川东巴中市恩阳区近水平土质滑坡破坏模式及专业监测预警

Damage patterns of near-horizontal soil landslides and professional monitoring and warning in Enyang District， Bazhong City， East Sichuan

摘要:

巴中市恩阳区属于典型川东北红层区域，近几年大量的人类工程活动及强降雨极易诱发浅表层土质滑坡，对人民的生命财产造成威胁。本文通过对巴中市恩阳区近3年（2020—2022年）新增的25处近水平土质滑坡进行统计分析，建立了区域典型的土质滑坡地质模型：此类近水平土质滑坡的基本特征为岩层倾角和地形坡度均在10°以内（多为3°~5°），呈近水平状，滑体土层厚度前缘薄，后缘厚，且滑坡前缘存在高陡临空面，岩、土分界面明显。在此基础上定性分析了此类滑坡的变形破坏模式：前缘滑移-拉裂，次级剪切滑动，逐级牵引滑移，整体滑动变形。选择区内一处典型的近水平土质滑坡为研究对象，以滑坡前缘和中后部地表位移为主要监测对象，并监测降雨强度，通过GNSS地表位移监测站、裂缝位移计、雨量计等监测设备对滑坡开展专业监测，监测数据表明，近水平土质滑坡的实际变形破坏模式与理论分析结论基本一致。本文的研究结论可为区内同类型滑坡在设计专业监测方案，制定精准防灾避险措施时，提供一定的理论支撑。

Abstract:

Enyang District in Bazhong City belongs to the typical red layer area in northeast Sichuan. In recent years， shallow surface soil landslides are very easy to be induced by a large number of human engineering activities and heavy rainfall， which pose a threat to people’s lives and properties. In this paper， a typical geological model is established through analyzing the 25 new near-horizontal soil landslides in Enyang District of Bazhong City in the last 3 years（year 2020-2022）. The basic characteristics of such near-horizontal soil landslides are that the dip angle of rock layer and topographic slope are within 10° （mostly 3°~5°）， which are nearly horizontal， the thickness of soil layer of the slide body is thin at the front edge and thick at the back edge， moreover， a high and steep free face at the front edge of the landslide exists and the interface between rock and soil is obvious. The deformation and damage mode of the landslide is qualitatively analyzed as follows： leading edge slip-tensioning， secondary shear sliding， step-by-step traction sliding， and overall sliding deformation. A typical near-horizontal soil landslide in the area was selected as the study object， and the leading edge and middle-rear surface displacements of the landslide were taking as the main monitoring objects. The rainfall intensity was monitored， and the landslide was professionally monitored by GNSS surface displacement monitoring station， fractometer displacement meter， rainfall meter and other monitoring equipment. The results show that the actual deformation and damage patterns of near-horizontal landslides are basically consistent with the theoretical analysis. The findings of this paper can provide some theoretical support for the same type of landslides in the region when designing professional monitoring programs and formulating precise disaster prevention and avoidance measures.