【作者】 薛强；

【导师】 梁冰；

【作者基本信息】 辽宁工程技术大学 ， 工程力学， 2004， 博士

【摘要】 石油污染物造成的环境污染问题已引起了国内外水文地质学者和环境学者的广大关注，并成为地下环境污染控制研究中的热点和焦点问题。石油污染物对地下环境系统的污染是一个极其复杂的动力学过程，由于研究所涉及的问题是多学科的交叉点，加之问题的复杂性，所以，以往的研究多侧重于实验机理和污染治理方面的研究，很少从多相流流体理论和溶质运移动力学理论角度出发，对污染物质在土壤－水环境系统迁移转化的动力学行为进行定量化研究。为此，本文基于前人研究成果基础之上，借助相关学科的研究成果，深入研究了石油污染物在地下环境系统中迁移转化的规律、时空分布特征、控制多相流系统的本构模型以及污染去污过程滑逸耦合模型等方面的问题，从理论上建立油水气多相流动的渗流场和有机污染物迁移转化的浓度场耦合作用条件下动力学数学模型，并给出了数值解法，实现耦合系统的软件化，并以此为工具，来预测预报有机污染迁移转化的动态及过程，对于更科学地、更有效地控制石油泄漏带来的环境污染问题具有更重要的理论意义和实际意义。本论文的研究摘要有以下四个方面：采用室内土柱实验，开展了石油污染物在不同质地土壤介质中驱替实验以及含油废水淋滤物理模拟实验研究，揭示了石油污染物在土壤中淋滤深度与土壤质地之间有着密切的关系，在砂性土壤的石油污染物截留率为45.8%，而粘性土壤中其截留率为76.4%，这对于定量化研究石油污染物在土壤水环境系统中迁移转化规律提供基础资料。油气水多相流体系中毛细压力－饱和度－相对渗透率之间关系曲线的确定是研究石油污染物在地下环境系统中驱替机理和数值模型的关键性技术。本文应用渗流力学和参数反演最优化理论，给出了控制多相流系统之间的参数本构模型，采用约束变尺度方法对模型参数进行反演辨识，得出了待求参数的最优估计值。通过计算结果可以得出，采用本文数值方法求得的数值优化结果与实验测试结果吻合较好，表明文中所建立的数值方法是可行和可靠的，有效地克服了数值结果对参数初值的敏感性问题。在综合考虑有石油污染物在地下环境体系中扩散、吸附解吸、界面间分配以及微生物降解等化学反应条件下，建立了有机污染物在多孔介质迁移转化的多组分多相渗流动力学模型，并采用特征有限差分方法和隐式压力显式饱和度方法对耦合模型进行数值离散，编制了相应的计算软件（MCTS1.0）；利用该软件对石油污染物在地下环境系统中运移机制进行定量化研究，研究结果表明：石油污染物在地表泄漏以后，将在重力和毛细力的作用下，产生水平位移和垂直位移，但其总体趋势为向下迁移。当污染物迁移到地下毛细管区后，其向下的运动将整体受到毛细张力的阻碍，污染<WP=5>物要想进入毛细饱和带必须克服油－水界面的进气压力，这时污染物在毛细饱和带顶部聚集以期获取压力，同时将产生以水平方向为主的迁移，最终随着污染物的压力超过其进气压力，导致污染物进入毛细饱和带，到达地下水位，此时污染物将沿地下水水流方向横向扩展开来，并在地下水水位上形成一个透镜体,这为定量研究石油污染物在地下环境系统中分配与归宿提供了可靠的理论依据，同时为土壤环境质量评价及污染预测、预报与污染防治提供科学的根据与途径。考虑气体滑脱效应条件下，提出了挥发性有机污染物去污过程的滑逸耦合模型，并给出了耦合动力学模型的有限差分格式。采用所建立的数值模型对抽排状态下有机污染物的释放过程进行数值模拟，并对不同质地的土壤和土壤含水率进行灵敏度分析。同时，对于挥发性污染物横向迁移问题采用摄动法及积分变换法进行了解析求解，定量研究填埋气体的压力分布特征。数值模拟结果表明：滑脱效应对污染气体释放过程有较大影响，抽气量越大，其差别越明显，在连续抽排条件下污染气体的分布范围和浓度均明显减小，抽排前期对气体浓度分布和气体产量有较大的影响，并且所得到的滑脱解与实测数值吻合较好，因此，研究挥发性污染气体释放时不能忽略滑脱效应。这不仅对于污染气体抽排系统工程设计及环境预测评价提供基础理论依据，而且可为油气田开发过程中污染的治理与恢复具有重要的参考价值。本文的研究成果不仅对于定量化研究有机污染物在地下环境系统中迁移归宿、环境质量评价及污染预测、预报与污染防治提供科学的理论根据与途径，而且对于完善和丰富地下水动力学、溶质运移动力学以及多孔介质渗流力学等理论做出贡献。更多还原

