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997.
为了探讨在再生水地表回灌条件下,再生水对地下水中氨素和主要盐分浓度变化的影响,选取现实存在的清河再生水湿地公园为例,以氨氮、Cl-离子为主要研究对象,利用Hydrus-1D溶质运移模型和Modflow、MT3DMSD耦合地下水模型,模拟了再生水长期利用后的地下水氨氮和Cl-指标变化情况。研究结果显示,再生水到达包气带底部时,水中氮氨、Cl-离子含量高于研究区潜水地下水中的相应指标含量,氨氮超出地下水质量Ⅲ类标准。预测5~20年后,潜水中氨氮超标面积不断扩展,20年后将达14km2,氨氮超标垂向延伸至第一层弱透水层;Cl-离子在潜水中不超标,但在湿地公园周边浓度有所增加。湿地公园再生水的长期地表回灌将给当地地下水质量带来负面影响。 相似文献
998.
塔里木陆块西北缘萨热克砂岩型铜矿床构造演化、流体演化与成矿之间具有密切关系,处于一个统一系统中。矿床成岩期方解石中包裹体水的δD值为-65.3‰~-99.2‰,改造成矿期石英包裹体水的δD值为-77.7‰~-96.3‰,成岩成矿期成矿流体δ~(18)OH_2O变化范围为-3.22‰~1.84‰,改造成矿期成矿流体δ~(18)OH_2O变化范围为-4.26‰~5.14‰,指示萨热克铜矿成岩期、改造期成矿流体主要为中生代大气降水及其经水岩作用而成的盆地卤水。矿石中辉铜矿δ~(34)S值为-24.7‰~-15.4‰,指示硫主要源自硫酸盐细菌与有机质还原,部分源于有机硫。构造与成矿流体演化对砂岩铜矿成矿起关键制约作用。盆地发展早期强烈的抬升运动使盆地周缘基底与古生界剥蚀,为富铜矿源层的形成提供了丰富物源,至晚侏罗世盆地发展晚期,长期演化积聚的巨量含矿流体在库孜贡苏组砾岩胶结物及裂隙中富集,在萨热克巴依盆地内形成具有经济意义的砂岩型铜矿床。 相似文献
999.
Qingchao Li Yuanfang Cheng Qiang Li Ubedullah Ansari Yuwen Liu Chuanliang Yan Chuang Lei 《Arabian Journal of Geosciences》2018,11(12):325
Natural gas hydrate is widely distributed all over the world and may be a potential resource in the near future, whereas hydrate dissociation during the development affects wellbore stability and drilling safety. However, the present modeling of hydrate reservoir parameters ignored the influence of effective stress and only considered the hydrate saturation. In this paper, a series of stress sensitivity experiments for the unconsolidated sandstone were carried out, and the influence of mean effective stress on physical parameters was obtained; a comprehensive model for the physical parameters of hydrate reservoir was developed subsequently. With the help of ABAQUS finite element software, the established comprehensive model was verified by the use of the wellbore stability numerical model of hydrate reservoir. The verification results show that ignoring the effect of mean effective stress on the parameters of hydrate formation aggravates the invasion of drilling fluid into the hydrate formation. Besides, ignoring the stress sensitivity of reservoir physical parameters will underestimate the wellbore instability during hydrate drilling, which will be a threat to the safety of gas hydrate drilling. At the end of the drilling operation, the maximum plastic strain of the model for considering and not considering stress sensitivity was 0.0145 and 0.0138, respectively. Therefore, the established comprehensive model will provide a theoretical support for accurately predicting the engineering geological disasters in hydrate development process. 相似文献
1000.
Applying the statistical damage theory based on the Weibull distribution to describe rock deformation and failure processes is an important development in rock mechanics. The shape parameter of the Weibull distribution, m, determines the basic shape of the distribution curve; additionally, it also represents a physical characteristic which can be applied when constructing rock constitutive models. To study the evolution of m during rock failure when applying the Weibull distribution to rock mechanics, uniaxial cyclic loading tests of shale specimens were conducted and previous rock mechanics experiments under different temperatures and loading rates were reviewed. The results indicate that m varied with the accumulation of damage but was almost constant between the volume expansion point and the peak strength point of each specimen. Combined with previous studies about the accelerated failure behavior of rocks, we conclude that between the volume expansion point and the peak strength point, the mechanical behavior of the rock fracture process did not change significantly. Based on the characteristics of m at different damage stages during the rock failure process, ranges of m values at different damage stages are proposed. The conclusions reached in this study may be used as an important reference for theoretical research on rock mechanics. 相似文献