Introduction
Soil mechanics site investigations are conducted to discover the characteristics of the soil at the particular location. The foundation is the lowest part of a building. It transmits the load of the structure to the soil below. The main purposes of a foundation is to take the structure sufficiently deep into the ground to prevent overturning before a foundation is decided, it is necessary to determine the characteristics of the soil at the site of construction. This is done by conducting soil investigations. A standard penetration test is an in-situ dynamic penetration test designed to provide information on the properties of soil, while also collecting a disturbed soil sample for grain-size analysis and soil classification.
Method
Standard Penetration Test (SPT) is used because of it's simplicity and low cost. It can provide useful information in very specific types of soil conditions. The standard penetration test is conducted in a bore hole using a standard split spoon sampler. When the bore hole has been drilled to the desired depth, the drilling tools are removed and the sampler is lowered to the bottom of the hole. The sampler is driven into the soil by a drop hammer of 63.5 kg mass falling through a height of 750 mm at the rate of 30 blows per minute. The number of hammer blows required to drive 150 mm of the sample is counted. The sampler is further driven by 150 mm and the number of blows recorded. Likewise, the sampler is once again further driven by 150 mm and the number of blows recorded. The number of blows recorded for the first 150 mm is disregarded. The number of blows recorded for last two 150 mm intervals are added to give the standard penetration number (N).
Purpose
The main purpose of the standard penetration test (SPT) is to provide an indication of the relative density of granular deposits, such as sands and gravels from which it is virtually impossible to obtain undisturbed samples. The great merit of the test, and the main reason for its widespread use is that it is simple and inexpensive. The soil strength parameters which can be inferred are approximate, but may give a useful guide in ground conditions where it may not be possible to obtain borehole samples of adequate quality like gravels, sands, silts, clay containing sand or gravel and weak rock.
Laboratory testing
We have a fully-fledged geotechnical laboratory with facilities for testing samples collected from site. Our laboratory team members are well-trained to handle the state-of-art testing equipment. We are committed to providing reliable and accurate test results to our customers, along with technically correct interpretations.
We have in-house facilities to carry out the following laboratory tests:
- Laboratory Testing
- Grain Size Analysis & Hydrometer
- Moisture Content and Density
- Specific Gravity
- Atterberg Limits & Shrinkage Limit
- Swell Index
- Swelling Pressure
- Direct Shear Tests
- Permeability
- Unconfined Compressive Stength (UCS)
- Triaxial test
- Standard and Modified Compaction Tests
- California Bearing Ratio (CBR)
- Consolidation
- Unconfined compressive strength (Crushing Strength)
- Point load test
- Brazilian test
- Hardness (Mohs Scale)
We provide following services of geotechnical consultancy to our clients:
Calculation of Bearing capacity of Soil and Settlement of Foundation Design of foundation for different sub-soil conditions Slope-Stability Analysis for Embankments, Dams, Retaining-Walls etc.
Images Contained:
- In-house testing machines:
- Direct shear machine
- Triaxial testing machine
- Hydrometer test
- Sieves
- CBR test machine
- Consolidation test equipment
Site machines
- 1. SPT test machine