【作者】 张志红；

【导师】 赵成刚； 李涛；

【作者基本信息】 北京交通大学 ， 岩土工程， 2007， 博士

【摘要】 研究湖泊疏浚底泥中的污染物在底泥堆场下部天然粘土防渗层中的渗透运移规律以及粘土层对污染物的阻隔与防渗效果对防止二次污染具有非常重要的意义。本论文在将固结理论与污染物运移理论相结合的基础上，建立了污染物在变形多孔介质中的运移模型。以国家“十五”863重大科技专项所属课题“太湖水污染控制与水体修复技术及工程示范”研究项目为依托，论文针对太湖周边地区存在丰富的粘土层这一地层条件，开展了底泥堆场防渗粘土层中污染物的运移与阻隔特性的研究工作，取得的主要研究成果如下：1、利用自制的试验设备—双联式三轴渗透仪，针对无锡雪浪堆场底部淤泥质粉质粘土层土样，在室内进行了大量全面系统的渗透、静态吸附和动态土柱试验，试验中考虑了固结变形对污染物在土柱中渗透运移的影响。通过渗透试验确定了氨氮污染物在土样中的渗透系数；根据静态吸附试验计算出了土样对氨氮的吸附系数，并由动态土柱试验测定了氨氮在土样中的扩散系数，根据试验结果得知堆场地基土层和围堰土层对底泥中的氨氮污染物具有良好的阻隔防渗效果，同时也揭示了污染物在粘土中的一些运移转化规律。2、在将比奥固结理论和污染物运移理论结合的基础上，提出了污染物在粘土防渗层中运移的一维数学模型，该模型的最大特点是考虑了土体受力变形对污染物运移的影响。3、经过合理简化，得到了不考虑污染源浓度衰减与考虑污染源浓度衰减两种情况下所建运移模型的解析解；并对底泥中所含氨氮污染物在堆场下卧的淤泥质粉质粘土层中的运移进行了数值模拟计算，同时还对氨氮浓度在土层中的时空分布进行了预测。根据模型计算结果、试验结果与调研资料，对无锡雪浪堆场的防渗隔污能力进行了评价。结果表明堆场的围堰和地基土层对太湖疏浚底泥中的污染物已具备了足够的阻隔能力，在堆场的使用年限内不会对周围环境造成二次污染。4、因为实际天然防渗层中以成层土居多，故推导污染物在成层土中的运移模型具有非常重要的工程价值和现实意义。根据多层地基的固结模型，给出了污染物在成层弹性地基中运移模型。利用所建模型计算了太湖疏浚底泥中含有的主要污染物-氨氮在双层地基中运移时浓度随时间和深度的变化。5、通过物质坐标系下的大变形固结方程的近似解，给出了考虑土体固结大变形的污染物运移模型的表达式。更多还原

【Abstract】 The research on the infiltration and transport of contaminant in clay impermeable layer and obstruction of contaminant to clay layer is very important to prevent secondary pollution. In this paper the transport model of contaminant is set up in deformed porous medium on the base of combing the consolidation theory with contaminant transport theory. Relying on the project of state 863 important special problem, the research on transport and obstruction of contaminant in clay layer in sludge site is conducted using the abundant clay layer in peripheral area. The main research result is shown in the following:1 Using the duplex triaxial permeability testing machine and the muddy and silty clay of Xuelang heap site in Wuxi, a great deal of indoor tests on infiltration and static adsorption and dynamic soil column have been done, the effect of consolidation deformation on infiltration and transport of contaminant in soil column in tests is considered. The permeability coefficient of ammonia nitrogen in soil sample is found through infiltration test, the adsorption coefficient of soil sample to ammonia nitrogen is measured by static adsorption test, and the diffusion coefficient of soil sample to ammonia nitrogen is also measured by dynamic soil column test. Through the infiltration test results it can be gained that the heap site soil layer and coffered soil layer have good obstruction effect, and the transport rule of contaminant is presented in deformed clay layer.2 On the base of combing the Biot consolidation theory with contaminant transport theory the one-dimensional mathematic model of contaminant in clay layer is put forward. The greatest feature of model is considering the effect of soil deformation on contaminant transport through introducing the contaminant chroma adsorbed the solid grain to the contaminant transport model.3 The analytic solutions of transport model are gained through rational predigestion, they include considering the decaying of pollutant source and without considering the decaying of pollutant source. The numerical calculation on transport of ammonia nitrogen in muddy and silty clay layer is done, and the space-time distributing of ammonia nitrogen chroma in soil layer is predicted. The impermeable ability of heap site is estimated according to the calculated result of model and test result and investigated data. The results have shown the cofferdam and ground soil layer has enough ability to obstruct the contaminant of dredged sludge and can’t produce secondary pollution in the fixed number of year of heap site.4, The transport model of contaminant in layered elastic ground is found according to the consolidation model of multilayer ground. Using the transport model the change of ammonia nitrogen chroma with the time and depth is calculated in the double layer. Because the layered soil is abundant in actual impermeable layer, the transport model of contaminant in layered soil has important project value and realistic meaning.5 The expression of transport model of contaminant considering soil consolidation large deformation is put forward according to the approximate solution of large deformation consolidation equation in material coordinate.更多还原