An underground water-sealed storage cavern alteration zone hole section excavation and support method

Abstract

The application discloses a kind of underground water seal cave chamber alteration zone hole section excavation support methods, which is set in the alteration zone hole section of main cavern along the axis direction of main cavern Strengthened support range;The upper layer of main cavern in strengthened support range adopts normal section excavation and uses first type steel arch support;The middle layer to bottom layer of main cavern in strengthened support range adopts shrink section excavation mode, i.e. in the middle layer to bottom layer of main cavern, slope is used to dig down in slope, the included angle between the slope and the bottom plate of main cavern is acute angle α, and the middle layer to bottom layer of main cavern forms inclined rock column for supporting alteration zone;A certain width of edging beam is arranged on the top of the slope on both sides of main cavern, to provide support for the first type steel arch of upper layer;Along the axis direction of cavern, a plurality of second type steel arch supports are installed on the slope on both sides of main cavern, and a plurality of groups of steel arch rib reinforced supports are arranged on the slope along the axis direction of cavern, and steel strips are used to connect between steel arch ribs of each group of steel arch rib.

Description

Technical Field

[0001] This invention relates to underground water-sealed caverns, specifically to a method for excavation and support of cavern sections in the erosion zone of underground water-sealed caverns. Background Technology

[0002] Water-sealed underground caverns are a primary method of oil storage. The principle behind these projects is to excavate a cavern of a certain volume into the underground rock at a depth below the stable groundwater level, using the water seal effect of the stable groundwater to seal and store the oil within. The underground structures, serving as the main components of the oil storage, primarily consist of storage tanks, process shafts, ventilation shafts, water curtain tunnels, and construction tunnels, all buried deep underground.

[0003] The site selection for underground water-sealed caverns is usually in areas with good surrounding rock conditions and high permeability to ensure the safety and water-sealing properties of the caverns. However, due to the large layout of the caverns and the influence of the arrangement of oil storage tanks, large-scale alteration zones may appear in some areas. The surrounding rock in these areas is low in strength and relatively fractured, making conventional large-section excavation and support methods difficult to construct, requiring high support strength, and posing a high risk of collapse. Summary of the Invention

[0004] The technical problem to be solved by this invention is to address the issue of surrounding rock stability in large-section main caverns of underground water-sealed caverns when traversing large-scale alteration zones. This invention provides an excavation and support method for alteration zones of underground water-sealed caverns that, compared to normal large-section excavation and support methods, can significantly improve the stability of surrounding rock in large-scale alteration zone sections, reduce construction difficulty, and ensure construction safety.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A method for excavation and support of an altered section of an underground water-sealed cavern, characterized by the following structural features:

[0007] A reinforced support area is set along the axis of the main cavern in the altered zone section;

[0008] The upper part of the main tunnel within the reinforced support area shall be excavated with a normal cross section and supported by a first type of steel arch frame;

[0009] The main cavern from the middle to the bottom layer within the reinforced support area adopts a reduced cross-section excavation method, that is, the main cavern from the middle to the bottom layer adopts a slope excavation method, the angle between the slope and the bottom plate of the main cavern is an acute angle α, and the middle to the bottom layer of the main cavern forms an inclined rock column to support the alteration zone.

[0010] A certain width of edging beam is set at the top of the slope on both sides of the main cavern to provide support for the first type of steel arch frame on the upper level;

[0011] Multiple second-type steel arch frames are installed on the slopes on both sides of the main cavern along the cavern axis, and multiple sets of steel arch ribs are arranged at intervals on the slopes along the cavern axis to reinforce the support. The steel arch ribs of each set of steel arch ribs are connected by steel strips.

[0012] Thus, when the main tunnel passes through a large-scale alteration zone, due to the poor geological conditions, the present invention adopts the above-mentioned innovative main tunnel excavation and support method (upper layer normal cross-section excavation and support + middle, lower and bottom layer narrow cross-section excavation and reinforced support), which reduces the construction difficulty of the alteration zone section, greatly improves the stability of the surrounding rock of the alteration zone, and ensures the safety of underground tunnel excavation. It has obvious technical advantages compared with the normal large cross-section excavation and support method.

[0013] Preferably, the reinforced support range includes an alteration zone range and an extension section and a gradient section arranged sequentially on both sides of the alteration zone range. The extension section is smoothly connected to the alteration zone range, and the width of the edging beam and the width of the bottom surface of the inclined rock column of the gradient section gradually decreases towards both sides of the reinforced support range.

[0014] Preferably, a vehicle passage is provided at the bottom of the main tunnel along the tunnel axis within the reinforced support area.

[0015] Preferably, the second type of steel arch frame and the steel arch rib are fixed by anchor bolts, and the anchor bolts are prestressed expansion shell type hollow grouting anchor bolts and / or ordinary mortar anchor bolts.

[0016] Preferably, the prestressed expansion shell hollow grouting anchor rod and the ordinary mortar anchor rod are arranged at intervals.

