Stability Analysis And Stabilizing Pile Treatment Study Of Hetaoping Landslide

Taking the Hetaoping landslide in Maoxian County for example,a detailed study on its geological characteristics was conducted herein based on data collection and field investigation.Then,the stabilities of the landslide under natural,heavy rain and seismic conditions were analyzed using the limit equilibrium theory and numerical simulation.After that,the support effects of different composite modes of stabilizing piles at a heavy rain condition were simulated and compared with the optimal composite mode of stabilizing piles being reached.Finally,the optimal composite mode of stabilizing piles was used to the prevention of the landslide with an economic and reasonable control scheme being proposed.And a prefect result is achieved which satisfies the requirement for the landslide treatment.The main conclusions of this study are as follows.(1)Based on a detailed study of the geological characteristics of the Hetaoping landslide,it is reached that the Hetaoping landslide is a large-sized bedding landslide with great deformation and potential hazard.Due to the effect of the Wenchuan earthquake,buildings on the landslide slope have been destroyed severely.And tensioning cracks are developed in the middle and rear parts of the landslide,indicating the occurrence of local failures.Under a heavy rain condition,rainfall can seepage into the landslide easily along these cracks and induces great decreases of the related physical and mechanical parameters of the soil.Therefore,analysis on the stability of the landslide is urgent and necessary.(2)Using the limit equilibrium theory and FLAC3 D simulation,the stabilities of the landslide under natural,heavy rain and seismic conditions were analyzed quantitatively.It is reached that the landslide is stable in natural condition.In the heavy rain and seismic conditions,the stabilities of the east and middle parts of the landslide will decrease obviously with the middle part decreased severest.The west of the landslide is relatively stable.This result is consist with the field investigation.Analysis on the effects of c and ? on the stability of the landslide reveals that the landslide safety factor is more sensitive to the variation of ?.(3)Through a series of simulation and analysis of the effects of different composite modes of stabilizing piles on the stability of the landslide,it is reached that:(1)Arranging stabilizing piles in the middle and lower parts of the landslide is advantage for the stability of the landslide.(2)Decreasing stabilizing pile spacing can improve the stability of thelandslide.But the engineering cost will increase significantly.So,it is reached that the optimal pile spacing is 4m~6m in this study.(3)As the increase of the size of stabilizing pile section,larger landslide-thrust will be born by the pile.Meanwhile,the displacement of the landslide will decrease with the landslide stability improved significantly.But,the increase of the size of stabilizing pile section will increase engineering cost.So,values of1.5m×1.0m and 2.0m× 1.5m are proposed as the optimal sizes of pile section in this study.(4)The larger the stabilizing pile built-in depth is,the larger the bearing capacity of the stabilizing pile on landslide-thrust and the higher the stability of the landslide.But,as the increase of the stabilizing pile built-in depth,the operational difficulty and engineering cost will increase significantly.So,it is reached that the optimal pile built-in depth is 0.25 L in this study.(4)Based on the study of the support effects of different composite modes of stabilizing piles,both support schemes were proposed firstly.And then,through a comparison of both support schemes,the first scheme featured by non-equal section sizes and non-equal pile spacing was select for the prevention of the landslide.And a further optimization of the first scheme was conducted according to the spatial distribution of the landslide-thrust.It is reached that the optimized mode of the stabilizing piles can improve the stability of the landslide significantly,which indicates that the use of stabilizing piles featured by non-equal section sizes and non-equal pile spacing is advantage for the landslide prevention and the reduction of engineering cost.