The shutdown of earth pressure balance (EPB) shield tunneling in gravel stratum can easily lead to significant unexpected ground deformation. In order to study the response of gravel strata during shield shutdown and the characteristic change of soil state in the chamber, this paper establishes a coupled Eulerian-Lagrangian finite element method (CEL-FEM) coupling analysis model that reflects the interaction between the spoiled soil and gravel strata. The plastic flow parameters of CEL spoiled soil are calibrated using the slump method, and a quantitative relationship between the slump value, plastic flow parameters, equivalent coefficient of loosening, and excavation face support pressure is established. The reliability and applicability of CEL method in the simulation of shield shutdown are verified by the field measurements. Results show that: (1) The chamber's soil equivalent loose coefficient is inversely proportional to the soil slump value which is related to soil's plastic flow parameters. (2) The shield shutdown in gravel strata has a more significant impact on the deep strata displacement than on the surface. (3) During the shield shutdown stage, the chamber pressure should be dynamically adjusted based on the soil deformation characteristics, and an increase of 16% could result in a stable rebalance.

The expansion of a thick-walled hollow cylinder in soil is of non -self -similar nature that the stress/ deformation paths are not the same for different soil material points. As a result, this problem cannot be solved by the common self -similar -based similarity techniques. This paper proposes a novel, exact solution for rigorous drained expansion analysis of a hollow cylinder of critical state soils. Considering stress -dependent elastic moduli of soils, new analytical stress and displacement solutions for the nonself -similar problem are developed taking the small strain assumption in the elastic zone. In the plastic zone, the cavity expansion response is formulated into a set of first -order partial differential equations (PDEs) with the combination use of Eulerian and Lagrangian descriptions, and a novel solution algorithm is developed to ef ficiently solve this complex boundary value problem. The solution is presented in a general form and thus can be useful for a wide range of soils. With the new solution, the non -self -similar nature induced by the finite outer boundary is clearly demonstrated and highlighted, which is found to be greatly different to the behaviour of cavity expansion in in finite soil mass. The present solution may serve as a benchmark for verifying the performance of advanced numerical techniques with critical state soil models and be used to capture the finite boundary effect for pressuremeter tests in small -sized calibration chambers. (c) 2024 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V. This is an open access article under the CC BY -NC -ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).