Permanent Deformation Models for Soils Using Shift-Factor Master Curves
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for analyzing permanent deformation (PD) of soils and granular materials are time-consuming, requiring 12 business days per material, which limits the geotechnical investigation of highway engineering projects.
Innovation Solution
A permanent deformation model using the Shift Factor (SF) concept, reducing the number of load cycles from 150,000 to 10,000 per stress pair, with the exception of the most severe pair, and constructing master curves to characterize PD, reducing the analysis time to approximately three business days.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If 150,000 load cycles are applied for each stress pair according to current standard, then the permanent deformation analysis is accurate and complete, but the analysis time becomes excessively long (12 business days per material)
Solution Approach 1:
The patent applies partial action by performing tests with only 10,000 load cycles per stress pair instead of the full 150,000 cycles required by current standards. This reduced cycle count is sufficient to capture the essential permanent deformation behavior while avoiding the excessive time consumption of complete cyclic testing. The master curve methodology then extrapolates results to predict long-term performance.
Solution Approach 2:
The patent uses preliminary action by conducting a preliminary assessment with reduced load cycles (10,000 cycles) to establish initial permanent deformation characteristics. These preliminary results are then used to construct master curves that predict long-term behavior without requiring the full 150,000 cycles, thus saving time while maintaining predictive accuracy.
2Reliability
If multiple drill holes and CBR analyses are performed according to DNIT guide for highway foundation quality evaluation, then comprehensive geotechnical investigation is achieved, but the total analysis time becomes prohibitively long (83 days for 1 km section)
Solution Approach 1:
The patent changes the key parameter of load cycle duration by reducing it from 150,000 cycles to 10,000 cycles per stress pair. This parameter change maintains the reliability of permanent deformation assessment while reducing individual test time from 12 business days to approximately 3 business days, thereby enabling comprehensive highway investigations within practical timeframes.
Solution Approach 2:
The patent uses master curves as a copying mechanism, where results from reduced-cycle tests are used to construct master curves that replicate and predict long-term permanent deformation behavior. These master curves serve as simplified copies that capture essential material characteristics without requiring exhaustive long-duration testing for each location.
3Productivity
If the number of load cycles is reduced from 150,000 to 10,000 per stress pair, then the analysis time is significantly reduced, but the accuracy of permanent deformation characterization may be compromised
Solution Approach 1:
The patent applies dynamics by using a flexible testing protocol where 10,000 cycles serve as a dynamic baseline for constructing master curves. The methodology dynamically adapts to different stress pairs and material types, allowing the reduced cycle count to remain valid across various conditions while maintaining characterization accuracy through the master curve framework.
Data Source
AI summary
The present disclosure describes embodiments of a permanent deformation model for soils and granular materials with the application of the Shift Factor (SF) concept. The model was structured following the guidelines provided by the standard DNIT 179, but with the modification of the number of loading cycles and the stress pairs to be applied. Instead of 150,000, 10,000 load cycles were used for each stress pair, with the exception of the most severe pair, for which 150,000 load cycles continued to be applied. From the results obtained for each stress pair, there is constructed a master curve representative of one of the test stress pairs, selected as a reference. Embodiments of the present disclosure finds its field of application in the characterization of the permanent deformation of soils and granular materials.