共查询到19条相似文献,搜索用时 140 毫秒
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作为反滤材料的土工织物尽管在岩土工程中使用越来越广泛,但决定其应用效果的渗透性能却在试验中往往不易准确测得。除了试验中的多种影响因素外,就常规渗透仪而论,漏水问题常常较难解决。本文使用改进的渗透仪对多种土工织物加荷条件下行政区域渗秀性能进行了试验研究,为三峡工程某排水管道中拟采用的土工织物反滤材料的设计提供了可行性对比和分析。 相似文献
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针对乳胶膜式压密注浆土钉的潜在缺陷,提出了采用土工织物替代乳胶膜改进该土钉的新思路。首先,基于自研的土工织物反滤性能测定装置,开展了一系列水泥浆液反滤试验,研究了水灰比、浆液体积和注浆压力对土工织物反滤性能的影响,得到了注浆过程中上述影响因素影响下反滤时间和水灰比的变化规律。其次,对反滤前/后的砂土进行了贯入试验,评估了由于浆液中黏性物质入渗引起的周围土体强度提高。再次,对反滤前/后的水泥试块进行了单轴压缩试验,探明了节泡(水泥试块)强度显著提高的原因是土工织物反滤过程中节泡内水灰比的降低。最后,开展了土工织物和乳胶膜式压密注浆土钉的两组对比拉拔试验,验证了土工织物改进压密注浆土钉的优越性。研究成果能为压密注浆土钉的优化和应用奠定基础。 相似文献
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土工织物已广泛用于公路、铁路及坝体的隔离、反滤和加固等。但用于建筑物地基处理尚属罕见。本文列举了土工织物在工业建筑地基上应用实例,介绍了土工织物的材料性能、结构构造及其工程设计、施工要点。 相似文献
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本文中通过进行循环往复水流条件下的梯度比试验,研究了三种不同开孔孔径的无纺土工织物分别作为反滤层时,其各自的反滤性能。通过分析被保护土体各部分渗透系数的变化来研究土工织物的反滤淤堵机理,探究了经典反滤理论在循环往复水流条件下的正确性、适用性和局限性。 相似文献
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分别配制不同孔隙比的粉砂、标准砂和黏土试样,采用自主研制的一套多功能渗透试验装置,开展了一系列纯土和有纺土工织物覆土条件下的渗透试验,对比分析了这两种条件下渗透系数的差异,并探讨了有纺土工织物与土共同作用下的渗透机理。结果表明,有纺土工织物对于土体渗流略有一定的抑制作用,表现为覆土条件下的渗透系数略小于纯土的渗透系数,但是对于粉砂,当其孔隙比比较大、细砂颗粒的含量相对较多时,细砂颗粒则有可能在渗流作用下通过有纺土工织物孔隙而产生流失,使得覆粉砂条件下的渗透系数略大于纯粉砂的渗透系数。 相似文献
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The measurement of permeability forms the basis for many engineering and geological engineering investigations. Most of these investigations require that a large number of determinations be made rapidly and accurately. The permeameter discussed here is a modification of the one designed by Ohle (1951). The permeameter allows for rapid sample change and is capable of measuring the permeability of a core sample using any fluid. The permeameter has been used successfully to test permeabilities as low as 10?5 millidarcies to permeabilities as high as 10 millidarcies at fluid pressures up to 10 MPa. The reproducibility of the tests was found to be in the order of 90%. 相似文献
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利用非饱和三轴渗气仪研究了压实高庙子膨润土的渗气特性。发现当渗气系数小于10~(-14) m~2时,压实膨润土中的Klinkenberg效应较为显著,渗气系数会随气压力的增大而降低;气体滑脱因子随Klinkenberg渗气系数与体积含气率之比的变化满足幂函数关系,试验得到的二者之间关系与干密度、含水率无关,并与Klinkenberg理论模型相近;Klinkenberg渗气系数与体积含气率在双对数坐标中呈线性关系,其斜率与含水率基本无关。基于试验规律,建立了考虑Klinkenberg效应的高庙子膨润土非饱和渗气系数的数学模型。 相似文献
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《Geotextiles and Geomembranes》2022,50(6):1172-1187
This study develops a coupled model of chemical clogging and permeability coefficient of geotextile envelope. Based on the distribution characteristics of crystal precipitates on geotextile envelope and their influence on the permeability coefficient, a permeability coefficient model of an actual geotextile envelope that considers the overlapping effect is developed. Then, the densification effects of geosynthetic fiber hypothesis and the filter cake effect hypothesis are proposed to simulate the processes of increasing fiber diameter after crystal precipitation and the accumulation of crystal precipitates on the surface of geotextile envelope. The crystal precipitation module and permeability coefficient module are coupled, and their experimental values are used to confirm the availability of the model. Results indicate the satisfactory performance of the model. In addition, the parameter sensitivity analysis and trend prediction show that the saturation index SI and solution flow rate V are the main factors that affect the chemical clogging and permeability of geotextile envelope. When the solution conditions are not considered, the sensitivity of geotextile envelope parameter df increased with the amount of precipitation in crystal precipitation. When the pores of the geotextile envelope are completely clogged, the permeability coefficient of the geotextile envelope will drop sharply, then decline slowly. 相似文献
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膨胀条件下混合型缓冲回填材料的渗透特性 总被引:2,自引:0,他引:2
选取内蒙古高庙子膨润土(GMZ001膨润土),分别向其中添加0%,10%,20%,30%,40%,50%的石英砂,采用电子压力试验机在20 MPa荷载下静力压实制样,利用柔性壁渗透仪实测300 kPa围压条件下膨润土–石英砂混合物的渗透系数和体积膨胀变化。研究表明,在0%~50%掺砂率范围内,GMZ001膨润土–石英砂混合物的渗透性随掺砂率增大没有明显的变化,能够满足高放废物处置缓冲回填材料低渗透性的要求。引入有效黏土密度的概念,分析掺砂率和干密度对渗透系数的共同影响可知,膨润土–石英砂混合物渗透系数的对数值与有效黏土密度存在良好的线性衰减关系。结合压实试验结果发现,GMZ001膨润土–石英砂混合物的渗透系数为掺砂率的单值函数,据此提出不同压实条件下GMZ001膨润土–石英砂混合物渗透系数的预测关系式,期望为混合型缓冲回填材料的配比优化提供理论依据。 相似文献
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Chuang Yu Yu Yang Ze-xiang Wu Ji-fang Jiang Rao-ping Liao Yong-feng Deng 《Geotextiles and Geomembranes》2021,49(2):413-419
