scholarly journals Distortion of the Estimated Hydraulic Conductivity from a Hydraulic Test in Fractured Rock Due to Excessive Injection or Extraction

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2712
Author(s):  
Sung-Hoon Ji ◽  
Byeong-Hak Park ◽  
Kyung-Woo Park
Keyword(s):  
Hydraulic Conductivity ◽  
Scale Effects ◽  
Fractured Rock ◽  
Reynolds Numbers ◽  
Nonlinear Flow ◽  
Low Permeability ◽  
Forchheimer Equation ◽  
Hydraulic Test ◽  
Different Types ◽  
Constant Head

In this study, we discussed distortion of the estimated hydraulic conductivity from a hydraulic test due to excessive injection or extraction of groundwater by evaluating the influence of nonlinear flow. Pulse, slug, and constant head withdrawal tests with various head displacements were conducted in fractured granite rock, and the changes of representative Reynolds numbers (Re) during the tests were calculated. The Forchheimer equation and cubic law were used to evaluate the influence of nonlinear flow on the hydraulic tests, and thus the possibility of distortion of the estimated hydraulic conductivity. Our results showed that there was little possibility that nonlinear flow occurred during the pulse tests in the test zones. In the slug tests at several test zones, however, the estimated hydraulic conductivities were likely to be distorted due to nonlinear flow. Except for the test zones with low permeability, the scale effects of the estimated hydraulic conductivities from different types of tests were observed. These results indicated that the scale effect and distortion of the hydraulic parameters can be evaluated by conducting various types of hydraulic tests.

Hydraulic Conductivity and Scale Effects Investigation in Basalt in the Dam Area of Xiluodu Hydroelectric Station, Jinshajiang River, China

2013 ◽  
Vol 405-408 ◽  
pp. 2123-2129
Author(s):  
Yuan Yao Li ◽  
Rong Lin Sun ◽  
Ren Quan Chen
Keyword(s):  
Hydraulic Conductivity ◽  
Scale Effects ◽  
Fractured Rock ◽  
Water Pressure ◽  
Hydroelectric Station ◽  
Tracer Test ◽  
Test Results ◽  
Hydraulic Test ◽  
Water Seepage ◽  
Pressure Tests

Hydraulic conductivity (K) and scale effects in basalt in the dam area of Xiluodu hydroelectric station were investigated by three kinds of field hydraulic tests with different test scale, 2608 water pressure tests in single borehole, 54 water seepage tests in adit and groundwater tracer test. Statistical results show the high heterogeneity of fractured rock and K difference between two neighboring test intervals are often more than two orders of magnitude. However, there is a strong decreasing trend of hydraulic conductivity with the increase of vertical depth. Moreover, these three kinds of hydraulic test results demonstrate that hydraulic conductivity increases with the increase of test scale in heterogeneous basalt and the heterogeneous degree of K decreases with the increase of test scale. K from water seepage test in adit, with the test scale of 1-2 m, is dispersed from 0.00024 m/d to 3.46 m/d. K from water pressure test in single borehole, with the test scale of 4-7 m, is 0.0002-1.04 m/d. K from groundwater tracer test, with the test scale of 70-145 m, is concentrated between 0.46 m/d and 2.1 m/d. High heterogeneity of fractured rock and multi-level of fractures are thought as the major reason resulted in scale effects of hydraulic conductivity.

A note on falling-head and rising-tail permeability tests on saturated soils in centrifuge

2020 ◽  
Vol 57 (8) ◽  
pp. 1232-1238
Author(s):  
G.H. Lei ◽  
F.X. Liu ◽  
S.W. Xia
Keyword(s):  
Hydraulic Conductivity ◽  
Generalized Equation ◽  
Saturated Soils ◽  
Low Permeability ◽  
Curve Matching ◽  
Saturated Porous Media ◽  
Soil Specimen ◽  
Practical Application ◽  
Variable Head ◽  
Constant Head

