MEMS传感器在锚杆加固边坡监测中的应用研究

滑坡破坏各种建筑工程,严重影响了人民生产生活以及国民经济的发展。锚杆作为边坡治理的主要手段之一,其施工质量与锚固效果难以直接监测。随着微机电系统(MEMS)技术的兴起与不断发展,MEMS传感器具有体积小、造价低和精度高等优点,使其从常规监测手段中脱颖而出,为地质工程监测提供了新的可能。通过设计模型试验,基于MEMS传感器探讨锚杆对边坡的加固作用。试验采用天然河砂,通过撒砂法堆坡,边坡坡角为45°,分有锚杆加固和无锚杆加固2组。以降雨触发滑坡,将MEMS传感器布设在边坡内部,实现对边坡内部各点的加速度、角度和角速度的实时连续监测。研究表明:当未加固边坡蠕滑开始时,边坡内部和坡脚处的加速度与角度发生渐变,边坡后缘与表面处的加速度和角度变化不明显,表明边坡蠕滑主要发生在边坡内部与坡脚处;滑坡发生时,边坡内部与坡脚处的加速度和角度率先发生突变,边坡后缘与表面的参数随后发生突变,表明砂土坡破坏的瞬间,其内部与坡脚处先发生滑动,边坡后缘与坡面随后滑动,为典型的牵引式滑坡。采用锚杆加固后,边坡只发生蠕滑,边坡内部、坡脚处与坡面的加速度和角度有明显渐变,边坡后缘的各指标几乎无变化,表明降雨条件下,加固后的边坡发生整体蠕滑,边坡坡角降低,不发生破坏。MEMS传感器能够实现低成本、高精度的连续实时监测边坡蠕滑的渐变规律,捕捉到滑坡发生时运动的明显突变,对研究边坡的滑动机制及滑坡预警有一定的应用价值,在地质工程监测领域具有广阔的应用前景。

Research on the Application of MEMS Sensors to Slope Monitoring Treated by Bolts

The landslide can destroy all kinds of constructions,and seriously hinder people's production and life as well as the development of national economy. Bolt is one of the main methods for slope treatment,but it is difficult to monitor its construction quality and anchoring effect directly. With the rise and development of MEMS(Micro-electro mechanical system)technology,MEMS sensors,with the advantages of small size,low cost and high precision,quickly come out from the conventional monitoring methods and provide new possibilities for the monitoring field in geological engineering. In this paper,based on MEMS sensors,a model test was designed to explore the stability of the slope after treatment by bolts. Natural river sands were used to prepare slopes with angle of 45° through the air-plluviation method. In addition,the tests were divided into two groups(with or without bolts). MEMS sensors were set up in the slope to wirelessly and continually capture the acceleration,angular velocity and angle of slope sliding triggered by simulated rainfall in real-time. It was found that:with no treatment,the acceleration and angle in the interior and the bottom of the slope gradually changed during rainfall,while those parameters in the rear and the surface of the slope had no significant change,which indicated that the slope creep mainly occurred in the interior and the bottom of the slope before failure. When landslides occurred,the movement monitoring indexes in the interior and the bottom of the slope suddenly changed,followed by those in the rear and the surface of the slope,which means that when the sandy slope slides,the interior and the bottom of the slope slides first,and then the rear and the surface of the slope surface fail. This is a typical retrogressive landslide. After the slope was treated by bolts,only creep could be observed during long-term rainfall,and the acceleration and angle in the bottom,interior and surface of the slope gradually changed,while almost no change was found in the rear of the slope,which shows that under rainfall conditions,overall creep occurs for the slope after reinforcement,the slope angle decreases,and there is no landside. The experimental results prove that MEMS sensors can realize low-cost,high-precision,continuous real-time monitoring of slope,and can capture gradual changes of movements before failure and the sudden change when landslide occurs. It should play a certain role in the study of landslide mechanism and landslide warning,and has a broad application in the field of geological engineering monitoring.