[0017] Preferably, the construction sequence of the main tunnel support method from the middle to the bottom layer is as follows: hanging steel mesh - second type steel arch support - steel arch rib support - shotcrete - anchor support - edge beam construction.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] ① In terms of technical benefits: When the main tunnel passes through a large-scale alteration zone, the conventional large-section excavation method carries a high risk of collapse. This invention adopts a method of pre-reserving inclined rock pillars through sloping excavation and strengthening the support, which significantly improves the stability of the surrounding rock in the alteration zone section and solves the problem of high safety risks under large-section excavation in the alteration zone section. At the same time, the support is strengthened by using steel arch frames and steel arch ribs. This support method is simpler to construct than steel grid beams and has a better forming effect.

[0020] ② In terms of social benefits: Underground water-sealed caverns, as a primary form of energy storage, possess advantages such as strong concealment, safety, reliability, economy, and environmental friendliness, making them a vital public welfare project. The main cavern is the primary oil storage structure, and its safety and stability are crucial indicators for ensuring oil storage capacity. This invention can provide solutions for similar projects and plays a significant supplementary role in the development of the underground water-sealed cavern industry and its engineering construction technology. This technology has broad application prospects and plays a significant role in promoting technological progress in the industry. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the excavation and support structure for the altered zone section of the main tunnel in this invention.

[0023] Figure 2 Plan view of the treatment of the alteration zone section of the main cavern.

[0024] Figure 3 Plan layout of anchor bolt support in the lower layer of the main tunnel section in the alteration zone.

[0025] In the picture:

[0026] D1 - Width of the edging beam; D2 - Width of the inclined rock column; D3 - Width of the vehicle passageway; α - Angle between the outer surface of the inclined rock column and the surface of the base plate;

[0027] H - Height of the inclined rock column; H1 - Upper layer excavation height; H2 - Middle to upper layer excavation height; H3 - Middle to lower layer excavation height; H4 - Lower layer excavation height; H5 - Bottom layer excavation height;

[0028] L1 - Alteration zone range; L - Reinforced support range;

[0029] B1 - Distance between the steel arch ribs and the edging beams; B2 - Spacing between the steel arch ribs; B3 - Spacing between the second type of steel arch frames;

[0030] 1 – Type I steel arch frame; 2 – Slope; 3 – Main chamber floor slab; 4 – Inclined rock column; 5 – Edge beam; 6 – Vehicle passageway; 7 – Type II steel arch frame; 8 – Reinforced arch rib; 9 – Steel strip; 10 – Prestressed expansion shell hollow grouting anchor; 11 – Ordinary mortar anchor; 12 – Normal cross-section of the main chamber. Detailed Implementation

[0031] The present invention will be further described below with reference to specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0032] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0033] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0034] Please see Figure 1 - Figure 3 An embodiment of the method for excavation and support of the altered zone section of the underground water-sealed cavern of the present invention is implemented according to the following scheme.

[0035] 1) Excavation plan

[0036] When the main tunnel traverses a large-scale alteration zone, the surrounding rock is weak and fragmented, consisting mostly of extremely soft rock. Conventional large-section excavation methods are insufficient to ensure rock stability, posing a high safety risk and making collapse highly probable. To ensure the structural stability of the main tunnel, such as... Figure 1 As shown, the upper layer of the main tunnel is excavated with a normal cross-section and supported by a first-type steel arch frame 1. From the middle to upper layers of the main tunnel, a reduced cross-section treatment is adopted, i.e., sloping excavation is carried out. The angle between this slope 2 and the main tunnel floor 3 is α. Inclined rock pillars 4 are formed on both sides of the main tunnel to support the large-scale alteration zones on both sides. The height of the inclined rock pillars 4 is H, and the bottom width is D2. Simultaneously, a edging beam 5 of a certain width, D1, is installed at the top of the slope 2 to support the first-type steel arch frame 1 on the upper layer, ensuring the stability of the foundation of the first-type steel arch frame 1. Furthermore, to ensure convenient traffic access to the main tunnel after the lower layer is excavated, a vehicle passage 6 with a width of D3 is provided at the lower layer to meet the traffic needs of drilling, blasting, and muck removal.

[0037] like Figure 2As shown, the reinforced support range L of the alteration zone section along the axis of the main cavern is determined according to the actual length L1 of the alteration zone range. Variable cross-section extension sections and gradual transition sections are set sequentially at both ends of the alteration zone range to ensure smooth connection with the normal cross-section 12 of the main cavern.

[0038] Under this excavation scheme, by excavating down the slope and reserving inclined rock pillars, the stability of the surrounding rock in the altered zone tunnel section is greatly improved, meeting the safety requirements of the structure.

