Study on control technology of composite roof roadway in soft roof,soft coal and soft floor coal seam

In order to solve the engineering problems of local support structure deformation, damage and roadway damage during the bolt support process of composite roof tunnel in three soft coal seams in Huainan mining area, the research methods of field test, theoretical analysis, numerical simulation and engineering verification are adopted. Supporting failure analysis and the surrounding rock control mechanism of bolt support in composite roof roadway in three-soft coal seam are analyzed, in order to realize the stable control of the bolt support to the composite roof roadway in three-soft coal seam, the following four aspects should be emphasized in the design and management of the bolt support: ①the "pressure arch" structure in the shallow surrounding rock should be built with reasonable length of anchor rod and supporting attachment.②the anchor cable should be placed in a stable rock layer to play a "suspension" role.③the weak part of the roadway should be strengthened. ④reasonable construction parameters should be designed in order to coordinate the deformation of the surrounding rock mass and the support body. Taking the bolt support of composite roof roadway of No.13-1 three-soft coal seam of Guqiao coal mine as the engineering background. In the application concept of bolt support control, based on the guiding ideology of the new Austrian law dynamic information construction process, a three-soft coal seam composite roof roadway control technology system consisting of design, construction, monitoring, evaluation and optimization was constructed. In the aspect of bolt support parameter management, the dynamic management method of bolt parameters was established from the aspects of initial parameter design, parameter inspection, timely adjustment of field parameters and reinforcement of weak parts. In the aspect of bolt construction management, starting from the construction quality standardization system construction and support safety measures, the construction technology of bolt construction management is constructed. Starting from the construction quality standardization system and the support security measures, the security technology of bolt construction management is constructed. The anchoring force and bearing capacity index of the bolt were analyzed by the second order moment JC method to reflect the reliability of the bolt support structure. Based on the support weak structure, the reliability of the original support scheme was optimized.It is considered that the reliability index β of the composite roof support of the three soft seams in Huainan mining area should be 1.0~1.5.