The falling-head and rising-tail method for permeability test allows for both inflow and outflow rates to be conveniently measured. This helps to detect any possible swelling or consolidation of specimen during testing and to identify the continuity of flow of water through the specimen. It has been widely adopted to measure the hydraulic conductivity of saturated porous media of extremely low permeability, such as hydraulic barrier soil materials. Centrifuge permeameter test with this method has recently been devised to accelerate water flow and reduce the time needed for testing. The accompanying equation for calculating hydraulic conductivity is, however, found to be simplified because it was formulated by idealizing such a variable-head test as multiple segmental constant-head tests. In this paper, a new generalized equation is established based strictly on the variable head. Moreover, based on curve matching between the rates of flow into and out of the soil specimen, an approach is also proposed to identify the continuity state of flow. The data relevant to this state are extracted for performing the calculation of hydraulic conductivity. The practical application of the proposed equation and its associated approach is illustrated through a reanalysis of recently published experimental data in the literature.

Using constant head step tests to determine hydraulic apertures in fractured rock

2011 ◽  
Vol 126 (1-2) ◽  
pp. 85-99 ◽  
Author(s):  
Patryk M. Quinn ◽  
Beth L. Parker ◽  
John A. Cherry
Keyword(s):  
Fractured Rock ◽  
Constant Head

Occurrence of Bubbles in a Thin Wire at Low Reynolds Number

1992 ◽  
Vol 114 (2) ◽  
pp. 255-260 ◽  
Author(s):  
K. Sato
Keyword(s):  
Separation Zone ◽  
Reynolds Numbers ◽  
Cavitation Number ◽  
The Other ◽  
Laminar Separation ◽  
Low Reynolds Numbers ◽  
Thin Wires ◽  
Different Types ◽  
Low Reynolds ◽  
Air Diffusion

Thin wires of various diameters from 0.07 to 0.7 mm are examined about appearances and characteristics of bubble occurrence behind them in the range of low Reynolds numbers. The appearance of bubbles is very dependent on diameters of wires. Two different types of bubbles can be observed in the present experiment. One is a streamer-type bubble for smaller wires and the other is a small unspherical bubble for larger wires. The incipient and the desinent values of cavitation number also change greatly with the bubble types. The streamer-type bubble is related to the presence of laminar separation zone and the growth due to air diffusion. The small unspherical bubble can be mainly attributed to the motion of rolled-up vortices and the growth due to vaporization.

scholarly journals Effect of Ammonium on the Hydraulic Conductivity of Kaolin and Bentonite as Clay Liners

2020 ◽  
Vol 4 (2) ◽  
pp. 100-111
Author(s):  
Adebola Adebayo Adekunle ◽  
Igba Uvieoghene Tobit ◽  
Ogunrinola Oluwaseyi Gbemiga
Keyword(s):  
Hydraulic Conductivity ◽  
Ground Water ◽  
Tap Water ◽  
Bentonite Clay ◽  
Research Paper ◽  
Low Permeability ◽  
Main Function ◽  
Clay Liners ◽  
Landfill Liners ◽  
Different Sources

: Landfill liners are underlying materials with low permeability whose main function is to mitigate the infiltration of toxic contents into ground water lying beneath. Landfill liners are primarily made of bentonite clay. Bentonite has a very low hydraulic conductivity, that might not be readily accessible, unlike kaolin which is found to have a lower hydraulic conductivity compared to that of bentonite and can be extensively obtained from numerous different sources. Explored, for the purposes of the present research paper, were various ratios of bentonite and kaolin and their hydraulic conductivity, in particular ratios of 90:10 kaolin to bentonite, 80:20 kaolin to bentonite, 70:30 kaolin to bentonite, 60:40 kaolin to bentonite and 50:50 kaolin to bentonite in an effort to achieve an acceptable barrier suitable as a liner / where tap water and ammonium solution were used as permeants. It was concluded that the ratios not lower than 20% bentonite (80:20, 70:30, 60:40 and 50:50) all had their hydraulic conductivity value reduced compared to the 100% kaolin.

