【作者】 徐望国；

【导师】 张家生；

【作者基本信息】 中南大学 ， 道路与铁道工程， 2010， 博士

【摘要】 依托湖南省张桑公路工程,以加筋强风化软岩粗粒土路基填料为研究对象,从研究强风化软岩填料基本物理力学性质入手,采用国内先进的大三轴仪进行固结不排水和固结排水剪切试验；通过现场试验,开展加筋强风化软岩路堤填筑技术研究；基于试验成果,利用有限差分法分析高填路堤分层填筑过程中在自重作用下的变形和力学性状以及加筋、雨水入渗对高填土路堤变形和力学性状的影响。主要研究成果有：1.通过扫描电镜(SEM)分析、X光衍射试验及化学分析研究软岩的微观结构及成分构成；用洒水和吹晒循环试验,模拟软岩在大气中的自然崩解过程,分析崩解矿物颗粒分布特征；同时对软岩的压实特性、水稳特性及路用工程力学特性等问题进行研究。从不同角度揭示了强风化软岩填料的工程性质。2.采用国内先进的大型三轴试验仪,进行固结不排水和固结排水条件下的大试样的加筋粗粒土三轴试验。在大量大三轴试验的基础上,对固结不排水和固结排水条件下加筋强风化软岩粗粒土路堤填料的强度变形特性进行深入研究。试验结果表明：加筋填料的应力-应变关系表现为应变硬化型；轴向应变较小(εa<1%)时,加筋效果表现得不明显,随着轴向应变的逐渐增大,加筋作用逐渐发挥；加筋填料的孔隙水压力均高于素填料,随着加筋层数的增加均有不同程度的提高；加筋效果系数均大于1.0,一层加筋填料加筋效果系数1.09～1.21,二层加筋填料加筋效果系数1.30～1.71,三层加筋填料加筋效果系数1.31～1.72；准粘聚力原理仍适用于加筋强风化软岩填料,加筋前后填料的内摩擦角φ值基本相同,加筋填料强度的提高主要体现在增大了填料的粘聚力；加筋填料的本构关系可以采用邓肯-张E-v模型描述。3.结合工程实际,开展加筋强风化软岩路堤填筑技术研究,提出了具有很强针对性及工程应用价值的施工控制技术及质量检测方法,为加筋强风化软岩粗粒土路基填料路堤的设计、施工提供了科学参考。4.根据地形地貌条件、地质结构特征,建立三维地质结构分析模型；采用VC++6.0编程进行软件二次开发,将邓肯-张E-v模型嵌入FLAC数值分析软件中,模拟分析高填路堤分层填筑过程中在自重作用下的变形和力学性状以及加筋对张桑二级公路高填土路堤变形和力学性状的影响。5.分析降雨入渗机理,结合张桑公路工程实践,研究常用路堤降雨入渗深度计算公式的适应性。计算实例表明Pradel & Raad公式比较接近实际情况。同时,分析降雨入渗对土体强度的影响,并采用FLAC强度折减法模拟分析雨水入渗对高填路堤附加变形及稳定性的影响。更多还原

【Abstract】 With the support of Zhang-sang highway which is going to be built, this paper studies on the main engineering properties of reinforced badly weathered soft rock granular soil embankment fillings. Physical and mechanics tests are conducted to study the physical mechanics properties of badly weathered soft rock fillings. The large-scale consolidated-drained and unconsolidated-undrained triaxial tests are carried out on reinforced soft rock granular soil fillings. Constructing technology on geosynthetic badly weathered soft rock embankment are studied by field tests. Based on experimental data, Finite difference method are used to analyze deformation and mechanical behavior of high filled embankment under dead weight in layer filling process with considering reinforcement and rain penetration. Main achievements are concluded as follows:1. The microstructure and composition of badly weathered soft rock fillings are researched by means of SEM, x-ray diffraction and chemical analysis. The natural collapsing process of soft rocks at the atmosphere is simulated through tests of cyclic watering, blowing and sunning, and the grading of soft rock crumbling pellets is also investigated. At the same time, compaction property, water-stable ability and mechanical characteristics for road are also studied. The engineering properties of badly weathered soft rock fillings are discussed from various aspects.2. In order to study the deformation properties and geotextile reinforcement effect of the geotextile soft rock granular soil fillings, the large scale triaxial tests were carried out. The tests showed the hardening strain in deformation properties of geotextile-soil samples. There exists puny geotextile reinforcement effect while axial strain is less than 1%, and the geotextile reinforcement effect showed more clearly with the increase of axial strain. The pore water pressure of geotextile-soil samples is higher than that of pure granular soil samples, and the pore water pressure of geotextile-soil increases with the geotextile layers. The geotextile reinforced effect coefficients were lager than 1.0, with 1.09～1.21 for one layer geotextile,1.30～1.71 for one layer geotextile,1.31～1.72 for one layer geotextile. The mechanism of geotextile soft rock granular soil fillings still obeys the principle of "quasi- cohesion". Its inner friction angelφnearly kept changeless, while its cohesion force c increases with the increase of geotextile layers. The constitutive relations of reinforced fillings may be described in Ducan-chang E-v model, and the parameters of Duncan-Chang model for geotextile-soil were identified from the tests.3. With the practical examples in engineering, the filling technology of geosynthetic badly weathered soft rock granular soil fillings embankments is thoroughly studied. Directed and engineering-valuable construction control technology and quality test method were obtained, which can be scientific references in the design and constructions of geosynthetic badly weathered soft rock granular soil fillings embankments.4. In accordance with topography and geologic framework features on site of Zhang-sang highway project, three dimensions geologic structure analysis model is set up. The computational procedure is developed by editing program with VC++6.0 Language, and Ducan-chang E-v model is embedded into the FLAC numerical simulating software which is used to analyze deformation and mechanical behavior of high filled embankment under dead weight in layer filling process.5. Based on the infiltration mechanism and engineering practice, the commonly used infiltration depth calculation formula for road embankments is analyzed, and practice application suggested that the Pradel & Raad formula is adaptable for calculating the infiltration depth in embankment. Taking in to account decrease in the strength for rain penetration, FLAC strength reduction method is used for analyzing the influence of rain penetration on additional settlement and stability of high filled embankments.更多还原