Soil testing pdf download

Repeat the test for at least four sets of value of penetration. Test procedure for the determination of plastic limit I. Mix 20 g soil passes through micron IS sieve with distilled water but in case of clayey soil, the plastic soil masses should be left for 24 hrs to ensure the uniform distribution of water.

Take about 8 g of the soil and roll it with fingers on a glass plate. The rate of rolling shall be between 80 to 90 strokes per minutes to form a 3 mm diameter.

If the diameter of the threads becomes less than 3 mm without cracks, it shows that water content is more than its plastic limit. Kneed the soil to reduce the water content and roll it again to thread. Repeat the process of alternate rolling and kneading until the thread crumbles. Collect the pieces of crumbled soil thread in a moisture content container for determination of water content.

Repeat the process at least twice more with fresh samples of plastic soil each time. Similarly, the plastic limit of soil is Flow index is 4. Plasticity index and toughness index are From cone penetration test: it is found that water content at 20 mm depth of penetration is This is 0. Hence, according to IS soil classification chart, soil is classified as CI i.

Oven: thermostatically controlled to maintain the temperature between C and C. Weighing balance:- sensitive to 0. Mercury:- clean, sufficient to fill the glass cup V. Desiccators: with any desiccating agent other than sulphuric acid. Shrinkage cups VII. Plain Plate IX. Evaporating dish X. Spatula XI.

It is used to find out the structure of soil. The greater shrinkage, more the disperse structure. It is possible to study the shrinkage behavior of undisturbed soil of natural or man-made deposits and get an idea of its structure. Because any soil that undergoes a volume change Expands or contracts with change in water content may be troublesome in like a if used for highway or railway fills, it produces a bumpy road b if a structural foundation is placed on it, produces uneven floors and or structural cracks seen c if used as backfill behind a retaining wall, produces excessive thrust against the wall, which may cause it to fail.

Volume expansion and contraction depend on period of time and both on soil type and its mineral and change in water content from the reference value water content at time of construction.

Soil shrinkage or contraction is produced by soil suction. Suction is the phenomenon which produces a capillary rise of water in soil pores above water table. Thus it is done to obtain a quantitative indication of how much volume change can occur and the amount of moisture necessary to initiate volume changes.

Shrinkage limit can be done by mercury method, wax method and sand replacement method. But here, we have followed mercury method. When the specific gravity of soil is known, the shrinkage limit may also be calculated by the following formula: ……………………………………………………………….

Take a sample weighing about gm from the thoroughly mixed portion of the material passing through micron. Place about 30gm of the soil sample in the evaporating dish and thoroughly mix with distilled water in an amount sufficient to fill the soil voids completely and to make the soil pasty enough to be readily worked into the shrinkage dish without entrapping of water required to obtain the desired consistency is equal to or slightly greater than the liquid limit; in the case of plastic soils, it may exceed the liquid limit by as much as percent.

Weight empty shrinkage dish and find the volume of shrinkage dish by pouring mercury and take weight of shrinkage dish filled with mercury. Coat the inside of the shrinkage dish with a thin layer of silicone grease or Vaseline or some other heavy grease to prevent the adhesion of soil to the dish. Fill one third of the dish with soil sample and taped on the firm base so that flow allow to flow in edges. Repeat the soil filling and tapping three times and trim the dish removing excess soil and level it.

Three dishes are prepared in same way. Weight the dish with wet soil sample and keep in oven for 24 hrs drying. Weighed again dish and dry soil Figure1: Shrinkage limit Arrangement immediately after removal from oven. Fill the glass cup with mercury and level it plain glass plate. Keep the soil pat over mercury in the cup and keep the prongs over soil pat. Press the prong plate so that soil pat goes down in the cup mercury and till no mercury is displaced by soil pat.

Release the prongs so that no mercury spill out during releasing from the cup. Remove the dish from cup and take the weight of dish and mercury after displaced by soil pat. From this we can get volume of dry soil pat. Repeat same procedure for all three soil pat. The average shrinkage ration and volumetric shrinkage are 1.

