Study on Floor Heave Characteristics and the Control Method of Gob-Side Entry Driving in Weakly Cemented Soft Rock

Abstract

Aiming at the problems of large deformation, long duration, and difficult control of floor heave in gob-side entry driving in weakly cemented soft rock, this paper takes the weakly cemented soft rock mining area in Western China as the engineering background, and studies the characteristics and mechanism of floor heave in gob-side entry driving in weakly cemented soft rock by means of a field investigation, physical component analysis, mechanical property tests of the surrounding rock, and the stress monitoring of the surrounding rock. The classification control method of floor heave is put forward, and field tests are conducted. The results show that: (1) The floor heave characteristics of the dynamic change in the floor heave peak position of gob-side entry driving from the coal pillar side to the mining side are obtained through field observation. (2) Based on the analysis of field data and laboratory test data, it is concluded that the stability time of the overlying strata in gob-side entry driving is about 8 to 12 months. The main internal cause of roadway floor heave is the low load resistance of weakly cemented soft rock. High stress and strong disturbances are the main power sources of strong floor heave. The mechanism of floor heave affected by dynamic lateral abutment pressure is summarized, and the classification control method of floor heave is proposed. (3) The gob-side entry driving support technologies of “adjusting excavation deployment” and “surrounding rock pressure relief and improving support” are proposed. Through field tests, the floor heave can be effectively controlled.

Experimental Study on the Floor Heave and Failure Process of Rock Samples under Biaxial Step Loading

“…They investigated the relatively hard tuff layers with higher strength and ruled out the possibility of bearing capacity failure. The primary internal factors leading to roadway floor heave in weakly cemented soft rock are high stress and strong disturbances [22]. Currently, research on floor heave mainly focuses on indoor model experiments or numerical simulations of soft rock or soft interbedded pouring samples.…”