Research on the south side landslide at west open-pit coal mine in Fushun City, Liaoning Province of China
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摘要:
辽宁抚顺西露天矿始采于1901年,全面停采于2018年,台阶式煤炭采掘方式形成了深约420 m的“亚洲第一大坑”。西露天矿南帮滑坡是一个巨型顺层岩质滑坡。滑坡东西长约3100 m,南北宽约1500 m,均厚近100 m,体积约4.52 ×108 m3。降雨、融雪渗流和矿坑底部开挖卸载是导致滑坡形成并持续长距离运动的主要因素。降雨、融雪渗流导致岩体夹层软化、地下水浮托和中前部孔隙水压力作用。2012—2019年的监测数据显示,南帮滑坡累积最大水平位移量达96.01 m,累积最大下沉56.65 m,滑坡前缘最大抬升23.61 m,完全改变了滑坡前的地貌形态。滑坡运动经历了破坏失稳(2010—2012年)、阶跃演进(2013—2016年)和缓变趋稳(2017年以来)3个阶段,反映了巨型滑坡从顺层山体整体破坏、快速发展到逐渐稳定的过程。滑坡敏感性分析显示,地下水位上升对滑坡失稳起到重要作用,滑坡前缘填方压脚对提高整体稳定性效果显著。山体中上部顺层抗滑力、下部切层剪切阻力、前缘填方压力、两侧边界阻力、矿坑北帮反力等是滑坡逐渐制动的主要因素,两侧边界形成“卡阻效应”,前缘出现“压力拱效应”。南帮滑坡控制过程是充分利用边界阻力、工程堆载和北帮抵抗反力控制滑坡运动态势,避免了冲击震动作用,是实现滑坡治理“软着陆”的一个典型案例。
Abstract:The west open-pit coal mine at Fushun in Liaoning Province of China was opened in 1901 and closed in 2018.It formed a 420 meters bottomless pit due to stepped coal mining, therefore, is called the largest pit in Asia.The south side landslide in the open-pit coal mine is a giant bedding rock landslide with 3100 meters in length from east to west and 1500 meters in width from north to south.The volume of the landslide is about 452 million cubic meters.Rainfall seepage and excavation unloading at the bottom of the mine are the main factors that lead to the landslide and the continuous long-distance movement.The concrete manifestation includes interlayer softening, groundwater buoyancy, and pore water pressure in the middle and front parts of the slope.The monitoring data from 2012 to 2019 show that the maximum horizontal displacement of the landslide is 96.01 meters, the cumulative maximum subsidence is 56.65 meters, and the full raise of the front edge is 23.61 meters.The topographic feature of the landslide area is greatly changed.The landslide movement has experienced deformation and failure before 2013, step evolution from 2013 to 2016, and gradually stabilization since 2017.The three phases reflect the rapid development of the giant landslide from the complete destruction of the bedding mountain to a gradually stable process.Analysis of the sensibility reveals the uplifting of underground water level plays an important role in decreasing slope stability, and filling soil at the toe of the slope remarkably increase slope stability.Bedding sliding resistance in the middle and upper slope, cut-layers shear resistance in the lower slope, fill pressure in leading edge, boundary resistance of bilateral, and counterforce of the north side are major factors of the gradual braking of landslide.It is manifested as the "block effect" of the boundary and the "pressure arch effect" of the leading edge.Using boundary resistance, stowage, and resistance reaction force to control the landslide process is typical.The impact and vibration effects were avoided, and the soft landing was realized.
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表 1 计算参数取值
Table 1. Calculative parameters of soil and rockmass
序号 部位 天然容重/(kN·m-3) 饱和容重/(kN·m-3) 粘聚力/kPa 内摩擦角/° 1 滑体 22 24 27 24 2 滑动带 18 20 18 16 3 回填土 18 20 20 20 4 滑床(基岩) - - - - -
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