4.1 Tests performed using this test method provide a detailed record of cone resistance that is useful for evaluation of site stratigraphy, engineering properties, homogeneity and depth to firm layers, voids or cavities, and other discontinuities. The use of a friction sleeve can provide an estimate of soil classification, and correlations with engineering properties of soils. When properly performed at suitable sites, the test provides a rapid means for determining subsurface conditions.

4.2 This test method provides data used for estimating engineering properties of soil intended to help with the design and construction of earthworks, the foundations for structures, and the behavior of soils under static and dynamic loads.

4.3 This method tests the soil in-situ and soil samples are not obtained. The interpretation of the results from this test method provides estimates of the types of soil penetrated. Soil samples from parallel borings may be obtained for correlation purposes, but prior information or experience may preclude the need for borings.

4.4 Electronic cone data (D5778) is generally more reliable and reproducible. Mechanical cone equipment may prove useful when penetrating strong or rocky soils that might damage electronic cone equipment. Mechanical cone equipment typically requires less operator expertise to operate and to properly maintain than electronic cone equipment. However, mechanical cone equipment is not recommended for liquefaction investigations or investigations where a high level of quality assurance must be obtained.

4.4.1 There are many local and regional design guides based solely on mechanical CPT data for estimating engineering properties. It should be remembered, however, that mechanical cone data differ from electrical cones (D5778) because of the geometry of the cone and friction sleeve sections: large differences in R_f (which affects estimated soil type) and smaller differences in tip resistances. Users of these test data are cautioned that engineering property correlations for electronic cones are not to be used with data from mechanical cones.3

Note 1: 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 facility used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/inspection. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some, but not all, of those factors.

1.1 This test method covers the procedure for determining the resistance of a mechanical cone as it is advanced into subsurface soils at a steady rate.

1.2 This test method may also be used to determine the frictional resistance of a cylindrical sleeve located behind the conical point as it is advanced through subsurface soils at a steady rate.

1.3 Mechanical cones of the type described in this test method operate either continually (in which cone penetration resistance is measured while cone and push rods are moving continuously until stopped for the addition of a push rod) or discontinuously (in which cone penetration resistance and, optionally, sleeve friction are measured during a penetration stop of the push rods) using an inner rod system and a cone tip that is telescoping.

1.4 This test method applies to mechanical cones. Field tests using electronic type cones are covered elsewhere by Test Method D5778. The mechanical cone data does not yield the same test results as the electrical penetrometer and the data obtained from it must not be used to estimate engineering properties from engineering guides based on electrical penetrometer (see 4.4.1).

1.5 Cone penetration testing data can be used to interpret subsurface stratigraphy, and through use of site specific correlations, they can provide data on engineering properties of soils intended for use in design and construction of earthworks and foundations for structures.

1.6 Units—The values stated in SI units are to be regarded as 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 nonconformance with this test method.

1.7 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026 unless superseded by this standard.

1.7.1 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 commensurate with these considerations. It is beyond the scope of this standard to consider significant digits used in analysis methods for engineering design.

1.8 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.

1.8.1 When performing cone penetration testing the following actions should be taken:

1.8.1.1 Permit only authorized personnel within the immediate test area, and only as necessary to operate test equipment.

1.8.1.2 Provide a stable and level work area around the thrust machine. Keep all test and adjacent work areas, walkways, platforms, etc., clear of scrap, debris, small tools, and accumulations of snow, ice, mud, grease, oil, or other slippery substances.

1.8.1.3 Prior to beginning a sounding, perform site surveys to ensure hazards such as overhead and underground utilities will not be encountered.

1.9 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.