【摘要】：作為歷史悠久的一種壩型,土石壩因其構(gòu)造簡單、施工技術(shù)要求低、成本較低等優(yōu)點,被廣泛運用于水利工程、尾礦壩等建設(shè)之中。在紅土覆蓋的廣泛區(qū)域,主要采用塊狀和團(tuán)粒狀紅土作為壩殼和防滲體的原料,從災(zāi)害地質(zhì)的角度可以認(rèn)為,土石壩屬于人工地質(zhì)體。由于技術(shù)和歷史的原因,這類大壩頻繁出現(xiàn)滲漏、塌陷等病險狀況,大多存在滑坡、潰決、泥石流隱患,嚴(yán)重威脅人民生命財產(chǎn)安全。迄今為止,在對紅土壩加固時均采用一般土石壩的修繕技術(shù),忽視加固材料對筑壩紅土的長期侵蝕,由此造成了愈加固土壩病險狀況愈嚴(yán)重的怪現(xiàn)象。在國家自然科學(xué)基金項目(滲流誘發(fā)紅土滑坡的防滲新模式探索,41462013)的資助下,通過土工試驗、化學(xué)分析、離子檢測、電鏡觀察,并結(jié)合有限元分析和實例驗證,針對堿侵蝕后的紅土大壩進(jìn)行了研究。在遭受堿性物質(zhì)侵蝕的土壩中,滲流和應(yīng)力相互作用,對涉水斜坡的穩(wěn)定性產(chǎn)生了顯著的劣化效應(yīng),故引入滲流應(yīng)力耦合分析方法探析病險紅土壩的安全性能。初步結(jié)論如下:在堿性物質(zhì)侵蝕下,紅土中原有的化學(xué)鍵被破壞,膠結(jié)物質(zhì)被不斷消耗;土顆粒逐漸分解并被壓力滲水帶出土體,使得顆粒之間的孔隙增大,出現(xiàn)架空和滲漏通道。隨著化學(xué)反應(yīng)深入進(jìn)行,筑壩土料中鋁、鈦和二氧化硅的損失加劇,滲透系數(shù)、壓縮系數(shù)明顯增大,而粘聚力、比重、內(nèi)摩擦角都有明顯下降,故酸性紅土與加固材料中的堿性物質(zhì)發(fā)生化學(xué)反應(yīng),是壩料指標(biāo)劣化的根本原因。隨著堿侵蝕加劇,壩體浸潤線和溢出點明顯上升,滲流量顯著增加,同時壩體的位移和應(yīng)力也增大;由于壩料的物理力學(xué)指標(biāo)劣化,滲水的浮托、滲壓、潤滑、溶蝕等不利作用凸顯,壩坡的穩(wěn)定性因此顯著下降。應(yīng)用滲流應(yīng)力耦合分析方法,對龍林水庫紅土壩的安全性能進(jìn)行了研究,獲得了與大壩安全鑒定一致的結(jié)果。在遭受堿性物質(zhì)侵蝕的紅土中,滲流和應(yīng)力相互作用,對涉水斜坡的穩(wěn)定性產(chǎn)生了顯著的劣化效應(yīng),因此滲流應(yīng)力耦合分析方法或能為堿蝕紅土堤壩的安全鑒定提供參考。
[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.
【學(xué)位授予單位】：昆明理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TV223.4;TV641

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