降雨强度与含石量对松散堆积体失稳影响研究
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摘要
地震、工程开挖及风化、侵蚀、搬运等地质作用形成大量的松散堆积体。堆积体中块石含量各异,在降雨诱发下失稳形成滑坡、泥石流等地质灾害,给当地居民生产生活和大型工程造成严重威胁。利用室内大型模型平台开展不同含石量和降雨强度的模型试验,分析含石量和降雨强度变化对松散堆积体变形失稳的影响。研究表明:降雨入渗过程中松散堆积体的体积含水率变化过程可分4个阶段。在Ⅰ阶段堆积体的含水率基本不变,Ⅱ阶段含水率快速增加,达到峰值后进入Ⅲ阶段,在此阶段中出现缓慢回落,降低到一定程度后进入Ⅳ阶段,此后体积含水率再次缓慢增大。含石量越大,相同降雨强度和时间时其体积含水率越小,后缘主张拉裂缝出现的时间越晚,对应的主张拉裂缝的宽度越小,坡体达到失稳破坏的时间越短。当降雨历时相同时,降雨强度越大,则体积含水率越大;降雨强度越大,松散堆积体失稳破坏时的体积含水率越高;不同降雨强度下,松散堆积体的体积含水率变化规律各不相同。降雨强度对松散堆积体的稳定性影响更加明显,降雨强度越大,松散堆积体的主张拉裂缝值越小,其主张拉裂缝出现时间、裂缝最大宽度、失稳时累积最大位移及失稳降雨历时降低越明显。研究结果为灾区松散堆积体降雨过程中失稳灾变的预测预报研究提供参考。
The geological processes, including earthquake, engineering excavation, weathering, erosion and transport caused a large number of loose accumulation bodies. The stone content in these loose accumulation bodies were different, and the instability induced by rainfall leaded to geological disasters including landslides and debris flows, which seriously threaten the production and living of local residents and the operation of large projects. It is thus crucial to conduct the model tests of different stone content and rainfall intensity using the large scale model platform,and to analyze the influence of stone content and rainfall intensity on the deformation and instability of loose accumulation. The results showed that the evolution of volume water content could be divided into four stages during the rainfall process of loose accumulation. The moisture content almost remained unchanged in stageⅠ, and then increased rapidly in stageⅡ. In stage Ⅲ, the moisture content reached its peak value, and then lightly decreased; after this, the moisture content increase slowly in stage Ⅳ. The larger the rock content, the smaller the volume moisture content of the same rainfall intensity and time, and the earlier the tensile failure occurs at the back edge. The smaller width of the corresponding tensile failure, the shorter duration of the slope failure continues. When the rainfall duration was same, the greater the rainfall intensity, the greater the volume moisture content is. The higher the rainfall intensity, the higher the volume moisture content of the loose accumulation body. Under different rainfall intensities, the volume moisture content of loose accumulation body varies with each other. The stability influence of rainfall intensity on loose accumulation body was more obvious. The greater intensity of rainfall, the main tensile cracks of loose deposits were smaller, and the main tensile cracks time, the maximum crack width, and the instability of the maximum displacement cumulative rainfall duration decreased more significantly. The results would provide references for predicting the instability and calamity in loose accumulations during disaster area.
The geological processes, including earthquake, engineering excavation, weathering, erosion and transport caused a large number of loose accumulation bodies. The stone content in these loose accumulation bodies were different, and the instability induced by rainfall leaded to geological disasters including landslides and debris flows, which seriously threaten the production and living of local residents and the operation of large projects. It is thus crucial to conduct the model tests of different stone content and rainfall intensity using the large scale model platform,and to analyze the influence of stone content and rainfall intensity on the deformation and instability of loose accumulation. The results showed that the evolution of volume water content could be divided into four stages during the rainfall process of loose accumulation. The moisture content almost remained unchanged in stageⅠ, and then increased rapidly in stageⅡ. In stage Ⅲ, the moisture content reached its peak value, and then lightly decreased; after this, the moisture content increase slowly in stage Ⅳ. The larger the rock content, the smaller the volume moisture content of the same rainfall intensity and time, and the earlier the tensile failure occurs at the back edge. The smaller width of the corresponding tensile failure, the shorter duration of the slope failure continues. When the rainfall duration was same, the greater the rainfall intensity, the greater the volume moisture content is. The higher the rainfall intensity, the higher the volume moisture content of the loose accumulation body. Under different rainfall intensities, the volume moisture content of loose accumulation body varies with each other. The stability influence of rainfall intensity on loose accumulation body was more obvious. The greater intensity of rainfall, the main tensile cracks of loose deposits were smaller, and the main tensile cracks time, the maximum crack width, and the instability of the maximum displacement cumulative rainfall duration decreased more significantly. The results would provide references for predicting the instability and calamity in loose accumulations during disaster area.
引文
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[14]Wu Yong,He Siming,Pei Xiangjun,et al.Analysis of condition of startup of gully debris flow after earthquake-The hydraulic mechanism of instability of loose deposits in rainfall[J].Rock and Soil Mechanics,2012,33(10):3043-3050.[吴永,何思明,裴向军,等.震后沟道泥石流启动条件--松散堆积体雨中失稳的水力学机制分析究[J].岩土力学,2012,33(10):3043-3050.]
[15]Zuo Zibo,Zhang Lulu,Wang Jianhua.Model tests on rainfall-induced colluvium landslides:Effects of particle-size distribution[J].Chinese Journal of Geotechnical Engineering,2015,37(7):1319-1327.[左自波,张璐璐,王建华.降雨触发不同级配堆积体滑坡模型试验研究[J].岩土力学,2015,37(7):1319-1327.]