【Abstract】 The environmental problems caused by petroleum pollutant have been studied by researchers in fields of hydrology and geology, environmental science in home and abroad, and they have become the focuses of research on subsurface environmental pollution control. Petroleum pollutant to subsurface environment is a very complex kinetic progress and because the problems considered are the multi-crossed disciplines and they are very complex, experimental mechanism and pollution prevention were often focused on in studies, and it is seldom to study the dynamic behavior quantitatively of pollutant transport and migration in subsurface environment based on the theories of multiphase flow and solute transport dynamics. Therefore, based on the study results before and using the research results in relative science, Petroleum pollutant transport and migration laws, its temporal and spatial distribution, the constitutive model controlling multiphase flow and the slippage and release coupled model in groundwater environment and so on are deeply discussed. And the coupled dynamic mathematical model of oil-water-gas multiphase flow seepage field and organic pollutant transport and migration concentration field is established theoretically, and the numerical method is given. In addition, the simulation code is developed, and the numerical model is used to predict the temporal and spatial distribution of organic pollutant concentration under the conditions of multi-field coupling effect. It has important theoretical significance and practical value for preventing pollution caused by oil spills more scientificly and effectively. The abstract of this paper includes the following four points:1. By the laboratory column tests, the petroleum pollutant displacement experiment and the physical modeling experiment of waste water with oil in different soils are designed and developed, the petroleum pollutant retention in sandy soil is 45.8%, and it is 76.4% in clays. It provides scientific basis for the quantitative studies of petroleum pollutant transport and migration in subsurface environment. 2. Determination of capillary pressure-saturation-relative permeability relationship curve of oil-water-air flow system is the key technique in studies of petroleum pollutant displacement theories and numerical model in groundwater environment. The parameters’ constitutive model controlling multiphase flow is given based on seepage mechanics and parameter inversion optimization theory. And the optimized estimator is obtained by adopting <WP=7>constrained variable metric method to inverse the parameters. It shows that the optimized values by the numerical method in this paper is in good agreement with the experimental data, and the comparison analysis validates the reliability and practicability of numerical model, which solves the sensitivity of the values to the initial conditions.3. On the conditions of considering comprehensively the diffusion, absorption/desorption, distribution between phase surface and the biodegradation progresses, the multiphase and multicomponent model of the petroleum pollutant transport and migration has been established, and the characteristic finite difference method and implicit pressure explicit saturation method are adopted to discrete the coupled model. Moreover, the code （MCTS1.0）is developed to analyze petroleum pollutant transport and migration mechanism in different porous media. The results show after petroleum is leaked out on the earth surface, it will have displacement vertically and horizontally under the pressure of weight and capillary pressure, but the direction of its transport and migration is vertical as a whole. When the pollutant arrives the capillary saturated zone, the vertical movement is blocked by the capillary tension. The pollutant must overcome the oil-water surface inlet air pressure before it entering the capillary zone, and pollutant accumulates on the top of capillary saturated zone to obtain the necessary pressure, and meanwhile it transport and migrate horizontally. In the end更多还原