Field monitoring and analysis of soil deformation of curved steel pipe jacking in Gongbei tunnel

To ascertain the soil deformation law in the construction of curved pipe jacking, ground deformation, layered settlement and lateral deformation of deep soil have been analyzed by field monitoring of soil deformation data in different types of soil in the curved pipe jacking roof of Gongbei tunnel. The results show that the curved pipe jacking induced ground settlement groove curve shows asymmetry. The variation law of ground settlement and deep soil deformation in different soil is consistent, and the mud pressure, excavation face support force and friction resistance have great influence on the deep soil deformation, but the maximum deformation is related to the soil type. Adjacent curved pipe jacking construction will cause the accumulative deformation of surrounding soil, due to the supporting effect of the completed pipe jacking on surrounding soil, the accumulated value of this part of soil is small. The maximum settlement values of single curved pipe jacking are artificially fill > sand layer > mucky soil. during construction of adjacent jacking pipes, the cumulative deformation values are as follows: mucky soil > artificial fill > sand layer, indicating that the deformation of mucky soil is more significant under multiple disturbances. The soil loss caused by relative position of curved pipe jacking and tunnel is the main reason for the ground settlement deviation. The calculated result of modified Peck formula is accordance with measured values, which can be used to predicate the surface deformation caused by curved pipe jacking.