IMHE OpenIR  > 山地灾害与地表过程重点实验室
岩崩灾害形成演化机理研究
Alternative TitleFormation and Evolution Mechamism of Rock avalanche
Language中文
王忠福
Thesis Advisor何思明
2015
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Name博士
Degree Discipline岩土工程
Keyword岩崩灾害 形成机理 动力演化 模型试验 Pfc3d
Abstract我国是一个山地大国,山区面积约占国土陆地面积的2/3,主要集中在西部地区。西部山区地形起伏大,地质环境脆弱、构造复杂、地震频发、岩体破碎、降雨充沛、特殊的地形地貌、地质环境及气候条件使得该区域一直是地质灾害的高发区和多发区。岩崩灾害是西部山区一种常见的地质灾害,具有突发性,可预见性差,速度快,能量高,运动距离远,影响范围大,监测预警困难,危害严重等特点,是山区地质灾害防灾减灾的重点和难点。 据全国290个县市地质灾害的调查结果显示,岩崩灾害在地质灾害中所占的比例高达17%,是除滑坡之外第二大地质灾害类型。在岩崩灾害诱发因素中,降雨、地震、人类工程活动是主要诱发因素。近年来,岩崩灾害频 发并造成重大的人员伤亡和财产损失。由于岩崩灾害研究基础还比较薄弱,减灾防灾能力还难以满足国家经济建设和公共安全的需要。针对岩崩灾害基础研究与减灾实践中存在的难点问题,以岩崩灾害形成演化地质力学模型研究为基础,探索岩崩灾害形成、运动到堆积的动力演化规律,揭示危岩裂隙失稳扩展的力学机理;研究岩崩碎屑流的动力过程与机理;揭示岩崩灾害对承灾体的动力相互作用机理,为潜在岩崩灾害识别、定量风险评估与减灾关键技术研发提供基础。取得的主要研究成果如下: 1.初步揭示了危岩裂隙扩展的宏细观机理 基于细观力学理论方法,利用室内试验及声发射试验分析岩样的细观动态损伤演化过程及其力学特性。结合断裂力学的相关理论对岩体中典型裂隙的开裂、扩展机理进行了分析研究,初步揭示岩崩灾害从微观裂隙形成到宏观破坏演化的机理。 2.揭示了岩崩体性质、规模及坡面坡度对其流动性的定量影响 构建了室内小尺度无侧限岩崩体动力演化过程模型试验系统。研究了崩塌体粒径大小、形状、规模、崩塌次数及坡面坡度等因素对岩崩体流动性与堆积形态参数的影响,并得出以下规律: (1)在相同试验条件下,碎屑颗粒尺寸对滑移距离、等值摩擦系数影响较大,碎屑颗粒尺寸越大,滑移距离越远,岩崩堆积体堆积长度越大,堆积高度越低,堆积宽度越大,等值摩擦系数越小,岩崩碎屑物的流动性越强。 (2)岩崩体积越大,重心运移距离越近,远端位移越大,碎屑物堆积长度越大,等值摩擦系数越大,不同岩崩体积碎屑颗粒的堆积形态相似。 (3)随着分次岩崩次数的增加,碎屑物堆积长度和等值摩擦角均增大,而运移距离随着岩崩次数的增加而有减小趋势; (4)坡度增加,碎屑颗粒堆积长度减小,滑移距离增加,等值摩擦角减小。 (5)在相同颗粒尺寸条件下,不同颗粒形状的碎屑颗粒堆积形态基本相似,堆积宽度相同;卵圆形颗粒的堆积长度要比砾角状颗粒的大,运移距离要比砾石的大,说明颗粒磨圆度越好,碎屑颗粒的流动性越强。 3.发展了不规则形状PFC3D模型,并用于岩崩体动力过程分析 在克服传统颗粒离散元缺点的基础上,以不规则形状岩崩颗粒为基元,建立了以真实岩崩颗粒形状为计算单元的动力过程数值分析模型。研究了微观接触模型参数变化对岩崩碎屑流的堆积形态、堆积宽度、堆积厚度、运移距离、运动速度等参数的影响规律。通过对比发现,基于真实颗粒体形状PFC3D的数值计算的三维动力过程分析模型与模型试验结果有较好的相近性。 4.开展了岩崩灾害与承灾体动力相互作用的PFC3D-FLAC3D耦合研究 构建了岩崩灾害与成灾体相互作用的物理模型试验装置,研究了挡墙不同位置、不同高度对碎屑流堆积形态及速度的影响;采用PFC3D-FLAC3D耦合理论与计算方法研究岩崩灾害与承灾体的动力相互作用。 5.西藏樟木扎美拉山岩崩灾害演化动力过程及危害范围预测 建立了樟木扎美拉山岩崩体动力过程三维数值分析模型,对危岩崩塌体可能危害的范围及运动规律等进行了定性、定量分析研究。得出如下几点结论: (1)扎美拉山崩塌规模大,危害严重,历时长,成因复杂。陡峻的斜坡地形是崩塌发生的基础条件,坡体结构和地层岩性是崩塌形成的有利因素,降雨、地下水和地表水、地震、风化等是长期影响崩塌形成的外部条件。在强降雨、冰雪水冲刷及强地震等诱发因素作用下,仍有发生崩塌的可能. (2)扎美拉山崩塌岩体的运动路径为:崩塌块石启动后,首先沿东南方向运动,少量岩崩碎屑停留在扎美拉沟内,个别块石越过樟木沟落于樟木滑坡体上。绝大部分岩块运动至樟木沟受阻后转向西南顺沟向下运动,部分停留在樟木沟内,另一部分运动至波曲河后停止;在24s时,岩崩颗粒到达扎美拉沟,速度达到最大值约80m/s。 (3)扎美拉山危岩崩塌体主要危害对象为樟木镇武警二营~樟木沟沿线一带,主要影响停车场、加油站、318公路约300米、住户(30~40户),约300多人的安全。将岩崩的危害范围划分为严重区和影响区,危害严重区面积约48万m2,影响区面积约25万m2。
Other AbstractAs a mountainous country, two-thirds area of our country is mountainous area and mainly concentrates on west regions. Due to the multiple, rich rainfall, frequent earthquake, specific terrain, geological environment and climatic condition of the west regions, it has a frequency occurring district of geological calamity. Rock avalanche disaster is one of the common geological disasters and difficult to predict in the west because of some characteristics as sudden, high speed, high energy, long distance and wide range of it. According to the survey of geological disasters in the 290 counties and cities of our country, the proportion of rock avalanche disaster in geological disasters is up to 17% and rock avalanche disaster is the second largest geological disaster type in addition to the landslide. Rainfall, earthquake and human engineering activities are the mainly factors which may lead to rock avalanche disaster. In recent years, rock avalanches disaster becoming increasingly serious