A support system to reduce deformations in structures around tunnel routes

Abstract

The present invention relates to a new support system for minimizing the deformation caused by tunnels excavated for any purpose in any area to the structures on the route.

Description

[0001] A SUPPORT SYSTEM TO REDUCE DEFORMATIONS IN STRUCTURES AROUND TUNNEL ROUTES

[0002] Technological Field:

[0003] The present invention relates to a new support system for minimizing the deformation caused by tunnels excavated for any purpose in any area to the structures on the route.

[0004] State of the Art:

[0005] Nowadays, it is common to see deformations on the ground surface above the tunnels opened. This issue is especially evident for tunnels manufactured via the NATM technique. Especially in these tunnels opened within the city, such as subway construction, deformations on the surface cause serious problems in the structures. Existing techniques to reduce these deformations generally use methods such as keeping the tunnel shoring system strong, making improvements inside the tunnel to target the building foundations, strengthening the tunnel face, grouting from the surface to target the building foundation or the substrates of the structure, ground freezing or ground heating.

[0006] Since ground loss occurs during tunnel excavation, deformations and displacements on the ground surface are frequently encountered. In order to reduce these deformations, methods such as trying to keep the tunnel shoring system strong, making improvements from inside the tunnel to target the foundations of the structure, increasing the face stability or grouting from the surface to target the foundation of the structure or the ground layers beneath the structure can be preferred. More costly methods such as ground freezing or heating are rarely used. The impact of preferred improvements often cannot be clearly determined. For this reason, the excavation is regularly monitored with instrumental measurements and additional measures are taken if deemed necessary.

[0007] When existing techniques are examined, it always remains a question mark what kind of improvement grouting and the like make on the ground. In addition, when injection is performed simultaneously with tunnel excavation, the ground becomes heavier, which can increase surface displacements. In the case of injections started before the tunnel excavation, the injection may not be fully penetrated under the target structure, core soil layer beneath the structure foundation remains unprotected because the injection is applied to the ground at an angle, if the injection pressure is kept high, the structure may be damaged even before the tunnel is opened due to heave, and if low pressure is used, the injected mixture cannot be refluxed into the ground as desired.

[0008] Among the existing techniques, ground heating and ground freezing methods are expensive methods because they require special technology and the application stage is more specific and are not preferred unless there is a very special and essential situation.

[0009] Another technique, temporary lowering of the ground water level, may cause an increase in the effective stress in the ground and cause settlement directly on the surface, so it should not be preferred in areas with structures above it. Continuous pumping will be required to keep the underground water level at a certain level, which will cause energy consumption during the tunnel excavation. In addition, legal difficulties may be encountered as these pumping operations will create an environmental impact in the relevant region.

[0010] The Chinese patent document numbered CN104895121 A, encountered in the literature research, describes a system designed under the building floor. In the mentioned document, pits are opened around the building ground and these pits are combined with the reinforcement layer. This method does not provide adequate support since it does not consist of a frame system consisting of fully anchored braced joints, as in the present invention, which is based on generating moment and displacement in the direction opposite to the vertical settlement on the beam element under the structure before the start of tunneling excavation.

[0011] In the Chinese patent document CN102704957 (A) numbered CN102704957 (A) encountered in the literature search, a method similar to the top down excavation method is mentioned in order to continue the use of the existing topography above the structure without disturbing the existing topography above the structure for the structure to be built underground, but it is not related to the present invention. It does not contribute to eliminate the deformations of the surrounding structures.

[0012] In the Japanese patent document numbered JPH1129949A encountered in the literature search, a system placed on the tunnel is mentioned. This system, which aims to prevent collapse in the tunnel floors, poses a danger to the tunnel as it is installed directly above the tunnel. It has no benefit for protecting building floors.

[0013] Consequently, a new support system is required in which the state of the art is exceeded, the disadvantages are eliminated.

