A Study on the Impermeability of Composite Clay of Sanitary Landfill in Loess Area

2013 ◽  
Vol 281 ◽  
pp. 607-614 ◽  
Author(s):  
Jian Feng Gou ◽  
Zheng Zhong Zeng ◽  
Hao Lei Guo ◽  
Hao Wang ◽  
Xiao Li Wang ◽  
...  
Keyword(s):  
Pollution Control ◽  
Permeability Coefficient ◽  
Soil Layer ◽  
Clay Content ◽  
Red Soil ◽  
National Standards ◽  
Sanitary Landfill ◽  
Loess Area ◽  
Permeability Coefficients ◽  
Compacted Loess

Through the compaction and permeability tests on loess, either natural or compacted loess can meet the requirement of the Landfill Pollution Control Standards about impermeable clay. While the compaction weathered red soil layer of the tertiary, widely distributing under the loess, whose permeability coefficient is less than 1×10-7cm/s. In this study we mixed loess with weathered red soil to obtain a new kind of composite soil, and drew a conclusion that the composite soil can meet the requirements of Chinese national standards. When the clay content of composite soil reached 21%, the permeability coefficients are generally able to meet the requirement.

scholarly journals The Influence of Bedding Planes and Permeability Coefficient on Fracture Propagation of Horizontal Wells in Stratification Shale Reservoirs

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Yuepeng Wang ◽  
Xiangjun Liu ◽  
Lixi Liang ◽  
Jian Xiong
Keyword(s):  
Permeability Coefficient ◽  
In Situ Stress ◽  
Stress Difference ◽  
Strength Parameters ◽  
Breakdown Pressure ◽  
Permeability Coefficients ◽  
Bedding Planes ◽  
Initiation Pressure ◽  
Shale Reservoirs

The complexity of hydraulic fractures (HF) significantly affects the success of reservoir reconstruction. The existence of a bedding plane (BP) in shale impacts the extension of a fracture. For shale reservoirs, in order to investigate the interaction mechanisms of HF and BPs under the action of coupled stress-flow, we simulate the processes of hydraulic fracturing under different conditions, such as the stress difference, permeability coefficients, BP angles, BP spacing, and BP mechanical properties using the rock failure process analysis code (RFPA2D-Flow). Simulation results showed that HF spread outward around the borehole, while the permeability coefficient is uniformly distributed at the model without a BP or stress difference. The HF of the formation without a BP presented a pinnate distribution pattern, and the main direction of the extension is affected by both the ground stress and the permeability coefficient. When there is no stress difference in the model, the fracture extends along the direction of the larger permeability coefficient. In this study, the in situ stress has a greater influence on the extension direction of the main fracture when using the model with stress differences of 6 MPa. As the BP angle increases, the propagation of fractures gradually deviates from the BP direction. The initiation pressure and total breakdown pressure of the models at low permeability coefficients are higher than those under high permeability coefficients. In addition, the initiation pressure and total breakdown pressure of the models are also different. The larger the BP spacing, the higher the compressive strength of the BP, and a larger reduction ratio (the ratio of the strength parameters of the BP to the strength parameters of the matrix) leads to a smaller impact of the BP on fracture initiation and propagation. The elastic modulus has no effect on the failure mode of the model. When HF make contact with the BP, they tend to extend along the BP. Under the same in situ stress condition, the presence of a BP makes the morphology of HF more complex during the process of propagation, which makes it easier to achieve the purpose of stimulated reservoir volume (SRV) fracturing and increased production.

Oxygen and carbon dioxide permeability of subcutaneous pockets

1962 ◽  
Vol 202 (1) ◽  
pp. 53-58 ◽  
Author(s):  
Hugh D. Van Liew
Keyword(s):  
Carbon Dioxide ◽  
Blood Flow ◽  
Surface Area ◽  
Uptake Rate ◽  
Permeability Coefficient ◽  
Exchange Coefficient ◽  
Adjacent Tissue ◽  
Permeability Coefficients ◽  
Tissue Tension

