Standard Test Method for One-Dimension Consolidation Properties of Soil Using Incremental Loading. GeoTesting Express is a provider of Soil Testing Services – ASTM D, Standard Test Method for One-Dimensional Consolidation Properties of Soils. Buy ASTM D TEST METHODS FOR ONE-DIMENSIONAL CONSOLIDATION PROPERTIES OF SOILS USING INCREMENTAL.
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The data from the consolidation test are used to estimate the magnitude and rate of both differential and total settlement of a structure or earthfill. Estimates of this type are of key importance in the design of engineered structures and the evaluation of their performance.
The test results can be greatly affected by sample disturbance. Careful selection and preparation of test specimens is required to reduce the potential of disturbance effects. Note 3—Notwithstanding the statement on precision and bias contained in this standard, d243 precision of this test method is dependent on the competence of the personnel performing the test and suitability of the equipment and facilities used.
Agencies that meet the criteria of Practice D generally are considered capable of competent and objective testing. Users of this f2435 method are cautioned that compliance with Practice D does not assure reliable testing. Reliable testing depends on many factors, and Practice D provides a means of evaluation some of these factors. Consolidation test results are dependent on the magnitude of the load increments.
Traditionally, the axial stress is doubled for each increment resulting in a load increment ratio of 1. For intact samples, this loading procedure has provided data from which estimates of the preconsolidation stress, using established interpretation techniques, compare favorably with field observations.
Other loading schedules may be used to model particular field conditions or meet special requirements. For example, it may be desirable to inundate and load the specimen in accordance with the wetting or loading pattern expected in the field in order to best evaluate the response. Load increment ratios of less than 1 may be desirable for soils that are highly sensitive or whose response is highly dependent on strain rate.
The interpretation method specified by these test methods to estimate the preconsolidation stress provides a simple technique to verify that one set of time readings are taken after the xstm stress and that the specimen is loaded to a sufficiently high stress level. Several other evaluation techniques exist and may yield different estimates of the preconsolidation stress.
Alternative techniques to estimate the preconsolidation stress may be used when agreed to by the requesting agency and still be in conformance with these test methods. Consolidation test results are dependent upon the duration of each load increment. Traditionally, the load duration is the same for each increment and equal to 24 h. For some soils, the rate of consolidation is such that complete consolidation dissipation of excess pore pressure will require more than 24 h.
The apparatus in general use does not have provisions for formal verification of pore pressure dissipation. It is necessary to use an interpretation technique which indirectly determines that consolidation is essentially complete.
These test methods specify procedures for two techniques Method A and Method Bhowever alternative techniques may be used when agreed to by the requesting agency and still be in conformance with these test methods.
The apparatus in general use for these test methods do not have provisions for verification of saturation. Most intact samples taken from below the water table will be saturated. However, the time rate of deformation is very sensitive to degree of saturation and caution must be exercised regarding estimates for duration of settlements when atm saturated conditions prevail. Inundation of the test specimen does not significantly change the degree of saturation of the test specimen but f2435 provides boundary water to eliminate negative pore pressure associated with sampling and prevents evaporation during the test.
The extent to which partial saturation influences the test results may be a part of the test evaluation and may include application of theoretical models other than conventional consolidation theory. Alternatively, the test may be performed using an apparatus equipped to saturate the specimen.
ASTM D Standard
These test methods use conventional aatm theory based on Terzaghi’s consolidation equation to compute the coefficient of consolidation, c v. The analysis is based upon the following assumptions:. The compressibility of soil particles and pore water is negligible compared to the compressibility of the soil skeleton. Two alternative procedures are provided as follows:.
Time-deformation readings are required on a minimum of two load increments. This test method provides only the compression curve of the specimen and the results combine both primary consolidation and secondary compression deformations. This test method provides the compression curve asstm explicit data to account for secondary compression, the coefficient of consolidation for saturated materials, and the rate of secondary compression. Note 1—The determination of the rate and magnitude of consolidation of soil when it is subjected to controlled-strain loading is covered by Test Method D Evaluation techniques specified in these test methods assume the pore space is fully saturated and are generally applicable to soils naturally sedimented in d24355.
Tests performed on other unsaturated materials such as compacted and residual weathered or chemically altered soils may require special evaluation satm. In particular, the rate of consolidation interpretation of the time curves is only applicable to fully saturated specimens.
The required maximum stress level depends on the purpose of the test and must be agreed on with the requesting agency. In the absence of specific instructions, Section 11 provides the default load dd2435 and load duration schedule for a standard test.
Note astk readings are required to determine the time for completion of primary consolidation and for evaluating the coefficient of consolidation, c v. Since c v varies with stress level and loading type loading or unloadingthe load increments with timed readings must be selected with specific reference to the individual project.
Alternatively, the requesting agency may specify Test Method B wherein the time-deformation readings are taken on all load increments. Equipment is available to perform consolidation tests using back pressure saturation. The addition of back pressure saturation does not constitute non-conformance to these test methods. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other.
Combining values from the two systems may result in non-conformance with the standard. This implicitly combines two separate systems of units, that is, the absolute system and the gravimetric system.
It is scientifically undesirable to combine two separate systems within a single standard. This test method has been written using SI units; however, inch-pound conversions are given in the gravimetric system, where the pound lbf represents a unit of force weight. How one applies the results obtained using this standard is beyond its scope.
It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. Two alternative procedures are provided as follows: Link to Active This link will always route to the current Active version of the standard.