Mechanical properties and nonlinear deformation description model of cement stone

Abstract

The cement stone exhibits obvious plastic deformation performance under confining pressure, and a simple linear elastic model cannot describe the entire stress-strain process. In this work, the mechanical properties of oil well cement stone are tested and analyzed from different aspects by uniaxial compression test and triaxial stress test of typical cement stone. Based on obtaining the mechanical properties of cement stone and referring to the nonlinear elastic constitutive theory of concrete, an uncoupled secant bulk modulus and secant shear modulus total stress-strain description equation is constructed to describe the nonlinearity deformation properties of cement stone. The research results show that cement stone is a pressure-sensitive material, and its mechanical properties are greatly affected by confining pressure. The linear elastic constitutive model is a simplified and approximate description of the deformation process of cement stone. Like concrete, cement stone has functional relationships between the secant bulk modulus and octahedral normal strain, as well as the secant shear modulus and octahedral shear strain of different cement stones. Substituting the fitted function into the linear elastic constitutive model, the nonlinear deformation description model of cement stone can be obtained, which can effectively describe the nonlinear stress-strain characteristics of cement stone, especially in the case of confining pressure.