错层位巷道围岩稳定性及控制机理研究

Because stagger arrangement roadway were located in stress adjustment zone in thick coal seam, stability of surrounding rock would change. The project will combine of research methods on field measurement, test researching, numerical simulation and theoretic analysis. Aiming at stagger arrangement roadway, evolution law of surrounding rock structure will be studied. Using triaxial equipment, tensile creep rupture degree and compression creep density of coal or rock sample with time variation will be tested. Three-dimensional rheologic mechanical model and constitutive equation of rock deformation-cracking for stagger arrangement roadway will be established. Three-dimensional rheologic mathematical model of rock deformation-cracking for stagger arrangement roadway will be established, and solved by finite difference method of FLAC3D redevelopment with visual C++ and FISH. Variation rule of Stress field,displacement field and fracture field will be simulated in different excavation and mining stage. Evolution process of surrounding rock failure will be simulated.Stress and displacemeng characteristics of different support method will be analyzed. Evolution rule of rock deformation failure will be derived.Method of surrounding rock control will be optimized. Through field application, applicable condition and optimization scheme of stagger arrangement roadway will be put forward. Stagger arrangement roadway not only reduce mining loss of thick coal seam, improve mechanical environment of roadway surrounding rock, but also decrease support difficulty of mining roadway. It has obvious advantages and promising prospect.

错层位巷道处于应力调整区，巷道围岩稳定性发生变化。项目采用现场监测、实验研究、数值模拟及理论分析相结合的研究方法，研究错层位巷道围岩结构演化规律；利用三轴设备，实测煤/岩样试件拉张蠕变破裂度、压缩蠕变密实度等参数随时间的变化规律，建立错层位巷道围岩变形破裂三维流变力学模型及本构方程；建立错层位巷道围岩变形破裂三维流变数学模型，通过VC++与FISH编程对FLAC3D进行二次开发，编制有限元计算程序，模拟错层位巷道开挖不同阶段及开采扰动的围岩应力场-位移场-裂隙场空间演化规律，分析错层位巷道不同支护方式下的围岩应力/位移特征，得到围岩变形破坏演化规律，优化错层位巷道围岩控制方式。通过现场应用，提出错层位巷道布置的适用条件及优化方案。错层位巷道对减少厚煤层开采资源浪费、改善巷道围岩力学环境、降低回采巷道支护难度具有明显优势和推广应用前景。

本项目研究了错层位沿空巷道特殊的围岩卸让压结构能够解决常规沿空掘巷在深部开采、坚硬顶板时存在巷道维护困难的问题。对比分析了留煤柱护巷和沿空留（掘）巷围岩结构特征，阐述了影响沿空巷道围岩稳定性的主控因素-侧向基本顶关键块的运移。通过力学分析和实验室实验，研究了错层位巷道侧向基本顶下方卸让压围岩结构体系卸让压的力学机理。研究表明：错层位布置使巷道远离侧向集中应力，侧向支承压力向煤体深部转移的效果，避免了沿空巷道受深部高地应力的影响，实现了自动卸压的效果；矸石-三角煤柱结构通过松散矸石大变形缓冲顶板显著运动动载，通过高承载限侧矸石、高稳定性三角煤柱承担关键块静载；自由空间-碎胀矸石组合结构坚硬顶板充分回转、降至低位态，实现结构性让压，避免顶板受侧向关键块剧烈运动的影响。研制了大尺寸破碎岩石承压变形试验系统，选取某矿区典型顶板砂岩，考虑冒落区破碎岩石粒径的分布特征和受力状态，进行了正态分布的粒径级配和梯形分级加载试验。试验表明：随轴向载荷增加，破碎岩石轴向变形逐渐增大，残余碎胀系数和空隙率逐渐减小，加载较恒载阶段尤为明显；恒载初期，轴向应变增长较快，而后逐渐变缓并趋于平稳，应变时间历程呈现对数关系；加载阶段，随载荷增大，破碎岩石试样轴向应变差值呈现先减小后增大，恒载阶段，随载荷增大，破碎岩石试样轴向应变差值则呈现先增大后减小；破碎岩石承压后的变形分为瞬时压缩变形和长期压缩变形两个阶段，主要由颗粒位置调整、原始或新生小颗粒滑动填充空隙引起的；破碎砂岩试样以粒径15～20mm为承压变形过程中的稳定粒径，试验后，粒径＜15mm的含量均有增加，粒径＞20mm的含量则均有减小，为破碎砂岩试样总质量的16.76%。研究结果对采空区覆岩移动变形预测及控制具有一定的指导意义。