| 冻结滞水效应及其促滑机理
——以甘肃黑方台地区为例 |
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| 引用本文： | 张茂省,程秀娟,董 英,于国强,朱立峰,裴 赢.冻结滞水效应及其促滑机理
——以甘肃黑方台地区为例[J].地质通报,2013,32(6):852-860. |
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| 作者姓名： | 张茂省 程秀娟 董 英 于国强 朱立峰 裴 赢 |
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| 作者单位： | 国土资源部黄土地质灾害重点实验室/中国地质调查局西安地质调查中心,陕西西安,710054 |
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| 基金项目： | 中国地质调查局项目，国家科技支撑计划课题 |
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| 摘 要： | 冻融期地质灾害的不断发生,愈来愈引起社会关注并被更多的学者所重视,甘肃黑方台地区冬春交接时期滑坡频发,是研究季节性冻融作用的首选之地.为了探索是否存在冻结滞水效应,揭示冻融作用诱发滑坡灾害机理,建立了气温、地温和地下水位动态等协同观测网.监测数据显示:黑方台地区存在季节性冻融现象,可划分为冻结期(秋冬)、完全冻结期(冬)、冻融期(春夏)、融化期(夏秋)的年季循环过程,也存在昼夜气温变化引起的循环冻融过程；斜坡中段冻结引起的地下水位上升了1.0m,证实了冻结滞水效应的存在.地下水模拟结果表明,冻结滞水引起斜坡坡脚水位壅高幅度超过3m,水平影响距离达到30m以上.冻结前坡体稳定系数为1.19;冻结后仅考虑冻结滞水效应引起的地下水位上升,稳定系数减小到1.09；反复冻融后,考虑黄土强度降低因素,坡体稳定系数降至0.97,说明冻结滞水效应和循环冻融的双重作用是滑坡在春季频发的根本原因.
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| 关 键 词： | 冻融作用 冻结滞水效应 促滑机理 黑方台 |
The effect of frozen stagnant water and its impact on slope stability: A case study of Heifangtai, Gansu Province |
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| ZHANG Mao-sheng,CHENG Xiu-juan,DONG Ying,YU Guo-qiang,ZHU Li-feng,PEI Ying.The effect of frozen stagnant water and its impact on slope stability: A case study of Heifangtai, Gansu Province[J].Geologcal Bulletin OF China,2013,32(6):852-860. |
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| Authors: | ZHANG Mao-sheng CHENG Xiu-juan DONG Ying YU Guo-qiang ZHU Li-feng PEI Ying |
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| Institution: | Key Laboratory for Geo-hazards in Loess Area, MLR/Xi'an Center of Geological Survey, CGS, Xi'an 710054, Shaanxi, China |
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| Abstract: | The frequent landslides during freeze-thaw period have not only caused increasing social concern but also aroused much attention among researchers. With frequent occurrence of landslides during the transition period between winter and spring, Heifangtai of Gansu is the priority for studying the seasonal freeze-thaw action. For the purpose of exploring the problem whether the effect of frozen stagnant water exists or not and revealing the mechanism of landslides induced by freeze-thaw action, a coordinated monitoring network incorporating air temperature, ground temperature and real-time groundwater table was established. The monitored data show that seasonal freeze-thaw phenomena do exist in Heifangtai. The phenomena can be further divided into yearly cycling process which includes the partially frozen period in early winter, the totally frozen period in deep winter, the freeze-thaw period in spring, the melting period in summer, and the daily cycling process which is caused by daily changes of air temperature. The 1.0 m elevation of groundwater table due to the freezing of soils in the middle of the slope confirms the existence of the effect of frozen stagnant water. The groundwater simulation reveals that the effect of frozen stagnant water causes the groundwater table to rise by more than 3m at the toe of the slope and affects a horizontal zone by more than 30m into the slope. The results of slope stability analysis show that the coefficient of slope stability before freezing is 1.19. After freezing, the stability coefficient is reduced to 1.09 if only the groundwater table rise due to the effect of frozen stagnant water is considered. If the reduction of strength of loess after repeated freeze-thaw action is considered, the slope stability coefficient is reduced to 0.97. These data demonstrate that the dual functions of the effect of frozen stagnant water and cyclic freeze-thaw are the fundamental factors responsible for the frequent occurrence of landslides during spring. |
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| Keywords: | freeze-thaw action effect of frozen stagnant water mechanism of promoting landslides Heifangtai |
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