ABSTRACT:

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.

INTRODUCTION

When the excavation of roadway has been advanced, the balance of in-situ stress situation of rock mass was destroyed, which lead to the redistribution of stress field, and the surrounding rock would be displaced into roadway. The floor heave is a kind of dynamic phenomenon; it has always been happened in many coal mine, which lead to the decrease in roadway section, and hinder transportation, ventilation and staff operation. There are some coal mines stopping production or canceling construction caused by floor heave, which seriously affect production, and threaten life safety[1].

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