【国外标准】 Standard Test Method for Field Vane Shear Test in Saturated Fine-Grained Soils

5.1 This test method provides an indication of in-situ undrained shear strength of saturated fine-grained soils (clays and silts) or other saturated fine-grained geomaterials, such as mine tailings and organic muck. The test is applicable to soils with undrained strengths of less than 200 kPa [2 tsf]. Very sensitive soils can be remolded during vane insertion.5.2 This test method is used extensively in a variety of geotechnical explorations to evaluate rapid loading strength for total stress analysis of saturated fine-grained clays and silts. Since vane shear strength values are most always higher than field strengths for analyses (5.3) they often are checked or compared with other methods of measuring undrained shear strength. Cone Penetrometer Tests (Test Method D5778) and Unconsolidated Undrained Triaxial Compression (D2850) tests are most often performed for direct comparison to the vane shear strength data. Unconfined Compression (D2166/D2166M) testing could also be performed, but suffers from many possible errors from disturbance especially in fissured clays, and should only be performed with experience. For more information on how these tests are used for soft ground site exploration refer to Ladd and DeGroot.(1)45.3 The peak undrained shear resistance of the vane test is commonly corrected to determine the undrained shear strength for geotechnical analysis. The agency requesting the testing must interpret these data to determine applicability for strength analysis. It is beyond the scope of this standard to recommend applicability of vane testing for geotechnical analysis. For information on the general use of these correction factors, consult Appendix X1.5.4 This method is not applicable in unsaturated soils or in non-plastic silts, sands, gravels, or other high permeability soils. With the shearing rates described in this standard, sand lenses, if present, will allow total or partial drainage. Unsaturated soils and soils with higher permeability, in rapid shear, can dilate or collapse and generate negative or positive pore pressures which may, or may not, dissipate in the shearing process. It is important to check the soil type being tested. It is very beneficial to sample the soil either before or after testing, to understand the drainage conditions (permeability) of the soil tested.5.5 This method also applies to hand held vane shear tests performed at shallow depths, however, hand held equipment may be less accurate, because it may be more difficult to maintain vane/rod stability and verticality.NOTE 2: 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. Users of this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable results depend on many factors; Standard Practice D3740 provides a means of evaluating some of those factors.1.1 This test method covers the field vane test in saturated clay and silt soils for determination of undrained shear strength. Knowledge of the nature of the soil in which each vane test is to be made is necessary for assessment of the applicability and interpretation of the test. The test is not applicable for sandy soils or non-plastic silts, which may allow drainage during the test.1.2 This test method addresses testing on land and for testing in drill holes or by self-drilling or continuous push methods from the ground surface. This method does not address specifically marine testing where special test requirements or variations in equipment may be required. The user is referred to ASTM STP 1014 for additional information on in-place vane shear testing used in marine exploration.21.3 This method is often used in conjunction with fluid rotary drilling (D5783), hollow-stem augers (D6151/D6151M), or cone penetration testing (D5778). Some apparatuses have the vane retracted in a protective shoe for advancement and incremental testing. Sampling, such as with thin wall tubes (D1587/D1587M) is often combined with vane testing. Subsurface geotechnical explorations are reported in accordance with Practice (D5434).1.4 Undrained shear strength and sensitivity of cohesive soils can also be measured in Laboratory Vane Test (D4648/D4648M).1.5 Units—The values stated in either SI units or inch-pound units [presented in brackets] are to be regarded separately as standard. The values 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. Reporting of test results in units other than SI shall not be regarded as nonconformance with this test method.1.5.1 The gravitational system of inch-pound units is used when dealing with inch-pound units. In this system, the pound (lbf) represents a unit of force (weight), while the unit for mass is slugs. The rationalized slug unit is not given, unless dynamic (F = ma) calculations are involved.1.6 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026.1.6.1 The procedures used to specify how data are collected/ recorded or calculated in this standard are regarded as the industry standard. In addition they are representative of the significant digits that generally should 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 or reported data to be commensurate with these considerations. It is beyond the scope of this standard to consider significant digits used in analytical methods for engineering design.1.7 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 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.