灰岩地区危岩类砌体结构破坏解体机制研究

发布时间：2018-01-22 12:41

本文关键词： 灰岩地区危岩类砌体结构解体机制有限元断裂力学模型试验　出处：《重庆交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：灰岩地区危岩“类砌体结构”特征导致危岩体破坏时呈现与砂岩地区危岩破坏不同现象,灰岩地区危岩体破坏后解体现象十分显著,所形成的崩塌灾害具有群发性。因此,开展灰岩地区危岩类砌体结构破坏解体机制研究对于科学认识三峡灰岩地区崩塌灾害形成机制具有重要意义。本文以重庆市巫山县望霞危岩为实际工程背景,采用有限元数值模拟方法、材料力学、断裂力学理论结合室内小尺度模型试验研究灰岩地区危岩类砌体结构破坏解体机制。主要研究成果如下:(1)针对灰岩地区危岩,采用实地踏勘及野外地质调查的形式,构建了适合于分析灰岩地区危岩类砌体结构破坏机制的地质模型。定义了危岩高台比(H/B)的概念,将危岩高台比H/B1时的危岩破坏解体类型定义为“类砌体结构顶部拉剪解体机制”;将危岩高台比H/B1时的危岩破坏解体类型定义为“类砌体结构底部拉剪解体机制”。(2)针对“类砌体结构顶部拉剪解体机制”,采用有限元数值模拟方法,分析获得了顶部拉剪解体型危岩体内部拉剪区域随危岩悬高比c/H、高宽比H/b及危岩体倾角θ的变化规律。在类砌体型危岩砌块交界处定义初始裂纹,引入断裂力学边裂纹拉剪破坏模型,据此采用断裂力学经典解答,分析了类砌体结构顶部拉剪解体机制,获得了不同悬高比c/H、高宽比H/b及危岩体倾角θ的危岩解体判据;以重庆市巫山县望霞危岩区内W1危岩体为例,预测了该危岩体开裂区分布图。同时针对“类砌体结构底部拉剪解体机制”,采用类似方法获得了不同高宽比H/b及危岩体倾角θ的危岩解体判据。以重庆市巫山县望霞危岩区内W2危岩体为例,预测了该危岩体开裂区分布图。(3)将类砌体型危岩视为一能量体系,建立系统能量方程,推导危岩体座滑过程中能量释放量,同时构建了与此过程对应的危岩体突发性解体判据。以望霞W2危岩为例,预测该危岩体座滑偏转到倾角34°时即可能发生突发性解体现象。(4)实施了三个高度530mm、795mm和1060mm,三个宽度230mm、345mm和460mm,三个倾角80°、70°和60°,以及三种粘结方式无粘结、粘土粘结和M5砂浆粘结共计81组试验工况的81个模型倾倒过程解体试验,发现类砌体型危岩高宽比越大,发生倾倒时初始开裂位置的相对高度越小;类砌体型危岩倾角越大,发生倾倒时初始开裂位置的相对高度越高;粘结方式对类砌体型危岩初始开裂位置无影响,但粘结方式能决定危岩体在倾倒过程中是否开裂,以及开裂范围大小,无粘结情况下,开裂的可能性大且发生开裂时分布范围也较有粘结情况广。
[Abstract]:The characteristics of "masonry structure" of dangerous rock in limestone area lead to a different phenomenon when dangerous rock mass is destroyed than that in sandstone area, and the phenomenon of breakup after destruction of dangerous rock mass in limestone area is very significant. The avalanche formed by the disaster has mass occurrence. It is of great significance to study the mechanism of destruction and disintegration of dangerous rock masonry structure in limestone area for the scientific understanding of the formation mechanism of collapse disaster in the three Gorges limestone area. This paper takes Wangxia dangerous rock in Wushan County of Chongqing as the actual engineering background. The finite element numerical simulation method is used to simulate the mechanics of materials. The failure and disintegration mechanism of dangerous rock masonry structure in limestone area is studied by the theory of fracture mechanics combined with laboratory small-scale model test. The main research results are as follows: 1) aiming at dangerous rock in limestone area. In this paper, a geological model suitable for analyzing the failure mechanism of dangerous rock masonry structure in limestone area is constructed by means of field exploration and field geological survey, and the concept of dangerous rock platform ratio H / B is defined. The break-up type of dangerous rock is defined as "tensile and shear collapse mechanism at the top of masonry structure" when the height of dangerous rock is higher than that of H / B1. The break-up type of dangerous rock is defined as "tensile and shear collapse mechanism at the bottom of masonry structure" when the height of dangerous rock is higher than that of H / B1, and the "top tensile and shear disintegration mechanism of similar masonry structure" is defined as "tensile and shear disintegration mechanism at the top of similar masonry structure". The finite element numerical simulation method is used to analyze and obtain the ratio c / h of the tensile shear region with the hanging height of the dangerous rock in the top tension shear break-up type dangerous rock. The variation law of aspect ratio H / b and slope angle 胃 of dangerous rock mass. The initial crack is defined at the junction of the similar masonry dangerous rock block, and the fracture mechanics edge crack tensile and shear failure model is introduced, according to which the classical solution of fracture mechanics is adopted. In this paper, the mechanism of tensile and shear breakup at the top of masonry structure is analyzed, and the criteria of break-up of dangerous rock with different ratio of hanging height c / H, ratio of height to width H / b and slope angle 胃 of dangerous rock mass are obtained. Taking the W1 dangerous rock mass in Wangxia perilous rock area of Wushan County as an example, the distribution map of the cracking area of the dangerous rock mass is predicted. At the same time, the "tensile and shear disintegration mechanism at the bottom of the similar masonry structure" is also discussed. By using the similar method, the criterion of dangerous rock disintegration with different aspect ratio H / b and dangerous rock mass inclination 胃 is obtained. Taking W2 dangerous rock mass in Wangxia perilous rock area, Wushan County, Chongqing as an example. The fracture zone distribution map of the dangerous rock mass is predicted. (3) taking the type of masonry dangerous rock as an energy system, the energy equation of the system is established, and the amount of energy released during the sliding process of the dangerous rock mass is deduced. At the same time, the criterion of sudden disintegration of dangerous rock mass corresponding to this process is constructed, taking Wangxia W2 dangerous rock as an example. It is predicted that the sudden disintegration may occur when the slide of the dangerous rock body deflects to the inclination angle of 34 掳.) three heights of 530mm / 795mm and 1060mm and three widths of 230mm are carried out. 345mm and 460mm, with three inclination angles of 80 掳, 70 掳and 60 掳, and the three kinds of bonding methods without bond. The collapse tests of 81 models under 81 test conditions of clay bond and M5 mortar bond show that the larger the ratio of height to width of dangerous rock of masonry type is, the smaller the relative height of initial cracking position is at the time of dumping. The higher the inclined angle of the similar masonry dangerous rock is, the higher the relative height of the initial cracking position is when the collapse occurs. The bonding mode has no effect on the initial cracking position of the type of masonry dangerous rock, but the bond mode can determine whether the dangerous rock mass cracks during the dumping process, and the extent of the crack, without the case of bond. The possibility of cracking is high and the distribution range of cracking is wider than that of bond.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU364;TU312.3

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