Analysis on the scheme of double peak tunnel construction

The Shuangfeng Tunnel belongs to the S111 contract section of Jinhua Section of Zhuyong Expressway in Zhejiang Province and the S1 contract section of Taizhou Section. It is located in Shuangfeng Township, Chun'an County, Jinhua City. It is designed according to the standard of one-way two-lane tunnel separated by expressway. The tunnels are 6180m and 6187m long respectively. The tunnels around the S111 contract section are 3255m long and 3242m. S111 contract section has a contract period of 26 months. The tunnel is a controlled construction period. The planned start date is January 17, 2005, and the planned completion date is March 16, 2007. The construction of the project can be divided into two stages. First, the previous period is 2005. The tunnel is in the form of a large package. The construction teams are constructed by two construction teams. The second is the construction of the project department with labor services from 2006 to the present. The original two construction teams were withdrawn.

Due to various factors, the actual completion date is expected to be until June 2008. Among them, the construction concept of double tunneling and short tunneling is proposed. Based on the principle of objective truth, this paper analyzes from many aspects of construction. The purpose is to take the essence and discard the dross. In the future, similar construction will be used to avoid weaknesses, and the tunnel construction management will reach a new level.

2 organization management

2.1 Strengthening ideological education and team building

After the bidding for this project, the company immediately transferred all aspects of management talents to set up the project department, and was entrusted by the company to be responsible for the construction management activities of the project. It should be said that the company is all strong and brave, the overall quality is high, everyone's work is very enthusiastic, morale is very good, they want to catch up with the work. But most of the people used to work on different projects. They have different ideas, characters, and ways of doing things. They need a break-in period. The main management of the project department was forced by the construction period pressure to grasp the construction production, neglecting the communication between the internal departments of the project, especially between the members of the leadership team, so the operation process A lot of detours have been taken, resulting in misunderstandings and differences, which have adversely affected project management. If we can pay attention to employees' ideological education and team building in a timely manner, speed up the integration of the entire project department, and exert collective strength as soon as possible, the results will be much better than the actual situation. After nearly a year of this situation, the company and the project were aware of the problem, and then improved and strengthened through meetings, seminars and other forms.

2.2 Strengthening scientific management

The double-peak tunnel has a single hole of 6187m and is a special long tunnel. It is the first in the history of our company's highway tunnel construction. More than 3,000 m in a single port, no horizontal holes, single-head ventilation, and only 26 months of construction, these are a new topic in front of the construction team. Due to the large length of the tunnel construction, sometimes there is no scientific judgment in the decision-making major program, and there is no layout for the characteristics of the special tunnel, such as the configuration of high-pressure feng shui, the ventilation after the hole depth exceeds 1500m, the overall process arrangement, etc. It is still based on the understanding of the short tunnel, which is bound to leave hidden dangers for later construction. With the continuous exploration and summarization, many aspects have been greatly improved in the later construction.

2.3 Correct positioning of progress targets

Due to the special situation of the double-peak tunnel, the construction period is heavy and the task is heavy. Therefore, the project department has always placed the progress in the middle of the construction and production, and any problem gives way to the progress. It is also based on this guiding ideology that at the beginning of the game, the project department was in the forefront of the construction of the bridge, and the construction of the bridge tunnel was part of the whole section (磐安), but a problem appeared. The tunnel team is fancy that the project department is eager to grasp the weakness of the schedule. If the project department is dissatisfied with the management of the project department, it will stop the work. The project department also meets some unsatisfactory requirements of the team in order to keep the progress, which greatly reduces the project management. Small, it will make the construction difficult. This should be a common problem in the current project management. In addition to strengthening contract management, we should pay attention to skills and strategies, correctly and rationally understand the progress issues, and avoid becoming the soft underbelly in project management. When a dispute arises between the project department and the team, you can consider adhering to the agreement, and don't easily accommodate it, so as not to encourage the wrong habit. If necessary, the cold treatment should not be anxious, become passive and take the initiative, maybe it will not wait for three or two days and things will develop to the good side. From the point of view of the general ledger, this treatment did not delay the construction period, but the smooth management of the government order was smooth, effectively ensuring the target of the construction period.

