Significance and Use
5.1 This test method provides a radial stress-strain response of the soil in situ. A pressuremeter modulus and a limit pressure are obtained for use in geotechnical analysis and foundation design. Correlations of the test results to soil strength and stiffness and to engineering design applications are generally empirical, and deviation from the methodology described in this test method may have undesirable effects.
Note 5: As with other in situ and laboratory test methods, the user should consider whether results from this test are appropriate for the intended design use. Considerations may include whether the test directly measures strength or stiffness, the orientation of loading, the level of induced strain, insertion or borehole disturbance effects, soil sensitivity, soil saturation, drainage effects, and the robustness of the test equipment, etc.
5.2 The results of this test method are dependent on the clearance between the test cavity and probe and the degree of ground disturbance caused by test cavity preparation and probe insertion, all of which shall be considered during interpretation of the test results. This disturbance is particularly significant in very soft clays and very loose sands. Disturbance may not be eliminated completely but shall be minimized for the prebored pressuremeter design rules to be applicable.
Note 6: The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/ inspection/etc. Users of this test method are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.
Scope
1.1 This test method covers pressuremeter testing of soils at a given depth in the ground within a suitable prebored, open test cavity. The pressuremeter test is an in situ, stress-strain test performed on the wall of a test cavity using a circular cylindrical probe that is expanded radially. To obtain viable test results, disturbance of the test cavity must be minimized with minimal clearance between the diameter of the probe and the test cavity. Alternatively, when preboring does not provide an acceptable test cavity, the probe may be directly inserted into the ground to form the test cavity.
1.2 This test method includes the procedure for test cavity preparation, inserting the probe, and conducting pressuremeter tests in both granular and cohesive soils, but does not include high pressure testing in rock. Knowledge of the type of soil to be tested is necessary for assessment of (1) the method of preparing the test cavity, (2) the interpretation of the test data, and (3) the acceptability of the test results.
1.3 This test method does not cover the self-boring pressuremeter, for which the hole is drilled by a mechanical or jetting tool inside the hollow core of the probe. This test method is limited to the type of pressuremeter that is inserted into predrilled boreholes or, under certain circumstances, is inserted by driving or pushing.
1.4 Two alternative testing procedures are provided as follows:
1.4.1 Procedure A—Equal Pressure Increments
1.4.2 Procedure B—Equal Volume Increments
Note 1: Pressuremeter tests performed in rock or using the self-boring pressuremeter follow similar test procedures to those described herein, but do not fall within the scope of this test method.
Note 2: Strain-controlled tests also can be performed, whereby the probe volume is increased at a constant rate and corresponding pressures are measured. Strain-controlled tests may yield different results than the procedures described in this test method.
1.5 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026.
1.6 The procedures used to specify how data are collected/recorded and calculated in this standard are regarded as the industry standard. In addition, they are representative of the significant digits that should generally be retained. The procedures used do not consider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the user’s objectives; and it is common practice to increase or reduce significant digits of reported data to be commensurate with these considerations. It is beyond the scope of this standard to consider significant digits used in analysis methods for engineering design.
1.7 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard.
1.8 The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard. Reporting of test results in units other than SI shall not be regarded as non-conformance with this test method.
1.9 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.10 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
