Study On The Mechanics Characteristics And Influencing Factors Of Double-row Anti-sliding Piles For Supporting Large Moraine Deposits

The ancient glacial remains in Southwest China are widely distributed.In the construction of hydropower engineering or highway engineering,some problems of the stability of some large moraine deposits are often encountered.Because of the characteristics of thick accumulation,poor sorting and steep interface,the sliding thrust is very large,and the traditional single row anti-sliding piles can not meet the requirement of sliding resistance.The adoption of double-row anti-sliding piles can not only improve the anti slide force,but also solve the problem of difficult layout.But the double-row anti-sliding pile system is very complex,and the factors that affect the force of the front and back piles are not fully understood.In this paper,two methods of theoretical analysis and numerical simulation are used to study the mechanical characteristics and influencing factors of double-row anti-sliding piles for supporting large moraine deposits.The main contents and results are as follows:(1)The engineering geological conditions,typical geological characteristics,deformation and failure modes and stability of a moraine deposit in southwestern China are studied.It is concluded that the deposit is stable in the natural state,but the local instability will occur under the situation of the rainstorm,earthquake and water storage.(2)Based on the deformation compatibility principle of pile and soil,the formulas for calculating the displacement and interaction force of double-row anti-sliding piles and soil are derived.It is concluded that the transfer of sliding thrust in the row of soil is mainly realized by the interaction between pile and soil.By using the method of changing the single parameter,it is concluded that the pile spacing,the section size of the pile and the potential slip surface inclination have important influence on the distribution ratio of the sliding thrust in the front and rear piles.(3)The double row pile supporting structure is simulated by using the solid element and the pile structure unit respectively.The distribution characteristics of soil pressure and the influence of structural parameters on the internal force and displacement of pile groups are studied when the double-row piles are used to reinforce the moraine deposits.After the optimization of the structural parameters of the double row piles,the stability coefficient of the moraine deposits in the study area is greatly improved.(4)Based on the "m" method in the foundation coefficient method,the existing calculation methods are improved and modified,and the internal force calculation method of double-row anti-sliding piles is proposed.The results show that the method is feasible and effective in a certain range.