Study On Stress Mechanism Of Rock And Soil Slopes Supported By Anti-slide Pile

With the rapid development of economic construction,urban construction land is increasingly tense.In order to solve the problem of limited urban land resources development,people have increased the utilization rate of land by building more highrise buildings.As the building volume gradually increases,the slope engineering also moves from shallow excavation and simple support to large Scale and high slope development.The high-slope support structure is often more complicated,the construction difficulty is correspondingly increased,and the engineering accidents such as the instability of the slope are also endless,and the damage is serious.The geological types of high-slopes in mountainous cities such as Chongqing are often composed of two-layer strata of soil-rock combination.Compared with a single soil slope or rock slope,the calculation of geotechnical pressure is relatively complicated.In particular,in order to ensure the safety of existing buildings(structures)on the top of the slope,slope-supporting is often carried out by using anti-slide piles,and construction is carried out according to the reverse method.Under the joint action of the supporting structure and the soil layer and the rock stratum,the geotechnical pressure distribution is more complicated.Based on the existing geotechnical pressure calculation theory,theoretical analysis,numerical simulation and indoor model test method are used to study the distribution law of geotechnical pressure of soil-rock combination slope under antislide pile support,and it is applied in practical engineering application.verification.The main research contents of the thesis are as follows:(1)According to the morphology of bedrock surface,the slope of soil-rock combination is divided into horizontal bedrock slope and inclined bedrock slope.According to the relative relationship between rock formation surface and slope occurrence,the soil-rock combination slope is divided.The rock layer has an outwardly inclined structural surface and a slope without an outwardly inclined structural surface.This paper summarizes the types of earth pressures that may occur in the actual soil-rock combination slope engineering,establishes the geological model of different types of soilrock combination slopes,and based on the existing geotechnical pressure calculation theory to propose the geotechnical pressure calculation method for different types of soilrock combination slopes.(2)Considering the interaction between the supporting structure and the soil layer and the rock stratum,considering the deformation coordination relationship between the rock layer and the supporting pile,the constraint of the lateral displacement of the overburden layer is analyzed.The mechanism of rock pressure generation is analyzed from the angle of rock excavation unloading elastic strain energy release.Under the action of the upper soil pressure,the anti-slide piles have flexural deformation,and the restraining effect of the anti-slide pile on the rock layer is small and large.(3)Using Flac3 D to establish three-dimensional models of different types of soil-rock combination slopes,simulate the excavation process of soil-rock combination slopes according to the reverse construction method,and analyze the variation law of geotechnical pressure during excavation of soil-rock combination slopes..The effects of different soil-rock ratios on the deformation of the slope and the support structure are studied.(4)Based on the principle of similarity ratio,the model test is designed.According to the geometric,heavy and density scales,the physical friction similarity scales such as internal friction angle,cohesion force,stress and strain are obtained.The internal friction angle and density of the soil layer and its similar materials are obtained through laboratory tests.The uniaxial compressive strength standard values of the original rock and its similar materials indicate that the sand is used to simulate the upper soil layer of the slope,and gypsum,barite powder and sand are used.It is reasonable to simulate rock formations with water and other mixtures.(5)According to the similarity principle,the model test of different types of anti-slide piles supporting soil-rock combination slope is designed.The step-by-step excavation test simulates the reverse construction method,and the RFP membrane pressure test system is used to test different types of soil-rock combination slopes.The geotechnical pressure is used to analyze the distribution of geotechnical pressure under different soil-rock ratios and the variation characteristics of geotechnical pressure during excavation.The wedgeshaped rock block is used to simulate the soil-rock combination slope sliding along the camber structure surface,and the influence of the wedge body sliding on the upper soil pressure distribution during the excavation process is analyzed.The inclination angle of the different bedrock surface is simulated by adjusting the inclination angle of the wooden board.The variation law of the upper soil pressure under the condition of the external rock foundation is analyzed.(6)Combine the soil rock combination slope engineering example to analyze the stability of the slope.According to the engineering geological conditions of the slope,the slope is a horizontal rock surface with no excavation structure.Through the on-site reinforced concrete meter and earth pressure gauge,the internal force of the pile body and the distribution of geotechnical pressure are obtained,and the variation law of the geotechnical pressure with the excavation depth is summarized.