In the field of tunnel construction, support operations serve as the “lifeline” ensuring project safety and stability. They not only resist the pressure from surrounding rock during excavation to prevent collapses but also provide reliable structural support for the tunnel's long-term operation. As tunnel construction advances into deeper and more complex geological zones, traditional support equipment increasingly struggles to meet the demands for efficient and precise construction. Against this backdrop, split-type anchoring drilling rigs have emerged as critical equipment in modern tunnel support engineering,
offering innovative solutions for support operations in complex geological conditions through their unique technological advantages.
I. Technical Principles and Core Characteristics of Split-Type Anchoring Drilling Rigs
(1) Analysis of Working Principles
The split-type anchoring drill adopts a modular design, with its core system comprising four components: the power unit, drill frame structure, drilling assembly, and intelligent control system. The power unit provides drive for the entire machine via hydraulic or electric means. Hydraulic drive is more suitable for high-load operations, delivering stable and robust power output; electric drive offers advantages in environmental friendliness and noise control, making it ideal for tunnel projects with stringent environmental requirements.
The drill frame structure serves as the “skeleton” of the rig, fulfilling dual functions of support and guidance. Its adjustable angle design ensures the drill bit follows the precisely engineered trajectory, effectively preventing borehole deviation. The drilling assembly acts on rock through a combination of rotary cutting and percussive breaking. Depending on geological conditions, different drill bits can be flexibly switched, such as alloy bits for hard rock or auger bits for loose formations.
The intelligent control system serves as the “brain” of the split-type anchoring drill rig. Through integrated sensors and data processing modules, it continuously monitors critical parameters during drilling—including rotational speed, thrust force, and impact frequency—and automatically adjusts settings in response to geological changes. For instance, when encountering fractured rock layers, the system automatically reduces thrust force and modulates impact frequency to prevent borehole wall collapse, ensuring stable drilling operations.
(II) Core Features Highlighting Technical Advantages
Exceptional Geological Adaptability: For common tunnel construction challenges like hard rock, loose sandy soil, fractured rock, and water-rich strata, the split-type anchoring drill rig flexibly employs multiple techniques including conventional down-the-hole hammer drilling, pipe-following drilling, and auger drilling. When traversing fault zones and fractured belts, casing-followed drilling effectively isolates loose surrounding rock by advancing casing synchronously, preventing borehole collapse and ensuring continuous drilling. In water-rich strata, specialized water-resistant drill bit designs minimize groundwater interference with drilling operations.
High-Precision Operation Capability: Leveraging advanced laser guidance and positioning systems, the split-type anchor drilling rig achieves industry-leading drilling accuracy. In actual construction, drilling depth deviation is controlled within ±50mm, with angular deviation not exceeding ±1°, significantly outperforming traditional drilling equipment. This high precision provides an accurate foundation for subsequent anchor rod and cable installation, ensuring tight integration between support structures and surrounding rock and substantially enhancing support stability.
Efficient operation accelerates construction progress: With robust power output and adjustable drilling parameters, the split-type anchor drilling rig maintains high drilling efficiency across diverse geological conditions. In typical rock and soil strata, it achieves drilling speeds of 5-10 meters per hour—5 to 10 times faster than manual drilling and 2 to 3 times faster than basic drilling equipment. For a 2-kilometer tunnel, using the split-type anchoring drill for support operations can shorten the support construction cycle by approximately 30%, providing strong assurance for the overall project's timely completion.
Flexible and Convenient for Tunnel Environments: The split-type structural design allows individual components to be disassembled and transported separately, perfectly adapting to the confined working spaces within tunnels. With lightweight components, it can be easily transported via small-scale tunnel transport tracks or forklifts. Assembly and deployment at the work site can be completed within 1-2 hours. Additionally, the drill features remote control functionality, allowing operators to conduct drilling operations from a control console located 50 meters away from the tunnel face in a safe zone. This significantly reduces personnel exposure time in hazardous areas and lowers construction safety risks.
