As an advanced polymer composites electro-kinetic geosynthetics, the electro-osmotic vertical drainage (EVD) board could drain water quickly and accelerate consolidation process. However, the ...drainage rate was mainly impacted by the vertical drainage capability. Therefore, vertical drainage capability at the top of EVD board was theoretically analyzed. Basic requirements for drainage at the top of the board were summed up, as well as the formula of anode pore pressure when losing the vertical drainage capability. Meanwhile, a contrast test on the top and bottom drainage capacities was conducted. In use of the advanced EVD board, the voltage potential and pore pressure of anode were measured. Moreover, the derived formulas were verified. The result shows that the decrease of electric force gradient had an observable impact on the drainage capability. There was nearly no difference between the energy consumption for the two drainage methods. Although a little less water was discharged, the top drainage method had more advantages, such as high initial drainage velocity, few soil cracks, low anode water content and high soil strength. All of these show that the super soft soil ground could be consolidated quickly in use of the advanced EVD board through the top drainage. The top drainage method could efficiently improve the drainage effect, decrease the energy consumption and speed up the project proceeding.
Agricultural productivity in Central Asia has increased with the development of irrigation. In some regions, continual agricultural land use without adequate maintenance of drainage systems, despite ...using abundant water in the fields, has led to an increase in groundwater levels and soil salinization rate. The salinization level can be changed by controlling the groundwater level. Important countermeasures practiced in Uzbekistan include lowering high groundwater levels through open drainage, sub-surface drainage, and vertical drainage systems. Here, we report the current status and problems of these systems in Syrdarya region, Uzbekistan, which is afflicted with serious salinization issues as per field survey results and existing data. Our results clarify that the functioning of the drainage system should be monitored because (1) the bottoms of the open drainage are too undulated to allow smooth discharge, (2) some outlets of the sub-surface drainage are under drainage water level or covered with soil, and (3) the current operation style of the vertical drainage is different from the conventional one. Thus, it is important to ascertain the effects of the discharge systems in Uzbekistan.
A system of vertical drains combined with vacuum preloading is an effective method for promoting radial flow to accelerate soil consolidation. This study presents the analytical modeling of the ...consolidation of vertical drains incorporating vacuum preloading considering both vertical and horizontal drainage. The effects of a number of dimensionless parameters involving the drain length, soil permeability, and vacuum pressure are examined through average excess pore pressure, degree of consolidation, associated settlement, and time factor analyses. An analysis of selected case histories compliments the use of the proposed solutions. Design charts are also presented for practical use.Key words: analytical solution, consolidation, design charts, vertical drains.
A principle of super position of rate of settlement for two and three dimensional consolidations is introduced. Using this principle, equations for two and three dimensional consolidations are ...derived in simple and short manner. They are compared with the existing equations of (
3D
) consolidation. It is shown that they are same. In literature
3D
consolidation equation exists in polar co-ordinates only that means for radial and vertical consolidation. New equations are derived for
2D
and
3D
consolidation in
Cartesian
co-ordinates. A method of
3D
consolidation is proposed when the time or settlement at the instant of load-increment are not known. The method is applicable in step as well as (uniform and non-uniform) ramp loading. A method is suggested to obtain the time-compression data of radial and
3D
consolidation when only the vertical consolidation test is conducted and vice versa.
El-Oued Valley suffers from the problem of rising groundwater which affects agricultural and urban areas and degrades all aspects of the socioeconomic life of its inhabitants. This problem, which ...appeared in the 1980s, is primarily a result of overexploitation of deep groundwater, lack of sanitation network, and discharge of wastewater directly into the unconfined aquifer. To solve this problem, a megaproject was carried out, based on the principle of sewerage, to drain and evacuate excess water after treatment to a discharge site 70 km north of the region. In this project, the blade of groundwater above elevation of 60 m should be drained through wells of a vertical drainage system. However, the expected results have not been achieved in most affected cities, where the groundwater level continues to rise. Herein, we propose a solution to this problem, based on a new explanation of the hydrogeological structure of the unconfined aquifer that drives the rising groundwater to the surface. The main part of this research is based on interpretation of well tests carried out in wells of the vertical drainage system.
The development of dangerous hydrogeological processes takes place as a result of the action of climatic factors and of unfavourable technogenic conditions. One of the reasons of the worsening ...quality of land resources is the salination of soils by chemical compounds (chlorides, sulphides, carbonates) from ground and surface waters and the non-rational irrigation which results in worsening useful properties of soil. With the aim of decreasing or avoiding soils salination hydro-ameliorative measures are used which include the creation of drainage systems through which the removal takes place of salt solutions from salinated soils. The construction of relevant mathematical models permits to adequately describe the hydrodynamics of the filtration of underground waters and moisture transfer for solving important problems of underground hydrodynamics. With this aim the mathematical modelling was carried out of the process of salt solutions filtration and of moisture transfer in saturated-non-saturated soil mass under the action of vertical drainage system in a two-dimensional case. The computing algorithm is built for solving the set boundary problem and its programmic implementation was realized. As a result of carrying out numeric experiments the dynamics was determined of the salt transfer process taking into account processes of salt solutions filtration and of moisture transfer in saturated-non-saturated soil under the action of the vertical drainage which is urgent in using drainage in the capacity of a drainage or irrigation element in hydroameliorative systems and with the aim of improving resources of fertile soils by way of discharging salt solutions and pollutions from soil medium.
