consol-pt1 - University of Missouri Columbia Consolidation...

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University of Missouri – Columbia Department of Civil and Environmental Engineering Consolidation Test Part 1 p.1 CONSOLIDATION TEST PURPOSE The purpose of this experiment is to teach you how to perform a one-dimensional consolidation test on a specimen of compressible, cohesive soil. Consolidation tests are one of the most important types of tests performed for geotechnical engineering purposes. For small testing laboratories, consolidation testing may represent the most sophisticated level of testing conducted. Larger laboratories may employ high-technology electronic equipment in consolidation testing to speed up the test and to provide more detailed information than can be obtained with conventional apparatus. Regardless of the complexity of the equipment, geotechnical engineers routinely make direct use of the results from consolidation tests to make major decisions concerning the type and size of foundations to use for projects of all kinds. EQUIPMENT Consolidation Cells The term "consolidation cell" refers to the assembly of a confining ring, loading cap, reservoir, and suitable appurtenances (Fig. 1). The soil is trimmed into the ring and is loaded through a cap and porous stone, which move down inside the ring during compression of the soil. Fixed rings (Fig. 1a) and floating rings (Fig. 1b) have been used. Undesirable friction that develops between soil and ring is less with a floating ring, but the floating rings are less convenient to use and friction can usually be reduced to tolerable levels by other means. The porous stones are several orders of magnitude more permeable than typical samples of fine-grained soil. To prevent the soil from clogging the pores of the stone, a sheet of filter paper is usually placed between the stone and soil sample. The reservoir is filled with water to ensure that the soil remains essentially saturated. The ratio of diameter to thickness of the soil sample is usually between 3 and 4. Diameters vary widely but are typically 2 to 3 inches. This sample size is mainly set by economical considerations in that undisturbed samples with diameters of the order of three inches are obtainable with standard boring and sampling equipment, and the loading equipment in use in soils laboratories is capable of delivering adequately high pressures on samples of this size. When compacted or hand carved samples from test pits are tested, sample diameters up to about 4.25 inches have often been used. In cases where the soil is fissured or finely stratified, it may be necessary to use sample sizes large enough so that a reasonable number of these inhomogeneities are included in each specimen. Although samples larger than about 4.5 inches are rarely used in the U.S., samples up to 20 inches in diameter have been used in Great Britain. Because the rate of settlement is proportional to the square of the drainage distance, it is
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This note was uploaded on 09/23/2011 for the course CIVIL ENGI CE 3400 taught by Professor Rosenblad during the Spring '11 term at Missouri (Mizzou).

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consol-pt1 - University of Missouri Columbia Consolidation...

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