Similarly the shrinkage index of soil is 2. The volumetric shrinkage of soil is higher, it means, the volume of soil is change due to moisture content. It will be better when test will be done by another method and comparing the result between these.

Moulds: dimension of mould height mm and inner diameter mm 2. Sample extruder 3. Weighing balances 4. Oven 5. Container: to determine water content. Steel straightedge: 30 cm in a length and having one beveled edge. Sieve: 4. Mixing tools: tray or pan, spoon, trowel and spatula 9. Metal rammer: having mass of moving part 2. The degree of compaction of a given soil is measured in terms of its dry density.

The dry density is maximum at the optimum water content. A curve is drawn between the water content and dry density to obtain the maximum dry density and optimum water content. Compaction method cannot remove all the air voids and therefore, the soil never becomes fully saturated.

Thus the theoretical maximum dry density is only hypothetical. The line indicating theoretical maximum dry density can be plotted along with the compaction curve. Fill the mould with soil sample prepared in three layers and each layer is given 26 blows from 2.

After each layer compaction, scrub surface of soil with spatula so that another layer bond together then keep another layer and give 25 blows. From figure it is observed that optimum moisture content OMC is OMC and dry density of soil also affect in shear strength, soil structure, permeability, void ratio etc.

Hence, these values are necessary for different civil construction work like highway, dam, embankment etc. Compression device: having load measured up to 0. Sample ejector: to prepare sample of 38 mm dia. Deformation dial gauge: with 0. Scale: to measure the dimensions of sample. Timer: to measure elapsed time. Weighting balances: specimen of gm weighed nearest to 0. Miscellaneous equipment: specimen trimming and carving tools, remolding apparatus, water content cans etc.

THEORY: The maximum load that can be transmitted to the sub soil by a foundation depends upon the resistance of the underlying soil or rock to shearing deformations or compressibility. Therefore, it is of prime importance to investigate the factors that control the shear strength of these materials. The shearing strength is commonly investigated by means of compression tests in which an axial load is applied to the specimen and increased until failure occurred. The use of compression tests to investigate the shearing strength of material depends upon the fact that failure in such tests takes place by shear on one or more inclined planes and that it is possible to compute normal pressure and shearing stress on such a plane at the instant of failure.

Thus, the unconfined compressive strength qu is the load per unit area at which the cylindrical specimen of a cohesive soil fails in compression.

In geotechnical work, it is standard practice to correct the area on which the load P is acting. One of the reasons for this area correction is to make some allowance for the way the soil is actually being loaded in the field. The original area A0 is corrected by considering that the total volume of the soil is unchanged as the sample shortens. The initial total soil sample volume is …………………………………………………………………………………………………………………………. The loss of confining pressure nearly always gives a value of Es that is too low for most geotechnical work.

For these several reasons, strain controlled test is mostly used in soil test rather than stress controlled method. The height of diameter ratio should be 2. Take two soil sample, one sample contains water content of dry side and other contain water content of wet side. Compacted specimen: keep the soil overlap failure zones Sample in tube after oiling the tube, fix Sampler tube in jack by nut and bolt.

Tightened one side completely and other side upto 76 mm left. Measure length, diameter and weight of sample and placed on the bottom of the loading device.

The upper plate should be adjusted to make contact with the specimen. Record the force and deformation reading at suitable interval. Compress the sample until failure surfaces have definitely developed or the stress-strain curve is well past its peak.

Keep the sample for water content and done same process of other sample. But from this test we can found approximate value of modulus of elasticity because it gives too low value than actual. The value obtained is From this test, it is also known that the soils which have less water content than OMC, brittle failure is occurred but soil specimen having water content more than OMC is failed by bulging.

