DEFORMATION MECHANISM AND EVOLUTIONARY PROCESS OF THE TIANSHUI FORGING MACHINE PLANT LANDSLIDE IN GANSU
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摘要: 天水锻压机床厂滑坡(1.4×106 m3)发生于1990年8月11日, 滑坡体主要由次生黄土组成, 滑床为第四系黄土和新近系泥岩, 滑坡沿黄土-泥岩接触面发生, 属黄土接触面滑坡。通过野外调查和工程钻探对锻压机床厂滑坡变形破坏机制及形成演化进行研究, 结果表明, 该滑坡变形破坏方式表现为滑移-拉裂式, 受区内二元斜坡结构控制, 是在工程切坡和降雨、灌溉等诱发因素作用下形成; 其形成演化经历了高陡边坡形成期→滑坡孕育期→滑动面贯通临界期→滑坡启动下滑堆积期→滑坡复活变形期等过程。该滑坡目前处于欠稳定状态, 遇地震或强降雨等作用, 极有可能再次复活下滑。研究成果可为该类滑坡的防治预警提供理论依据。Abstract: The Tianshui Forging Machine Plant Landslide in Gansu Province happened on August 11, 1990 with a volume of 1.4×106 m3. It is a loess interface landslide occurring along the loess/mudstone interface. The landslide body is mainly composed of secondary loess, and the slip bed is mainly composed of Quaternary loess and Neogene mudstone. The landslide is controlled by the double-layered structure of the slope in area, being induced by some factors such as engineering excavation, rainfall and irrigation. The research on the deformation mechanism and evolutionary process of the landslide based on geological survey and engineering drilling shows that the formation process can be divided as follow: the formation period of high and steep side slopes; the landslide incubation period; sliding surface through critical period; landslide falling and accumulating period; landslide revival and deformation period. Field investigation and engineering drilling indicate that the landslide is unstable at present. It can most likely revive and slide again if there is earthquake or heavy rainfall. The results can provide theoretical basis for the disaster warning of this kind of landslide.
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表 1 天水地区易滑地层物理力学性质统计表[1]
Table 1. Statistics of physical and mechanical properties of easy sliding layers in Tianshui area
岩性 时代 物理性质 抗剪强度 含水量/% 天然容重/(kN·m-3) 干容重/(kN·m-3) 峰值 残余 C/kPa φ/(°) Cr/kPa φr/(°) 干黄土 Q3 10.0~18.2 14.3~15.4 12.8~13.9 24.5~52.0 25.3~31.7 5.0~12.3 22.0~27.5 湿黄土 Q3 21.4~28.0 15.8~17.2 13.5~15.4 5.0~12.5 6.7~17.4 <5 7.0~15.5 弱风化泥岩 N2 3.2~13.5 19.6~25.7 18.4~25.2 90.0~1570.0 18.0~44.2 20.0~293.0 15.4~33.6 强风化泥岩 N2 20.0~30.2 19.4~20.8 14.9~17.2 9.0~35.0 7.4~11.9 7.0~28.0 4.5~7.0 注:C—黏聚力;φ—内摩擦角;Cr—残余黏聚力;φr—残余内摩擦角 表 2 天水锻压机床厂滑坡区岩土的抗剪强度指标[23]
Table 2. Shear strength of rock and soil in Tianshui Forging Machine Plant
岩性 时代 原状土 重塑土 饱和重塑土 C/kPa φ/(°) Cr/kPa φr/(°) Cr/kPa φr/(°) 离石黄土 Q2 85 17.0 50 13.5 15 4.0 泥岩 N 45 13.5 20 4.5 13 2.5 -
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