Site investigations are performed by our geotechnical engineers or engineering geologists to obtain information on the physical properties of soil and rock around a site to design earthworks and foundations for proposed structures and for repair of distress to earthworks and structures caused by subsurface conditions.
SUB-SURFACE INVESTIGATION
Site investigations are performed by our geotechnical engineers or engineering geologists to obtain information on the physical properties of soil and rock around a site to design earthworks and foundations for proposed structures and for repair of distress to earthworks and structures caused by subsurface conditions.
Methods of observing the soils below the surface, obtaining samples, and determining physical properties of the soils and rocks include test pits, trenching (particularly for locating faults and slide planes), boring, and in situ tests. Our drilling/boring teams are trained to the highest standards to form boreholes for sampling, testing and monitoring of all types of ground for geotechnical assessment. We have performed site investigation both off-shore and on-shore in challenging conditions.
Boring
Boring and drilling is performed to go deeper into the surface and collect samples at regular intervals. We specialize in following types of drilling methods:
1) Rotary Method
2) Percussion
3) Auger
In the rotary method, the hole is drilled by a rotating bit to which a downward force is applied. The cuttings are lifted from the hole by the drilling fluid which continuously circulated down the inside of the drill string through water courses or nozzles in the bit, and upward in annular space between the drill pipe and bore hole. Rotary Method is the best method for collecting undisturbed samples. It is suitable for most kinds of soils especially fine-grained soil. It is also preferred in rock core drilling using carbide or diamond bit.
If drilling has to be executed in hard soils, possible containing layers of rubble, gravel, boulders or stones usually percussion drilling is applied. In case of percussion drilling the percussion gouges, fitted with a hardened cutting head, are driven into the soil using a percussion hammer.
An auger is a drilling device, or drill bit, that usually includes a rotating helical screw blade called a "flighting" to act as a screw conveyor to remove the drilled out material. The rotation of the blade causes the material to move out of the hole being drilled. Hand augers are usually used in the case where drilling depths are small with no water table.
Soil Samplers
Soil samples are taken using a variety of samplers; some provide only disturbed samples, while others can provide relatively undisturbed samples.
1) Split-spoon / SPT Sampler (See more about SPT TEST)
2) Shelby Tube Sampler.
3) Piston samplers.
4) Denison & Pitcher Sampler
5) Core Barrel (Single tube & Double Tube)
Types of Bits Used
* Tricon Bit 4” & 4-1/2” Dia
* Clay Bit 4-1/2” Dia
* Chopping Bit
* HX & NX Diamond Bit
* NXM Carbide Bit Bottom discharge
* NXM Carbide Bit Side discharge
Methods of observing the soils below the surface, obtaining samples, and determining physical properties of the soils and rocks include test pits, trenching (particularly for locating faults and slide planes), boring, and in situ tests. Our drilling/boring teams are trained to the highest standards to form boreholes for sampling, testing and monitoring of all types of ground for geotechnical assessment. We have performed site investigation both off-shore and on-shore in challenging conditions.
Boring
Boring and drilling is performed to go deeper into the surface and collect samples at regular intervals. We specialize in following types of drilling methods:
1) Rotary Method
2) Percussion
3) Auger
In the rotary method, the hole is drilled by a rotating bit to which a downward force is applied. The cuttings are lifted from the hole by the drilling fluid which continuously circulated down the inside of the drill string through water courses or nozzles in the bit, and upward in annular space between the drill pipe and bore hole. Rotary Method is the best method for collecting undisturbed samples. It is suitable for most kinds of soils especially fine-grained soil. It is also preferred in rock core drilling using carbide or diamond bit.
If drilling has to be executed in hard soils, possible containing layers of rubble, gravel, boulders or stones usually percussion drilling is applied. In case of percussion drilling the percussion gouges, fitted with a hardened cutting head, are driven into the soil using a percussion hammer.
An auger is a drilling device, or drill bit, that usually includes a rotating helical screw blade called a "flighting" to act as a screw conveyor to remove the drilled out material. The rotation of the blade causes the material to move out of the hole being drilled. Hand augers are usually used in the case where drilling depths are small with no water table.
Soil Samplers
Soil samples are taken using a variety of samplers; some provide only disturbed samples, while others can provide relatively undisturbed samples.
1) Split-spoon / SPT Sampler (See more about SPT TEST)
2) Shelby Tube Sampler.
3) Piston samplers.
4) Denison & Pitcher Sampler
5) Core Barrel (Single tube & Double Tube)
Types of Bits Used
* Tricon Bit 4” & 4-1/2” Dia
* Clay Bit 4-1/2” Dia
* Chopping Bit
* HX & NX Diamond Bit
* NXM Carbide Bit Bottom discharge
* NXM Carbide Bit Side discharge
INSITU TESTING
Standard Penetration Test (SPT)
The standard penetration test (SPT) is an in-situ dynamic penetration test designed to provide information on the geotechnical engineering properties of soil. The test procedure is described in the British Standard BS EN ISO 22476-3, ASTM D1586.
The test uses a thick-walled sample tube, with an outside diameter of 50 mm and an inside diameter of 35 mm, and a length of around 650 mm. This is driven into the ground at the bottom of a borehole by blows from a slide hammer with a weight of 63.5 kg (140 lb) falling through a distance of 760 mm (30 in).
