse by the freeze-thaw weathering along the crack surface,the slippage to collapse by the freeze-thaw weathering and the fall to collapse by the freeze-thaw weathering etc.Landslide damage mainly includes large landslides,medium landslides and small landslides and the last two are main landslides.The slope failure initiating factor in this area is the freeze-thaw weathering.(3)By searching the domestic and overseas different rock mass freezing-thawing tests,summarize the changes of physical and mechanical properties of rock and soil under cyclic freezing-thawing conditions,refine the physical and mechanical properties of rock and soil show a tendency of deterioration after cyclic freezing-thawing.According to the special meteorological,geological conditions and research purposes of the study area,we conducted experiments on water ice phase change stress,deformation during frost heave of fractured rock mass and freeze-thaw cleavage of fractured rock mass,which revealed that the failure mechanism of rock mass under freezing-thawing condition should include two aspects: microcosmic rock weathering and macroscopic rapid weathering of rock fractures,among them,the microcosmic rock weathering is caused by thermal expansion and shrinkage at different temperatures in the rock,and the macroscopic rapid weathering of rock fractures is caused by the rapid weathering of the material in the rock structure surface and the water in the crack becomes ice,resulting in the expansion and deformation.The failure of rock structure surface is the main aspect of rock mass freezing-thawing failure.(4)Based on the observation in the field,we analyzed that the freeze-thaw failure characteristics of rock mass with different volumes?different structures and fractures with different lengths in the study area under natural conditions,revealed the reason of rock mass freezing-thawing failure.The freeze-thaw weathering characteristics of intact rocks are closely related to the composition of rock particles?bonding state and texture.At the same time,the freeze-thaw weathering of rock is affected by the water content,temperature range and freeze-thaw time of rock.The feature of the freeze-thaw failure of intact rock is flaking failure.The freeze-thaw weathering rate of the structural rock and the rock mass slope varies greatly,in which the weak surface,such as crack surface and bedding zone is first freeze-thaw weathering.The freeze-thaw failure of homogeneous rock mass slope is gradual peeling from the surface to the center.The freeze-thaw weathering rate of the rock slope with long joints,fracture zones and faults is anisotropic.The macrostructure has strong freeze-thaw guidance.(5)Through the ANSYS thermal module we simulated and analyzed the temperature field of rock mass under different temperature conditions.and the fracture failure of rock under thermal stress and compressive stress.The thermal stress caused by cyclic freezing and thawing changes the gravity field of slope and caused the local stress concentration in the slope rock mass.Especially the large cracks with fissure water,in which the concentrate stress is sufficient to split the rock mass.(6)In order to better reflect and apply the characteristics and rules of the freeze-thaw weathering in the project,this paper extracted the main factors influencing the stability of the freeze-thaw weathering slope.Based on the basic quality system of rock mass BQ,combined with the development characteristics of slope and the modification of the influence on groundwater,this paper constructs the quality evaluation system of rock mass of slope TBQ,which take into account the rock strength,rock mass integrity,slope structure and the influence of water.The aim of rapid,accurate and economic evaluation of the slope rock mass is achieved.On this basis,The stability prediction system of slope rock mass TFBQ was constructed by modifying the factors of the freeze-thaw weathering,earthquake and excavation,which systematically evaluated the stability and development trend of slope in the study area,and revealed the influence of freeze-thaw weathering on slope.This study provides a technical basis for the slope protection design of this project. |
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