[0014] Brief Description of the Invention:

[0015] The invention is a support system which exceeds the state of the art, eliminates the disadvantages and has some additional features.

[0016] The object of the invention is to provide a support system that reduces the effect of the displacements caused by the tunnel excavation on the related structures in urban underground tunnelling where critical structures (historical-military structures, critical infrastructure lines such as natural gas, sewer line, etc. are located.

[0017] In the invention, instead of making improvements in the tunnel ground, it is aimed to limit the displacements that will occur in the structures by transferring the loads that occur after the structure-ground interaction to this frame system with the principle that the frame system to be formed by passing through the regions where the displacements to be formed by the tunnel excavation are zero or minimized is minimally affected by the ground movement.

[0018] Unlike the methods used in the state of the art, the invention is a more controllable and directly targeted improvement or soil reinforcement method instead of improving the soil parameters mentioned in the present art to control the settlements on the surface. Horizontal reinforcement elements, which are an important element of the invention, were placed under the foundation of the structure by horizontal drilling to be anchored outside the turning point of the surface slump trough expected to occur depending on the tunnel diameter and depth. These elements, in a sense, act as rigid beams. The related horizontal beams will be fully anchored with piles that will act as columns and a frame system will be formed under the foundation. It will be ensured that the structure will be minimally affected by the deformations that will occur in the ground with the support of this frame system.

[0019] Description of the Figures:

[0020] The present invention will be described with reference to the accompanying drawings, thus the characteristics of the invention will be understood clearly. However, the aim of this is not to limit the invention with such certain embodiments. On the contrary, it is aimed to cover all alternatives, amendments and equivalents which may be contained in the field defined by the accompanying claims. It is to be understood that the details shown are only shown for the sake of illustrating the preferred embodiments of the present invention and presented for both illustrating the methods and for providing description of the rules of the invention and the conceptual features of the invention to be easily understood. In these figures;

[0021] Figure - 1 Front view showing the system of the present invention.

[0022] Figure - 2 Top view showing the system of the present invention.

[0023] The figures which enable to clarify this invention are enumerated as mentioned in the attached figure and they are given with their names herein below.

[0024] Description of the References:

[0025] 10.Tunnel

[0026] 11. Bored pile

[0027] 12. Circular sheath

[0028] 13. Horizontal beam 14. Pre-tensioning rope

[0029] A. Structure

[0030] B. Structure sub-foundation area

[0031] C. Excavation ground

[0032] D. Ground unaffected by excavation

[0033] Description of the Invention:

[0034] In this detailed description, the inventive support system is described by means of examples only for clarifying the subject matter such that no limiting effect is created.

[0035] Figure 1 shows the front view of the support system subject to the invention, and figure 2 shows the top view of the same. Accordingly, the support system is deployed in the sub-foundation area (B) of the tunnel (10) on the excavation ground (C). Structure (A) includes all types of structures located on the tunnel (10) route. Structure subfoundation area (B) is the area under the foundations of structure (A). Excavation ground (C) describes the ground that has collapsed due to tunnel (10) excavation. Whereas all systems prior to the invention provide solutions to improve the excavated ground (C) referred to herein, the invention utilizes the load applied to the ground by the structures (A) to direct the load to the ground (D) unaffected by the excavation. Ground unaffected by excavation (D) is not exposed to any collapse or displacement after the tunnel (10) excavation. For this reason, the structures (A) are prevented from being subjected to deformation.

[0036] In the invention, a row of horizontal beams (13) and bored piles (11 ) supported at their ends were used to direct the loads of the structures (A). The number of horizontal beams (13) varies depending on the length of the tunnel (10) or the number of structures (A). Accordingly, the invention comprises at least one horizontal beam (13) having a dimension longer than the width of at least one tunnel (10), which is positioned in the structure sub-foundation area (B), not including the excavation ground (C). There is a bored pile (11 ) at each end of the horizontal beams (13). Horizontal beams (13) transfer the loads of the structure (A) and the structure sub-foundation area (B) to the mentioned bored piles (11 ). Since the bored piles (13) are located on the ground (D) that is not affected by the excavation, the effect of collapses on the excavation ground (C) on the structures (A) is reduced.

