Multi-hazard fiber sensing and rescue-support localization in underground coal mines

Project background: from isolated alarms to continuous risk assessment

Multi-hazard fiber sensing and rescue-support localization in underground coal mines addresses the long-term safety and condition management of main roadways, production areas, conveyors, goafs, cables, ventilation doors, refuge chambers and critical working faces. Such assets commonly span multiple spaces, process sections or asset identifiers; risks can move along routes, equipment boundaries and structural weaknesses rather than appearing at predetermined measuring points. Key concerns include fire, spontaneous combustion, surrounding-rock deformation, blasting vibration, mechanical faults, distress tapping and impaired communications after incidents. Point sensors, manual inspections and video provide local evidence but may not capture the complete development of an anomaly from onset to response.

The solution uses DTS, DAS, BOTDA/BOTDR and silicon photonic sensors, placing sensing fiber along the paths that need observation to create continuous, localized and replayable records. Its objective is to combine temperature, acoustic/vibration and strain data within one distance-coordinate system to support routine mine safety and post-incident rescue, rather than add isolated equipment. Start design with an asset-risk inventory and verifiable monitoring objectives, then specify range, spatial resolution, sampling, sensing-cable construction, software interfaces and alarms.

Risk progression and monitoring boundaries

For main roadways, production areas, conveyors, goafs, cables, ventilation doors, refuge chambers and critical working faces, distinguish initiating factors, early signs, developing conditions and consequences. Risks including fire, spontaneous combustion, surrounding-rock deformation, blasting vibration, mechanical faults, distress tapping and impaired communications after incidents may occur independently or arise from combined load, environmental, construction and maintenance effects. Capture measurable changes in temperature, acoustics, vibration, strain or local condition and associate them with specific assets and distances.

Sensing principles and technology selection

An integrated solution places continuous DTS temperature, dynamic DAS acoustics/vibration, slow BOTDA/BOTDR strain and sensitive FBG or silicon photonic point measurements in one spatial coordinate system. Different mechanisms provide complementary evidence: temperature indicates thermal anomalies; acoustics/vibration describes event timing and dynamics; strain reveals cumulative structural change; and point sensors add local equipment condition.

The recommended combination is DTS, DAS, BOTDA/BOTDR and silicon photonic sensors. Check monitoring distance, spatial resolution, localization accuracy, channel count, dynamic range, sampling cycle, operating temperature and communications together. Specifications should support the objective to combine temperature, acoustic/vibration and strain data within one distance-coordinate system to support routine mine safety and post-incident rescue, rather than be compared individually. For long routes, prioritize signal-to-noise ratio, reliable localization and far-end stability; for localized high-risk areas, assess coupling, effective sensing length and response time.

System architecture: sensing, interrogation, software and response

The system comprises sensing cable or fiber sensors, splicing and protection units, interrogation equipment for DTS, DAS, BOTDA/BOTDR and silicon photonic sensors, edge processing, application software and supervisory interfaces. Returned signals undergo quality checks, distance calibration and parameter calculation before mapping to asset records. Outputs include live curves, time-space plots, event lists, risk zones, historical trends and reports, rather than an unexplained waveform.

Integrate mine safety, personnel location, public address, dispatch and emergency-command systems, with map locations and graded response. Define the data dictionary, time synchronization, alarm acknowledgment, offline buffering and recovery upload. For important projects, use tiered retention of raw or feature data to support incident reviews, algorithm improvement and threshold changes.

Sensing cable and field installation

Recommended installation: deploy temperature and vibration cable by roadway network and channel; add strain cable to critical structures and build controlled tapping-event models for refuge and rescue areas. Installation quality directly affects results; the same interrogator can respond differently with different mounting, jacket materials and coupling. Design documents should identify start/end distances, slack loops, splice boxes, zone boundaries, fastening intervals, bend radius, pulling tension and protection.

