I would like to ask about the principle of tunnel construction? 20

At present, there are many mountain tunnels that use the drilling and blasting method, and there are also roadheaders (TBM). Municipal subway tunnel adopts shield construction, and the use of immersed tunnel across the river also has, and its construction method is different, and its design theory may be different.

Tunnel construction: 1 There are many hidden and unknown factors.

2. The working space is limited, the working face is narrow, and the construction process interferes greatly.

3. The cyclical nature of the construction process is strong, because the tunnel project is longitudinal, and the construction is strictly in accordance with a certain sequence of circular operation, such as excavation, it must be in accordance with the order of "drilling-charge-blasting, ventilation and slag".

4. The construction operation is comprehensive, and multiple processes (excavation, support, lining, etc.) are carried out in the same working environment.

5. The geomechanical state of the construction process is changing, and the physical and mechanical properties of the surrounding rock are also changing, so the construction is dynamic.

6. The working environment is harsh, the working space is narrow, the construction noise is large, dust, smoke, humidity, dark light, poor geological conditions and safety problems bring unfavorable working environment to the construction personnel.

7. The operation is risky. Risk is related to concealment and dynamics, and during the construction process, the construction personnel must pay attention to the risk of tunnel construction at all times.

Like rat burrowing, circular sections are the least likely to collapse.

The force on the tunnel is the force on the arch.

You can go and see how the shield machine works

Tunnel construction methods, as follows:

1. The full-section excavation method, the full-section excavation method is a construction method that blasts and forms according to the design contour and then builds the lining. Applicable conditions, I IV grade surrounding rock, when used in grade surrounding rock, the surrounding rock should have the conditions to maintain its own stability during the period from the full section excavation to the initial support. There are drilling trolleys or self-made operation benches and high-efficiency shipping machinery and equipment.

The length of the tunnel or the length of the construction section should not be too short, and according to experience, it should not be less than lkm, otherwise the large-scale mechanized construction will be adopted, and its economy will be poor;

2. Step method construction, step method is to excavate the upper half section first, to excavate the lower half section at the same time after excavation to a certain length, and the upper and lower half sections go hand in hand at the same time. In recent years, due to the design of large-section tunnels, there are three-step temporary inverted arch method, or even multi-step method, and the step excavation method can have enough working space and considerable construction speed. However, there is interference in the upper and lower operations, and although the step excavation increases the number of disturbances to the surrounding rock, the steps are conducive to the stability of the excavation face.

Especially after the upper excavation support, the lower part of the operation is safer, but attention should be paid to the influence of the lower part of the operation on the stability of the upper part;

3. Annular excavation to retain the core soil method;

4. Cross-partition method CRD method;

5. Double-sidewall guide pit method.

Highway Law of the People's Republic of China

Article 47 Within 200 meters around large and medium-sized highway bridges and ferries, above highway tunnels and outside the openings, and within a certain distance on both sides of highways, no sand digging, quarrying, soil extraction, dumping of waste, blasting operations and other activities that endanger the safety of highways, highway bridges, highway tunnels and highway ferries shall not be carried out. Within the scope of the preceding paragraph, if it is necessary to build embankments, compress or widen the riverbed due to emergency rescue and flood control, it shall be reported in advance to the competent departments of transportation of the people's governments of provinces, autonomous regions and municipalities directly under the Central Government in conjunction with the competent departments of water administration, and effective measures shall be taken to protect the safety of relevant highways, highway bridges, highway tunnels and highway ferries.

At this stage, what are the main tunnel construction methods in China? What's the basics? The following is the relevant content of the construction methods and professional construction terminology of Zhongda Consulting to sort out the construction methods of tunnels, and the basic situation is as follows:

In order to help the personnel of construction enterprises to further understand the construction method of the tunnel, Zhongda Consulting takes the construction of the new Austrian tunnel as an example, and the main contents are as follows:

Under the premise of using the bearing efficiency of the surrounding rock itself, the new Austrian method adopts millisecond blasting and smooth blasting technology to carry out full-section excavation construction, and builds the tunnel body with the formation of composite inner and outer two layers of lining, that is, the outer layer support form of sprayed concrete, bolts, steel mesh and steel support is buried, which is called the initial flexible support, and the support work must be carried out immediately after the excavation of the tunnel body. Because the in-situ stress contained in the mountain is redistributed due to the excavation into a hole, the tunnel space can be maintained stable by the cavity effect, that is to say, the bearing of in-situ stress is mainly the surrounding rock mass itself, and the role of the initial spray anchor flexible support is to maximize the bearing capacity of the surrounding rock mass itself, and the second lining is mainly to play the role of safety reserve and decorative beautification.

The applicability of the new Austrian method is wide, and China has been successful in the construction of sub-clay and loess tunnels.

