Journal Article

Mechanical Behavior of Shale at Different Strain Rates

Yang, Chunhe, Gutierrez, Marte, Hou, Zhenkun, Almrabat, Abdulhadi, Ma, Shuqi

2019

Overview

The strain rate-dependent mechanical behavior of shale is characterized using triaxial compression tests under a constant confining pressure of 50 MPa and axial strain rates \\[ _1\\] ranging from 5 × 10−6 s−1 to 1 × 10−3 s−1. This study is conducted on the Longmaxi shale from Dayou in China, which is predominantly composed of brittle minerals including quartz (55%), albite (15%) and cristobalite (3%). The experimental results show that higher axial loading strain rates \\[ _1\\] lead to higher elastic modulus and higher peak shear strength, both following exponential relationships with \\[ _1\\]. When \\[ _1 1 10^ - 5 s^ - 1\\], failure results in a single linear fracture, whereas a more complex multiple crisscrossing fracture network is formed when \\[ _1 1 10^ - 4 s^ - 1\\]. Failure in shale specimens can be described by a damage parameter \\[D\\], which is strongly affected by the axial strain \\[_1s\\]. In addition, the strain rate \\[ _1\\] had different effects on \\[D\\], which also depends on axial strain \\[_1s\\]. Energy accumulation and dissipation are also closely related to \\[ _1\\] with the total absorbed energy \\[U_A\\], the recoverable elastic strain energy \\[U_A^e\\] and the dissipated energy \\[U_A^d\\] at the peak stress increasing with \\[ _1\\]. As for the total energy accumulation \\[U_A\\], the recoverable elastic energy \\[U_A^e\\] decreases while the dissipated energy \\[U_A^d\\] increases with increasing strain rate.

• Publisher: Springer Nature B.V
• Subject: Accumulation / Axial strain / Compression / Confining / Cristobalite / Elastic recovery / Energy / Mechanical properties / Minerals / Modulus of elasticity / Sedimentary rocks / Shale / Shales / Shear strength / Strain / Strain rate / Triaxial compression tests