A numerical method based on least squares nonlinear regression for the evaluation of the consolidation parameters of soils from consolidation tests is presented. Consolidation test video lecture of consolidation of soil chapter from soil mechanics subject for civil engineering students. The consolidation test procedures have been developed from those in lambes book. Deformation of soil grains elastic degree water saturation pdf file. The results of consolidation test are very much helpful in. When a compressive load is applied to soil mass, a decrease in its volume takes place, the decrease in volume of soil mass under stress is known as compression and the property of soil mass pertaining to its tendency to decrease in volume. Pdf consolidation of soils testing and evaluation researchgate.
Secondary consolidation usually estimated from a lab consolidation test. Tests are performed on specimens prepared from undisturbed samples or compacted disturbed samples undisturbed samples should be trimmed directly in. One test on every other gradation test sample of zone a and zone b fill item 41, and for each compaction test item 1 i. The test is known as a one dimensional consolidation test also known as an oedometer test. The consolidation attributes of soils of low permeability can be determined with the onedimensional consolidation test. The consolidation as compression of soil usually occurs in three stages. Consolidation is the process in which reduction in volume takes place by expulsion of water under longterm static loads. Consolidation test on soil by consolidometer or oedometer. This chapter provides information on common laboratory test methods for soils and rocks including testing equipment, general procedures related to each test, and parameters measured by the tests. Estimating foundation settlement by onedimensional consolidation tests by harold j.
Consolidation the reduction of bulk soil volume under loading due to flow of pore water. D243511 standard test methods for onedimensional consolidation. The secondary consolidation portion of the consolidation curve is approximately linear on an elog time plot. When a compressive load is applied to soil mass, a decrease in its volume takes place, the decrease in volume of soil mass. It is pretty intuitive that the stress applied to the soil weight of the footing and the load the foot distributes depends on the rates and distance of settlement. The theory of consolidation is of major interest in the analysis of deformations of por ous media, in soil and r ock mechanics, in nonsteady gr oundwater movement, and in the subsidence due to gr. Permeability in directly an indication of the ability of a soil to allow fluids to flow through it. Since the settlement analysis of the foundation depends mainly on the values determined by the test, this. Consolation is process in which the volume of the soil decrease due to expulsion of water from the pores. Compaction is intentionally done to produce a high unit weight of. Test to be made adjacent to inplace soil density test item 2 and each atterberg limit test item 5 for correlation. Lambe and the measurement of soil properties in the triaxial test by a. When stress is applied to a soil that causes the soil particles to pack together more tightly.
The consolidation parameters obtained by this test are used to determine the. The problem will be illustrated for the situation shown in fig. D243511 standard test methods for onedimensional consolidation properties of soils using incremental loading one dimensional 1d consolidation test. The consolidation test is also referred to as standard oedometer test or onedimensional compression test. The settlement values obtained by this test are due to primary consolidation only which is 90% of the total consolidation. Initial consolidation it is a comparatively a sudden reduction in soil volume on application of the load mainly due to expulsion and compression of air present in soil pores. Iit gandhinagar, soil mechanics lab page 1 indian institute of technology gandhinagar department of civil engineering soil mechanics laboratory consolidation test oedometer test is 2720part151986 reaffirmed2002 theory. A model which includes the initial compression, the primary consolidation, and the secondary compression is used. Traditionally, the load duration is the same for each increment and equal to 24 h. Swellconsolidation attachment 1 one test for each 20,000cubic yards of zone a fill placed. This test is carried out on saturated soil specimens. Civ e 353 geotechnical engineering i consolidation. Pdf on jun 7, 2015, jaafar mohammed and others published consolidation of soils testing and evaluation find, read and cite all the research you need on researchgate.
It is a time dependent behavior of soil deformation. Ald test confines the soil laterally in a metal ring so that settlement and drainage can occur only in the vertical direction. Consolidation test report cive334 nebraska studocu. Soil mechanics settlement and consolidation page 8. Song due april 10th, 2018 purpose this test is designed to determine the rate and magnitude of volume decrease that a soil sample undergoes when subjected to different vertical loads.
Volume change in saturated soils caused by the expulsion of pore. Consolidation test is used to determine the rate and magnitude of settlement in soils. Recall that a complete consolidation test involves loading a soil specimen in a series of increments. Class 7 consolidation test geotechnical engineering. The exact cause of secondary consolidation is unknown, but is possibly a readjustment of the double water layer surrounding the clay particles.
The triaxial test procedures have been developed from those which are described in soil testing for engineers by t. The data helps to determine the compression and recompression index, coefficient of consolidation and coefficient of secondary. Analysis of results of consolidation tests of saturated. These are discussed in courses on ground modification. Test procedure for consolidation test of soil contains following steps. For some soils, the rate of consolidation is such that complete consolidation dissipation of excess pore pressure will require more than 24 h. Laboratory results demonstrating an apparent lack of creep in the stage of primary consolidation are explained by characteristic features of the generalized. Volume change in saturated soils caused by the expulsion of pore water from loading. First step is to collect the soil specimen using consolidation metal ring. This test is carried out on saturated soil specimens, especially in cohesive soils.
The rate and amount of consolidation with load are usually determined in the laboratory by the onedimensional consol in this test, a laterally confined soil is subjected to successively increased vertical pressure, allowing free drainage from the top and bottom surfaces. Oedometer consolidation test analysis by nonlinear regression. Aasht o t216 and bs 77 part 5 can be carried out using our m anual loading frame, the hm 1 100 or one of the pneumatic loading ma chines, the hm 2432 or. Consolidation of soil is mainly used for clayey soil. Consolidation test soil sample dial gage porous stone porous stone water bath water bath laboratory consolidation test soil sample 25mm2. Consolidation test is used to determine the rate and magnitude of settlement in. Oedometer consolidation test analysis by nonlinear regression abstract. Secondary consolidation slow settlement believed to be due to the movement of soil particles caused by the application of vertical stress to the sample. In case of saturated soil mass the applied stress is. Pore pressure increase dissipates rapidly due to high permeability. In consolidation process, soil volume is reduced by squeezing out pore water from the saturated soil.
Gray 1936 showed that the position of the virgin consolidation curve is a function of. It is also helpful in analyzing the stress history of soil. Similarly, a reduction in temperature may increase ring friction and cause a reduction in the apparent rate of secondary compression. Standard test methods for onedimensional consolidation properties of soils using incremental loading1 this standard is issued under the.
The ring should be clean and dried and its weight, inner diameter and height are measured using weighing balance and calipers respectively. The following results were obtained from an oedometer test carried out on a sample of clay. This increase in pore pressure leads to drainage of some water from the voids of the soil. Consolidation test results are dependent upon the duration of each load increment. Soil mechanics consolidation over consolidated clays now this is where it gets interesting. It is found by subtracting the stress carried by the water in the continuous void spaces i. The data of void ratio e and effective stress were determined after equilibrium had been reached for each applied load. Consolidation test is used to determine the rate and magnitude of soil consolidation when the soil is restrained laterally and loaded axially. It is shown that the dependence of soil deformation on the distance to the drainage boundary, which is noted by a number of experimenters for the stage of secondary consolidation, is explained by incorrect interpretation of test data. Standard test methods for onedimensional consolidation.
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