scholarly journals Comparison of three measurement methods of saturated hydraulic condutivity

2006 ◽  
Vol 3 (3) ◽  
pp. 987-1019 ◽  
Author(s):  
C. Fallico ◽  
E. Migliari ◽  
S. Troisi
Keyword(s):  
Hydraulic Conductivity ◽  
Measurement Method ◽  
Sandy Loam ◽  
Measurement Methods ◽  
Soil Core ◽  
Statistical Parameters ◽  
Factors Affecting ◽  
Average Value ◽  
Constant Head ◽  
Log Normal

Abstract. After pointing out the importance of the saturated hydraulic conductivity (ks) measurements and the difficulties and uncertainties that are present, and after recalling salient aspects of three well-known measurement methods of this parameter (i.e. constant-head tension infiltrometer (TI) method, constant-head pressure infiltrometer (PI) method and soil core (SC) estimates method), the results of an investigation on data which were obtained during a measurement campaign on an area of 800 m2, on a sandy loam hillslope, located in Southern Italy, were carried out again here. Three sets of values of ks, obtained with these measurement methods, were analyzed statistically, verifying that the log-normal distribution describes these better than the normal one; moreover, the more significant statistical parameters of each set were compared (average value , amplitude A, coefficient of variation CV and standard deviation SD), individualizing the more significant differences. The greatest value of hydraulic conductivity was found with method (PI), while the smallest with (SC) and the intermediate with (TI); these differences were translated into macroporosity and into the influence of the single measurement method. Moreover, referring to the possible factors affecting the results, the importance can be noted of the structure, the texture and the soil events, in terms of utilization, which can affect the measure of ks leading often to very different values even for similar soils, but with a different history, independently of the coincidence of the measurement points and they can be determining to explain the differences affecting the results obtained in analogous investigations by other researchers. Having confirmed that generalization is not possible, the need was emphasized to adopt the necessary devices relating to the specific measurement method, case by case, and to carefully explain the obtained results, in the light of the peculiarities and the limits of each situation. Finally, the results of similar statistical analysis carried out on a greater number of ks values, measured through the (TI) and (PI) methods are shown in this paper, with some statistical considerations on the increasing of the measurements number.

scholarly journals An Estimation Model for Hydraulic Conductivity of Low-Permeability and Unfilled Fractured Granite in Underground Water-Sealed Storage Caverns

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Yangbing Cao ◽  
Weiguo Gong ◽  
Xiangxiang Zhang ◽  
Junxi Chen ◽  
Zhenping Huang
Keyword(s):  
Hydraulic Conductivity ◽  
Water Pressure ◽  
Underground Structure ◽  
Underground Water ◽  
Stress Index ◽  
Low Permeability ◽  
Proposed Model ◽  
Imaging Results ◽  
Water Conduction ◽  
Fractured Granite

The permeability of rock mass is closely related to the stability and safety of underground structure, especially in underground water-sealed storage caverns. With regard to the estimation approaches in predicting the hydraulic conductivity of fractured granite in water-sealed storage caverns, there are some limitations of parameter selection leading to poor applicability. Focusing on the contribution of the water conduction fractures (WCF) to the hydraulic conductivity, we attempted to propose a novel model, the CA model, for estimating its hydraulic conductivity based on the fracture orientation index and the normal stress index by analyzing the borehole wall imaging results and borehole water-pressure test results in the site of underground water-sealed storage caverns. The results indicated that the proposed model is suitable for low-permeability and unfilled fractured granite, exhibiting good effectiveness by clarifying the relation between geomechanical parameters and hydraulic behavior. Further, the parameters upon which the proposed model is based are representative and easy to obtain, which has certain guiding significance and reference value for analyzing the permeability characteristics of similar rock masses.

scholarly journals CONTROLE ESTATÍSTICO DE QUALIDADE DA CONDUTIVIDADE HIDRÁULICA EM LUVISSOLO E NEOSSOLO COM VARIAÇÃO DA DENSIDADE DO SOLO

