粤西封开地区花岗岩斜坡变形破坏与降雨响应关系研究

本文在2017~2019年地质灾害调查的基础上，结合降雨监测数据，系统分析了粤西封开地区斜坡变形破坏与降雨的响应关系。结果表明，斜坡变形破坏多发生在汛期（5~8月），且变形破坏模式为“滑移”、“崩落（坠落）”和“倾倒”三种类型，规模均为小型。“软化崩解”、“渐进性破坏”和“刚性破坏”是花岗岩斜坡主要的变形破坏机理。斜坡变形破坏与单日降雨量和累积降雨量密切相关。斜坡变形破坏多发生在单日降雨量为30 ~ 90 mm区间内，其中与50 ~ 60 mm降雨量响应关系最为显著。斜坡变形破坏与累积降雨量具有明显的相关性；在累积降雨量150 ~ 250 mm区间内响应关系最为显著。相对于降雨，部分斜坡变形破坏有一定的滞后性，滞后期为5~7天。因此，在上述降雨阈值区间，区内花岗岩斜坡隐患点应进入应急预警状态。

Study on the Relationship Between Deformation and Failure of Granitoids Slopes and Rainfall Response in the Fengkai Area of Western Guangdong Province

To better understand the responses of granite slope deformation and failure (GSDF) to rainfall, the relationships were analyzed between GSDF and precipitation in Fengkai area of western Guangdong province based on geohazard survey from 2017 to 2019 as well as rainfall monitoring data. Results show that GSDF could be divided into 3 types of sliding, falling, toppling with small dimensions, which typically occur in the flood season (May to August). “Softening and disintegration”, “progressive failure” and “rigid failure” patterns are the major mechanisms of GSDF. Occurrence of GSDF is closely linked to daily and cumulative precipitation. GSDF generally takes place when daily precipitation ranges from 30 to 90 mm, particularly 50 to 60 mm. GSDF is also found to obviously related to cumulative precipitation occurs easily when it is of 150 to 250 mm. Although the GSDF often responds to the rainfall, it may occur 5 to 7 days after raining. Therefore, the hidden geohazard points of granite slopes should be put into early warning stage when precipitation is in the above rainfall threshold range. These results contribute to the strategies of early warning and mitigation of geohazards in granite slopes areas.