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1.
Geotextile filters are rapidly replacing graded granular filters as the standard of practice in geotechnical design. The objective of the present study is to predict the behavior of the geotextile filter for the locally (Roorkee—India) available soils using three different geotextiles (two nonwoven and one woven). Nonwoven geotextiles are commonly used in filtration applications. This paper evaluates the long-term performance of two needle-punched nonwoven geotextiles and one woven geotextile. Filtration tests on soil–geotextile filter systems were conducted in the laboratory in order to evaluate the filtration and clogging behavior. Laboratory test program, include evaluation of performance of two different nonwoven and one woven geotextile filters in combination with locally available Solani River Sand and Clayey Soil. The paper describes the concept and details of the Fine Fraction Filtration (F3) test and presents data on three different geotextiles, which were evaluated using three different soil types. It is deduced that in all filtration applications, the non-woven geotextile would perform better than the woven geotextile.  相似文献   
2.
以宁波瑞福特气体储运有限公司20,000m3低温乙烯终端和配套公用工程项目的设计为例,介绍了PDSOFT三维配管软件在石油化工储运中的应用。通过项目对该软件的使用过程进行较深入的描述分析、同时对该软件在石油化工储运设计中应用前景和应注意的问题进行了说明。  相似文献   
3.
唐益群  林志  叶为民  黄雨 《工程地质学报》2002,10(S1):186-189,206
首先针对渗流破坏的机理进行研究,区别在堤防工程中常用的流土和管涌的概念,从现有的大量土的渗流破坏的实验资料,结合理论分析,从微观的角度去阐述渗流破坏的形成机理,提出了在级配连续性土和级配不连续性土中进行管涌型土和流土型土判别的标准.然后从定量的角度去推导出各种渗流破坏类型的判别公式以及临界抗渗坡降计算公式.  相似文献   
4.
Electrical resistivity survey and the geotechnical SPT blow counts (N value) method were simultaneously analyzed to investigate the stability of a center-core type earth-fill dam against the seepage phenomenon. The coupling of these heterogeneous field methods provided a chance to understand the status of underground material by comparing the geophysical and geotechnical view. The analysis shows that the zones with low resistivity value generally have low N value, which means low stiffness. However, some zones with a high resistivity pattern are not accompanied by an increase of its N value, and are even showing a lower N value. These results imply that one should be careful to directly correlate resistivity value with the real status of the core material of a fill dam. And a highly resistive zone may be in poor status due to the effect of increase of resistivity value as a result of the piping condition. Additional laboratory tests show that there is a deficiency of fine soil particles believed as the clay at the troubled region, which means an increase in resistivity value. Therefore, multiple explorations should be planned to reduce the uncertainty in application of geophysical methods to dam safety evaluation in order to compensate the resistivity information of core material.  相似文献   
5.
Part of the mountainous semi-arid areas of Iran is geologically and topographically susceptible to landslides. A study was conducted at the Merek catchment, Iran which is geologically characterized by limestone, sandstone, shale and marls so as to determine the factors responsible for the occurrence of landslides. In this study, geomorphological units within the catchment were mapped by overlapping geological, topographical, land use and erosion data, using satellite image and GIS. Rocks and soils were sampled within each unit to determine their physico-chemical and mineralogical properties. It was found that landslides have affected about 15% of the Merek catchment and that their occurrence were promoted by unstable soils, being eroded at the rate of 18.57 t ha−1 yr−1. These landslides were initiated by crack formation in areas having smectite, a mineral which can swell and contract, depending on the availability of water. Smectite is the dominant mineral in about 80% of the area affected by landslides. Low aggregate stability in the topsoil further promotes the occurrence of landslides. Field verification showed that landslides occur mainly in the forest where the canopy cover is less than 15% with slope of 10-40%. Deforestation, overgrazing and improper tillage practices were found to accelerate landslides in this catchment.  相似文献   
6.
