【作者】 李建新；

【导师】 王来贵；

【作者基本信息】 辽宁工程技术大学 ， 工程力学， 2014， 博士

【摘要】 随着中国经济快速发展,交通基础设施建设越来越多,许多地方修建铁路、高速公路等都不可避免地要穿过采空区,而采空区所处地基不可避让,或采取避让方案占用良田和费用比较高时,采空区顶板稳定性问题作为铁路建设的不良地质问题已越来越突出,分析动力荷载对采空区变形破坏的影响,为采空区稳定性评估和工程治理设计提供可靠的依据,对保证铁路在设计使用年限内安全营运有着重要的意义。综合应用相似材料模拟实验、理论分析、数值模拟等方法,重点就水及地表列车动荷载对浅伏采空区变形破坏影响做了比较深入地研究,主要成果如下：(1)通过相似材料模拟实验,观测浅埋煤层开采后采空区上覆岩层变形破坏演化过程和最终处于相对稳定的状态特征,最终采空区上覆岩层基本上分“两带”即垮落带和断裂带,为消除垮落带内岩块重新“活化”的隐患,提出半充填注浆处理采空区的方法,并通过浆液配比实验测定其强度,结合浆体胶结后的结构特征,建立了混凝土桩柱体和冒落矸石胶结体的力学模型,分析了其破坏方式,并推导出其破坏失稳的力学条件。(2)通过岩体试件力学特性的试验研究,结果表明：岩石的抗压强度与抗剪强度随含水量的增加而降低,但对不同类型的岩石影响程度不一样,对坚硬岩石强度影响较小,而对软弱岩石影响较大,并引用混凝土弹性模量与抗压强度之间的关系式,结合实验结果,推导出弹性模量与含水量之间的关系。(3)将采空区上覆顶板岩层和桩柱体看成一个系统建立力学模型,从整体上对其进行分析研究。根据岩体物理参数与水的函数关系式,推导出采空区系统在水作用下的总势能函数,利用尖点突变理论导出系统突变失稳的充要力学条件,分析了水作用下浅伏采空区破坏失稳机理。(4)针对浅埋煤层采空区易受水及地表动力荷载的影响,建立列车-轨道-路基系统耦合动力学模型。利用ANSYS对浅伏采空区上覆岩层和运行列车建模,并用瞬态求解器进行动力方程的计算,分析不同跨度和不同含水量条件下列车通过采空区地表各点的最大竖向位移、采空区中部垂直剖面岩层各点竖向位移、采空区围岩应力及应变的影响。更多还原

【Abstract】 With the rapid development of economy, the traffic infrastructure construction is increasing, many local railways, highways are inevitable to go through goaf. Therefore, the effect of dynamic loads on deformation and failure of goaf is researched for providing a reliable basis to stability evaluation and project management, the research has also significant to ensure the safe operation of the railway in the design period. In this paper, laboratory experiments, theoretical analysis and numerical simulation method are adopted, then the effect of water and dynamic train load on deformation and failure of goaf are studied. The main content and results are given in the following:(1) Deformation and failure evolution process of mine strata in shallow coal goaf and characteristics of relatively stable state are observed by simulation experiment of similar material. The final mined strata is basically divided into’two belts", i.e. caving zone and fracture zone. In order to eliminate the "re-activation" of caving zone, semi filling and grouting treatment method for goaf is proposed. The strength of goaf is determined by the slurry mixing experiment, and the failure modes of concrete pile body and the instability conditions of falling rock cemented are analyzed by combining with the structure characteristics of slurry cementing.(2) The test of mechanical properties of rock specimen indicates that the compressive and shear strength of rock is decreased with the increase of water content, but the degree of influence is different for different type rock, actually, little effect on the strength of hard rock, and larger effect on weak rock. The relationship between elastic modulus and water content is deduced by combining with the test and formula of relationship between elastic modulus and compressive strength of concrete. The rock density, damping ratio and damping coefficients are function of water content, and formula of relationship between them and water content can be deduced by linear fitting method for measured values.(3) The roof strata of area mined out and pile body are selected as a system, and the mechanical model is established and analyzed. According to the function of physical parameters of rock and water content, the total potential energy function of the goaf with the action of water is deduced. Then the sufficient mechanics condition of system catastrophe is given by using the cusp catastrophe theory, and the effect of damage failure mechanism and stability is analyzed.(4) The coupling dynamic model of train-pathway-subgrade is established for considering that goaf be affected easily by water and surface train load. The overlying strata of shallow goaf and running train are modeled by ANSYS software, and the dynamic equations are solved by the transient solver. The effect of vertical displacement for surface of goaf is analyzed under the condition of different span and water content, the effect of vertical displacement of strata for the vertical profiles in middle of goaf and the stress and strain of rock surrounding goaf are also analyzed for the same conditions.更多还原