[0037] As an alternative in the invention, bored piles (11 ) or horizontal beams (13) can be turned into an anchored system by tensioning them with pre-tensioning ropes (14). The pre-tensioning rope (14), by making a rigid connection with the bored pile (11 ) or horizontal beams (13), can both provide displacement limitation to support the fully anchored condition of the relevant region and reduce the displacements that will occur with the tunnel excavation by creating reverse moments on the horizontal beam (13) element with the foresee load.

[0038] In the invention, pressurized liquid or reinforced concrete + steel composite element is used as horizontal beam (13). Reinforced concrete + steel composite is advantageous in that the strength parameters required by using concrete and steel depending on the order of displacements depending on the diameter and depth of the tunnel (10) can be easily reached and it is easy to make it economically feasible. On the other hand, the basic principle of adding rigidity with pressurized liquid is that the pressure can be controlled by external intervention at any time, the pressure changes that will occur during the tunnel excavation can be monitored and the incompressibility of liquids is an important advantage. One, the other or both of these two methods can be used in the system at the same time.

[0039] In the invention, a circular sheath (12) is also used between the horizontal beams (13) to contain the settlements that may occur on the surface during excavation during horizontal drilling, and to ensure controlled placement of the horizontal beam (13). In addition, the sheath (12) ensures that the pressure generated inside the horizontal beam (13) in the event that it is formed with pressurized liquid is directed.

[0040] In the fluid pressure-based horizontal beam (13) method of the invention, the cavity in the horizontal beam (13) is pressurized with a fluid. The pressurization process is provided by a liquid drive tank and pump. Here, the liquid is guided into the horizontal beam (13) via sealed connections and the circular sheath (12).

Claims

CLAIMS1. A new support system for minimizing the deformation caused by tunnels excavated for any purpose in any area to the structures (A) on the route, characterized in that, it comprises the following;• at least one horizontal beam (13) having a dimension longer than the width of at least one tunnel (10), which is positioned in the structure sub-foundation area (B), not including the excavation ground (C),• at least one bored pile (11 ) at each end of the mentioned horizontal beam (13) in the ground unaffected by excavation (D) where the load from the horizontal beam (13) is transferred.

2. A support system according to claim 1 , characterized in that; it comprises reinforced concrete + steel composite horizontal beam (13) in order to ensure that the required strength parameters can be easily reached by using concrete and steel depending on the order of displacements depending on the diameter and depth of the tunnel (10) to be opened and to make it economically feasible.

3. A support system according to claim 1 , characterized in that; it comprises a horizontal beam (13) containing pressurized liquid in order to control the pressure at any time by external intervention, to monitor the pressure changes that will occur on it during the tunnel excavation and to benefit from the incompressibility of liquids.

4. A support system according to any one of the preceding claims, characterized in that; it comprises a circular sheath (12) between the horizontal beams (13) for retaining the settlements that may be caused on the surface by the excavation to be made during horizontal drilling, and for providing a controlled placement of the horizontal beam (13).

5. A support system according to any one of the preceding claims, characterized in that; the horizontal beam (13) comprises a circular sheath (12) for directing the pressure to be generated inside the same in case it is formed with a pressurized liquid.

6. A support system according to any one of the preceding claims, characterized in that; the length of the horizontal beam (13) is greater than the width of the tunnel (10).

7. A support system according to any one of the preceding claims, characterized in that; it comprises at least one pre-tensioning rope (14) which, by rigid connection with bored piles (11 ) or horizontal beams (13), is capable of both limiting the displacement to provide support for the fully anchored condition of the relevant zone and reducing the displacements that will occur with the tunnel excavation by creating reverse moments on the horizontal beam (13) element with the foresee load.

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