【作者】 陈通；

【导师】 王元战；

【作者基本信息】 天津大学 ， 水利工程， 2019， 硕士

【摘要】 碱渣是氨碱法制碱过程中产生的工业废渣,在海岸地区将碱渣进行填埋作为地基土,即可有效降低工程成本又能解决其堆积占地和环境污染问题。复杂应力条件下碱渣土的力学特性和长期变形特性,是碱渣土工程应用需解决的关键问题。针对天津港原状碱渣土开展了室内基本物理力学性质试验、静力学试验、动力学试验和长期变形试验,以试验所得规律为依据,研究了碱渣土的基本工程特性、静力学剪切特性、动力学特性和长期变形特性,建立了碱渣土在复杂应力条件下的强度及长期变形预测模型。本文的主要工作和结论如下:(1)针对天津港碱渣土开展了一系列常规室内土工实验,分析了碱渣土的基本物理力学性质。发现碱渣土具有含水率高、孔隙比大、密度低、液塑限高、压缩性高、可塑性和渗透性较差的特点。碱渣土属于细粒无机土,按卡萨格兰德塑性图分类可进一步划分为高液限粉土,将碱渣作为地基土进行应用时须考虑其工程性质的特殊性。(2)针对天津港原状碱渣土开展了静力学三轴试验,研究了原状碱渣土在不同固结应力条件下的剪切特性。同时,从Mohr-Coulomb理论出发,通过理论推导建立了一种能够反映土体结构性影响的强度模型。该模型将土体的不排水强度分为摩擦强度和原始结构强度两部分,摩擦强度表征土颗粒间摩擦作用的大小,原始结构强度表征土体天然结构性的强弱。在此基础上,将原状碱渣土试验规律与该模型相结合,建立了能同时考虑固结条件和结构性影响的碱渣土强度模型。(3)针对天津港原状碱渣土开展了动态循环三轴试验,研究了其在不同应力条件下的动力特性,发现双幂函数模型能较好的描述超固结土的循环孔压和累积应变在循环压缩和剪胀作用双重影响下的非单调变化规律。同时,在Yasuhara等效超固结模型的基础上考虑原状土结构性的影响,提出了结构性等效超固结模型。将碱渣土循环孔压模型嵌入结构性等效超固结模型,总结得到了碱渣土的循环后强度模型。(4)针对天津港原状碱渣土开展了长期变形试验,分析了碱渣土在不同应力条件下的一维压缩固结变形。以试验规律为依据,总结得到了适用于碱渣土的一维长期变形预测模型。将一维长期变形预测模型应用于天津港北港路及周边道路工程中,对碱渣地基的长期沉降变形进行了预测。更多还原

【Abstract】 Soda residue(SR)is a kind of industrial wastes produced in the process of soda with the method of ammonia-soda.Applying SR to backfilling not only solves the problem of land occupation and environmental pollution,but also saves material cost for foundation engineering.The mechanical properties and long-term deformation of soda residue soil(SRS)under complex stress conditions are the key point to be solved in the engineering application of SRS.Multiple soil tests were performed on the undisturbed SRS of Tianjin Port.Then,the mechanical properties and long-term deformation of SRS were discussed.In final,the predict models of strength and long-term deformation for SRS based on the results of tests were proposed.The main contents and conclusions of this paper are as follows:(1)Conventional soil tests were performed on the SRS of Tianjin Port.Then,the basic physical and mechanical properties of SRS were analyzed.It is found that SRS is characterized by high water content,large pore ratio,low density,high liquid and plastic limit,high compressibility,poor plasticity and permeability.SRS belongs to fine inorganic soil,and can be further divided into high liquid limit silty according to casagrande plastic map.SRS’s spescial properties should pay attention on When apply it to engineering.(2)Static triaxial compression tests were performed on the undisturbed SRS of Tianjin Port.Then,the shear properties of SRS under different consolidation conditions were discussed.Meanwhile,a structural strength model(SSM)based on Mohr-Coulomb theory was proposed.SSM reflects the influence of soil structure on undrained strength,and divides the undrained strength into two parts: friction strength and original structural strength.Friction strength characterizes the magnitude of friction between soil particles.Original structural strength represents the structural effect on soil strength.On this basis,the SRS strength model was established by combining the test results with SSM.The SRS strength model can effectively predict the undrained strength of undisturbed SRS in Tianjin Port under different consolidation conditions.(3)Dynamic triaxial compression tests were performed on the undisturbed SRS of Tianjin Port.Then,the dynamic properties of SRS under different stress conditions were discussed.It was found that the double-power function model can describe the non-monotonic changes of the cyclic pore pressure and cumulative strain of the overconsolidated soil under the dual effects of cyclic compression and dilatancy.Meanwhile,the structural equivalent overconsolidation model which considering the structural influence was proposed based on Yasuhara equivalent overconsolidation model.The cyclic pore pressure model of SRS was added into the structural equivalent overconsolidation model,and the post-cyclic strength model of SRS was obtained.(4)Long-term deformation tests were performed on the undisturbed SRS of Tianjin Port.The long-term one-dimensional consolidation deformation of SRS under different stress conditions were analyzed.Based on the test results,the predict model of long-term one-dimensional deformation deformation for SRS are established.The predict model of long-term one-dimensional deformation was applied to the road engineering in Tianjin Port,and the long-term settlement of the SR foundation were predicted.更多还原