Data analysis and graded alarms

Instead of simply connecting several interrogators, establish unified distance coordinates, asset identifiers and timestamps. Validate data quality within each parameter before cross-checking between parameters. For example, coincident acoustic/vibration and temperature anomalies may increase risk priority; a short impact without subsequent temperature or strain change can enter observation or manual verification.

Initial application criteria: classify events against shifts, equipment operation and known blasting times, retaining waveforms and trends before, during and after incidents. Use advisory, early-warning, alarm and emergency levels, each with defined confirmation times, verification and actions. Calibrate thresholds against actual conditions during trial operation and record every revision, reason and effective date. Display position, asset name, measured value, baseline deviation, duration and supporting evidence together.

Commissioning, acceptance and performance verification

Integrated acceptance must verify each sensing chain and test clock synchronization, distance mapping, asset identifiers and response logic across systems. Simulated events should cover individual and simultaneous multi-parameter anomalies, communication loss and sensing-cable faults, confirming clear indications during degraded operation.

Maintenance and sustained effectiveness

Maintenance assessment should cover valid-alarm rates, confirmation time, false-alarm causes, missed-event reviews, closed work orders and detected trends, not just equipment uptime. Continued labeling of real events can improve recognition models and sustain practical performance after commissioning.

Integration with existing systems

Integrate mine safety, personnel location, public address, dispatch and emergency-command systems, with map locations and graded response. Let the fiber platform handle interrogation, curve analysis and original evidence, while the supervisory system manages consolidated displays, duty workflows and work orders. Depending on the project, interfaces may use Modbus TCP, OPC UA, IEC protocols, REST APIs, message queues or dry contacts. Avoid transferring only an unexplained aggregate alarm.

Every alarm on a map, plan or process diagram should link back to original curves and historical trends. Feed dispositions from supervisory systems back into event records, closing the loop between monitoring, confirmation, response, review and threshold improvement.

Benefits, operating conditions and technical boundaries

The solution replaces sampled inspections of main roadways, production areas, conveyors, goafs, cables, ventilation doors, refuge chambers and critical working faces with continuous observation, retaining traceable early indications of fire, spontaneous combustion, surrounding-rock deformation, blasting vibration, mechanical faults, distress tapping and impaired communications after incidents. Passive fiber, electromagnetic immunity and multiple sensing locations on one fiber can reduce distributed power and maintenance requirements on long routes, at unattended sites or in hazardous environments. Locations and trends help teams narrow inspections, plan condition-based maintenance and prioritize risk.

Equipment selection and detailed design

Begin with five questions: which parts of main roadways, production areas, conveyors, goafs, cables, ventilation doors, refuge chambers and critical working faces require protection; which indications of fire, spontaneous combustion, surrounding-rock deformation, blasting vibration, mechanical faults, distress tapping and impaired communications after incidents must be detected; what localization, response and sampling performance is needed; what routing, power, communications and cabinet facilities are available; and who confirms alarms and owns the response workflow?

Then specify the combination of DTS, DAS, BOTDA/BOTDR and silicon photonic sensors, cable construction, single- or double-ended optical paths, channel redundancy, software licensing and interfaces. For phased projects, reserve fiber, rack space, network addresses and platform capacity. For long-distance or multisite projects, evaluate centralized interrogation, distributed edge nodes and remote maintenance together.

Application-specific validation and limitations

Acoustic and vibration sensing in rescue operations provides supplementary clues. Detection of tapping depends on distance to the cable, propagation through surrounding rock and background noise. It cannot guarantee direct, continuous or precise localization of every trapped person and does not replace existing mine personnel-location or communications systems.

During routine commissioning, conduct controlled tapping at known positions under approved conditions and record observable coverage and signal patterns. If an incident damages the sensing line, clearly identify remaining effective sections rather than displaying old data from failed channels. Assess events alongside personnel records, working-face locations, ventilation and rescue information, retaining raw waveforms for specialist review.

Installation, optical-path calibration and acceptance checklist

Related products and technical resources

Explore the product categories below according to distance, spatial resolution, channels, response and site conditions. Published specifications support preliminary selection; final configuration must account for optical loss, installation and acceptance objectives.