First, drilling machinery classification  

(1) According to the principle of drilling is divided into: impact rotary type, rotary rolling type, rotary cutting type

(2) According to the original driving power: wind (gas), hydraulic, electric, internal combustion engine, etc.

(3) Divided by engineering use: open air, underground, underwater drilling machinery, etc.

Two, rock drill  

(1) Pneumatic rock drill

Pneumatic rock drill is the most widely used rock drill in China, but its energy utilization rate is low, the drilling speed is slow, loud noise, there is a trend of being replaced by hydraulic rock drill, the most used in the tunnel is air-leg rock drill, the drilling diameter is 32~45mm, the drilling depth is less than 5m, more than 3m drilling speed decline. The working pressure of domestic pneumatic rock drill is about 0.4~0.6MPa. The maximum air consumption is 4.9m3.min-1.

(2) Hydraulic rock drill

Most of the power of foreign hydraulic rock drills is 20kW, the diameter of tunnel drilling is about 33~64mm, the diameter of open-air drilling is larger, in 64~102mm, commonly used in Sweden Atlas Copco, Finland Tamrock, Japan Guhe and other company products are representative.

Air leg drill

(1) The impact drilling tool is called a drill rod: including a drill head, a drill rod, a drill shoulder and a drill tail.

(2) The general drill rod, shoulder and tail are a whole. The section of the drill rod has two kinds of circular and hollow hexagon, and the most used is the hollow hexagon.

(3) The bit head is: cross shape and a font, etc. One of the most used is a font. A shape bit is used to drill solid and ductile rock, compared with other bits, its structure is simple, high chisel speed, so the most widely used, but its disadvantage is difficult to open the hole, crack rock easy to stick the bit, diameter wear faster. The cross-shaped bit can basically overcome the above shortcomings, but compared with a font, the amount of hard alloy sheet is larger, and it is difficult to manufacture. Grinding is more troublesome, robustness and drilling rate are poor.

(4) Air leg pneumatic rock drill is generally used in tunnel construction, and guide rail hydraulic rock drill is used when the truck is drilling.

(5) The weight of air leg pneumatic rock drill is generally less than 30kG, the main engine is installed on the air leg, and the thrust drilling by the air leg can drill horizontal or inclined perforations, such rock drill has YT24, YT26 and YT28. Generally, the most used is YT28, which is mainly composed of the main engine, the air leg and the wind (water) pipeline. Y for rock, T for leg.

Hydraulic rock drill

Domestic manufacturers successfully developed a leg type hydraulic drilling unit, the hydraulic drill will be combined together, powered by mobile hydraulic station, to overcome the air drill noise, high energy consumption defects, make up for the hydraulic drilling rig expensive shortage. Its disadvantage is that it is vulnerable and the failure rate is too high. The following figure is the domestic production of leg type hydraulic drilling unit

Its advantages are: better environmental protection. The noise of hydraulic drill is 10DB-15dB lower than that of manual hand-held air drill; Hydraulic drill also has no exhaust like air drill, there is no fog on the working face, and the air is fresher. At present, hydraulic drilling has been widely used in tunnel engineering.

Hydraulic drilling rig

Drilling rig is the drilling mechanism, propulsion device, positioning device installed on the mechanical chassis or drilling frame for drilling operations. Foreign drilling RIGS are developing in the direction of full automation and intelligence to achieve remote control, unmanned operation or one-person operation of multiple machines. The following is the ATLAS Copco WE3 three-arm full-computer drilling rig produced abroad.

Two TOMRACK Axera T12 three-arm hydraulic drilling RIGS are commonly used in China to excavate the full section of the tunnel, and the cycle time from vehicle placement to ventilation and dust removal is about 315min

It is equipped with 2 three-arm rock drilling trucks for passenger or double-line large-section tunnel drilling, which can be divided into two working groups. The drilling and blasting construction with drilling rig has several advantages:

(1) Less personnel: each shift is equipped with 3 operators per vehicle.

(2) The drilling speed is fast: the drilling time of a single hole of 5 meters deep is 3 to 5 minutes.

(3) High efficiency: the time of single cycle (4.5 meters) of drilling and blasting for full section excavation with a truck can be controlled in 3.5 ~ 4 hours, which can increase the efficiency of drilling and blasting construction by 60 ~ 70% compared with that of multi-functional bench. The full section excavation of the drilling platform reaches 270 m/month.

(4) Multi-use of one machine to improve the quality of bolt construction: the use of drilling rig drilling system bolt hole, improve the construction efficiency of the bolt, effectively control the Angle and depth of the bolt.

(5) Safety and environmental protection: the palm surface does not need a large number of operators and a large number of feng shui pipelines during the drilling process, the use of high-pressure water to follow up the drilling, reducing the rock dust on the palm surface.

