戚翼　王平

摘要：本文以哈尔滨地铁二号线南直路车站暗挖段SK25+490断面为背景，通过收集现场监测数据，绘制地表沉降和拱顶下沉的历时变化曲线。运用FLAC3D软件，结合隧道的工程概况建立三维模型，对隧道开挖后地表和拱顶位移的变化趋势进行数值分析。通过综合比对数值分析结果和现场监测数据，发现随着掌子面的推进，隧道围岩的变形可分为快速变形，缓慢增长，基本稳定三个阶段，并且隧道开挖面距离观测点一倍洞径范围内时沉降速率较大，大于两倍洞径后沉降速率开始减缓。通过对比现场监测数据和数值分析的结果发现二者相似度较高，对合理选择施工方法和支护衬砌的类型具有指导意义。

关键词：浅埋隧道;围岩变形;监控量测;数值模拟

中图分类号：U456.31文献标识码：A文章编号：1006-8023（2019）02-0107-05

Analysis of Deformation Characteristics of Surrounding Rockin Shallow Excavation Tunnel

QI Yi， WANG Ping

（School of Civil Engineering， Northeast Forestry University， Harbin 150040）

Abstract：Based on the background of SK25 + 490 section in the underground excavation section of Nanzhi Road Station of Harbin Metro Line 2， the duration curve of surface subsidence and the vault sink are drawn by collecting on-site monitoring data. By using FLAC3D software and combining with the general situation of tunnel engineering， a three-dimensional model is established to numerically analyze the variation trend of ground surface and vault displacement after tunnel excavation. Through comprehensive comparison of numerical analysis results and field monitoring data， it is found that the deformation of tunnel surrounding rock can be divided into three stages： rapid deformation， slow growth and basic stability with the advance of palm face. And the settlement rate of the tunnel excavation face is larger than that of the observation point， and the settlement rate starts to slow down after the double hole diameter. By comparing the results of on-site monitoring data and numerical analysis， it is found that the similarity between the two is relatively high， which has guiding significance for the reasonable selection of construction methods and types of supporting lining.

Keywords：Shallow tunnel; surrounding rock deformation; monitoring measurement; numerical simulation

0引言

隨着地铁在我国各大城市的兴建，浅埋暗挖法以地层改良、时空效应和快速施工等特点在软弱地层中得到广泛应用。本文中隧道暗挖段采用PBA工法施工，PBA工法是浅埋暗挖法的一种，其主要思想是将盖挖及分步暗挖法相互结合起来，发挥各自的优势，当地质条件差、断面特大时，通过边桩、柱、顶底梁和顶拱共同构成初期受力体系，承受施工过程中的荷载，最终形成由初期支护加二次衬砌组合形成的永久承载体系 [1]。

但是在隧道施工过程中引起的地表沉降和围岩的变形问题仍然是设计、施工人员和科研工作者普遍关注的问题 [2]。隧道围……