The combined support technology of prestressed bolt and cable truss has been widely used in coal mines, but the mechanical interaction between cable truss and surrounding rock hasn't been studied systematically. In this paper, the development process of truss support system is briefly discussed, which is from bolt truss to cable truss, then to high prestress cable truss. Based on the coupling relationship between the high prestress cable truss and the roof rock, the mechanical model of cable truss is built, and the calculation formulas of anchoring force and pre-tightening force are drawn out. The numerical simulation and field observation results of Xinsan mine in Fengfeng Coal Group showed that the design scheme of combined support system including high prestress cable truss was reasonable and effective.
In Chinese coal mines, with the development of mining depth and area, the roadway conditions are becoming more and more complex. The following complicated roadways, such as deep roadways with high ground stress, soft expansion rock roadways, extremely fractured surrounding rock roadways, large-section set-up entry, and roadways strongly suffering from dynamic pressure, have increased rapidly. The common characteristics of these roadways are large surrounding rock deformation and serious support damage, and even roof caving and rib spalling occur, so the roadway security is difficult to be guaranteed (Kang &Wang 2007). The combined bolt and cable truss support technology to be suitable to the complicated roadways develops rapidly and is widely applied in mines.
An earliest truss bolt supporting system composed of two threadbar bolts, two truss brackets, two horizontal threadbars and six tightening nuts appeared in the USA in 1967. About 20 years later, the earliest continuous cable truss supporting system was researched and applied in a shaft inset in Kentucky.