O型棚支护抵抗冲击地压等级计算方法

Calculation method of rock burst resistance grade of O-shaped shed support

O型棚支护具有良好的护表性,常被用于冲击地压巷道控制围岩破碎区的变形与破坏,但O型棚支护参数设计主要依靠经验法,缺乏相应的理论依据和科学计算方法。基于O型棚支护的工作原理,得到O型棚支护特性曲线及最大支护阻力,发现O型棚支护的最大支护阻力与U型钢的型号及壁后填充参数密切相关;通过理论分析冲击应力波在煤岩介质中传播规律,发现冲击地压对巷道支护的作用力大小主要取决于巷道附近围岩质点最大加速度,由此提出一种评价冲击地压等级的新指标——冲击地压破坏系数Kg,用于冲击地压巷道O型棚支护参数设计;利用多层结构法计算得到围岩冲击载荷与O型棚支护阻力的关系以及震动能量与冲击地压破坏系数关系,进而得到O型棚支护可抵抗冲击地压等级计算公式,并发现O型棚支护抵抗冲击地压等级大小主要受冲击地压能量大小、冲击源距巷道距离、围岩煤岩介质力学性质等因素影响。根据抚顺老虎台矿冲击地压特征及发生规律,优化了冲击地压巷道O型棚支护参数,通过现场应用效果对比发现,优化设计参数后的O型棚支护抵抗冲击地压等级明显提高,并成功抵抗住多次冲击事件,避免了支架塑性变形与破坏,说明了O型棚支护抵抗冲击地压等级计算方法具有较好的可信度。通过计算发现,普通36U型钢O型棚支护最大可抵抗中等冲击的冲击地压,因此对具有强烈冲击危险的巷道,还需增加液压支架进行补偿支护,提高巷道支护抗冲击能力。

The O-shaped shed support has good surface protection,and is often used to control the deformation and damage of surrounding rock fracture area in the rock burst roadway.However,the design of O-shaped shed support parameters mainly depends on the empirical method,which lacks the corresponding theoretical basis and scientific calculation method.Based on the working principle of O-shaped shed support,the characteristic curve and the maximum support resistance of O-shaped shed support are obtained.It is found that the maximum support resistance of O-shaped shed support is closely related to the type of U-shaped steel and the filling parameters behind the wall.Through the theoretical analysis on the propagation law of the shock stress wave in the coal and rock medium,it is found that the magnitude of the impact force of the rock burst on the roadway support mainly depends on the maximum acceleration of the surrounding rock mass near the roadway,so a new index of evaluating the grade of rock burst,i.e.,the failure coefficient Kg of rock burst,is proposed.It is used for the design of the supporting parameters of the O-shaped shed in the roadway under the impact of ground pressure.The relationship between the impact load of surrounding rock and the supporting resistance of the O-shaped shed,the vibration energy and the failure coefficient of the impact ground pressure are calculated by using the multi-layer structure method,and then the calculation formula of the level of the impact ground pressure that the O-shaped shed can resist is obtained.It is found that the grade of rock burst resistance of O-shaped shed support is mainly affected by the magnitude of rock burst energy,the distance between the impact source and the roadway,and the mechanical properties of surrounding rock and coal medium.Through the comparison of field application results,it is found that the grade of resistance to impact the ground pressure of O-shaped shed support after the optimization of design parameters is significantly improved.The optimized O-shaped shed support successfully resists multiple impact events and avoids the plastic deformation and damage of support,which shows that the calculation method of O-shaped shed support’s resistance to rock burst has a high reliability.Through the calculation,it is found that the common 36U steel O-shaped shed support can resist the impact ground pressure of medium impact.Therefore,for the roadway with strong impact risk,it is necessary to add hydraulic support for compensation support to improve the impact resistance of roadway support.