Large-Size Geotechnical True Triaxial Test System for Multi-Field Coupling
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Solution Overview
Problem
Conventional geotechnical triaxial test systems fail to simulate actual three-dimensional stress conditions and multi-field coupling effects, such as temperature, water, and salt migration, due to their axisymmetric stress state and inability to accommodate large-size soil samples with integrated temperature control and multi-field coupling capabilities.
Innovation Solution
A temperature-controllable large-size geotechnical true triaxial multi-field coupling test system is developed, featuring a deformable soil box with independent three-dimensional loading, refrigeration, and water/salt supplementation units, along with monitoring systems to simulate actual stress states and observe soil-water-ice-salt changes, allowing for the simulation of three-dimensional migration processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional triaxial test systems are used, then the test system structure is simple, but the axisymmetric stress state cannot reflect the complex three-dimensional stress conditions of actual soil
Solution Approach 1:
The patent employs dynamic loading mechanisms with independent actuators for each principal stress direction, enabling the system to transition from static axisymmetric loading to dynamic true triaxial loading. The loading frame incorporates movable components that can independently adjust stress in three directions, transforming the rigid conventional system into a flexible true triaxial system capable of simulating complex stress paths.
Solution Approach 2:
The test system is segmented into independent loading units for each principal stress direction (σ1, σ2, σ3), with separate actuators and control systems. This segmentation allows independent control of each stress component, enabling true triaxial stress states while maintaining modular system architecture that manages complexity through functional decomposition.
2Device complexity
If smaller test samples are used in traditional true triaxial test systems, then the device complexity is reduced, but the scale effect problem makes it impossible to achieve actual multi-field coupling effects
Solution Approach 1:
The patent implements a deformable soil box with adjustable volume and configuration parameters, allowing the sample size to be optimized for specific test requirements. The soil box can be deformed to accommodate different sample dimensions while maintaining the true triaxial stress state, thus enabling large-scale samples that capture actual multi-field coupling effects without requiring overly complex system configurations.
Solution Approach 2:
The test system employs a nested structure where the deformable soil box is positioned within the loading frame, which itself is part of a larger multi-field coupling system. This nesting allows the core soil sample to be surrounded by environmental chambers for temperature, water, and salt control, integrating multiple functions within a hierarchical structure that manages complexity through organized layering.
3Device complexity
If soil test samples are completely packaged or closed at the peripheries, then the test system structure is simplified, but the open state of actual soil cannot be simulated and temperature, water, and salt migration processes cannot be achieved
Solution Approach 1:
The patent employs a deformable soil box with flexible walls that can expand, contract, and deform to accommodate soil sample volume changes during testing. This flexible enclosure replaces rigid closed packaging, allowing the soil to maintain its natural open state while being contained, and enabling integration with environmental chambers for temperature, water, and salt migration studies.
Solution Approach 2:
The deformable soil box serves multiple functions: it contains the soil sample, transmits true triaxial stresses from the loading frame, allows volume deformation during compression, and interfaces with environmental chambers for multi-field coupling. This multi-functional design eliminates the need for separate rigid containment structures while enabling comprehensive environmental simulation.
4Measurement precision
If more sensors are added to smaller test pieces, then the measurement precision improves, but the sensors have greater impact on the performance of test pieces
Solution Approach 1:
The patent uses a limited number of strategically placed sensors within the large soil sample, relying on the sample's inherent heterogeneity to capture representative measurements. Rather than densely distributing many sensors that would disturb the soil structure, the system uses fewer sensors positioned at critical locations, accepting that each measurement represents a localized region while the overall sample behavior is captured through the true triaxial loading and deformable box design.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively simulates the migration of water and salt in large-size soil samples, providing a realistic three-dimensional stress state and multi-field coupling effects, enhancing the accuracy of soil testing and supporting studies on frost damage prevention and disaster control in cold regions.
Implementation Method 1
refrigeration, water and salt supplementation unit... to respectively correspondingly apply stress to the soil box, supplement refrigeration as well as water and salt, and monitor soil-water-ice-salt changes
Implementation Method 2
water supply and drainage trough is arranged on the bottom plate; a water permeation plate is arranged on the water supply and drainage trough... to convey water or salt to the bottom plate through the circulating plate; and the water or salt is permeated from the water supply and drainage trough to the water permeation plate to supplement water or salt to the soil
Data Source
AI summary
The present disclosure discloses a temperature-controllable large-size geotechnique true triaxial multi-field coupling test system and a test method. The system includes a host loading mechanism, a deformable large-size soil box, an independent three-dimensional loading unit, a refrigeration, water and salt supplementation unit, and a soil-water-ice-salt change monitoring unit. The deformable large-size soil box is arranged on the host loading mechanism. In combination with the special structural design, monitoring is carried out by dividing a large-size soil test sample into environmental soil and a core soil region to eliminate the size effect of the test. The solution can simulate a three-dimensional stress state of the soil test sample in a three-dimensional open system. In consideration of the evolution of hydrothermal salt and three-dimensional migration of temperature, water, salt, etc. between the soil and the environment, temperature-water-salt-stress-strain multi-field coupling is realized.