Geosynthetic clay liners (GCLs), which have a very low permeability to water and a considerably high self-healing capacity, are widely used in liner systems of landfills. In this study, a series of experimental tests were carried out under complex conditions on typical commercial GCLs from China. In particular, the effects of pH values and lead ions (Pb2+) were tested in addition to other factors. The swelling properties of natural bentonite encapsulated between geotextile components in the GCLs were tested first. The swelling capacity was reduced rapidly at pH values < 3 and concentrations of Pb2+ >40 mM. Permeability tests on GCLs with different concentrations of lead ions were then performed by using the self-developed multi-link flexible wall permeameter, and data showed that increases in lead ion concentrations greatly improved the permeability. Finally, self-healing capacity tests were conducted on needle-punched GCLs under different levels of damage. Results showed that the GCLs have a good self-healing capacity with small diameter damage holes (2 mm, close to three times the original aperture), but with a damage aperture larger than 15% of the sample area, the self-healing capacity could not prevent leakage; hence, in certain situations it will be necessary to repair the damage to meet the anti-seepage requirement. 相似文献
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土石混合体作为土和石块的介质耦合体,具有非均质性、非连续性及试样的难以采集性等内在的独特的性质,从而给研究带来极大的困难。土石混合体属于典型的多孔介质,其渗透特性与颗粒的大小、孔隙比及颗粒形状关系密切。本文采用室内正交实验,利用自制的常水头渗透仪,研究了砾石含量、孔隙比和颗粒形状3个因素在不同水平下对土石混合体渗透系数的影响。通过正交试验确定了3种因素对土石混合体渗透系数的影响顺序及各因素的显著性水平。提出了土石混合体渗透系数计算公式,并通过试验结果验证了计算公式的正确性,为土石混合体渗透系数的理论计算提供了一个简明有用的计算工具。 相似文献
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对深圳河治理工程边坡防护反滤运行期的土工布进行了综合试验研究 ,分析了土工布长期运行过程中的渗透性、保土性和淤堵性能 ,从强度损失角度分析了土工布长期运行的强度衰减情况 ,并对土工布的耐久性进行了试验分析。由试验知 ,土工布渗透系数降低约 10 0倍左右 ,而土工布强度降低了 5 0 %左右 ,强度衰减速率小于 0 .2 6% /月。试验表明 ,土工布已进入稳定渗透期和强度的稳定衰减期 ,土工布满足防护反滤的要求 相似文献
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《Geotextiles and Geomembranes》2020,48(5):735-746
This study investigates the influence of clogging substances on pore characteristics and permeability of geotextile envelopes that were used for 3, 7 and 15 years in irrigated farmlands in Xinjiang region, which is arid and suffers from the soil salinity problem. Results show that the macropores (above 125 μm) of envelopes are evidently clogged, whereas the smaller pores less than 100 μm are still unblocked after operation. The permeability coefficients of geotextile envelopes after serving for 3 and 15 years are smaller than the minimum required permeability coefficients after clogging. The main chemical components of clogging substances in the geotextile envelope are silicon dioxide and calcium carbonate. Calcium carbonate content of the geotextile envelope is consistent with calcium carbonate content of soil. Chemical clogging susceptibility increases with the operation time of the subsurface drainage pipes. The ratio of O90 size of envelope material over d90 of soils (O90/d90) and saturation index (SI) can be used to assess the susceptibility of physical and chemical clogging respectively. This study provides a preliminary reference for estimating the clogging susceptibility of geotextile envelopes in arid areas. 相似文献
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Chenyao Guo Haoyu Yang Zhongbing Lin Jingwei Wu Hang Li Zhe Wu Wei Mao 《Geotextiles and Geomembranes》2021,49(4):941-951
This paper focuses on the effects of chemical precipitation on the permeability of geotextile envelopes for a subsurface drainage system in arid areas by conducting precipitation experiments of the geotextile in static or flowing solution. The results show that the precipitation process is not significantly promoted or inhibited by the network structure of geotextile. The precipitates in the form of rhombus wrap around the fiber surface. The number of geotextile pores with the smaller diameters decreases significantly after precipitation experiments. As the increase of the area density of precipitates (ΔR), the variation of the pore area (ΔS) and the variation of permeability coefficient (ΔK) of the geotextile decrease rapidly at first and then slowly. The ΔK and ΔS VS ΔR data were best fitted with logarithmic trend line. This study provides a preliminary reference for quantifying the chemical clogging process of geotextile envelopes in arid areas. 相似文献