Soil Property Test Device with Helical Water Flow Groove
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Solution Overview
Problem
Current test devices for unsaturated soil face challenges in accurately determining air entry value and hysteresis curves due to issues like water pressure gradients, bubble interference, and sample disturbance, leading to inaccurate soil water characteristic curve measurements.
Innovation Solution
A test device with a closeable cavity and a water flow groove system where the water inlet is higher than the outlet, utilizing a helical-shaped water flow groove and a vacuum saturation method to minimize water pressure effects and automate bubble discharge, ensuring zero water pressure gradient during testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the drainage water measuring tube is fixed on the bench with initial liquid level 20-30 cm higher than the soil sample, then the apparatus structure is simple, but water pressure of 2-3 KPa is produced below the soil which significantly influences test precision of air entry value
Solution Approach 1:
The device divides the water supply system into two independent parts: a water tank elevated on a stand providing potential energy, and a separate drainage water measuring tube connected to the water outlet. This segmentation allows the measuring tube to be positioned at the same level as the soil sample, eliminating water pressure errors while maintaining structural simplicity through functional separation.
2Reliability
If bubbles are discharged by means of repeated washing, then bubbles are removed from the base, but operation steps become more cumbersome and test work difficulty increases
Solution Approach 1:
The device incorporates a water inlet that extends to the bottom of the base, enabling automatic bubble discharge through preliminary water supply action. When water flows through the base during saturation, it automatically carries bubbles out through the water outlet, eliminating the need for repeated manual washing operations and reducing test work difficulty.
3Quantity of substance
If the water inlet is positioned to provide adequate water supply, then saturation is achieved, but water pressure gradient is created affecting test accuracy
Solution Approach 1:
The water tank is elevated on a stand to provide sufficient water supply through gravitational potential energy, while the drainage water measuring tube is positioned at the same level as the soil sample. This creates an equipotential condition where no water pressure gradient exists during saturation, ensuring accurate soil water characteristic curve measurements while maintaining adequate water supply.
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
This design enhances the accuracy of air entry value and hysteresis curve determination by eliminating water pressure errors and automating bubble removal, improving the precision of soil water characteristic curve measurements.
Implementation Method 1
the water inlet is higher than the outlet, utilizing a helical-shaped water flow groove and a vacuum saturation method to minimize water pressure effects
Implementation Method 2
utilizing a helical-shaped water flow groove and a vacuum saturation method to minimize water pressure effects
Data Source
AI summary
A test device including a closeable cavity and a water flow groove with a water transmission channel existing between the water flow groove and the internal part of the cavity. The water flow groove includes a water inlet and a water outlet with the depth of the water inlet being greater than the depth of the water outlet. Simultaneously, side lead-in pipe of drain pipe and elbow pipe on side wall of water inlet pipe are consistent with height of top surface of the ceramic plate, making hydraulic pressure of tested soil sample being zero during dehydrating and soaking process capable of ensuring accuracy of test result. A necking design is applied to reduce water evaporation in the drainage pipe and lower the test errors. Side lead-in pipe is connected with drainage pipe for smoothly draining water and also can prevent air reversely flowing and entering into the base.