Technical Specification for Static Loading Test of Self-Balanced Method of Building Foundation Piles

Overview

The Technical Specification for Static Loading Test of Self-Balanced Method of Building Foundation Piles (JGJ/T 403-2017) has been released by the Ministry of Housing and Urban-Rural Development of the People's Republic of China. This specification was approved as an industry standard and will be implemented starting September 1, 2017.

Purpose

This specification aims to ensure safety, accuracy of data, and correct evaluation in the self-balanced static loading tests of building foundation piles.

Scope of Application

This specification applies to the vertical bearing capacity detection and evaluation of foundation piles when traditional static load testing conditions are limited.

Main Technical Content

The key technical content includes: - General Provisions - Terms and Symbols - Basic Requirements - On-site Testing - Data Analysis and Evaluation

Basic Regulations

General Provisions

• The number of self-balanced static loading tests should meet design requirements, with a minimum of 1% of the total number of piles in the same condition, and no less than 3 piles. For projects with fewer than 50 piles, at least 2 piles must be tested.
• Maximum loading values should satisfy the design requirements for single pile ultimate bearing capacity.
• Before conducting self-balanced static loading tests on large diameter cast-in-place piles, acoustic wave transmission integrity testing should be performed first, followed by bearing capacity testing.
• Engineering pile bearing capacity tests should provide the detected bearing capacity value of inspected piles and evaluate whether the single pile bearing capacity meets the design requirements.
• If the single pile bearing capacity does not meet the design requirements, reasons should be analyzed, and after confirmation from relevant parties involved in engineering construction, further testing should be expanded.
• After completing the bearing capacity test of engineering piles, grouting treatment should be carried out at the position of the load cell.

Testing Procedures

• Testing work should ideally follow the procedure: acceptance of commission, collection of data, formulation of plans, equipment installation and pile formation, on-site testing, data analysis and result evaluation, and preparation of the testing report.
• Testing institutions should develop a testing plan based on collected data, which should include:
• Project overview, geological conditions, pile design requirements, construction methods, testing quantity, principles for selecting inspected piles.
• Specifications, quantities, burial positions, and maximum loading values of load cells.
• Requirements for inspected pile construction, testing schedule, and mechanical or labor resources needed.

Terminology and Symbols

• Self-Balanced Static Loading Test: A method that utilizes a load cell pre-buried within the pile to achieve balance between the self-weight of the upper part of the pile, the ultimate side friction resistance, and the ultimate end resistance.
• Load Cell (LoaDBox): Used in self-balanced static loading tests to apply loads.
• Equivalent Conversion Method: Converts the load-displacement curve of the load cell under upward and downward loads in self-balanced static loading tests into equivalent traditional static loading tests.
• Balanced Point: The location where the sum of the self-weight of the upper part of the pile and the ultimate side friction resistance is equal to the ultimate end resistance of the lower part of the pile.

References and Appendices

• Appendix A: Technical Requirements for Load Cells
• Appendix B: Measurement of Internal Forces in Pile Shafts
• Appendix C: Installation and Connection of Testing Systems
• Appendix D: Record Sheets for Self-Balanced Static Loading Tests
• Appendix E: Equivalent Conversion Methods

Usage Instructions and Quoted Standards

• Explanation of wording in this specification
• List of quoted standards

This specification provides detailed guidelines and technical specifications for the safe and accurate execution of self-balanced static loading tests for building foundation piles.