Abstract
To solve the classical problem that the Mohr–Coulomb yield criterion overestimates the tensile properties of geotechnical materials, a modified Mohr–Coulomb yield criterion that includes both maximum tensile stress theory and smooth processing was established herein. The modified Mohr–Coulomb constitutive model is developed using the user-defined material subroutine (UMAT) available in finite element software ABAQUS, and the modified Mohr–Coulomb yield criterion is applied to construct a numerical simulation of a shaking table model test. Compared with the measured data from the shaking table test, the accuracies of the classical Mohr–Coulomb yield criterion and the modified Mohr–Coulomb yield criterion are assessed. Compared to the shaking table test, the classical Mohr–Coulomb model has a relatively large average error (−6.98% in peak acceleration values, −8.47% in displacement values, −23.93% in axial forces), while the modified Mohr–Coulomb model has a smaller average error (+2.71% in peak accelerations value, +3.19% in displacements value, +7.56% in axial forces). The results of numerical simulation using the modified Mohr–Coulomb yield criterion are closer to the measured data.
Highlights
Changning earthquake (Ms 6.0, 2019) show that the tunnels within the Sichuan Basin are threatened by highintensity earthquakes. erefore, studies of the seismic performance of underground structures should receive more attention.ere are three main types of approaches for the analysis of seismic performance of underground structures: field investigations, model tests, and numerical simulations [8,9,10,11,12,13]
Introduction to the Shaking Table Test. e primary objective of the shaking table test was to test how the vibration-absorptive material protects a tunnel in a fault zone [21]. e overall layout of the shaking table is shown in Figures 4 and 5. e detailed accelerometer monitoring plan is presented in Table 1. e rock surrounding the tunnel between the two fault zones is placed on a movable platform with 10 cm-thick foam pieces on both the left and right sides
E prototype of the model is the Longxi tunnel which was highly damaged in the Wenchuan earthquake. e input wave of the shaking table is part of the east and west vector components of the Wolong seismic waves which is widely used in simulating tunnel dynamic response [21]. e original seismic wave lasts for 180 s, and the peak acceleration value is 0.98 g. e input wave occurs at 20 s to 110 s
Summary
Ere are three main types of approaches for the analysis of seismic performance of underground structures: field investigations, model tests, and numerical simulations [8,9,10,11,12,13]. E classical Mohr–Coulomb yield criterion is the most widely used constitutive model in geotechnical mechanics. It focuses on the response of brittle materials to shear stress and normal stress. Jia et al combined the classical Mohr–Coulomb theory with the maximum tensile stress theory, which uses a parameter m to reduce the yield stress but leaves no definition of the parameter m [20]. Based on these previous studies, a constitutive model with the tensile strength replacing the parameter m in Jia’s model was developed. Based on these previous studies, a constitutive model with the tensile strength replacing the parameter m in Jia’s model was developed. e modified model was applied to the dynamic numerical simulation of underground structures, and its advantages were compared with those of the classical Mohr–Coulomb model
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