Abstract: As the buried depth of TBM-excavated tunnels increases, how to reduce the risk of TBM shield jamming becomes an urgent problem. Based on the Newton iteration and the finite element method, an inverse method for the identification of the interaction loads between shield surface and surrounding rock mass is proposed. The error between measured and calculated strain values of the observation points on the internal shield surface is set as the objective function, and the Moore-Penrose inverse is introduced to solve the inverse equation. Meanwhile, a finite partition strategy for the external shield surface is adopted, then the nodal loads of partitioned areas are defined as the inverse parameters, which is convenient for the control of the number of the inverse parameters. The loads within each partitioned region are obtained by the interpolation of the nodal loads, and the fitting of the arbitrary distributed loads acting on the external shield surface is realized. The results of numerical examples show that: the proposed inverse method is featured with high computational efficiency, and good immunity to observation error; the load distribution law and the magnitude of friction on the external shield surface can be identified effectively by performing the inverse analysis. To a certain extent, it can provide guidance for safe tunneling, jamming warning and accident treatment. Furthermore, the proposed method can also be extended to the low-dimensional cases and provide reference for the inverse analysis of other structure loads or physical parameters.

Key words: tunnel boring machine(TBM), load identification, inverse analysis, Newton iteration