Mine Roof Cable Bolt Grout Distribution Conduit
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Solution Overview
Problem
Existing mine roof bolt systems face challenges in distributing viscous liquid grout uniformly, as fast-setting grouts can block flow and lateral cracks divert pressurized grout away from the upper column, leaving gaps between the grouted column and the anchored wedge portion.
Innovation Solution
A cable bolt apparatus with a mechanical anchor, a flexible multi-stranded cable, and a conduit with mixing elements and discharge holes to ensure controlled distribution and mixing of grout within the bore hole, maintaining grout inside the hole until it solidifies and bonds with the rock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If fast-setting grout is used to ensure rapid hardening and support, then setting speed is improved, but grout flow is blocked quickly after injection
Solution Approach 1:
The grout distribution system is segmented into multiple discharge holes along the conduit, allowing grout to be delivered in controlled portions to different locations in the bore hole. This prevents localized blocking while maintaining overall flow continuity and ensures uniform distribution throughout the grout's setting process.
Solution Approach 2:
The conduit is pre-positioned within the bore hole before grout injection, establishing a predetermined distribution pathway. This preliminary arrangement ensures that grout flows along the intended path to all necessary locations before setting begins, preventing flow blockage and ensuring complete penetration.
2Quantity of substance
If pressure is applied to pump grout into the bore hole to ensure complete filling, then grout penetration is improved, but grout is diverted away from the upper column through lateral cracks
Solution Approach 1:
The conduit acts as an intermediary element that directs grout flow from the injection point to specific discharge locations along the bore hole. This intermediary structure prevents grout from being diverted laterally through cracks by providing a controlled pathway, ensuring uniform distribution throughout the upper column while maintaining penetration depth.
Solution Approach 2:
The conduit provides localized grout delivery at specific positions along the bore hole, with discharge holes positioned to target areas that would otherwise be missed. This local quality approach ensures precise grout placement in the upper column and at critical interfaces, preventing both insufficient penetration and lateral diversion.
3Ease of operation
If grout is pumped externally in a separate step after cable installation, then installation simplicity is improved, but grout distribution control is reduced
Solution Approach 1:
The cable installation and grout injection operations are merged into a single integrated process. The conduit is installed with the cable, and grout is pumped through the conduit in the same operational sequence, allowing simultaneous achievement of cable positioning and grout distribution control. This eliminates the need for separate external pumping while maintaining precise distribution.
Solution Approach 2:
The conduit serves multiple functions: it acts as a structural component of the cable assembly, provides a grout distribution pathway, and enables controlled grout delivery. This multi-functionality eliminates the need for separate external pumping equipment while maintaining precise grout distribution control throughout the bore hole.
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 solution ensures uniform distribution and penetration of grout throughout the vertical column, enhancing the stability and support of the mine roof by preventing gaps between the grouted column and the anchored wedge portion.
Implementation Method 1
At least one mixing element is configured to mix the liquid grout material within the bore hole
Implementation Method 2
A seal portion is disposed around the cable segment within the bore hole
Implementation Method 3
the conduit provides a predetermined distribution of the liquid grout material in the bore hole and the seal maintains the liquid grout material within the bore hole while the grout material solidifies and bonds with the rock material
Implementation Method 4
The mechanical anchor is expandable to fix the cable bolt in place in the bore hole
Data Source
AI summary
A cable bolt includes a multi-strand cable segment constructed from steel wire strands, and a drive head. A compressible porous backer rod is placed along cable segment adjacent the drive head. A tubing portion provides a conduit for liquid grout injected under pressure into the bore hole. Tubing portion includes discharge holes that may be predrilled through the wall of the tubing portion. The holes provide a predetermined distribution path for the liquefied grout that is injected into the bore hole. Discharge holes may be evenly dispersed longitudinally along the wall, or distributed to provide a desired, unequal distribution of grout. Distribution holes may be larger at the top of the tubing, or may be distributed adjacent to the top of tubing portion to allow greater cross-sectional flow of grout from the tubing to compensate for factors that restrict grout flow nearer the top.