Advanced support structure for top arch of underground powerhouse

Abstract

The utility model provides a forepoling structure of an underground powerhouse top arch. The forepoling structure comprises a main variable tunnel top arch, a temporary anchor rod, a bent arc steel bar, a steel pipe limiting hole, a forepoling small guide pipe and a forepoling anchor rod. The temporary anchor rods are anchored in the top arch of the main transformer tunnel at equal intervals, and the exposed ends of the temporary anchor rods are close to the interface of the top arch of the main transformer tunnel and provided with hooks; the shape of the curved reinforcing steel bar is matched with the interface outline of the top arch of the main variable tunnel, and the curved reinforcing steel bar is fixedly connected with the hook of the temporary anchor rod to form a supporting foundation; the multiple steel pipe limiting holes are fixed to the bent arc steel bars according to the preset installation positions of the advanced small guide pipes and the advanced anchor rods. The advanced small guide pipes and the advanced anchor rods penetrate through the steel pipe limiting holes in a one-to-one matching mode and are installed in the main transformer tunnel top arch. The advanced support structure for the top arch of the underground powerhouse has the advantages that the advanced support structure can be applied to the top arch operation of the underground powerhouse, and the safety risk of the top arch of the extra-large-section cavern is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of underground power house construction, and specifically, to an advanced support structure for the top arch of an underground power house. Background Technique

[0002] During the tunneling excavation and support, when encountering poor geological sections such as faults, altered zones, and developed joints, advanced bolts and advanced grouting small pipes are usually used for advanced support to reduce the risk of block falling and collapse in the poor geological sections.

[0003] When constructing advanced bolts and advanced small pipes, they are driven into the rock formation along the periphery of the tunnel excavation outline at an external insertion angle of about 15°, and the tails are welded to the steel arch near the face.

[0004] The tails of the advanced small pipes and advanced bolts can only play their supporting roles when welded to the steel arch. However, for extra-large cross-section chambers such as underground power houses and main transformer chambers, the cross-section is too large, and the erection of the steel arch cannot play a good role in the stability of the chamber. Therefore, the method of erecting the steel arch is generally not adopted. Thus, even if there are poor geological sections such as faults, altered zones, and developed joints in extra-large cross-section chambers such as underground power houses and main transformer chambers, the support methods of advanced small pipes and advanced bolts will not be used.

[0005] However, the support effects of advanced bolts and advanced small pipes for poor geological sections such as faults, altered zones, and developed joints are relatively good. Therefore, how to transform the advanced support structure so that advanced bolts and advanced small pipes can be applied in the operation of the top arch of an underground power house is a technical problem that needs to be urgently solved by those skilled in the art. Content of the Utility Model

[0006] The purpose of the utility model is to overcome the deficiencies of the prior art, and thus provide an advanced support structure for the top arch of an underground power house that can be applied to the operation of the top arch of an underground power house and reduce the safety risk of the top arch of such extra-large cross-section chambers.

[0007] To achieve the above purpose, the technical solution adopted by the utility model is: an advanced support structure for the top arch of an underground power house, including the top arch of the main transformer chamber, temporary bolts, bent arc steel bars, steel pipe limiting holes, advanced small pipes, and advanced bolts;

[0008] The temporary bolts are anchored in the top arch of the main transformer chamber at equal intervals, and the exposed ends of the temporary bolts are close to the interface of the top arch of the main transformer chamber and are provided with hooks;

[0009] The shape of the bent arc steel bar is adapted to the interface contour of the top arch of the main transformer chamber, and the bent arc steel bar is fixedly connected to the hook of the temporary bolt to form a support foundation;

[0010] A plurality of the steel pipe limiting holes are fixed on the arc-shaped steel bars according to the preset installation positions of the advanced small pipes and the advanced bolts;

[0011] The advanced small pipes and the advanced bolts pass through the respective steel pipe limiting holes in a one-to-one matching manner and are installed inside the crown arch of the main transformer cavern.

[0012] Preferably, the main transformer cavern is divided into a middle pilot tunnel, a left area and a right area in a horizontally evenly divided manner, and 4-5 temporary bolts are respectively arranged in the middle pilot tunnel, the left area and the right area.

[0013] Preferably, the temporary bolts located in the same area are arranged at equal intervals. The minimum diameter of the temporary bolts is 25 mm, the minimum length is 4.5 m, and the rock penetration depth is at least 4.3 m.

[0014] Preferably, the bending direction of the temporary bolts is perpendicular to the axis direction of the main transformer cavern.

[0015] Preferably, the diameter of the arc-shaped steel bars is at least 28 mm, and the arc-shaped steel bars are fixedly welded to the temporary bolts.

[0016] Preferably, the model of the steel pipe limiting holes is DN50 steel pipes, the wall thickness is 3.8 mm, and the length is at least 5 cm.

[0017] Preferably, the external insertion angle of the advanced small pipes or the advanced bolts is 15° relative to the wall surface of the crown arch of the main transformer cavern.

[0018] Preferably, the spacing between the advanced small pipes or the advanced bolts is 2 m.

