摘要
土压平衡盾构穿越富水复合地层时,常面临螺旋出土器喷涌和刀盘结泥饼风险。以南昌地铁4号线盾构隧道穿越的富水砾砂和泥质粉砂岩复合地层为研究对象,进行室内渣土改良试验,研究动态变化的复合地层中采用泡沫剂和膨润土泥浆联合改良的渣土改良方案及改良剂合理添加比。分析改良剂参数与土体力学参数间的相关性,得到改良剂参数对盾构推力和扭矩的影响规律。现场应用结果验证提出改良方案的有效性。研究结果表明,(1)砾砂渣土坍落度随改良剂添加比的增大而增大,渗透系数随改良剂添加比的增大而减小,当添加比>6%时,渣土渗透性已小于喷涌发生条件,改良剂合理添加比为6%~8%;(2)中风化泥质粉砂岩渣土的合理含水率区间为17.8%~21.1%,采用泡沫和膨润土泥浆进行联合改良可有效改善渣土流塑性和抗渗性,改良剂合理添加比为16.6%~21.4%;(3)渣土内摩擦角、抗剪强度均随泡沫剂和膨润土泥浆浓度增大而减小,盾构推力和扭矩受泡沫剂溶液和膨润土泥浆浓度的影响显著,均随改良剂浓度的增大而减小;(4)泡沫剂和膨润土泥浆用量均随中风化泥质粉砂岩地层占比增加而逐渐增大,改良参数优化后改良剂用量、盾构推力、扭矩等均明显下降,改良剂用量平均降幅为25.8%,盾构推力和扭矩平均降幅均超过15%,且盾构推力和扭矩波动较为稳定。
When crossing water-rich composite strata,earth pressure balance shields often face the risks of water gushing from the screw conveyor and cutterhead clogging.Taking the composite strata of water-rich gravelly sand and moderately weathered argillaceous siltstone traversed by a shield tunnel on Nanchang Metro Line 4 as the research object,laboratory tests on soil conditioning were conducted to investigate a soil conditioning scheme using a combination of foaming agent and bentonite slurry in dynamically changing composite strata,as well as the reasonable injection ratios of the conditioners.The correlation between conditioner parameters and soil mechanical parameters was analyzed,and the influence patterns of the conditioner parameters on shield thrust and torque were obtained.The effectiveness of the proposed soil conditioning scheme was verified through on-site application results.The results showed that:(1)the slump of conditioned gravelly sand increased with an increase in the conditioner injection ratio,while the permeability coefficient decreased.When the injection ratio exceeded 6%,the permeability of the conditioned soil was lower than the threshold for water gushing from the screw conveyor.Therefore,the reasonable injection ratio for the conditioners was determined to be 6%~8%.(2)The reasonable water content range for the conditioned moderately weathered argillaceous siltstone was 17.8%to 21.1%.The combined conditioning of foaming agent and bentonite slurry could effectively improve the flow plasticity and impermeability of the conditioned soil,and the reasonable injection ratio of the conditioners was 16.6% to 21.4%.(3)The internal friction angle and shear strength of the conditioned soil decreased with increasing concentration of the foaming agent and bentonite slurry.Shield thrust and torque were significantly affected by the concentration of the foaming agent and bentonite slurry,and both decreased with an increase in the conditioner concentration.(4)The volume foaming agent and bentonite slurry increased gradually with the increasing proportion of moderately weathered argillaceous siltstone in the strata.After the optimization of soil conditioning parameters,conditioner volume,shield thrust,and torque decreased significantly.The average reduction in conditioner volume was 25.8%,and the average reductions in shield thrust and torque both exceeded 15%.Furthermore,the fluctuations in shield thrust and torque were relatively stable.
作者
许勇
李哲宇
张炜
夏明
张康健
张志强
XU Yong;LI Zheyu;ZHANG Wei;XIA Ming;ZHANG Kangjian;ZHANG Zhiqiang(Shanghai Tunnel Engineering and Rail Transit Design and Research Institute,Shanghai 200235,China;Nanchang Metro,Nanchang 330038,China;School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China)
出处
《铁道标准设计》
北大核心
2025年第12期170-180,共11页
Railway Standard Design
基金
国家自然科学基金高铁联合基金项目(U1934213)
南昌轨道交通集团有限公司科研项目(2019HGKYB003)。
关键词
地铁
土压平衡盾构
掘进参数
富水复合地层
渣土改良
metro
earth pressure balance shield
tunneling parameters
water-rich composite strata
soil conditioning
