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Geotechical Lab

Triaxial Testing Equipment:

The specimen is vertically enclosed with a thin rubber membrane and placed between two rigid ends inside a pressure chamber. The upper plate can move vertically and apply vertical stresses to the specimen. The axial strain/stress of the sample is controlled through the movement of this vertical axis. Also, the confining pressure is controlled by the water pressure surrounding the sample in the pressure chamber. The volume change of the sample is also controlled by measuring the exact volume of moving water.

Depending on the combination of loading and drainage condition, three main types of triaxial tests can be carried out:

  • Consolidated – Drained (CD)
  • Consolidated – Undrained (CU)
  • Unconsolidated - Undrained (UU)

 

triax-frametriax-cell-sampletriax-sample

 

Seepage Tank:

The seepage tank experimental set-up is designed for the investigation of flows in subsoil. In a sediment filled tank with a viewing window made of special glass, flow lines can be made visible using a contrast producing medium (ink). The height adjustable overflow pipes provide the necessary head. Measuring connections are fitted to the base of the tank, these can be connected to multiple tube manometers. Various fittings enable comprehensive investigations on flows under pile planking, the pressure distribution on containing walls, and ground water flows around impermeable bodies to be performed. The closed water circuit with supply tank and pump enables the seepage tank to be operated independent of a mains water connection.

seepage tankflow lines

 

Ground Penetrating Radar:

In its most basic sense, ground-penetrating radar (GPR) is a geophysical technique that collects and records information about the subsurface. It is a technique that has been employed in such fields as engineering, geology, environmental studies, and more recently, archaeology. Currently, there are three antennas (100 MHz, 250 MHz, and 500 MHz) available at our geotechnical lab for subsurface exploration.

gpr 250gpr 100gpr survey

 

Seismic Refraction Testing Equipment:

Seismic Refraction surveys are used for excavation purposes to map the bedrock depth and evaluation rock rippability. Seismic refraction measurements are applicable in mapping subsurface conditions for various uses including geologic, geotechnical, hydrologic, environmental, mineral exploration, petroleum exploration, and archaeological investigations. Seismic Refraction investigations are commonly used to determine layer thickness and/or the subsurface compressional wave velocity of the overburden and underlying bedrock or to water table, stratigraphy, lithology, structure, and fractures. This inherently shallow technique requires that compressional seismic wave velocities increase with depth so wave refraction occurs. Our equipment is capable of handling 13 geophone channels, including triggering channel.  

 

 SRS-Olson  SRS-FieldSRS-Hammer 

 

Relative Density:

The purpose of this lab is to determine the Maximum-Index Dry  Density/Unit Weight of cohesionless, free draining soils using a vertically vibrating table. Our lab has both 0.1 cu-ft and 0.5 cu-ft Relative Density Mold sets.

ELE_Relative_Density_Set/rel-den-samplerel-den-cell    

Consolidation:

Our LoadTrac-II system fully automates the performance of a Controlled Strain Loading Consolidation (CSL) test. Once a soil sample is in place, and the test conditions selected, the LoadTrac-II system will run the entire test from start to finish. The LoadTrac II system consolidates the sample through a loading path specified by the user using constant rate of strain loading. 

consolodation-sampleconsolidation-pc 

 

Unconfined Compression:

Unconfined Compression Test is a quick test to obtain the shear strength parameters of fine grained soils either in undisturbed or remolded state The test is strain controlled and the soil sample is loaded rapidly.

uc-testinguc-sampleuc-failedsample   

 

Pneumatic Shear Apparatus

pnumatic-shearThe Humboldt HM-2560A Direct/Residual Shear Apparatus utilizes the pneumatic loading concept for applying the vertical load to the sample. In doing so, this self-contained model eliminates the need for cumbersome loading weights used in dead weight-type systems. Complies with ASTM D3080, AASHTO T236 and BS1377 standards. Features include:

  • Four channels with real-time data acquisition
  • Backlit LCD display
  • RS232 interface for computer or printer.
  • Nonvolatile test data storage and instrument calibration
  • Battery-backed real-time clock
  • Auto conversation of instrument calibration between English or Imperial units and SI or metric units
  • Test setup and selection via keypad
  • Automatic triggering of test logging data
  • View logged test data via the LCD display
  • Logging rate as fast as 0.1 second/reading
  • Humboldt HMTS, Basic, User-Defined Level software included for data acquisition

 

Power Mechanical Earth Drill

earth-drillFor soil sampling, construction and more, earth augers are gasoline powered and portable. Using one operator, they allow fast and easy drilling. They feature snap-on or screw-on augers and extensions. Engine mounted on wheel-base carrier keeps motor noise and fumes away from the operator. Torque tube eliminates counter torque. Features such as the carrier and torque tube offer greater mobility, beneficial in areas inaccessible to large equipment, on slopes and horizontal drilling, various standard sampling methods to obtain material samples.

 

 

 

 

 

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