定价： 1775元 / 折扣价： 1509 元

定价： 1001元 / 折扣价： 851 元

5.1 The ring shear apparatus maintains the cross-sectional area of the shear surface constant during shear and shears the specimen continuously in one rotational direction for any magnitude of shear displacement and along the entire specimen cross-sectional area.5.2 The ring shear apparatus allows a reconstituted specimen to be consolidated at the desired normal stress prior to drained shearing. This simulates the field conditions under which complete softening develops in overconsolidated clays, claystones, mudstones, and shales that do not have a pre-existing shear surface, sheared bedding planes, joints, or faults as described by Skempton (19702 and 19773) and unfailed compacted fill slopes (Gamez and Stark 20144) because the fully softened strength corresponds to the peak shear strength of a normally consolidated fine-grained soil. The fully softened strength is only applicable to the soil zones that are subject to the environmental deterioration and applied shear stresses that lead to soil softening, deterioration of soil fabric, and strength loss, which may not be relevant to all slopes and all depths. The fully softened strength should be used in an effective stress/drained stability analysis using a stress dependent strength envelope for slopes with no prior shearing.5.3 The ring shear test is suited to the determination of the drained fully softened shear strength because of the short drainage path through the thin specimen, small post-peak strength loss in a normally consolidated specimen, and the constant cross-sectional area.5.4 The ring shear test specimen is annular so the angular displacement differs from the inner radius to the outer radius. This is not significant because a normally consolidated specimen does not exhibit a large post-peak strength loss so the difference in peak shear resistance at the inner radius and outer radius at different displacements is not significant and the ratio of the inner to outer radii of the ring is greater than 0.5 in accordance with Hvorslev (1936)6.NOTE 1: Notwithstanding the statements on precision and bias contained in this test method: The precision of this test method 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 testing. Users of this test method are cautioned that compliance with Practice D3740 does not ensure reliable testing. Reliable testing depends on several factors; Practice D3740 provides a means of evaluating some of those factors.1.1 This test method provides a procedure for performing a torsional ring shear test under a drained condition to measure the fully softened shear strength and stress dependent strength envelope of fine-grained soils (using a reconstituted normally consolidated specimen). The fully softened strength and the corresponding stress dependent effective stress strength envelope are used to evaluate the stability of slopes that do not have a pre-existing shear surface but have been subjected to environmental conditions and shear stresses that lead to soil softening, deterioration of the soil fabric, and strength loss. It has been shown (Skempton 19702 and 19773) that under these conditions and within the depth zones that have undergone softening, first-time slope failures can occur at effective stress levels that correspond to a fully softened strength envelope. It has also been shown empirically (Skempton 19702 and 19773) that fully softened strength of fine grained soils can be approximated by the peak strength of a reconstituted and normally consolidated specimen. In this test method, reconstituted and normally consolidated specimens are sheared at a controlled and constant displacement rate until the peak shear resistance has been obtained. Generally, the drained fully softened failure envelope is determined at three or more effective normal stresses. A separate test specimen must be used for each normal stress to measure the fully softened strength otherwise a post-peak or even drained residual strength will be measured if the same specimen is used at the same or at another effective normal stress because of the existence of a prior shear surface.1.2 The ring shear apparatus allows a reconstituted specimen to be normally consolidated at the desired normal stress prior to drained shearing. The test results closely simulate the fully softened strength of stiff natural fine-grained soils (Skempton 19702 and 19773) and compacted fills of fine-grained soils (Gamez and Stark 20144). This simulates the mobilized shear strength in overconsolidated clays, claystones, mudstones, and shales in natural slopes and compacted fill in manmade slopes, such as, dams, levees, and highway embankments, after the soil has fully softened and attained the fully softened strength condition.1.3 A shear stress-displacement relationship may be obtained from this test method. However, a shear stress-strain relationship or any associated quantity, such as modulus, cannot be determined from this test method because defining the height of the shear zone is difficult and needed in the shear strain calculations. As a result, the height of this shear zone is unknown, so an accurate or representative shear strain can therefore not be determined.1.4 The selection of normal stresses and final determination of the shear strength envelope for design analyses and the criteria to interpret and evaluate the test results are the responsibility of the engineer or entity requesting the test.1.5 Units—The values stated in SI units are to be regarded as the standard. The values given in parentheses are mathematical conversions to inch-pound units that are provided for information only and are not considered standard.1.6 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.1.7 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.

