From foundation inspection of skyscrapers to resource exploration of deep-sea oilfields, core drilling rigs have become an indispensable technical support for the construction, mining and geological industries with their unique dual functions of cylindrical sampling and accurate hole formation.
A core drilling rig is a specialised equipment that uses a cylindrical drill bit to extract columnar samples from materials such as concrete, rock, asphalt and even metal. The principle of operation differs from conventional drilling in that the rotary cutting of the hollow core drilling tool creates a preset hole diameter while keeping the columnar sample (rock core / concrete core, etc.) intact within the drilling tool, enabling simultaneous ‘hole making – sampling’ operations. This technique allows the acquisition of high quality samples without damaging the surrounding structure and meets the dual needs of material analysis and engineering construction.
Technical advantages of core drilling Rig.
Dual efficiency: Sample collection and pipe/cable perforation can be performed in a single drilling, which is more than 30% more efficient than the traditional process.
Structural protection: less than 5mm radius of damage to the surrounding structure during concrete coring, suitable for inspection of existing buildings.
Sample Integrity: The core acquisition rate can reach over 95%, which meets the demand for accurate analysis in geological exploration.
Core Application Scenarios
Construction projects: In large-scale construction projects, the core drilling rig is used for concrete strength testing by drilling cylindrical concrete core samples for compressive strength testing in the laboratory, providing key data for project quality assessment; in the construction of pre-buried holes for pipelines, it can accurately drill holes in accordance with the design requirements to ensure the smooth laying of pipelines for water supply and drainage, gas and other pipelines, and at the same time, reduce the damage to surrounding Mining Exploration: For the construction of metal pipes and gas pipes, we can accurately drill holes that meet the design requirements.
Mining exploration: for metal veins, the core drilling rig collects continuous core samples, allowing geologists to intuitively analyse the direction of the vein, the ore grade and the state of existence, providing a basis for the design of the mining programme; in the exploration of coal seams, it can be used to obtain core samples and determine the gas content of the coal seams, providing an important parameter for the prevention and control of gas in the safe production of coal mines.
Geological engineering: In the face of landslides, the core drilling rig collects geotechnical samples and constructs a landslide stability model by testing the density, shear strength and other mechanical properties of the samples, to predict the risk of landslides, and to provide data support for the formulation of scientific landslide management schemes (such as anti-slip piles, anchor reinforcement, etc.).
Municipal engineering: In urban underground pipeline crossing construction, the core drilling rig adopts non-excavation technology to accurately drill pipeline passages under roads, buildings, etc. to reduce the impact on urban traffic and residents’ life, and efficiently complete the laying and updating of electric power, communication and other pipelines.
Diamond core drills: the heart of precision cutting
Diamond core drills are manufactured using the diamond process, and the concentration of diamond particles is divided into 30#-120# depending on the hardness of the material. When working in C30 concrete, the life span can be more than 500 linear metres, while when facing hard rock such as granite, it is necessary to use hot-pressing sintered diamond drill bits, with cutting line speed controlled at 20-30m/s.
Core tube assembly: the key to sample preservation
Double-layer nested core tube design:
Outer pipe: 42CrMo alloy steel pipe with tensile strength ≥1080MPa to resist drilling torque.
Inner tube: polyurethane lined with anti-abrasion structure, with snap-off device to achieve automatic core interception
Pressure maintaining device: used to maintain formation pressure during gas content determination.
Auxiliary system: to ensure operational stability
The slurry pump adopts a three-plunger reciprocating pump structure, which generates high-pressure pulsating flow through the reciprocating movement of the plunger, and the rated displacement can reach 200-500L/min, which is especially suitable for hard-rock drilling conditions. When working, the high-pressure mud can not only effectively cool the drill bit and prevent the wear of the drill bit due to friction heat, but also carry the rock chips out of the hole quickly, which ensures the cleanliness and drilling efficiency of the hole.
The casing device is made of high-strength alloy steel, with compressive strength ≥60MPa after special heat treatment process, which has excellent anti-squeeze performance. When working in loose strata or high stress areas, the casing forms a support structure by closely adhering to the hole wall, which can effectively prevent the hole wall from collapsing, shrinking and other accidents, and provide a safe and stable working environment for the drilling construction.
The drill pipe system is strictly made of high-strength alloy steel and adopts the design of thickened pipe body. The threaded part adopts a special taper sealing structure, which has been verified by torque test, and the connection strength reaches more than 90% of the body of the drill pipe, ensuring that it can still maintain a reliable connection and effectively reduce the risk of disconnection when drilling in deep holes and high torque operation.
