Large-section cavern arch support structure of underground water-sealed cavern and construction method of large-section cavern arch support structure

Abstract

The invention discloses a large-section cavern arch support structure of an underground water-sealed cavern and a construction method of the large-section cavern arch support structure. The arch frame supporting structure comprises a plurality of structural steel arch frames which are tightly attached to surrounding rock in the length direction of the cavern, arch foot portions of the structural steel arch frames are connected into a whole through horizontally-installed structural steel ground beams, anchor bar piles are arranged between the adjacent structural steel arch frames, one ends of the anchor bar piles are fixedly connected with the structural steel ground beams, and the other ends of the anchor bar piles are fixedly connected with the structural steel ground beams. And the other end is anchored in the cavern surrounding rock. The construction method comprises the following steps: chiseling concrete at arch foot parts of the profile steel arch frames and then mounting the profile steel ground beams; holes are formed in the surrounding rock for mounting of the anchor bar piles, after the holes are formed, the anchor bars and the grouting pipes are welded into a whole to form the anchor bar piles, and after the anchor bar piles are placed in the formed holes, cement mortar is injected to anchor the anchor bar piles in the formed holes; the exposed anchor bar piles are welded and fixed to the profile steel ground beams; and re-spraying concrete to cover the anchor bar piles and the profile steel ground beams. The stability of surrounding rock of the main cavern can be improved, and the safety of the underground water-sealed cavern is guaranteed.

Description

Technical Field

[0001] The invention relates to an underground water-sealed cavern, in particular to a large-section cavern arch support structure of an underground water-sealed cavern and a construction method thereof. Background Art

[0002] Underground water-sealed caverns are mainly built to meet the national oil supply and storage and to respond to emergencies. They are livelihood projects and strategic projects for the development of national energy construction. Underground water-sealed caverns are a type of project that uses artificial excavation to build large caverns in rocks at a certain depth below the stable groundwater level to store oil resources such as crude oil, liquefied petroleum gas and refined oil.

[0003] The main cavern of an underground water-sealed cavern (also called an oil storage cavern) is the main structure for storing oil products and has the following characteristics: (1) Large storage capacity. Generally, the oil storage capacity is 1 million m 3 Up to 10 million m 3 (2) The cross section of the cavern is large. Generally, a straight wall, round arch or curved wall cross section is used, with a span of about 20m and a height of about 30m. (3) The cavern is buried deep. The main cavern is buried deep underground, with a depth of about 100m to 200m. (4) The geological conditions are complex. The main caverns are concentrated and cover an area of ​​about several square kilometers. It is difficult to avoid adverse geological structures and the geological conditions are complex. (5) The stability requirements of the surrounding rock of the cavern are high. The main cavern generally only uses anchor spraying as permanent support, with a designed service life of up to 50 years. It is necessary to ensure the long-term stability and effectiveness of the support structure.

[0004] At present, the construction of four national oil reserves has been completed in China, and the cross-sectional span of the main cavern is about 20m and the height is about 30m. During the construction process, alteration zones, fracture zones and large-scale unstable blocks that affect the stability of the caverns were encountered to varying degrees, which put forward quite high requirements for the stability control of the surrounding rock. With the advancement of national reserve construction and the adjustment of design concepts, more main caverns of the projects currently adopt curved wall sections. In order to ensure the stability of the surrounding rock in the poor geological cave sections, arch support is also adopted. However, due to the influence of the excavation section, the stiffness and integrity of the arch are difficult to deal with.

[0005] The curved wall section is different from the straight wall circular arch section. Since the entire excavation contour line of the curved wall section is composed of several groups of smoothly connected arcs, and its side wall is also a curved wall, from the perspective of force, it can better adapt to poor surrounding rock conditions, has a smaller plastic zone, smaller deformation, and relatively higher safety of the cavern structure. However, when there are large blocks, large-scale alteration zones or broken zones during the cavern excavation process, it is often not enough to rely solely on the self-stability of the cavern surrounding rock, so it is necessary to use a steel arch support with stronger support force.