Uptake rate of a gas from a rat's subcutaneous gas pocket was divided by the surface area and by the apparent pocket-to-tissue tension difference to yield an exchange coefficient, K'. Values in (ml x 10–4)/(min cm2 atm) were O2, 6.6; CO2, 150; and N2, 2. Blood flow in adjacent tissue appeared to have little influence on uptakes of O2 and CO2, since the K'co2:K'o2 ratio indicated that the uptakes were governed by diffusion alone, and drastic alteration of blood flow (death of the animal) decreased K'o2 by only 10%. In contrast, blood flow apparently affected N2 uptake. Because O2 and CO2 uptakes were not blood flow limited, K'o2 and K'co2 are estimates of true permeability coefficients; the calculated permeability coefficient for N2 is 3.3 (ml x 10–4)/(min cm2 atm). Comparison shows the pocket surface to be 1/50–1/150 as effective for O2 transfer as the lung. Finally, corrections are calculated for pocket-to-tissue pO2 and pCO2 differences in gas pockets used for tissue tonometry.

scholarly journals Test on Compaction Reinforcement Effect of Sand

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Lianzhen Zhang ◽  
Qingsong Zhang ◽  
Zhipeng Li ◽  
Hongbo Wang
Keyword(s):  
Permeability Coefficient ◽  
Clay Content ◽  
Compression Modulus ◽  
Sand Layer ◽  
Reinforcement Effect ◽  
Initial Water ◽  
Grouting Pressure ◽  
Performance Indexes ◽  
The Relationship ◽  
Water Ratio

In fracture or compaction grouting projects of sand layer, there exist many compacted sand regions on both sides of grout veins or around grout bulbs. It has an important effect on the final reinforcement effect of the sand layer that how much performance of the sand layer is improved after being compacted. Compression modulus, cohesion, and permeability coefficient are selected to be the performance indexes of the compaction reinforcement effect of sand. The relationship between the performance properties of sand and grouting pressure has been tested and analyzed. And influences of clay content and initial water ratio of sand on the compaction reinforcement effect have been studied. Results show that compaction can effectively improve the mechanical properties and impermeability properties of sand. Compression modulus of sand increases by 2∼18 times. The cohesion of sand increases from the scope of 9.4∼26 kPa to the scope of 40∼113.6 kPa. The permeability coefficient of sand decreases from the scope of 1.0 × 10−2∼ 8.33 × 10−4 cm/s to the scope of 2.19 × 10−4∼2.77 × 10−9 cm/s. When the clay content of sand is smaller than about 20%, sand cannot be reinforced effectively by compaction. Cohesion cannot be improved significantly and the permeability coefficient cannot be reduced markedly. A high initial water ratio of sand is beneficial to improve the compression modulus of compacted sand and goes against the improvement of cohesion of compacted sand. In addition, the initial water ratio has little effect on the permeability coefficient of compacted sand. In the end, fitting formulas have been developed to quantitatively describe the compaction reinforcement effect of sand by different grouting pressures.

scholarly journals Stability Analysis of Hydrodynamic Pressure Landslides with Different Permeability Coefficients Affected by Reservoir Water Level Fluctuations and Rainstorms

Water ◽  
2017 ◽  
Vol 9 (7) ◽  
pp. 450 ◽  
Author(s):  
Faming Huang ◽  
Xiaoyan Luo ◽  
Weiping Liu
Keyword(s):  
Water Level ◽  
Permeability Coefficient ◽  
Hydrodynamic Pressure ◽  
Water Level Fluctuations ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Stability Coefficient ◽  
Permeability Coefficients ◽  
Landslide Stability ◽  
The Stability

It is significant to study the variations in the stability coefficients of hydrodynamic pressure landslides with different permeability coefficients affected by reservoir water level fluctuations and rainstorms. The Sifangbei landslide in Three Gorges Reservoir area is used as case study. Its stability coefficients are simulated based on saturated-unsaturated seepage theory and finite element analysis. The operating conditions of stability coefficients calculation are reservoir water level variations between 175 m and 145 m, different rates of reservoir water level fluctuations, and a three-day continuous rainstorm. Results show that the stability coefficient of the hydrodynamic pressure landslide decreases with the drawdown of the reservoir water level, and a rapid drawdown rate leads to a small stability coefficient when the permeability coefficient ranges from 1.16 × 10−6 m/s to 4.64 × 10−5 m/s. Additionally, the landslide stability coefficient increases as the reservoir water level increases, and a rapid increase in the water level leads to a high stability coefficient when the permeability coefficient ranges from 1.16 × 10−6 m/s to 4.64 × 10−5 m/s. The landslide stability coefficient initially decreases and then increases as the reservoir water level declines when the permeability coefficient is greater than 4.64 × 10−5 m/s. Moreover, for structures with the same landslide, the landslide stability coefficient is most sensitive to the change in the rate of reservoir water level drawdown when the permeability coefficient increases from 1.16 × 10−6 m/s to 1.16 × 10−4 m/s. Additionally, the rate of decrease in the stability coefficient increases as the permeability coefficient increases. Finally, the three-day rainstorm leads to a significant reduction in landslide stability, and the rate of decrease in the stability coefficient initially increases and then decreases as the permeability coefficient increases.

