基于能量分析的锚杆与锚索协同支护研究

发布时间：2018-05-15 00:41

本文选题：能量分析 + 应变能密度　；参考：《中国矿业大学》2015年硕士论文

【摘要】：岩石的变形破坏过程始终伴随着能量的转化和转移,地下工程围岩体变形失稳过程中能量的变化也贯穿其中,支护体的施加对围岩体的变形失稳具有一定的抑制作用,对围岩内能量的转化和转移也必定存在影响。因此,分析地下工程围岩体在支护作用下能量的变化特性,可为巷道围岩支护理论和支护设计提供指导。根据最低能量原理,任何体系在处于最低能量状态时是最稳定的。基于此,本文首先采用理论分析的方法,以Mohr-Coulomb屈服准则为依据,从能量角度分析圆形巷道开挖后巷道围岩内塑性应变能和总能量在围岩中的分布情况及其影响参数,以及主要影响参数之间的协同匹配效应;其次,以围岩能量为评判标准,采用数值模拟方法,分析锚杆与锚索支护参数之间的协同匹配效应。本文获得以下主要结论:(1)针对圆形巷道,推导围岩内总能量密度和弹性能密度分布公式,获得围岩总能量密度和弹性能密度的变化和分布规律。(2)通过分析巷道开挖后围岩能量分布特征,发现根据塑性位势理论得到的位移分布式不适用于塑性区,由此位移所求塑性区总能量在部分范围内小于围岩弹性能,违背能量守恒定律。(3)影响围岩弹性能和塑性能的敏感因子是原岩力学参数和原岩应力,其中,粘聚力相比于内摩擦角对破碎区围岩能量影响较大,提高弹性模量可有效减少破碎区围岩内的能量;增强支护力可以增加围岩的弹性能,同时减少破碎区围岩的塑性破坏能及其集聚程度,有利于围岩稳定。(4)增加锚杆预紧力可以增大岩体的粘聚力,粘聚力的增加可以减少破碎区范围,但会加剧塑性能的集聚,需要配以组合锚索为围岩提供均布支护力,减弱围岩塑性能集聚程度;而粘聚力和支护力的增加会提高围岩的弹性能,需要配以高弹性模量的锚杆、锚索,增加整体的弹性模量,减少围岩的弹性能和位移,使巷道围岩处于少破碎、均匀破碎和低能量的稳定状态。(5)锚索预紧力是围岩能量的敏感因子,而锚索长度对围岩能量没有影响,考虑到锚固段附加拉应力场对巷道附近围岩能量的波及,常规条件下锚索长度应在5m~7.5m之间。(6)组合锚索的支护效果优于单体锚索,且锚索预紧力和锚索间距之间存在协同匹配效应,在锚索预紧力较小时需减小锚索间距,而较大的锚索预紧力可适当增加锚索间距。(7)支护的目的不仅仅是控制围岩的变形、提高围岩强度,而是在尽可能减少巷道附近围岩塑性破坏能及其集聚程度的前提下提高破坏后围岩的稳定性。
[Abstract]:The process of rock deformation and failure is always accompanied by the transformation and transfer of energy, and the change of energy in the process of deformation and instability of surrounding rock mass of underground engineering also runs through it, and the application of supporting body can restrain the deformation and instability of surrounding rock body to a certain extent. The transformation and transfer of energy in surrounding rock must also be affected. Therefore, the analysis of the energy variation characteristics of surrounding rock mass in underground engineering under the action of support can provide guidance for the supporting theory and design of roadway surrounding rock. According to the principle of minimum energy, any system is the most stable in the lowest energy state. Based on this, the distribution of plastic strain energy and total energy in surrounding rock of circular roadway after excavation and its influence parameters are analyzed from the angle of energy, based on Mohr-Coulomb yield criterion. Secondly, the synergetic matching effect between anchor and cable support parameters is analyzed by numerical simulation based on the energy of surrounding rock. In this paper, the following main conclusions are obtained: (1) for circular roadway, the distribution formulas of total energy density and elastic energy density in surrounding rock are derived. The variation and distribution of total energy density and elastic energy density of surrounding rock are obtained. (2) by analyzing the energy distribution characteristics of surrounding rock after tunnel excavation, it is found that the displacement distribution obtained from plastic potential theory is not suitable for plastic zone. The total energy of the plastic zone obtained by displacement is smaller than the elastic energy of surrounding rock in some extent, and the sensitive factor affecting the elastic energy and plastic properties of surrounding rock is the mechanical parameter and stress of the original rock, which violates the law of conservation of energy. Compared with the angle of internal friction, the cohesive force has a greater influence on the energy of the surrounding rock in the broken area, and the increase of the elastic modulus can effectively reduce the energy in the surrounding rock of the broken area, and the strengthening of the supporting force can increase the elastic energy of the surrounding rock. At the same time, reducing the plastic failure energy and gathering degree of the surrounding rock in the broken area, which is beneficial to the stability of the surrounding rock, increases the pretightening force of the anchor rod can increase the cohesion of the rock mass, and the increase of the cohesion force can reduce the area of the broken area, but it will aggravate the accumulation of the plastic properties. It is necessary to use combined anchor cables to provide uniform supporting force for surrounding rock, to weaken the accumulation degree of surrounding rock plastic properties, and the increase of cohesion and support force will improve the elastic performance of surrounding rock, and the anchor cable with high elastic modulus is needed. Increasing the elastic modulus of the whole, reducing the elastic energy and displacement of the surrounding rock, making the surrounding rock of the roadway in the condition of less breakage, uniform breakage and stable state of low energy, the pretightening force of the anchor cable is the sensitive factor of the energy of the surrounding rock. However, the length of anchor cable has no effect on the energy of surrounding rock. Considering the effect of additional tensile stress field of anchor section on surrounding rock energy near roadway, the support effect of combined anchor cable should be better than that of single anchor cable under conventional conditions. Moreover, there is a synergistic matching effect between the pre-tightening force of anchor cable and the distance between anchor cables. When the pre-tension force of anchor cable is small, the distance between anchor and cable should be reduced, but the larger pre-tightening force of anchor cable can increase the distance between anchor cable and cable appropriately. The purpose of supporting is not only to control the deformation of surrounding rock, but also to control the deformation of surrounding rock. In order to improve the strength of surrounding rock, the stability of surrounding rock is improved on the premise of reducing the plastic failure energy of surrounding rock near roadway and its accumulation degree as far as possible.
【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

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