Three–dimensional Analysis of Seismic Stability and Failure Process of Lijie Landslide in Gansu Province, China
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摘要:
针对甘肃省舟曲县立节镇北山滑坡在地震情况下的稳定性及失稳后可能威胁的范围问题,笔者使用显式有限元及动力学大变形方法分析了该滑坡在地震情况下的稳定性及失稳后的破坏过程。首先基于滑坡纵剖面建立二维平面应变模型分析滑坡稳定性及破坏过程,之后使用航测点云数据建立三维滑坡模型进行计算分析。地震条件下三维计算确定的滑坡安全系数结果低于1.0,较二维计算结果低7.7%;三维情况计算出的滑动距离达1.73 km,高于二维情况17%,说明滑坡灾害问题使用二维小变形方法得出结果偏于危险。笔者采用显式有限元、三维及大变形计算方法分析更符合实际,可为滑坡灾害的工程防治提供科学理论依据。
Abstract:The seismic stability and failure process of Lijie landslide is analyzed using the explicit finite element method with dynamic and large deformation modes. Firstly, the Lijie landslide seismic stability is analyzed with two–dimensional plane strain assumption. Then, a three–dimensional mountain model is established via the point cloud data, and three–dimensional landslide failure process analysis is processed to determine the maximum sliding distance and failure range of the landslide. The results obtained by the explicit finite element, three–dimensional and large deformation method in this paper is more accurate than that of the two–dimensional and small deformation method. This study will propose the theoretical guidance for earthquake resistance and the prevention of earthquake–induced landslide disaster.
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表 1 甘肃地区典型地震及诱发滑坡统计表
Table 1. Typical earthquakes and landslides in Gansu
时间 震中 震级(M) 烈度 滑坡灾害特点 1654 甘肃天水 8 XI 密集滑坡群 1718 甘肃通渭 7½ X 密集滑坡群,
遇难人数占总数2/31927 甘肃古浪 8 XI 密集滑坡群 2013 甘肃岷县 6.6 Ⅷ 成片及密集分布 表 2 计算参数取值表
Table 2. The parameter value list
Gmax (MPa) Poisson's ratio ν γref a Dmax c(kPa) φ (°) 40.0 0.25 0.10 0.5 0.200 30 20.0 表 3 输入地震波特征信息表
Table 3. Characteristics of the input earthquake motions
地震加速度时程 Northridge(美国) Kocaeli(土耳其) 记录站点 CDMG(24278) Yarimca(KOERI330) 发生时间 1994年1月17日 1999年8月17日 地震动显着持时(秒) 9.06 15.62 峰值加速度(g) 0.56830 0.349 表 4 滑坡滑动距离计算结果列表
Table 4. Calculation result of slide distance
模型 滑坡状态 安全系数 变形/滑动距离(m) 二维 临界滑动状态 --- 5.36 失稳滑动 1.05 1767.54 三维 临界滑动状态失稳滑动 ---0.96 38.262052.46 -
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