Effect of Loading Duration on the Parameters Obtained from Consolidation Test
Engineering and Technology Journal,
2013, Volume 31, Issue 19, Pages 59-69
AbstractConsolidation properties of clay soils are evaluated in the laboratory using the one-dimensional consolidation test. The one-dimensional consolidation testing procedure was first suggested by Terzaghi (1925). In this procedure, the load on the specimen is applied and usually kept for 24 hours. After that, the load is doubled. Therefore, the duration of this test may continue at least 1 week and this duration is unpreferable for traditional purposes if the work is huge.
In this paper, decreasing of applied loading test time has been studied through a new proposed time for applied loading. The results of a new time procedure have been compared with standard (conventional) Oedometer tests that they have been carried out on remolded samples of clay to investigate the difference percentage if quick tests are adopted instead of long tests.
The comparison shows that the compression index increases with the increase test time, therefore, the compression index must be modified (use 1.1 Cc) when employed to calculate the settlement of soil. Also, the elapsed time of test is significant to the determination of swelling index. So, the test time of applied load should be not less than 2hrs.
The results show that two hours are enough to reach 90 % consolidation (t90). The values of pre-consolidation pressure predicted depending on the results of quick test are always smaller than those predicted depending on the results of conventional test results. Finally, two hours LID is enough for calculating the coefficient of permeability depending on the parameters obtained from consolidation test.
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