Assignmetn

What OSHA, examination, emphasize is to conduct a manual analysis of soil samples to provide a prowler classification of the soil. There are a variety of tests which can be used to analyze soil and determine its qualitative and quantitative properties. One of the methods that are used in the analysis and classification of soil is thumb penetration test and pocket penetrometer. For our experiment, we applied the two test. The analysis below uses the two types of test to classify soil.

Thumb Penetration Test

This test used to evaluate the unconfined compressive of cohesive soils. The thumb penetration test involves making a ball from the soil and then pressing the thumb finger through the soil, the depth in which the finger goes determined the type of soil. Based on the length of the thumbnail we determine the type of soil as type A, B and C. Type A soil the thumb penetration is shallow, while type B soil the finger goes further than A and type C the finger goes further than A and B. Therefore using this type of classification one can determine the soil and classify the soil into A, B and C.

For the accomplishment of our practical, we decided to take some soil for analysis from one our friend’s residence. In our experiment, after we dug and passed the grass layer, we grabbed some of the soil from the end of the hole we made in the backyard of one of our friend’s house. The soil we obtained we made it a ball like and applied the thumb penetration test. We noticed that the soil needed great effort to be penetrated by thumb as we pressed the thumb into the soil and did not go further which mean that the type of soil is A ( see figure # ). Secondly, we applied the Pocket Penetrometer to examine our sample soil further.

Pocket Penetrometer

The Pocket Penetrometer is designed as a handy device can be used to conduct a visual classification soils by the field worker. As the result of the reading, we can verify where excavation sidewalls require shoring or not based on OSHA cohesive solids classifications. The device gives a compressive strength of the soils, therefore, more effective than thumb penetration.

We used in this test spring operated instruments to determine the unconfined compressive strength of the soil. The reading displays when the pushed the instrument into the soil via indicator sleeve. The penetrometer is calibrated in either ton per square foot or kilograms per square centimeter. However, the error rate for this experiment is between +-20 to 40%.

In our soil test by using the pocket penetrometer, we collect some of the soil from the bottom of the hole we made to make sure that we passed the grass’s layer. We put the soil sample in a paper cup (see figure #). The white ring on the penetrometer is designed to get the test reading on the scale. After we gripped the handle and pushed the tip of the penetrometer into the sample soil, the pothole-marked on the soil “tip.” The reading taken from the lower side of the white ring is 2.0 TSF. That’s mean the soil types A.

reference

https://www.osha.gov/dts/osta/otm/otm_v/otm_v_2.html