Standard Penetration Test Equipment SPT Travel Hammer 2" 63.5kg
Standard Penetration Test Equipment SPT Travel Hammer 2" 63.5kg for Soil Sampling
Spt Equipment, Soil Sampler, Standard Penetration Test
SPT split tube sampler Components including ball valve adaptor, split tubes, basket retainer and SPT shoe.
SPT Split Tube Sampler is designed for carrying out the Standard Penetration Test (SPT) to BS 1377: Part 9: 1990 and ASTM standards. The Top Ball Valve Adaptor, pair of Split Spoons, and open SPT Shoe compose a complete set of Split Tube Sampler. A Basket Retainer made from steel or plastic also is available as an option with the sampler. The ball valve adaptor prevents samples from being washed out of the sampler when it is withdrawn from the borehole. A 60 degree nose cone or long solid rod with 60 degree point is available for carrying out SPT (c) tests in gravel and loose material. The screw connection on the top adaptor depends on the type of drill rods being used to drive the sampler. Most frequently used rods are 1-1/2" B.S. Whitworth, NWY Rod, BW or AW.
The standard Split Tube Sampler is 2" (50.8 mm) OD x 1-3/8" (34.9 mm ) ID x 18" (457 mm) / 24" (610 mm) long. For heavy driving conditions, the Heavy-duty "Tuflok" design is available.
The Standard Penetration Test (SPT) is a widely used soil exploration method for obtaining a relative indicator of cohesive soil strength or density of granular soil. SPT sampling in cohesive soils involves driving a split barrel (spoon) sampler on the bottom of a drill string to recover a disturbed sample whilst in granular soil a solid cone replaces the split spoon. The sampler is driven into the soil by a standard 63.5kg hammer/drop weight falling a distance of 760mm. It is advanced in six 75mm increments and the sum of the blows required to penetrate the last four increments are used to calculate the 'N value'.
It has been demonstrated that the type and operational characteristics of the SPT hammer can have a significant influence on the resulting SPT 'N values'. BS EN ISO 22476-3 requires the energy ratio (Er) (energy imparted by the SPT hammer to the rods compared to the theoretical energy of the hammer) to be recorded and a certificate of calibration provided.
The Energy Ratio (Er)
The influence of different types of equipment on measured SPT N values is well known. The main reasons, as noted in BS EN ISO 22476-3, are that energy losses occur due to friction of the hammer compared to free fall, and during impact between the hammer and the anvil. Clayton (1995) reported energy ratios of between 43% and 85% for tests from eight different countries with a measured value for a UK automatic trip hammer of 73%. BS EN ISO 22476-3 states that the energy ratio of the equipment used has to be known "if the N values are to be used for quantitative evaluation of foundations or comparisons of results".
The British Standards provide a recommended method for measuring the actual energy, calculating the energy ratio and also provides a specification. Measurements are required on an annual basis unless the equipment has been modified, damaged or as requested by the client. Designers may specify more frequent calibrations and, in addition, calibrations at the commencement of large contracts where multiple rigs and SPT equipment are to be utilised would be recommended.
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