双向地震作用下的双排桩边坡参数敏感性分析

摘要

以门式双排抗滑桩为例,采用有限元软件Ansys建立仿真模型,通过改变模型中桩长、桩排距、桩间距,以及土的抗剪强度参数,对门式双排桩边坡在双向地震波作用下的受力性状进行了研究,结果表明,在动力作用下,当桩的锚固长度小于等于H/2时,静动峰值弯矩,桩身最大剪力和桩侧最大土压力会随抗滑桩锚固深度增加而增加,而当锚固长度大于H/2时,这3种力学效应均增长减缓,之后开始缓慢减小;当门式双排桩的桩排距在5.5 m时,静动峰值弯矩与桩侧土压力最大,其后随着桩排距增大逐渐减小;当双排桩间距为4倍桩截面宽度时,桩间的土拱效应最为显著;滑体土及滑带粘聚力c(25 kPa)和内摩擦角φ(24.1°)逐渐增大时,边坡稳定性提高;当达到1.2倍时, 静动峰值弯矩、桩身最大剪力,及桩侧最大土压力降低幅度最大,其后趋于平缓.%The simulation model of slope with portal frame anti-slide piles is established with the finite element software Ansys in this paper.The force conditions under bilateral earthquake actions are studied through changing the model's parameters such as depth of pile underground, pile row distance, pile space and shear strength parameters of soil.The results show that the static and dynamic peak bending moment, maximum shear stress of pile and maximum soil pressure on pile sides will increase with the increasing of anti-slide pile's anchorage depth when the anti-slide pile's anchorage depth is less than or equal to H/2, and these three mechanical effects will all increase slowly and then gradually decrease when the anti-slide pile's anchorage depth is more than H/2 under dynamic action.Besides, the static and dynamic peak bending moment and soil pressure on pile sides will reach the maximum when the row distance of portal frame anti-slide piles is 5.5m, and later these two mechanical effects will decrease with the increasing of the pile row distance.The soil arching effect between piles will be most significant when the pile space is four times the width of pile section.Also slope stability will increase when the cohesion c(25 kPa) and internal friction angle φ(24.1°) of soil slide body and slide zone gradually go up, and the decrease extent of static and dynamic peak bending moment, maximum shear stress of pile and maximum soil pressure on pile reaches the maximum when the values of c and φ are up to 1.2 times, and then it tends to be gentle.