[0019] Preferably, the span of the crown arch of the main transformer cavern ≥ 220 m.

[0020] Preferably, the steel pipe limiting holes are fixedly welded to the arc-shaped steel bars.

[0021] The utility model has substantial features and progress compared with the prior art. Specifically, the utility model utilizes the temporary bolts, the arc-shaped steel bars and the steel pipe limiting holes to form the support foundation of the advanced bolts and the advanced small pipes. The temporary bolts, the arc-shaped steel bars and the steel pipe limiting holes rely on the stability of the soil or rock mass of the crown arch, and form a stable support as a whole, replacing the steel arch frame structure required in the traditional tunnel, making it possible for the advanced support means of the combination of the advanced bolts and the advanced small pipes, and further solving the problems of easy block falling or small collapse of the crown arch of the underground powerhouse, and reducing the safety risk of the crown arch of such large-section caverns. Description of the Drawings

[0022] Figure 1 It is a sectional view of the construction of the temporary support bolts in the utility model.

[0023] Figure 2It is a cross-sectional view of the construction of the bent arc steel bar in the utility model.

[0024] Figure 3 It is a cross-sectional view of the construction of the steel pipe limiting hole in the utility model.

[0025] Figure 4 It is a schematic diagram of the principle of the construction of the advanced small guide tube or the advanced anchor rod in the utility model.

[0026] Figure 5 yes Figure 4 Enlarged view of point A in the middle.

[0027] In the figure: 1. Main transformer tunnel top arch; 2. Temporary anchor rod; 3. Bending steel bar; 4. Steel pipe limit hole; 5. Advance small guide tube; 6. Advance anchor rod; 11. Middle guide tunnel; 12. Left area; 13. Right area; 21. Hook. DETAILED DESCRIPTION

[0028] The technical solution of the present utility model is further described in detail below through specific implementation methods.

[0029] like Figures 1 - 5 As shown, an advance support structure for the top arch of an underground powerhouse includes a main transformer tunnel top arch 1, temporary anchor rods 2, curved steel bars 3, steel pipe limiting holes 4, advance small guide tubes 5 and advance anchor rods 6. The span of the main transformer tunnel top arch is usually ≥220m.

[0030] The temporary anchor rods 2 are anchored in the main transformer tunnel top arch 1 at equal intervals. The exposed ends of the temporary anchor rods 2 are close to the main transformer tunnel top arch interface and are provided with hooks 21.

[0031] In this embodiment, the main transformer tunnel 1 is divided into a middle guide tunnel 11, a left area 12 and a right area 13 in a horizontally even manner. 4-5 temporary anchor rods 2 are respectively arranged in the middle guide tunnel 11, the left area 12 and the right area 13. The temporary anchor rods 2 located in the same area are arranged at equal intervals. The minimum diameter of the temporary anchor rod 2 is 25 mm, the shortest length is 4.5 m, and the depth of penetration into the rock is at least 4.3 m. The direction of the hook 21 of the temporary anchor rod is perpendicular to the axial direction of the main transformer tunnel.

[0032] The shape of the curved steel bar 3 is adapted to the interface profile of the main transformer tunnel top arch 1 , and the curved steel bar 3 is welded and fixed to the hook of the temporary anchor rod 2 to form a supporting foundation.

[0033] In this embodiment, the diameter of the curved steel bar 3 is at least 28 mm.

[0034] Several of the steel pipe limiting holes 4 are welded and fixed on the curved steel bar 3 according to the preset installation positions of the advance small guide tube 5 and the advance anchor rod 6;

[0035] The advanced small guide tubes 5 and the advanced anchor rods 6 are matched one by one and pass through each steel pipe limiting hole 4 and are installed inside the main transformer tunnel top arch 1. In this embodiment, the steel pipe limiting hole 4 is a DN50 steel pipe with a wall thickness of 3.8 mm and a length of at least 5 cm.

[0036] The external insertion angle of the said small leading conduit 5 or the leading anchor rod 6 is 15° relative to the main transformer tunnel top arch wall surface, and the spacing between the said small leading conduit or the leading anchor rod is 2m.

[0037] Taking the specific construction process as an example, further explanation is given:

[0038] The first step is to construct 4 to 5 temporary anchor rods near the working face in the underground powerhouse and the main transformer tunnel top arch area (the middle guide tunnel top arch and the top arches on both sides). The temporary anchor rods are arranged in a row with equal intervals. The anchor rod diameter is 25mm, L=4.5m (including the length of the hook), and it is 4.3m deep into the rock. The end of the anchor rod is bent 10cm into a hook that is approximately at a right angle, and the hook is perpendicular to the axis of the tunnel.

[0039] The second step is to process the 28mm diameter steel bars into the same arc as the contour line of the underground powerhouse and the main transformer tunnel top arch area (the middle guide tunnel top arch and the top arches on both sides), and weld the curved steel bars to the temporary anchor hooks firmly.

[0040] In the third step, DN50 steel pipes with a wall thickness of 3.8mm and a length of 5cm for each section are welded on the upper side of the curved steel bars according to the designed spacing of the advance small guide tubes and advance anchor rods, which serve as limit holes for the drilling rig.

