Study On Soil Arching Effect Of Combined Double-row Piles

With the recovery of economic construction and the rapid development of highway construction,as well as the influence of many natural factors such as the existing traffic facilities,the geological disasters of highway slope and surrounding mountains show an increasing trend year by year.Because the construction of anti slide pile is simple and the retaining effect is good,in the face of the large-scale landslide which has a great impact on people’s safety and economy,people generally use the combined anti slide pile for treatment.However,the passive pile-soil arching effect can not be observed by scientific instruments,and the factors affecting the soil arching effect of anti slide pile are very complex,which leads to the disunity of the application and theoretical research of combined anti slide pile,resulting in the over conservative design of this kind of supporting structure,excessive performance,and indirect economic waste.Therefore,the research on soil arching effect of combined double row anti slide pile has good economic value and engineering application significance.Based on the above background,through the theoretical research,numerical simulation research and experimental research,from the whole to the local,from the macro to the micro,this paper studies and analyzes the development failure process of soil arching effect and the influence of related factors on soil arching effect,and draws relevant conclusions.(1)The mechanical analysis model of combined double row pilesIn the aspect of theoretical research: through reasonable assumptions,a simplified pile-soil mechanical calculation model of combined double row piles is established.Firstly,from the overall point of view,combined with the elastic foundation beam theory and the finite difference method,the mechanical calculation method of double row piles under the landslide thrust is studied,and the mechanical calculation formula of double row piles based on the finite difference method is obtained;Then,from the local point of view,combined with the relevant knowledge of Moore Coulomb strength theory,structural mechanics and soil mechanics,the reasonable arch axis is deduced.On this basis,through the relevant mechanical analysis of the triangle compression area at the foot of different types of soil arch,the trace equation of reasonable arch axis and the calculation equation of ultimate bearing capacity and geometric parameters of two types of soil arch are obtained.According to the calculation formula of soil arching mechanics,the reasonable spacing of anti slide piles and row spacing of front and rear piles based on soil arching effect are analyzed and studied,and the upper bound algebraic formula of reasonable spacing of piles and row spacing is obtained.(2)Numerical simulation analysis of soil arching effect of combined anti slide pileIn the aspect of numerical simulation,the development failure process of soil arching effect of composite anti slide pile and the factors influencing soil arching effect are studied from macro and micro perspectives respectively through reasonable assumptionsFrom the macro point of view,based on FLAC 3D software,the pile-soil model of composite anti slide pile is established.The sliding thrust is simulated by applying the uniform load on the boundary.The appropriate element is used to simulate the pile-soil,and the relevant material parameters are defined.The development failure stages of soil arch are simulated,and the factors affecting the development process of soil arch are simulated and analyzed by the control variable method.Combined with the relevant mechanical analysis,the existence of soil arching effect of combined double row piles is verified,and the qualitative conclusion of the influence of pile spacing and soil parameters on the development of soil arching effect of double row piles is obtained under the continuous action of landslide thrust;From the micro point of view,based on PFC discrete element software,the formation and development process of multi-layer soil arching effect of double row piles are analyzed,and the influence of soil micro parameters on the development process of soil arching is simulated and analyzed.The qualitative conclusion of the influence of micro soil particle parameters on the development process of soil arching is obtained;(3)Model test on soil arching effect of double row piles.Based on the test of soil arching effect of double row piles and the data of soil sensors at corresponding positions,the paper studies and analyzes the existence and development of soil arching effect of combined anti slide piles,the transfer and distribution of soil pressure in the relevant process and the retaining effect of anti slide piles,The mode of stress transfer in the process of stress redistribution and the bearing position of the front and back row piles in the retaining structure are obtained.The qualitative conclusion of the influence of landslide thrust load,soil depth and other factors on the development process of soil arch and the retaining effect of the corresponding double row piles is obtained.