基于固有振动频率的危岩安全监测试验研究  

Safety monitoring experiment of unstable rock based on natural vibration frequency

作　　者：杜岩[1,2] 谢谟文[1] 蒋宇静[3] 李博[2] 高阳[4] 刘秋强[5] 

机构地区：[1]北京科技大学土木工程系,北京100082 [2]长崎大学,日本长崎852-8521 [3]山东科技大学矿山灾害预防控制国家重点实验室培育基地,山东青岛266590 [4]石家庄铁道大学大型结构健康诊断与控制研究所,河北石家庄050043 [5]中国地质环境监测院,北京100081

出　　处：《岩土力学》2016年第10期3035-3040,共6页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.41372370,No.41572274);中国博士后科学基金(No.2016M591078);中央高校基本科研业务专项(No.FRF-TP-16-014A1)~~

摘　　要：危岩体在经历地震和强降雨之后其抗滑力下降,从而导致重力作用失稳,是一种常见的破坏形式。危岩块体的失稳破坏取决于岩体结构面的状况,随着结构面的张开及黏结程度下降,危岩块体会发生失稳而崩塌,基于常规位移监测方法难以达到危岩块体监测预警的目的。而固有振动频率可以有效反映岩体的物理力学参数的变化,进而可以对其安全性做出预判。基于模型试验,在保持下滑力不变的情况下,通过固有振动频率来对滑坡内部的黏结力和摩擦力等力学指标进行分析。通过实际静摩擦力是否达到最大静摩擦力的方法来科学判识岩体的稳定情况。试验结果得出:计算的摩擦力可以有效分析岩体的安全性,并证明固有振动频率在降低至6 Hz以下,岩体开始趋于破坏。同时,得出由于摩擦力破坏后期占据抗滑力的比重逐渐升高,最高达到抗滑力的80%,从而造成破坏末期摩擦力不降反升的情况。基于固有振动频率的监测,可对岩体的损伤做出定量判断,也可评估岩体静摩擦力指标,从而实现扰动后岩体的安全评价。这种基于振动模态的岩体安全监测与损伤评价新的技术思路,将在实际工程中发挥重大作用。Reduction of sliding resistance of unstable rock mass after an earthquake and heavy rainfall, is one of the main causes of failures. The instability and failure of unstable rock masses depend on the condition of the surface structure. As cracks open and the cohesive force of the bonding surface decreases, rock blocks become unstable, and then collapse occurs. If the conventional displacement-based monitoring method is adopted, it is generally difficult to achieve the goal of monitoring and early warning. In contrast, natural vibration frequency can effectively demonstrate the changes in physical and mechanical parameters of rock, and thus the safety assessments of unstable rock can be easily made. Through model experiments, the internal cohesive force and friction force of rock under constant sliding force are analyzed based on the natural vibration frequency. The friction force is compared to the maximum static friction force, in order to check whether or not the rock is prone to failure. It is shown that the calculated friction force can be used to effectively represent the safety of rock and the rock fails when the natural vibration frequency is below 6 Hz. The increase of the frictional force is up to 80% of stabilizing force, so that the friction increases rather than decreases in some cases. By monitoring the natural frequency, a quantitative assessment of the rock damage is made, and the static friction force index is identified, providing a new way for safety monitoring and damage evaluation of rocks based on natural vibration frequency.

关 键 词：危岩体 固有振动频率 激光多普勒测振仪 安全监测 预警 

分 类 号：TU458[建筑科学—岩土工程]