It may be due to soil at dry side of optimum is flocculated structure. In flocculated structure soil, if we apply load, after sometimes it collapses suddenly. But soils in wet side have dispersed structure, so it takes more load than flocculated structure and fails by bulging. Which, we can see from above sketch.

This test is one of the simplest and quickest tests used for determination of shear strength of cohesive soils. The test results provide an estimate of the relative consistency of the soil.

This unconfined compressive and undrained shear strength parameters are used to calculate bearing capacity of soil, shear strength and settlement calculation of soil. Almost used in all geotechnical engineering designs e. This is quick test to obtain the shear strength parameters of cohesive fine grained soils either in undisturbed or remolded state. The test is not applicable to cohesion less or coarse grained soils.

Hence the test is representative of soils in construction sites where the rate of construction is very fast and the pore waters do not have enough time to dissipate. Moulds with base plate, stay and wing mm Length and mm Dia. Collar 3. Spacer disc 4. Metal rammer 5. Weights 6. Loading machine: capacity of Kg with movable head and base that travels at uniform rate of 1. Penetration plunger: 50 mm diameter. Dial gauges 9.

Sieves: 4. Miscellaneous Apparatus: mixing bowl, straightedge, measuring scale, soaking tank, drying oven, filter paper, dishes and calibrated measuring jar.

The California bearing ratio test usually abbreviated as CBR test is an ad hoc penetration test developed by the California State Highway Department of USA for the evaluation of Subgrade strengths for roads and pavements.

The results obtained by these tests are used in conjunction with empirical curves based on experience for the design of flexible pavements.

California bearing ratio is defined as the ratio of force per unit area required to penetrate a soil mass with a circular plunger of 50 mm diameter at the rate of 1. The load penetration curve is shown in figure 1. The curve shown in figure will be mainly convex upwards although the initial portion of the curve may be concave upwards due to surface irregularities.

A correction shall then be applied by drawing a tangent to the upper curve at the point of contraflexure. The corrected curve shall be taken to be this tangent plus the convex portion of the original curve with the origin of strains shifted to the point where the tangent cuts the horizontal strain axis as shown in figure 1. After corrected load value shall be taken from the load penetration curve, California bearing ratio calculated as: …………………………………….

The CBR values are generally calculated for penetration of 2. If the CBR value corresponding to a penetration of 5mm exceeds that for 2. If identical results follow, the bearing ratio corresponding to 5mm penetration shall be taken for design.

Reverse the mould and clamp it with base plate, keep filter paper and surcharge weight of 4. In case of soaked test submerge the sample in water for 96 hrs, remove the sample from water and the specimen is allowed to drain down water for 15 minutes, record the mass of sample. Placed the plunger seated under a load of 4 kg so that full contact is established between the surface of the specimen and the plunger. Take soil sample at 30 mm below from the top for determination of water content.

The density of soil sample for unsoaked is The results obtained by these tests are used with the empirical curves to determine the thickness of pavement and its component layers. This is the most widely used method for the design of flexible pavement.

Permeability device: 55 mm height and 80 mm diameter 2. Timer 3. Thermometer 4. Ring stand with test-tube clamp or other means to develop a differential head across soil sample 5. Buret to use with ring stand or other means of support as a standpipe.

Miscellaneous apparatus: IS sieves 4. THEORY: The coefficient of permeability is a constant of proportionality relating to the ease with which a fluid passes through a porous medium. Two general laboratory methods are available for determining the coefficient of permeability of a soil directly.

These are constant head and falling head method. I The corresponding flow rate or quantity per unit time is ……………………………………………………………………………. The constant head test is usually used for cohesionless materials and falling head test is usually used for cohesive materials. The coefficient of permeability k can be determined by following formula: For constant head method, ……………………………………………. Take the soil sample passing through 4. Mix water thoroughly.

Clean permeability device, measure the size of device. Keep porous stone and filter paper at bottom. Fill soil sample and compact sample by using static compaction. Measure length of sample and keep filter paper and porous stone at top.