Scope of application of the new Austrian law:

1. Medium rock mass with long self-stabilization time;

2. Weakly cemented sand and gravel and unstable conglomerate;

3. Strongly weathered rocks;

4. Rigid-plastic clay argillaceous limestone and argillaceous limestone;

5. Hard clay, there are also clays with hard interlayers;

6. Slightly fractured, but rarely clay-like rock mass;

7. Under the condition of high initial stress field, hard and curved variable hard rock;

The main principles of the construction of the new Austrian method:

1. Fully protect the surrounding rock and reduce the disturbance to the surrounding rock.

2. Give full play to the self-supporting capacity of the surrounding rock.

3. Close the supporting structure as soon as possible.

4. Strengthen monitoring and guide construction according to monitoring data.

It can be summarized as "short footage, weak blasting, tight sealing, early anchoring, and frequent measurement". Because the main bearing part of the tunnel is the surrounding rock, the supporting structure plays a role in exerting and protecting the bearing capacity of the surrounding rock. In the theory of statics, the structure of the tunnel can be regarded as a cylindrical structure composed of the bearing ring of the rock mass and the supporting lining, and the closure of the bearing ring plays a key role, so the integration of the surrounding rock and the lining should be completed as early as possible in the initial lining to ensure the stability and integrity of the lining ring.

Consider it from the distribution of stress weight. Full-section excavation is an ideal excavation method. Therefore, in the final analysis, the construction method should grasp a starting point, that is, to protect, mobilize and give full play to the self-supporting capacity of the surrounding rock, and on this basis, flexibly select the construction and auxiliary means according to the actual conditions of the project.

What are the most commonly used tunneling methods? What are the characteristics of each of them? If you want to know the answer, the following is the relevant content of the most commonly used tunnel construction methods sorted out by Zhongda Consulting, and the basic situation is as follows:

According to the different conditions of the tunnel crossing the stratum and the development of the current tunnel construction method, the tunnel construction method can be classified as follows:

1.Mountain tunnel: mining method (drill and blast method) and roadheader method (TBM), of which the mining method is divided into traditional mining method and new Austrian method.

2.Shallow burial and soft soil tunnels: open cut method, cover excavation method, shallow buried underground excavation method and shield method.

3.Underwater tunnels: submersible and shield tunnels.

1. Mountain tunnel construction method.

Mechanical ventilation must be used in tunnel construction. The ventilation method should be determined according to (tunnel length, construction method and equipment conditions), etc. Long tunnels should (with preference given to mixed ventilation methods).

When the main engine ventilation can not ensure the ventilation requirements of tunnel construction, it should (set up a local ventilation system, fan interval series or add another air duct to increase the air volume). If there is an auxiliary tunnel, it should be used as much as possible (tunnel ventilation). Tunnel excavation construction, the use of small guide pit before and after the full section blasting follow-up, in the same tunnel in the flat guide in front, the full section of the reaming light explosion surrounding rock into the arch shape is good, and then support, lining, high quality, fast progress, can ensure that the lining inside and outside of the beauty, the installation of waterproof board really play a waterproof role, to ensure that the lining does not seep and do not leak.

Second, shallow burial and soft soil tunnel construction methods.

The steel pipe technology of medium and long and large lock leg in the initial support construction of shallow buried soft soil tunnel is a strengthening technology to inhibit the subsidence and deformation of the primary support, and the technical parameters such as the diameter, length, quantity, and application timing of the steel pipe should be adjusted in time according to the surrounding rock situation and the deformation of the primary support. In the process of practice, the down-the-hole drilling rig should be used for hole formation and installation operations, considering the cost of the down-the-hole drilling rig, when the shallow burial of the weak surrounding rock needs to be strengthened, the longer the length of the section, the more considerable the economic benefits. Of course, this technology can also be considered as a conventional cave body initial support strengthening technology under other similar undesirable geological strips.

3. Underwater tunnel construction method.

The main construction methods used in the construction of underwater tunnels are: embankment open cut method, pneumatic caisson method, shield method and immersed tube method. The embankment excavation method is more economical, and it should generally be considered first when conditions permit.

The pneumatic caisson method is only suitable for smaller river channels where there is not much navigation. Because the shipping at the place where the underwater collapsed tunnel needs to be built is usually more frequent, the use of the embankment open cut method and the pneumatic caisson method interferes greatly with the water traffic, so the shield method and immersed tube method are mostly used in the construction of underwater tunnels for more than 150 years. After the 50s of the 20th century, major technical breakthroughs such as underwater joints and foundation treatment of the immersed tube method have been made, which greatly simplified the construction process, greatly improved the waterproofness of the tunnel, and can adopt a rectangular section that accommodates more than four lanes.

Under certain conditions, the immersed tube method tunnel covers shallow soil, the line is short, the cost of lighting and ventilation is small, the engineering and operating costs are low, and the use effect is good, so since 1965, more than 20 underwater road tunnels built in various countries around the world are mostly immersed tube method.