深井巷道围岩再造承载层控制机理研究

Stability of surrounding rock around roadway is related to its state closely. Basic cause of surrounding rock instability is instability of surrounding rock crushed zone in roadway. There is larger surrounding rock crushed zone in deep roadway, control scope of basic support system is limited, and bearing performance of crushed rock mass beyond control scope is worse. There are various support forms on surrounding rock coexist in deep gateway, but it is difficult to control surrounding rock around roadway effectively. Based on the characteristics of layer rock mass in roadway, a renewable bearing stratum is formed in two-side crushed surrounding rock, which is connected into stable stratum in two-side depth. Renewable bearing stratum and basic support system work together, force on basic support system is transferred partially, bear on roadway surface reduces, so surrounding rock stability is guaranteed. The project studies mainly the relationships between surrounding rock stability and all strata in layer rock mass, the relationship between surrounding rock stability and strength, location, thickness of renewable bearing stratum, changing regular of surrounding rock stress and displacement after forming renewable bearing stratum, its realize approach, and couple relationship between renewable bearing stratum and basic support system in roadway. Research results will be theoretical basis on surrounding rock control, and provide effective approach to solve the support problems in deep roadway.

巷道围岩稳定与围岩状态密切相关，围岩失稳的根本原因在于巷道围岩破碎区岩石的失稳。深井巷道围岩存在较大的破碎区，巷道基本支护系统的作用范围有限，作用范围以外的破碎岩体承载性能较差。深井巷道围岩控制尽管多种支护形式并存，但难于实现对巷道围岩的有效控制。课题研究基于巷道围岩层状岩体特征，在巷道两帮破碎围岩内人为形成一承载层，并和两帮深部稳定岩层相连，承载层与巷道基本支护系统共同承载，部分转移巷道基本支护系统的受力，减小巷道支护系统的载荷，从而保证巷道围岩稳定。课题主要研究层状岩体条件下巷道围岩稳定与各岩层之间的关系；巷道围岩稳定与再造承载层强度、层位、厚度之间的关系；巷道围岩再造承载层形成后巷道四周应力场、位移场的变化规律；再造承载层的实现方法以及承载层与巷道基本支护系统之间的耦合关系。研究成果将为深井巷道围岩控制提供理论基础，并将为解决深部巷道的支护问题提供有效的途径。

随着开采深度的增加，巷道围岩变形增大，控制难度加剧，如何有效控制巷道围岩变形已成为实现矿井高产高效开采的关键问题之一。.针对深井大变形巷道，提出了再造承载层支护理念，即通过改善巷道周边一定范围内岩层的力学性能来产生利于巷道稳定的大环境，再辅以基本支护改善其小环境以达到控制巷道围岩变形的目的。运用理论分析、相似材料模拟试验与数值模拟等手段，对再造承载层的合理参数、控制机理、实现方法进行研究。.对一系列承载复合体进行了单轴压缩实验，得到了承载层各因素与承载复合体强度之间的关系，其中，当承载层厚度占承载复合体厚度的60%~70%以上时，承载复合体强度趋向于承载层的强度。运用莫尔强度理论以及能量转换角度解释承载复合体的强度规律。将单轴压缩试验结果与弹塑性力学相结合，分析再造承载层巷道围岩的塑性区及表面位移，得到承载层的合理长度应与塑性区半径相同，承载层的厚度在条件允许的情况下应尽可能的增大。通过正交数值模拟试验，分析巷道塑性区体积及表面位移对承载层因素的敏感度。当承载层在两帮时，分析两帮垂直应力得出：随着承载厚度的增加，帮部浅部应力提高，深部应力降低，两帮的受力均匀化；随着承载层长度增加，峰值应力不断减小，峰值位置向深部转移。承载层厚度合理值为巷道高度的3/4，合理长度应与原岩巷道的帮部塑性区长度相近。提出了承载层的实现方法即两帮安设钢管并注浆，其中形成的钢管混凝土桩同时具有梁与锚杆的作用。巷道两帮再造承载层的相似材料试验及现场应用表明：再造承载层支护巷道后，顶板与两帮的破坏范围可以有效减少，但不能减缓底臌现象，采用再造承载层与基本支护联合支护后，可以全面减小巷道围岩的破坏范围。.巷道两帮再造承载层通过提高帮部承载力，使其所受垂直应力均匀化，能够减小巷道围岩位移及塑性区分布，是对深井巷道围岩控制的一种新尝试。