3 construction management

3.1 personnel, optimized equipment for mechanical equipment

According to the construction characteristics of the double-peak super-long tunnel, the parameters of the drilling and blasting depth, the one-time blasting capacity and the rock transport capacity, the air pressure air supply capacity and the process cycle time are determined to determine the double-peak tunneling scheme using artificial drilling and blasting. The method works, the support adopts the artificial spray concrete method, and the second lining adopts the full-section hydraulic trolley construction. After the overall construction plan is determined, what is to be done immediately is the allocation of construction personnel and construction machinery and equipment. This tunnel is a special long tunnel. It cannot be considered in accordance with the standards of small and medium tunnels that have been constructed in the past. It is necessary to carry out special tunnels, and push back according to the planned objectives. How much equipment configuration is required to ensure the realization of these goals. How long does it take to get out of the eye, and how long it takes to get out of it, but how many people, how many guns, how many cars, etc. must be guaranteed. Finally, according to the group plan and plan goals.

Every 2 groups of work, 1 set of rotating rest and concrete support personnel 15 2 lined personnel 25 two trolleys, concrete crews, waterproof boards, trolleys in place of personnel sharing management, drivers, handymen 30 also include electricians, repairmen , air compressor, concrete pump truck operator pneumatic rock drill YT2864J35 22 holes when drilling, other spare electric air compressor 4L20/820m35 each air compressor for 5~6 guns using side loader ZLC40B3m3 2 At the same time, the right tunnel-mounted dump truck CQ326020t9 is shared by the two tunnels. The two excavators are arranged to face the top of the excavator. The excavation two lining trolleys are 12m long, one of which is an enlarged section axle. The practice of ventilation in the 200kW 1 hole of the flow fan proves that the above configuration can basically meet the requirements of the plan, which is in line with the actual situation at that time. However, it seems that if you can press the dual-tunnel single-distribution and long tunnel short-selling ideas early, there will still be optimization in the configuration of personnel and equipment. For example, the power of the ventilator is too large (after adjustment to 255 kW), and only one of the two lining trolleys can be used (the normal section and the enlarged section can be constructed after the modification), and the corresponding two lining personnel can also be reduced. Other materials such as wire and cable, high-pressure air pipes, air compressors, transformers, etc., can be reduced accordingly, so tunnel construction costs will definitely decrease.

3.2 Refinement goals, phase control

Once the construction objectives are established, they must be carried out unwaveringly according to the established goals. In order to ensure the realization of the target, the construction plan is coordinated and continuously optimized, the objectives are refined, decomposed, and the responsibility objectives are implemented to the teams and individuals. Implement quantitative management of process indicators, sign construction responsibility documents with construction teams and individuals, and link construction workers' wage income with construction quality, safety, and progress indicators. For example, when I first came into the game in 2005, the project department made a phased arrangement for the tunnel construction. Before May 10, the tunnel excavation, slope treatment and pipe shed construction were completed. Before the 25th, the 28m weak surrounding rock was safely passed. Before the 25th, the first tunnel construction in the whole section took the lead in breaking through 100m. At the same time, the project department needs which materials are needed, when will they be present, and who will implement them? What tasks should be completed on the construction site every day, and if there are delays, how to recover, etc. Detailed arrangements. Arrange early to make arrangements, check the implementation of the evening meeting, a summary of three days, then open a regular meeting every week, invite the command and supervision to participate. In this way, several phased goals have been completed with trepidation. For example, in order to ensure the excavation progress, the total operation time per excavation should be controlled within 9.5h, the ventilation discharge is 0.75h, the drilling time is 4.0h, the exit is 4.0h, and the measuring line is 0.75h. To achieve these goals, A duty room is set up at the tunnel entrance, and the time for each process personnel to enter and exit the hole is signed and recorded. Finally, the team is rewarded and punished according to the record. These measures have proved to be very effective. In addition, to do a good job in on-site construction management, it is necessary to arrange the construction process reasonably and focus on the process connection. The process flow should be smooth, the process connection should be compact, and the implementation of the problem must adhere to the work style of one step.

3.3 Implementation of responsible cost management

Since the departure of the two tunnel teams, the project department began to carry out labor service construction, and the management of the project department has been significantly strengthened, but there have been many new problems. For example, the wage problem is sometimes delayed due to the difficulty of capital turnover, and the labor service class is beginning to be unstable, absenteeism or even strike. There is also the labor team's own anti-risk problem. The project department quantifies the labor volume and signs the labor agreement. However, if the workers do not meet the expected value, they will choose to leave. If they carry out the monthly subscription, they will not be able to mobilize the work enthusiasm. Negative absenteeism. These problems add difficulty to project management, and only continue to explore good solutions. The biggest problem of labor contracting is the material problem. Due to the complexity of tunnel construction, some materials have different discrepancies with the design. Therefore, only the limit material picking can not completely eliminate the material waste on the site.

