【摘要】：近年來,隨著加筋土技術(shù)越來越廣泛的應(yīng)用,國(guó)內(nèi)外學(xué)者對(duì)加筋土結(jié)構(gòu)特性已進(jìn)行了大量研究。由于巖土體特性及工程實(shí)踐的復(fù)雜性,雖然取得了一定進(jìn)展,但仍無法滿足工程實(shí)踐的需求。目前關(guān)于返包式加筋結(jié)構(gòu)的研究多集中于單級(jí)或多級(jí)(近)直立路肩式加筋土擋墻,其填料多為粘土或砂土,對(duì)于加筋陡坡高路堤結(jié)構(gòu)以及碎石土填料的研究還很少�；谝陨险J(rèn)識(shí),論文以西南山區(qū)一段高達(dá)22m的返包式加筋陡坡高路堤工程為依托,采用大型直剪試驗(yàn)、現(xiàn)場(chǎng)監(jiān)測(cè)、數(shù)值模擬和離心機(jī)模型試驗(yàn)相結(jié)合的方法系統(tǒng)研究了返包式加筋陡坡高路堤的結(jié)構(gòu)荷載狀態(tài)、筋土相互作用特性、穩(wěn)定性影響因素、結(jié)構(gòu)變形破壞模式等關(guān)鍵問題,研究成果可以為類似返包式加筋路堤結(jié)構(gòu)的優(yōu)化設(shè)計(jì)和施工提供理論依據(jù),具有重要的工程應(yīng)用價(jià)值。論文所做工作及取得的主要成果如下:(1)通過粗粒土填料和土工格柵的界面剪切試驗(yàn),揭示了筋土界面相互作用關(guān)系特性。隨著含水量的增加,筋土界面剪切的內(nèi)摩擦角逐漸降低,而粘聚力則先增大后減小;填料中粗顆粒含量與筋土界面剪切的內(nèi)摩擦角和粘聚力均呈正相關(guān)關(guān)系;粗粒土填料加筋可以明顯提高土體的粘聚力,但其內(nèi)摩擦角會(huì)降低。(2)對(duì)依托工程返包式加筋陡坡高路堤進(jìn)行了現(xiàn)場(chǎng)監(jiān)測(cè)試驗(yàn),分析了結(jié)構(gòu)荷載狀態(tài)和加筋體潛在破裂面,主要成果包括:加筋土中的筋材可以有效改善土體中的應(yīng)力分布,減小基底垂直土壓力;加筋體內(nèi)部的應(yīng)力狀態(tài)在后期會(huì)重新調(diào)整而導(dǎo)致格柵應(yīng)變減小;對(duì)于這種柔性返包式加筋體結(jié)構(gòu),由于其坡面變形受限較小,工后很長(zhǎng)一段時(shí)期坡面變形都將處于發(fā)展期。(3)采用FLAC3D建立了不同工況下的數(shù)值計(jì)算模型,探討了返包式加筋陡坡高路堤的加筋機(jī)理、穩(wěn)定性影響因素及變形破壞特征,研究得出:在路基中鋪設(shè)土工格柵能夠顯著降低路基的側(cè)向變形;加筋可以改善路基內(nèi)部剪應(yīng)力的分布;加筋路堤坡度對(duì)土工格柵受拉狀態(tài)有顯著影響。(4)結(jié)合現(xiàn)場(chǎng)監(jiān)測(cè)和數(shù)值模擬的相關(guān)結(jié)果,建立了不同工況下的離心機(jī)模型,針對(duì)返包式加筋路堤結(jié)構(gòu)的穩(wěn)定性影響因素、應(yīng)力應(yīng)變分布特征、變形破壞過程等開展系統(tǒng)研究,進(jìn)一步驗(yàn)證了相關(guān)結(jié)論的可靠性。研究得出:在穩(wěn)定狀態(tài)內(nèi),加筋土結(jié)構(gòu)內(nèi)部的潛在微裂縫并不是沿標(biāo)準(zhǔn)的圓弧、直線或折線發(fā)展,而是受加筋及筋土接觸面的影響呈現(xiàn)出復(fù)雜的分布形式;極限狀態(tài)時(shí),加筋邊坡內(nèi)部潛在破裂面呈圓弧型;直立加筋路堤結(jié)構(gòu)設(shè)計(jì)時(shí),不能簡(jiǎn)單地按照無筋路基的方法僅根據(jù)墻高和填土內(nèi)摩擦角來確定0.3H型破裂面的位置,而應(yīng)考慮加筋的影響并結(jié)合數(shù)值模擬的分析結(jié)果綜合確定最危險(xiǎn)破裂面位置。
[Abstract]:In recent years, with the more and more extensive application of reinforced soil technology, scholars at home and abroad have done a lot of research on the structural characteristics of reinforced soil. Because of the characteristics of rock and soil and the complexity of engineering practice, although some progress has been made, it is still unable to meet the requirements of engineering practice. At present, the research of backpack reinforced structure is mainly focused on single or multi-stage (near) vertical shoulder reinforced earth retaining wall, and its fillers are mostly clay or sandy soil, but the research on reinforced steep slope height embankment structure and gravel soil filler is still rare. Based on the above understanding, based on a 22m backpack reinforced steep slope high embankment project in southwest mountainous area, a large-scale direct shear test is adopted, and field monitoring is carried out. Based on numerical simulation and centrifuge model test, the key problems such as structural load state, interaction between reinforcement and soil, influence factors of stability, structural deformation and failure mode of the embankment with backpack reinforcement and steep slope are systematically studied. The research results can provide a theoretical basis for the optimal design and construction of similar reinforced embankment structure, and have important engineering application value. The main achievements of this paper are as follows: (1) through the interface shear tests of coarse