DTH drilling rig is a submerged hole drilling rig, whose core operating principle is to install a submerged hammer at the bottom of the drilling column, and to achieve rock-breaking drilling through the synergistic action of the three elements of ‘drilling pressure, rotation, and air pressure’. When the column rotates slowly, the hammer is driven by compressed air, and the impact force generated by the reciprocating piston continuously strikes the rock, forming a highly efficient rock-breaking capacity in conjunction with the rotating movement. This technological breakthrough allows the contractor to seamlessly switch from earth drilling to rock drilling scenarios without the need to replace the equipment, simply by adding compressors and hammers, which significantly improves operational efficiency.
In-depth application in the mining industry
In hard rock mining, DTH drilling rigs perform the key tasks of exploration drilling, production drilling and blast hole construction. Its efficient rock-breaking capacity can penetrate hard rock layers such as granite and basalt, provide accurate blasting holes for mineral mining, and significantly improve the efficiency of ore mining. In the exploration of deep ore deposits, the equipment can achieve kilometre-level drilling operations, providing reliable access to sample collection for geological surveys.
Precision work in the quarry
In quarrying operations, DTH drilling rigs are used for drilling blast holes, barren material extraction holes and rock surface shaping. By accurately controlling the angle and depth of drilling holes, regular mining of marble, granite and other stones can be realised, reducing the waste of resources. Its high-frequency impact breaking characteristics can increase the rate of material formation while maintaining the integrity of the rock, which is especially suitable for the mining of high-value stone.
Foundation construction for building projects
In the construction field, DTH drilling rigs are mainly used for foundation drilling, pile construction and slope anchoring. For anchor drilling in deep foundation support of high-rise buildings, the machine can quickly form holes under complex geological conditions such as pebble layer and medium weathered rock layer, providing reliable support for slope stability. It is also commonly used for over-advanced geological prediction drilling in the construction of urban underground tunnels to ensure construction safety.
Technical innovation of water well drilling
DTH drilling rigs have shown significant advantages in water well construction in hard rock areas. While conventional rotary drilling rigs can drill less than 10 metres per day in granite formations, DTH drilling rigs can achieve a drilling efficiency of 50-80 metres per day. The DTH drilling rig can achieve drilling efficiency of 50-80 m/day. Its air recirculation system can effectively deal with the slurry leakage problem in fractured formations and ensure the quality of water wells, which will play a key role in the development of water sources in arid areas.
Geotechnical Investigation
In geotechnical investigation, DTH drilling rig is used to collect in-situ soil samples and rock samples. Equipped with special core drilling bits, it can obtain high-quality rock cores in complex strata, providing accurate geological data for foundation design of high-rise buildings and bridge projects. In seismic zone engineering survey, this equipment can quickly complete deep hole geostress test drilling, which provides the basis for structural seismic design.
Oil and Gas Resources Exploration and Development
The DTH rig is used for pilot hole drilling and reservoir evaluation drilling in unconventional oil and gas exploration such as shale gas and coal bed methane. Its high wind pressure system can penetrate dense rock layers, and together with the slanting technology, it can achieve directional drilling and provide data support for horizontal well trajectory design. It can also be used as auxiliary equipment for sand flushing and blockage relief in oil and gas well workover operations.
Foundation Engineering Inspection
In the quality inspection of foundation treatment, DTH drilling rig is used to construct load test holes and wave velocity test holes. By arranging test holes at different depths, the reinforcing effect of composite foundations such as rubble piles and soil mixing piles can be evaluated. In tunneling projects, it can be used for the construction of geological radar exploration holes to detect geological hazards such as hidden cavities in advance.
Environmental monitoring project
In soil pollution remediation project, DTH drilling rig is used for sampling drilling and grouting holes in polluted sites. Its air drilling technology can avoid the contamination of samples by mud and ensure the accuracy of monitoring data. In landfill impermeable layer testing, it can quickly complete permeability coefficient test holes, providing technical support for environmental pollution prevention.
High-strength steel frame
The frame is made of Q345B low alloy high strength steel welded together, which has the characteristics of high torsional rigidity and impact resistance. The frame structure has been optimised by finite element analysis to ensure the verticality of drilling. The bottom of the machine is equipped with a hydraulic outrigger levelling system as standard, which enables quick levelling on 15° slopes.
Versatile Powertrain
The machine can be equipped with a Cummins QSB7 diesel engine for use in the field without power. The diesel model is equipped with turbocharged intercooling technology and can maintain 80% of its rated power at altitudes above 3000 metres.
High Air Pressure Compression System
Equipped with high-efficiency screw compressor and intelligent frequency conversion control, the air pressure can be adjusted automatically according to the drilling depth to ensure the efficiency of hard rock crushing.
