Then porepressure ratio is equal to pore pressure coefficients B. The knowledge of pore pressure parameters is essential for the determination of effective stress from total stress. Skempton gave the pore pressure parameters which express the response of pore pressure due to changes in the total stress under undrained conditions. These parameters are used to predict pore water pressure in the field under similar condi-tions. Pore pressure coefficient A fluctuates with both the stress value and the rate of strain, due mainly to the variation of Δud with the deviator stress for a given soil.
Figure10.2: Triaxial Test Apparatus Stresses The stresses acting on a Triaxial sample during the test are as shown in Figure 10.3 From vertical equilibrium we have = The term F/A is known as the deviator stress, and is usually given the symbol . Hence we can write Figure 10.3: Stresses on a Triaxial Test Sample The axial and radial stresses are principal stresses. The object of the triaxial test is to determine the shear strength of the soil which is obtained using the Mohr-Coulomb theory. τ = c + σtanϕ 10.2 PLANNING AND ORGANIZATION 10.2.1 Apparatus and Knowledge of Equipment 1. A constant rate
LITERATURE REVIEW 2.1 General The natural soil behaves like an Expansive soil or cracking soil because these have tendency of shrinking and cracking when moisture content decreases and also have tendency of swelling when moisture content increases. The moisture may come from water leakage or sewer lines, rain, flooding. Soil generally exhibits these properties, when it contains montmorillonite clay minerals. The engineering properties of Natural soil includes plasticity characteristics, compaction properties, volume stability its strength may be enhanced by adding materials such as Rice husk ash, Sugarcane bagasse ash, cement, sodium chloride etc. The changes in properties of these soils primarily depend upon the type and amount of binder,
The process repeated again after adding suitable amount of water to the soil in an increasing order. The optimum moisture content was 14% 3.3 Soil Classification In the Indian Standard Classification System, classification of soil is done on the basis of their gradation characteristics and using Plasticity Index. Coarse grained soils that consist of more than 12% fines are classified as Silty Gravel or Silty sand if the fines are silty in character (i.e. it lies below the A-Line); They are classified as Clayey Gravel or Clayey sand if fines are clayey in character (i.e. the limits plot above the A-line on the Plasticity chart.
5.8b Compare this value with that obtained in step 3 (equation 5.7). 5.3.2 Preparation of the Sample: Dry the soil sample in a thermostatically controlled electric oven. Cool the soil sample in a desiccator. Segregate soil lumps without breaking individual particles with a rubber pestle Sieve it through the required sieve to remove undesired large particle sizes 5.3.3 Minimum Density: Weigh the mold accurately (W) Fill the mold with the representative dry soil (approximately 25 mm above the top of the mold) as loosely as possible by pouring the soil using a scoop or through a funnel in a steady stream. Spiraling motion should be just sufficient to minimize particle
COMPACTION 5. UNCONFINED COMPRESSIVE STRENGTH All these are laboratory test which conduct on soil sample individually or with combination of soil with chemicals, the percentage of used during testing is 3%, 7%, 10% of lime and 8%, 12% 16%, of sodium hydroxide. Chemical stabilizer is used for mixing of chemicals with soil in fine proportions so that during testing chemicals should be thoroughly mixed with soil as these chemicals are available in powder form or in chips form which are not easily mixed. The table shows the value of clayey soil sample of the above test: Table 1: Details of soil sample PHYSICAL PROPERTIES VALUE GRAIN SIZE DISTRIBUTION GRAVEL SAND SILT +
2.2 NUMERICAL MODEL STUDIES Constitutive models for soils are usually involving complex equations intended for predictions of the soil behaviour (Ivo Herle, 2008). Besides the objectivity function (independence of reference system and units), they should also include several essential features observed in laboratory tests of soil samples like nonlinearity, limit stress states, proportionality of stress and strain paths, irreversibility and realistic selection of state variables. Constitutive models should be useful not only to their designers, i.e. they must be also user-invariant and different users should be able to obtain same solutions. Hypoplastic numerical modelling is one of the advanced SCL based program developed by Karlsruhe University,
3.3 What is the importance of sediment for wetland? Wetlands maybe a bowl or nutrients organic compounds, metals and components of organic matter. Wetlands may also act as filters of sediments and organic matter. A wetland may be a permanent sink for these substances which compound become buried in the substrate or are released into the atmosphere, or retain them only during the growing season at under flooded conditions. The values of wetland functions related to sedimentation include water quality and erosion control.
Bioleaching, phytoremediation, composting, and biostimulation are some of the popular methods. All the above mentioned methods have been successfully implemented in different situations, but they are done over a period. This means long wait time, efforts, and investment. Today, various soil remediation equipment are used to remove contaminants from the soil. By far this is the most convenient method of remediation.
In other words, consolidation is a wring out process of ground water due to the operation of the load, which occurs as a time function because of small permeability. According to the consolidation theory of Terzaghi, consolidation consists entirely of two parts, namely: 1) Primary Consolidation Consolidation which runs due to the drainage of water from the soil so this settlement is due to in effective stress. 2) Secondary Consolidation Consolidation is still running after the primary consolidation is completed, after there is no more stress of pore water. And lasts for a long time and having small