[2]Tang Chuan.Activity tendency prediction of rainfall induced landslides and debris flows in the Wenchuan earthquake areas[J].Journal of Mountain Science,2010,28(3):341-349.[唐川.汶川地震区暴雨滑坡泥石流活动趋势预测[J].山地学报,2010,28(3):341-349.]
[3]Pei Laizheng,Zhou Xiaojun,Fang Hua.Type,active characteristics and development trend of rainfall-induced landslides after wenchuan earthquake[J].Bulletin of Soil and Water Conservation,2012,32(5):113-116.[裴来政,周小军,方华.汶川地震震后降雨滑坡的类型、活动特征及发展趋势[J].水土保持通报,2012,32(5):113-116.]
[4]Qi Xin,Tang Chuan,Chen Zhoufeng,et al.Coupling analysis of control factors between earthquake induced landslides and subsequent rainfall induced landsildes in epicenter area of Wenchuan earthquake[J].Journal of Engineering Geology,2012,20(4):522-531.[齐信,唐川,陈州丰,等.汶川地震强震区地震诱发滑坡与后期降雨诱发滑坡控制因子耦合分析[J].工程地质学报,2012,20(4):522-531.]
[5]Yang Jihong,Dong Jinyu,Huang Zhiquan,et al.Large-scale direct shear tests on accumulation body with different stone contents[J].Chinese Journal of Geotechnical Engineering,2016,38(Supp2):161-166.[杨继红,董金玉,黄志全,等.不同含石量条件下堆积体抗剪强度特性的大型直剪试验研究[J].岩土工程学报,2016,38(增刊2):161-166.]
[6]Gong Jian,Liu Jun.Influences of rock proportion on failure process and failure mode of soil-rock-mixture slope with PIV analysis[J].Rock and Soil Mechanics,2017,38(3):696-704.[龚健,刘君.基于PIV分析的含石量对土石混合体边坡破坏过程及模式的影响[J].岩土力学,2017,38(3):696-704.]
[7]Yang Zhongping,Lei Xiaodan,Wang Lei,et al.Impact of stone content to shear properties of soil rock mixture using particle flow code simulation[J].Journal of Engineering Geology,2017,25(4):1035-1045.[杨忠平,雷晓丹,王雷,等.含石量对土石混合体剪切特性影响的颗粒离散元数值研究[J].工程地质学报,2017,25(4):1035-1045.]
[8]Coli N,Berry P,Boldini D.In situ non-conventional shear tests for the mechanical characterization of a bimrock(BimTest)[J].International Journal of Rock Mechanics and Mining Sciences,2011,48:95-102.
[9]Jin Lei,Zeng Yawu,Zhang Sen.Effects of rock block proportion and shape on mechanical properties of cemented soil-rock mixture by large scale triaxial tests[J].Rock and Soil Mechanics,2017,38(1):1-9.[金磊,曾亚武,张森.胶结土石混合体力学特性的块石含量及形状效应大三轴试验研究[J].岩土力学,2017,38(1):1-9.]
[10]Jin Lei,Zeng Yawu,Li Huan,et al.Numerical simulation of large-scale triaxial tests on soil-rock mixture based on DEMof irregularly shaped particles[J].Chinese Journal of Geotechnical Engineering,2015,37(5):829-838.[金磊,曾亚武,李欢,等.基于不规则颗粒离散元的土石混合体大三轴数值模拟[J].岩土工程学报,2015,37(5):829-838.]
[11]Du Guangbo,Ni Wankui.Analysis of the formation mechanism of rainfall induced residual soil landslide[J].Journal of Disaster Prevention and Mitigation Engineering,2016,36(4):565-571.[杜光波,倪万魁.降雨诱发型残坡积土滑坡形成机理分析[J].防灾减灾工程学报,2016,36(4):565-571.]
[12]Dong Hui,Li Zhifei,Fu Helin,et al.A study of the spatial variability of physical characteristics and water-holding characteristics of the residual diluvia gravel[J].Hydro Geology&Engineering Geology,2015,42(3):71-78.[董辉,李智飞,傅鹤林,等.残坡积碎石物理特征与持水性的空间变异性研究[J].水文地质工程地质,2015,42(3):71-78.]
[13]Dong Hui,Huang Runqiu,Luo Xiao,et al.Spatial distribution and variability of infiltration characteristics for shallow slope of gravel soil[J].Chinese Journal of Geotechnical Engineering,2017,39(8):1501-1509.[董辉,黄润秋,罗潇,等.堆积碎石土斜坡浅表入渗的空间分布与变异性研究[J].岩土工程学报,2017,39(8):1501-1509.]
[14]Wu Yong,He Siming,Pei Xiangjun,et al.Analysis of condition of startup of gully debris flow after earthquake-The hydraulic mechanism of instability of loose deposits in rainfall[J].Rock and Soil Mechanics,2012,33(10):3043-3050.[吴永,何思明,裴向军,等.震后沟道泥石流启动条件--松散堆积体雨中失稳的水力学机制分析究[J].岩土力学,2012,33(10):3043-3050.]
[15]Zuo Zibo,Zhang Lulu,Wang Jianhua.Model tests on rainfall-induced colluvium landslides:Effects of particle-size distribution[J].Chinese Journal of Geotechnical Engineering,2015,37(7):1319-1327.[左自波,张璐璐,王建华.降雨触发不同级配堆积体滑坡模型试验研究[J].岩土力学,2015,37(7):1319-1327.]