The essence of the new Austrian law 20, what is the difference between the new Austrian law and the

1. The principles are different.

New Austrian Law. It is necessary to fully protect the surrounding rock and reduce the disturbance to the surrounding rock; Give full play to the self-supporting capacity of the surrounding rock.

New method, full-section excavation; The use of advanced support and reinforcement measures to reduce or avoid the deformation of the surrounding rock.

2. Some principles are different.

The new Austrian method makes full use of the self-supporting normal cracking capacity of the surrounding rock and the spatial restraint of the excavation face, adopts the anchor rod and shotcrete as the main support means, reinforces the surrounding rock in time, restricts the relaxation and deformation of the surrounding rock, and guides the design and construction of underground engineering through the monitoring and measurement of the surrounding rock and supporting structure.

The new method, especially under weak and broken geological conditions, strengthens the advanced core soil and tunnel surrounding rock of the tunnel face by taking pre-restraint and restraint measures.

The advantages of the new Austrian construction are:

Maximize the strength of the original rock mass of the surrounding rock around the tunnel.

Timely support and close contact with the rock surface to form the integration of the surrounding rock and the lining, greatly reduce the required support resistance, and save the component support that needs to be dismantled after erection in the traditional construction method.

The use of thin layer support reduces the number of excavations and the number of lining masonry.

The application of measurement technology makes the design and construction more reasonable.

In weak surrounding rock, poor geology and shallow buried tunnels, it can show its superiority.

The disadvantages of the construction of the new Austrian method are:

The technical requirements are high, such as smooth blasting, anchor spray support, measurement means, etc.

In order to carry out the observation task in the cave, the construction technician must enter the hole on time and carefully observe the working face and construction site. Ignoring any of these links can lead to undesirable consequences.

(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 "pipe advancement, strict grouting, short excavation, strong support, diligent measurement, and fast closure".

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 in terms of the redistribution of stress.

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.

The new Austrian method is to apply the theory of rock mass mechanics, take the maintenance and utilization of the self-supporting capacity of the surrounding rock as the base point, use bolts and shotcrete as the main support means, timely support, control the deformation and relaxation of the surrounding rock, make the surrounding rock an integral part of the support system, and guide the methods and principles of tunnel construction and underground engineering design and construction through the measurement and monitoring of the surrounding rock and support.

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 shotcrete, anchor rod, steel mesh and steel support, which is called the initial flexible support, which is the support work that 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 new Austrian method is a construction method that uses shotcrete anchors as the main support means to monitor and control the deformation of the surrounding rock, so as to give full play to the self-supporting capacity of the surrounding rock.

As with the name of a game, I've played it before.

A method of construction.

The new Austrian method is to apply the theory of rock mass mechanics, take the maintenance and utilization of the self-supporting capacity of the surrounding rock as the base point, use bolts and shotcrete as the main support means, timely support, control the deformation and relaxation of the surrounding rock, make the surrounding rock an integral part of the support system, and guide the methods and principles of tunnel construction and underground engineering design and construction through the measurement and monitoring of the surrounding rock and support.

1. Smooth blasting 2, anchor spraying support 3, monitoring and measurement.

These are the means of implementation or external manifestations of NATAM, and in order to understand NATAM, we must understand it in essence. The new Austrian method is not a construction method, it is a change in design philosophy.

To put it simply, before the advent of the new Austrian law, people passively believed that all supporting structures were passively subjected to the pressure of the surrounding rock. The new Austrian method completely changes this concept, and the surrounding rock is not only an active load, but also a load-bearing structure. The guiding ideology of the new Aofa is to make full use of the bearing capacity of the surrounding rock itself and protect the surrounding rock as much as possible, so smooth blasting and weak blasting are used to disturb the surrounding rock as little as possible.

Anchor spray support can close the surrounding rock in time, minimize the loosening of the surrounding rock, and control the deformation of the surrounding rock. Monitoring and measurement can intuitively monitor the convergence and deformation of the surrounding rock, because at present, the finite element analysis of tunnels, especially deep buried tunnels, is basically nonsense. When you enter the tunnel and see the face of the tunnel once, you will despair of the model you have built.

Before the advent of the new Austrian law, the initial support or temporary support of the tunnel was mostly to ensure the safety during construction, and the lining (integral lining) was the pure supporting structure; At present, the new Austrian method mostly adopts the composite lining of the initial support and the secondary lining, both of which are designed according to the permanent structure. Theoretically, the initial support bears all the loads, and the secondary lining belongs to the safety reserve. In the actual design, taking into account the current domestic awareness of the tunnel NATM concept, the construction level and the construction status, the secondary lining takes into account a part of the surrounding rock pressure, or 30% or 50%.

Of course, these are all changes in people's mindsets. The surrounding rock where the tunnel project is located is objectively existent, and it is still the surrounding rock from beginning to end, and will not change because of our different understanding of the surrounding rock. So, I personally think that even before the advent of NATM, many tunnels were constructed in a way that embodied the idea of the new Austrian law.

It was only the Austrian scholar Professor Rabschwitz who first formally put forward this idea and patented it, which led to the NATM --- New Austrian Tunnel Engineering Method that we have today. In recent years, with the improvement of anchor spraying technology, measurement technology and blasting technology, the new Austrian method has also been developed by leaps and bounds, and has become an indispensable method for the design and construction of tunnel engineering.

I don't know if you understand? The essential difference is the understanding of the surrounding rock of the tunnel, which was previously regarded as a simple load by the new Austrian method, while the new Austrian method regarded the surrounding rock as both a load and a bearing structure.

It's the latest way to learn.