Advance Geotechnical Equipment

SHEAR STRENGTH OF SOIL

Shear Testing Machines

This test covers the determination of the consolidated drained shear strength of a soil material in direct shear. Shearmatic, digital automatic direct/residual shear machine with programmable pneumatic loading is an advanced microprocessor model, driven by a high-resolution stepper motor. It incorporates a pneumatic closed loop control system for the automatic application of a normal load by a high performance pressure regulator, therefore eliminating the need for manual application of dead weights. This system can perform different types of automatic shear tests since it is possible to control the different parameters measured during the test.

Large Digital Shear Box

The new digitally controlled large shear box is ideal for testing geosynthetics and also soils and other materials that contain large particles of upto 120 mm largest dimension. Sample sizes upto 300 mm square can also be tested, with various inserts allowing the testing of a smaller sample size. By using the larger sample size it is possible to gain a more representative indication of shear strength. A large shear box can be used to obtain the angle of friction between many materials.

Torsional Shear

The residual shear strength of soils is sometimes also termed as the ultimate shear strength. This is the strength of soil when it is sheared to large displacements, for example along the failure plane of landslide or in a fault zone. The remoulded specimen is used to determine the residual shear properties of soil.

ADVANCED SOIL TESTING

Stress Path Systems

To replicate the changes in stress experiences insitu during excavations, constructions that occur due to natural events. Soils in general are non elastic materials and their behaviour in-situ depends on factors including magnitude and direction of stress changes, previous history of loading etc. It is therefore desirable to be able to trace the stress history of an element of soil.. The use of stress path test in the laboratory enables field changes past, present and future to be modelled.

Cyclic/Stress Path Triaxial Systems

This equipment is used to reproduce in the laboratory any vibration, shock and cyclic forces applied to the soil samples, to give engineers a better understanding of how soil behaves in these unique situations. This finds applications in construction to simulate the past loading regimes, liquefaction studies, wave effect on offshore structures, laboratory pile tests, blasting and effect of vibrations due to movement of trains.

Unsaturated Triaxial Testing

To investigate the behavior of soil in unsaturated state with the measurement of suction. Testing of soil in an unsaturated state with measurement of suction is vital to understand soil behavior properly. This technique finds application in study of rainfall induced slides, swelling soils and collapsing soils.

Resonant Column & Torsional Shear System

This is a new Resonant Column and Torsional Shear device incorporating a special loading system with more than 5 Nm torque range and a laser based angle measurement unit is suitable for testing saturated soils. The system operates with cell pressure up to 1.5 Mpa.. The acquired data are presented, printed and saved in a file while it’s easy to switch from RC to TS tests. The system comes as a complete, self-contained unit with all of the equipment required to perform tests.

Dynamic Hollow Cylinder Apparatus

A unique triaxial system which can control the magnitude and direction of principal stresses. The standard triaxial testing system allows to set up and control the magnitude and frequency of the applied stresses, but not the direction. This system can control the magnitude and direction of the principal stresses:

vertical and horizontal stress I cyclic mode
inner and outer cell pressure in cyclic mode
Back pressure in static mode.

ROCK TESTING

Rock mechanics is a theoretical and applied science concerning the physical behaviour of rocks subjected to stress conditions of different origin. In general terms, rock mechanics involves the study of underground works such as tunnels, and surface construction such as open quarries or dam foundations. When a rock sample is subjected to defined stress conditions in the laboratory, the stress-strain diagram can show behaviours of non linearity also for very small strains, hysteresis, anisotropy, fluage conditions, etc. All these phenomena can be mathematically described.

Automatic Test Systems

Controls rock mechanics ADVANTEST 9 Automatic Test Systems are designed to test various materials from soft sandstone to high strength basaltic samples. According to the reference standards, during the test the compression load on the rock specimen shall be applied continuously without shock, in such a manner to produce a strain rate as constant as possible, so that failure will occur within 5-10 min of loading or alternatively at a constant rate of stress, within the limits of 0.5-1.0 MPa/sec. Moreover, for triaxial tests, the confining pressure has to be maintained constant to within ± 1%. this System has been designed to completely fulfill these strict specifications of the test procedures. Determination of Elastic Modulus and strength characteristics of rock specimens in uniaxial and triaxial conditions. Tests performed under control of Load/Stress; Displacement & Strain