本文關(guān)鍵詞： 高速公路拓寬工程 泡沫輕質(zhì)土 彈塑性有限元分析 軟土地基 硬殼層效應(yīng) 有限元強(qiáng)度折減 塑性區(qū)貫通　出處：《河北工業(yè)大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：針對(duì)東南沿海地區(qū)軟土地基上的高速公路拓寬工程,通過分析其病害機(jī)理及不協(xié)調(diào)變形的控制手段,結(jié)合目前廣泛推廣采用的輕質(zhì)填料,提出應(yīng)轉(zhuǎn)變處理角度:從提高拓寬路基下軟基的承載力或固結(jié)度轉(zhuǎn)變?yōu)榻档推渖细哺郊雍奢d,以期通過控制拓寬路基填料的性質(zhì)來減小對(duì)軟基的處理強(qiáng)度并合理優(yōu)化擋墻結(jié)構(gòu)。本文以唐津高速擴(kuò)建工程為研究載體,結(jié)合現(xiàn)場(chǎng)對(duì)泡沫輕質(zhì)土拓寬路基的土壓力實(shí)際監(jiān)測(cè)與有限元數(shù)值模擬分析,從以下幾方面進(jìn)行了重點(diǎn)研究:首先,對(duì)泡沫輕質(zhì)土的主要物理力學(xué)指標(biāo)特性及其工程應(yīng)用機(jī)理進(jìn)行總結(jié)分析,并結(jié)合有效應(yīng)力原理及硬殼層效應(yīng)對(duì)軟基固結(jié)沉降的控制措施進(jìn)行原理性探究,且重點(diǎn)研究了泡沫輕質(zhì)土用于軟基上路基拓寬的力學(xué)機(jī)理,明確指出土工合成材料用于板體性輕質(zhì)土拓寬銜接時(shí)應(yīng)著重考慮的因素。其次,從巖土材料產(chǎn)生塑性變形的內(nèi)在機(jī)制出發(fā)研究其區(qū)別于金屬材料的彈塑性理論,并根據(jù)泡沫輕質(zhì)土的力學(xué)特性指出其對(duì)DP理想彈塑性模型的適用性。結(jié)合路基拓寬的施工階段影響及輕質(zhì)土本身的施工特點(diǎn),利用舊路基及地基自重荷載產(chǎn)生的初應(yīng)力場(chǎng)施加及舊路邊坡開挖、輕質(zhì)土分層澆筑的單元生死技術(shù),對(duì)輕質(zhì)土拓寬路基在施工過程中及不同拓寬斷面尺寸下的應(yīng)力響應(yīng)進(jìn)行非線性結(jié)構(gòu)分析,提出了輕質(zhì)土板體在澆筑層間及基底處類似于剛性基礎(chǔ)的傳力機(jī)制,并結(jié)合硬殼層效應(yīng)及輕質(zhì)土荷載分布特點(diǎn)對(duì)拓寬路基不同位置處的位移發(fā)展趨勢(shì)進(jìn)行探索,以明確輕質(zhì)土拓寬路基的受力薄弱區(qū)及位移發(fā)展集中區(qū)。最后,通過強(qiáng)度折減原理,對(duì)輕質(zhì)土拓寬路基的整體穩(wěn)定性進(jìn)行分析,從輕質(zhì)土的材料參數(shù)、軟基的抗剪強(qiáng)度、硬殼層三個(gè)因素探究其對(duì)拓寬后路基整體的塑性區(qū)貫通、側(cè)向位移發(fā)展的影響,并重點(diǎn)對(duì)比研究了高窄型與低寬型拓寬路基的塑性區(qū)形成特點(diǎn)及失穩(wěn)破壞機(jī)理,從而指導(dǎo)拓寬時(shí)輕質(zhì)土材料設(shè)計(jì)參數(shù)的調(diào)整、土工材料銜接處理的重要位置確定及軟基的針對(duì)性加固。
[Abstract]:Aiming at the expressway widening project on soft soil foundation in southeast coastal area, through analyzing the disease mechanism and the control means of uncoordinated deformation, combining with the light packing widely used at present, It is proposed that the angle of treatment should be changed: from increasing the bearing capacity or consolidation degree of soft foundation under widening roadbed to reducing the additional load on top of it, In order to reduce the treatment strength of soft foundation and optimize the structure of retaining wall by controlling the property of widening the filling of roadbed, this paper takes Tangjin high-speed expansion project as the research carrier, Combined with the field monitoring and finite element numerical simulation analysis of the earth pressure of the foamed lightweight soil widening roadbed, the following aspects are emphatically studied: first of all, The main physical and mechanical properties of foamed light soil and its engineering application mechanism are summarized and analyzed, and the control measures of consolidation settlement of soft foundation are studied by combining the effective stress principle and the effect of hard shell layer. The mechanical mechanism of foam lightweight soil used for roadbed widening on soft foundation is emphatically studied, and the factors that should be considered when geosynthetics are used in widening of plate lightweight soil are pointed out. Secondly, Based on the inherent mechanism of plastic deformation of geotechnical materials, the elastic-plastic theory, which is different from metal materials, is studied. According to the mechanical characteristics of foamed lightweight soil, the applicability of this model to DP ideal elastoplastic model is pointed out, which is combined with the influence of roadbed widening in construction stage and the construction characteristics of lightweight soil itself. The unit life and death technique is used to apply the initial stress field caused by the old roadbed and the deadweight load of the foundation, and excavate the slope of the old road, and the light-weight soil is poured into layers. The nonlinear structural analysis of the stress response of lightweight soil widening roadbed during construction and under different widening section sizes is carried out, and a force transfer mechanism similar to that of rigid foundation is put forward, which is similar to that of rigid foundation. Combined with the effect of hard shell and the characteristics of load distribution of lightweight soil, the development trend of displacement at different positions of widening roadbed is explored, in order to make clear the weak area of stress and the concentrated area of displacement development in widening roadbed of light soil. Finally, through the principle of strength reduction, Based on the analysis of the overall stability of the light soil widening roadbed, the effects of the material parameters of the light soil, the shear strength of the soft foundation and the hard shell layer on the overall plastic zone and lateral displacement development of the roadbed after widening are discussed. The forming characteristics of plastic zone and failure mechanism of high narrow and low width widening roadbed are compared and studied so as to guide the adjustment of design parameters of lightweight soil material. The important position of joint treatment of geotechnical materials and the targeted reinforcement of soft foundation are determined.
【學(xué)位授予單位】：河北工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：U416.1

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