基于分布式光纤应变感测的边坡模型试验研究

PHYSICAL MODEL TESTING OF SLOPE STABILITY BASED ON DISTRIBUTED FIBER-OPTIC STRAIN SENSING TECHNOLOGY

光纤传感是近年来发展起来的一种分布式监测技术,这种方法在边坡工程监测领域有着巨大的潜力和应用价值。提出一种通过监测坡体应变分布来实现边坡稳定性评估的新方法,通过一组边坡模型试验,采用布里渊光时域分析(BOTDA)技术,对坡顶加载过程中边坡模型不同深度处的水平向应变进行连续监测。试验结果表明:经过热缩管封装的直埋式紧套光纤适用于边坡应变分布的监测;铺设传感光纤时,在关键位置预留自由段可达到温度补偿和精确定位的双重效果;边坡滑裂面的位置可以通过对分布式应变监测数据的分析大致推算出来。通过分析试验中受荷边坡变形和稳定性状态的演化过程,证明最大水平向平均应变值和边坡安全系数具有一定的经验关系。该研究成果为边坡稳定性评估和滑坡预警提供一种新的思路和方法。

Fiber optic sensing is a newly-developed distributed monitoring technology;it has great potential in slope engineering.A new method to evaluate the stability condition of slope based on strain distribution of slope mass measured by sensing fiber in real-time is proposed.A slope model test is conducted in laboratory and the Brillouin optical time-domain analysis（BOTDA） technology has been used to measure the horizontal strains at different depths of the slope model subjected to loading on the slope crest.The test results show that the tight-buffering optical fiber packaged by heat-shrinkage tubes can be used for monitoring strain distribution within the slope.In order to take temperature compensation into consideration and achieve the purpose of accurate positioning,the installation of loose fiber sections at key locations along the sensing fiber is recommended.The potential slip surface can be estimated based on the distributed strain monitoring results.The deformation behavior and stability condition of the slope model during testing was analyzed in detail.It is found that there is an empirical relationship between the averaged maximum horizontal strains and the factor of safety of slope,so as to provide a new approach to evaluate slope stability and perform early warning of landslides.