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深部大断面巷道交叉点围岩稳定性分析及控制技术

Stability analysis and control technology of surrounding rocks at deep large cross-section roadway

  • 摘要: 针对邢东矿-760 m水平大断面巷道交叉点顶板明显下沉、两帮剧烈收敛、底板强烈鼓起、柱墙岩体破碎松散等巷道变形破坏特征,采用理论分析、数值模拟、工程类比及现场观测等方法,针对性地提出了集多层次交错密集高强度锚杆(索)支护技术、多层混凝土喷层拱支护、壁后注浆加固拱和柱墙浇注混凝土加固于一体的锚喷网注联合支护技术,剖析了深部大断面交叉点具体支护方法的围岩控制机理。
    研究表明:①当锚杆安装越密集时,压应力叠加所形成承压拱的最小厚度越大,压力拱承载能力越强;②锚杆间距大于700 mm时,喷层结构最大承载力小于0.55 MPa,随着锚杆间距减小至 400 mm,喷层承载能力与锚杆间距呈类幂函数增长关系;③喷层结构承载能力与喷层厚度呈类线性关系,即喷层承载能力随喷层厚度增大而线性增大;④数值模拟结果表明围岩塑性破坏深度较大的区域位于顶部两肩窝处,且交叉点大部分塑性区深度小于2.4 m,锚杆长度确定为2.4 m时,能够使得锚杆锚固在岩体的弹性区内。
    基于以上研究,结合现场地质生产条件确定巷道交叉点围岩支护方案,并进行现场工程应用。工程实践表明,采用锚喷网注联合控制技术后,顶底板、两帮移近量最大分别为166、134 mm,移近速率最大分别为9.8、7.3 mm/d,巷道围岩总体收敛情况较好,有效控制了-760 m水平大断面巷道交叉点围岩变形。

     

    Abstract: In view of the deformation and damage characteristics of the -760 m level large cross-section roadway in Xingdong Coal Mine, such as obvious subsidence of roof, sharp convergence of two sides, strong heave of floor, broken and loose of pillar wall of rock mass, the combined control technology of bolt-shotcrete-net-grouting, which integrates high strength anchor bolts (cables) support technology with multi-level interleaving, multi-layer concrete spray layer arch support, reinforcement arch with grouting behind segment and reinforcement by pouring concrete into the column wall, is put forward in this paper by methods of theoretical analysis, numerical simulation, engineering analogy and on-site observation. The combined support technology of bolting shotcrete and net injection analyzes the surrounding rock control mechanism of the specific support method of the deep large cross section intersection. The results shows that: ①when the boltsare installed more densely, the minimum thickness of the pressure arch formed by the superposition of compressive stress is greater, and the bearing capacity of the pressure arch is stronger;②when the bolt spacing is more than 700 mm, the maximum bearing capacity of the spray layer structure is less than 0.55 MPa. As the bolt spacing decreases to 400 mm, the bearing capacity of the sprayed layer increases and the spacing of the bolt show apower-like function growth relationship; ③the bearing capacity of the sprayed layer structure and the thickness of the shotcrete layer show a kind of “linear” relationship, that is, the bearing capacity of the spray layer structure has a linear relationship with the thickness of the sprayed layer; ④the numerical simulation results show that the area with the greater plastic failure depth of the surrounding rock is located at the top two shoulder sockets, and most of the plastic zone depth of the intersection is less than 2.4 m. When the length of the bolt is determined to be 2.4 m, the bolt can be anchored in the elastic zone of the rock mass. Based on the above research, combined with the on-site geological production conditions, the surrounding rock support scheme of the roadway intersection is determined, and the field engineering application is carried out. The field engineering practice shows that after the joint control technology of bolting shotcrete and net injection is applied,the maximum approaching distance between the top and bottom plates and the two sides are 166 and 134 mm respectively, and the maximum approaching rates are 9.8 and 7.3 mm/d respectively. The convergen cecondition of surrounding rock in roadway is good. The deformation of the surrounding rock at the intersection of the - 760 m level large section roadway is effectively controlled.

     

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