Gradient Thermal Conductivity Pavement for Frozen Soil Subgrade
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Solution Overview
Problem
Current subgrade protection measures for highways in frozen soil areas are ineffective and costly, with issues such as uneven temperature distribution, heat accumulation, and maintenance challenges, leading to instability and deformation of the subgrade.
Innovation Solution
A pavement structure with gradient thermal conductivity, comprising multiple layers with varying thermal conductivity arranged in descending order, utilizing micro nano powders to manage heat transfer and dispersion, preventing heat from accumulating in the subgrade and permafrost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If subgrade lifting technique is adopted to protect highway subgrade in frozen soil area, then the subgrade stability is improved, but the construction cost and complexity increase significantly
Solution Approach 1:
The invention changes the thermal conductivity parameter of the pavement structure by incorporating phase change materials and designing multi-layer structures with different thermal properties. This allows the pavement to actively regulate heat transfer, preventing heat accumulation in the subgrade without requiring complex construction techniques like subgrade lifting, thereby maintaining subgrade stability while reducing construction complexity
Solution Approach 2:
The invention introduces phase change materials as intermediary substances between the pavement surface and the subgrade. These materials act as thermal buffers that absorb and release heat during phase transitions, mediating the heat transfer process to protect the subgrade from temperature fluctuations without requiring complex structural modifications
2Temperature
If ventilation tube technique is used to cool the subgrade, then the heat transfer effect is improved, but the side slope area increases and shady-sunny effect occurs reducing effectiveness
Solution Approach 1:
The invention extracts the heat transfer function from the complex ventilation tube system and implements it directly within the pavement structure itself. By integrating phase change materials and thermal conductivity layers into the pavement, the heat transfer mechanism is simplified and made more effective without requiring additional side slope area or creating shady-sunny effects
3Temperature
If block stone subgrade technique is applied to cool the subgrade, then the cooling effect at slope foot is improved, but the middle part temperature remains high causing uneven deformation
Solution Approach 1:
The invention applies local quality by designing multi-layer pavement structures with different thermal conductivity properties tailored to specific locations and depths. Phase change materials are strategically positioned to address local thermal conditions, ensuring uniform temperature distribution throughout the subgrade and preventing uneven deformation while maintaining overall subgrade stability
4Ease of operation
If asphalt pavement is used in frozen soil area, then the road surface performance is improved, but heat accumulation occurs in the subgrade during cold seasons
Solution Approach 1:
The invention changes the thermal parameters of the pavement structure by incorporating phase change materials and designing multi-layer configurations with varying thermal conductivity. This modifies the energy storage and release characteristics of the pavement, allowing it to perform well as a road surface while preventing harmful heat accumulation in the subgrade during cold seasons
Solution Approach 2:
The invention converts the heat accumulation problem into a beneficial thermal regulation mechanism. Phase change materials absorb excess heat during warm periods and release it during cold periods, transforming what was previously a harmful effect (heat accumulation) into a useful function (active thermal management) that protects the subgrade while maintaining road surface performance
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 solution effectively disperses heat during warm seasons and releases it during cold seasons, maintaining subgrade stability, reducing thaw layer thickness, and lowering construction and maintenance costs while enhancing the operational capability of highways in frozen soil areas.
Implementation Method 1
a pavement structure with gradient thermal conductivity, comprising multiple layers with varying thermal conductivity arranged in descending order, utilizing micro nano powders to manage heat transfer and dispersion
Implementation Method 2
The solution effectively disperses heat during warm seasons and releases it during cold seasons, maintaining subgrade stability
Data Source
AI summary
The present invention provides a method and pavement structure for protecting highway subgrade in frozen soil areas. The pavement structure has two or more pavement layers having gradient thermal conductivity; the thermal conductivity is layered among the pavement layers and is lowered from top to bottom, so that the pavement forms a uni-directional thermal conducting tunnel from the subgrade to the air. Heat can be easily released from the subgrade into the air, and is prevented from being transferred from the air to the subgrade. In this way, the frozen soil layer beneath the subgrade is cooled, so that the frozen soil table is made stable, and the highway subgrade in frozen soil areas is protected.