Surface core drilling rigs: the mainstay of land exploration
With vehicle-mounted mobile chassis and hydraulic stepping mechanism, it is suitable for operation in plain and hilly areas. Typical models, such as the XY-4 drilling rig, can reach a maximum drilling depth of 500 m. Equipped with an automatic feeding system, it can achieve constant pressure drilling and increase the core-taking rate by 15%.
Hydraulic Deep Hole Coring Drilling Rig: The best in geological exploration
Equipped with high-power hydraulic pump station, it can realise core drilling at a depth of over 1000m. Representative models, such as CSR-2000, adopts top drive mode, with rope coring technology, the single return footage can reach 30m, which is 4 times higher than the efficiency of traditional drilling rigs.
Portable core drilling rigs: the preferred choice for field operations
The lightweight design of <50kg makes it suitable for unoccupied areas or steep terrain. For example, QD-20 backpack drilling rig is powered by lithium-ion battery, which can complete 20m of concrete coring with a single set of batteries. It comes standard with a quick dismantling structure, which allows a 3-person team to deploy the equipment in 10 minutes.
Diamond coring process: the standard for hard rock drilling
A diamond drill bit is used with a high pressure flushing fluid (water or mud) to cut the rock at 800-1500rpm. For hard rock with >70% quartz content, a drill bit with diamond concentration ≥85% should be used, and the pumping pressure should be increased to more than 3MPa to ensure that the surface finish of the core Ra≤12.5μm.
Rotary drilling method: the first choice for comprehensive exploration
The drill bit is driven to cut through the rotation of the drill pipe, and mud circulation is used to drain the slag at the same time. In overburden exploration, the scraper bit can be used with casing wall protection, and the drilling speed can be up to 1.5m/h; while in bedrock exploration, it is necessary to switch to the diamond bit, with core tube sampling.
Rope coring technology: a revolution in deep hole operation
An advanced process for recovering cores without lifting the drill, based on the principle of lifting the inner tube assembly out of the drill pipe by means of a wire cable. This technology increases the efficiency of deep hole drilling by 60%, and is particularly suitable for exploration operations at depths of up to 500m, where core contamination can be controlled to less than 3%.
Pre-construction preparation system
Equipment Condition Inspection
Drill bit wear test: using a projector to measure the height of the carcass, wear of more than 2mm needs to be replaced.
Motor temperature rise test: no-load operation for 30 minutes, shell temperature ≤ 65 ℃ is normal.
Hydraulic system leakage test: hold pressure 10MPa, pressure drop ≤ 0.5MPa in 10 minutes.
Site safety assessment
Electrical safety: grounding resistance ≤ 4Ω, leakage protection device action time < 0.1s
Structural load-bearing: load on the support surface of the drilling rig ≥ 200kPa, 10mm thick steel plate to be laid.
Environmental monitoring: If the dust concentration is > 2mg/m³, the dust removal system should be activated.
Drilling operation regulations
Opening stage: speed control at 300-500rpm, feeding pressure ≤5kN, forming 100mm pilot hole.
Normal drilling: hard rock rotational speed 800-1200rpm, soft rock 1500-2000rpm, keep the pump volume 80-120L/min.
Core extraction: Slowly lift the inner pipe by using the jammer, lifting speed ≤ 0.5m/s.
Special situation treatment: when encountering jammed drilling, first apply 10-15kN shock force, duration ≤ 30s.
Non-destructive testing in construction engineering
In the inspection of existing buildings, Φ50mm diamond drill bit is used for concrete coring, and with digital image analysis technology, it can achieve:
Presumption error of compressive strength ≤5 per cent
Crack depth detection accuracy up to 0.1mm.
In-situ assessment of the corrosion condition of steel reinforcement.
Mineral Resources Exploration Breakthrough
In precious metal exploration, rope coring technology combined with X-ray fluorescence analysis can achieve:
Ore body boundary delineation error of ≤5m
Grade analysis time shortened from 72 hours to 4 hours.
Reduction of drilling cost by more than 30%.
Expanding application in new energy field
In shale gas development, directional core drilling technology has achieved:
Horizontal section extension length up to 3000m
Completeness rate of reservoir physical parameter collection ≥98%.
Fracturing effect assessment accuracy increased by 20%.
