【作者】 张勇；

【导师】 邢立亭；

【作者基本信息】 济南大学 ， 水文学及水资源， 2013， 硕士

【摘要】 在本论文中，以济阳、商河等半干旱地区作为研究区。在了解区域内咸水形成的矿体地质特征和水文地质条件的基础上，研究了咸淡水交替过程中含水层渗透性的变化特征，并分析了影响含水层渗透系数等水文地质参数变化的因素。受气候、地下水动力条件和古沉积环境的影响，咸水主要分布在易干旱的华北、西北以及沿海地带。目前，国内外对海水（滨海咸水）入侵的研究相对成熟，而对大陆盐化咸水的研究相对薄弱。大陆盐化咸水不同于滨海咸水，它是在特定的地质历史条件下形成的。虽然在开发体系下历经长期降水淋滤和人类活动的影响，但是内陆浅层淡水与咸水依然并存，咸淡水过渡带必定会来回地摆动（咸水和淡水互相驱替），同时伴随着复杂的水文地球化学作用和胶体过程，所以这种移动就有可能在咸淡水界面形成垂直于地下水流的低渗透带，而现有的界面移动理论大都是把含水层的渗透性作为常数来处理的，这显然是不科学的。为此，本课题以半干旱地区为研究对象，选取土样和水样，并设计咸淡水交替定水头试验装置，来进行模拟野外咸水区和淡水区相互驱替的过程。通过不同条件下的模拟控制试验，系统地研究咸淡界面粘粒释放、温度等对含水层渗透性变化的影响，这对于半干旱地区咸水入侵的预测和防治都具有非常重要的理论意义和实用价值，这正是本课题所要研究的重点内容，也是本论文的创新所在。通过咸淡水交替动力学试验，将野外调查、室内试验相结合，探讨咸淡水交替过程对含水层渗透性能的影响，可以得出结论如下：（1）含水介质渗透系数与有效孔隙体积之间有密切的关系，有效孔隙体积越大含水介质的渗透系数也越大。在本文试验研究中，含水介质的体积为1645.97cm³，孔隙度为45.47%，孔隙体积为748.46cm³。（2）在咸水穿透土柱过程中，弥散系数为4.88×10^-8m²/s；在淡水驱替咸水过程中，弥散系数为3.12×10^-7m²/s。研究表明：弥散系数与渗透系数的变化有密切联系，渗透系数变化影响弥散系数，渗透系数变化越快弥散系数越大。（3）在咸水驱替淡水阶段，渗透系数会随着渗出液携带大部分粘粒流出土柱而缓慢增大。随着试验的进行，由于粘粒的释放减少，含水介质的渗透系数趋于稳定。已知粘滞系数与温度呈反比关系，粘滞系数会随着试验温度的下降而增大，从而导致含水介质渗透系数减小。然而试验数据显示，渗透系数不降反升，故在咸水驱替淡水阶段，温度的变化对渗透性的影响不起主导作用。（4）当试验进入淡水驱替咸水阶段后，开始时渗透系数从5.0m/d升至5.73m/d，增幅为14.7%。此时流速越大，含水介质中粘粒越容易从孔隙壁上脱落，粘粒的释放量也随之增大。而随着粘粒在含水介质中重新迁移和结合，孔隙介质出现阻塞，最终导致含水介质渗透系数的骤降，降幅为56.2%。在淡水驱替咸水阶段的第21³1天，试验环境温度的降低加速了渗透系数的减小。而随后时间内，渗透系数有升有降，总体上呈现波动上升趋势，最后稳定在5.45m/d。因此，在此阶段，温度的变化对渗透性的影响也不起主导作用。更多还原

