西藏笨多高位变形体遥感解译与危险性预测分析

Remote sensing interpretation and risk prediction analysis of Benduo high deformation body in Tibet

以易贡藏布上游笨多高位变形体为例,结合野外地面调查、无人机综合摄影调查、光学遥感动态调查和数值模拟预判等方法,对笨多高位变形体的发育特征及其可能形成灾害链的危险性进行预测分析。研究结果认为:(1)笨多高位变形体位于断层内,岩体破碎、岩体结构面发育、强度较低。目前笨多高位变形体内强烈变形的小型崩塌体12处,裂隙64条。(2)根据InSAR解译结果发现笨多高位变形体共有两处变形区,其中BX1变形区域规模较大,且最大形变速率达到85 mm/a,一旦失稳下滑具有较高的堵江风险。(3)对变形体失稳后危险性预测分析可知,笨多高位变形体发生失稳后会堵塞易贡藏布,堆积体平均厚度为90 m,形成堰塞湖回水长度达25 km。坝体堵塞形成的回水区域对上游的忠玉村溃决后对下游村镇的威胁程度均较高。(4)根据堰塞体的风险特征,探讨了开挖泄洪洞排泄洪水的处理方案。

This article takes the Benduo high deformed body in the upper reaches of Yigong Zangbo as an example,combined with the methods of field ground survey,UAV integrated photographic survey,optical remote sensing dynamic investigation and numerical simulation prediction,the development characteristics and possibility of the Benduo high deformed body are analyzed.Predict and analyze the risk of forming a disaster chain.The results of the study are as follows:(1)The Benduo highposition deformable body is located in the fault,the rock mass is broken,the rock mass structural surface is developed,and the strength is low.At present,there are 12 small collapses and 64 cracks in the strong deformation of Benduo's high deformation body.(2)According to the interpretation results of InSAR,it is found that the Benduo high-position deformable body has two deformation areas.Among them,the BX1 deformation area is larger and the maximum deformation rate reaches 85 mm/a.Once it loses stability and slides,it has a higher risk of blocking the river.(3)Prediction and analysis of the risk of the deformed body after the instability shows that the Benduo high-level deformed body will block the Yigong Zangbu after the instability,the average thickness of the accumulation body is 90 m,and the backwater length of the dammed lake is 25 km.The backwater area formed by the blockage of the dam poses a higher threat to the downstream villages and towns after the failure of the upstream Zhongyu Village.(4)According to the risk characteristics of the dam body,the treatment plan for the excavation of the spillway tunnel is discussed.