Soil penetration test pdf

In addition, the rolling resistance model was used to account for the high inter-particle friction angle resulted from particle angularity. A series of DEM biaxial tests were performed to investigate the mechanical properties of lunar soil. The obtained results from the DEM biaxial tests indicate that the mechanical behaviour of lunar soil is different from that of terrestrial soil due to the inter-particle cohesive forces and low gravity on the Moon.

In tests, the grains near the penetrometer have experienced intense loading and unloading with complex displacement paths. In the meantime, the granular velocity, stress and strain fields were also changed during the penetration process.

This study reveals that the lunar soil has relatively small friction and strength when compared with the terrestrial soil. This is a preview of subscription content, access via your institution.

Rent this article via DeepDyve. Cambridge University Press, Cambridge. Robertson, P. Can Geotech J 23 4 , — Article Google Scholar. Been, K. Sladen, J. Houlsby, G. Proceedings of the Apollo 11 Lunar Science Conference. Houston — Proceedings of the Lunar Science Conference. Matsushima, T. J Aerosp Eng 22 1 , 15—23 Alshibli, K. J Geotech Geoenviron Eng 5 , — Garboczi, E. Powder Technol 1—3 , 96— Oravec, H. J Terrramech 47 6 , — Jiang, M. Adv Space Res 52 1 , — Chin J Geotech Eng 33 2 , — Exceptions can occur when rod energy is low or the bottom of the casing is below the test section.

When the intention is to measure N values, standard 35 mm i. SPT equipment used abroad should be carefully evaluated, because the energy delivered by the hammer may be quite variable and, on average, different to that given by UK automatic trip hammers.

But such factors cannot always be ignored, and may be considered important under particular circumstances. This Section has shown that, under certain circumstances, the test may be greatly affected by factors other than the ground. Ground resistance is provided by friction on the outside and inside of the spoon, and by end-bearing.

Thus the N value results from a test on a relatively small volume of ground, that is performed dynamically and intermittently, to failure, and beyond, in conditions which may be either undrained or partially drained. When joints are widely spaced and tight, such as in less-weathered weak rocks, the resistance of the rock mass to penetration is a function of porosity and intact strength.

A high porosity allows the fractured rock to be pushed aside; a low A slight change in water strength makes it easier for the split spoon content can greatly change the to fracture the rock Meigh, ; Leach SPT N value in intact chalk and Thompson, The N value will reflect these factors.

Simple correlations, which do not consider more than one factor, are likely to be unreliable. The system recommended here uses N values corrected for both energy and overburden pressure. Whatever system is adopted, its basis must be clearly stated. The measured value of undrained shear strength obtained from other in-situ or laboratory tests depends upon test size and method, thus affecting correlations with the SPT.

Therefore, in order to enhance its reliability, site specific correlation with directly determined parameters should be carried out whenever possible. At its simplest, it is a low- quality sampler. At its most useful it is a rapid, inexpensive, qualitative test which can provide data even when other techniques of sampling or testing are not viable or cannot be justified financially.

I ncreasing use of the test then led to attempts to correlate its results with other geotechnical characteristics. This tool is used to drive the sampler into the borehole. The mass of it is It is used to stop the hammer on a certain point.

Before conducting the test, we have to decide the total depth of penetration bore and depth interval to carry the test and collect the sample the same.

Generally, depth of bore is up to groundwater table or up to hard strata below ground surface. We can decide the intermediate test depth of every 1m. So, SPT is conducted at every one meter of boring below ground level and soil samples are collected at the same depth. Once the boring of the hole is done up to desired depth 1 m depth we decided remove the drilling tools from the borehole and clean all the disturbing materials.

After that fit the soil sampler named as split spoon sampler with the drilling rod and lower it into the borehole. Now, the rest split spoon sampler attracted with drilling rod at bottom of the drilled borehole of undistributed soil. Keep ready test equipment the Hammer, Anvil, and guiding rod and assemble them with each other properly. Mark the distance of mm on the drilling rod to observe penetration details. Firstly drive the drop hammer on the bottom of a borehole by blows from the slide hammer with a mass of Now, Count the number of blows required to reach or drive depth of mm 6 in.

Similarly , again drive sampler in soil and count the blows needed to penetrate the second and third mm 6 in. In this test, the total sum of the number of blows required to drive the sampler mm 6 in. If a number of blows are required to drive the sampler to a depth of mm excess of the value 50 , it is considered as a refusal and the test is discontinued.

The entire sampler may sometimes sink under its own weight when a very soft sub-soil stratum is encountered. The Test shall be made at every change in the stratum or at intervals of not more than 1. The first 6 inches is considered as seating drive. The number of blows required for the second and third 15 cm 6 inches of drive added is recorded as the penetration resistance value N of the soil.

If the test is to be carried out in gravely soils , then the driving shoe is replaced by solid degree cone. Below the water table, care should be taken to avoid entry of water through the bottom of the bore due to loosening of soil happens. Water should be added as necessary to maintain the water table level in the bore hole. Stop dropping weight, when the sample penetrates less than 25 mm under 50 blows. Stay up the good work!