Combined Drill Column System
The drill column consists of high strength drill pipes and specialised percussion drill bits. The drill bit adopts tungsten carbide teeth inlay technology, which has a service life of up to 2000 metres in granite with 70% quartz content. Splined quick couplings are used for the drill pipe connections, reducing the time to unload a single drill pipe to 15 seconds.
Highly efficient down-the-hole hammer assembly
The core component is the down-the-hole hammer, which has a high impact frequency. The internal self-lubricating piston-liner design, with automatic lubrication by oil mist in the compressed air, enables continuous operation for 500 hours without additional maintenance.
Intelligent control system
Equipped with intelligent control system, integrated with real-time monitoring sensors for drilling depth, rotational speed and wind pressure. The operator interface is easy to operate and supports drilling parameter presetting and fault self-diagnosis, with a response time of less than 0.1 second for misoperation protection.
Hydraulic Stabilisation System
Hydraulic telescopic outriggers are arranged at four corners, with a maximum support force of 25 tonnes for a single leg. Equipped with inclination sensor and automatic levelling algorithm, the equipment can be levelled within 30 seconds, ensuring that the drilling deflection rate is ≤0.5%/100m.
Dust collection system
Equipped with pulse dust cleaning system, the filter bag can be cleaned online to ensure continuous and efficient operation in high dust environment such as limestone.
The DTH drilling system adopts the compound rock breaking mode of ‘bottom impact + rotary cutting’. When the compressed air enters the submerged hammer through the drilling column, it pushes the piston to do reciprocating motion, and when the piston goes down, it hits the drill bit to generate impact force, which breaks the rock; meanwhile, the rotary table of drilling rig drives the drilling column to rotate, so that the drill bit cuts the rock to form a ring-shaped free surface. At the same time, the rotating column is driven by the rotary table of drilling rig, so that the drill bit cuts the rock to form an annular free surface. This ‘impact – rotation’ synergy makes the rock crushing efficiency 3-5 times higher than that of traditional rotary drilling.
In terms of the slag removal system, compressed air serves the dual function of power medium and slag removal medium. High-pressure air enters the bottom of the hole from the centre hole of the drilling column and carries the rock chips back along the annular gap between the drill pipe and the hole wall to achieve continuous slag removal. For strata with high water content, it can be switched to ‘air + water mist’ mixed slag removal mode to prevent rock dust from sticking and clogging.
The efficiency of energy transfer is the core advantage of DTH drilling rigs technology. Since the impactor acts directly on the drill bit, the energy transfer loss rate is <15%, much lower than the 30-40% energy loss of traditional top impact drilling rigs. This high transfer efficiency allows the DTH drilling rig to maintain a stable drilling efficiency in holes deeper than 200 metres.
Equipment Adaptability Advantage
With modular interface design and standardised parameter configuration, DTH drilling rigs can be quickly adapted to more than 90% of directional drilling equipment. This high degree of compatibility is not only reflected in the seamless connection between the power system and the hydraulic pipeline, but also includes the protocol interoperability of the electrical control system, which can be plug-and-play with the mainstream brands of directional drilling equipment on the market. At the same time, the reserved expandable interface of the equipment supports the addition of auxiliary modules according to the needs of special working conditions, which ensures that in the laying of different pipe diameters, complex strata traversal and other operational scenarios, the equipment can be quickly completed the combination of debugging and significantly improve the construction efficiency.
Cost Control Advantage
Compared with the traditional process, DTH drilling rig significantly shortens the construction period and reduces the idle equipment and labour cost by virtue of its high efficient rock-breaking capacity and continuous operation; its low wind pressure working mode significantly reduces the energy consumption, and its modular design reduces the frequency of maintenance and the loss of spare parts. As verified by engineering data from many fields, the use of DTH drilling rigs can reduce the comprehensive operating costs by more than 40%, which can achieve significant economic benefits under the premise of guaranteeing the quality of the project.
Environmental Performance Advantage
DTH drilling rig adopts highly efficient air reverse circulation slag discharge technology, which can reduce drilling fluid consumption by 80% compared with traditional rotary drilling rigs. This significant advantage is especially critical when working in water source protection zones: by significantly reducing the use of chemical slurry, it can effectively avoid the risk of heavy metal ions, flocculants and other chemical substances polluting the groundwater and surface water bodies, and at the same time, reduce the pressure on the environment in the transport and disposal of the slurry, which not only meets the needs of the project progress, but also strictly complies with the environmental protection norms of ecologically sensitive areas, and achieves a balance between the project benefits and ecological protection.
