Mechanism and support measures of floor heave mainly caused by horizontal extrusion stress in soft rock roadway

Floor heave is one of the most difficult problems of soft rock roadway supporting in coal mines. A serious floor heave have occurred when the west wing track roadway of Tingnan coal mine was being constructed, the maximum value reached to 50 cm, which impacted the normal application of roadway severely. The article involved engineering geology, soft rock engineering mechanics and clay mineralogy etc, employed the ways of study on engineering geomechanics, laboratory testing on properties of rock mass, and combined with FDM 3D numerical simulation, and deeply researched the deformation mechanism and generating process of floor heave, it indicated clearly that the major influencing factor that led to floor heave was the horizontal extrusion stress, and the secondary ones were floor surrounding rock with high content of swelling clay minerals and soaking effect on floor rock. Thus the deformation mechanism was compound type of floor heave caused by the combined action of plastic extrusion and swelling. Aimed at the above-mentioned mechanism, a new support measures would be provided with inverted arch and floor bolt to control the floor heave. Project protice has shown good results of new supporting have been obtained with expected effects, and controlled the floor heave effectively.