半壁山拉断式危岩体风险性评估与防治

发布时间：2018-04-28 19:46

本文选题：拉断式危岩 + 冻融应变　；参考：《成都理工大学》2017年硕士论文

【摘要】：本文以承德市半壁山保护工程为依托工程,通过对研究区的现场调查,借助室内试验,查明半壁山崩塌的发育分布规律,分析拉断式岩体在循环冻融条件下的破裂机制,再从危险性与易损性的角度,评价分析危岩发生崩塌后的风险性,对其运动的距离和威胁范围等方面进行预测,将风险量化,反馈到实际工程中,最终采用优化的治理措施建议,将风险分析研究贯穿工程建设与使用的整个过程。本文主要研究成果如下:(1)研究区内的地质环境及地质灾害的分布发育特征收集研究区的地质环境资料,通过对对半壁山危岩体进行了调查统计结果表明:危岩体分布发育规律主要是受地质构造、地层岩性、结构面特征和气象水文的影响,岩性和区域气候是引起危岩失稳的主要因素,破坏失稳方式多以拉断式(坠落)为主。(2)裂隙岩体冻融变形的影响因素及特征通过冻融应变试验得出不同含水状态的岩体一个冻融周期内的应变曲线存在差异,裂缝未充水岩体在冻结过程中没有冻胀现象。裂隙岩样经过多次冻融循环作用后产生了残余微应变。(3)冻融岩石的物理力学变化特征(1)物理特征:冻融作用引起的质量变化幅度较小。(2)力学特征:a.砂砾岩单轴压缩条件下以剪切破坏为主;不同含水状态的岩样随着冻融循环次数的增加,其单轴抗压强度均成减小趋势。根据试样初始强度与冻融循环后强度分析计算其强度损失率,由计算结果可知:随冻融循环次数的增加,试样单轴抗压强度损失率整体呈增大趋势,并且,经历相同次数的冻融循环作用后,饱和岩样的强度衰减幅度明显大于干燥试样的衰减幅度。b.饱水状态岩样的抗拉强度随着冻融循环次数的增加成减小趋势,强度衰减基本呈线性。根据试样初始强度与冻融循环后强度分析计算其强度损失率。(4)危险性主要指的是危岩体形成灾害的可能性与到达所要保护工程的可能性,将岩性、地质构造、风化荷载、冻融循环情况、坡表植被覆盖情况等5因素赋值,用层次分析法判断各因子所占权重,运用RHRS法融合地质概况、地形特征、气象水文、岩块切割尺寸、崩塌规模、以往崩塌历史等因子,评价坡体危险性,得到量化危岩体风险性值。(5)易损性按照承灾体类型分类,分别评价固定承灾体与流动承灾体。首先计算出滚石到达建筑物时的冲击力,再按照规范计算出路面的抗冲击承载力极限值,固定承灾体的易损性用冲击与抗冲击对比得到概率,结合Peila和Guardini事件树概率分析,计算出最终每年事故死亡率,比较死亡率区分易损性的大小,确定易损性评价。(6)根据前文所分析的危险性评价与易损性评价,相结合评价半壁山危岩体的风险性值,再反馈给实际依托工程,优化治理措施。
[Abstract]:In this paper, based on the protection project of half wall mountain in Chengde city, through the field investigation in the research area and with the help of laboratory tests, the development and distribution of the half wall mountain collapse are found out, and the fracture mechanism of the pull rock mass under the condition of circulation freezing and thawing is analyzed. From the point of view of danger and vulnerability, the risk of collapse of dangerous rock is evaluated and analyzed, the distance of movement and the range of threat are predicted, and the risk is quantified and fed back to the actual project. Finally, the risk analysis is carried out through the whole process of engineering construction and use with the suggestion of optimized management measures. The main research results of this paper are as follows: (1) the geological environment and the distribution and development characteristics of geological hazards in the study area are collected from the geological environment data of the study area. The results of investigation and statistics show that the distribution and development of dangerous rock mass are mainly affected by geological structure, stratigraphic lithology, structural plane characteristics and meteorological hydrology. Lithology and regional climate are the main factors causing instability of dangerous rock. The influencing factors and characteristics of freezing and thawing deformation of fractured rock mass are obtained by freezing and thawing strain test. The strain curves of rock mass with different water content in a freeze-thaw period are different. There is no frost heave in the freezing process of fractured unfilled rock mass. After several freeze-thaw cycles, the fractured rock samples have produced residual microstrain. 3) the physical and mechanical characteristics of frozen and thawed rocks. 1) physical characteristics: the range of mass change caused by freeze-thaw process is smaller than that caused by freeze-thaw process) the mechanical characteristic is: a. Under uniaxial compression, shear failure is dominant, and the uniaxial compressive strength decreases with the increase of freezing and thawing cycles. According to the initial strength of the specimen and the strength analysis after freeze-thaw cycle, the strength loss rate is calculated. The results show that with the increase of freeze-thaw cycle times, the loss rate of uniaxial compressive strength of the sample shows an increasing trend, and the loss rate of uniaxial compressive strength of the specimen increases with the increase of freeze-thaw cycles. After the same number of freeze-thaw cycles, the intensity attenuation of saturated rock samples is obviously larger than that of dry samples. The tensile strength of saturated rock samples decreases with the increase of freeze-thaw cycles, and the strength decay is linear. According to the initial strength of the specimen and the strength analysis after freeze-thaw cycle, the risk of strength loss. 4) the risk mainly refers to the possibility of the dangerous rock mass forming disaster and the possibility of reaching the project to be protected, the lithology, geological structure, weathering load, etc. Five factors, such as freeze-thaw cycle, slope surface vegetation coverage and so on, are assigned. The weight of each factor is judged by analytic hierarchy process (AHP). The RHRS method is used to integrate geological survey, topographic features, meteorology and hydrology, rock block cutting size, collapse scale, and so on. In the past factors such as collapse history and so on, the risk of slope body is evaluated, and the risk of dangerous rock mass is quantified. The vulnerability is classified according to the type of disaster bearing body, and the fixed bearing body and the flowing disaster bearing body are evaluated respectively. First of all, the impact force of the rolling stone to the building is calculated, then the limit value of the road impact bearing capacity is calculated according to the specifications. The probability of the vulnerability of the fixed bearing body is obtained by comparing the impact and the impact resistance, and the probability analysis is combined with the Peila and Guardini event tree probability analysis. Calculate the final annual accident mortality rate, compare the size of the mortality rate to distinguish vulnerability, determine vulnerability evaluation. (6) according to the risk assessment and vulnerability evaluation of the previous analysis, combined with the evaluation of the risk value of the half-wall rock mass, Feedback to the actual rely on the project, optimization of governance measures.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU45

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