Effective Stress Cell for Saturated Soil Measurement
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Solution Overview
Problem
Conventional methods for measuring effective stress in saturated soil require separate transducers for pore-water pressure and total earth pressure, leading to errors and increased complexity and costs.
Innovation Solution
An effective stress cell with a sensing diaphragm and a porous diaphragm that allows pore-water to balance pressures, using a strain sensor to directly measure effective stress without measuring pore-water pressure, enabling direct and accurate measurement of effective stress using a single diaphragm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate transducers are used to measure pore-water pressure and total earth pressure, then the measurement can be performed, but measurement errors occur and the process becomes complicated with increased equipment and installation costs
Solution Approach 1:
The patent combines the measurement of pore-water pressure and total earth pressure into a single integrated effective stress cell. The cell uses one diaphragm that simultaneously responds to both pressures, eliminating the need for separate transducers and simplifying the measurement system while maintaining accuracy through direct measurement of effective stress.
Solution Approach 2:
The patent introduces an intermediary substance (water or oil) that transmits pressure uniformly to the diaphragm. This intermediary allows the single diaphragm to experience the combined effect of pore-water pressure and total earth pressure, enabling accurate effective stress measurement without requiring multiple separate sensing elements.
2Measurement precision
If separate transducers are used for pore-water pressure and total stress, then measurement can be performed, but equipment and installation costs are substantially increased
Solution Approach 1:
The patent merges multiple measurement functions into a single device. By integrating pore-water pressure sensing and total earth pressure sensing into one effective stress cell with a single diaphragm, the invention reduces equipment costs and simplifies installation compared to using separate transducers for each measurement.
Solution Approach 2:
The single diaphragm in the effective stress cell serves multiple functions: it measures both pore-water pressure and total earth pressure simultaneously, and directly determines effective stress. This multi-functionality eliminates the need for multiple specialized transducers, reducing overall system cost and complexity.
3Measurement precision
If two separate transducers are required for pore-water pressure and total stress measurement, then the measurement process can be completed, but the response of the transducers to applied pressure is not identical causing errors
Solution Approach 1:
The patent combines both pressure measurements onto a single diaphragm, ensuring that both pore-water pressure and total earth pressure are sensed by the same sensing element. This eliminates the response inconsistency issues that arise when using separate transducers with different characteristics.
Solution Approach 2:
The water or oil intermediary substance ensures uniform pressure transmission to the diaphragm, creating a consistent and reliable pressure field. This intermediary medium guarantees that the single diaphragm experiences identical pressure conditions from both sources, ensuring consistent and accurate effective stress measurement.
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 approach reduces measurement errors, simplifies the process, and lowers costs by allowing direct and accurate determination of effective stress in saturated soil, providing high accuracy and long-term stability.
Implementation Method 1
the plurality of pores allows the pore-water below the porous diaphragm to enter the interior space for filling the interior space with the pore-water to balance pore-water pressures on the outer surface and the inner surface
Implementation Method 2
the deflection of the sensing diaphragm is only caused by the effective stress such that the effective stress is directly determined by the measured strain change
Data Source
AI summary
The present disclosure provides an effective stress cell for direct measurement of effective stress in saturated soil. The effective stress cell comprises a sensing diaphragm, a porous diaphragm, a connector and a strain sensor. The porous diaphragm allows pore-water to enter the interior space between the sensing diaphragm and the porous diaphragm to provide complete balance of pore-water pressures in the front and back of the sensing diaphragm. Thus, the effective stress cell can directly and accurately measure the effective stress in saturated soil using only one diaphragm at one location without measuring pore-water pressure.