巨厚煤层三软回采巷道恒阻让压互补支护研究

RESEARCH ON COMPLEMENTARY SUPPORTING SYSTEM OF CONSTANT RESISTANCE WITH LOAD RELEASE FOR THREE-SOFT MINING ROADWAYS IN EXTREMELY THICK COAL SEAM

针对沈阳清水煤矿第三系巨厚大地压软围岩煤层回采巷道开掘后支护失效严重、围岩大变形及4次返修无法稳定的现象,分析围岩塑性流变、非对称变形破坏、支护体与围岩大变形不协调等变形力学机制。提出采用恒阻大变形锚杆初次支护,在恒阻力作用下保护锚固体的承载力,通过恒阻锚杆的延伸多次释放变形能,将集中应力转移到深部,调动深部围岩承载能力,形成稳定的塑性承载圈;然后针对回采巷道变形特点采用顶板加强、两帮让压、底角加固的二次互补加强支护,形成适应三软巷道变形特征的围岩–支护协同承载体,将围岩变形速率控制在合理范围。基于该方法下提出的锚索+恒阻大变形锚杆+钢带+底角锚注联合支护设计,在该矿南二采区205工作面运输顺槽中使用后,顶板下沉降低75%,两帮收缩减小60%,底臌减小42%,巷道支护状况得到明显改善。实践证明,恒阻让压互补支护系统可有效控制三软巷道围岩稳定。

The surrounding rock of roadway in Tertiary thick coal seam in Qingshui coal mine of Shenyang is soft with high ground pressure.The tunnel had large deformation with 4 times reinforcement and much damaged support after excavation.The mechanisms of rock plastic flow,asymmetry deformation and failure and inharmonic deformation between support and rock are analyzed.The initial support with constant resistance and large deformation bolt can protect the support capacity of the anchorage zone.After the release of deformation energy by the extensional deformation of the constant resistance and large deformation bolt,the concentration stress is transferred to deep to utilize the strength of deep surrounding rock;then the stable loading plastic zone is formed.According to the characteristic of the mining roadway,the reinforced support is complementary with the strengthened roof,released stress sidewalls and supported side corner.The stability is dependent on the common load by support and surrounding rock.The new design containing anchor cable,constant resistance and large deformation bolt,steel band,injected pile is applied to successfully controlling the roadway at #205 working face in second mining area in southern mine.The theory is applied to controlling the stability of this kind of coal entry.The roof subsidence,sidewall shrinkage and floor heave reduced by 75%,60%,42%,respectively.The practice shows that the proposed method can control the deformation of the roadway with soft rock.