Geotechnical engineering is the branch of civil engineering concerned with the engineering behavior of earth materials. Geotechnical engineering is important in civil engineering concerned with construction on or in the ground. Geotechnical engineering uses principles of soil mechanics and rock mechanics to investigate subsurface conditions and materials; determine the relevant physical/mechanical and chemical properties of these materials; evaluate; assess risks posed by site conditions; design earthworks and structure foundations; and monitor site conditions, earthwork and foundation construction.
Soil, one of the major part of is the loose surface material consisting of inorganic particles and organic matter that covers most of the land surface. Soil provides the structural support and the source of water and nutrients for plants used in agriculture. Soil makes up the outermost layer of our planet. Topsoil is the most productive soil layer.
Mainly 5 size fractions are used to describe the inorganic part of the soil i.e. Gravel, Coarse Sand , Fine Sand, Silt & Clay . The proportion of these components determines if a soil is a sand, loam or clay or any combination of these .Based upon this Texture of soil, it can be of several types :
Sand – A sand has a loose gritty feel and does not stick together. Individual sand grains can be seen or felt.
Loamy Sand – In a loamy sand particles barely stick together and a moulded piece of soil just holds its shape.
Sandy Loam – A sandy loam sticks together more than a loamy sand but can be easily broken. Individual sand grains can be felt and heard if a wet sample is rubbed between the index finger and thumb and held close to the ear.
Silty Loam – A silty loam is like a loam but has a smooth silky feel when a moist sample is pushed between the index finger and thumb. On drying a sample can form a hard lump but this may be broken by hand.
Loam – A loam breaks into crumbs but will tend to stick together. Sand grains cannot be felt in a moist sample which when squeezed will retain its shape when handled freely. Loams are usually soft to the feel.
Sandy Clay Loam – A sandy clay loam is like a clay loam but sand grains can be felt (and heard – see Sandy Loam)
Silty Clay Loam – A silty clay loam is like a clay loam but silty as well and smooth to the touch.
Clay Loam – More easily moulded into a shape than a loam, a clay loam rolls out to a thin ribbon between the palms while a loam will break-up. When dry a clay loam will form a lump but is not as tough to break as a clay.
Sandy Clay – A sandy clay is like a clay but sand grains can be felt (and heard – see Sandy Loam).
Silty Clay – A silty clay is like a clay but smoother.
Clay – Clays are tough and can be moulded into shapes when moist. Clays form a long flexible ribbon when rubbed between the palms and the ribbon can often be bent into a “U” shape without breaking. Clays dry into very hard clods.
The organic matter of soil usually makes up less than 10% by weight of soil. Plants living in soil continually add organic matter in the form of roots and debris. Decomposition of this organic matter by microbial activity releases nutrients for the growth of other plants. The organic matter content of a soil depends on the rates of organic matter addition and decomposition
JASNATH LAB provide the following soil analysis & and services:
| Physical Properties | Chemical Properties | Strength & Stability studies | Index Properties | Geo Technical Survey | Contaminants |
|---|---|---|---|---|---|
| Soil Texture | pH | Direct Shear Test | Liquid Limit | Soil Bearing Capacity | Leachability |
| Classification | Conductivity | Triaxial Strength | Plastic Limit | Plate load test (Load bearing Capacity) |
Heavy Metals |
| Compaction | Salinity | Consolidation | Plasticity Index | Standard Penetration test | Pesticides |
| Porosity | Cation Exchange Capacity | Proctor Test (OMC & MDD) | Linear & Volumetric Shrinkage | Electrical Resistivity | VOC’s |
| Permeability | Organic Matter | California Bearing Ratio (lab & Field) | Density | Dynamic Cone Penetration Test (DCPT) | |
| Water Holding Capacity | Carbon to Nitrogen Ratio | Unconfined Compressive Strength | Particle Density | Bore logging | |
| Void Ratio | Gypsum | Dry Bulk Density | Specific Gravity | ||
| Moisture | Soil Nutrients | Particle size distribution | |||
| Swelling pressure | Minerological Analysis | Sand Equivalent Value | |||
| Free Swell Index | Sedimentation | ||||
| Sodium Absorption Ratio (SAR) | Grain Size Analysis | ||||
| Uniformity coefficient |
MAJOR INSTRUMENTATION AVAILABLE AT JASNATH LAB FOR SOIL INVESTIGATIONS
• Triaxial shear Strength unit
• Direct Shear Unit
• Consolidation unit
• Soil Permeability unit
• CBR unit
• Earth Resistivity Meter
• Core Cutters for Soil compaction
• Plate load unit
• Safe bearing capacity unit with load truss
• Standard Penetration Test unit
• Grain size analyzer
• Shrinkage Limit unit
• Swell test unit
• Casagrande units
• Cone Penetrometer
• Sand Equivalent Value unit
• Soil Hydrometers
• Automatic compactors
• Compressive Strength Machines
• GC & GC – MS
• pH Metes
• Conductivity meters
• Air Ovens
• Weighing Balances
• Specific Gravity units
