模型试验模拟不同工况下基坑开挖对既有隧道的影响

为探讨基坑开挖过程对既有隧道内力及变形的影响,通过室内模型试验模拟三种工况下基坑的开挖对既有隧道截面弯矩、土压力、直径变化规律,同时对比分析了各工况下隧道的内力与变形特点。研究结果表明:基坑开挖引起既有隧道截面纵向弯矩变小,横向弯矩变大,导致既有隧道的横向直径拉长,纵向直径压短;基坑开挖过程中,既有隧道横向土压力减小,导致横向内径增大,纵向土压力有所增大,导致隧道截面纵向内径减小;基坑开挖过程中,隧道的深度越大,开挖影响隧道结构的弯矩与位移越小;隧道与基坑的水平间距越小,基坑开挖影响隧道的弯矩与位移变化越大。

Influence of Foundation Pit Excavation under Different Conditions Simulating by Model Test on Existing Tunnel

To explore the influence on internal force and deformation of existing tunnel in excavation of foundation pit, indoor model tests were carried out to simulate the change law of section moment, earth pressure and diameter of existing tunnel in three cases, and at the same time, the features of internal force and deformation of the tunnel in each case were compared. The results show that excavation of foundation pit may cause the section moment of existing tunnel decreased longitudinally and increased horizontally, and then the diameter lengthened horizontally and shortened longitudinally; during the excavation, the existing tunnel is subject to earth pressure decreased horizontally, which leads to increased transverse inner diameter, and increased longitudinally, which leads to decreased vertical inner diameter; and with the increment of tunnel depth, the influence of excavation on the tunnel structure’s bending moment and displacement reduces gradually; the smaller the horizontal distance between the tunnel and the foundation pit, the greater the influence of excavation on the tunnel moment and displacement is.