[0006] When designing the steel arch frame, it is necessary to adapt to the contour of the excavated cavern and provide sufficient rigidity and stability. At the same time, considering that the excavation height of the main cavern is up to 30m, the curved wall section arch frame needs to overcome the problem of insufficient rigidity caused by the large span. The main cavern of the curved wall section is generally designed as follows: Figure 1 The construction is carried out in a layered excavation manner. The stability of the top layer of surrounding rock is the most prominent problem during the excavation process. Figure 1 It can be seen that from the perspective of the second layer h2 excavation height range, the main cavern contour line is an inward-retracting section. Therefore, during the arch erection process, the arch frame also needs to be retracted, which greatly reduces the stiffness of the arch frame and reduces the arch frame supporting force. Summary of the invention

[0007] The technical problem to be solved by the present invention is that, based on the technical difficulties faced by the integrity of the arch frame and the arch foot treatment of the vertical arch section of the main cavern of the underground water-sealed cavern, the present invention provides a large-section cavern arch frame support structure and a construction method for the underground water-sealed cavern, which can improve the stability of the surrounding rock of the main cavern and ensure the safety of the underground water-sealed cavern.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0009] A large-section cavern arch support structure for an underground water-sealed cavern comprises a plurality of steel arches installed close to the surrounding rock along the length direction of the cavern, the arch feet of the plurality of steel arches being connected into a whole by horizontally installed steel ground beams, and anchor piles being arranged between adjacent steel arches, one end of the anchor pile being fixedly connected to the steel ground beam, and the other end being anchored in the surrounding rock of the cavern.

[0010] In order to solve the problem that when a large-span main cavern (with a span of about 20m and a height of about 30m) in an underground water-sealed cavern project passes through an altered zone, a broken zone and a long cave section with unstable blocks in a large range, the steel arch frame is insufficiently rigid due to the large cavern section and has poor overall stability, the present invention adopts a steel ground beam to connect the steel arch frames into a whole, and arranges anchor piles between adjacent steel arch frames, one end of the anchor pile is fixedly connected to the steel ground beam, and the other end is anchored in the cavern surrounding rock, which not only improves the integrity of the steel arch frame in the cavern, but also enhances the supporting force of the arch foot of the arch frame, overcomes the problem of insufficient supporting performance and rigidity of the large-section cavern arch frame in the prior art, improves the stability of the surrounding rock of the large-span main cavern in the poor geological section, and has obvious technical advantages over traditional strong support or section reduction treatment solutions.

[0011] Preferably, the anchor pile comprises a plurality of anchor bars and a grouting pipe made of a seamless steel pipe, and the plurality of anchor bars and the grouting pipe are connected as one body.

[0012] Preferably, the hole diameter of the anchor pile is 100 mm-120 mm.

[0013] Preferably, the hole is filled with cement mortar through the grouting pipe.

[0014] Preferably, a system anchor rod is provided in the surrounding rock, and the steel arch frame is fixedly connected to the system anchor rod.

[0015] Preferably, the steel ground beam is firmly welded to the steel arch frame through angle steel.

[0016] Preferably, the steel arch frame is formed by sequentially splicing a plurality of arch frame segments, and steel pads are reserved at the ends of the arch frame segments.

[0017] Based on the same inventive concept, the present invention also provides a construction method for the large-section cavern arch support structure of the underground water-sealed cavern, which comprises the following steps:

[0018] 1) Excavation of the cavern, identification of geological conditions, and determination of the use of the underground water-sealed cavern large-section cavern arch support structure for construction;

[0019] 2) Install steel arch frame in the cavern;

[0020] 3) Install system anchors and steel mesh in the cavern;

[0021] 4) Shotcrete construction;

[0022] 5) Chisel away the concrete at the arch foot of each steel arch frame and install the steel ground beam;

[0023] 6) Drill holes in the surrounding rock for the installation of anchor piles. After drilling, multiple anchor bars and grouting pipes are welded together to form anchor piles. After the anchor piles are placed in the drilled holes, cement mortar is injected to anchor the anchor piles in the drilled holes.

[0024] 7) Weld and fix the exposed anchor piles to the steel beams;

[0025] 8) Inspection and acceptance;

[0026] 9) Re-spray concrete to cover anchor piles and steel beams;

[0027] 10) Continue excavation of the lower cavern.

[0028] Preferably, the cavern is excavated in layers, and the steel arch frame is installed while excavating.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] ① Technical benefits. The main cavern is the most important structure in the underground water-sealed cavern project, and it is also the structure with the greatest construction risk. How to quickly and efficiently complete the excavation of the cavern with the designed storage capacity is crucial. When encountering large-scale alteration zones, broken zones, and unstable block cave sections, the rigidity of the full-ring arc-shaped steel arch frame is insufficient due to the cross-sectional shape. The present invention uses steel ground beams to connect each steel arch frame into a whole, and sets anchor piles between adjacent steel arch frames. One end of the anchor pile is fixedly connected to the steel ground beam, and the other end is anchored in the cavern surrounding rock. This not only greatly improves the overall stability of the steel arch frame and ensures the safety of large-section caverns under poor geological conditions, but also the present invention has a simple structure, convenient construction, and good molding effect, which supplements the rigid support structure type of large-section main caverns in underground water-sealed caverns.

