软黏土地层基坑开挖对旁侧隧道影响离心模型试验研究

doi:10.11779/CJGE202006018

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摘要为研究软黏土地层基坑开挖对旁侧隧道的影响,开展了相似比为1∶120的离心模型试验。试验获得了基坑开挖引起的地层不排水抗剪强度、土体孔隙水压力、隧道周围地层水平向土压力、地表沉降、隧道沉降和弯矩响应规律。试验结果表明：①基坑底暴露导致坑底和隧道周围土体超孔压长时间演变,并伴随着隧道周围地层水平向土压力大小和分布形式的持续变化;②基于竖向有效应力衰减程度的土体扰动度评价方法,发现位于坑底下方0.3倍和0.7倍开挖深度处的土体扰动度分别达到了0.33,0.21;③因既有隧道的约束作用,围护墙外侧地表沉降主要位于Peck（1969年）预测的地表沉降Ⅱ区;④基坑开挖完成后,地表沉降、隧道沉降和弯矩持续发展,开挖完成815 d后隧道总沉降达到了开挖期间沉降的1.6倍。固结和蠕变变形是开挖卸载后隧道变形和内力持续发展的主要原因,实际工程中应尽量减少坑底暴露时间。

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	陈仁朋
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关键词 ：离心模型试验, 基坑, 隧道, 软黏土, 沉降

Abstract：The centrifuge modeling with a similarity ratio of 1∶120 is carried out to investigate the impacts of an excavation on a nearby tunnel in soft clayey strata. The responses of undrained shear strength, pore water pressures, horizontal earth pressures around the tunnel, ground settlements, tunnel settlements and bending moments are obtained. The test results show that: (1) The exposure of the excavation base leads to the continuous evolution of the excess pore water pressures of soils below the excavation base and around the tunnel, together with both the magnitude and distribution changes of horizontal earth pressures around the tunnel. (2) Using the effective vertical stress reduction ratio-based equation for soil disturbance degree (SDD), SDD of soils with vertical distances of 0.3 and 0.7 times the excavation depth below the excavation base are 0.33 and 0.21, respectively. (3) Due to the existing tunnel, the ground surface settlements behind the diaphragm wall mainly locate at Zone II predicted by Peck (1969). (4) After excavation, the ground surface settlements, tunnel settlements and bending moments develop continuously. The tunnel settlement at 815 days after excavation is 1.6 times that during excavation stage. The consolidation and creep may be the main reasons for the continuous development of tunnel deformations and internal forces after excavation, implying that the exposure time of the excavation base should be minimized in real projects.

Key words： centrifuge modeling excavation tunnel soft clay settlement

收稿日期: 2019-09-23

ZTFLH:

TU43

基金资助:国家自然科学基金重点项目(51938005);宁波轨道交通集团有限公司科研项目(K18-512103-022)

通讯作者: E-mail: fymeng@hnu.edu.cn

作者简介: 陈仁朋(1972— ),男,博士,教授,主要从事城市地下空间和交通岩土工程方面的研究。E-mail: chenrp@hnu.edu.cn。

引用本文:

陈仁朋, 刘书伦, 孟凡衍, 叶俊能, 朱斌. 软黏土地层基坑开挖对旁侧隧道影响离心模型试验研究[J]. 岩土工程学报, 2020, 42(6): 1132-1138. CHEN Ren-peng, LIU Shu-lun, MENG Fan-yan, YE Jun-neng, ZHU Bin. Centrifuge modeling of excavation effects on a nearby tunnel in soft clay. Chinese J. Geot. Eng., 2020, 42(6): 1132-1138.

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http://manu31.magtech.com.cn/Jwk_ytgcxb/CN/10.11779/CJGE202006018 或 http://manu31.magtech.com.cn/Jwk_ytgcxb/CN/Y2020/V42/I6/1132

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