地震作用下微型桩复合土钉墙动力响应分析

Dynamic response analysis of micro-pile composite soil nailing retaining wall under earthquakes

微型桩复合土钉墙支护结构在地震作用下能充分发挥增强土体自稳能力、提高基坑支护结构整体稳定性的优势,研究其结构动力响应,可为地震作用下基坑支护设计提供参考依据。文章利用有限差分软件,建立某微型桩复合土钉墙支护基坑的三维有限差分模型,对比分析了有无微型桩对复合土钉墙支护结构位移场及塑性区发展的影响,研究了地震作用下微型桩排数、长度和桩径对基坑边坡位移、支护结构内力的影响。结果表明:在地震作用下,在基坑边坡支护中设置微型桩能够有效控制基坑的水平位移和坑后沉降、减小支护结构的内力,但是增加微型桩排数对基坑边坡的变形和支护结构内力影响较小;增加微型桩桩长,可以减小基坑边坡的变形和支护结构内力,但其作用会随微型桩长度的增加而减弱;增加微型桩桩径仅对基坑边坡的水平位移有明显减小作用。

The micro-pile composite soil nailing wall can fully enhance the soil self-stability and improve the overall stability of excavation retaining structure under the earthquakes.The study on the dynamic response of the retaining structures can provide a reference for the design of the excavation retaining structure.In this paper,a three-dimensional finite difference model was established using finite difference program to simulate a excavation supported by a micro-pile composite soil nailing wall.The influence of the micro-piles on the displacement field and plastic zone development of the composite soil nailing wall support structure was analyzed.Meanwhile,the influence of primary factors,including the number,length and diameter of the micro-pile rows on excavation displacement and the internal force of the retaining structure under the action of the earthquake was studied.It also studies the influence of the number,length and diameter of the micro-pile rows on the slope displacement of the foundation pit and the internal force of the retaining structure under the action of the earthquake.The results show that under the action of an earthquake,the installation of micro-pile in the slope support of the foundation pit can effectively control the horizontal displacement of the foundation pit and the settlement behind the pit and reduce the internal force of the retaining structure.However,increasing the number of rows of micro-piles only reduces their bending moment,which has less effect on the deformation of the foundation pit slope and the internal force of the retaining structure.Increasing the length of the micro-pile can reduce the deformation of the foundation pit slope and the internal force of the retaining structure,but the effect decreases with the increase of the length of the micro-pile.The increase of the micro-pile diameter will significantly reduce the horizontal displacement of the slope of the foundation pit.