[0041] In the fourth step, a rock drill is inserted through the DN50 steel pipe, drilling at an external insertion angle of approximately 15°. Then, a small lead pipe or lead anchor is installed and grouting is performed to complete the advance support. The lead pipe or lead anchor is welded to the DN50 steel pipe and curved rebar to provide support for the top arch rock. The lead pipe or lead anchor is typically spaced 2.0 meters apart, so the temporary anchor and curved rebar spacing is also set at 2.0 meters.

[0042] The fifth step is to carry out excavation after each cycle of advance small guide tubes or advance anchor rods are completed. After each cycle of excavation is completed, subsequent work such as system anchor rods, hanging nets, shotcrete support, and prestressed anchor rods, prestressed anchor cables and other reinforced support shall be carried out in a timely manner.

[0043] This scheme was experimentally validated in the underground powerhouse of the Jiufengshan Pumped Storage Power Station in Huixian County, Henan Province. The total excavation dimensions of the underground powerhouse are 232.2m × 27.0m × 56.5m (length × width × height). The main transformer room and the underground powerhouse are arranged parallel to each other, with a clear distance of 40m between the two tunnels. The main transformer room excavation dimensions are 229.0m × 20.0m × 24.80m. Small faults and alteration zones are present in the area between stakes 0+090 to 0+110 to the right of the main and auxiliary powerhouses and stakes 0+115 to 0+135 to the right of the main transformer tunnel.

[0044] The top arch range of the main and auxiliary powerhouses of Jiufengshan Pumped Storage Power Station, with pile numbers 0+090 to 0+110 on the right side and pile numbers 0+115 to 0+135 on the right side of the main transformer tunnel, was supported by advance grouting of small ducts by adding temporary anchor rods and bent arc steel bars. No landslides occurred, only micro-blocks fell, and the geological over-excavation depth was within 30 cm. This reduced the construction safety risk, accelerated the construction progress, maintained the top arch force structure, and enhanced the stability of the underground cavern.

[0045] Finally, it should be noted that: The above describes in detail the preferred embodiments of this patent, but this patent is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in this field without departing from the purpose of this patent.

Claims

1. An advanced support structure for the top arch of an underground powerhouse, characterized in that: It includes the crown arch of the main transformer cave, temporary anchor bolts, arc-shaped steel bars, steel pipe limit holes, advanced small ducts and advanced anchor bolts; The temporary anchor bolts are anchored in the crown arch of the main transformer cave at equal intervals, and the exposed ends of the temporary anchor bolts are close to the interface of the crown arch of the main transformer cave and are provided with hooks; The shape of the arc-shaped steel bar is adapted to the interface contour of the crown arch of the main transformer cave, and the arc-shaped steel bar is fixedly connected to the hook of the temporary anchor bolt to form a support foundation; A number of the steel pipe limit holes are fixed on the arc-shaped steel bar according to the preset installation positions of the advanced small ducts and the advanced anchor bolts; The advanced small ducts and the advanced anchor bolts pass through the respective steel pipe limit holes in a one-to-one matching manner and are installed inside the crown arch of the main transformer cave.

2. The advanced support structure for the crown arch of the underground powerhouse according to claim 1, wherein: The main transformer cave is divided into a middle guide cave, a left area and a right area in a horizontally evenly divided manner, and 4-5 temporary anchor bolts are respectively arranged in the middle guide cave, the left area and the right area.

3. The advanced support structure for the crown arch of the underground powerhouse according to claim 2, wherein: The temporary anchor bolts in the same area are arranged at equal intervals. The minimum diameter of the temporary anchor bolt is 25 mm, the minimum length is 4.5 m, and the rock penetration depth is at least 4.3 m.

4. The advanced support structure for the crown arch of the underground powerhouse according to claim 3, characterized in that: The hook direction of the temporary anchor bolt is perpendicular to the axis direction of the main transformer cave.

5. The advanced support structure for the crown arch of the underground powerhouse according to claim 4, characterized in that: The diameter of the arc-shaped steel bar is at least 28 mm, and the arc-shaped steel bar is fixedly welded to the temporary anchor bolt.

6. The advanced support structure for the crown arch of the underground powerhouse according to claim 5, characterized in that: The model of the steel pipe limit hole is a DN50 steel pipe, the wall thickness is 3.8 mm, and the length is at least 5 cm.

7. The advanced support structure for the crown arch of the underground powerhouse according to claim 6, wherein: The external insertion angle of the advanced small duct or the advanced anchor bolt is 15° relative to the wall surface of the crown arch of the main transformer cave.

8. The advanced support structure for the crown arch of the underground powerhouse according to claim 1, characterized in that: The spacing of the advanced small ducts or the advanced anchor bolts is 2 m.

9. The advanced support structure for the crown arch of the underground power house according to claim 8, characterized in that: The span of the crown arch of the main transformer cave ≥ 220 m.

10. The advanced support structure for the crown arch of the underground powerhouse according to claim 9, wherein: The steel pipe limit hole is fixedly welded to the arc-shaped steel bar.

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