Study on proportioning of similar materials for overburden rock in underground gasification model experiment

Abstract

In order to provide an accurate theoretical basis for the underground gasification model test of coal, the similar materials ratio of underground gasification’s overburden rock was studied by orthogonal experiment according to the similarity theory. The results show: the fifth group material ratio meets the model test requirements, the mass ratio of sand, cement and gypsum is 6:1:1, and the compressive strength is 1.36MPa; the material strength is most sensitive to sand as compared to cement and gypsum; the compressive strength decreases as the aggregate–binder ratio increases. When the aggregate–binder ratio remains the same, the compressive strength decreases as the cement-gypsum ratio increases; the compressive strength-elastic modulus curve of the specimen increases linearly and conforms to the sandstone fitting curve in the coal-bearing strata; the failure mode of similar materials is mainly shear failure.