砂土地层暗挖施工结合MJS工法应用研究  

Application Research on Underground Excavation Construction Combined with MJS Method in Sand Stratum

作　　者：弓毅伟 陈杰华 唐欣薇[2] GONG Yiwei;CHEN Jiehua;TANG Xinwei(China Tunnel Construction Group Co.,Ltd.,Guangzhou,Guangdong510228,China;School of Civil Engineering and Transportation,South China University of Technology,Guangzhou,Guangdong510640,China)

机构地区：[1]广东华隧建设集团股份有限公司,广东广州510228 [2]华南理工大学土木与交通学院,广东广州510640

出　　处：《施工技术(中英文)》2024年第23期36-41,46,共7页Construction Technology

摘　　要：受限于砂土地层较差的稳定性,传统暗挖法较少应用于砂土地层。在原有大管棚+小导管支护的基础上,施作MJS桩体对暗挖通道周遭原状土进行加固止水改良,结合广州地铁8号线北延段上步站Ⅰ号出入口暗挖隧道工程,探究MJS水平桩精度控制、管棚顶进精度控制、管棚沉降控制等风险因素,并提出相应对策。最后通过分析暗挖隧道下部电力隧道的收敛与沉降监测数据,评价MJS预加固结合管棚导管支护的控制效果。实践结果表明:MJS成孔过程中,每进尺3m采用水平精度测量仪进行测量,可有效提高该工法在砂土地层中的成孔精度。将管棚顶进过程分为4个阶段,并依次确保入孔定位准确、跟踪顶进过程、修正偏差、完成终孔分析,可有效纠偏。此外,破碎排渣与钢管顶进同时进行可有效减小管棚施工造成的扰动。MJS预加固+管棚导管支护的组合工法能有效将暗挖施工对周边重要建筑物的影响控制在设定的限值内。Due to the poor stability of the sand stratum,the traditional underground excavation method is rarely applied to the sand stratum.Based on the original support system consisting of pipe-roof and small pipes,the MJS pile was applied to strengthen the undisturbed soil around the underground excavated channel to improve the water sealing.Combined with the underground excavated tunnel project at Shangbu Station in the north extension of Guangzhou Subway Line 8,this paper explores the risk factors such as precision control of MJS horizontal pile,pipe-roof jacking precision control and pipe-roof settlement control in the construction process of this project from the perspective of risk control,and puts forward the corresponding countermeasures.Finally,the convergence and settlement monitoring data of the electric power tunnel under the underground tunnel were analyzed to evaluate the control effect of MJS pre-reinforcement combined with pipe-roof support.Practice shows that in the process of MJS hole formation,the horizontal precision measuring instrument is used to measure the hole formation in the sand stratum,which can effectively improve the hole formation accuracy of the method.The jacking process of pipe shed is divided into four stages,and the correct hole positioning is ensured,the jacking process is tracked,the deviation is corrected,and the final hole analysis is completed,which can effectively solve the correction problem.In addition,the disturbance caused by pipe-roof construction can be effectively reduced by adopting the construction method of crushing and discharging slag and pipe jacking simultaneously.The combined construction method of MJS pre-reinforcement and the support system consisting of pipe-roof and small pipes can effectively control the influence of excavation construction on the surrounding important buildings within the limit value set by this project.

关 键 词：隧道 砂土地层 暗挖 MJS水平桩 沉降 支护 监测 

分 类 号：TU753[建筑科学—建筑技术科学]