碱侵蚀后红土大坝的渗流应力耦合研究
发布时间：2019-04-24 08:38
【摘要】：作为历史悠久的一种坝型,土石坝因其构造简单、施工技术要求低、成本较低等优点,被广泛运用于水利工程、尾矿坝等建设之中。在红土覆盖的广泛区域,主要采用块状和团粒状红土作为坝壳和防渗体的原料,从灾害地质的角度可以认为,土石坝属于人工地质体。由于技术和历史的原因,这类大坝频繁出现渗漏、塌陷等病险状况,大多存在滑坡、溃决、泥石流隐患,严重威胁人民生命财产安全。迄今为止,在对红土坝加固时均采用一般土石坝的修缮技术,忽视加固材料对筑坝红土的长期侵蚀,由此造成了愈加固土坝病险状况愈严重的怪现象。在国家自然科学基金项目(渗流诱发红土滑坡的防渗新模式探索,41462013)的资助下,通过土工试验、化学分析、离子检测、电镜观察,并结合有限元分析和实例验证,针对碱侵蚀后的红土大坝进行了研究。在遭受碱性物质侵蚀的土坝中,渗流和应力相互作用,对涉水斜坡的稳定性产生了显著的劣化效应,故引入渗流应力耦合分析方法探析病险红土坝的安全性能。初步结论如下:在碱性物质侵蚀下,红土中原有的化学键被破坏,胶结物质被不断消耗;土颗粒逐渐分解并被压力渗水带出土体,使得颗粒之间的孔隙增大,出现架空和渗漏通道。随着化学反应深入进行,筑坝土料中铝、钛和二氧化硅的损失加剧,渗透系数、压缩系数明显增大,而粘聚力、比重、内摩擦角都有明显下降,故酸性红土与加固材料中的碱性物质发生化学反应,是坝料指标劣化的根本原因。随着碱侵蚀加剧,坝体浸润线和溢出点明显上升,渗流量显著增加,同时坝体的位移和应力也增大;由于坝料的物理力学指标劣化,渗水的浮托、渗压、润滑、溶蚀等不利作用凸显,坝坡的稳定性因此显著下降。应用渗流应力耦合分析方法,对龙林水库红土坝的安全性能进行了研究,获得了与大坝安全鉴定一致的结果。在遭受碱性物质侵蚀的红土中,渗流和应力相互作用,对涉水斜坡的稳定性产生了显著的劣化效应,因此渗流应力耦合分析方法或能为碱蚀红土堤坝的安全鉴定提供参考。
[Abstract]:As a kind of dam with a long history, the earth-rock dam has been widely used in the construction of water conservancy projects and tailings dams because of its simple structure, low construction technical requirements and low cost. In the extensive area covered by red soil, massive and granular red soil is mainly used as the raw material of dam shell and impervious body. From the point of view of disaster geology, the earth-rock dam belongs to artificial geological body. Due to technical and historical reasons, this kind of dam frequently appears leakage, collapse and other dangerous conditions, most of them exist landslide, collapse, debris flow hidden danger, which seriously threaten the safety of people's life and property. Up to now, the repairing technology of common earth-rock dam has been adopted in the reinforcement of red earth dam, and the long-term erosion of reinforcing material on red earth dam has been neglected, which results in the more serious the dangerous situation of the earth dam strengthened by the earth dam. Supported by the National Natural Science Foundation of China (Exploration of a New seepage Prevention Model for seepage-induced laterite landslides, 41462013), through geotechnical tests, chemical analysis, ion detection, electron microscope observation, and combined with finite element analysis and practical verification, The red earth dam after alkali erosion is studied. The interaction of seepage and stress in the earth dam subjected to alkaline material erosion has a significant deterioration effect on the stability of the slope involved in water. Therefore, the coupling analysis method of seepage stress is introduced to analyze the safety performance of the dangerous red earth dam. The preliminary conclusions are as follows: under the erosion of alkaline substances, the original chemical bonds in red soil are destroyed and the cementitious substances are consumed continuously; Soil particles are gradually decomposed and taken out of the soil by pressure seepage, resulting in the increase of pores between particles, and the emergence of overhead and leakage channels. With the deepening of chemical reaction, the loss of Al, Ti and Sio _ 2 in dam materials is aggravated, the permeability coefficient and compression coefficient are obviously increased, while the cohesion, specific gravity and internal friction angle are obviously decreased. Therefore, the chemical reaction between acidic laterite and basic material in reinforcement material is the basic reason for the deterioration of dam material index. With the aggravation of alkali erosion, the infiltration line and overflow point of dam body are obviously increased, and the seepage discharge is significantly increased, and the displacement and stress of dam body are also increased. Due to the deterioration of physical and mechanical indexes of dam material, the adverse effects of floating support of seepage, seepage pressure, lubrication, dissolution and so on, the stability of dam slope is obviously decreased. By using the coupling analysis method of seepage stress, the safety performance of Hongtu dam in Longlin Reservoir is studied, and the results are consistent with the safety appraisal of the dam. The interaction of seepage and stress in the red soil subjected to alkali erosion has a significant deterioration effect on the stability of the slope. Therefore, the coupling analysis method of seepage stress may provide a reference for the safety assessment of the alkali-eroded laterite dykes.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV223.4;TV641
