Research on lengthening bolt roof support system performance in largely deformed roadway

In order to solve technical problems of largely deformed roadway,such as high support cost and poor support effect,a new style lengthening bolt was researched and developed. The paper studied deformation and failure feature of largely deformed roof,and analyzed force and deformation characteristic of lengthening bolt by comparison with ordinary bolt and traditional cable. Besides,the constitutive model of surrounding rock-support system was established,then, the lengthening bolt roof support system was put forward and successfully applied in 5203 ventilation roadway in Wujiagou Mine,which effectively control the sustainable deformation of roadway roof. The research results show that maximum elongation and breaking load of 4 m lengthening bolt respectively are 685 mm and 195 kN. Furthermore,the lengthening bolt not only gives full play to its high elongation,but ensures high support resistance. Besides,both of stability and support strength of lengthening bolt roof support system are superior than roof cable support system in late period. Field observation results show that the subsidence amount decreases more than 33% when the roof is supported by lengthening bolt roof support system,and the proportion of those lengthening bolt with 160-180 kN support strength is almost 87. 5%,which achieves the goal of strong support and yield pressure.