Stability Analysis And Anti-slide Pile Treatment Study Of Gaojiafangji Landslide

Taking Gaojiafangji landslide in Zijing Village,Tiantaishan Town,Qionglai City as the research object,and conducts a detailed study on the engineering geological conditions of the landslide area and the current deformation and failure characteristics through field investigation and data collection.Then,analyze and evaluate the deformation and failure modes and stability of landslides under natural,heavy rain and earthquake conditions from the theoretical analysis and numerical simulation.Finally,based on the results of the stability analysis,the reasonable design values of the main design elements of the anti-slide pile are optimized through numerical simulation;Propose anti-slide pile treatment plan,optimize the plan considering the lateral deformation characteristics of the sliding body and economic benefits,and apply it to the main model of landslide to evaluate the treatment effect.In order to determine a more effective and economic treatment plan,it can provide reference for the design of Gaojiafangji landslide treatment project.The main conclusions are as follows:(1)The Gaojiafangji landslide is a medium-sized overburden soil landslide.The landslide and the ridges on both sides form a trough-type water catchment terrain.The landslide is steep and gentle on the whole,and the trailing edge is obviously chair-shaped.The cracks on the landslide body are well developed,and the upper part is obviously deformed.Under the effect of rainfall,local collapse has occurred,and the front edge of the landslide has bulging deformation.The deformation failure mode is a typical push-type sliding.The stability of landslides is affected by both internal factors and external factors.Among them,rainstorms and earthquakes are the main external factors of landslides.At present,the overall stability of the landslide is poor,and it is extremely prone to overall deformation and damage under the action of heavy rain and earthquakes.(2)The calculation result of the stability of the Gaojiafangji landslide based on the transfer coefficient broken line method shows that the landslide is basically stable in the natural state.Unstable under heavy rain.Once subjected to extreme environmental factors,the landslide is very easy to start,and the overall deformation and destruction occur.Through horizontal comparison of the stability results of different calculated sections,the stability on the right side of the landslide body is the worst,while the middle and the left are the second.(3)The deformation failure characteristics and stability results based on FLAC3 D numerical simulation method show that the deformation failure modes of landslides in different states are all sliding.The deformation and failure of landslides are affected by the topography and topography,and the lateral deformation is significantly different.This is more consistent with the conclusion drawn by the transfer coefficient polyline method.In the natural state,the overall stability is better.Only a small area of local collapse exists on the upper part of the sliding body,and the overall sliding will not occur.In the rainstorm state,the cracks on the trailing edge of the downhill slope expand,the upper load increases rapidly,and the shear deformation of the upper part quickly expands to the lower part,causing overall deformation and sliding.The dynamic response characteristics of the landslide under seismic load indicate that the deformation of the landslide shows a wave growth without instantaneous large-scale deformation failure.Tensile deformation mainly occurs in the upper part of the landslide,and shear deformation mainly occurs in the middle and lower part.If the landslide is continuously affected by the seismic load,it will easily induce overall instability.(4)The full-length anti-slide piles are selected to control the landslide,and the enumeration method is used to conduct a numerical simulation study on the main design elements of the anti-slide piles based on the single variable principle.(1)When the pile position moves from the lower part to the upper part of the landslide,the stability of the landslide increases first and then decreases.When the anti-slide piles are installed in the middle and upper part of the landslide,the soil in front of the piles and the piles in the limit state can reach the plastic state together,and the shear strength of the landslide soil can be fully exerted.This is consistent with the sliding failure mode of Gaojiafangji landslide deformation,where piles can reduce the overall deformation of the landslide.(2)The smaller the spacing between anti-slide piles,the higher the landslide safety factor.As the distance between the piles increases,the most dangerous sliding surface of the soil in front of the pile is gradually connected with the most dangerous sliding surface of the soil behind the pile.Considering comprehensively the effectiveness and economy of treatment,the reasonable range of pile spacing is 5 m.(3)The greater the anchoring depth of the anti-slide pile,the higher the safety factor of the landslide.However,the effect of increasing the anchoring depth to improve the stability of the landslide is not unlimited.When the anchoring depth is increased to a certain depth,the safety factor of the landslide will remain stable.Comprehensively considering the effectiveness and economics of treatment,the anchoring depth is determined to be 2/5 of the pile length.(4)Based on the optimization results of the main design elements of anti-slide piles,a landslide treatment plan with anti-slide piles at equal intervals is proposed.Taking into account the lateral deformation characteristics of the landslide and the economics of treatment,the treatment plan is optimized with unequal spacing.The plan before and after optimization is applied to the main landslide model to test its treatment effect.The results show that the scheme before and after optimization can play a good role in strengthening the landslide.It proves that it is feasible to optimize the original design scheme with unequal spacing,which can not only effectively improve the stability of the landslide,but also reduce the cost of landslide treatment.