Finally, the project department sent two technicians to take charge of material consumption management, on-site measurement, and cross-section and detailed records every meter. Without the signature of these two technicians, the Ministry of Security will not issue materials. For the part that exceeds the reasonable amount, it will be deducted from the work cost according to a certain percentage. The small parts required for construction shall be packaged according to the quota and on-site test conditions, and the price shall be discounted according to the quantity, and shall be purchased and stored by itself. After adjustment, the large material has been well controlled, but the small material part is difficult in specific quantitative, so there may be a certain dead angle, there is still room for tapping potential and increasing efficiency.

The cost of a civil engineering project should account for 60%~70% of the total cost. It must be highly valued. To carry out responsibility cost management, we should first start with material management.

4 technical management

4.1 Solving the problem of ventilation difficulties in long tunnels

When the tunnel depth is within 1500m, the general press-in ventilation is adopted, which can ensure the ventilation effect inside the cave. When it exceeds 1500m, the air quality of the face is reduced due to the influence of depth and the blockage of the two-liner in the hole. There is a certain amount of airflow but the wind pressure is not enough, and there is not enough pressure to bring out the dirty air inside the hole. After testing, even if it is replaced by a high-power fan, there is no obvious effect.

Finally, the tunnel adopts the tunnel-type combined ventilation, which has achieved obvious results. Through the cross-hole connection between the left and right tunnels, the left line of the tunnel is used as the air inlet, and the right line of the tunnel is used as the air outlet. An axial fan is arranged on the right side of the horizontal tunnel of the right tunnel. The air duct is connected to the face of the hand, and the dirty air of the right hole is blown out. A jet fan is arranged on the left side of the horizontal hole to guide the blown air. The left hole; the dirty air of the right hole that has entered the left hole, flows to the left hole in the direction of the hole in the left hole under the action of a jet fan installed in the left hole. The fresh air on the left side of the left hole is provided by another axial fan installed in the right hole. After passing through the horizontal hole, the air cylinder directly extends to the left hole face, and the dirty air in the left hole is pushed out. The dirty air from the right hole is discharged to the left hole. As the face advances, the front side of the driving cross hole, the fan moves forward, and the rear horizontal hole is blocked, so as to avoid mixing the left and right holes. Ventilation of the tunnel, the ventilation pipe always needs only the sum of the lengths of the two transverse tunnels, which reduces the ventilation cost of the tunnel, improves the ventilation effect inside the tunnel, and accelerates the tunnel construction progress.

4.2 Reduce the dust concentration in the tunnel

The source of dirty air in the cave is partly caused by the incomplete combustion of the mechanical vehicle and the chemical action of the explosive. Some of it is caused by the dust generated by blasting, shotcreting and other acts, so the dust removal is also very good for creating a good air environment inside the cave. Great effect. In addition to the dust collection device, high pressure water curtain method can be used to reduce dust.

A 50mm steel pipe is placed along the contour of the tunnel vault near the face of the face (close to the natural stacking edge of the blasting stone). A 2.5mm small eye is drilled every 5cm on the pipe wall, and a high-pressure water pipe is connected to one end of the steel pipe. High pressure water is connected 10 minutes before each blasting. The water is sprayed in a dense mist, and the air of the wet face is aired. At the same time, the dust of the blasting stone is closed by the water curtain and absorbed in the face of the face. The injection time can be according to the specific situation. Master, generally controlled within 15min. The high-pressure water curtain method is simple and easy to implement, and the cost is low, which is worth promoting.

4.3 more design abandoned market location

The original design is about 3km away from the tunnel entrance. The road is not good. It has to go through a township street. The vehicle will go back and forth for about 40 minutes. After repeated negotiations with the headquarters and the local government, the project department will pay a certain amount of farmland for re-cultivation. The deposit is given to the command department, and a new market is added to the mountainous area less than 1km away from the tunnel entrance. The transportation distance is shortened by 2km, and the vehicle takes only about 20 minutes to go back and forth, which greatly improves the tunnel exit speed. At the same time, special personnel are sent to repair and maintain the road surface, remove the stones, fill the pits and fill the holes, so that the vehicle can run smoothly and normally.

After changing the location of the market, the construction progress of the entire tunnel has been improved, directly reducing the excavation cost by about 4%.