[0031] ② Economic benefits. Large-scale main cavern groups will inevitably encounter poor geological conditions during construction. By adopting the steel arch anchor pile beam structure of the present invention, it can be quickly and efficiently passed, effectively ensuring the completion of the construction period, while avoiding the huge investment brought by the use of high-strength support. It is an economical, simple and feasible support form.

[0032] ③ Social benefits. The underground water-sealed cavern is a very important strategic project and livelihood project. The main cavern is an important structure for storing oil products. The steel arch anchor pile beam structure of the present invention supplements the main cavern support type and can provide solutions for similar projects. It plays an important supplementary role in the development of the underground water-sealed cavern industry and engineering construction technology. The technology has a broad application prospect and has a significant role and significance in promoting the scientific and technological progress of the industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 This is a typical cross-section diagram of the curved wall main cavern.

[0035] Figure 2 It is a cross-sectional view of the arch support structure of the present invention.

[0036] Figure 3 It is a front view of the arch support structure of the present invention.

[0037] Figure 4 This is the general drawing of the connection between the steel ground beam and the steel arch frame.

[0038] Figure 5This is the cross-sectional drawing of the anchor pile. DETAILED DESCRIPTION

[0039] The present invention is further described below in conjunction with specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

[0040] In the description of the present invention, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0041] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] See also Figure 2 As shown, an embodiment of the arch support structure of the present invention comprises multiple steel arches 1 installed close to the surrounding rock along the length direction of the cavern, and each steel arch 1 is welded to a system anchor arranged in the surrounding rock. The arch foot parts of the multiple steel arches 1 are connected to form a whole through a horizontally installed steel ground beam 2, and anchor piles 3 are arranged between adjacent steel arches 1, one end of the anchor pile 3 is welded to the steel ground beam 2 to form a whole, and the other end is anchored in the surrounding rock of the cavern.

[0043] like Figure 2 As shown, the main component supporting the stability of the surrounding rock is an arc-shaped steel arch frame formed by sequentially splicing multiple arch frame segments of units A to D. It is close to the surrounding rock surface and welded into a whole with the system anchor rods to support the surrounding rock pressure generated by surrounding rock excavation.

[0044] like Figure 3 As shown, the steel beam 2 and the anchor pile 3 are located at the arch foot of the steel arch frame 1. A steel pad 5 is reserved at the end of each arch frame section to facilitate the connection of adjacent arch frame sections.

[0045] like Figure 4As shown, each of the steel beams 2 is firmly welded to the steel arch frame 1 through angle steels 4. The angle of the angle steels 4 is preferably 75 degrees, and the periphery of the angle steels 4 is welded to the steel beams 2 or the steel arch frame 1 to form a whole.

[0046] like Figure 5 As shown, the anchor pile 3 is formed by welding three HRB400 anchor bars 31 with a diameter of 28 mm and a grouting pipe 32 made of a DN28 seamless steel pipe into one piece through spot welding 35. The diameter of the hole 33 of the anchor pile 3 in the surrounding rock is 100 mm-120 mm, preferably 110 mm. The hole 33 is filled with cement mortar 34 through the grouting pipe 32 to anchor the anchor pile 3 in the surrounding rock.

[0047] During the construction of the arch support structure of the present invention, since the main cavern is excavated in layers, the overall stability of the upper cavern needs to be considered during the excavation of the middle and lower layers, so the construction method should also be adapted to the stability control of the surrounding rock of the cavern. The steel arch + anchor pile + steel ground beam structure of the present invention is mainly suitable for cavern sections with large blocks, large-scale alteration zones or broken zones during the excavation process. Its main construction methods and steps are as follows:

[0048] 1) Excavate the cavern, find out the geological conditions, and determine to use the arch support structure of the present invention for support construction;

[0049] 2) Installation of arc-shaped steel arch frame 1;

[0050] 3) Installation of system anchor rods and steel mesh;

[0051] 4) Shotcrete construction;

[0052] 5) Chisel away the concrete at the arch foot of the steel arch frame 1 and install the steel ground beam 2;

[0053] 6) Anchor pile hole making and anchor welding installation: a hole 33 is made in the surrounding rock for the installation of the anchor pile 3. After the hole 33 is made, a plurality of anchor bars 31 and a grouting pipe 32 are welded together to form an anchor pile 3. After the anchor pile 3 is placed in the hole 33, cement mortar 34 is injected to anchor the anchor pile 3 in the hole 33.

