加筋地基承载力增强机理与设计应用研究

发布时间：2018-01-09 03:23

本文关键词：加筋地基承载力增强机理与设计应用研究　出处：《重庆大学》2013年博士论文　论文类型：学位论文

【摘要】：加筋土技术以其显著的技术经济效益，越来越广泛的应用在公路、铁道、市政、建筑等领域。加筋地基能有效的提高地基承载力和变形协调能力，减小沉降和不均匀沉降，但由于加筋地基筋土作用机理和承载力增强原理研究不足，理论研究远远滞后于工程实践，使加筋地基设计技术缺乏理论支撑，设计方法目前仍处于经验阶段，严重的制约其推广使用。本文在前人研究的基础上，在教育部长江学者和创新团队发展计划创新团队“山区岩土工程”（IRT1045）项目的资助下，采用室内模型试验、理论研究和数值分析等手段，全面研究了加筋地基土应力和筋带应力变化规律、筋带影响区滑移线形态特征、承载力极限值，建立了加筋地基承载力增量设计方法，为加筋地基设计提供理论指导。进行的主要研究工作如下： ①通过模型试验重点研究了加筋地基破坏区内筋带应力和地基应力，对比分析加筋地基和无筋地基承载力和沉降变形特征，揭示了地基内主动状态区、过渡区、被动状态区和被动区外锚固段筋带应力变化规律、筋带影响区内土应力变化规律，分析了筋带对地基中对土应力的作用。 ②根据筋带对地基土的作用规律，建立了加筋地基应力计算模型，，分析了地基内主动状态区、过渡区、被动状态区内土体剪应力变化，结合Mohr-Coulomb原理，采用应力分析法和几何求解法获得了应力解；采用数值模拟揭示了地基加筋后各区筋带应力和土应力变化规律。 ③通过对无筋土地基滑移线理论的分析，结合筋土作用机理，建立了滑移线计算模型和滑移线方程，根据加筋地基各区边界条件，获得了筋带影响区内的滑移线解和应力解，并揭示了筋带在加筋地基中的形成了水平高应力带。 ④根据加筋地基滑移线分析成果，构建了加筋地基静力场和机动场；运用上限定理，求解筋带影响区的能量耗散率，分别建立纯粘土加筋地基和一般土加筋地基的虚功率方程，求解加筋地基承载力上限值；分别建立纯粘土加筋地基和一般土加筋地基的静力场方程，运用下限定理，求解加筋地基承载力下限值；通过分析上限值和下限值的差异，确定地基承载力极限值，并分析纯粘土加筋地基和一般土加筋地基极限值的关系。 ⑤在现有加筋地基承载力设计方法的基础上，根据加筋地基承载力极限分析理论，运用上限值和下限值求解加筋地基极限承载力增量，应用强度折剪系数和筋带置换系数，求解加筋地基承载力增量设计值和筋带强度设计值，建立加筋地基承载力增量设计法。并以天江鼎城Ⅰ期雅园小区填土地基为例，将极限分析法设计的加筋地基承载力增量与实际静载试验成果进行对比，验证承载力增量极限分析法的可靠性。
[Abstract]:Reinforced soil technology with its remarkable technical and economic benefits, more and more widely used in highway, railway, municipal, construction and other fields. The reinforced foundation can effectively improve the foundation bearing capacity and deformation coordination capacity, reducing settlement and uneven settlement, but due to insufficient research in principle of reinforcement mechanism and bearing capacity of reinforced foundation reinforced soil, theoretical study is far behind engineering practice, the design technology of reinforced foundation lack of theoretical support, the design method is still in the stage of experience, seriously restricting its application. Based on the previous research, the Ministry of education Changjiang Scholars and innovative research team plan innovation team "development in the mountainous areas of geotechnical engineering" (IRT1045) project funded by the indoor model test, theory research and numerical analysis, a comprehensive study of the reinforced soil stress and reinforcement stress variation affected zone of slip line shape band Based on the characteristics and ultimate bearing capacity, the incremental design method of reinforced foundation is established, which provides theoretical guidance for the design of reinforced foundation.
Through the model test on reinforced foundation failure zone reinforcement stress and foundation, comparative analysis of reinforced foundation and reinforced foundation bearing capacity and deformation characteristics, reveals the foundation of active zone, transition zone, passive and passive zones outside the anchorage reinforcement stress variation that band in the influence area of soil stress variation analysis of reinforcement on stress of soil foundation in the role.
According to the rules of the foundation soil reinforcement, a stress calculation model of reinforced foundation, analyzes the foundation of active zone, transition zone, passive area soil shear stress change, combined with the principle of the Mohr-Coulomb, using the stress analysis method and geometry method to obtain the stress solution; numerical simulation reveals the foundation reinforced District reinforcement stress and soil stress variation.
Through the analysis of non reinforced foundation slip line theory, combined with the soil reinforcement mechanism, calculation model and slip line equation of slip line is established according to the boundary condition of reinforced foundation, the reinforcement effect of slip line in solution and the solution of stress, and reveals the reinforcement in the reinforced foundation the formation of the high level of stress.
According to the analysis results of reinforced foundation slip line, construction of reinforced foundation static field and motor field; using upper bound theorem, the energy dissipation rate for impact zone band, established a virtual power equation of pure clay reinforced foundation and reinforced the general soil foundation, solve the reinforced foundation bearing capacity limit are established; the static field equations of pure clay reinforced foundation and reinforced the general soil foundation, using the lower bound theorem for reinforcement of foundation bearing capacity limit; through the analysis of the upper limit and the lower limit value differences, to determine the bearing capacity limit, and analyze the relationship between the pure clay reinforced foundation and soil foundation reinforced with a limit value.
The basic design method of bearing in existing reinforced foundation, according to the theoretical analysis of bearing capacity limit of reinforced foundation, the upper limit and lower limit increment of bearing capacity for solving the limit of reinforced foundation, application of strength reduction factor and reinforcement coefficient of displacement, solving the reinforced foundation to increase the design value and the reinforcement strength design value of bearing the force bearing capacity, establish incremental design method of reinforced foundation. And the day Jiang Dingcheng stage I Nga District fill foundation as an example, the design method of limit analysis of reinforced foundation bearing capacity and the actual incremental static loading test results were compared, the reliability analysis method to increase the ultimate bearing capacity verification.

【学位授予单位】：重庆大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU470

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