基于固有振动频率的危岩块体稳定评价模型研究

发布时间：2018-03-20 07:26

本文选题：危岩块体　切入点：安全评价　出处：《北京科技大学》2016年博士论文　论文类型：学位论文

【摘要】：边坡危岩块体的稳定性问题是工程地质和岩土工程两大学科中的基本课题之一,近些年来,随着经济的发展,交通、水利、能源工程的建设,出现了大量的人工边坡和被改造后的天然边坡,危岩块体失稳破坏现象越来越多,给当地人民的生命财产造成不可挽回的损失的同时,也给公路、铁路等交通运输安全带来严重隐患。因此,对危岩破坏崩塌进行研究,尤其是其稳定性的分析判别对于地质灾害防灾减灾领域具有极强的现实意义。危岩块体的稳定性主要取决于岩块体本身与边坡岩体的粘结程度,基于结构动力学理论,粘结力的变化必然会引起岩体振动特性发生变化。论文以边坡危岩块体快速识别、安全评价及监测预警为研究目标,主要研究固有振动频率与危岩块体稳定性的动态关系模型,通过非接触的远程激光测振方法与传统传感器的测试数据成果对比分析,建立基于动力特征参数的危岩块体快速安全评价方法并进行监测预警方法研究。本论文分别从理论研究、实验模型与现场应用等方面对固有振动频率与危岩块体的安全稳定性关系模型进行研究,主要结论如下：(1)基于振动力学原理,建立固有振动频率与粘结力理论关系模型,由模型可知,固有振动频率的变化能够反应危岩块体的粘结强度的变化,频率分析能够在第一时间反应边坡危岩块体的损伤状况。(2)通过理论模型研究,可以分析不同时刻抗滑力指标的变化情况,并分析出边坡危岩块体破坏的三个阶段：强稳定阶段、弱稳定阶段和破坏阶段。(3)通过实验发现,随着潜在滑移面粘结力的减少,固有振动频率从原有12.67Hz逐渐下降至4.67Hz,对粘结力指标有很好的指示作用。随着危岩块体潜在滑移面粘结系数的降低,固有振动频率会首先发生变化,在200-230s期间发生大幅度下降；而位移指标则在220-230s时才发生相应变化,基于固有振动频率的最佳预警时段要早于位移预警20s。(4)由摩擦力预警实验可知,摩擦力指标在强稳定阶段基本不发生作用,而在弱稳定阶段中逐渐增大并占据整个抗滑力的80%以上,最终达到最大静摩擦力时产生破坏。实验中,以摩擦力是否达到最大摩擦力为破坏判别标准,其预警时效性优于位移预警30s。(5)通过监测的固有振动频率的变化来对极限平衡模型中的粘结力指标进行动态调整,并对极限平衡分析模型安全系数公式进行修正,实验结论可知,基于粘聚力动态参数计算的安全系数,与实验结果基本相符。(6)基于固有振动频率与滑动面粘聚力关系模型,对三维极限平衡的4种理论模型公式进行修正,计算结果显示,经过大雨等扰动后,边坡危岩块体的三维安全系数由原来的1.3下降到1.1,与实际观察结果相符。(7)基于远程激光测振的应用研究发现,激光多普勒测振仪可实现固有振动频率等动力特性指标的远程监测,通过与传统传感器的对比研究发现其在测量精度和损伤识别方面具有优势。(8)激光多普勒测振仪具备非接触式、高敏感度和模糊识别等优势,在技术上可以快速测量边坡危岩块体的固有振动频率。基于前期的实验研究和三维极限平衡模型,可对危岩块体的安全系数进行快速评价,并可形成一套基于振动特性监测为主、应力应变监测和环境量监测为辅的监测预警方法。
[Abstract]:The problem of slope stability of dangerous rock mass is one of the basic problems of engineering geology and geotechnical engineering department in two universities in recent years, with the development of economy, traffic, water conservancy construction, energy engineering, the artificial slope and natural slope being transformed by the large number of dangerous rock mass failure phenomenon more and more, irreparable damage to the local people's life and property at the same time, but also to the highway, railway and other transportation safety have serious problems. Therefore, the destruction of the rockfall was studied, especially the very strong practical significance to distinguish the field of geological disaster prevention and mitigation is the analysis of the stability. The bonding degree of dangerous rock mass stability mainly depending on the rock mass and rock slope, based on the theory of structural dynamics, the change of adhesion will cause the vibration characteristics of rock mass change. The slope of rock block Rapid identification, safety evaluation and monitoring as the research object, mainly studies the dynamic relationship model of natural vibration frequency and rock block stability analysis results, comparing the test data through remote laser vibrometer non-contact method with traditional sensor, based on the rock block fast safety evaluation method of dynamic characteristic parameters and Study on monitoring and early warning methods. This paper from the theoretical research, study on safety and stability of the relationship model of natural vibration frequency and rock block of experimental model and field application, the main conclusions are as follows: (1) based on the principle of mechanical vibration, a natural vibration frequency and cohesion theory model, the model shows that the change of natural vibration frequency to change the bond strength of reaction of dangerous rock mass, frequency analysis can damage in the first time response slope rock block (2). Through the study of theoretical model can analyze the different time changes of anti slide force index, and analysis of the slope rock block failure in three stages: the strong weak stable stage, stable stage and failure stage. (3) found through experiments, with the reduction of the potential slip surface bond force, natural vibration frequency gradually from the original 12.67Hz dropped to 4.67Hz, is a good indication of bond index. With the decrease of rock block potential slip surface adhesion coefficient, natural frequency will first change occurs during 200-230s decreased significantly; and the displacement index in 220-230s is changed, the best early warning of natural vibration frequency to early period in the early warning based on 20s. displacement (4) by friction early-warning experiment shows that friction index in strong stable stage did not work, and in the weak stable stage gradually increases and occupy the entire anti slide More than 80% finally reached the maximum force and static friction force damage. In the experiment, in order to reach the maximum friction friction is as the failure criterion, the warning time is better than that of 30s. (5) warning displacement by changing the natural frequency of vibration monitoring to bond index limit equilibrium model in dynamic adjustment and the limit balance analysis model of safety coefficient formula is modified, the experimental results show that the calculation of safety factor of cohesion based on dynamic parameters, basically consistent with the experimental results. (6) the natural vibration frequency and sliding surface cohesion relation model based on 4 theoretical models on three dimensional limit equilibrium formula is modified, the calculation results show that after the heavy rain. After the disturbance, 3D safety factor of slope rock mass was reduced from 1.3 to 1.1, the results are consistent with the actual observation. (7) application of remote laser vibrometer based on the findings of, Laser Doppler vibrometer can realize remote monitoring of natural vibration frequency of the dynamic characteristics, compared with the traditional sensor and found that it has advantages in accuracy and damage identification. (8) laser Doppler vibrometer with non-contact, high sensitivity and fuzzy recognition and other advantages, can rapid measurement of natural frequency of slope rock block in technology. Experimental study and three-dimensional limit equilibrium model based on the previous, which can be used to quickly evaluate safety factor of rock block, and can form a set of vibration monitoring based on the main monitoring and early warning method for stress monitoring and environmental monitoring should be.

【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TU45

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