Predicting of Permeability Coefficient for Compacted Clay

2013 ◽  
Vol 405-408 ◽  
pp. 571-575
Author(s):  
Dong Qin Ran ◽  
Ji Ru Zhang
Keyword(s):  
Analytical Method ◽  
Permeability Coefficient ◽  
Compacted Clay ◽  
Water Release ◽  
Permeability Coefficients ◽  
Nonlinear Trend

Permeability coefficients of three compacted clay samples are measured by using Transient Water Release and Imbitions Method which is shortly named as TRIM. The curve between permeability coefficient and suction is obtained, the results of tests show that the permeability coefficient decreases in nonlinear trend along with the increasing of suction. Based on Brooks Corey model and Mualem model which is shortly named as BCM model, an analytical method is put forward to calculate the permeability coefficient of compacted clay. The results of using BCM model and TRIM are compared, which show that the permeability coefficient obtained with two kinds of methods match well when the suction is greater than the inlet value.

scholarly journals Investigation of soils of stubbles of winter wheat and winter peas in conventional and reduced tillage systems

2016 ◽  
pp. 95-99
Author(s):  
Géza Tuba ◽  
Györgyi Kovács ◽  
József Zsembeli
Keyword(s):  
Winter Wheat ◽  
Carbon Dioxide Emission ◽  
Soil Layer ◽  
Clay Content ◽  
Weather Conditions ◽  
Vegetation Period ◽  
Conventional Tillage ◽  
Reduced Tillage ◽  
Tillage Systems ◽  
Positive Effects

The effect of reduced and conventional tillage on soil compaction, soil moisture status and carbon-dioxide emission of the soil was studied on a meadow chernozem soil with high clay content in the soil cultivation experiment started in 1997 at Karcag Research Institute. Our investigations were done on stubbles after the harvest of winter wheat and winter peas after the very droughty vegetation period of 2014/2015. We established that the soil in both tillage systems was dry and compacted and the CO2-emission was very low. The positive effects of reduced tillage could be figured out only in the soil layer of 40–60 cm in the given weather conditions of that period.

scholarly journals Geological criteria for waste disposal site selection: a case study from Kanichadar, Dhangarhi, Far Western Nepal

2002 ◽  
Vol 27 ◽  
Author(s):  
Lila Nath Rimal ◽  
Bharat M. Jnawali ◽  
Surya Prakash Manandhar
Keyword(s):  
Soil Layer ◽  
Chemical Properties ◽  
Suitable Condition ◽  
Exchange Capacity ◽  
Landfill Site ◽  
Disposal Site ◽  
Sanitary Landfill ◽  
Clay Layer ◽  
Clayey Silt ◽  
Organic Clay

Proper management of municipal solid waste in an environmentally friendly way needs first-hand knowledge of site geology. A clay layer (i.e. geological barrier) of sufficient thickness and extension beneath the surface is a suitable condition for a sanitary landfill site. The clay layer acts as a natural barrier against the migrating pollutants originating from leachate into the ground. The leachate generated at the landfill site can pollute the groundwater in absence of such geologic barrier. The Kanichadar area is underlain by about 3 m thick fine-grained soil. The topmost soil layer is 20-50 cm thick dark brown organic clay. There is a highly compact, dark brown and dry inorganic clayey silt layer of more than 1.5 m thickness below the organic clay layer. Soil samples collected from different Auger holes were subjected to laboratory analysis to determine their physical and chemical properties. The values thus obtained indicated that the soil belongs to 'CL' type, implying that the soil is inorganic clay of low to medium plasticity. However, the hydrometer analysis showed that the samples were of clayey silt. The cation exchange capacity (CEC) values obtained from the depth of 0.5-2.30 m revealed that the soil had moderate to high barrier potential for attenuation of the migrating pollutants. Therefore, the area close to these auger holes was found to be suitable for sanitary landfill.

