The development of drilling and blasting

Nowadays, under different geological conditions, construction period and quality requirements, tunnel construction methods are also diverse. With the development of the country and the maturity of technology, various construction methods have also been developed rapidly. Among them, the new Austrian method can adapt to various geological conditions and solve multiple difficult problems. It has almost become a basic method for building tunnels in weak and broken surrounding rock today. However, in tunnels constructed by the New Austrian Tunneling Method, the excavation method is generally drilling and blasting. From the early days of manually drilling holes with drill rods and hammering, and using detonators to detonate individual charges one by one, to the rise of mechanized drilling and blasting, drilling and blasting has become the main method of tunnel excavation.

The drilling and blasting method is to design a hole in the face of the face, then charge and blast, and then transport the broken stone away, through the steps of spray anchor support, waterproof and drainage, secondary lining, etc., it is built into a passable tunnel. Because of its strong adaptability and high efficiency, the drilling and blasting method has become the main method of mountain highway tunnel construction and excavation. The traditional blasting method generally uses manual drilling, that is, the staff holds a pneumatic drill and is equipped with a simple excavation trolley for drilling and blasting construction. However, manual operations have problems such as harsh environments, uncertain working hours, and high risks. With the development of technology and the improvement of the level of mechanization, new equipment and new methods continue to appear. The improvement and perfection of these technologies not only accelerate the speed of construction, but also significantly improve the quality and safety of construction. In some developed regions, mechanization has basically been achieved. In this regard, there is still some gap between China and other developed countries. Most of the domestic methods are still manual operations, but the trend of mechanization has gradually penetrated into all construction links.

Comparison of manual operation and multi-arm rock drilling rig construction

1. Technical comparison between manual operation and multi-arm rock drilling rig

For manual operations, after the measurement, the excavation trolley is pushed to the front of the tunnel face, the worker moves the pneumatic drill onto the trolley, and holds the pneumatic drill to drill and charge the tunnel face, then remove the trolley and withdraw Personnel, machinery, remote control blasting. Then carry out ventilation and dust reduction, safe discharge of risks, and slag discharge; when using the dobby rock drilling rig, wait for the trolley to be in place, and the operator will operate the trolley to perform drilling. After the drilling is completed, the operator will drive the trolley to withdraw. Outside the cave, a series of processes such as blasting, ventilation and dust reduction, safe discharge of risks, and slag discharge are carried out. During the drilling process, the angle, position and depth of the drilling of the multi-arm rock drilling rig can be controlled more precisely under mechanical operation, which greatly reduces the various deviations that may occur in manual drilling and reduces the excess Digging the situation. Moreover, during the whole process, the number of operators is greatly reduced, and the distance from the face of the face is relatively long, which guarantees the personal safety of the workers. And the multi-arm rock drilling rig can be equipped with drill rods of different sizes to drill holes of different sizes.

2. Comparison of construction quality between manual operation and multi-arm rock drilling rig

When the tunnel excavation is carried out manually, the worker holds a pneumatic drill to drill the face of the tunnel. People need to control the angle, depth, and speed of the drill hole. This will greatly reduce the accuracy and quality of the blasthole, and there will be a lot of manual work. In the end, over-excavation and under-excavation were caused, which caused a series of problems in subsequent construction. When using multi-arm rock drilling rigs, the depth and angle of the drill rod can be designed in advance. Once the positioning is completed, there will be no deviation like manual drilling. In this way, the quality and accuracy of one-time forming technology of smooth blasting, which is currently widely used, is guaranteed. At the same time, the problem of over-under-excavation control in tunnels is greatly improved.

3. Comparison of manual operation and multi-arm rock drilling rig construction

(1) Improved drilling efficiency. According to the drilling experience at the entrance of the Xuanfengling Tunnel on the Hangzhou-Shaotai Expressway in Zhejiang Province, the drilling time of one hole is about 2 minutes by using a trolley, while the time for drilling one hole is about 20 minutes with the manual drilling. Using the full-face footage method, the average drilling time per cycle of manual excavation is about 6 hours, and the average drilling time per cycle of excavation using the dobby rock drilling rig is 2.5 hours. The drilling time is about 3 hours less than that of manual excavation. ~ 4h.

