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针对西安地铁上覆含有古土壤的黄土地层中盾构施工引起的地表沉降,在分析其产生机理、盾构施工数值模拟过程、基于经验公式的Peck地表沉降计算方法的基础上,探讨了基于注浆效果、支护压力以及偏心超挖的等代层厚度计算方法;具体分析了盾构施工数值模拟过程中的等代层弹性模量和掌子面支护压力比与Peck地表沉降计算公式中最大沉降量和沉降槽宽度之间的关系。研究结果表明,在含有古土壤的黄土地层中进行盾构施工数值模拟时,等代层模量的取值在5～10MPa范围之内,当等代层模量小于5 MPa时,隧道围岩将产生较大的塑性变形;掌子面支护压力比取值在0.5～1.0范围之内,当掌子面支护压力比小于0.5时,掌子面附近土体将产生较大的塑性变形,当掌子面支护压力比大于1时,地表将产生隆起变形。
In view of the ground subsidence caused by shield construction in the loess stratum with ancient soil overlying Xi’an metro, based on the analysis of its production mechanism, the numerical simulation of shield construction and the calculation method of Peck surface settlement based on empirical formula, Slurry effect, supporting pressure and eccentric overburden thickness calculation method; concrete shield tunneling numerical simulation process and the generation of subgrade elastic modulus and support surface pressure ratio and Peck surface settlement formula Relationship between maximum settlement and settlement tank width. The results show that in the numerical simulation of shield construction in the loess stratum with ancient soil, the equivalent layer modulus is in the range of 5-10 MPa. When the equivalent layer modulus is less than 5 MPa, the tunnel surrounding rock Will have a greater plastic deformation; face support surface pressure ratio value in the range of 0.5 to 1.0, when the support surface pressure ratio is less than 0.5, the soil near the face will have a larger plastic deformation , When the noodles support pressure ratio greater than 1, the surface will have a bulge deformation.