Using High Hydraulic Conductivity Nodes to Simulate Seepage Lakes

This paper presents a case history of the leakage behavior during dewatering tests in the gravel strata of an excavation pit of a metro station in Hangzhou, China. The groundwater system at the test site is composed of a phreatic aquifer underlain by an aquitard and a confined aquifer with coarse sand and gravel. The sandy gravel stratum has very high hydraulic conductivity. The maximum depth of the excavation is 24 m below the ground surface, which reaches the middle of the aquitard strata, where the thickness of the clayey soil is insufficient to maintain the safety of the base of the excavation. To understand the hydrological characteristics of gravel strata, single- and double-well pumping tests were conducted, where a cut-off wall was installed 43 m deep with its base penetrating 2 to 3 m into the aquifer. Test results show that this partial cut-off of the aquifer cannot effectively protect the base of the excavation from the upward seepage force of the groundwater during excavation. Therefore, a new cut-off wall (second phase) was constructed to a depth of 54 m to cut off the confined aquifer. A second pumping test was conducted after the construction of the second phase cut-off wall, and test results show that this full cut-off combined with dewatering can control groundwater effectively during excavation. This finding indicates that when a deep excavation is conducted in a confined aquifer with high hydraulic conductivity, determination of the depth of the retaining wall should be based on three factors: the stability of the base, the upward seepage stability, and settlement control.

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Resistance of ascending vasa recta to transport of water

AJP Renal Physiology ◽

10.1152/ajprenal.1991.260.3.f303 ◽

1991 ◽

Vol 260 (3) ◽

pp. F303-F310 ◽

Cited By ~ 7

Author(s):

T. L. Pallone

Keyword(s):

Hydraulic Conductivity ◽

Capillary Pressure ◽

Single Injection ◽

Fluorescein Isothiocyanate ◽

Free Flow ◽

Volume Flux ◽

Group I ◽

Vasa Recta ◽

Group Ii ◽

High Hydraulic Conductivity

A study was undertaken to determine the effect of increasing capillary pressure on volume flux in ascending vasa recta (AVR). In one experiment (group I), AVR were blocked by a single injection of paraffin wax and subjected to free-flow microperfusion at 10 nl/min. Collected fluid was obtained from the perfused vessels by micropuncture. In a second experiment (group II), AVR segments were isolated between two paraffin blocks and perfused at 10 nl/min. In group II, the collection pipette was pressurized to 0, 10, or 20 mmHg. Transmembrane volume flux was determined by measuring the change in concentration of fluorescein isothiocyanate-labeled dextran (2 x 10(6) mol wt) from perfusate to collected fluid. In group I, measurements revealed a capillary pressure of 10.3 +/- 0.5 (SE) mmHg and volume flux of 4.3 +/- 1.0 nl.mm-1.min-1. In group II, volume flux was 1.8 +/- 1.3, 5.9 +/- 1.0, and 11.2 +/- 1.1 nl.mm-1.min-1 at collection pressures of 0, 10, or 20 mmHg, respectively. Based on these data and an AVR diameter of 20 microns, AVR hydraulic conductivity is between 12.5 x 10(-6) and 18.7 x 10(-6) cm.s-1.mmHg-1. The papillary AVR have a high hydraulic conductivity. This is consistent with their role as the sole conduit for removal of water from the papillary interstitium.

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Minimum Safe Burial Depth of Submarine Pipelines in Well Graded and High Hydraulic Conductivity Sand

The International Journal of Ocean and Climate Systems ◽

10.1260/1759-3131.2.3.225 ◽

2011 ◽

Vol 2 (3) ◽

pp. 225-247

Author(s):

S. Neelamani ◽

K. Al-Banaa

Keyword(s):

Hydraulic Conductivity ◽

Burial Depth ◽

High Hydraulic Conductivity

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ANALISIS PENGARUH NILAI KONDUKTIVITAS HIDRAULIK DAN DISPERSIVITAS DINAMIK TERHADAP REMEDIASI AIR TANAH MENGGUNAKAN SIMULASI NUMERIK

Jurnal Teknik Hidraulik ◽

10.32679/jth.v12i2.658 ◽

2021 ◽

Vol 12 (2) ◽

pp. 107-118

Author(s):

Agus Mochamad Ramdhan ◽

Arifin Arifin ◽

Erik Hermawan ◽

Lambok M. Hutasoit

Keyword(s):

Numerical Simulation ◽

Sensitivity Analysis ◽

Hydraulic Conductivity ◽

Groundwater Remediation ◽

Flow Simulation ◽

Pumping Wells ◽

Time Required ◽

Close Distance ◽

High Hydraulic Conductivity

Groundwater remediation is one of the solutions to restore the contaminated groundwater. This study was conducted to determine the effect of hydraulic conductivity and dynamic dispersivity on the groundwater remediation effectiveness. As a case study, in 2020, in an area located in Balikpapan, groundwater remediation will be carried out by injecting water containing NaOH through five wells and pumping it back through five wells to form a cycle. The method used is a numerical simulation consisting of groundwater flow simulation, mass transport, and sensitivity analysis. The results show that it takes 124 to 300 days for the injected NaOH to arrive at the pumping wells. The sensitivity analysis results show that when the hydraulic conductivity value is ten times greater, the time required is reduced to 84 to 172 days. Meanwhile, when the dynamic dispersivity is twice larger, the time required is reduced to 75 to 189 days. These results indicate that the groundwater remediation method will be effective for aquifers with high hydraulic conductivity and dynamic dispersivity values. For the study area, the groundwater remediation is suggested to be carried out by increasing the number of injection and pumping wells with a relatively close distance, i.e., around 10 meters, so that NaOH arrives at the pumping wells more quickly.Keywords: groundwater, remediation, hydraulic conductivity, dynamic dispersivity, numerical simulation

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Infiltration from semi-circular furrows in the field

Soil Research ◽

10.1071/sr9690277 ◽

1969 ◽

Vol 7 (3) ◽

pp. 277 ◽

Cited By ~ 2

Author(s):

T Talsma

Keyword(s):

Hydraulic Conductivity ◽

Spatial Variability ◽

Soil Properties ◽

Qualitative Agreement ◽

One Dimensional ◽

Infiltration Rates ◽

Cumulative Infiltration ◽

Field Soils ◽

Gravity Effects ◽

High Hydraulic Conductivity

Experiments on a number of field soils have provided data to check the applicability of recently proposed theory on infiltration from semi-circular furrows. Although spatial variability of soil properties was rather high, the theoretical solutions adequately described cumulative infiltration. The effect of gravity on flow, which is dependent on furrow radius and the ratio of hydraulic conductivity to sorptivity, is not necessarily greatest in soils of high hydraulic conductivity. In most soils gravity effects were pronounced. Qualitative agreement was found between the observed advance of wet fronts and those the theory predicts. Steeper moisture gradients exist near the furrow than would occur near the surface during one-dimensional flow in the same soil. Some factors of relevance to furrow irrigation, and estimation of final infiltration rates from 'short furrow' tests, are discussed.

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