Portable Soil Shear Device Using Electromagnetic Loading
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Solution Overview
Problem
Conventional in-situ soil shear strength tests are costly, time-consuming, and limited in applicability, with poor representativeness and large errors in measuring true shear strength, especially for layered soils and varying terrains, and cannot simulate shear strength under overburden loads.
Innovation Solution
A portable soil mass in-situ shear test device with a cylindrical casing, shear core, and ratchet mechanism, utilizing an electromagnetic loading system and ring knife system for precise torque measurement and pressure application, allowing for quick and accurate shear strength testing on various terrains and soil types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional large-scale in-situ shear tests are conducted, then shear strength data can be obtained, but the cost is high, testing period is long, and operation is complicated
Solution Approach 1:
The patent replaces conventional complex mechanical testing systems with a simplified portable device that uses a rotating cutter head to directly cut through soil layers. The shear strength is determined by measuring the torque required to rotate the cutter head, substituting traditional mechanical shear boxes with a rotational cutting mechanism that is faster, cheaper, and equally accurate.
Solution Approach 2:
The patent employs a disposable or easily replaceable cutter head that can be quickly exchanged between tests. This eliminates the need for expensive, complex setup and teardown of large-scale testing equipment, significantly reducing both cost and time while maintaining measurement accuracy through direct soil cutting.
2Measurement precision
If conventional cross-plate shear test is used, then in-situ shear strength can be measured, but there is time difference between side and top surfaces reaching shear failure, resulting in average shear strength rather than true peak value
Solution Approach 1:
The patent uses a cylindrical cutter head with curved cutting edges that rotate to cut through the soil. This rotational cutting action ensures simultaneous engagement with both top and side surfaces of the soil sample, eliminating the time difference in shear failure occurrence and capturing the true peak shear strength rather than an averaged value.
Solution Approach 2:
The cutter head is pre-positioned to engage the soil sample before rotation begins, ensuring that both top and side surfaces are simultaneously prepared for shear failure. This preliminary positioning eliminates the sequential failure timing issue in conventional tests, allowing true peak strength measurement.
3Adaptability or versatility
If conventional in-situ shear test equipment is used, then shear strength under natural stress state can be measured, but the equipment is not portable and cannot be used on various terrains
Solution Approach 1:
The patent divides the testing equipment into modular components: a handheld housing, a detachable cutter head, and a compact torque measurement system. This segmentation makes the equipment portable and adaptable to various terrains including slopes and unstable ground, while maintaining measurement capability through the integrated torque sensor that measures rotational resistance.
4Measurement precision
If indoor soil shear tests are conducted, then controlled testing conditions can be achieved, but sample size is limited and representativeness is poor
Solution Approach 1:
Instead of bringing small soil samples to the lab for testing, the patent inverts the approach by bringing the testing device to the soil in-situ. The portable cutter head cuts directly into the ground, allowing large-volume soil engagement and maintaining natural soil structure, thereby improving sample representativeness while achieving controlled measurement conditions through the standardized torque measurement system.
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 device is cost-effective, easy to operate, and significantly reduces testing time, providing reliable and accurate shear strength data suitable for diverse soil conditions, including layered soils and slopes, with improved precision and applicability.
Implementation Method 1
a cavity at a lower portion of the shear core contains, from bottom to top, a rubber plug, an electromagnet lower piece and an electromagnet upper piece to apply a pressure on a top surface of a test soil core
Data Source
AI summary
A portable soil body in-situ shear test device includes: an active force system arranged externally, a passive shear system and an electromagnetic loading system arranged internally, and a ring knife system arranged at a bottom. Compared with the conventional in-situ soil shear strength test device and test method, the present invention is convenient to install and carry as well as simple to operate, and has strong applicability. The present invention is suitable for layered soils with large cross-plate shear test errors, and for soils with different consolidation degrees at various sites and various terrains. A test method adopting the device can simulate the shear strength of the soil mass under different overburden loads without disturbing the mechanical properties of the in-situ soil mass, which has high promotion value in the test of in-situ soil shear strength.