深部软岩巷道让压壳损伤演化及其支护机理研究

The maintenance difficulty degree of deep soft rock roadway is related to many factors, such as the building parameters of yielding shell, the intensity decay damage evolution of yielding shell during its moving process, the partial destruction compensation support strength and timing of yielding shell, the soft medium filling layer thickness of reservation yield space and the support intensity and opportunity.Reasonable determination of soft medium filling layer thickness of yield space, controlling the extent of moving and unloading of yielding shell, timely carrying out compensation support, erecting secondary support steel frame is the key to solve deep soft rock roadway problems using the pressure shell.To this end, the following research content were mainly carried out in the project:(1) Studied on rheological properties of surrounding rock in deep soft rock roadway and revealed the evolution characteristics of the stress field and the deformation and failure mechanism of deep soft rock roadway.(2) Established the mechanical model and numerical calculation model of full-length anchoring prestressed bolting support, revealed the support mechanism of short-fine-dense bolt, provided the basis for building parameters of the yielding shell.(3) Established intensity damage model of yielding shell moving and unloading,revealed the constitutive relations of yielding shell moving and unloading and the intensity decay damage changes. Studied on the mechanism of yield space buffer and compensation support, determined building parameters of the yielding shell, the reservation yield space and soft medium filling layer thickness and the secondary support intensity and opportunity, provided the basis for support technology of yielding shell- steel frame in deep soft rock roadway.

深部软岩巷道维护难易与让压壳构筑参数、让压壳移动过程其强度衰减损伤演化、让压壳局部破坏补偿支护强度与时机、预留让压空间软介质充填层厚度、支护强度与时机等因素相关，合理确定让压空间以及软介质充填层厚度、控制让压壳移动卸荷程度、及时补偿支护，架设二次支护钢架是应用让压壳解决深部软岩巷道支护难题的关键。为此，本课题主要开展以下研究内容：（1）研究深部软岩巷道围岩流变特性，揭示深部软岩巷道围岩应力场演化特征与变形破坏机理。（2）建立全长锚固预应力锚杆支护作用力学模型与数值计算模型，揭示短细密锚杆支护作用机理，为确定让压壳构筑参数提供依据。（3）建立让压壳移动卸荷强度损伤模型，揭示让压壳移动卸荷本构关系及其强度衰减与损伤演化规律，研究让压空间缓冲与补偿支护机理，确定让压壳构筑参数、预留让压空间及软介质充填层厚度、以及二次支护强度与时机，为研究深部软岩巷道让压壳-钢架耦合支护技术提供依据。

深部巷道围岩控制问题一直困扰着我国煤矿安全高效生产，是亟待解决的科学技术问题之一。让压壳支护技术是控制该类巷道围岩大变形的有效方法之一，但其缺乏完整的理论体系。项目采用实验室试验、理论分析、数值模拟及现场实测等方法，系统研究了深部巷道让压壳损伤演化及其支护机理，取得了以下研究成果：.（1）进行了深部巷道围岩结构特征测试，以及煤岩力学参数测试分析，考虑不同断面形状、不同侧压条件，通过现场实测与数值计算，研究了深部巷道围岩应力与变形规律，分析并得到了深部巷道围岩应力场演化与变形破坏规律。.（2）进行了泥质粉砂岩三轴蠕变试验，建立了泥质粉砂岩蠕变全过程的粘弹塑性蠕变模型，并推导出该蠕变模型的本构方程；采用FLAC3D软件，分析并得到了深部巷道流变规律以及塑性区分布规律。.（3）建立了全长锚固预应力锚杆支护力学模型，推导出锚杆轴应力和剪应力计算式；推导出围岩沿锚杆轴向、径向和环向的应力计算式，分析并得到了预紧力、锚杆长度、直径与锚杆轴应力和剪应力的关系；分析并得到了锚杆长度与预紧力对围岩应力的影响规律。.（4）建立软岩巷道让压壳支护围岩力学模型，推导出让压壳支护围岩释放能量计算公式，分析并揭示了让压壳移动卸荷本构关系及其强度衰减规律，得到了让压壳支护强度与二次支架补偿支护强度的关系，给出了让压壳厚度与支护强度及时机的确定方法。.（5）分析了深部巷道预留让压空间缓冲作用原理，采用Bonaitin-Thomson模型对巷道围岩进行了力学分析，推导出预留让压空间的计算式，给出了预留让压空间的确定方法，分析并确定了二次补偿支护强度与时机，揭示了预留让压空间缓冲与补偿支护机理。.（6）结合曲江矿-850m东皮带大巷工程地质条件，展开了现场工业性试验。应用结果表明，采用让压壳-钢支架耦合支护技术后，让压壳与外部钢架协调支护效果良好，较好地控制了深部巷道围岩有害变形，该技术方案简单易行，可在类似条件下的深部巷道围岩控制领域推广应用。