Geotechnical investigation is subsurface testing of the soil or rock formations carried out by conducting on-site explorations, sampling, boring, logging and laboratory testing. Geotechnical studies help getting detailed data on the geological conditions of the site which gives a geotechnical engineer sufficient data to recommend foundation design. The collected data is analyzed and geotechnical criteria for foundations, retaining walls, site drainage, etc. are developed.
These geotechnical investigations have many uses, such as; designing the foundation for buildings or other related structures, roads and bridges, dams and hydropower. It also plays a vital part in establishing retaining structures, constructing underground structures such as tunnels and quarries which are subjected to soil pressure from all sides, constructing earth dams that require proper knowledge of engineering properties of soils and rocks. All in all, these investigations play a crucial role in researching the impact of development on various construction projects.
AKM Geotechnical provides a comprehensive range of geotechnical investigation services and believes that an efficient and effective geotechnical study is an integral component of any proposed civil engineering project. We ensure that the ground investigation is designed and implemented correctly to meet the project requirements. Where necessary, our multi-disciplined teams are able to integrate the scope of works to cover both geotechnical and environmental concerns in order to provide a technically robust and cost-effective site investigation solution.
WHY ARE GEOTECHNICAL INVESTIGATIONS SO IMPORTANT?
The primary reason for geotechnical investigations is to find possible anomalous subsurface conditions before beginning a project. The costs of not performing a geotechnical investigation can be astronomical. AKMG provides geotechnical investigation services and construction materials monitoring services throughout all phases of feasibility/planning, design development, construction and post-construction.
Our team of professionals has the expertise to perform the following field related tasks
Geotechnical drilling is a method by which core samples of rocks and soil samples are recovered and then tested both in-situ and ex-situ to determine engineering properties of these samples and cores. This is a very integral part of any project as unstable and unsafe rocks and soil could undermine the integrity of the site. Accurate drilling establishes a safe foundation for whatever project the contractors are going to work on.
Collection of disturbed and undisturbed samples (DS & UDS)
During drilling when we acquire the samples from the ground, we usually have two types of samples; disturbed and undisturbed samples.
- DISTURBED SAMPLES (DS)
When the structure, texture, density, natural water contents or the stress conditions of the samples cannot be taken as in ”in-situ conditions”, we refer to it as disturbed samples. However, these samples can be recovered.
- UNDISTURBED SAMPLES (UDS)
Without disturbing the structure, texture, density, natural water contents or the stress conditions of the sample is called an undisturbed sample. These are normally taken in sample barrels such as Shelby, Denison and pitcher samples which retains the original in-situ condition of soil samples when taken for tests in laboratory.
Performing standard penetration test (SPT)
The Standard Penetration test (SPT) is common in situ testing method used to determine the blow count commonly referred to as “N Values” of subsurface soils. The standard penetration tests are carried out in borehole according to the ASTM standard (ASTM D1586).
Borehole logging/Field logging
Borehole logging is a time and money-saving approach to gaining detailed information which is otherwise only obtainable from performing and analyzing numerous cores. Borehole logging data is typically used to characterize geology, fracture patterns, fluid flow, and geologic structural properties. Standard guide ASTM D5434 for field logging of sub-surface exploration of rock and soil are followed.
Test pit excavation and logging
Test pits are used for sampling and closely examining the engineering properties of soils. The plan view of the pit is usually circular or rectangular. Test pits can be excavated through machinery or hand tools.
The Lugeon test, sometimes call also Packer test, is an in-situ testing method widely used to estimate the average hydraulic conductivity of rock mass. It is indeed In situ test of formation permeability performed by measuring the volume of water taken in a section of test hole when the interval is pressurized at a given pressure (10 bars -150 psi). It is used primarily in variably permeable formations under the evaluation of fracturating.
The test is named after Maurice Lugeon (1933), a Swiss geologist who first formulated the test. Basically, the Lugeon test is a constant head permeability type test carried out in an isolated part of a borehole. The results provide information about hydraulic conductivity of the rock mass including the rock matrix and the discontinuities.
This test measures the seepage of water through the soil. There are several methods to perform permeability tests such as falling head, constant head and laboratory methods that are carried out in soils. The falling head method of determining permeability is used for soil with low discharge, whereas the constant head permeability test is used for coarse-grained soils with a reasonable discharge in a given time. For very fine-grained soil, the capillarity permeability test is recommended. The knowledge of this property is much useful in solving problems involving yield of water-bearing strata, seepage through earthen dams, the stability of earthen dams, and embankments of canal bank affected by seepage, settlement, etc.
Field Density Test (FDT)
Field Density Test is a Quality Control test carried out at site for knowing the increased density or compaction achieved at site on the soil layer.
Grout is a mixture of cement, sand and water which is used to fill the gaps in any structure such as concrete, tiles, water proofing etc.
Geological mapping and survey
Geologic mapping involves plotting the location and attitude of the various rock units, faults and folds on a base map. Geologic maps are used to investigate geologic hazards, mineral resources, groundwater aquifers, and just plain science.
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