Ground cracks in Ethiopian Rift Valley: facts and uncertainties   总被引:2,自引:0,他引:2  
No accurate relationship has been obtained in this study between ground cracks in Ethiopian Rift Valley and the most common causes of earth fissures such as aquifer-system compaction and increased horizontal seepage stresses. This is due to the fact that the level of groundwater withdrawal responsible for these processes is still negligible in Ethiopia. If aquifer-system compaction and increased horizontal seepage stresses have a certain role, then it should be through the long-term effect of groundwater flow from basins to neighboring lakes. The ground cracks appeared also not to have a direct link with active faulting or distant earthquakes. Structurally, the Ethiopian Rift Valley is dominated by NE–SW-trending tensional faults, but no evidence is obtained in this study to associate the process of surface cracking with major tectonics. However, an aseismic elastic strain, which originates at depth and propagates upward through sediments without the formation of bedrock faults, could result in conditions conducive to the development of cracks. Then, fissures might ultimately be created after heavy rainfalls by near-surface processes such as piping and hydrocompaction along water-line sources.  相似文献   
7.
 Sinkhole development along the western shore of the Dead Sea became a major concern in 1990 with the appearance of a series of holes 2–15 m diameter and up to 7 m deep in the Newe Zohar area. One of these sinkholes, below the asphalt surface of the main road along the western shore of the Dead Sea, was opened by a passing bus. Repeated infilling and collapse of these holes indicated the extent of this ongoing process and the significance of this developing hazard. Since then sinkholes have developed in other areas including Qalia, Ein Samar, Ein Gedi and Mineral Beach. Three main types of sinkholes have been recognized. Gravel holes occurring in alluvial fans, mud holes occurring in the intervening bays of clay deposits between fans and a combination of both types at the front of young alluvial fans where they overlap mud flats. Fossil, relict sinkholes have been observed in the channels of some old alluvial fans. Sinkhole development is directly related to the regression of the Dead Sea and the corresponding lowering of the regional water table. Continuation of this process widens the neritic zone enveloping the sea and increases the sinkhole hazard of the region. Received: 4 February 1999 · Accepted: 8 April 1999  相似文献   
8.
A numerical approach for simulating piping erosion is proposed based on an auto-adaptive moving mesh. This approach adapts a flownet mesh (FM) to discretize the domain. It reduces the simulation of two-dimensional transport of moving particles to one-dimensional problem by taking advantages of flow tube concept. Furthermore, it employs a stepwise procedure to decouple the solid-liquid interaction equations for modeling piping erosion. Specifically, the FM is updated and evolved automatically in accordance to simulated erosion since the flownet is refined in high-velocity regions, where the piping erosion progresses. Therefore, the FM is auto-adaptive to the piping erosion paths.  相似文献   
9.
高压摆喷注浆在长沙市堤防建设中的应用   总被引:1,自引:0,他引:1  
蒋友清  熊伟光 《湖南地质》2001,20(2):126-130
为防止长沙市21.8km重点堤防的管涌、涌漏等隐患,提高堤防的抗洪能力,采用高压摆喷浆施工对其进行了整修、加固。较详细地介绍了设备的选择、孔间距及工艺参数的调整、工序安排和工程质量及检测方法。堤防中摆喷连结心墙的围井检测表明,高喷注浆是处理长沙市防洪堤防第四系松散地基的一项设备简便、噪音小、施工快、成本低、防渗效果好的工艺。  相似文献   
10.
细粒含量判别法是无黏性粗粒土渗透变形类型主要判别方法,但细粒含量Pc35%渗透变形类型为管涌的碎砾石,其渗透变形类型不符合细粒含量判别准则。通过对46个工程310个试样(其中细粒含量Pc35%试样35个)的渗透变形试验结果统计分析,结果表明,其颗粒级配曲线具有独特特征,即级配曲线两端段斜率较陡,中间段斜率较缓,有高达87.5%试样颗粒级配为不良级配。进一步分析发现其D15/d85均大于5,即其渗透变形试验结果与反滤设计准则是一致的。进而提出用反滤设计准则D15/d855作为判别该类土的方法,以此作为细粒含量判别法的有益补充。  相似文献   
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