A reef blasting vessel is a special engineering ship for underwater drilling and blasting integrating positioning, drilling, charging, network connection, initiation and safety protection. As the core equipment for waterway dredging, port construction, underwater foundation trench excavation and cross-river pipeline trench construction, it can realize efficient, safe and accurate underwater rock removal in complex waters such as coastal areas, inland rivers, deep water and rapid currents.
1. Introduction to Reef Blasting Vessels
Also known as drilling and blasting working vessels, reef blasting vessels take floating boxes, self-elevating platforms or modular boxes as carriers, equipped with high-pressure air DTH drills, RTK-DGPS high-precision positioning systems, air compressors, power generation equipment, mooring/hydraulic pile positioning systems and special blasting equipment warehouses. All operations are completed on water without manual underwater work.
Note: Real-time kinematic (RTK) is a high-precision positioning technology based on Global Navigation Satellite System (GNSS), which achieves centimeter-level real-time positioning through carrier phase difference observation between base stations and rover stations.
Classification:
Large coastal reef blasting vessels (wave-resistant, multi-drills, deep-water operation),
small inland river reef blasting vessels (compact and flexible, detachable for land transportation),
self-elevating reef blasting vessels (hydraulic pile jacking, current-resistant and stable).
Core configuration: 4–10 DTH drills, six-anchor/hydraulic pile combined positioning, satellite positioning system, waterproof blasting system, vibration and shock wave monitoring equipment.
2. Core Construction Principles
With underwater drilling and blasting as the core process, it follows the whole-process closed-loop operation of accurate positioning → casing drilling → hole inspection and charging → millisecond blasting network connection → safe initiation → slag removal and forming:
Accurate positioning: Adopt RTK-DGPS positioning, fix the vessel position by mooring or hydraulic piles, with positioning deviation ≤40cm, and carry out drilling row by row.
Casing drilling: DTH drills rotate and impact to form holes in casings; double casings are used in quicksand/overburden layers to prevent hole collapse and silting, ensuring accurate hole depth and hole bottom elevation.
Hole inspection and charging: Check hole depth with special hole inspectors, lower waterproof emulsion explosives and non-electric millisecond detonators along casings; no stemming required for deep water, and stemming according to specifications for shallow water.
Millisecond initiation: Adopt series-parallel/hole-by-hole millisecond initiation network, control single-section simultaneous charging to reduce vibration and shock waves; move the vessel to a safe area 150m away for initiation.
Slag removal and forming: Remove slag by grab/cutter suction vessels after blasting to meet the design requirements of water depth, foundation trench bottom width and slope precision.
3. Technical Characteristics and Application Scenarios
(1) Core Characteristics
Accurate and controllable: Precise control of hole position, hole depth and charging capacity, suitable for high-precision foundation trench excavation with flat bottom and straight slope.
Safe and efficient: All on-water operations without high-risk underwater work; waterproof and water-resistant explosives and anti-stray current detonators with low misfire rate.
Strong adaptability: Operable under working conditions of water depth 3–50m and flow velocity ≤5m/s; modular vessels can be disassembled and transported inland without affecting navigation.
Green and environmentally friendly: Basically no flying rocks in deep-water operation; bubble curtain and sectional charging control can greatly attenuate shock waves and vibrations to protect surrounding structures.
(2) Main Applications
Waterway dredging: Remove submerged rocks, widen and deepen waterways, and eliminate rapid rapids.
Port and wharf: Blasting and leveling of rocks in foundation trenches, berthing areas and turning basins.
Hydraulic foundation trenches: High-precision blasting excavation of immersed tube tunnels and cross-river pipeline trenches.
Emergency rescue: Emergency removal of landslide-blocked rivers and navigation-obstructing rocks.
Inland rivers and lakes: Small modular vessels solve construction problems in restricted waters.
Reef driling and blasting vessel:
4. Typical Construction Cases
Case 1: Underwater Reef Blasting Project of Pentium Wharf in Qinzhou Port, Guangxi (2025)
Project Overview
The project is located in Jingujiang Operation Area, Jingu Port Area, Qinzhou Port, with a reef blasting area of about 15,000 ㎡ and an average rock thickness of 3.5m. It is adjacent to Hengrong Wharf, Guanggang Wharf and Jingujiang Bridge, and the blasting area is only 275m away from the planned waterway boundary line, with sensitive surrounding environment and extremely high vibration control requirements.
