Consolidation refers to the settlement or compression that soils undergo as a response of applying stress onto it. It is the time-related process of increasing the density of a saturated soil by squeezing some water out of the voids. As a result, there is a reduction in volume of soils; causing the soil particles pack together more tightly.
The compression of the soil occurs when there is an increasing of effective stress. Therefore, a pore- water pressure and a void ratio decrease when the effective stress goes up. The spring here have the same behavior as a soil skeleton. The stiffer the spring, the less it will be compressed. The stiff soil will have less compression than a soft soil. The opening size of the valve is similar to the permeability of the soil. The larger the opening, the shorter it takes for the water to flow out.
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The friction of the sample is enhanced by the boundary effect from the ring. That friction will cause a reduced stress acted on the soil during loading.
• The mechanical lever arm system will easily affect the measurement due to the sudden shock when the load is applied.
• The other limitation of this method is that no means is available for measuring the pore water pressure during testing even though the dissipation of excess pore water pressure is one of the factor control the consolidation process. Change of thickness of the specimen is the only data that used for estimating the compressibility.
• It is one-dimensional consolidation test and there is no consideration of influence of lateral stresses on deformation properties.
The predicted rates of settlement using Cv from the oedometer tests are usually less than those actual rates of settlement of site due to the influence of the soil macro –fabric on drainage behavior. For example, laminations, layers of silt and fine sand, silt – filled fissures, organic inclusion and root
• For the spacing, a consideration should be done for the depth of compressible layer, permeability of soil and location of ground water table. As well as that when compacting for deeper layers a wider spacing should be used compared to upper layers.
This is related to the blending of the fluids and rocks of the reservoir. Skeletal properties of interest to reservoir engineers include porosity, pore size distribution, compressibility, and absolute permeability of the rod. Interaction or dynamic properties of reservoir rocks are affected by the nature and by its interaction with present fluids, as...
A reservoir is considered as a compaction drive is when the pore volume contraction takes prominently to overall expansion while the reservoir is saturated. This drive is supplemented by solution gas drive and may or may not by water/gas cap drive. This reservoir acts like their non-compaction counterparts except that they exhibit enhanced recoveries. For example, the oil recovery will be greater for a solution gas drive by which the compaction drive will act like a normal solution gas drive reservoir. This is because of the direct consequence of the extra rock expansion that compaction drive reservoirs actually have. Due to the extra compaction, some production occurs. For instance, the permeability may decline, fracture may happen and subsidence but all there problems are manageable and the result of compaction is very favorable.
The interactive force between the fluid and the porous medium is due to the frictional forces only and this force proportional to the flow velocity which represents by the term , where is the Darcy's coefficient, is the fluid viscosity and is the permeability of the porous medium.
The differences seen in the soil may be due to addition of carbon/ nitrogen which can change and alter the C:N ratio. The greater C:N ratio the more extracellular polymers are released which help hold the aggregates together and better its stability. The lower the C:N ratio the worse the aggregate stability and the faster the aggregate will crumble away as can be seen in both a slaking test and the alfalfa treatment.
It is a well known fact that a good quality sample is necessary to get realistic soil parameters. Basically, preserving soil natural structure and stress condition in the laboratory sample determine the quality of soil parameters. However, many researchers pointed out that it is impossible to retain original soil condition even though we use so-called high quality sampler and same in-situ effective stress condition during the laboratory testing. On the other hand, many researchers have tried to overcome such problem of soil disturbance by introducing several methods of correcting soil parameters for poor quality sample. Moreover, recompression method and Stress History and Normalized Soil Engineering Properties (SHANSEP) method are two well known methods employed recently in geotechnical engineering practice.
Dense to very dense natural and compacted foundation soils had settled a maximum of 4inches or four-tenths of a percent of the wall height. By the comparison of the
Dispersion of fine soil particles is controlled by a similar mechanism, dispersion is directly influenced by ions adsorbed on particle surfaces, particularly clay minerals. The presence of high sodium, especially at the low salt concentration in the soil water, causes dispersion and movement of fine particles within the pores. The particles may then become lodged in smaller pores, blocking water or air.
Compaction is a densification of the soil which reduces its biological activity, permeability, porosity, and water holding capacity, while at the same time increasing the risk of erosion due to accelerated run-off (13). While some soils are naturally compacted, mechanical pressure (i.e. heavy machinery) can compact soil (13). Erosion is a natural process which is actually essential in the soil formation process, but human activities have accelerated it (7). During erosion soil particles of the fertile topsoil are removed either by wind or water (i.e. runoff), this process is irreversible and can lead to the reduction of soil productivity (7).
Porosity is the amount of air space in a soil. There are two types of
After weighing the soil, we went directly to the determining soil texture by feel test. This test was arguably the easiest of the tests. The group simply held t...
There are two important properties that determine the hydraulic conductivity: the geometry of the pore system and the intrinsic properties.
The sample that had the highest permeability was the gravel. Because the size and abundance of pores in the gravel sample, water passed through it, almost, unimpeded. The pores of the rocks that composed the gravel sample did retain 16 percent, or 8ml, of the 50ml of water used. In addition, these large pores allowed a drainage rate of .186, which was the quickest of any of the samples in this experiment. If the pores were smaller, water would permeate slower and have a higher water retention
In order to know the compressibility behavior of soil, we can make a plot of voids ratio versus log time using one dimensional consolidation tests as shown in figure 1.
As a result of this process, the mine sites "do not develop normal soil structure or support the establishment of a plant cover". Many mine sites have...