上软下硬地层浅覆土超大直径盾构扰动规律研究  

Disturbance Law Induced by Super Large Diameter Shield Under Shallow Overlying Soil in Upper-soft and Lower-hard Stratum

作　　者：刘厚朴 LIU Houpu(China Railway Southern Investment Group Co.,Ltd.,Shenzhen,Guangdong 518000,China)

机构地区：[1]中铁南方投资集团有限公司,广州深圳518000

出　　处：《施工技术（中英文）》2023年第7期128-135,共8页Construction Technology

基　　金：中铁南方2021年度科技创新计划(ZTNF-2021-5)。

摘　　要：为揭示上软下硬地层中浅覆土盾构施工引起的扰动规律,以深圳市妈湾超大直径海底隧道始发段为依托,建立了浅覆土段双线盾构三维数值模型,根据地表沉降数据验证模型并分析了浅覆土双线盾构的地表沉降规律。基于莫尔-库伦强度理论提出强度余量的概念,重点分析了不同掌子面支护力、注浆压力下双线盾构显著扰动范围交叠区内土体单元的强度余量变化历程。结果表明:浅覆土段双线盾构分别诱发的地表沉降交叠范围较小,地表呈现“ω”形沉降;随着后开挖线盾构掌子面支护力的提高,双线间土体单元在盾构到达前至盾构穿越过程中的强度余量下降更大,更接近塑性;随着后开挖线盾构注浆压力的下降,双线间土体单元在盾尾脱出3环内的强度余量下降更大,更接近塑性;计算结果表明,当后开挖线盾构掌子面支护力相比土压提高50kPa时或盾构注浆压力低至160kPa时,双线间土体单元已接近塑性。To reveal the disturbance law induced by the super-large diameter shield under shallow overlying soil in the upper-soft and lower-hard strata,this paper establishes a three-dimensional numerical simulation model of the double-line shield based on starting section of submarine tunnel in Shenzhen Mawan.According to the monitored data,the model is verified,and the law of surface settlement is analyzed.Based on the Mohr-Coulomb strength theory,the concept of strength margin is proposed.The evolution of the strength margin of the soil element between the double lines under different face support pressures and grouting pressures is discussed.Based on the results,the overlapping range of the surface subsidence induced by the double-line shield in the shallow overlying soil section is relatively small,leading a“ω”settlement trough.If the face support pressure increases,the strength margin of the soil element decreases more before the shield arrives and during the shield crossing.With the decrease of the shield grouting pressure,the strength margin of the soil element decreases more during three rings after shield tail.When face support pressure is 50kPa higher than the earth pressure or the grouting pressure is as low as 160kPa,the element is close to plasticity.

关 键 词：隧道 盾构 上软下硬地层 浅覆土 数值模拟 沉降 

分 类 号：TU455.4[建筑科学—岩土工程]