scholarly journals Effects of percolating water with graduated acidity upon the leaching of nutrients and the changes in some chemical properties of mineral soils

1977 ◽  
Vol 49 (4) ◽  
pp. 250-257
Author(s):  
František Haman
Keyword(s):  
Soil Layer ◽  
Chemical Properties ◽  
Clay Content ◽  
Fine Sand ◽  
Three Solutions ◽  
Clay Particles ◽  
Plastic Bags ◽  
Water Ph ◽  
Mineral Soils ◽  
Basic Cations

Leaching of nutrients and the changes in some chemical properties of surface soil layer treated with solutions of gradual acidity were followed under laboratory conditions. The 25-cm-high columns of three soils, (A – fine sand, B - loam, C - clay loam), placed in plastic tubes were treated with deionized water (pH 6) and with three solutions (pH 5, pH 4, pH 3) of sulphuric acid. The washed out were determined in the leachates collected into plastic bags. The largest amount of nitrogen found in the leachates was in the form of nitrate and this was proportional to the content of organic matter in the soils. The leached amount of NH4-N was considerably lower and like potassium it was negatively dependent upon the clay content in the soils. The concentrations of K, Ca and Mg in the leachates rose in relation to the declining pH of percolating solutions. Especially in soil A, acid solutions of pH 5 (and lower) washed out very effectively the cations. Soils Band C (with a higher content of clay particles) showed a higher resistance to K, Ca and Mg leaching. The acidified water influenced even the pH of the surface layer (0—7,5 cm) of soils in the columns. The most marked decrease in pH values was found in soil A after an application of the solution with pH 3. A decrease in the content of basic cations (Ca and Mg) was parallel to the acidification of the upper layer of the soils.

scholarly journals Soil Disintegration Characteristics of Collapsed Walls and Influencing Factors in Southern China

2018 ◽  
Vol 10 (1) ◽  
pp. 797-806
Author(s):  
Hongyi Zhou ◽  
Huixia Li
Keyword(s):  
Water Content ◽  
Correlation Coefficient ◽  
Sandy Soil ◽  
Soil Layer ◽  
Chemical Properties ◽  
Soil Samples ◽  
Red Soil ◽  
Physical And Chemical Properties ◽  
Physical And Chemical ◽  
And Chemical Properties

Abstract Collapsed walls cause collapsed mounds, and the disintegration characteristics of collapsed walls are thus closely linked with the occurrence of collapsed mounds. The current study examines the disintegration characteristics and the physical and chemical properties of collapsed walls. A multilevel analysis was conducted by obtaining soil samples from four layers of a collapsed wall. The results showed that 1) the physical and chemical properties of the soil samples (red soil layer, sandy soil layer, debris layer, gravel and eluvial breccia) are closely related to the weathering degree of the crust; 2) gravel and eluvial breccia disintegrated in the shortest time, whereas red soil exhibited the slowest disintegration in the vertical section of the collapsed wall. The order of the disintegrating ratio of the layers is as follows: red soil layer < sandy soil layer < debris layer < gravel and eluvial breccia. Initial water content significantly influenced the disintegration ratio of the red soil layer and sandy soil layer, whereas its effect on the debris layer and gravel eluvial breccia is minimal; and 3) most of the physical and chemical properties of the collapsed wall are significantly correlated with the disintegration ratio of the soil sample. The following physical and chemical properties, which are positively correlated with the disintegration ratio, are arranged based on highest to lowest correlation coefficient: sand content, MgO, natural water content, K2O, CaO, exchangeable sodium, pH, porosity, Na2O, and cation exchange capacity. The following physical and chemical properties, which are negatively correlated with the disintegration ratio, are organized based on highest to lowest correlation coefficient: cosmid, Fe2O3, silt particle, Al2O3, TiO2, SiO2, organic matter, free iron oxide, and free alumina. Only exchangeable calcium, saturated water content, specific gravity of soil particles, and dry density of soil particles are significantly correlated with the disintegration ratio. The correlation coefficient indicates that the disintegration ratio and soil structure, as well as the chemical content of clay minerals, are closely correlated. The study helps explain the mechanism of wall collapse and provides references for developing protective measures against erosion.

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