摘要
[目的]复杂地质和超深开挖条件下,地下连续墙成槽施工过程中槽壁的稳定性是目前工程界研究的难点和重点。为掌握宁波地铁7号线宁慈路站东侧WE-15幅76 m超深地下连续墙槽段施工时槽壁塌孔原因,需对该工程进行针对性分析并提出解决方案。[方法]利用PLAXIS 3D有限元软件模拟地下连续墙成槽施工过程,研究软土地层中地下连续墙施工过程中的槽壁稳定性特征及其主要影响因素,与现场超声波检测结果相结合验证模型的准确性。[结果及结论]槽壁水平位移的发展主要集中在成槽前期,即开挖至(4)2b粉质黏土层阶段,其原因是宁波地区第(4)层土层含粉砂性比较重,成槽抓斗反复抓土过程中会扰动泥浆,对槽壁形成卸力和冲击,在泥浆护壁上形成吸附孔隙,外围地下水极易涌入槽内,并带动局部粉砂涌入槽内,容易引发局部塌孔;成槽结束时槽壁水平位移最大值为18.18 mm,位于地面以下25 m处,与实际塌孔位置接近;泥浆重度和加固措施对槽壁稳定性具有显著影响,通过提高泥浆重度和对槽壁进行加固均能有效控制槽壁水平位移。
[Objective]Under complex geological and ultra-deep excavation conditions,maintaining trench wall stability during diaphragm wall construction remains a critical challenge in engineering research.To identify the causes of trench wall collapse during the construction of the 76 m ultra-deep diaphragm wall trench section(WE-15)on the east side of Ningci Road Station of Ningbo Metro Line 7,it is necessary to carry out targeted analysis and propose corresponding solutions.[Method]The PLAXIS 3D finite element software is used to simulate the diaphragm wall trenching process,investigating the stability characteristics of trench walls in soft soil stratum and their key influencing factors.The accuracy of the model is validated by comparing the simulation results with on-site ultrasonic detection data.[Result&Conclusion]The horizontal displacement of the trench wall primarily occurs in the early stage of trenching,specifically when excavating the④2b silty clay layer.The reason is that the fourth soil layer in Ningbo region contains a high silt content,and repeated excavation with a trenching grab disturbs the slurry,leading to uploading and impact effects on the trench wall.This process creates adsorption pores in the slurry wall,allowing groundwater to easily flow into the trench and carry local silt deposits,thereby increasing the risk of localized collapse.At the end of trenching,the maximum horizontal displacement of the trench wall is 18.18 mm,occurring at a depth of 25 m below ground level,closely aligning with the actual collapse location.The stability of the trench wall is significantly influenced by slurry density and reinforcement measures,and both increasing slurry density and reinforcing the trench wall effectively control horizontal displacement.
作者
叶如
王毅
曹昱
雷宇
相龙胜
周俊宏
YE Ru;WANG Yi;CAO Yu;LEI Yu;XIANG Longsheng;ZHOU Junhong(Construction Branch of Ningbo Rail Transit Group Co.,Ltd.,315101,Ningbo,China;Zhejiang Huazhan Research and Design Institute Co.,Ltd.,315012,Ningbo,China;CCCC Tunnel Engineering Co.,Ltd.,100102,Beijing,China;Ningbo Regional Railway Investment and Development Co.,Ltd.,315101,Ningbo,China)
出处
《城市轨道交通研究》
北大核心
2025年第3期118-122,共5页
Urban Mass Transit
关键词
地铁车站
地下连续墙
槽壁塌孔
槽壁水平位移
槽壁加固
underground station
underground diaphragm wall
trench wall collapse
trench wall horizontal displacement
trench wall reinforcement
