Numerical studies of floor heave control by the rock bolts reinforcement technology in retained gob-side gateroad

The effectiveness of modified rock bolts reinforcement technology for floor heave control in gob-side entry retaining was studied in this paper. A finite-element numerical simulation was used to analyse stress-strain state of surrounding rocks before and after immediate floor reinforcement with six floor support schemes. It was found that after immediate floor reinforcement with rock bolts with diameter 32 mm and 96 mm, floor heave in retained gob-side gateroad reduces by 2.94 – 3.6 times respectively. The modification of rock bolt reinforcement scheme by the additional installation of piles in the entry corners was proposed. Piles installation significantly reduces the zone of horizontal and vertical post-peak strains in the gateroad floor. The best variant among compared ones is a floor support scheme with two corner piles, 1 m and 2 m long. With this scheme, floor heave decreases by 3.05 times. The comparison of the materials costs of the floor support schemes were performed. As a result, the most effective floor support scheme was proposed and prospects for the further progress of floor reinforcing technologies were outlined.