Rock Sample Integrity via PVC Sleeve and Water Circulation
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Solution Overview
Problem
Current methods fail to obtain representative rock samples with integral fracture networks for laboratory testing, limiting the understanding of physical and mechanical properties of jointed rock masses and the stability assessment of underground caverns.
Innovation Solution
A method involving site selection, drilling with water circulation to form a columnar rock sample, wrapping it with a heated PVC film sleeve, and protecting it with ring protectors and plastic foam to prevent damage and maintain integrity during sampling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional rock sampling methods are used, then sampling process is simple, but the rock sample cannot represent the integral fracture network of jointed rock mass
Solution Approach 1:
The sampling process is divided into distinct stages: drilling with water circulation to form the core sample, applying the PVC sleeve for protection, and subsequent extraction. This segmentation allows each stage to be optimized independently while ensuring the sample represents the integral fracture network.
Solution Approach 2:
A PVC sleeve is introduced as an intermediary protective layer between the rock sample and the external environment during sampling and transport. This intermediary prevents disturbance and damage to the weak structural planes while allowing the sample to be handled safely.
2Productivity
If rock sample is extracted without protection, then sampling is faster, but weak structural planes are disturbed and damaged
Solution Approach 1:
The PVC protective sleeve is applied to the rock sample before extraction and transport. This preliminary protective action prevents disturbance and damage to weak structural planes during subsequent handling, while the entire process remains efficient through pre-planned procedures.
Solution Approach 2:
A flexible PVC sleeve is used to wrap and protect the rock sample. This thin film structure provides adequate protection against mechanical damage and disturbance of weak structural planes while being easy to apply and remove.
3Reliability
If water is not filled during drilling, then drilling process is simpler, but rock sample cannot be kept under hydrostatic pressure state
Solution Approach 1:
Water is circulated during the drilling process to maintain hydrostatic pressure state within the rock sample. This hydraulic approach stabilizes the rock sample by preventing cavity collapse and maintaining in-situ stress conditions, while the water circulation system integrates seamlessly with the drilling operation.
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
Ensures the integrity of rock samples with fracture networks, preventing structural plane separation and allowing reliable evaluation of rock mass properties and cavern stability.
Implementation Method 1
heating a prefabricated transparent cylindrical PVC film sleeve with a wall thickness of 3 mm and an inner diameter slightly less than the outer diameter of the rock sample to make it expand
Implementation Method 2
after the PVC sleeve is cooled it clings tightly to the rock sample and exerts certain pressure on the rock sample
Implementation Method 3
the rock sample may be kept under a hydrostatic pressure state with a hydrostatic head of 1 m
Data Source
AI summary
The present disclosure relates to a method for sampling rock mass, especially jointed rock mass. The present disclosure provides a simple and convenient method for sampling jointed rock mass to prevent the rock sample from being disturbed and damaged during sampling and accordingly resulting in opening of the weak structural planes, to therefore obtain rock specimen correctly reflecting the basic physical and mechanical characteristics of rock mass comprising integral fissure network. The method for sampling jointed rock mass of the present disclosure comprises the following steps: Step a: Siting; Step b: Drilling; Step c: Protecting; and Step d: Sampling. The method is suitable for determining the basic mechanical properties of the rock mass and for assessing the stability of caverns in jointed rock mass.