ASTM D7702/D7702M-14(2021) PDF
Standard Guide for Considerations When Evaluating Direct Shear Results Involving Geosynthetics
Standard Guide for Considerations When Evaluating Direct Shear Results Involving Geosynthetics
- Статус документа:
- Действующий
- Формат:
- Электронный (PDF)
- Количество страниц:
- 11
- Дата публикации:
- 1 августа 2021 г.
- Издание:
- D7702/D7702M
- ICS:
- 59.080.70
SIGNIFICANCE AND USE 4.1 The shear strength of soil-geosynthetic interfaces and geosynthetic-geosynthetic interfaces is a critical design parameter for many civil engineering projects, including, but not limited to: waste containment systems, mining applications, dam designs involving geosynthetics, mechanically stabilized earth structures, reinforced soil slopes, and liquid impoundments. Since geosynthetic interfaces often serve as a weak plane on which sliding may occur, shear strengths of these interfaces are needed to assess the stability of earth materials resting on these interfaces, such as a waste mass or ore body over a lining system or the ability of a final cover to remain on a slope. Accordingly, project-specific shear testing using representative materials under conditions similar to those expected in the field is recommended for final design. Shear strengths of geosynthetic interfaces are obtained by either Test Method D5321/D5321M (geosynthetics) or D6243/D6243M (geosynthetic clay liners). This guide touches upon some of the issues that should be considered when evaluating shear strength data. Because of the large number of potential conditions that could exist, there may be other conditions not identified in this guide that could affect interpretation of the results. The seemingly infinite combinations of soils, geosynthetics, hydration and wetting conditions, normal load distributions, strain rates, creep, pore pressures, etc., will always require individual engineering evaluations by qualified practitioners. Along the same lines, the list of references provided in this guide is not exhaustive, nor are the findings and suggestions of any particular reference meant to be considered conclusive. The references and their related findings are presented herein only as examples available in the literature of the types of considerations that others have found useful when evaluating direct shear test results. 4.2 The figures included in this guide are only examples intended t... SCOPE 1.1 This guide presents a summary of available information related to the evaluation of direct shear test results involving geosynthetic materials. 1.2 This guide is intended to assist designers and users of geosynthetics. This guide is not intended to replace education or experience and should only be used in conjunction with professional judgment. This guide is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project’s many unique aspects. Not all aspects of this practice may be applicable in all circumstances. The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus process. 1.3 This guide is applicable to soil-geosynthetic and geosynthetic-geosynthetic direct shear test results, obtained using either Test Method D5321/D5321M or D6243/D6243M. 1.4 This guide does not address selection of peak or large-displacement shear strength values for design. References on this topic include Thiel (1),2 Gilbert (2), Koerner and Bowman (3), and Stark and Choi (4). 1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined. 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 standardizatio...
Abstract
Overview
ASTM D7702/D7702M-14(2021), Standard Guide for Considerations When Evaluating Direct Shear Results Involving Geosynthetics, is a comprehensive reference developed by ASTM International. This standard offers guidance for interpreting direct shear test data relating to soil-geosynthetic and geosynthetic-geosynthetic interfaces. The shear strength of these interfaces is a critical parameter in civil and geotechnical engineering, especially when designing and evaluating structures such as waste containment systems, mining facilities, dams, reinforced soil slopes, mechanically stabilized earth structures, and liquid impoundments.
Given that geosynthetic interfaces often serve as potential slip planes, it is vital to accurately evaluate their shear strength using relevant direct shear test methods (such as ASTM D5321/D5321M and D6243/D6243M). ASTM D7702/D7702M provides important considerations and issues to be addressed during the testing and data interpretation process, helping engineers ensure the integrity and safety of their designs.
Key Topics
- Shear Strength Evaluation: Guidance on the significance of shear strength at soil-geosynthetic and geosynthetic-geosynthetic interfaces, including best practices for laboratory testing.
- Direct Shear Testing: Recommendations for conducting project-specific shear testing under representative field conditions, and interpreting results using methods like ASTM D5321/D5321M and D6243/D6243M.
- Interpretation of Test Data: Discussion on interpreting peak versus post-peak (large displacement) shear strength values, understanding Mohr-Coulomb parameters (cohesion and friction angle), and caution against extrapolating outside the tested normal stress range.
- Practical Considerations: Importance of reviewing shear-displacement curves for understanding failure modes (brittle vs. ductile behavior), ensuring quality tests, and identifying specimen or test setup issues.
- Variability and Project Specificity: Acknowledgement of the variability inherent in geosynthetic materials, soils, hydration conditions, strain rates, and other field and lab parameters. Emphasis on the need for engineering judgement and case-by-case evaluation.
- Reporting and Documentation: Best practices for summarizing and reporting direct shear test results to support design and construction documentation.
Applications
ASTM D7702/D7702M serves a broad range of geotechnical and civil engineering applications where geosynthetics are used to contain, reinforce, protect, or stabilize soils and waste materials. Typical uses include:
- Waste Containment Systems: Landfills, hazardous waste facilities, and environmental protection barriers where geosynthetics form critical containment layers.
- Mining Applications: Heap leach pads, tailings dams, and other mining earthworks requiring stable containment over geosynthetic liners.
- Dams and Impoundments: Design and analysis of water retention structures involving geosynthetic clay liners (GCLs) or geomembranes.
- Reinforced Soil Slopes and Mechanically Stabilized Earth (MSE) Structures: Stability analysis of slopes and retaining walls that utilize geotextile or geogrid reinforcement layers.
- Slope Stability: Assessment of potential slip surfaces in natural and engineered slopes where weak geosynthetic interfaces are present.
By following the guidance in this ASTM standard, designers and engineers can better ensure the safety, reliability, and performance of geosynthetic applications under project-specific loading and environmental conditions.
Related Standards
- ASTM D5321/D5321M: Standard Test Method for Determining the Shear Strength of Soil-Geosynthetic and Geosynthetic-Geosynthetic Interfaces by Direct Shear.
- ASTM D6243/D6243M: Standard Test Method for Determining the Internal and Interface Shear Strength of Geosynthetic Clay Liner by the Direct Shear Method.
- ASTM D653: Terminology Relating to Soil, Rock, and Contained Fluids.
- ASTM D4439: Terminology for Geosynthetics.
These standards work in conjunction to provide a complete framework for geosynthetic direct shear testing and data interpretation, supporting the implementation of ASTM D7702/D7702M in geotechnical engineering projects.
Keywords: ASTM D7702, geosynthetics, direct shear, shear strength, soil-geosynthetic interface, geotechnical engineering, slope stability, waste containment, test methods, civil engineering.
Технические детали
- Технический комитет
- D35 - Geosynthetics
- SKU
- ASTM D7702/D7702M-14(2021)
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