过江隧道深基坑中SMW工法加钢支撑围护结构现场监测分析

第29卷第6期岩石力学与工程学报V ol.29 No.6 2010年6月Chinese Journal of Rock Mechanics and Engineering June，2010

过江隧道深基坑中SMW工法加钢支撑

围护结构现场监测分析

张忠苗1，2，赵玉勃1，2，吴世明3，王博3

(1. 浙江大学软弱土与环境土工教育部重点实验室，浙江杭州 310058；2. 浙江大学岩土工程研究所，浙江杭州 310058；

3. 杭州庆春路过江隧道有限公司，浙江杭州 310007)

摘要：杭州庆春路过江隧道是“钱江第一隧”，其江北岸基坑是典型的粉性土基坑，最大开挖深度16 m，主要采用SMW工法(劲性水泥土搅拌连续墙)加钢支撑的围护结构体系，围护桩最长达27 m。基坑开挖过程监测数据表明：围护桩的最大水平位移与开挖深度及时间密切相关，支撑的架设及内部结构能很好限制桩体变形；气温、降雨等外界条件的变化对支撑轴力的影响较大，临近基坑支撑的拆除也会产生重大影响；钢支撑轴力均未达到设计值，应对设计方案进行优化；基坑降水及由此引发的渗流会改变土体有效应力，是基坑周围地表沉降的主要原因，同时相邻基坑的施工也会产生一定影响；地下水位的变化能很好反应围护桩的止水效果，可作为判断基坑是否出现漏水的指标。对于粉性土基坑，有效控制基坑周围水的变化，对保持基坑安全有重要意义。

关键词：隧道工程；过江隧道；深基坑；SMW工法；水平位移；支撑轴力；地表沉降；地下水位

中图分类号：U 45 文献标识码：A 文章编号：1000–6915(2010)06–1270–09

IN-SITU MONITORING ANALYSIS OF RETAINING STRUCTURES OF SMW PILES PLUS STEEL SUPPORT IN DEEP FOUNDATION PIT OF A

RIVER-CROSSING TUNNEL

ZHANG Zhongmiao1，2，ZHAO Yubo1，2，WU Shiming3，WANG Bo3

(1. MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering，Zhejiang University，Hangzhou，Zhejiang310058，

China；2. Institute of Geotechnical Engineering，Zhejiang University，Hangzhou，Zhejiang310058，China；3. Hangzhou Qingchun Road River-crossing Tunnel Co.，Ltd.，Hangzhou，Zhejiang310007，China)

Abstract：The pit at the north side of the Hangzhou Qingchun Road river-crossing tunnel，which is the first one that crossed beneath the famous Qiantang River，is typical silt-based pit，with the maximum excavation depth of 16 m. In this project，retaining structures of steel supports with SMW(soil mixing wall) method are mainly applied，of which the longest piles are up to 27 m. According to the analysis of on-site monitoring data，it could be obtained that：(1) the maximum horizontal displacement of piles is closely related to the excavation depth and time，and the set up of piles and the internal structures played a good role in restraining the piles' displacement；and (2) changes of external conditions such as temperature，rainfall，etc. also have considerable influence on axial force. In addition，the removal of steel support of adjacent pit would also impact axial force significantly. The measured values of steel support axial force are much smaller than the design values，so it is necessary to optimize the preliminary design. The changes in effective stresses resulted from dewatering and seepage are the main factors inducing settlement of ground surface，and at the same time，the construction of adjacent pit has a certain impact on surface subsidence. The variation of groundwater levels could reflect the watertight effect of the retaining

收稿日期：2010–01–08；修回日期：2010–03–07

作者简介：张忠苗(1961–)，男，1999年于浙江大学获岩土工程专业博士学位，现任教授、博士生导师，主要从事基础工程和桩基础及其检测方面的