Prepared specimen is connected with through the top inlet to selected stand pipe and marks the initial head and final interval at difference of 20 cm, 20 cm and 10 cm. Open bottom outlet and the time interval required for the water level to fall from a known initial head to a known final head as measured above the center of the outlet are recorded.

Refilled the stand pipe with water and the test repeated till three successive observations give nearly same time interval; the time interval being recorded for the drop in head from the same to final values. Measure x-sectional area of buret which is used as stand pipe pipe. Also, from graph plotted between height of fall and coefficient of permeability, it is shown that as increases in fall height of fluid to soil mass, coefficient of permeability also increases.

Reasons for this are varied but the major ones are as follows: 1. The soil in the permeability device is never in the same state as in the field- it is always disturbed to some extent. Orientation of the in situ stratum to the flow of water is probably not duplicated. This is impossible to duplicate in the sample-even where the void ratio may be duplicated by careful placement and compaction.

Conditions at the boundary are not the same in laboratory. The smooth wall of the permeability mold make for better flow paths than if they are rough. If the soil is stratified vertically, the flow in the different strata will be different, and this boundary condition may be impossible to reproduce in the laboratory.

The hydraulic head h is usually 5 to 10 times larger in the laboratory test than in the field. The high laboratory head may produce turbulent skin. The effect of entrapped air on the laboratory sample will be large even for small air bubbles since the sample is small. Dewatering and drainage of excavations, backfills and subgrades; 2.

Determining yield of water bearing strata; 3. The point where the vertical lines cross the X-axis was prepared using oxen plow. Data from 20 sites for fertilizers were broadcast. The trial was conducted in each crop and all treatment with their replications were used completely randomized block design RCBD in three for such analysis. Economic Analysis was applied uniformly for all plots.

Seeds were economic feasibility of the treatments. Partial budget analysis sown using a seed rate of kg ha-1 in a plot size of 5 m x was done to identify economical feasibility among different 4 m 20m2 by broadcasting.

Fertilizers were applied based Nitrogen level fertilizer rate for bread wheat crop production. Similarly, after 21 days of planting, composite soil 2.

Agronomic Data Collection samples were taken at 20 cm depth using auger for each During the different growth stages of the crop, all treatment and replications separately and the sample were necessary field management practices were carried out as per subjected to laboratory analysis using Olsen Method to the practice followed by the farming community.

Grain yield were analyzed using R software program. Determination of P-requirement Factor Pf Based on P laboratory analysis result of post planting soil 3. Result and Discussion samples available P values in samples collected from unfertilized and fertilized plots data P-requirement factor 3. The available fertilizers required per hectare to bring the level of available P content of the soil was ranged from low to extremely high P above the critical level.

Olsen et al. Phosphorus requirement factor Pf was calculated using Table 2. Initial available soil phosphorous status before planting in Degem available P values in soil sample collected and analyzed from district. Site 3 6. This was achieved by overlay of a clear plastic Site 11 The overlay was the positioned on Site 13 This result signifies that the existence of Average Nitrogen Fertilizer Determination high level fertilizer phosphorus.

Similarly, previous research output reported by Desta , Mesfin and Asnake The main effects of both N and P fertilizer were highly and Tekalign , also supports this experimental result. Table 3. P2O5 N-level Mean 0 23 46 69 92 0 Phosphorus Critical Value and P-requirement Factor The result of the study revealed that P-critical value 22 ppm figure 2 and P-requirement factor 5.

Figure 2. Critical P-concentration as determined by Cate- Nilson method. Table 4. Phosphorus Requirement factor for Bread wheat for Degem District. Marginal rate of return analysis. Soil Fertility Management ofwheat in level 3. G The Marginal rate of return were found to be range from and Mengestu Hulluka ed. Wheat Research in Ethiopia Report On area and important inputs for maintaining soil fertility and maximizing production for major crops private peasant holding meher agricultural production and productivity of the country.

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