岩土力学2024，Vol.45Issue(2)：385-395,11.DOI:10.16285/j.rsm.2023.1280
不同应力路径下层理煤体力学特性试验研究
Experimental study on mechanical properties of bedding coal under different stress paths
摘要
Abstract
To investigate the mechanical properties and failure characteristics of bedding coal under different stress paths,mechanical tests were conducted using the MTS816 rock mechanics testing system.Coal samples with bedding angles of 0°,30°,45°,60°,and 90° were subjected to tests under three stress paths:conventional triaxial loading,increasing axial pressure unloading confining pressure,and constant axial pressure unloading confining pressure.The study analyzed the influence of stress paths and bedding angles on the strength,deformation,and failure characteristics of the coal samples.The results indicate the following:Under the path of conventional triaxial loading,the stress-strain curves of the coal samples show a nearly linear relationship before reaching the peak point,followed by a rapid drop in stress after reaching the peak.Under the path of increasing axial pressure unloading confining pressure,the axial strain increment ratio exhibits a linear increasing trend as the unloading ratio increases.The circumferential strain increment ratio and volumetric strain increment ratio display a three-stage change characteristic,involving low-speed growth,rapid growth,and stable growth.Under the path of constant axial pressure unloading confining pressure,the axial strain increment ratio,circumferential strain increment ratio,and volumetric strain increment ratio exhibit a two-stage change characteristic,involving low-speed growth and rapid growth.The peak strength and axial peak strain of the coal samples exhibit a V-shaped trend with increasing bedding angle under different stress paths.They initially decrease and then increase,reaching the maximum value at 0° and the minimum value at 60°.As the unloading ratio increases,the deformation modulus of the coal sample initially stabilizes and then rapidly deteriorates.The Poisson's ratio first slowly increases and then exponentially increases.The critical unloading ratio initially increases and then decreases with increasing bedding angle.When the bedding angle is the same,the critical unloading ratio under the path of increasing axial pressure unloading confining pressure is lower than that under the path of constant axial pressure unloading confining pressure.Under the path of conventional triaxial loading,the coal sample undergoes brittle shear failure.However,under the paths of increasing axial pressure unloading confining pressure and constant axial pressure unloading confining pressure,the coal sample exhibits a mixed tensile-shear failure mode.When the bedding angle is 60°,the angle of the main shear fracture surface of the coal sample is almost consistent with the bedding angle.关键词
应力路径/层理煤体/力学特性/破坏特征/卸荷比Key words
stress path/bedding coal/mechanical properties/fracture characteristics/unloading ratio分类
矿业与冶金引用本文复制引用
范浩,王磊,王连国..不同应力路径下层理煤体力学特性试验研究[J].岩土力学,2024,45(2):385-395,11.基金项目
安徽省高校自然科学研究重点项目(No.KJ2021A0457) （No.KJ2021A0457）
安徽省科技重大专项(No.202203a07020010) （No.202203a07020010）
安徽理工大学引进人才科研启动基金(No.2021yjrc15).This work was supported by the Natural Science Research Project of Anhui Educational Committee(KJ2021A0457),the Anhui Provincial Major Science and Technology Project(202203a07020010)and the Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology(2021yjrc15). （No.2021yjrc15）