Advantage of operation efficiency
Compared with traditional rotary drilling rigs, the drilling efficiency of the DTH drilling rig is three times higher. Take quartzite as an example, which is a typical hard rock with hardness up to 7 on the Mohs scale and density of 2.65-2.75g/cm³, ordinary drilling rigs are prone to fast wear of drill bits and slow progress. However, the DTH drilling rig, with its unique submerged hammer impacting and crushing principle, together with the impact frequency of high frequency impactor, can quickly break the rock into fine particles, and simultaneously discharged the rock debris efficiently through high-pressure wind, thus realising highly efficient drilling and greatly shortening the construction period. Under complex terrain conditions, the hydraulic stabilisation system and intelligent control system of the DTH drilling rig work together to further strengthen its operational stability. The hydraulic telescopic legs at the four corners of the equipment combined with the automatic levelling algorithm can quickly adjust the machine body to the optimal state even when working in rugged mountains or slopes, which reduces the problem of drilling offset caused by equipment shaking from the root, and strongly guarantees the advantage of drilling quality.
Drilling Quality Advantage
Under complex geological conditions, the DTH drilling rig can strictly control the drilling deflection rate to ≤0.3%/100m by virtue of the high-precision guiding system and intelligent deflection correction technology. This index far exceeds the average level of the industry, which can meet the needs of precision engineering such as overrun geological exploration of urban underground tunnels, positioning of bridge pile foundation, and construction of anchor holes for water conservancy projects. Through millimetre-level error calibration, it can effectively avoid construction safety hazards and material loss caused by drilling deviation, and significantly improve project quality and construction efficiency.
Suitable for different geological conditions:the performance requirements for drilling rigs vary significantly. For example, hard rock such as granite requires high impact power, while loose soil is more suitable for low impact and high speed drilling rigs. In addition, the mobility and size limitations of drilling rigs vary in scenarios such as open-pit mining, tunnelling and water well construction.
Drilling Depth Requirements: The drilling depth directly determines the power and stability of the drilling rig. For shallow holes (usually <30 metres), lightweight drilling rigs can be used, which are easy to move flexibly; for deep holes (>50 metres), heavy-duty drilling rigs equipped with strong support systems and high-torque powerheads are required to ensure that the drill bit is accurately positioned and not easily shifted during the drilling process.
Hole size matching: The hole size is closely related to the type of drill bit and the exhaust capacity of the air compressor. For small diameter (≤100mm) drilling, a standard impactor can be used, while for large diameter (>150mm) operations, a custom-made large-size drill bit with a large-displacement screw compressor is required to provide sufficient air pressure to efficiently discharge the rock debris out of the hole.
Selection of equipment integration or separated: the integrated machine (screw compressor integrated with DTH drilling rig) has the advantages of stop-and-go drilling and strong site adaptability, which is suitable for decentralised operations in the field; although the split machine needs extra space to place the air compressor, it can be independently equipped with a high-power air compressor to meet the demand for ultra-deep holes, large hole diameters and other high-load operations, and at the same time, it is easy to maintain and upgrade in the later stage. Only through the systematic evaluation of the above elements can the optimal model be selected to meet the actual working conditions.
What is the essential difference between DTH drilling and traditional rotary drilling?
DTH technology realises ‘bottom impact’, which improves the energy transfer efficiency by more than 2 times; the traditional process is ‘top impact’, which has high energy loss. Measurement data shows that in f=10 sandstone, the energy consumption of DTH drilling rig is 38% lower than rotary drilling rig.
Is the DTH rig suitable for small projects?
Yes. The DTH is the ideal choice for mining, tunnelling and hydropower projects in complex and varied geological conditions, thanks to its high drilling capacity and stable performance. Its unique submerged impactor design can effectively reduce the resistance of rock breakage during deep hole drilling and significantly improve drilling efficiency. In addition, by adapting different sizes of drill bits and rods, the DTH drilling rig can flexibly cope with different hardness and structure of rock strata, ensuring the accuracy and stability of the drilling operation.
How long is the service life of the drill hammer?
Under normal operating conditions, the DTH rig demonstrates excellent durability and stability, with a cumulative drilling capacity of 8,000 to 10,000 metres. This means that in continuous operation, the rig will not need to be shut down frequently for maintenance and will continue to deliver stable performance.
How to achieve environmentally friendly drilling?
Equipped with high-efficiency dust removal device (filtration efficiency ≥99%) and waste water recycling system. A city project adopts the ‘bag filter + water recycling’ scheme, achieving zero dust emission and 100% recycling of water resources, which was commended by the environmental protection department.
To sum up, DTH drilling rig plays an indispensable role in modern engineering construction with its unique operation principle, diversified application fields and excellent technical advantages. Whether it is foundation construction under complex geological conditions or resource exploration that requires high precision and efficiency, DTH drilling rigs have shown strong adaptability and reliability. Through scientific purchase and standardised use, this equipment will continue to provide efficient, environmentally friendly and economical solutions for various projects, and promote the technological innovation and sustainable development of the engineering construction industry.
