Soils specimens

There is a direct and an indirect method of measuring specific soil resistivity. The direct method is carried out in the laboratoiy on a soil sample using a soil box as shown in Fig. 3-16. The resistivity of a soil specimen of cross-section, S, and length, I, is measured and the specific resistivity determined ... 

Bottom soil is quite different from soil on land, particularly if it is collected from an anaerobic zone. Bottom soil specimens also have varying composition. The presence of elementary sulphur and organic compounds of sulphur greatly complicates analysis of the residual organochlorine... 

Acar et al. (1996 1997) showed that ionic migration could be used for injection and transport of anionic and cationic additives. In a bench-scale experimental setup, ammonium hydroxide (NH4OH) was introduced at the anode compartment and sulfuric acid (H2S04) at the cathode compartment. The electric field caused migration of nitrate ion from anode towards the cathode and sulfate ion from cathode towards the anode. The study reported transport rates of 5 to 20 cm/day in fine sand and kaolinite soil specimens and consequent soil saturation of ammonium and sulfate ions. The study concluded that ion migration under dc fields can be used to inject nutrients, electron acceptors/donors to enhance in situ bioremediation. 

Figure 1.2 Contact traces of yellowish-gray soil on the suspect s shoes (left) and the control soil specimen from the bank of a river (right), which comprises a mixture of 95% coarse gravel and rock fragments and only 5% clay and silt (< 50 pm fraction). (See color insert following p. 178.)...

The available literature clearly shows that fungi are present in even the deepest sediments of the sea, and therefore could potentially be buried with sediments. Little is known about marine filamentous fungi and yeasts, and almost nothing about their life-cycles or metabolism under deep-sea and sub-sea-floor conditions. If they survive burial, they will eventually become part of the sub-sea-floor biosphere. No direct data describe how long fungi can survive in subsurface environments. Data from dried soil specimens indicate that fungi survive fewer than 50-100 years separated from their autochthonous surface environment (Sneath, 1962). However, sub-sea-floor conditions may very well be more favourable for preservation than are soil conditions. 

In general, the electroremediation of heavy metals and metalloids in Table 4.1 are dependent mainly on the development of an acidic front through the soil since the acidification aids mobilization. In most of the experiments, the acidification had not reached through the whole soil specimen during the remediation period, and the remediation percentages given in the table were obtained only in a short distance from the anode. 

Moreno, L., Mills, D., Entry, J., et al.. Microbial metagenome profiling using amplicon length heterogeneity-polymerase chain reaction proves more effective than elemental analysis in discriminating soil specimens, J Forensic Sci, 51, 2006. 

La Rochelle, P, Sarraith, Roy, M., and Tavenas, F. 1976. Effect of Storage and Reconsolidation on the Properties of Champlain Clays. Soil Specimen Preparation for Laboratory Testing. STP 599. American Society for Testing and Materials, Philadelphia, PA, pp. 126-146. 

Silt content affects the c values through its influence on m and hydraulic conductivity k. For the same sand-silt mix at different proportions of silt content, m appears to be influenced by equivalent intergranular void ratios (Figure 6a-b). Hydraulic conductivity is affected by both void ratio and silt content. Silt content has a significant effect on k than the influence of void ratio on k. Hydraulic conductivity of the soil specimens in this study ranged from 0.6 to 1.3x10 cm/s for the clean sand, 9x10 cm/s for 15% silt content. 

The value of Go can be determined measuring the speed of artificially generated shear waves on the site, by laboratory measurements on soil specimens or... 

The moist specific gravity of the compacted soil specimen (p ,) is calculated using the relationship... 

The device consists of a metal mould (100 mm in diameter and 200 mm in height) and a rammer (97 mm in diameter and 7 kg in mass), which drops from a standard height of 250 mm on the soil specimen surface. 

After the initial load application, the rammer falls freely on the soil specimen, and after a predetermined number of blows, the penetration of the rammer is measured. The process is carried out repeatedly until no additional rammer penetration is observed. On completion, the soil sample is taken for redetermination of the moisture content. 

After compaction and once the metal extension collar is removed, the soil material is flattened by means of a straightedge (knife or spatula) until it is even with the top of the mould. Afterwards, the soil specimen with the steel mould is inverted and clamped on a perforated base plate (a coarse filter paper is added to the interface of the perforated base plate and soil specimen). Sufficient annular weights (usually three) are added on the compacted soil material in the mould in order to produce a surcharge equal to the weight of the overlying layers. Soil material, mould and surcharge weights are immersed in water (water level shall be 25 mm above the specimen s surface). At the same time, a tripod with a dial indicator is placed over the mould and its initial indication is recorded. The whole system remains undisturbed for 96 h. 

At the end of the 96 h and after the last indication has been recorded, the whole system is removed from the water bath. The tripod and the surcharge weights are removed and the specimen is allowed to drain downwards for 15 min. After this time, the compacted soil specimen is ready for the CBR determination test. From the measurements of the dial indicator (first and last indication), the swell (as a percentage of the initial height of the specimen) of the soil material is determined. 

Loading Metal rings Mould extension ring Soil specimen Steel mould Steel spacer... 

The deviator stress Oa (=Oi - 02) is repeated, at a fixed magnitude and frequency. The loading of the soil specimen, under the influence of deviator stress, results in a deformation, part of which is recoverable during the stage of unloading. This recoverable strain along with the deviator stress determines the resilient modulus (Mr), or the modulus of elasticity ( ), of the material tested, using the equation... 

The compaction of the soil specimens is carried out by either the double plunger method or the kneading compactor and the specimen is tested at maximum density. The test can also be carried out in undisturbed specimens extracted from the site. 

Some specific problems undertaken include location of heavy metals in soil specimens due to application of sewage sludge, trace element profiling in electrical insulators, analysis of air particulate collected at urban locations, multilayer thin film analysis of solar cells. 

The biaxial compression tests were carried out on the small scale soil specimens under 100 kPa, 200 kPa, 300 kPa respectively to calculate the macro-mechanical parameters of soil. Figure 2 shows the sample before and after the biaxial compression with confining pressure equals 300 kPa. Through comparison the ballooning effect can be seen obviously that the axial compression... 

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