金沙江白格“11.29”滑坡成因机理及堵江风险分析

    Analysis of the Cause Mechanism and Blockage Risk of the Jingsha River Baige 11.29 Landslide

    • 摘要: 在金沙江白格滑坡经历了2018年10月和11月的两次堵江后,其后缘上编号为K1、K2、K3的三处残留崩滑体规模较大,有再次滑落堵江的可能性。在2022年11月29日至11月30日部分块体发生滑坡,幸未发生滑坡堵江灾害,但稳定安全问题不容乐观。针对新发险情,本文对白格滑坡残留体开展工程地质调查、物探、地表位移监测等工作,查明了K1~2、K1~3两处残留体历史变形破坏现象与潜在失稳规模;同时利用PFC3D颗粒离散元数值模拟技术,建立ball~wall模型,预测两处残留体可能失稳情况的运动过程与堆积形态,并用“四棱台堵江计算”方法进行验算,对残留体堵江风险进行科学评价。结果表明:K1~3块体现处于蠕滑阶段,变形较大,存在整体下滑趋势,其南侧K1~2块体变形较小,整体破坏可能性较低;极端情况下,若K1~3整体下滑导致K1~2块体失稳,二者一同整体破坏,会在金沙江上形成坝高约46m的堰塞体,存在一定的滑坡堵江风险。

       

      Abstract: The Baige Landslide of Jinsha River experienced two river blocks in October and November 2018. The remaining landslide bodies K1, K2, and K3 at the rear edge are large in scale, posing a possibility of sliding and blocking the river again. From November 29 to November 30, 2022, significant deformation occurred in part of the block, indicating unfavorable stability and safety conditions. In response to this new hazard, an engineering geological survey, geophysical exploration, and surface displacement monitoring were conducted on the residual body of Baige landslide. Historical deformation and failure phenomena as well as potential instability scales of K1~2 and K1~3 residual bodies were identified. Additionally, a PFC3D particle discrete element numerical simulation technology was used to establish a ball~wall model for predicting the motion process and accumulation pattern of possible instabilities at two locations. The "four~edge platform calculation" method was employed to scientifically evaluate the risk of the residual body blocking the river. The results indicate that the K1~3 block is currently in a creep stage with significant deformation showing an overall downward trend. The southern K1~2 block exhibits minimal deformation with low overall failure probability. However, under extreme circumstances where an overall slide of K1~3 leads to instability in K1~2 blocks resulting in their combined damage, a barrier body with a dam height of approximately 46m could form on Jinsha River presenting certain risk of landslide~induced river blockage.

       

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