SOIL MECHANICS BOOKS BY BC PUNMIA DOWNLOAD FREE
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short description about the book
Formation of soils - types of soils - classification of soils for engineering practice - Field identification of soils - Physical properties of soils - Three phase diagram - permeability characteristics of soils - stress distribution in soils - Theory of consolidation, shear strength parameters of soils - Compaction of soils.
Soil exploration - Soil sampling techniques - Borelog profile - shallow foundations - Terzhagi's bearing capacity theory - Pile foundation - Group action of piles - settlement of foundations.
SOIL DEFINTION
According to an agricultural scientist, Soil is defined as the loose material on the earth's crust consisting of disintegrated rock with an admixture of organic matter, which supports plant life.
According to a geologist, Soil is defined as the disintegrated rock material which has not been transp¬orted from the place of origin.
According to a civil engineer, Soil' is defined as the loose unconsolidated inorganic material on the earth's crust produced by the disintegration of rocks, overlying hard rock with or without organic matter.
INDEX PROPERTIES OF SOIL :
The properties of soils which are not of primary interest to the geotechnical engineer but which are indicative of the engineering properties are called index properties.
MECHANICAL ANALYSIS
The mechanical analysis is also known as particle size analysis. It is a method of separation of soils into different fractions based on the particle size. The purpose of Particle Size Analysis ( Mechanical Analysis ) is to determine the percentage of various sizes of particles in a soil sample.
The mechanical analysis is done in two stages.
1) Sieve Analysis
2) Sedimentation Analysis
Sedimentation analysis or Wet mechanical analysis
Sieve Analysis is meant for coarse-grained soils having particles with size greater than 75 micron. Sedimentation analysis is used for fine-grained soils (size smaller than 75 micron ). Sedimentation analysis is also known as wet analysis. Any soil mass may contain the particles of both types of soils, a combined analysis comprising both sieve analysis and sedimentation analysis may be required for any soil mass.
Any soil sample may be classified as
i) Well graded soil
ii) Poorly graded soil ( Uniformly Graded Soil )
Water present in the voids of a soil mass is called soil water. The soil water is broadly classified into two categories:
1) Free water
2) Held wader
Classification on phenomenological basis
1) Ground water
2) Capillary water
3) Adsorbed water
4) Infiltered water
Classification on structural aspect
1) Pore water
2) Solvate water
3) Adsorbed water
4) Structural water
FREE WATER
Free water moves in the pores of the soil under the influence of gravity. Free water flows from one point to the other wherever there is a difference of total head. The rate at which the head is lost along the flow passage is equal to the hydraulic gradient.
HELD WATER
The held water is retained in the pores of the soil and it cannot move under the influence of gravitational force. Held water is further divided into three types.
1) Structural water
2) Adsorbed water
3) Capillary water
STRUCTURAL WATER
The structural water is chemically combined water in the crystal structure of the mineral of the soil. This water cannot be removed without breaking the structure of the mineral. A temperature of more than 300°C is required for removing the structural water. In soil engineering, the structural water is considered as integral part of the soil solid.
ADSORBED WATER ( Contact Moisture / Surface Bound Moisture )
The water held by electrochemical forces existing on the soil surface is known as adsorbed water. The quantity of adsorbed water depends upon the colloidal fraction in the soil, chemical composition of the clay mineral and the environment surrounding the particle. The adsorbed water is important only for clayey soils. For coarse grained soils, its amount is negligible or zero.
Adsorbed water comprises of
i) hygroscopic water
ii) film Moisture
Hygroscopic water or contact moisture or surface bound moisture is that water which soil particles freely adsorb from atmosphere by the physical forces of attraction at held by the forces of adhesion. This form of moisture is in a dense state and surrounding the surfaces of individual soil grains as a very thin film.
Film moisture is attached to the surface of soil particles as a film on the layer of hygroscopic film. This film forms because of condensation of aqueous vapour. Film moisture is also held by molecular forces of high intensity but not as high as in the case of hygroscopic film. Film moisture can migrate on the application of external energy potential (i.e. thermal potential or electric potential). The greater the specific surface soil, the more is the film moisture that can be contained.
CAPILLARY WATER
It is that water which is lifted up by surface tension above free ground water surface. This water is in suspended condition within the interstices pores of capillary size of the soil. The capillary water fills all the pores to a certain distance above the water table - this distance being known as zone of saturation.
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