定价： 590元 / 折扣价： 502 元 加购物车

4.1 The principle of measurement is based upon a reversible isothermal change in apparent viscosity with change in rate of shear produced by a change in rotational speed.4.2 Measurement is performed with a rotational viscometer under standardized conditions with rigid control of the time intervals of measurement. Viscosity readings are obtained at the end of 1 min for each rotational speed. Changes from the lowest speed to the highest speed, and return to the lowest speed, are made without stopping the instrument.1.1 This test method covers the measurement of the apparent viscosity of shear-rate-dependent adhesives using a rotational viscometer.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 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.1.4 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.

定价： 515元 / 折扣价： 438 元 加购物车

5.1 The performance characteristics of a drainage geosynthetic are directly related to the integrity under compressive loading. If the product is sensitive to compressive deformation, its flow capacity could be greatly reduced or even shut off completely.5.2 The deformation sensitivity of a candidate geosynthetic can be tested at field-simulated normal stress and potential tangential stresses.5.3 This test method does not evaluate the effect of deformation of a geotextile filter or adjacent membrane.5.4 Compression deformation, as it relates to reduction in flow capacity of a geosynthetic drainage product, is manufacturer and product specific. For example, a 10 % reduction in original thickness of a geonet made by Manufacturer A does not necessarily equal the same reduction in flow capacity as a 10 % reduction in thickness of the same or another type of geonet made by Manufacturer B.5.5 This deformation data has merit directly to the end user, because it can be easily interpreted to result in a reduction factor for compressive deformation.4 The reduction factor can then be used to derive an allowable flow rate.51.1 This test method is used to determine the unconfined compressive deformation (consolidation) characteristics of drainage geotextiles, geocomposites, geonets, or any other geosynthetic associated with drainage at a constant temperature, when subjected to a constant compressive stress.1.2 This test method is intended for use as an unconfined compressive performance deformation test only. For a detailed procedure on how to establish an index test, see EN ISO 25619-1. For performance tests, the specimen shall be subjected to the site-specific liquid, the site-specific stress (normal and potentially a tangential stress on the upper and parallel loading platen), or both.NOTE 1: Results achieved from unconfined compressive performance deformation testing may differ from testing performed under confined conditions.1.3 Because of the changing nature of the geosynthetic industry and the wide variety of products already available, this particular test method may have to be slightly modified for unconfined compression deformation testing of some products.1.4 The values given in SI units are to be considered as the standard. The values given in parentheses are for information only.1.5 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.1.6 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.

定价： 515元 / 折扣价： 438 元 加购物车

5.1 The intent of this test method is to determine the time dependence of modulus in building joint sealants using two loading-unloading cycles to identify and mitigate any Mullins effect, and followed by a stress relaxation procedure to determine the time dependent modulus.5.2 This test method has found applications in screening the performance of building joint sealants since the modulus is one indicator of the ability of elastomeric building sealant to withstand environmental induced movements.1.1 This test method covers a procedure for measuring the time dependence of modulus in elastomeric joint sealants in a test specimen configuration described in Test Method C719. These sealant materials are typified by highly filled rubber materials. Any Mullins effect is first assessed and mitigated in two loading-unloading cycles. Time dependence of modulus in materials is then determined using a stress relaxation procedure.1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.1.3 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.1.4 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.

定价： 515元 / 折扣价： 438 元 加购物车

CSA Preface This is the second edition of CAN/CSA-Z10651-2, Lung ventilators for medical use - Particular requirements for basic safety and essential performance - Part 2: Home care ventilators for ventilator-dependent patients, which is an adoption, w

定价： 1092元 / 折扣价： 929 元