钢排桩法控制沿空留巷底鼓研究

发布时间：2018-10-29 22:59

【摘要】：本文在前人研究的基础上,综合运用实验室试验、现场实测、数值计算以及理论分析等方法,从岩石峰后蠕变规律着手,对比分析了沿空留巷服务期间底板变形与受载演化过程,揭示了沿空留巷底鼓各阶段力学成因,确定了针对性的底鼓控制对策,在此基础上,提出一种控制沿空留巷底鼓的新方法——钢排桩法,并对其技术有效性、经济优越性、控制机理和影响因素等方面内容进行了深入研究。主要研究成果为:(1)通过不同损伤程度和围压改变条件下岩石峰后蠕变试验,发现:①岩石峰后损伤程度越小,蠕变速率越小,自稳时间越长;②增加围压可以改善峰后岩石应力状态,进而改善其蠕变性态;③岩石峰后蠕变破坏形式为X状剪切破坏,破坏后块体沿破裂面发生较大滑移。(2)对比整个服务期间沿空留巷底板变形破坏演化过程和上覆基本顶岩层破断运移过程,将沿空留巷底鼓分为四个阶段:一次回采影响缓和阶段、一次回采影响剧烈阶段、留巷稳定阶段、二次回采超前影响阶段。(3)研究得到了沿空留巷底鼓各阶段力学成因。对于一次回采影响缓和阶段、一次回采影响剧烈阶段和二次回采影响阶段,其底鼓力学成因可归结为:①两帮底板在高支承压力作用下相对巷道底板整体下沉;②两帮已破坏底板岩体在高支承压力作用下向巷内临空面滑移;③巷道底板在两帮底板挤压作用下产生向巷内方向的运移;对于留巷稳定阶段,其底鼓力学成因是已破坏底板岩体的蠕变变形与蠕变破坏后块体沿破裂面的滑移。(4)利用数值计算对钢排桩法的技术有效性进行了对比研究,结果表明钢排桩法可以显著控制沿空留巷底鼓,使累计底鼓量、底鼓剧烈程度以及工作面回采动压扰动范围均大幅度减小,且相较于底板锚杆法和卧底法,钢排桩法控制沿空留巷底鼓具有明显的技术、经济优越性。(5)研究得到了钢排桩法控制沿空留巷底鼓机理:①在桩后岩体中形成附加水平应力场和主压应力拱,提高桩后岩体的强度和刚度;②削弱桩后岩体对底板岩体的挤压作用,降低底板岩体的变形破坏程度;③利用底板拉应变压缩区向下的拉力限制拉应变上升区岩体向巷内方向的运移;④降低进入留巷稳定阶段时底板岩体的损伤程度,改善该阶段底板已破坏岩体蠕变性态。(6)对比分析了不同钢桩参数对沿空留巷底鼓控制效果的影响,得到钢桩安装倾角越大、桩体长度越大、安装排距越小,底鼓控制效果越好。
[Abstract]:On the basis of previous studies, this paper uses the methods of laboratory test, field measurement, numerical calculation and theoretical analysis, and proceeds from the creep law of rock after peak. The evolution process of bottom plate deformation and load during the service period of gob-side roadway is compared and analyzed, and the mechanics causes of each stage of bottom drum along goaf are revealed, and the corresponding control countermeasures are determined, on the basis of which, In this paper, a new method of controlling the bottom heave along the gob is put forward, and the technical effectiveness, economic superiority, control mechanism and influencing factors are deeply studied. The main results are as follows: (1) through the post-peak creep test under different damage degree and confining pressure, it is found that: (1) the smaller the post-peak damage degree, the smaller the creep rate and the longer the self-stabilization time; (2) increasing confining pressure can improve the stress state of rock after peak, and then improve the creep behavior of rock; (3) the post-peak creep failure of rock is X-shaped shear failure, and the block slips along the fracture surface after failure. (2) the evolution process of deformation and failure along the bottom plate of goaf roadway during the whole service period and the fracture and migration process of overlying basic top rock are compared. The bottom drum along the gob is divided into four stages: one stage of mining influence mitigation stage, one stage of mining influence intensely, the stage of retaining roadway stabilization stage, and the stage of secondary mining advance stage. (3) the mechanical causes of each stage of roadway bottom drum along goaf are obtained. For the first mining impact mitigation stage, the first mining impact severe stage and the secondary mining impact stage, the mechanical causes of the bottom heave can be summed up as: 1 the two sides of the floor under the action of high supporting pressure relative to the overall subsidence of the roadway floor; (2) the rock mass of the two sides has been damaged and slid to the face of the goaf under the action of high supporting pressure, and 3 the roadway floor has the migration in the direction of the roadway under the action of the extrusion of the two sides of the floor plate; For the stability stage of roadway, the mechanical cause of bottom drum is the creep deformation of damaged floor rock mass and the slippage of the block along the fracture surface after creep failure. (4) the technical effectiveness of the steel column pile method is compared with that of the steel column pile method by numerical calculation. The results show that the steel row pile method can significantly control the bottom drum along the gob and reduce the accumulative floor heave, the intensity of the bottom drum and the disturbance range of the mining pressure of the working face, and compared with the bottom plate anchor method and the underground method, The steel row pile method has obvious technology and economic superiority in controlling the bottom drum along the gob. (5) the mechanism of controlling the bottom drum along the goaf by the steel row pile method is studied: 1 the additional horizontal stress field and the main compressive stress arch are formed in the rock mass behind the pile. Improving the strength and stiffness of the rock mass behind the pile; (2) to weaken the squeezing effect of the post-pile rock mass on the floor rock mass and to reduce the degree of deformation and failure of the floor rock mass, 3 to limit the movement of rock mass in the direction of roadway in the upward zone of tensile strain by using the downward tension force in the tensile strain compression zone of the bottom plate; (4) reducing the damage degree of floor rock mass when entering the stage of roadway stability, and improving the creep behavior of rock mass destroyed in this stage. (6) the effect of different parameters of steel pile on the control effect of bottom heave along goaf retaining roadway is compared and analyzed. The results show that the larger the angle of steel pile installation, the greater the pile length, the smaller the mounting distance, the better the control effect of bottom drum.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD353

【参考文献】