Taking second shaped coal samples as research object

the coupling relationship between characteristics of gas flow and lateral strain of coal containing gas under triaxial loading is studied by self-developed triaxial servo-controlled seepage equipment for thermo- fluid-solid coupling of coal containing gas. The results show: Poisson ratio defined by elastic mechanics can not accurately express the characteristics of axial strain and lateral strain of coal containing gas; the relationship can be properly expressed by quadratic function. Characteristics of gas flow velocity is showed by the law that firstly rapid decreased then slowly increased in restoration stage of lateral strain caused by preloading. Gas flow velocity can be showed by the law of monotonic slowly increased in transformable stage from lateral compressive strain to dilated strain; and there is a special internal structure critical state point where the gas flow velocity is the smallest. The gas flow velocity of coal containing gas at initial state of lateral compressive strain is larger than it at end state of lateral dilated strain.