4.4 Improve the quality of tunnel construction

Before the tunnel starts, in order to ensure the measurement accuracy of the long tunnel, the project department will hire a qualified measurement company to help with the wire retest. The company adopted the GPS satellite measurement system, and connected the two front and back sections with the wires of our department. The tunnel monitoring wire network was buried in the tunnel mouth and the measurement results were issued. After one year of construction, the company was asked to retest and check whether the piles were damaged or offset. After GPS measurement and control, more than 6000 m tunnels are well controlled, and the through-holes are not more than 5 cm. In the tunnel excavation, due to various reasons, the tunnel over-excavation is more serious, which is a good control. For this problem, the project department decided to purchase a Beijing-made DJ2 laser cross-section detector to guide and inspect the tunnel excavation section. For the tunnel rock face after the initial spray, it is necessary to carry out the next process when the measurement section has no problem in measuring the section, and the problem is dealt at the source to avoid burying the future trouble. The problem was solved to a large extent in the construction section. In terms of material weighing, concrete mixing, strength control testing, etc., more advanced control methods and equipment have been used as much as possible, and the results are ideal.

4.5 Science and technology breakthrough bold innovation

At the beginning of construction, the air compressor at the tunnel entrance is arranged in a single tunnel, and the pipe is routed separately. The amount of air duct is large, and as the tunnel face moves, the air supply volume of the single tunnel is also significantly weakened. In response to this situation, QC activity team members actively use their brains, consult various materials and data, and boldly put forward the idea of ​​two-way singles. The original five air compressors were connected in series and combined into eight to reduce the idling of the air compressor. The remaining two air compressors were moved into the hole from the hole and installed in the enlarged section closer to the face of the hand. The single ducts of the original two tunnels are combined, and only one pipe is installed, and is distributed to the face of the face through a horizontal hole not far from the working surface. After adjustment, the utilization rate of the air compressor has been improved, the power consumption has also been reduced by about 10%, and the high-pressure air duct usage has been reduced by about half. According to this idea, the cables, wires, transformers, high-pressure water pipes, etc. in the hole have also been adjusted, and the amount of materials used in the tunnel has been reduced a lot. In addition, the cave is designed with an emergency parking belt and an enlarged section of the cross-section of the traffic. The section is larger than the normal tunnel section, so the original normal section two-liner can not be used. If it is processed and purchased, the cost is too large.

After everyone's brainstorming, it was decided to transform the original trolley, that is, add a large template to the original trolley side and support it on the template surface of the original trolley with steel. Only by adding a part of the formwork and the section steel, the problem of the trolley of the enlarged section is solved, and the input cost of the two-lined trolley is saved. In addition to this, there are other small creations, gizmos, and contributions to improving the level of tunnel management technology.

5 Conclusion

The construction experience of the double-peak tunnel indicates that in the future, the long tunnel should be constructed according to the guiding principle of double tunneling and short tunneling, that is, the construction working surface should be controlled within the range of 200~300m from the head surface, construction equipment And the personnel are concentrated in this 200~300m, and the formed part will only play a construction aisle from a certain angle. To ensure long tunnel short breaks, one guarantee is to use tunnel ventilation, so that the ventilation pipe only appears near the face of the hand. The other guarantee is that the tunnel must pay attention to the balanced construction, the flow should be organized in the tunnel, and each process should be carried out in a smooth manner. In the short tunnel construction, various contradictions are not prominent, but in the long tunnel, if you pay little attention to it, there will be how long the tunnel is and how long the battle line will be, which is unfavorable from any angle. In the early stage of tunnel construction, due to the fear that the pavement layer lean concrete will be crushed by heavy trucks, the cushion will start late, resulting in poor image inside the cave. There are puddles and mud everywhere, and the tires of the cart are seriously worn. Losing points in civilized construction is not worth the candle. Then the actual situation proves that the pavement cushion can be considered first, as long as there is no vain at the bottom, there is not much damage after the heavy truck. Other processes in the tunnel should also be promoted in a step-by-step manner. As long as the support, the second lining and the road cushion can keep up with the face of the face and maintain a distance of 200~300m, then a long tunnel short hit is achieved to some extent, no matter the scene. Civilization construction or tunnel cost control should be greatly improved.

Each tunnel project has its own characteristics, and the problems encountered are also ever-changing. It is impossible to generalize, but through the surface to see the essence, there are always some things that can be followed regularly. These laws can be mastered and utilized. This paper summarizes the aspects of organization management, construction management and technical management of the tunnel, highlights the guiding ideology of double tunneling and short tunneling, and provides a reference for subsequent construction of similar projects, which is valuable for tunnel construction. experience.

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