Core Technologies and Construction Details
Positioning technology: Adopt RTK-DGPS global satellite positioning system to calibrate the vessel position in real time, with dynamic positioning error of reef blasting vessel ≤30cm, ensuring accurate placement of drilling holes at design coordinates.
Blasting equipment: Select electronic digital detonator initiation network with millisecond-level delay accuracy, lightning and stray current resistance, greatly reducing misfire risk.
Initiation process: Apply hole-by-hole millisecond blasting with independent delay for each hole to avoid shock wave superposition, and single-section simultaneous charging is strictly controlled ≤50kg.
Safety monitoring: Synchronously enable blasting vibration monitor to transmit vibration data in real time 24 hours a day, forming a whole-chain safety control closed loop of "positioning-initiation-vibration control-monitoring".
Vessel equipment: Put into use "Haihaizuan 16" reef blasting vessel equipped with multiple high-pressure air DTH drills, casing follow-up drilling to prevent silt hole collapse.
Implementation Effect
The reef group was accurately removed, and the wharf foundation trench passed the acceptance at one time. The blasting vibration was controlled within the specification limit, without any impact on surrounding wharves and bridges, clearing obstacles for the navigation and berthing of the wharf.
Case 2: Reef Blasting Project of Dahaozhou Waterway in Huangpu Port
Project Overview
In the "Dashi-Ershi" water area at the throat of Huangpu Port waterway, the reef distribution area is 28,000 ㎡, which seriously obstructs navigation and caused 135 maritime accidents from 1953 to 1968. The project lasted 4 years, blasted and removed 496,000 m³ of reefs, dredged 330,000 m³, widened and deepened the waterway to 10m and 80m, creating the "Huangpu Underwater Blasting Method".
Core Technologies and Construction Details
Drilling process: Pioneered double-casing automatic adjustment drilling technology, with outer casing diameter 127mm and inner casing 108mm, which can expand and contract with tides to resist interference from water flow, quicksand and hole silting.
Construction mode: Construction without port closure or navigation interruption, all drilling, charging, network connection and initiation were completed on drilling and blasting vessels converted from 220t barges, completely eliminating underwater operations.
Blasting technology: Adopt underwater directional casting blasting, first excavate directional troughs as slag collection pits to form favorable free surfaces, the charging capacity is increased by 40% compared with onshore directional blasting, and the blasted slag is concentrated and accumulated for easy dredging.
Hole network parameters: Drilling diameter 96mm, hole spacing 2.5m, row spacing 2.0–2.5m, over-drilling 0.5–1.5m, unit consumption 0.4–0.65kg/m³, reaching design elevation by one blasting without secondary crushing.
Implementation Effect
Completely solved the waterway bottleneck, reduced the average annual maritime accidents from 9 to 0, saved 10 million yuan in project investment, and formed the first generation of standardized underwater reef blasting construction technology in China.
Case 3: Underwater Trench Project of Cross-River Pipeline in Jialing River, Langzhong (2021)
Project Overview
The Langzhong drinking water intake renovation and expansion project requires a 360m cross-river pipeline to cross the Jialing River. The excavation depth of the rock section trench is 5m, and the normal water depth is about 6m. The project has a construction period of only 30 days, navigation interruption is prohibited, large ships cannot enter the restricted inland water area, and traditional cofferdams/steel platforms have high cost and long construction period.
Core Technologies and Construction Details
Vessel innovation: Develop small assembled reef blasting vessels with box structure detachable for land transportation and rapid on-site assembly, suitable for the "small, fast and flexible" construction needs of inland rivers.
Positioning system: Adopt flexible anchor + semi-jacking hydraulic pile combined positioning, four-corner windlass anchoring + middle lifting pile to stabilize the vessel and maintain hull stability under water flow.
