1. Determine the CBR value of a local dune sand to be used as a subgrade layer using the test results summarized in the table below. Apply any necessary corrections.

| Penetration (in.) | 0.00 | 0.08 | 0.10 | 0.12 | 0.14 | 0.16 | 0.18 | 0.20 | 0.22 | 0.24 | 0.26 | 0.28 | 0.30 |
|-------------------|------|------|------|------|------|------|------|------|------|------|------|------|------|
| Load at Top (lbs) | 0.0 | 8.5 | 20.5 | 48.0 | 63.8 | 87.8 | 97.8 | 105.8| 103.2| 107.0| 112.4| 116.7| 120.0|
| Load at Bottom (lbs) | 10.1 | 10.2 | 15.2 | 20.5 | 16.7 | 18.3 | 23.8 | 30.0 | 90.8 | 108.1| 144.4| 149.2| 152.9|

Note: Please check the values in the table for accuracy, as they appear to be inconsistent or incorrect. Adjust them if necessary before performing any calculations.

The California Bearing Ratio (CBR) test is used to determine the strength of subgrade soils, such as the local dune sand in this case, for road construction. The CBR value of the local dune sand can be calculated using the provided test results by dividing the load at the bottom by the load at the top and multiplying by 100.

Explanation:

The California Bearing Ratio (CBR) test is used to determine the strength of subgrade soils, such as the local dune sand in this case, for road construction. The test involves applying loads to a soil sample and measuring the penetration resistance. The CBR value is calculated as the ratio of the load required to penetrate the soil sample to the load required to penetrate a standard material.

In this question, the given information includes the penetration values and the loads at the top and bottom of the local dune sand sample. To determine the CBR value, corrections may be necessary to account for factors such as the size and shape of the sample, moisture content, and compaction conditions.

Using the provided test results, the CBR value can be calculated by dividing the load at the bottom by the load at the top and multiplying by 100. The CBR value indicates the relative strength of the local dune sand as a subgrade layer. Higher CBR values indicate stronger and more suitable soils for road construction.

Learn more about cbr value determination for local dune sand as a subgrade layer here:

https://brainly.com/question/33196364

#SPJ14