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Soil Mechanics Facilities

Students of both Civil and Structural Engineering attend the Soil Mechanics Laboratory as part of their course work.  The students obtain vital hands on experience and practical knowledge in conducting Soil Mechanic tests.

Students obtain an insight into soil properties measurement techniques and the typical values for many soils. This knowledge will prove invaluable in their future careers in Civil and Structural Engineering.

Soil Strength (Triaxial)

The measurement of total stress or effective stress requires the use of different procedures and therefore different accessories and equipment.

Total stresses are normally measured in a triaxial cell where the sample is subjected to an all round confining pressure. A load is then applied through a piston onto a pressure pad. The sample is then confined in a rubber membrane and no drainage in to or out of the specimen is allowed. Pore water pressures are not normally measured and the quick undrained test is often referred to as the QU-TXL test. An extension of the QU test is the unconsolidated undrained test (UU), this is similar to the QU test but is run at a slower rate in order to measure pore water pressure.

Effective stresses when measured in a triaxial cell are more complex in their nature. Numerous parameters may be measured including back pressure, pore water pressure and volume change. From these values various engineering properties can be calculated.

Effective stress tests are usually referred to as consolidated drained (CD) or consolidated undrained (CU). Generally the CD test is applicable to sands, and either the CU or CD test is applicable to clays. There are many special test variations within these basic test groupings.

Direct Shear Testing

Every building or structure which is founded in or on the earth imposes loads on the soil that supports the foundations. The stresses set up in the soil cause deformation of the soil. Stress failure is caused by slippage of soil particles, which may lead to sliding of one body of soil relative to the surrounding mass.

The  Direct and Residual Shear Apparatus has:

  • Micro processor control
  • Large on-board LCD screen display
  • Direct entry via touch sensitive keyboard
  • Rapid approach and return to start datum
  • Fully variable speed, 0.00001 to 9.99999 mm/minute
  • Accepts specimens up to 100 mm square

Pilcon Hand Vane Tester

The Pilcon Hand Vane Tester is an accurate and portable instrument for the determination of in-situ shear strength of cohesive soils, either or on site undisturbed samples in the laboratory.

The instrument comprises a torque head with a direct reading scale which is turned by hand. A non return pointer indicates the reading.

 

 

Autonomous Data Acquisition Unit (ADU)

The Autonomous Data Acquisition Unit (ADU) is a sophisticated data acquisition unit that provides the link between your computer and the transducers connected to your test equipment featuring:

  • Up to 32 input/output channels
  • Up to 100 readings per second in normal multi-tasking mode
  • Standard RS232C interface
  • Compatible with a range of transducers for almost any test requirements

With on-board intelligence and memory, the ADU takes control of the data acquisition process. The user is not required to do any programming. With all real time activities being controlled by the ADU, the computer may be switched off or used for other purposes.

DataSystem Transducers

DataSystem Transducers link geotechnical soils testing devices to the Autonomous Data Acquisition Unit (ADU).

A comprehensive range is available which includes:

  • S-type Load Cells
  • Submersible Load Transducers
  • Displacement Transducers
  • Volume Change Transducers
  • Pressure Transducers

DataSystem 7 Software

DataSystem 7 (DS7) software is a comprehensive soil testing package designed to operate on a standard PC with ADU data logger and range of transducers.

The principal functions of the software are:

  • Input of sample information; this can be done manually or imported from an AGS format data file
  • Step-by-step instructions for starting tests and test stages with built-in functions to aid set-up calculations where appropriate
  1. All procedures follow the selected International Standard (ASTM or BS).
  2. Acquisition and real-time display of transducer data; multiple tests can be monitored concurrently.
  3. Analysis of test data to produce the results required by the selected International Standard.
  4. Generation of reports as required by the selected Standard in a format which can be modified by the test house using a standard word processor.
  5. Generation of AGS-formatted report files for fast electronic transfer of results to the testing house's customers and for integrating into the test house's laboratory management systems.

The following programs for testing to British and ASTM Standards are available:

  1. Undrained Triaxial Shear Strength
  2. CU/CD Triaxial Shear Strength
  3. One Dimensional Consolidation
  4. Direct and Residual Shear Strength
  5. California Bearing Ratio