管棚注浆支护隧道开挖引起地表变形特征分析

隧道开挖引起的地表变形是工程安全的重要指标,基于管棚注浆隧道开挖引起的地层受力分析,将地表变形影响因素分为注浆压力、附加荷载和地层损失,并引入Mindlin解和Peck公式,获得了隧道引起的地表变形计算公式。通过对地表变形特征进行分析,结果表明:岩土力学参数对地表变形最大值有显著影响,但对沉降影响宽度影响甚微;沉降槽宽度、地层损失率和沉降宽度与沉降槽宽度比值(I/i)均随内摩擦角和黏聚力增大而减小,弹性模量对沉降槽宽度几乎没有影响,随弹性模量增大,沉降槽宽度稳定在7.6~7.9,地层损失率迅速减小并在1.2‰左右趋于稳定,I/i则迅速增大并稳定在3.0左右。隧道参数对沉降最大值和沉降影响宽度均有显著影响,且影响幅度没有减缓的趋势;在单一地层中,随着埋深增加,沉降槽宽度、地层损失率均呈直线增大,I/i值先增大后减小;随洞径增大,沉降槽宽度呈线性增大,地层损失率呈线性减小,I/i值先增大后减小,最大值为3.1左右。

The Characteristic Analysis of Ground Deformation due to Tunnel Excavation Used Pipe Roof Grouting Support System

Ground deformation caused by tunnel excavation is an important index of engineering safety. Based on the stress analysis caused by the excavation of tunnel under the grouting with pipe-roof, the main influence factors of ground deformation are divided into grouting pressure, additional load and ground loss. And the formula of calculating the ground deformation has been presented by introducing the Mindlin solution and Peck formula. The characteristic of ground deformation has been studied, and the research results reveal that mechanics parameters of rock and soil mass have significant effect on the maximum ground settlement but little effect on the width of settlement (I). The width of settlement trough (i), ground loss rate (η) and I/i decrease with the increase of friction angle and cohesion. The value of i is 7.6~7.9 and is not affected by the elastic modulus. With the increase of elastic modulus, the value of η decreases rapidly and stabilizes around 1.2‰, but the value of I/i increases rapidly and stabilizes around 3.0. Different from the mechanics parameters of rock and soil mass, the tunnel parameters have significant effect on the maximum ground settlement and the width of settlement (I), and the influence amplitude does not decrease. With the increase of tunnel depth in the single layered foundation, the value of i and η is increase as a linear, but the value of I/i is increases at first then decreases. With the increase of tunnel diameter, the value of i increases as a linear and the value of η decreases as a linear, but the value of I/i increases at first then decreases and its maximum value is around 3.1.