软土高填方路基后处理技术及工程应用研究

【作者】 张浩华；

【导师】 郭院成；

【作者基本信息】 郑州大学 ， 结构工程， 2004， 硕士

【摘要】 软土高填方路基的后期沉降变形较大，且稳定时间长，常使高速公路在投入使用若干年后产生显著的沉降变形，影响正常使用。无砂混凝土小桩后处理技术具有排水固结、胶结、竖向增强置换等综合作用，适用于处理公路路基工程中可能遭遇的饱和软土、粉质粘土、粘性土及人工填土中的素填土和含少量大块碎屑的杂填土地基。可用于填土前的处理，也可用于填土后处理，其后处理方法独特是其它处理方法难以做到的。其在软土路基工程中的成功应用为高速公路软基及不良地基和桥台填方区处理技术提供了一条新的途径，有着极其重大的技术经济价值。 本文依据应力路径的基本概念，以及无砂混凝土小桩在路基后处理过程中的施工技术特点，分析研究了无砂混凝土小桩复合地基技术后处理软土路基的机理，并据此分析了路基下土样在路基碾压施工过程中的应力路径以及后处理过程的应力路径特点，初步建立了依据应力路径分析方法的复合地基基于承载力控制条件的设计计算方法，实现了与地基处理技术设计方法的对接，便于工程应用。 文中建议无砂混凝土小桩后处理路基的设计计算先根据复合土层的K_f′线，反求处理后复合土层的等效内摩擦角φ′，然后再由《建筑地基基础设计规范》中根据土的抗剪强度指标确定地基承载力特征值的计算公式确定复合地基的承载力设计要求，并考虑不同土质结构的内部孔隙结构、天然含水量以及灌注浆液水灰比等因素，在应力复合式公式中引入相应的调整系数计算复合地基承载力。 本文还通过无砂混凝土小桩复合地基在高速公路高填方路基地质条件下的单桩和三桩承台试验研究，证明了多桩复合地基的工作状态与单桩载荷板试验的类似性和工程可参考价值，验证了无砂混凝土小桩复合地基处理软土高填方路基承载力和变形性能的有效性。更多还原

【Abstract】 The post-processing technique of small non-sand pile possessed synthetical function such as consolidation. cementation. swell replacement in vertical and so on, which apply to treat saturated weak soil. powdery clay. clay. simple-filling and mixed-filling foundation which were encountered in the highway bed engineering. The post-processing technique not only apply to treat bed before filling, but also apply to treat bed after filling, the superiority of the post-processing technique was not possessed by other treatment technique. The success of applications for the post-processing technique in the highway engineering provide a new approach for the treatment of highway soft-foundation and bridge head filling, which have great importance for technique and economy.The analysis and study of mechanism for soft-foundation post-processing with small non-sand concrete pile is completed, according to the basic conception of stress-path and the characteristic of technique in the course of construction of small non-sand concrete pile, on the basis of this, the stress-path in the course of construction and the characteristic of the stress-path in the post-processing; By the analysis of stress-path, the method of design for composite foundation on the basis of control condition of carrying capacity is established, which realize the consistence with the technique of ground treatment of buildings and convenience for application of engineering.The design process of composite foundation with small non-sand concrete pileinclude following step: First, according to the kf line of composite foundation,p -equivalent friction angle of composite soil was gained; Second, according tocalculative formula in the code for design of building foundation, the carrying capacity eigenvalue was received. At the resent time, stress formula often apply to the calculation of carrying capacity, certainly, the introduction of relevant parameter is reasonable according to the pore structure. containing water of soil and water-cement ratio of grouting.The examination research of composite foundation with small non-sand concrete pile prove the similarity and reference value of composite foundation with simple-pile and multi-pile, also, the examination testify the efficiency of carrying capacity and settlement of composite foundation with small non-sand concrete pile for highway thick filling area.更多还原