(2) The difficulty of drilling is reduced. The robot arm of the trolley can move and rotate flexibly, and the length is enough to drill different angles, different heights, and different types of blastholes.

(3) Reduce the number of personnel. For manual excavation, each shift requires about 9 workers to work at the same time. Dobby rock drilling rigs only need 3 to 4 workers to complete the same work.

(4) Reduced pollution. The multi-arm rock drilling rig is powered by electricity, clean energy, and also reduces the impact of noise, sewage, and dust on the environment and worker health during drilling.

(5) Improved safety. The operator controls the operating lever inside the trolley to perform operations, and the operating room is about 10m away from the face of the tunnel, effectively avoiding the accident of the collapse of the surrounding rock.

4. Economic comparison of manual operation and multi-arm rock drilling rig

When using a multi-arm rock drill rig, the material cost and mechanical cost are higher than manual drilling. The main reason is that the cost of the multi-arm rock drill rig is higher, and the life of the drill pipe is much lower than that of the commonly used handheld two-eight drill. , Resulting in faster parts loss and higher replacement and maintenance costs. However, due to the greatly reduced number of personnel, labor costs have been greatly reduced. In general, although the use of multi-arm rock drilling rigs is more costly than manual operations, the speed of project excavation has been significantly improved, so it has a great advantage in project progress and greatly shortens the construction period. At the same time, the multi-arm rock drilling rig controls the drilling more accurately, reduces the amount of over-digging and under-digging, and reduces the loss caused by over-under-digging.

5. Comparison of construction safety between manual operation and multi-arm rock drilling rig

If manual operation is used, when drilling on the face, the operator holds the pneumatic drill close to the face for construction. If the surrounding rock near the face is poor and the soil is loose, the impact caused by the drilling may cause collapse, which is easy to cause Casualties. In addition, there are more people working at the same time when drilling manually, which is likely to cause multiple casualties. When a multi-arm rock drilling rig is used, the operator is far away from the face of the drill, and the operator is in the operating room of the rig, even if it is dangerous, it can also play a protective role; manual operation requires about 6 pneumatic drills, which will cause A lot of noise and dust make the working environment extremely poor, and the wrist repeatedly exercises for a long time, causing frequent occupational diseases and causing great harm to the health of workers. When using a multi-arm rock drilling rig, the entire operation process basically has no air pollution, less noise, less sewage, and low construction intensity. The working environment of workers is greatly improved.

Advantages of using multi-arm rock drilling rigs

①Improve the level of mechanized construction equipment by introducing large-scale tunnel equipment, promote the development of tunnel construction quality, and further distance it from developed countries.

②With the increasing number of mountainous and hilly areas in highway construction, the proportion of highway tunnels is gradually increasing. The mechanized construction of tunnels has obvious economic benefits and safety, which can greatly improve the construction environment and fully implement the "people-oriented" concept.

③Mechanized construction is an important means to reduce labor intensity, improve work efficiency, speed up construction progress and ensure construction quality. Compared with manual work, it has great advantages. The mechanized construction of highway tunnels has obvious characteristics in terms of construction technology and equipment. The main features can be summarized as:

a. Able to complete difficult and dangerous construction tasks, with guaranteed quality of operation;

b. Can greatly improve labor productivity and speed up the progress of the project;

c. The safety of construction production has been greatly improved, and the environmental conditions of construction work have been greatly improved.

Summary：

At present, the main excavation method for mountain highway tunnels is drilling and blasting. Nowadays, pneumatic rock drills are mainly used in China for manual operation. However, this method has relatively slow drilling speed, poor operating environment, relatively large over-excavation and under-excavation, and many potential safety hazards, which restrict the rapid development of tunnel construction technology. Not in line with the "people-oriented" concept. The construction of the multi-arm rock drilling rig not only reflects its advantages in terms of construction schedule, quality, safety, etc., but also provides great help to the development of tunnel mechanization. This article compares the technology, quality, rock drilling, economy and safety of manual operation and multi-arm rock drilling rig drilling and blasting. It mainly compares the construction process, construction characteristics, and staffing in detail. Boom rock drilling rigs are more in line with today's mechanized development of construction roads. The advantages of multi-arm rock drilling rigs will become more and more obvious, and the prospects are bright, which is the main direction for the development of tunnel drilling and blasting construction in the future.