Root-Soil Shear Strength Testing With Stratified Directional Sampling
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Solution Overview
Problem
Current methods for determining the shear strength of farmland soil, which includes plant roots, suffer from test errors due to inconsistencies in the shear surface direction, variations in root content and water content across different soil depths, and differences in root distribution within the same layer, leading to inaccurate measurements.
Innovation Solution
A method involving sampling with a ring knife perpendicular to the actual shear surface, stratifying by depth, and performing sampling in multiple directions within annular areas to ensure consistency and account for variations in root-soil properties, using a dihedral angle and annular sampling to reduce test errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sampling is performed with a ring knife perpendicular to the ground surface using current methods, then the sampling process is simple and quick, but the test error increases due to inconsistency between the test shear surface direction and the actual shear surface direction during tillage
Solution Approach 1:
The sampling process is segmented into multiple directional samples (at least three different directions) taken along the actual shear surface. Each directional sample captures the anisotropic characteristics of the root-soil composite from different orientations, and the results are integrated to obtain a comprehensive measurement that reduces directional bias and improves accuracy while maintaining operational efficiency.
2Productivity
If sampling is performed without stratification, then the sampling operation is simpler and faster, but test error occurs due to differences in root content, water content, and shear characteristics across different soil depths
Solution Approach 1:
The soil profile is segmented into multiple depth layers based on the actual shear depth range. Sampling is performed stratified by depth, with each layer sampled separately to capture the vertical variations in root content, water content, and shear characteristics. This layered approach ensures that depth-dependent property variations are accounted for, improving measurement accuracy while maintaining operational efficiency through systematic sampling procedures.
3Device complexity
If sampling is performed in a single direction, then the sampling process is simpler and requires fewer operations, but test error is introduced due to variations in root structure and distribution in different directions within the same soil layer
Solution Approach 1:
The sampling operation is segmented into multiple directional components (at least three different directions) within the same soil layer. Each directional sample captures the root structure and distribution characteristics specific to that orientation. By integrating results from multiple directions, the method accounts for the anisotropic nature of root-soil composites and reduces the impact of directional root distribution variations, thereby improving measurement accuracy without requiring overly complex equipment.
4Productivity
If the ring knife diameter is increased to reduce the number of samples needed, then the sampling operation becomes faster and less complex, but the ability to capture fine-scale root distribution and depth variations is reduced
Solution Approach 1:
Rather than relying on a single large-sample approach, the method segments the sampling into multiple smaller samples taken systematically in different directions and depth layers. This segmented sampling strategy uses a ring knife with appropriate diameter to capture fine-scale root distribution characteristics while maintaining a manageable number of sampling operations through efficient spatial arrangement and systematic sampling design.
Data Source
AI summary
The present disclosure discloses a test method for reducing test error in shear strength of a root-soil composite, belonging to the field of agricultural engineering testing methods. The method includes: sampling with a ring knife perpendicular to an actual shear surface to ensure consistency between a direction of the actual shear surface of the root-soil composite and a shear surface direction in a direct shear test; determining a shear strength of soil in each layer within an actual shear depth range by stratifying with a minimum thickness of the ring knife; and planning an annular sampling area and performing sampling in various directions along the annular area, thereby reducing test error in determining shear characteristics of the root-soil composite from three aspects.