The subject of the research is one of the largest Worldâs mine tailings disposal sites, i.e. Å»elazny Most in the Legnica-GÅogów Copper Mining District (south-western Poland), where flotation ...tailings are poured out after copper ore treatment. The protective hydraulic barrier made of 46 vertical drainage wells was characterized and evaluated in view of reduction of major contaminants (Cl, Na, SO4, Ca) migrating from the facility to its foreground. The efficiency of groundwater protection was determined on the basis of a new approach. In applied method the loads of characteristic and commonly recognizable compounds, i.e. salt (NaCl) and gypsum (CaSO4) were calculated, instead their chemical components. The temporal and spatial variability of captured main contaminants loads as well as its causes are discussed. The paper ends with the results of efficiency analyses of the barrier and with respect to the predicted increase in contaminant concentrations in the pulp poured out to the tailings site.
This paper presents a case history of a geotextile reinforced highway embankment constructed on a soft estuarine deposit installed with prefabricated vertical drains. The case history documents the ...geotechnical site characterization, embankment construction, and monitoring program. The loading response of the soft estuarine soil was monitored during construction using hydrostatic profile gauges, settlement plates, pneumatic piezometers, and slope inclinometers. Settlements of up to 1.3 m were measured under the 4 m high embankment. The deformation behaviour was interpreted qualitatively from the monitoring data using the general framework of elastic-plastic soil models. The effectiveness of the monitoring program is also briefly discussed. The paper provides performance details that make this case history useful to researchers studying the loading response of soft soils under a geotextile reinforced embankment.Key words: case history, embankment, soft clay, vertical drainage, reinforcement.
Pressure fluctuation control in vertical drainage stacks has been identified as important to insure sanitary drainage performance in early empirical studies. Chaotic plumbing and over-design are ...common in utility services within building envelopes from domestic investigations in Taiwan. Considerable progress has been made in predicting the air pressure distribution within vertical drainage stacks. Following previous research, this paper focuses on an empirical approach to air pressure prediction in vertical drainage stacks. An experimental device that simulates a medium high apartment was set up to provide empirical parameters and model verification. Comparisons between the measured data and calculated values reveal that this prediction model can reproduce the mean air pressure distribution value in a vertical drainage stack given single point discharge and steady flow conditions.
Crop management models require simulation of daily soil water dynamics. The objective of this study was to develop a model to simulate the daily soil water dynamics during vertical drainage with ...reasonable accuracy using the incoming flow concept. The execution of this model, which has been developed based on the conservation of mass law, consists of two steps. First, calculating the potential daily change of soil water content (Δ
θp) for each soil layer in the profile assuming each one receives no water from the above layer. Then, calculating the actual daily change of soil water (Δ
θa) for each soil layer in the profile by adjusting Δ
θp using the incoming water flow, which can be defined as the amount of drainage water that reaches a layer in a soil profile from the above layer. The model was compared with the Suleiman and Ritchie Suleiman, A.A., Ritchie, J.T., 2004. Modifications to the DSSAT vertical drainage model for more accurate soil water dynamics estimation. Soil Sci. 169 (11), 745–757 vertical drainage model (SRVDM) and HYDRUS-1D for diverse soils and was tested using drainage experimental data of a Eutric Regosol in Bekkevoort, Belgium and a sandy soil in Georgia, U.S. The difference in Δ
θp between the new model and HYDRUS-1D for diverse soils ranged from −
0.01 to 0.016 m
3 m
−
3
for the first day and from −
0.005 to −
0.025 m
3 m
−
3
for the second day while the difference in Δ
θp between the SRVDM and HYDRUS-1D for these soils ranged from 0.014 to 0.062 m
3 m
−
3
for the first day and from −
0.01 to 0.026 m
3 m
−
3
for the second day. The relative maximum absolute errors in Δ
θa between the new model and HYDRUS-1D was 10% while the relative maximum absolute errors in Δ
θa between the SRVDM and HYDRUS-1D was 112%. In the experiments, the root mean square difference of the soil water content for the new model was lower than that for the SRVDM at the different soil depths. These results indicated that the new model outperformed the SRVDM in simulating Δ
θp and Δ
θa for diverse soil. It can be concluded that the new model was robust and reasonably accurate for diverse soils at different soil depths. The implementation of such model will improve the accuracy and applicability of regional soil water dynamics simulation and will reduce considerably the computational time and the required inputs.
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