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II. Diverse Applications of Split-Type Anchor Drilling Machines in Tunnel Support
(1) Bolted Support: The “Stabilizing Line of Defense” for Initial Support
Bolted support serves as the core method for initial tunnel support. By embedding bolts into the surrounding rock, it leverages friction and bond forces between the bolts and rock mass to consolidate loose rock into a cohesive unit, enhancing the rock's inherent stability. During anchor rod support construction, split-type anchoring drills can flexibly adjust drilling parameters based on rock mass classification: For Grade III rock mass, anchor holes requiring 3-4 meters depth are drilled. Using conventional drilling techniques with alloy drill bits, the drill rapidly completes boring operations, achieving an average daily drilling output of 150-200 meters. For Grade IV rock mass, where stability is poor, the rig switches to casing-assisted drilling. This method simultaneously advances casing into the borehole during drilling to prevent wall collapse, ensuring smooth anchor installation.
(II) Cable Support: The “Powerful Bond” for Deep Support
In tunnel sections with severe geological conditions (e.g., Grade IV or V rock mass), anchor bolt support alone is insufficient to meet reinforcement requirements. Cable support must be employed for deep-level reinforcement. Cables typically span 10-20 meters, demanding extremely high precision in drilling depth and verticality. Split-type anchor drilling rigs leverage their robust deep-hole drilling capabilities. By optimizing drill string configurations—such as employing high-strength drill pipes and wear-resistant drill bits—they effortlessly tackle the dual challenges of hard rock and fractured formations. During drilling, the intelligent control system continuously monitors borehole pressure and drilling speed. It automatically adjusts parameters upon encountering rock layer changes, ensuring the drilled hole meets design specifications for depth and verticality. This guarantees precise anchor cable installation and secure anchoring.
(3) Pipe Arch Advance Support: A “Pre-reinforced Barrier” for Adverse Geology
When tunnels traverse shallow cover sections, weak fractured zones, or faults, pipe arch advance support is a critical technology for ensuring excavation safety. Pipe arches typically use steel pipes with diameters of 100-150mm and lengths exceeding 30 meters, which must be pre-installed into the surrounding rock before tunnel excavation to form a “protective canopy.” Separate anchoring drilling rigs equipped with high-precision guidance systems can control drilling straightness error within 0.5%, ensuring pipe arches are precisely installed along the designed trajectory. Simultaneously, the rig's high-torque drilling capability easily accommodates the large-diameter requirements for pipe arch boreholes. Combined with pipe-following drilling techniques, it effectively prevents borehole collapse, providing stable pathways for pipe arch installation. This preemptively reinforces the overlying rock mass, reducing excavation risks.
(IV) Grouting Reinforcement: A “Remedial Approach” to Enhancing Rock Mass Properties
Grouting reinforcement improves rock mass integrity and strength by injecting grout into fractures and voids to fill gaps and cement rock. During grouting operations, the split-type anchoring drill rig can drill grouting holes at specific intervals and angles based on fracture development patterns. For example, in joint-fractured rock zones, the rig employs helical drilling techniques to create grouting holes with diameters of 50-80mm and depths of 5-8 meters, ensuring uniform grout penetration into the surrounding rock. Additionally, the rig can integrate with grouting equipment to perform “drilling-grouting” operations in a single pass, reducing process transition time and boosting grouting reinforcement efficiency.
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III. Project Case Study: Practical Application of Split-Type Anchor Drilling Rigs
A mountainous highway tunnel project spanning 3.5 kilometers traversed complex geological conditions, including interbedded sandstone and shale formations and two fault zones. The surrounding rock primarily classified as Grade IV, with sections reaching Grade V, posing extreme challenges for support construction. The project employed split-type anchoring drilling rigs as core support equipment, implementing tailored construction plans for different geological sections:
In sandstone-shale interbedded zones, where rock hardness was high but stability was good, the rigs utilized conventional down-the-hole hammer drilling techniques with alloy drill bits for anchor bolt and cable borehole operations. During actual operations, the rig achieved an average daily drilling length of 200-300 meters, representing a 40% efficiency increase over the originally planned conventional rigs. Monthly support work mileage exceeded 200 meters.
When traversing fractured fault zones, loose rock masses saturated with groundwater made collapses highly likely during drilling. The project team employed the casing-in-drill technique with the split-type anchoring drill rig, simultaneously installing 127mm diameter casing during drilling to effectively isolate loose rock from groundwater. By dynamically adjusting drilling parameters through the intelligent control system, they successfully resolved the borehole collapse issue, completing a 25-meter-long pipe arch drilling operation and ensuring safe tunnel excavation progress.
