基于“三铰拱-弹簧”模型的复合底板巷道非对称底鼓机制及卸压控制

Asymmetric floor heave mechanism and pressure relief control in composite bottom-slab roadways based on the“three-hinged arch-spring”model

为解决动压巷道非对称底鼓变形难题和诱发动力学事件的隐患,基于巷道非对称变形几何形态和受力特征建立“三铰拱-弹簧支撑”模型,分析系统能量的耗散特征和系统总势能函数的尖点突变失稳的充要判别条件,研究表明底板在平衡曲线变形为两种形式,当沿路径I时变形是线性渐进的,不会发生大能量释放的动力学事件;当沿II路径时,变形是非线性的突发式底鼓,其中巷道底板的岩性、尺寸及侧应力是影响系统失稳的关键因素,可通过卸消压力方式来防治底板动力学事件发生。因此,提出切顶卸压底鼓控制技术,分析卸压机制,并在曹家滩煤矿开展卸压试验。研究表明,切顶是通过改变悬顶板支座形式来缩短顶板的垮落步距,进而来实现采场横、纵向压力卸载和集聚能量的释放,且横向压力卸压较纵向更为明显,进而有效控制了巷道底鼓变形。

In order to solve the problem of asymmetric floor heave of roadway and the potential of inducing kinetic events in dynamic pressure roadways,this paper established a“three-hinged arch-spring support”model based on the geometry and force characteristics of asymmetric roadway deformation,and analyzed the energy dissipation characteristics of the system and the sufficient discriminatory conditions for abrupt destabilization at the cusp of the total potential energy function of the system.The research showed that the deformation of the equilibrium curve takes two forms when along path I,the deformation is linear and progressive,and no large energy release kinetic event occurs.When along path II,the deformation is a non-linear and abrupt floor heave of roadway,where the lithology,dimensions and lateral stress of the roadway bottom are the key factors affecting the system instability,and the floor slab kinetic event can be prevented by pressure relief.Therefore,the technique of cutting the roof to unload the floor heave of roadway is proposed,the mechanism of pressure unloading is analyzed,and pressure unloading tests are carried out in the Caojiatan coal mine.The results prove that cutting the roof is done by changing the support form of the overhanging roof plate to shorten the collapse step of the roof plate,thus realizing the horizontal and vertical pressure unloading and the release of the collected energy in the quarry,and the horizontal pressure unloading is more obvious than the vertical,thus effectively controlling the deformation of roadway floor.