Structural Design and Experimental Study on Mechanical Properties of Sand Column Support

To solve the problem of insufficient support strength caused by unreasonable structure design of roadway side support of gob-side entry retaining in Dongda Coal Mine, and by means of preliminary test of bearing capacity, theoretical calculation and mechanical experiment of sand pillar, the optimization design of supporting structure of gob-side entry retaining was carried out. The results show that when the ratio of sand and stone material filled with sand column is 1∶1 and the filling material is vibrated by adding water, the density of filling material reaches the maximum and the stability of sand column is optimal; when the pressure gauge reading is 32 MPa, the lower part of the sand column is in the basic fracture state and the water-sand column can bear more ultimate load than the water-sand column. It is proved that the optimized sand pillar support body can meet the support strength requirements of gob-side entry retaining and improve the production efficiency.