【Abstract】 In this article, we take semi-arid area such as Jiyang and Shanghe as the study area. On thebasis of the understanding of salt water which is formed by geological features of ore body andhydrogeological conditions in the study area, we research the variation characteristics ofaquifer permeability in the brackish-water alternate process, and analyzes the influence factorsof hydrogeological parameters such as coefficient of permeability of aquifer. Under theinfluence of climate, groundwater dynamic condition and the ancient sedimentary environment,salt water are mainly distributed in the dry North China, northwest and coastal zone. At present,the research on the invasion of seawater （coastal brackish） is relatively mature for both at homeand abroad, but the study of continental salinization salty water is relatively weak. Continentalsalinization salt water is different from the coastal salty water, which is formed under thecondition of certain geological history. Although shallow inland freshwater is long-term underthe influence of rainfall leaching and human activity in the development system, but which isstill coexist with saltwater. Brackish-water transition zone is bound to swing back and forth（salt water and fresh water displace each other）, which is accompanied by a complexhydrogeochemical action and the colloid process, so this kind of move can form a lowpermeability zone in brackish interface perpendicular to the groundwater flow. While theexisting interface movement theories mostly treate the permeability of the aquifer as constant,which is obviously not scientific.Therefore, this topic take semi-arid area as the research object, selecting soil samples andwater samples, and design the brackish-water alternate constant head test apparatus, to simulatethe mutual displacement process of salt water area and fresh water area in the field. Throughthe simulation control tests under different conditions, we systematically studied the influenceof brackish-water interface clay release, temperature, etc on the changes of permeability ofaquifer, which has very important theoretical significance and practical value for the saltwaterintrusion prediction and prevention in the semi-arid region, which is the main content of thistopic to study, is also the innovation of this paper. Through the brackish-water alternatingdynamic experiment, combining field investigation and laboratory test, we explore the influence of the brackish-water alternate process on the penetrating quality of aquifer, and candraw the conclusion as follows:（1） There is a close relationship between the permeability coefficient and the effectivepore volume of the aqueous media, the bigger the effective pore volume of the aqueous mediais, the greater the permeability coefficient is. In the experimental study of this paper, thevolume of aquifer medium is1645.97cubic centimeter, and porosity is45.47%, and porevolume is748.46cubic centimeter.（2） In the process of salt water through the soil column, the dispersion coefficient is4.88×10^-8m²/s; In the process of fresh water displace salt water, the dispersion coefficient is3.12×10^-7m²/s. Research shows that: the dispersion coefficient is closely related with thechange of the permeability coefficient, and the changes of the permeability coefficient affectthe dispersion coefficient, the faster the permeability coefficient changes, the larger thedispersion coefficient is.（3） In the phase of salt water displace fresh water, the coefficient of permeability increaseslowly along with the exudate which carries most clay particle flowing from pillar. As theexperiment progressed, owing to the release of the clay decreases, the permeability coefficientof aquifer plateaus. Known that viscous coefficient is inversely proportional to the temperature,viscosity coefficient will increase as the test temperature drop, thereby resulting inpermeability coefficient of water-bearing media decreases. However the test data shows thatthe permeability coefficient is up instead of down. So in the phase of salt water displace freshwater, the temperature changes effects on permeability which do not play leading role.（4） When the experiment entered the stage of fresh water displace salt water, at thebeginning, the coefficient of permeability is from5.0to5.73m/d, with the growth of14.7%.When the flow velocity is greater, the clay particle of the aqueous media is easier to fall offfrom the pore wall, meanwhile the release amount of the clay particle also increasesubsequently. As the clay particle transfer and combine again in the aqueous media, the porousmedia blocking, eventually lead to the permeability coefficient of the aqueous media plummetwith a decreasing amplitude of56.2%. In21to31days of the stage of fresh water displace saltwater, the drop of the experiment environment temperature accelerate the decrease of thepermeability coefficient. And then, the permeability coefficient rise and fall alternately, and fluctuate upward trend as a whole, and the steady permeability coefficient is5.45m/d finally.Therefore, at this stage, the temperature changes effects on permeability which also do not playleading role.更多还原