Abstract
Abstract Creep is a fundamental time-dependent property of rock. As one of the main surrounding rocks of underground engineering, layered siltstone is governed by creep to a great extent because of special structure. Based on the structural characteristics of layered siltstone, a viscoelastic–viscoplastic model was proposed to simulate and present its creep property. To verify the accuracy of the model, governing equation of the viscoelastic–viscoplastic model was introduced into finite element difference program to simulate a series of creep tests of layered siltstone. Meanwhile, creep tests on layered siltstone were conducted. Numerical simulation results of the viscoelastic–viscoplastic model were compared with creep test data. Mean relative error of creep test data and numerical simulation result was 0.41%. Combined with Lyapunov function, the radial basis function (RBF) neural network trained with creep test data was adopted. Mean relative error of creep test data and RBF neural network data was 0.57%. The results further showed high accuracy and stability of RBF neural network and the viscoelastic–viscoplastic model.
Highlights
Safety construction is one of the main tasks to ensure underground engineering
Ei where Ei is the creep strain of rock samples obtained by creep test, Pi is the creep strain of rock obtained by radial basis function (RBF) neural network or the viscoelastic–viscoplastic model, and N is the number of data collection points
Our studies established the viscoelastic–viscoplastic model and trained the RBF neural network to reveal the effect of layered structure on creep behavior of layered siltstone, and the creep test results suggested stability and accuracy of the model and the RBF neural network
Summary
Safety construction is one of the main tasks to ensure underground engineering. The continuous creep of disturbed surrounding rock can lead to large deformation and even space closure of underground chamber, which must be taken into account in the design and stability analysis of underground engineering. With the deepening of researches, characteristics of rock in different mechanical environment are discovered, and the classical viscoelastic model shows its limitations In this case, a series of rheological models have been proposed through in-depth studies and theoretical breakthroughs [7,8,9,10,11], which can simulate creep behaviors of rock and have a wider range of application [12]. Bozzano et al [16] constructed a multi-model analysis method based on morphological evolution simulation to study the creep behavior and failure mechanism of rock slope. Rahimi and Hosseini [31] carried out a triaxial creep experiment on rock salt and studied the influence of confining pressure, deviating stress, and strain rate on the creep behavior of rock salt. Based on the creep test data, error analysis was conducted to verify scientific nature and accuracy of the proposed model
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