A Determination Method of Elastic-Plastic Yield Point Stress in Repeated Load Test of Graded Crushed Stone
A technology of graded crushed stone and load test, applied in the direction of applying repetitive force/pulsation force to test material strength, strength characteristics, instruments, etc., can solve the problems affecting the evaluation and prediction of long-term performance of structures, unclear status, lack of description and Instructions and other issues to achieve the effect of convenient test methods and parameter acquisition methods, clear representative meanings, and simple calculation processes
Active Publication Date: 2020-06-05
CHANGAN UNIV
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Problems solved by technology
The stress at the yield point is an important judgment to determine when plasticity occurs, and the conventional yield surface also lacks relevant instructions and guidance, and the state of the structure cannot be clarified, which seriously affects the analysis of the structural performance bearing capacity and the evaluation of the long-term performance of the structure. and forecast
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[0053] Taking the graded gravel with interlocking dense skeleton structure as an example, the confining pressure is 10kPa, the axial load strength is 80kPa, 160kPa, 240kPa and 320kPa respectively, and 20000 repeated load tests are carried out respectively.
[0054] According to the calculation method of plastic strain rate and springback strain, the plastic strain rate and springback strain under different load intensities and load times are calculated.
[0055] The plastic strain is judged according to the stability, and the plastic cumulative strain during the period of 3000 to 5000 loads is judged. The judgment results meet the stability requirements, indicating that the graded crushed stone will be in a stable state after a certain number of repeated loads.
[0056] The calculation models of plastic strain rate and springback strain under different load intensities and load times are established. In an embodiment, the calculation model of the plastic strain rate is: The ...
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Abstract
The invention discloses a method for determining the elastic-plastic yield point stress of a repeated load test of graded crushed stones. The method is based on the deformation process of granular materials such as graded crushed stones under repeated loads, and adopts a stability analysis method, through plastic strain Evaluate the stability of graded crushed stone under repeated loads, and establish the plastic strain rate model and rebound strain model of graded crushed stones under repeated loads; through the analysis of plastic strain rate, rebound strain and SMP yield criterion The relationship between yield stress and load intensity and load times is proposed to calculate the model. The invention can determine the yield stress and elastic-plastic state of the pellets under different load intensities and load times, provides conditions for elastic-plastic stress-strain calculation, and lays a foundation for the application of the elastic-plastic model of graded gravel. The invention has the advantages of convenient test method and parameter acquisition method, clear representative meaning of model components, and simple calculation process of elastic-plastic yield point yield stress.
Description
technical field [0001] The invention belongs to the technical field of road engineering, and in particular relates to a method for determining elastic-plastic yield point stress in a repeated load test of graded gravel. Background technique [0002] Graded crushed stone is a typical base or subbase material for road engineering flexible pavement due to its good deformation traceability, crack barrier, water permeability and renewability. However, graded crushed stone has the characteristics of loose particles, weak stress diffusion ability under load, large plastic deformation, and significant elastoplasticity. The use of elastic models for the design and calculation of graded crushed stone structure layer is different from its actual effect. The conventional elastic model is not enough to reflect the characteristics of graded crushed stone, so it is necessary to use an elastic-plastic model to characterize the elastic-plastic characteristics of graded crushed stone. [000...
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IPC IPC(8): G01N3/32
CPCG01N3/32G01N2203/0005G01N2203/0075
Inventor马骉李宁王小庆司伟陈莎莎
OwnerCHANGAN UNIV