Experimental investigation and constitutive model for lime mudstone.

Junbao Wang,Jinxing Lai,Zhanping Song,Baoyun Zhao,Xinrong Liu

doi:10.1186/s40064-016-3297-8

Abstract

In order to investigate the mechanical properties of lime mudstone, conventional triaxial compression tests under different confining pressures (0, 5, 15 and 20 MPa) are performed on lime mudstone samples. The test results show that, from the overall perspective of variation law, the axial peak stress, axial peak strain and elastic modulus of lime mudstone tend to gradually increase with increasing confining pressure. In the range of tested confining pressure, the variations in axial peak stress and elastic modulus with confining pressure can be described with linear functions; while the variation in axial peak strain with confining pressure can be reflected with a power function. To describe the axial stress–strain behavior in failure process of lime mudstone, a new constitutive model is proposed, with the model characteristics analyzed and the parameter determination method put forward. Compared with Wang’ model, only one parameter n is added to the new model. The comparison of predicted curves from the model and test data indicates that the new model can preferably simulate the strain softening property of lime mudstone and the axial stress–strain response in rock failure process.

Highlights

With the development of economy, a large number of rock projects are emerging
The axial stress–strain curve gradually bends to the vertical axis with the increase of strain. (b) Stage II: elastic deformation
The deformation of lime mudstone shows linear regular growth with increasing stress, and its axial stress–strain curve is approximate to a straight line. (c) Stage III: plastic deformation

Summary

Introduction

With the development of economy, a large number of rock projects are emerging. To guarantee the safety of these projects, it is very important to study the mechanical properties of rock (Singh, et al 2015; Nadimi et al 2011; Wang et al 2014; Yang et al 2015; Nadimi and Shahriar 2014; Chen et al 2016a, b; Lai et al 2016), which as a kind of natural geological material contains many flaws (for instance, joints, micro cracks, faults, etc.). Based on the analyses on test results, a new constitutive model is proposed to simulate the axial stress–strain behavior of lime mudstone in this study.

Results

Conclusion