During the drilling process SPT is conducted at regular intervals and ‘N’ counts are noted for every 6” penetration upto 18”. The sample is obtained with the help of ‘Split Spoon Sampler’.
The SPT ‘N’ counts are useful in providing an indication of relative density for cohesion less soils and consistency in cohesive soils. It is usually vital in correlating SPT results with the geotechnical parameters of soil.
Insitu CBR( Califoia Bearing Ratio)
The use of in-situ CBR apparatus on road construction contracts enables the bearing capacity of soils to be determined quickly and efficiently with minimum delay to contracting plant. BS 1377, BS 1924 and ASTM D4429 describe in-situ test procedures. We have conducted insitu CBR for many projects including QICT, Port Qasim and Integrated Container Terminal, Karachi Port.
Field Density Test
Field Density testing using Sand Replacement method is the industry standard in field density soil testing. This test is used to determine the field wet density, field moisture content and Field Dry Density of any given soil.
After Laboratory compaction of the same material has been tested, a comparison between the Field Dry Density and the Maximum Laboratory Dry Density is correlated and a ratio (%) can be issued as a report.
Apparatus used for FDT:
1) Sand pouring Cylinder Equipment/
2) Tools for leveling and excavating
3) Containers
4) Dry Clean Sand
5) Balance (Weight)
6) Speedy moisture
Plate Load Tests
We have highly trained geo-technical engineers and geologists to perform and supervise Plate Load Tests. Plate Load Test is used to determine the bearing capacity and settlement of soil and is mostly conducted where the structural loads are high. We have supervised and performed Pile Load tests on various sites including
Equipment and Apparatus
1.Counter weight such as box or platform with heavy material suck as concrete blocks and sand bags.
2. Hydraulic jack for applying the load.
3. Proving ring, 1 kg accuracy, for measuring the load.
4. Bearing Plate, 350mm 450mm and 600mm Diameter.
5. 4 Dial gauges, reference beams.
Pile Load Tests
Pile load tests are generally supervised by our engineers to either prove that piles are capable of sustaining the ultimate design load ("proof test") or to gain more detailed information that will enable a more efficient design ("load-deformation test"). For a proof test, a test pile is loaded to the ultimate design load (allowable design load times the factor of safety) and the deflection is measured at the pile head. If the deflection is within allowable levels, the test has "proved" that the pile is acceptable
The standard penetration test (SPT) is an in-situ dynamic penetration test designed to provide information on the geotechnical engineering properties of soil. The test procedure is described in the British Standard BS EN ISO 22476-3, ASTM D1586.
The test uses a thick-walled sample tube, with an outside diameter of 50 mm and an inside diameter of 35 mm, and a length of around 650 mm. This is driven into the ground at the bottom of a borehole by blows from a slide hammer with a weight of 63.5 kg (140 lb) falling through a distance of 760 mm (30 in).
During the drilling process SPT is conducted at regular intervals and ‘N’ counts are noted for every 6” penetration upto 18”. The sample is obtained with the help of ‘Split Spoon Sampler’.
The SPT ‘N’ counts are useful in providing an indication of relative density for cohesion less soils and consistency in cohesive soils. It is usually vital in correlating SPT results with the geotechnical parameters of soil.
Insitu CBR( Califoia Bearing Ratio)
The use of in-situ CBR apparatus on road construction contracts enables the bearing capacity of soils to be determined quickly and efficiently with minimum delay to contracting plant. BS 1377, BS 1924 and ASTM D4429 describe in-situ test procedures. We have conducted insitu CBR for many projects including QICT, Port Qasim and Integrated Container Terminal, Karachi Port.
Field Density Test
Field Density testing using Sand Replacement method is the industry standard in field density soil testing. This test is used to determine the field wet density, field moisture content and Field Dry Density of any given soil.
After Laboratory compaction of the same material has been tested, a comparison between the Field Dry Density and the Maximum Laboratory Dry Density is correlated and a ratio (%) can be issued as a report.
Apparatus used for FDT:
1) Sand pouring Cylinder Equipment/
2) Tools for leveling and excavating
3) Containers
4) Dry Clean Sand
5) Balance (Weight)
6) Speedy moisture
Plate Load Tests
We have highly trained geo-technical engineers and geologists to perform and supervise Plate Load Tests. Plate Load Test is used to determine the bearing capacity and settlement of soil and is mostly conducted where the structural loads are high. We have supervised and performed Pile Load tests on various sites including
Equipment and Apparatus
1.Counter weight such as box or platform with heavy material suck as concrete blocks and sand bags.
2. Hydraulic jack for applying the load.
3. Proving ring, 1 kg accuracy, for measuring the load.
4. Bearing Plate, 350mm 450mm and 600mm Diameter.
5. 4 Dial gauges, reference beams.
Pile Load Tests
Pile load tests are generally supervised by our engineers to either prove that piles are capable of sustaining the ultimate design load ("proof test") or to gain more detailed information that will enable a more efficient design ("load-deformation test"). For a proof test, a test pile is loaded to the ultimate design load (allowable design load times the factor of safety) and the deflection is measured at the pile head. If the deflection is within allowable levels, the test has "proved" that the pile is acceptable