赤水市元厚镇危岩带变形破坏机制及稳定性分析

发布时间：2018-02-09 22:30

本文关键词： 危岩变形破坏机制稳定性评价断裂力学离散元贵州赤水　出处：《贵州大学》2015年硕士论文　论文类型：学位论文

【摘要】：崩塌是贵州省易发的地质灾害之一。贵州省赤水市元厚镇红层危岩带位于元厚镇北部陡崖地带,大小危岩体(崩塌体)共计49个,威胁着镇集内居民的人身及财产安全。本论文在了解国内外研究现状、收集前人研究资料和现场详细勘查的基础上,强调了危岩体的地质原型现场调研与地质过程分析,借助离散元程序UDEC对危岩体的变形破坏过程进行模拟。研究危岩带变形破坏特征、成因机制及破坏模式。采用极限平衡理论和断裂力学两种分析法进行了研究区内危岩体的稳定性评价。主要获得的认识及成果如下:1、研究区危岩带所处红层岩层斜坡,总体呈上陡下缓的地貌特征,从山顶到坡脚表现为三个台阶。斜坡坡角75~85°,地层为侏罗系上统蓬莱镇组(J3p)的泥岩和砂岩互层组合,岩层倾角较小(15°)。高陡的地貌特征为斜坡的变形提供了较好的临空条件。研究区内发育3组优势裂隙,将岩体切割成块状并形成明显的外倾结构面,加剧了岩体的破碎程度,为危岩体的形成及崩塌创造了有利的条件。2、总结了研究区危岩带特征及规律。危岩带发育在层状岩体斜坡上塑造成峻峭的陡崖地貌,而这种陡峻地貌形态又能加剧危岩带发育过程,其结果是使悬崖后退,高度降低,坡地逐渐变缓,危岩的崩塌作用也渐趋消亡。3、划分了危岩带变形破坏阶段。元厚镇危岩带是在不利坡体组合和地质结构,加之气候条件综合作用下形成的,其演化过程分为6个阶段:初始阶段(阶段1);河谷下切阶段(阶段2);差异风化阶段(阶段3);危岩体形成阶段(阶段4);危岩体变形破坏阶段(阶段5);崩塌完成阶段(阶段6)。4、根据崩塌体结构特征、变形特征、受力状况和失稳方式的不同,将研究区危岩体破坏模式分为倾倒式和坠落式两类,并初步分析了每一种破坏模式的成因机制。5、建立UDEC离散元数值模拟模型,模拟在自然和降雨作用下,危岩体的变形破坏演变情况。结果显示差异风化是危岩带形成的根本原因,降雨是危岩带变形加剧和崩塌的诱发因素。危岩带变形破坏机制是:由于差异分化形成初始岩腔及卸荷裂隙,改变坡体应力状态,使其稳定性下降,在降雨等其他外界因素下,危岩体崩落。6、采用极限平衡法和断裂力学法评价结果得出:分别对研究区危岩体在三种情况(天然、暴雨、暴雨+地震)下进行稳定性计算,元厚镇危岩带目前大部分危岩体处于第四阶段成熟期(危岩体形成阶段)和第五阶段(危岩体变形破坏阶段)的孕育期,处于欠稳定状态,建议采取清除+嵌补支撑+锚固+SNS主动防护网的综合治理方案。
[Abstract]:Collapse is one of the geological hazards easily occurring in Guizhou Province. The Red Strata dangerous Rock Belt of Yuanhou Town, Chishui City, Guizhou Province, is located in the steep cliff zone north of Yuanhou Town, with a total of 49 dangerous rock masses (collapses). This paper, on the basis of understanding the present research situation at home and abroad, collecting the previous research data and site detailed exploration, emphasizes the site investigation and geological process analysis of the geological prototype of the dangerous rock mass. The process of deformation and failure of dangerous rock mass is simulated by means of discrete element program UDEC. The characteristics of deformation and failure of dangerous rock zone are studied. Genetic mechanism and failure mode. The stability evaluation of dangerous rock mass in the study area is carried out by using limit equilibrium theory and two kinds of analysis methods of fracture mechanics. The main knowledge and results obtained are as follows: 1. The red bed rock layer slope located in the dangerous rock belt in the study area is studied. There are three steps from the top of the hill to the foot of the slope. The slope angle is 75 ~ 85 掳, and the formation is the mudstone and sandstone interbedded assemblage of the Jurassic Upper Penglai Zhen formation (J _ 3p). The slope angle is smaller than 15 掳, and the high and steep geomorphology features provide better conditions for slope deformation. Three groups of dominant fractures are developed in the study area, which cut the rock mass into blocks and form obvious extroverted structural planes, thus exacerbating the degree of rock mass fragmentation. This paper creates favorable conditions for the formation and collapse of dangerous rock mass, summarizes the characteristics and laws of dangerous rock zone in the study area. The dangerous rock zone is formed on the slope of layered rock mass into a steep cliff geomorphology. However, the steep geomorphology can aggravate the development process of the dangerous rock belt. As a result, the cliff recedes, the height decreases, and the slope gradually slows down. The collapse of dangerous rock is also gradually dying out, which divides the deformation-failure stage of dangerous rock zone into three stages. The dangerous rock belt in Yuanhuzhen is formed under the combination of unfavorable slope body assemblage and geological structure, as well as the comprehensive action of climatic conditions. The evolution process is divided into six stages: initial stage (stage 1), valley shearing stage (stage 2), differential weathering stage (stage 3), dangerous rock mass formation stage (stage 4), critical rock mass deformation stage (stage 5) and collapse stage (stage 5). (stage 6. 4, according to the structural characteristics of the collapse, According to the difference of deformation characteristics, stress condition and instability mode, the failure modes of dangerous rock mass in the study area are divided into two types: toppling type and falling type, and the cause mechanism of each failure mode is analyzed preliminarily, and the numerical simulation model of UDEC discrete element is established. Under the action of nature and rainfall, the deformation and failure evolution of dangerous rock mass is simulated. The results show that differential weathering is the fundamental reason for the formation of dangerous rock zone. Rainfall is the inducing factor of the deformation and collapse of the dangerous rock zone. The mechanism of deformation and failure of the dangerous rock belt is that the initial rock cavities and unloading cracks are formed due to the differential differentiation, the stress state of slope body is changed and the stability of slope body is decreased, and other external factors such as rainfall, etc. Using limit equilibrium method and fracture mechanics method to evaluate the stability of dangerous rock mass under three conditions (natural, rainstorm, rainstorm earthquake) in the study area. At present, most of the dangerous rock masses in Yuanhuzhen dangerous rock belt are in the gestation period of maturity stage (formation stage of dangerous rock mass) and stage 5th (deformation and failure stage of dangerous rock mass) in 4th stage, and are in an unstable state. It is suggested that the comprehensive treatment scheme of SNS active protection net should be adopted.
【学位授予单位】：贵州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P642.2

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