Advanced Geotechnical Instruments

To design foundations, embankments and other soil structures, Geotechnical Engineers require methods of assessing the engineering properties of soils. Some of the more complex phenomena that occur in the soils have often been difficult to recreate in the laboratory: seismic activity, vibration, unsaturated condition, control of principal stresses etc are areas which have proven difficult to replicate, despite their importance being understood. This was partly due to lack of test systems capable of being reproducing these effects and complexity of test systems that were developed to carry out such work.

Today Ultra Technologies through its overseas associates M/s Wyekham Farrance Ltd., UK offer a number of advanced computer/software controlled test systems which allow the geotechnical engineer to perform the most complex test regimes via a user friendly software interface. Some of these systems include

• 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 system 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 test system helps in the study of effects of construction by simulating past loading regimes as a consequence of historic accumulation of debris and sediments and future loading based on a range of construction scenario. The phenomenon and problems associated with liquefaction concern saturated cohesion less soils and the effect can be simulated in the laboratory through cyclic triaxial testing. Similarly the cyclic loading due to wave effect, pile driving, blasting, rail track etc can be simulated through Cyclic/Stress Path Triaxial System.
  
  




• Cyclic simple shear apparatus is generally used for research into the dynamic field of soil behaviour, since it can simulate quite easily many different field loading conditions such as stability under seismic events of submerged slopes of continental shelf, degradation of shear stress for saturated granular soil, evaluation of liquefaction parameters etc.
  
  
• Dynamic Hollow Cylinder Apparatus is the only triaxial system that can control the magnitude and direction of principal stresses. This apparatus allows the investigation of the rotation of principal stresses within the soil sample, which is done through independent controlling of the direction and magnitude of the principal stresses.