Construction process: Layered step excavation, horizontal striping, longitudinal segmentation, casing follow-up drilling + pipe pulling device without mutual interference, underwater drilling and blasting to form the trench in one time.
Benefit comparison: The transportation and installation period is only 13 days, and the operation platform cost is 529,000 yuan, which is lower than that of cofferdam (1.2 million yuan) and leased reef blasting vessel (600,000 yuan), without affecting navigation and zero pollution.
Implementation Effect
The rock section trench blasting was completed on schedule, awarded as Sichuan Provincial Construction Method, and authorized 2 patents, becoming a benchmark solution for underwater trench excavation in restricted inland water areas.
Case 4: Reef Blasting Project for Jipazi Landslide Rapid Flow in the Three Gorges of the Yangtze River
Project Overview
In the 1982 Jipazi landslide, 230,000 m³ of earth and rock poured into the Yangtze River. During the dry season, the riverbed water-crossing area was blocked by 80%–85%, with a flow velocity of 4–6m/s, forming an extremely dangerous rapids, on the verge of navigation interruption, requiring emergency reef blasting and clearance.
Core Technologies and Construction Details
Construction process combination: First use underwater exposed blasting to blast the flow-protruding mouth and widen the emergency waterway; then use underwater drilling and blasting for complete clearance, suitable for extreme working conditions with flow velocity of 3–5m/s.
Vessel equipment: Customized 300t-class drilling working vessel with high-power anchor cable winches at the bow and stern to resist rapid current; equipped with CQ-150 rapid current resistant DTH drill, double casing drilling, hole diameter 100–110mm.
Charge package technology: Single charge package weight of 20–25kg for exposed blasting, series connected charge packages with spacing of 1.0–1.2m, weight of falling stone 4 times that of charge package to ensure the charge package close to the reef.
Initiation innovation: Test and apply ultrasonic remote control initiation technology to reduce misfires caused by cable breakage by rapid current; dry battery initiator controlled on the positioning vessel, safe and reliable.
Safety control: Maximum single charge for drilling and blasting ≤1200kg, exposed blasting ≤400kg, blasting vibration controlled within 0.8cm/s.
Implementation Effect
Completed 110,000 m³ of reef blasting, restored navigation of the Yangtze River, conquered the world-class problem of underwater reef blasting in deep water and rapid current (flow velocity 6m/s), and the relevant equipment was subsequently used for slag removal in the Three Gorges Project.
Case 5: Underwater Foundation Trench Blasting Project of Dalian Bay Subsea Tunnel (2023–2025)
Project Overview
The foundation trench of the immersed tube section of Dalian Bay Subsea Tunnel has strict requirements for slope gradient and floor flatness precision. All 15 pipe section foundations passed the acceptance at one time, making it a model project of high-precision blasting for coastal underwater rock foundation trenches in China.
Core Technologies and Construction Details
High-precision control: Adopt the high-precision blasting excavation method for coastal underwater rock foundation trenches, strictly control the drilling plane deviation ≤5cm and elevation deviation ≤10cm.
Charging structure: Combine continuous charging and layered charging, stemming section ≥0.6m, accurately control the blasting crushing range to ensure the foundation trench slope forming and floor flatness.
Initiation network: Non-electric millisecond differential series-parallel network, delayed row by row to reduce blasting vibration and avoid surrounding rock disturbance of the foundation trench.
Quality acceptance: All 15 pipe section foundation trenches passed the acceptance at one time, meeting the millimeter-level precision requirements for immersed tube installation.
Implementation Effect
The technology was appraised as domestic leading level by China Water Transportation Association, providing a standardized solution for high-precision construction of subsea immersed tube tunnel underwater foundation trenches.
Reef blasting vessel:
5. Summary
Reef blasting vessels have developed from traditional simple drilling and blasting equipment into modern core equipment for underwater engineering with precise positioning, intelligent technology, safety and environmental protection, and adaptability to diverse waters. From inland river pipelines to cross-sea tunnels, from conventional dredging to emergency rescue, reef blasting vessels continuously promote the upgrading of underwater blasting towards high efficiency, precision, green and safety, making them indispensable key equipment for China's water transportation and underwater engineering construction.
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