三轴压缩下含瓦斯水合物煤体力学特性的离散元研究

Discrete Element Study on Mechanical Properties of Gas Hydrate Bearing Coal under Triaxial Compression

瓦斯水合固化防突技术能有效强化煤体力学特性,减弱煤与瓦斯突出危险性,但荷载作用下瓦斯水合物-煤介质体系力学特性演化机理不清晰,制约了瓦斯水合固化防突技术的发展。因此,以含瓦斯水合物煤体为研究对象,基于离散元法,建立了含瓦斯水合物煤体数值模型,分析了刚度比、水合物颗粒含量等参数取值对应力-应变曲线的影响,揭示了三轴压缩过程含瓦斯水合物煤体接触力链变化规律。研究表明:数值模拟能较好地模拟试验结果;在模拟过程中,刚度比k_(n)/k_(s)>1的弹性模量总体上比k_(n)/k_(s)≤1的弹性模量大;随切向黏结应力及水合物颗粒含量的增加,应力-应变曲线逐渐由应变硬化向应变软化转变;在加载过程中,外力主要由强力链来承载,方向与外部荷载的方向平行;弱力链对强力链起到支撑作用,方向主要沿水平方向。

Coal and gas outburst prevention technology based on the hydrate method can effectively strengthen the mechanical properties of coal and reduce the risk of coal and gas outburst.However,the evolution mechanism of the mechanical properties of gas hydrate bearing coal under loading is not clear,which restricts the development of coal and gas outburst prevention technology based on the hydrate method.Therefore,takes gas hydrate bearing coal as the research object.Based on the discrete element method,a numerical model of gas hydrate bearing coal is established.And the influence of stiffness ratio,hydrate particle content and other parameters on the stress-strain curve is analyzed.The change law of the contact force chain of gas hydrate bearing coal is revealed during triaxia compression.The research shows that the numerical simulation can better simulate the test results During the simulation,elastic moduli with stiffness ratio k_(n)/k_(s)>1 are generally larger than elastic modul with k_(n)/k_(s)≤1.With the increase of tangential bonding stress and hydrate particle content,the stressstrain curve gradually changes from strain hardening to strain softening.During the loading process,the external force is mainly carried by the strong chain,and the direction is parallel to the direction of the external load.The weak chain supports the strong chain,and the direction is mainly in the horizontal direction.