巷道群应力场演化特征与支护技术研究

Study on evolution characteristics of stress field and support technology of roadway group

为探究巷道群开挖应力场演化特征,以杜儿坪煤矿南九盘区巷道群为研究对象,采用数值模拟方法研究巷道群分步开挖方式下垂直应力分布特征,结果发现巷道煤柱侧应力集中强度高于实体煤侧,应力峰值位置与巷帮水平距离煤柱侧大于实体煤侧,煤柱宽度影响应力集中强度,煤柱宽度增大则应力集中强度减弱,巷道群开挖处于高应力集中区,巷道支护设计需考虑足够富裕系数。为开发巷道适应性支护技术,采用现场实测方法测量了地应力、围岩强度及结构等基础参数,结果表明:地应力为中等水平,形成以水平应力为主的构造应力场,巷道群开拓方位朝向有利于地应力方向延伸,地应力大小及方向对巷道围岩稳定影响较小;巷道顶板为由砂质泥岩和薄煤线组成的厚度变化不定的复合煤岩顶板,煤岩体强度大小因裂隙发育而剧烈波动不稳定,控制巷道浅部易离层冒落复合煤岩顶板至关重要。基于巷道群应力场分布规律和围岩地质力学评估结论,确定胶带巷采用预应力锚杆锚索支护技术,并提出详细支护方案和支护参数,现场试验取得良好效果,顶底板最大位移87 mm,两帮最大位移81 mm,为煤矿巷道群开挖支护提供了有益指导。

In order to study the evolution characteristics of the stress field of the roadway group excavation,taking the roadway group in Nanjiupan District of Du’erping Coal Mine as the research object,the vertical stress distribution characteristics of the roadway group under the step-by-step excavation method was studied by using the numerical simulation method.The results show that the stress concentration strength on the coal pillar side of the roadway is higher than that on the entity coal side.The peak stress location away from the lane for horizontal distance in coal pillar side is greater than the entity coal side.The coal pillar width influences stress concentration degree.When the width of coal pillar increases,the intensity of stress concentration decreases.The excavation of roadway group is in the area of high stress concentration,and the support design of roadway should consider sufficient abundance factor.In order to develop the technology of roadway adaptive support,the ground stress,strength and structure of surrounding rock were measured by field measurement method.The results show that the ground stress is at a medium level,forming a tectonic stress field dominated by horizontal stress.The orientation of roadway group’s developing direction is favorable to the extension of in-situ stress direction,and the magnitude and direction of in-situ stress have little influence on the stability of roadway surrounding rock.Roadway roof is composed of sandy mudstone and thin coal line,which is a composite roof with variable thickness.The strength of coal and rock mass fluctuates greatly and is unstable due to the development of cracks.It is very important to control the caving of the composite coal and rock roof in the shallow part of roadway.Based on the distribution law of stress field of roadway group and the evaluation conclusion of geomechanics of surrounding rock,the prestressed rockbolt and anchor cable support technology is adopted in belt roadway,and the detailed scheme and supporting parameters are put forward,the field test has achieved good results,with the maximum displacement of 87 mm for the roof and floor and 81 mm for the two sides,which provides beneficial guidance for the excavation and support of the coal mine roadway group.