grained soil filler and geogrid, the characteristics of the interaction between reinforcement and soil interface are revealed. With the increase of water content, the internal friction angle of the interfacial shear decreases gradually, while the cohesive force increases first and then decreases, and the content of coarse particles in the filler is positively correlated with the internal friction angle and cohesive force of the interfacial shear of the reinforced soil. The reinforcement of coarse grained soil filler can obviously increase the cohesive force of soil, but its internal friction angle will be reduced. (2) the field monitoring test is carried out on the embankment of steep slope with backpack reinforcement, and the load state of the structure and the potential fracture surface of the reinforced body are analyzed. The main results are as follows: the reinforcement in reinforced soil can effectively improve the stress distribution in the soil and reduce the vertical soil pressure of the base; The stress state inside the stiffened body will be readjusted at the later stage, resulting in the reduction of the grid strain. For this flexible backpack reinforced body structure, the slope deformation will be in the development stage for a long time after construction because of the small limit of slope deformation. (3) the numerical calculation model under different working conditions is established by using FLAC3D. This paper discusses the reinforcement mechanism, stability influence factors and deformation and failure characteristics of backpack reinforced steep slope high embankment. It is concluded that laying geogrid in the subgrade can significantly reduce the lateral deformation of the embankment; Reinforcement can improve the distribution of shear stress in subgrade. The slope of reinforced embankment has a significant effect on the tensile state of geogrid. (4) combined with the related results of field monitoring and numerical simulation, the centrifuge model under different working conditions is established, and the factors affecting the stability of backpack reinforced embankment structure are discussed. The characteristics of stress and strain distribution and the process of deformation and failure are systematically studied, which further verifies the reliability of the relevant conclusions. The results show that the potential micro-cracks in the reinforced soil structure are not developed along the standard arc, straight line or broken line in the stable state, but show complex distribution form due to the influence of the reinforced and reinforced soil interface. In the limit state, the potential fracture surface of reinforced slope is circular. When the vertical reinforced embankment structure is designed, the location of the 0.3H fracture surface can not be determined simply according to the method of unreinforced roadbed only according to the height of the wall and the angle of internal friction of the fill. The influence of reinforcement should be considered and the location of the most dangerous fracture surface should be determined synthetically with the results of numerical simulation.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：U416.12

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本文編號(hào)：2380587