Ultimately, the tunnel support construction cycle was shortened by 20% compared to the original plan. Support quality met all design requirements upon inspection, and no safety incidents occurred during construction. This fully validated the reliability and superiority of split-type anchoring drilling rigs in complex geological conditions.
IV. Advantages in Application and Unresolved Challenges
(1) Significant Advantages Driving Project Upgrades
Notable Cost Reduction and Efficiency Gains: The high-efficiency drilling capability substantially shortens the support construction cycle, reducing labor and equipment rental costs. For a 3-kilometer tunnel, using the split-type anchoring drill saves approximately 30% in labor costs and 20% in equipment rental expenses, while avoiding additional costs from schedule delays, resulting in significant overall economic benefits.
Comprehensive Enhancement in Support Quality: High-precision drilling ensures accurate installation of support structures like rock bolts and cables, significantly improving support reliability. Engineering inspection data shows that support structures constructed with split-type anchoring drills exhibit 25%-30% less surrounding rock deformation compared to traditional methods, substantially reducing rework risks and safety hazards.
Enhanced Construction Safety: Remote operation minimizes personnel exposure in hazardous zones. Combined with safety protection systems (e.g., overload protection, emergency shutdown), it effectively prevents accidents like rockfalls and collapses. Project statistics indicate an 80% reduction in construction accidents compared to traditional methods.
(II) Challenges in Practical Application
High equipment investment costs: As high-tech machinery, split-type anchoring drills typically cost 3-5 times more than conventional drills, posing financial pressure for small and medium-sized construction firms with limited capital. However, their high efficiency and low failure rate reduce overall costs in the long term, with equipment payback periods usually spanning 1-2 years.
Stringent maintenance requirements: The complex equipment structure necessitates regular upkeep of core components (e.g., hydraulic systems, intelligent control systems) by specialized technicians. Improper maintenance can trigger equipment failures, disrupting construction schedules. Statistics indicate that non-compliantly maintained equipment experiences over three times the failure rate of properly maintained units.
High technical threshold for operators: Personnel must master equipment principles, drilling techniques, and emergency response skills, requiring systematic training before operation. Currently, the industry faces a relative shortage of professionally qualified operators. In some projects, inadequate operator skills prevent equipment from performing optimally, impacting construction efficiency.
V. Development Trends and Future Outlook
The application value of split-type anchoring drilling rigs in tunnel support engineering has gained widespread industry recognition. With continuous technological iteration and upgrades, future development will focus on the following directions:
In terms of intelligence, integration of AI technology and big data analytics will enable automatic geological condition recognition and intelligent optimization of drilling parameters, further enhancing operational precision and efficiency. In automation, unmanned operation systems will be developed. Through remote control and autonomous navigation technology, “unattended” drilling will be achieved, completely eliminating personnel safety risks; In adaptability, more specialized drilling tools and processes will be developed. Examples include ultra-high-pressure impact drilling tools for extremely hard rock formations and corrosion-resistant equipment for deep-sea tunnels, meeting the construction demands of more complex geological conditions.
In summary, split-type anchoring drilling rigs have become core equipment in modern tunnel support engineering, demonstrating superior performance in enhancing construction efficiency, ensuring project quality, and safeguarding safety.
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V. Development Trends and Future Outlook
The application value of split-type anchoring drilling rigs in tunnel support engineering has gained widespread recognition within the industry. With continuous technological iteration and upgrades, future development will advance in the following directions:
In terms of intelligence, AI technology and big data analytics will be integrated to enable automatic geological condition recognition and intelligent optimization of drilling parameters, further enhancing operational precision and efficiency. In automation, unmanned operation systems will be developed. Through remote control and autonomous navigation technology, “unattended” drilling will be achieved, completely eliminating personnel safety risks; In adaptability, more targeted specialized drilling tools and processes will be developed. Examples include ultra-high-pressure impact drilling tools for extremely hard rock formations and corrosion-resistant equipment for deep-sea tunnels, meeting construction demands in more complex geological conditions.
In summary, split-type anchoring drilling rigs have become core equipment in modern tunnel support engineering, offering irreplaceable advantages in enhancing construction efficiency while ensuring project quality and safety. Although current challenges exist in cost, maintenance, and personnel, these issues will gradually be resolved through technological advancement and industry development. In the future, split-type anchoring drilling rigs will undoubtedly play an even greater role in tunnel construction, providing robust support for the high-quality development of China's transportation infrastructure.
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