本文编号：2464306
[Abstract]:As a kind of dam with a long history, the earth-rock dam has been widely used in the construction of water conservancy projects and tailings dams because of its simple structure, low construction technical requirements and low cost. In the extensive area covered by red soil, massive and granular red soil is mainly used as the raw material of dam shell and impervious body. From the point of view of disaster geology, the earth-rock dam belongs to artificial geological body. Due to technical and historical reasons, this kind of dam frequently appears leakage, collapse and other dangerous conditions, most of them exist landslide, collapse, debris flow hidden danger, which seriously threaten the safety of people's life and property. Up to now, the repairing technology of common earth-rock dam has been adopted in the reinforcement of red earth dam, and the long-term erosion of reinforcing material on red earth dam has been neglected, which results in the more serious the dangerous situation of the earth dam strengthened by the earth dam. Supported by the National Natural Science Foundation of China (Exploration of a New seepage Prevention Model for seepage-induced laterite landslides, 41462013), through geotechnical tests, chemical analysis, ion detection, electron microscope observation, and combined with finite element analysis and practical verification, The red earth dam after alkali erosion is studied. The interaction of seepage and stress in the earth dam subjected to alkaline material erosion has a significant deterioration effect on the stability of the slope involved in water. Therefore, the coupling analysis method of seepage stress is introduced to analyze the safety performance of the dangerous red earth dam. The preliminary conclusions are as follows: under the erosion of alkaline substances, the original chemical bonds in red soil are destroyed and the cementitious substances are consumed continuously; Soil particles are gradually decomposed and taken out of the soil by pressure seepage, resulting in the increase of pores between particles, and the emergence of overhead and leakage channels. With the deepening of chemical reaction, the loss of Al, Ti and Sio _ 2 in dam materials is aggravated, the permeability coefficient and compression coefficient are obviously increased, while the cohesion, specific gravity and internal friction angle are obviously decreased. Therefore, the chemical reaction between acidic laterite and basic material in reinforcement material is the basic reason for the deterioration of dam material index. With the aggravation of alkali erosion, the infiltration line and overflow point of dam body are obviously increased, and the seepage discharge is significantly increased, and the displacement and stress of dam body are also increased. Due to the deterioration of physical and mechanical indexes of dam material, the adverse effects of floating support of seepage, seepage pressure, lubrication, dissolution and so on, the stability of dam slope is obviously decreased. By using the coupling analysis method of seepage stress, the safety performance of Hongtu dam in Longlin Reservoir is studied, and the results are consistent with the safety appraisal of the dam. The interaction of seepage and stress in the red soil subjected to alkali erosion has a significant deterioration effect on the stability of the slope. Therefore, the coupling analysis method of seepage stress may provide a reference for the safety assessment of the alkali-eroded laterite dykes.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV223.4;TV641
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