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41.
42.
A numerical procedure is described for the analysis of the vertical deformation and the stress distribution of the strip footings
on layered soil media. Three layers of soil with different stiffness are considered with the middle soil layer the thinnest
and most stiff layer. The soil media is discretized and using the theory of elasticity, the governing differential equations
are obtained in terms of vertical and horizontal displacements. These equations along with appropriate boundary and continuity
conditions are solved by using the finite difference method. The vertical and horizontal displacements, strains and stresses
are found at various nodes in the soil media. Parametric studies are carried out to study the effect of the placement depth
of the middle soil layer, the relative ratios of the moduli of deformation of the soil layers on the vertical displacement
of the footing and the vertical stress distribution. These studies reveal that the middle thin but very stiff layer acts like
a plate and redistributes the stresses on the lower soft soil layer uniformly. The displacement on the top and bottom of the
middle soil layer is almost the same showing that the compression of the middle layer is negligible as it is very stiff. 相似文献
43.
Study of geothermal water intrusion due to groundwater exploitation in the Puebla Valley aquifer system, Mexico 总被引:1,自引:1,他引:1
E. Leticia Flores-Márquez Gabriel Jiménez-Suárez Raymundo G. Martínez-Serrano René E. Chávez Daniel Silva Pérez 《Hydrogeology Journal》2006,14(7):1216-1230
Significant intrusion of geothermal water into fresh groundwater takes place in the Puebla Valley aquifer system, Mexico. The decline in the potentiometric surface due to the overexploitation of the groundwater induces this intrusion. This hydrological system comprises three aquifers located in Plio-Quaternary volcanic sediments and Mesozoic calcareous rocks. The hydraulic balance of the aquifer shows that the annual output exceeds the natural inputs by 12 million m3. Between 1973 and 2002, a drop in the potentiometric surface, with an 80 m cone of depression, was identified in a 5-km-wide area located southwest of the city of Puebla. Chemical analyses performed on water samples since 1990 have shown an increase in total dissolved solids (TDS) of more than 500 mg/L, coinciding with the region showing a cone of depression in the potentiometric surface. A three-dimensional flow and transport model, based on the hydrogeological and geophysical studies, was computed by using the MODFLOW and MT3D software. This model reproduces the evolution of the aquifer system during the last 30 years and predicts for 2010 an additional drawdown in the potentiometric surface of 15 m, and an increase in the geothermal water intrusion. 相似文献
44.
Substantial damage to water supply systems, including water delivery pipelines, water treatment plants, reservoirs, and water
storage tanks, was reported after the 1999 Chi–Chi Taiwan Earthquake. This paper first summarizes the damage survey and then
presents the results of seismic fragility analysis for underground pipelines. Construction blueprints of the water delivery
pipelines and repair work orders of 11 townships and cities in the disastrous area were digitized into a Geographical Information
System (GIS) for analysis and assessment. With the aid of the GIS system, we found that PVC pipes made up 86% of water delivery
pipelines while steel, cast iron, ductile iron, PE and others took the rest. Therefore, this paper focuses on the fragility
analysis of PVC pipes. Three different methods were applied to derive the fragility relations between the PVC water pipes
having nominal diameters (approximately inner diameters) greater than or equal to 65 mm and earthquake intensity parameters
such as peak ground acceleration and peak ground velocity. The results were then examined with those of other countries. The
discrepancy between our results and the empirical equation used by HAZUS, an earthquake loss estimation software developed
by the Federal Emergency Management Agency was not significant. 相似文献
45.
以中国科学院盐亭紫色土农业生态试验站小流域为例,研究不同土壤侵蚀沉积地段(斜坡和沟谷不同部位)的土壤结构特征,以了解侵蚀沉积对土壤结构的影响。结果表明,在植被覆盖较好的坡体顶部,土壤侵蚀较弱,团聚度达到30.1%,MWD变化为3.4mm,土壤结构良好;沟谷底部由于沉积而有较多细土物质并具有适宜的水分条件,有利于土壤团聚体的形成,结构状况亦较好,团聚度达到50.3%,结构保持率为35.4%;而坡腰侵蚀较严重,团聚度仅为13.6%,结构保持率为14.1%,土壤结构状况较差。 相似文献
46.
IAN YEBOAH 《The Geographical journal》2006,172(1):50-65
This paper is concerned with subaltern actions providing alternatives to development practice. I use Ghana's attempt at urban water privatization to illustrate that Ghana's development practice is characterized by a dependence on foreign sources of capital and expertise that illustrates a psyche and mindset of Eurocentrism associated with the elite and decisionmakers of the country. The rationale for water privatization, the how of privatization, and the anti-development opposition to privatization not only demonstrate this dependency but also the extent to which decisionmakers are willing to sacrifice sovereignty and culturally sensitive ways of doing things, to global capital, in exchange for development funds. In the state's zeal for Western or Occidental development, subalterns in Ghana have devised hybridities that are post-traditional and Oriental in nature to solve their water problems. These development solutions are couched within structures provided to human agency and suggest that development practice should therefore listen to subalterns in terms of how they imagine and solve their problems. The concern with subaltern voices shows the relationship between postcolonial studies and development practice. 相似文献
47.
通过对向斜洼地含水层水文地质特征的勘探及研究,对研究区的水文地质边界条件进行了概化,并用水均衡法估算了地下水资源量,对拟建一级电站引水渠沿线提取地下水进行融冰的可行性进行了研究,并提出了取水方案. 相似文献
48.
49.
淄博市洪山、寨里煤矿区隐伏的奥陶系灰岩裂隙岩溶水污染严重。水质污染突发于矿坑全面闭坑以后,污染范围与矿坑水区一致,地下水污染组份与矿坑水的高含量组份相同。水质恶化主要由矿坑水串层污染所致。在此针对串层污染形成原因及影响因素,提出了防治对策。 相似文献
50.
将广义Kопытов预测模型和乙型水驱曲线方法有机的结合起来,得到了油田开发中后期——递减时期的一种预测水驱开发油田的含水率、产油量、产水量及其相应的累积产量随开发时间变化的方法,此方法克服了在水驱油田预测开发指标中二者所存在的局限性。 相似文献