不等侧压下煤岩力学变形特性及声发射时空特征

MECHANICAL AND DEFORMATION PROPERTY AND ACOUSTIC EMESSION CHARACTERISTICS OF COAL ROCK UNDER UNEQUAL BILATERAL CONFINING PRESSURE

通过煤岩的无侧限压缩试验测得其力学参数后,采用颗粒流软件和编制的Fish程序获得煤岩细观力学参数,而后进行双向不等侧压煤岩试验,分析研究煤岩变形、声发射和损伤特征,获得以下结论:随着侧压比增加,煤岩刚度角略增大,脆度角增大,强化角保持一定值,软化角先增大后减小;侧压比对煤岩的线性体缩阶段没有影响,对线性扩容阶段影响明显,对非线性扩容阶段影响显著。在非线性扩容阶段,低侧压比仍保持线性扩容,而高侧压比煤岩则急剧扩容失稳破坏;声发射最大强度与峰值应力并不对应,具有一定的滞后性,侧压比对声发射的滞后效应基本没有影响,声发射最大强度对应应力与峰值应力之比值大致在0.92左右;侧压比小时煤岩沿着单一剪切面发生剪切破坏,侧压比大时煤岩呈现X型共轭剪切破坏,且随着侧压比的增加,煤岩破坏的主控破裂面宽度加大,并逐渐形成破碎带,破碎带内煤岩呈粉碎性破坏状态。

The mechanical parameters of coal rock were measured through unconfined compression experiment , then the mesomechanical parameters of coal rock were obtained by particle flow code and Fish program and experiments were carried out under unequal bilateral confining pressure .It was analyzed the mechanical and deformation property and acoustic emission characteristics in the failure process of coal rock .Some main research results were as follows:with the increasing of confining pressure ratio , coal rock stiffness angle increased , slightly, brittleness angle increased , strengthening angle kept constant , softening angle first increased and then decreased;Confining pressure ratio had no effect on volumetric strain in linear compression stage , obvious effect on the linear expansion stage and significant effect on the nonlinear expansion stage .In nonlinear expansion stage , coal rock volumetric strain still was linear on lower confining pressure ratio while coal rock rapidly expanded and instability on higher confining pressure ratio .The maximum intensity of acoustic emission lagged behind the peak stress , confining pressure ratio had no effect on the lag , the ratio of stress at acoustic emission maximum strength to peak stress was about 0.92;On lower confining pressure ratio, shear failare occured along a single shear surface of coal rock , on higher confining pressure ratio X conjugate shear failure occured .Main failure surface width increased and developed into fracture zone with the increasing of confining pressure ratio , the coal rock in the zone was a crushing failure state .