[0054] 7) The anchor pile 3 and the steel beam 2 are welded into a whole through the angle steel 4;

[0055] 8) Inspection and acceptance;

[0056] 9) Cover the anchor piles 3 and the steel beam 2 with sprayed concrete;

[0057] 10) Excavation of lower cavern.

[0058] Specific application examples of the present invention:

[0059] Heilongjiang XAL underground water-sealed cavern project is the largest underground water-sealed cavern project under construction in China, with a designed capacity of 6 million cubic meters.

[0060] This project has 14 main caverns, with a single cavern length of about 600m to 930m. The curved wall section is adopted, with a span of 22m and a height of 28m. According to the geological age, genetic lithology and engineering properties, the strata within the elevation range of the main caverns in the reservoir area can be divided into two categories: light gray to light fleshy red medium-coarse grained monzogranite rock group intruded by the Permian; diorite porphyry and granite porphyry in the Mesozoic. The rock mass quality of this project is poor, mainly with grade III and grade IV surrounding rocks, and joints and fissures are developed in the caverns, and many combinations form unstable blocks.

[0061] The scheme of the present invention has been successfully applied in the excavation of the main cavern of this underground water-sealed cavern project, solving the difficult problems of insufficient rigidity and poor overall stability of the main cavern steel arch frame under adverse geological conditions such as large-scale alteration zones, fractured zones and large-scale unstable blocks, ensuring the quality of project construction and controllable construction period and investment. At the same time, it has significant benefits in improving the technical reserves of the underground water-sealed cavern industry and promoting the development of the industry.

[0062] The above is only a specific implementation scheme of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the art can make many possible changes and modifications to the technical scheme of the present invention by using the technical content disclosed above without departing from the scope of the technical scheme of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical scheme of the present invention should fall within the protection scope of the technical scheme of the present invention.

Claims

1. A large-section cavern arch support structure for underground water-sealed caverns, comprising a plurality of steel arches installed close to the surrounding rock along the length of the cavern, characterized in that: The arch foot parts of the multiple steel arch frames are connected into a whole through horizontally installed steel ground beams, and anchor piles are arranged between adjacent steel arch frames. One end of the anchor pile is fixedly connected to the steel ground beam, and the other end is anchored in the surrounding rock of the cavern.

2. According to claim 1, the large-section cavern arch support structure of underground water-sealed cavern is characterized in that: The anchor pile comprises a plurality of anchor bars and a grouting pipe made of a seamless steel pipe, and the plurality of anchor bars and the grouting pipe are connected as a whole.

3. The large-section cavern arch support structure of underground water-sealed cavern according to claim 2 is characterized in that: The hole diameter of the anchor pile is 100mm-120mm.

4. The large-section cavern arch support structure of underground water-sealed cavern according to claim 3 is characterized in that: The hole is filled with cement mortar through the grouting pipe.

5. The large-section cavern arch support structure of underground water-sealed cavern according to claim 1 is characterized in that: A system anchor rod is arranged in the surrounding rock, and the steel arch frame is fixedly connected to the system anchor rod.

6. The large-section cavern arch support structure of underground water-sealed cavern according to claim 1 is characterized in that: The steel ground beam is firmly welded to the steel arch frame through angle steel.

7. The large-section cavern arch support structure of underground water-sealed cavern according to claim 1 is characterized in that: The steel arch frame is formed by sequentially splicing a plurality of arch frame segments, and steel pads are reserved at the ends of the arch frame segments.

8. A construction method for a large-section cavern arch support structure of an underground water-sealed cavern as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: 1) Excavation of the cavern, ascertaining the geological conditions, and determining to adopt the large-section cavern arch support structure of the underground water-sealed cavern as described in any one of claims 1 to 7 for construction; 2) Install steel arch frame in the cavern; 3) Install system anchors and steel mesh in the cavern; 4) Shotcrete construction; 5) Chisel away the concrete at the arch foot of each steel arch frame and install the steel ground beam; 6) Drill holes in the surrounding rock for the installation of anchor piles. After drilling the holes, weld multiple anchor bars and grouting pipes into one to form anchor piles. After placing the anchor piles in the drilled holes, inject cement mortar to anchor the anchor piles in the drilled holes. 7) Weld and fix the exposed anchor piles to the steel beams; 8) Inspection and acceptance; 9) Re-spray concrete to cover anchor piles and steel beams; 10) Continue excavation of the lower cavern.

9. The construction method of the large-section cavern arch support structure of the underground water-sealed cavern according to claim 8 is characterized in that: The cavern is excavated in layers, and the steel arch frame is installed while excavating.

Images