Irriga ◽  
2019 ◽  
Vol 24 (1) ◽  
pp. 16-24
Author(s):  
Floriano Luiz Suszek ◽  
Silvio Cesar Sampaio ◽  
Vera Lucia Antunes De Lima
Keyword(s):  
Hydraulic Conductivity ◽  
Control Charts ◽  
Density Variation ◽  
Statistical Quality Control ◽  
Agricultural Drainage ◽  
Sensitivity Index ◽  
Statistical Control ◽  
Soil Physics ◽  
Constant Head ◽  
Improving Accuracy

CONTROLE ESTATÍSTICO DE QUALIDADE DA CONDUTIVIDADE HIDRÁULICA EM LUVISSOLO E NEOSSOLO COM VARIAÇÃO DA DENSIDADE DO SOLO     FLORIANO LUIZ SUSZEK1; SILVIO CÉSAR SAMPAIO2 E VERA LÚCIA ANTUNES DE LIMA3   1Doutor em Engenharia Agrícola, Programa de Pós-Graduação em Engenharia Agrícola (PGEAGRI), Universidade Estadual do Oeste do Paraná (UNIOESTE), Rua Universitária, nº 1619 – Jd. Universitário, CEP: 85809-110, Cascavel, Paraná, Brasil, [email protected]. 2Universidade Estadual do Oeste do Paraná, Departamento de Recursos Hídricos e Saneamento Ambiental, Rua Universitária, nº 1619 – Jd. Universitário, CEP: 85809-110, Cascavel, Paraná, Brasil, [email protected]. 3Universidade Federal de Campina Grande (UFCG), Centro de Tecnologia e Recursos Naturais, Rua Aprígio Veloso, nº 882, Universitário, CEP: 58429-900, Campina Grande, Paraíba, Brasil, [email protected].     1 RESUMO   A condutividade hidráulica é um dos principais fatores para dimensionamento de sistemas de drenagem agrícola. Uma das metodologias utilizadas para a obtenção da condutividade hidráulica é o permeâmetro de carga constante. Porém a grande variação dos resultados gera necessidade de análises para melhorar a precisão destes, como o uso de gráficos de controle estatístico de qualidade. Este trabalho analisou por meio de gráficos de controle, a metodologia do permeâmetro de carga constante para dois solos diferentes na obtenção da condutividade hidráulica, variando a densidade dos solos e analisando seu índice de sensibilidade. O LUVISSOLO CRÔMICO é mais sensível à variação de densidade do solo, para a condutividade hidráulica, do que o NEOSSOLO REGOLÍTICO. Os gráficos de controle foram úteis na melhoria da precisão dos valores analisados, mostrando a variação da condutividade hidráulica e quais foram os pontos fora dos limites desejáveis.   Palavras-chave: Drenagem agrícola, propriedades físicas do solo, permeâmetro de carga constante.     SUSZEK, F. L.; SAMPAIO, S. C.; LIMA, V. L. A. de STATISTICAL QUALITY CONTROL IN HYDRAULIC CONDUCTIVITY FOR LUVISOL AND ENTISOL WITH DENSITY VARIATION     2 ABSTRACT   Hydraulic conductivity is one of the main factors for the design of agricultural drainage systems. One of the methodologies used to obtain the hydraulic conductivity is the constant head permeameter. However, the large variation of results generates the need for analyzes to improve their accuracy, such as the use of quality statistical control graphs. This work analyzed, by means of control charts, the methodology of constant head permeameter for two different soils in obtaining hydraulic conductivity, varying the density of soils and analyzing their sensitivity index. Luvisol is more sensitive to density variation, for hydraulic conductivity, than  entisol. Control graphs were useful in improving  accuracy of the analyzed values, showing the variation of hydraulic conductivity and what were the points outside the desirable limits.   Keywords: Agricultural drainage, soil physics properties, constant head permeameter.

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