GB/T 51288-2018 in English
VALIDCode for construction and acceptance of inclined shaft freezing at a mine
- Issued on:2018-05-14
- Implemented on:2018-12-01
- File Format:PDF
- Delivery:Via email within 5 business days
$641.00
Introduction
Standard Background and Scope of Application
This standard is compiled by the China Coal Construction Association and is aimed at the quality control of the entire freezing method construction process for mine inclined shaft projects with alluvial layer thickness ≤200m. It focuses on solving technical problems such as unstable stratum reinforcement and groundwater isolation, and is applicable to inclined shaft projects with vertical freezing holes.
Core term analysis
| Term | Definition | Technical parameters |
|---|---|---|
| Frozen wall | The frozen soil continuum formed around the wellbore | Thickness 2.0-6.5m, average temperature -6~-15℃ |
| Hydrological observation hole | Vertical borehole for monitoring changes in aquifers | Skew rate ≤5‰, flower pipe section needs to be wrapped with filter screen |
| Refrigeration station | Core facility for providing low-temperature brine | Ammonia purity ≥99.8%, brine temperature difference 3-8℃ |
Key technical indicators
Frozen wall design parameters
Graded control according to alluvial layer thickness:
- Top plate thickness: ≥5.0m below 100m, ≥6.0m at 200m
- Average temperature: -8~-15℃ (increasing with depth)
- Cross-circle judgment: water seepage from the hydrological hole continues for 5-7d, and the temperature observation hole has a turning point of -2℃
Refrigeration system configuration
Calculation formula for cooling requirement: Q=πD·L·q·η (η is 1.2-1.35)
Grading control of brine temperature:
- 100m alluvial layer: -23~-25℃
- 200m alluvial layer: -29~-32℃
Key points of construction quality control
- Drilling construction: alluvial layer slope ≤3‰, final hole spacing ≤3.0m
- Freezing pipe installation: No. 20 low carbon steel, wall thickness ≥5mm, test pressure 5MPa/30min
- Refrigeration station acceptance: high pressure section test pressure 1.8MPa, vacuum degree ≥0.097MPa
- Green construction: mud recycling rate ≥ 90%, ammonia concentration ≤ 30mg/m³
Typical problem solutions
Emergency treatment of frozen pipe rupture
Immediately stop brine circulation → drain residual brine → locate the rupture point → cut off the part invading the wellbore → seal the pipe end → grouting and filling
Hydrological hole no water treatment process
Review temperature measurement data → check freezer flow → analyze formation conditions → add holes when necessary → postpone excavation decision
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