Shear Test Device for Rock Mass Discontinuities Under Constant Normal Stiffness
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Solution Overview
Problem
Existing shear test machines cannot accurately simulate the constant normal stiffness conditions of rock mass discontinuities, leading to inaccurate classification and support design in underground engineering, as they only apply constant load and neglect the primary rock stress and horizontal pressure.
Innovation Solution
A shear test device and method that includes a base, loading framework, shear and normal loading systems, and a computer control system to maintain constant normal stiffness by adjusting normal pressure based on real-time displacement measurements, and a horizontal loading system to simulate primary rock stress, allowing for accurate simulation of rock mass conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing shear test machines apply constant load boundary condition, then the test can be performed with simple equipment, but the test cannot accurately simulate underground engineering conditions where constant normal stiffness is required
Solution Approach 1:
The patent transforms the static constant load boundary condition into a dynamic constant normal stiffness boundary condition. The normal loading system continuously adjusts the normal load based on real-time normal displacement measurements to maintain constant normal stiffness, allowing the system to adapt to changing test conditions while accurately simulating underground engineering environments.
Solution Approach 2:
The patent implements a feedback control mechanism where the normal displacement monitoring system continuously measures normal displacement, the computer processes this data to calculate required normal load adjustments, and the normal loading system applies the adjusted load. This closed-loop feedback ensures constant normal stiffness is maintained throughout the shear test, significantly improving simulation accuracy.
2Reliability
If existing shear test machines only apply normal stress, then the device structure remains simple, but the test cannot simulate primary rock stress and horizontal pressure conditions
Solution Approach 1:
The patent divides the loading function into three independent loading systems: normal loading system for vertical stress, shear loading system for shear force application, and horizontal loading system for horizontal pressure and primary rock stress. This segmentation allows each system to perform its specific function independently, enabling comprehensive stress state simulation while maintaining clear functional separation and system manageability.
Solution Approach 2:
The patent creates a multi-functional shear test device that can simultaneously apply normal stress, shear force, and horizontal pressure through its three loading systems. This universal device can simulate various underground engineering conditions including different stress states and rock mass conditions, making it applicable to a wide range of geotechnical testing scenarios.
3Measurement precision
If existing shear test machines use constant load boundary, then the equipment operation is simple, but the obtained mechanical parameters differ significantly from actual engineering conditions
Solution Approach 1:
The patent employs a computer-controlled feedback system that automatically adjusts normal load based on real-time normal displacement measurements to maintain constant normal stiffness. This automated feedback control ensures high measurement precision for mechanical parameters while reducing manual operation complexity, as the computer manages the complex control logic and calculations.
Solution Approach 2:
The patent replaces manual mechanical load adjustment with an automated computer-controlled system. The computer calculates the required normal load to maintain constant normal stiffness based on measured normal displacement and applies it through the normal loading system, substituting complex manual mechanical operations with automated computational control.
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 and method enable accurate determination of rock mass mechanical parameters under constant normal stiffness, improving the classification of surrounding rocks and support design, ensuring construction safety and reducing economic costs by simulating actual engineering conditions.
Implementation Method 1
a normal displacement monitoring system (58) for measuring the magnitude of normal displacement of the test piece in real time
Implementation Method 2
constantly adjusting the normal pressure applied by the normal loading system (54) to the test piece according to the principle that the normal stiffness of the test piece is unchanged
Implementation Method 3
a shear loading system (52) for applying a shear force to the test piece
Implementation Method 4
a normal loading system (54) for applying a normal pressure to the test piece
Data Source
AI summary
The present invention relates to a shear test device and test method of rock mass discontinuities under constant normal stiffness condition. The device includes: a base used for placing a test piece; a loading framework fixedly connected with the base; a shear loading system used for applying a shear force to the test piece; a normal loading system used for applying a normal pressure to the test piece; a normal displacement monitoring system used for measuring the magnitude of normal displacement of the test piece in real time; and a computer control system used for receiving the data of the normal displacement of the test piece in real time, and constantly adjusting the normal pressure applied by the normal loading system to the test piece according to the principle that the normal stiffness of the test piece is unchanged.