Study On The Effect Of Anti-slide Pile For Reservoir Bank Landslide Prevention Under The Action Of Dry And Wet Cycling

The wet and dry cycle is an important factor affecting the evolution of the reservoir bank landslide-anti-slip pile system.The water level in the Three Gorges reservoir area fluctuates between 145-175 m for a long time,and under the influence of periodic reservoir water level fluctuation and rainfall evaporation cycle,the landslide and geotechnical body experience wet and dry cycles for a long time,and the deterioration effect of landslide and geotechnical body varies significantly,thus changing the landslide seepage field and stress field and affecting the landslide-anti-slip pile system prevention and control effect.Therefore,it is extremely important to carry out research on the effect of anti-slip pile support on landslides in the Three Gorges reservoir area under the action of dry and wet cycles.Based on the data collection and site investigation,the distribution characteristics and deformation of Shilongmen landslide are analyzed,the indoor physical property test is conducted for the soil around the anti-slip pile,and the triaxial test is carried out under the action of dry and wet cycles to investigate the influence law and mechanism of the soil around the pile under the action of dry and wet cycles.On this basis,the physical model of Shi Longmen landslide-anti-slip pile support system was built to investigate the effect of dry and wet cycling on the anti-slip pile support of the reservoir bank landslide management under real environmental and climatic conditions,and to reveal the evolution of the landslide-anti-slip pile support system.The evolution characteristics and destabilization mode of the landslide-anti-slip pile support system are revealed.Finally,based on the numerical simulation,a numerical simulation scheme of the anti-slip pile support system under the action of dry and wet cycles is proposed,and the simulation calculation is compared with the model test to verify the conclusions.The main research results and conclusions of this paper are as follows.(1)The surface damage characteristics of soil samples under the action of dry and wet cycles can be divided into two damage forms,soil spalling form and surface cracking form.In the process of wet and dry cycles,the temperature causes the soil particles to shrink and swell continuously,and the water molecules will continuously penetrate into the soil sample,which will cause more and more damage to the soil,resulting in a very poor surface integrity of the soil sample.(2)The shear strength of soil samples gradually decreases with the increase of wet and dry cycles,and the cohesion of soil samples decreases with the increase of the number of wet and dry cycles.The slope of the correlation curve decreased with the increase of the number of wet and dry cycles,and the initial wet and dry cycles caused the greatest damage to the soil samples.(3)The influence of the soil around the pile after wet and dry cycling on the effect of anti-slip pile support.Under the conditions of extreme rainfall and repeated rise and fall of the reservoir water level,the dry and wet cyclic state of evaporation and drying of the soil around the anti-slip pile after full water absorption and saturation is very unfavorable to the support of the anti-slip pile,and the relevant conclusions drawn from the test are consistent with the reality.(4)Based on the physical model test,the evolution characteristics of the landslideanti-slip pile support system are revealed by the rise and fall of the reservoir water level and the evaporation cycle of rainfall.After the reservoir water level rise and fall and rainfall evaporation cycle,the rock and soil parameters around the pile will decrease,resulting in the weakening of soil arch effect and the decrease of anti-slip pile support effect;under the fluctuation condition of reservoir water level cycle,the deformation of the front edge of the slope body will be larger,which will continuously promote the spalling deformation or traction deformation of the front edge of the slope body to a larger extent,and along with multiple reservoir water level cycles and rainfall evaporation,the soil of the slope body will be continuously scoured and softened,and the stability of the slope body will decrease.The stability of the slope will be reduced and the effect of anti-slip pile support will be affected.(5)Based on the displacement monitoring and macroscopic deformation characteristics,the relative motion law and destabilization process of the reservoir bank landslide-anti-slip pile support system were revealed.The process profile of the rapid rise of slope displacement during the cycle of reservoir water level rise and fall and rainfall evaporation is divided into displacement initiation stage,slope creep and slip stage,displacement acceleration stage,and displacement change flat stage.In the displacement acceleration stage,cracks appear in the soil body behind the pile,and the slope body is considered to be in an unstable state at this time.(6)When managing the landslide body,it is necessary to pay attention to the local area around the anti-slip pile while starting from the whole slope body.The local area of the slope body soil parameters decline and the formation of cracks in the region,will greatly reduce the effect of the nearby anti-slip pile support,and at the same time also affect the effect of other areas to play a role in the anti-slip pile support,and this is determined by the anti-slip pile support mechanism,anti-slip pile is a passive pile,can only passively withstand the thrust from the upper part of the landslide,the thrust will make the soil arch effect increase the soil crowding,if If the cracks in the area are allowed to penetrate,it will cause the nearby anti-slip piles to fail,and also cause the soil around the piles in other areas to be sheared out from the top,and the soil arch effect of the anti-slip piles will fail,which greatly affects the overall anti-slip pile support effect.