库水作用下含挡墙滑坡的抗滑桩加固空间位置优化研究

Spatial Position Optimization of Anti-slide Pile Reinforcement of Landslide including Retaining Wall under the Action of Reservoir Water

库水变动条件下,以滑坡体、挡墙和抗滑桩为优化系统,利用有限差分法对抗滑桩的空间位置进行优化。通过数值模拟计算滑体和支护结构不同点的位移,根据位移曲线将其划分为三个阶段,即稳定阶段、加速变形阶段和破坏阶段。稳定阶段表明了抗滑桩支护作用的有效性,加速变形阶段和破坏阶段表明了抗滑桩防治效果逐渐失去有效性,因此需要将抗滑桩布置在滑体的前部。除了发挥抗滑桩的抗滑作用还能够使挡墙起到一定的支护作用,保证了滑体的稳定性。基于此,利用强度折减法求取不同桩墙间距下的含挡墙和抗滑桩结构的滑坡安全系数,研究发现在间距较小时滑坡安全系数较大,间距较大时安全系数减小且保持在一定的范围内;这既表明了抗滑桩布置在滑体前部的合理性,又保证桩墙间距为20 m时滑体稳定性最高。因此,将抗滑桩布置在桩墙间距20 m附近是最优的,这也适用于孕育期剧动牵引式人工水库泄水渗透压力型滑坡,为该类滑坡的防治提供理论依据。

Water level changes in reservoir was considered,the sliding mass,retaining wall and anti-slide piles were used as an optimization system,and then the finite difference method was used to optimize the spatial position of the anti-slide piles. Numerical simulation is used to work out displacement of different points in sliding mass and supporting structure,according to the displacement curves,it can be divided into three phases,namely the stable phase,deformation accelerating phase and failure phase. The stable phase indicates the efficiency of the supporting anti-slide piles,while the deformation accelerating phase and failure phase shows that the anti-slide piles are gradually losing its efficiency. Therefore the anti-slide piles should be located in the front of the sliding mass,in this way,not only the piles could exert themselves on resisting sliding,but the retaining wall would play a role in supporting,thus ensure the stability of the sliding mass. Based on this,strength reduction method was used to calculate different safety factors of landslides with different distance of anti-slide piles and retaining wall. The study found that the safety factor is higher when that distance is shorter,it decreases when that distance gets longer and it is kept in a certain range. It not only shows the rationality of locating the anti-slide piles in the front of the sliding mass,but ensures the highest stability when the distance between anti-slide piles and retaining wall is 20 m. Therefore,setting the distance between the anti-slide piles and the retaining wall around of 20 m is optimal,this could also be applied to dynamic traction landslides which are in incubation period and are induced by osmotic pressure from artificial reservoir discharging,thus provide a theoretical basis for prevention and treatment of those landslides.