隧道-基坑多重开挖对既有桩影响的参数分析

隧道和基坑作为两种不同的开挖形式,是目前常见的城市地下工程。随着城市地下空间利用率的提高,既有桩周围存在隧道和基坑依次开挖的工况越来越普遍。从隧道-桩-基坑三者相对位置的角度出发,以“先隧道后基坑”开挖顺序为例,采用ABAQUS建立数值模型开展参数分析,并与相关试验结果进行对比,结果表明:Z₀/L_p对既有桩基附加沉降、水平位移和弯矩均呈现先增后减的变化规律,桩身轴力在Z₀/L_p不同时表现的响应模式不同。H/D或d/H_e越大,桩基附加沉降越小并趋于稳定;最大桩身水平位移的位置随H/D的增大由桩端逐渐上移至桩身中部,但基本不受d/H_e的影响;桩身弯矩随着水平间距的增大先递减后递增并趋于稳定。研究结果可为实际工程设计和施工提供参考。

Parameter Analysis on the Influence of Multiple Excavation of Tunnel-pit on Existing Piles

Tunnels and foundation pits, as two different forms of excavation, are currently co mmon urban underground projects. With the improvement of urban underground space utilization, there are tunnels and foundation pits around the existing piles. Digging conditions are becoming more co mmon. From the perspective of the relative positions of the tunnel, pile, and foundation pit, taking the excavation sequence of "tunnel first and then foundation pit" as an example, ABAQUS is used to establish a numerical model for parameter analysis and it is compared with relevant test results. The results show that: the influences of Z₀/L_p on the additional settlement, horizontal displacement and bending moment of the existing pile foundation increase first and then decrease. The response pattern of the pile axial force is different when Z₀/L_p is different. The larger the H/D or d/H_e, the smaller the additional settlement of the pile foundation and tend to be stable; the position of the maximum horizontal displacement of the pile body gradually moves from the pile end to the middle of the pile body with the increase of H/D, but it is not affected by d/H_e; the bending moment of the pile body decreases with the increases of the horizontal distance, then increases and stabilizes. The research results can provide references for actual engineering design and construction.