and causes significant casualties and property losses. However, it is hard to meet the demand of the economic development and public safety of our country due to a weak research base of rock avalanche hazard. In this paper, for the difficulty of the investigation and hazard prevention practice of rock avalanches disaster, based on the geological disasters mechanical model research, explore the dynamic evolution of formation, movement and accumulation of rock avalanche, reveal the crack extending the mechanics mechanism of instability of dangerous rock, research on dynamic process and mechanism of rockfall debris flow, reveal the dynamic interaction mechanism of rock avalanche on hazard-affected body, provide the basis for potential rock avalanche disaster identification, quantitative risk assessment and key technology research of disaster reduction. The main conclusions of this thesis are summarized as follows: 1. Preliminarily reveal the macro microscopic mechanism about the unstable rock of crack propagation Basing on the theory and methods of micromechanics and using the laboratory experiment to study the micro-dynamic damage evolution process and the mechanical properties of the rock sample. The fracture mechanics theories were used to study the cracking and expansion mechanism about the typical rock cracks. The microscopic cracks and macroscopic damages were revealed in this paper. 2. Reveal the quantitative effect of the rock avalanche property, scale and slope gradient on the mobility Constructed a small-scale rock avalanche dynamic evolution model laboratory system with unconfined. Some parameters were studied such as particle size, shape, the scale of the original area of rock avalanches, and slope angle, which have the effect to the factors about rock avalanches such as equivalent friction angle, moving distance, depth and length of the deposition about avalanches. The conclusions are summarized as follows: (1) In the same experimental conditions, the particle size has more influence to the moving distance and the equivalent friction coefficient of rock avalanches. The bigger the particles’ scale is, the longer of the rock avalanches’ moving distances are. The depth of deposition of the rock avalanches have inversely relations with the particles’ scale, however, the width of deposition of the rock avalanches have proportional relations with the particle’s scale. What’s more, it also affect the equivalent friction coefficient and the bigger particles will make the avalanches have the strong mobility. (2) The larger the volume of rock avalanches is, the closer of the moving distances about the center of gravity of this disaster is, the longer of the length of the deposition is, the larger of the equivalent friction coefficient is. However, the shapes of the deposition about rock avalanches with different particle sizes are all the same. (3) With the increasing of the numbers of the experiments, the length a
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/15058
Collection山地灾害与地表过程重点实验室
Affiliation中国科学院成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
王忠福. 岩崩灾害形成演化机理研究[D]. 北京. 中国科学院大学,2015.
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