Three, air compressor

(1) Classification of air compressors

There are many kinds and forms of air compressors. According to the power source, there are: internal combustion drive, motor drive; According to the lubrication method, there are: oil-free and oil-free; According to the foundation is divided into: fixed and mobile; According to the structure type, there are: rotary type, piston type, diaphragm type and other classification forms. Among them, the piston type and the rotary type of screw, slide type three forms are more common. Slide type is mainly minicomputer.

Piston type air compressor has small power, less power consumption, and easy to adjust the air supply, but the weight of this type of air compressor is large, the overall size is large, and the maintenance workload is large.

Screw compressor has the advantages of simple structure, few parts, compact shape, light weight, less maintenance, no inertia force, small foundation, reliable operation, etc. Its disadvantage is high cost, large noise, and increases with the increase of exhaust volume, and must be used in the city with sound insulation cover or muffler.

(2) Air compressor selection principle

The pressure loss should be considered when the pipeline is long; For a long period of time, the gas is more concentrated should be selected fixed, in order to facilitate maintenance and management, on the contrary, you can use mobile; The operation cost of the electric type is relatively low, and the electric type air compressor should be preferred when the power supply conditions are good. The volume efficiency of piston type decreases more than that of screw type in plateau area. The vertical and horizontal types in piston air compressors have been basically eliminated and should not be used.

(3) Determination of main parameters and working mode of air compressor type selection

Determination of exhaust pressure: The determination of compressor exhaust pressure is more important. The higher the pressure, the more power you use. If the pressure is too low, the pneumatic tool cannot be driven. Generally, the required pressure is the pressure drop caused by pipeline loss plus the use pressure, which is the minimum pressure. The formula for calculating the pressure drop of long distance pipeline conveying compressed gas is as follows:

At present, the working pressure of pneumatic drilling YT28 commonly used in tunnel construction is 0.4 ~ 0.63MPa, the pipe length is 1000m, the inner diameter of the air pipe is 150mm, the absolute pressure is 8bar, and the volume flow is 20m3 / min. The pressure drop △P calculated by the pressure drop formula is 0.03ba r. Therefore, the exhaust pressure of air compressor configured in tunnel construction is appropriate to choose 0.7MPa. Select the air compressor to match the required air displacement, and leave a 20% margin, generally calculated using the following methods.

To determine the total displacement, the usual way is to obtain a larger displacement of the smaller displacement air compressor in parallel, and turn on the machine one by one as the gas consumption increases, which is not only good for the power grid, but also can save energy. In tunnel construction, multiple compressors with a volume flow rate of 20m 3 / min are generally used in parallel. The cooling method of air compressor is divided into water cooling and air cooling, and the water cooling method has four disadvantages: a. Must be equipped with a complete water supply system, the cost is large; b. Waste a lot of water resources; c Water-cooled cooler life is short; d. Use freezable cylinders in cold areas.

With the increase of altitude, the air becomes thinner, the intake pressure of the air compressor is reduced, and the volumetric efficiency is also reduced. In order to ensure the same performance as at sea level, in the equipment selection, the power consumption of the internal combustion engine or motor should be considered, and the compressor should choose a larger volume flow rate. If the correction factor at sea level is 1.0, the correction factor is generally increased by 0.03 for every 300m increase in altitude.

In the construction of tunnel rail transportation, with the extension of the tunnel, the air compressor should also be moved forward, otherwise it will cause great waste because the pipeline loss is too large. The 20m3 / min piston air compressor generally selected for tunnel construction is a fixed machine (the piston electric air compressor larger than 20m3 / min has no mobile machine due to structural reasons). Due to the inconvenience of movement, more high-pressure air pipes need to be invested. Mobile air compressor station is adopted under the premise of good air quality in the tunnel, that is, the air compressor entering scheme. To reduce input and reduce losses.

For the tunnel with trackless transportation construction, the air quality in the tunnel is generally poor. It is recommended to use a fixed air compressor station outside the hole to ensure the quality of air and reduce the wear of the air compressor.

  The purchase price of 20m3 / min piston air compressor is about 90,000 yuan per unit, the mobile screw machine is about 250,000 yuan per unit, and the difference is about 16,000 yuan. Under the same conditions, the depreciation life of the electric compressor is 10 years, and the general consumption of the piston machine is more than that of the screw machine in 10 years: moreover, the maintenance cost of the piston machine is doubled with the increase of service life. Therefore, in terms of cost performance, screw machine is better than piston machine.

The number of air compressors in the air compressor station is generally 3 to 6, and the standby amount should be greater than about 20% of the calculated air supply, but the standby amount should not be less than 1.

For the full section construction of 250km/h high-speed rail tunnel (single hole and double line), about 30 pneumatic rock drills are usually equipped, and 5 to 6 commonly used 20m3/min air compressors are used for wind (1 standby), and a total of about 100m3 air is used for 30 air drills. In actual construction, the average air consumption of each YT28 air drill is 3m3/min, and the total air consumption of 28 air drills is 28*3=84m3/min. The average footage is about 3.5m, the number of holes is about 160, and the drilling time is about 6h.