Experiment on Mine Ground Pressure of Stiff Coal-Pillar Entry Retaining under the Activation Condition of Hard Roof

Table 1

Materials used in the physical model.

Lithology	UCS of prototype (MPa)	UCS of model (kPa)	Sand (kg)	Calcium carbonate (kg)	Gypsum (kg)	Amounts (kg)	Water (L)
Mudstone group 1	35.27	144.06	70.31	7.03	7.03	84.38	9.38
Medium sandstone	70.09	286.30	158.20	15.82	36.91	210.94	23.44
Mudstone group 2	35.27	144.06	585.94	58.59	58.59	703.13	78.13
Fine sandstone	74.61	304.81	189.84	18.98	44.30	253.13	36.16
Mudstone group 3	35.27	144.06	386.72	38.67	38.67	464.06	51.56
Limestone	71.83	293.42	142.38	14.24	33.22	189.84	27.12
Coal seam 15	24.83	101.41	79.98	5.71	5.71	91.41	10.16
Mudstone	29.71	121.35	120.54	10.04	10.04	140.63	15.63