三峡水库水位升降对土质岸坡塌岸力学影响机制研究
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摘要
三峡库区土质岸坡因水动力条件改变产生大量塌岸,而库水位升降是其重要破坏因子。对此,通过物理模型试验探究了土质岸坡在水位反复升降条件下的塌岸破坏特征、演化过程及力学机制。结果表明,在水位反复升降条件下,土质岸坡发生渐进式变形破坏。随着水位升降次数增加,其变形演化过程为微裂缝出现→微裂隙扩展→裂隙贯穿→滑面形成→部分滑移→裂隙再次出现并扩展→滑面再次形成→再次滑移,岸坡经过多次滑移后坡度趋缓并最终趋于稳定。水位升降造成塌岸的力学机制为浸泡软化、浮托力及渗流力三种力学效应共同作用,但在库水上升和下降的不同阶段三种力学效应对岸坡的作用效果却明显不同,因此岸坡变形破坏特征和程度也有很大差异。在三种力学效应共同作用下,随库水位反复升降岸坡变形破坏表现为表面拉裂及内部压剪破坏并逐渐积累扩展。
Due to the change of hydrodynamic conditions,the soil slope of Three Gorges Reservoir area has appeared a large number of bank collapses.Reservoir water level fluctuation is an important destructive factor.Therefore,the characteristics,evolution process and mechanical mechanism of bank collapse under the repeated water level rise and fall are studied through the physical model test.The results show that the soil slope occurs progressive deformation under repeated water level fluctuation.With the rise and fall frequency increasing,the deformation and evolution process of the soil slope is followed by the appearance of micro cracks,the expansion of micro cracks,cracks penetration,the formation of slip surface,partial slipping,fissures appearance and expanding again,the formation of slip surface an slipping again.After multiple slipping,the slope gradually slows down and eventually becomes stable.Mechanical mechanisms of water level fluctuation to the bank collapse include three kinds of soil soaking softening,floating force and seepage force.However,the effect of the three mechanical effects at different stages of the water level fluctuation are obviously different,so there is a difference in the characteristics and the degree of slope deformation.Under the combined action of these effects,the deformation of slope are manifested by surface fracturing and internal pressure shear failure along with the repeated rise and fall of the reservoir water level,and gradually accumulate and expand.
Due to the change of hydrodynamic conditions,the soil slope of Three Gorges Reservoir area has appeared a large number of bank collapses.Reservoir water level fluctuation is an important destructive factor.Therefore,the characteristics,evolution process and mechanical mechanism of bank collapse under the repeated water level rise and fall are studied through the physical model test.The results show that the soil slope occurs progressive deformation under repeated water level fluctuation.With the rise and fall frequency increasing,the deformation and evolution process of the soil slope is followed by the appearance of micro cracks,the expansion of micro cracks,cracks penetration,the formation of slip surface,partial slipping,fissures appearance and expanding again,the formation of slip surface an slipping again.After multiple slipping,the slope gradually slows down and eventually becomes stable.Mechanical mechanisms of water level fluctuation to the bank collapse include three kinds of soil soaking softening,floating force and seepage force.However,the effect of the three mechanical effects at different stages of the water level fluctuation are obviously different,so there is a difference in the characteristics and the degree of slope deformation.Under the combined action of these effects,the deformation of slope are manifested by surface fracturing and internal pressure shear failure along with the repeated rise and fall of the reservoir water level,and gradually accumulate and expand.
引文
[1]刘海明.中国东南部山区水库塌岸预测研究[D].成都:成都理工大学,2016.
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[6]孙祚浩,王畯才,卢坤林,等.无粘性散粒堆积体滑塌影响区域概率分布的模型试验[J].水电能源科学,2016,34(10):122-124.
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[9]刘顺东,黄尔.龚嘴水库上游再造床特征[C]//第七届全国泥沙基本理论研究学术讨论会论文集,2008.
[2]刘智.冰水堆积体岸坡塌岸模式及成因机制分析---以雅泸公路瀑布沟库区段为例[J].人民长江,2013,44(3):20-24.
[3]白彦波,余鹏程,李渝生.龚咀电站水库塌岸模式研究[J].水土保持研究,2006,13(6):268-270.
[4]王广德,葛华,刘汉超,等.重庆市万州区塌岸模式及影响因素分析[J].中国地质灾害与防治学报,2008,19(3):148-151.
[5]彭仕雄,陈卫东.水库塌岸预测参数取值体系研究[J].长江科学院院报,2014,31(11):56-59.
[6]孙祚浩,王畯才,卢坤林,等.无粘性散粒堆积体滑塌影响区域概率分布的模型试验[J].水电能源科学,2016,34(10):122-124.
[7]许强,陈建君,张伟.水库塌岸时间效应的物理模拟研究[J].水文地质工程地质,2008,35(4):58-61.
[8]许强,白建光,汤明高,等.三峡库区塌岸的物理模拟研究[J].工程地质学报,2007,15(2):154-158.
[9]刘顺东,黄尔.龚嘴水库上游再造床特征[C]//第七届全国泥沙基本理论研究学术讨论会论文集,2008.