Affiliation:
1. Zhejiang East China Engineering Construction Management Co., Ltd., Hangzhou 311122, China
2. State Key Laboratory of Eco-Hydraulics in Northwest Arid Region, Xi’an University of Technology, Xi’an 710049, China
3. Institute of Water Resources and Hydro-Electric Engineering, Xi’an University of Technology, Xi’an 710049, China
Abstract
In the construction of urban underground shield tunnels, uneven deformation can easily occur when the shield passes through soft soil and other poor strata. Such deformation has a significant impact on surface settlement and may cause potential safety hazards to the surrounding existing buildings, directly affecting the safety of urban operation. When simulating and predicting surface settlements, the small-strain soil hardening model can more accurately characterize the mechanical parameters of soil. Nevertheless, its parameters are numerous and complicated to determine accurately, so parameter inversion is needed to determine the accurate parameters of the soft soil layer in order to more accurately predict the surface settlement. This study uses the EFAST method to analyse the sensitivity of the HSS model parameters of soft soil strata. It is determined that the parameters that have the most significant impact on the surface settlement are the reference tangent modulus, rebound modulus, and effective cohesion. Then, XGBoost’s fast calculation speed and high precision of SSA inversion are used to inverse and optimize the parameters with high sensitivity. Finally, according to the parameters of the soft soil layer obtained from inversion and measured data, the settlement deformation and safety behaviour of existing buildings are analysed. Combined with the actual shield tunnel project in a city along a river, the inversion calculation shows that the overall average error of the transverse monitoring section is 1.04 mm, and the average maximum error of each monitoring point in the overall shield process is 2.87 mm. The prediction effect is significantly improved compared with the original parameters. The accuracy of the inversion of soil layer parameters is verified from the perspective of time and space. The average settlement of the river embankment foundation is 2.5 mm. Compared with the original parameter data, the prediction results have been greatly improved, and the settlement deformation results are more consistent with the measured data.
Funder
National Natural Science Foundation of China
General Program of Natural Science Basic Research Program of Shaanxi
Shaanxi Provincial Education Department
Innovation Capability Support Program of Shaanxi
Reference44 articles.
1. Present Situations of Development and Utilization for Underground Space in Cities and New Viewpoints for Future Development;Lei;Chin. J. Undergr. Space Eng.,2019
2. Influence of Construction Sequence and Lagging Distance on Ground Movements Induced by Two Overlapping Shield Tunnels;Fan;J. Tianjin Univ. (Sci. Technol.),2022
3. Evaluation of risk assessment procedures for buildings adjacent to tunnelling works;Clarke;Tunn. Undergr. Space Technol.,2014
4. Analysis of existing railway deformation caused by double shield tunnel construction in soil–rock composite stratum;Jiao;Energy Rep.,2023
5. Assessment of optimum settlement of structure adjacent urban tunnel by using neural network methods;Azadi;Tunn. Undergr. Space Technol.,2013