Study on Penetration Features of Coal Rejects During Constant Load Deformation Test Process

Two plans of the deformation vadose test and the vadose test were applied to compare and study the penetration features of the coal rejects during the t ime related deformation process and the penetration coefficients of the coal rejects when the vadose was stabilized under each grade stress level were obtained.The st udy showed that as for the bulk coal rejects with same quality and same initial pile height, due to the differences of the initial pore structures, the displacement value of the rock samples in the vadose test under each grade stress level would all be higher than the displacement of the samples in the deformation vadose test.With the co mpression density and crushing of the rock samples, the order of the pore pressure in the rock samples would be increased from kPa to MPa and under the same vados e velocity, the pressure-time curves of the pore would not be easy to reach stabilized status.Under the same axial stress and vadose velocity the deformation of the roc k sample would have high influences to the penetration coefficient.The study results showed that rockOs penetration coefficient in vadose test is smaller than that is in deformation vadose test.