基于岩体安全系数的巷道协同锚固支护方法研究

Study on the method of roadway cooperative anchor support based on rock mass safety factor

为解决煤矿洞室锚固支护参数选取难题,提出基于不同安全系数下围岩塑性区分布特征的支护参数选取方法。通过离散元数值模拟技术,将岩块及结构面中的黏聚力、内摩擦角,按照折减系数进行赋值计算,得到不同安全系数情况下围岩失稳区域范围。根据支护及现场实际要求,分析锚固段位置与安全系数之间的关系,从而实现协同支护,定量获得支护参数。研究结果表明:依据强度折减方法,能够有效识别巷道交叉点等复杂洞室风险区域,并可以得到各部围岩安全系数的分布特征。在支护设计方案中,应该保障短锚杆锚固段在安全系数大于1的区域,顶部及两帮腰部等重要部位的长锚索锚固端设置在安全系数大于2的区域,中隔墙采用双控锚索其加固范围为安全系数小于1.3区域。协同支护加固下,实测交叉洞室围岩最大变形值为2.9 cm,矩形回采巷道变形最大值27.5 cm,数值计算结果与现场实测结果最大误差仅为0.5 cm,均表明该支护设计方法可靠性较强,为煤矿巷道洞室支护参数定量化设计提供科学依据。

In order to solve the problem of selecting the parameters of anchoring support in coal mine caverns,a method for selecting support parameters based on the distribution characteristics of surrounding rock plastic zone under different safety factors is proposed.Through the discrete element numerical simulation technology,the cohesion and internal friction angle in the parameters of rock block and structural plane are assigned and calculated according to the reduction coefficient.The range of surrounding rock instability region under different safety factors is obtained.According to the support and the actual requirements of the engineering,the relationship between the position of the anchorage section and the safety factor is analyzed,to achieve collaborative and quantitatively support parameters.The results show that according to the strength reduction method,the risk areas of complex caverns such as roadway intersections can be effectively analyzed,and the distribution characteristics of the safety factor of surrounding rocks can be obtained.In the support design scheme,the anchorage section of the short bolt should be ensured in the area with a safety factor greater than 1.For important parts such as the top of the roadway and the waist of the two sides,the anchoring end of the long anchor cable is set in the area with a safety factor greater than 2.The middle partition wall adopts double control anchor cables,and its reinforcement range is the area with a safety factor less than 1.3.Under the reinforcement of cooperative support,the measured maximum deformation value of the surrounding rock of the intersection tunnel is 2.9 cm,the maximum deformation value of the rectangular mining roadway is 27.5 cm,and the maximum error between the numerical calculation result and the field measurement result is only 0.5 cm,which shows that the support design method is highly reliable,and provides a scientific basis for the quantitative design of the support parameters of the coal mine tunnel.