[0039] 2) Support scheme

[0040] To ensure the stability of the surrounding rock in the large-scale alteration zone of the main cavern during construction and operation, a strong support scheme was implemented for the alteration zone section. This was combined with the actual conditions of the underground water-sealed cavern project, such as... Figure 3 As shown, the inclined rock column 4 is supported by multiple second-type steel arch frames 7 arranged along the tunnel axis, with a spacing of B3 between the second-type steel arch frames. Simultaneously, multiple sets of reinforced steel arch ribs 8 are arranged along the tunnel axis to reinforce the support, with a spacing of B2 between adjacent sets of reinforced steel arch ribs. The spacing between the reinforced steel arch ribs and the edge beam at the top of the inclined rock column is B1. Steel strips 9 are arranged between the reinforced steel arch ribs within the same set to ensure the integrity of the reinforced steel arch rib group. The second-type steel arch frames 7, reinforced steel arch ribs 8, and steel strips 9 are fixed with anchor bolts. The anchor bolts are prestressed expansion shell hollow grouting anchor bolts 10 and ordinary mortar anchor bolts 11, arranged alternately. The construction sequence of the various support methods for the inclined rock column 4 is as follows: hanging steel mesh, second-type steel arch frame support, reinforced steel arch rib support, shotcrete, anchor bolt support, and edge beam construction.

[0041] Compared with the traditional steel grid beam support method for slopes, the support method of this invention is convenient and simple to construct, reducing the construction difficulty. At the same time, the surface of the main tunnel after completion is flat and has a good visual effect, ensuring the support strength of the tunnel section in the altered zone and greatly improving the stability of the surrounding rock.

[0042] The following describes specific application examples of the present invention.

[0043] The Heilongjiang XAL underground water-sealed cavern project is currently the largest underground water-sealed cavern project under construction in China, with a designed capacity of 6 million cubic meters.

[0044] During the excavation of the upper and middle layers of a main tunnel, a large-scale alteration zone approximately 15m wide was traversed. The rock in this alteration zone section is argillaceous, with low uniaxial saturated compressive strength and low shear strength of the structural surfaces. The main tunnel's cross-section is 22.0m × 28.0m, and the upper layer has been excavated to a height of 9.0m. If conventional large-section excavation methods are used, the risk of collapse of the surrounding rock on both sides is high. This invention's proposed method for treating the large-scale alteration zone in the main tunnel section was applied, employing a reduced cross-section and a sloping excavation method. The width of the inclined rock pillars on both sides is 5.97m, and the height is 19.0m, with an angle of 72° between the outer surface of the inclined rock pillars and the bottom slab. A 7.0m wide passageway was reserved in the middle and lower layers to ensure the passage of muck removal vehicles and equipment vehicles, and the width of the edging beam is 1.6m. These inclined rock pillars effectively support the alteration zones on both sides and the first type of steel arch frame in the upper layer, improving structural stability.

[0045] For the inclined rock column, I20b type II steel arch frames are arranged at 1.0m intervals along the tunnel axis for support, and multiple sets of 4C28 steel arch ribs are arranged at 2.0m intervals along the tunnel axis for support. Fixed anchor bolts are reinforced by alternating arrangements of φ32 prestressed expansion shell hollow grouting anchor bolts with a row spacing of 2.0m and L=15.0m and C25 ordinary hollow grouting anchor bolts with a row spacing of 1.0m and L=6.0m. This support method is simpler to construct than reinforced lattice beams and produces better results.

[0046] The successful application of this invention has solved the problems of poor surrounding rock stability, high construction difficulty, and high safety risks caused by poor geological conditions in large-span main caverns due to large-scale alteration zones. It has significantly improved the stability of the surrounding rock, made construction simpler, ensured the quality of the project construction, guaranteed the construction period and controllable investment, and has significant implications for improving the technical reserves of the underground water-sealed cavern industry and promoting the industry's development.

[0047] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can make many possible variations and modifications to the technical solution of the present invention, or modify it into equivalent embodiments with equivalent changes, without departing from the scope of the technical solution of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention should fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for supporting the excavation of a cavern section of an altered zone of a groundwater-sealed cavern, the cavern section of the altered zone referring to a large-span main cavern passing through a large-scale altered zone, characterized in that: a reinforced support range is arranged along the axis direction of the main cavern at the cavern section of the altered zone of the main cavern; the upper layer of the main cavern in the reinforced support range is excavated with a normal section and supported by a first type of steel arch; the middle layer to the bottom layer of the main cavern in the reinforced support range is excavated with a reduced section, i.e. the middle layer to the bottom layer of the main cavern is excavated by a slope-dumping method, the slope has an acute angle α with the bottom plate of the main cavern, and the middle layer to the bottom layer of the main cavern forms an inclined rock column for supporting the altered zone; an edge beam with a certain width is arranged on the top of the slope on both sides of the main cavern to provide support for the first type of steel arch of the upper layer; a plurality of second type of steel arch supports are installed along the axis direction of the cavern on the slope on both sides of the main cavern, and a plurality of groups of steel arch rib reinforcement supports are arranged along the axis direction of the cavern at intervals on the slope, the steel arch ribs of each group of steel arch rib reinforcement supports are connected by steel strips, and the second type of steel arch and the steel arch rib are fixed by anchor rods; the construction sequence of the support method for the middle layer to the bottom layer of the main cavern is: hanging steel mesh, second type of steel arch support, steel arch rib support, spraying concrete, anchor rod support, and edge beam construction. The reinforced support range includes the altered zone range and an extension section and a gradual change section arranged on both sides of the altered zone range in sequence, the extension section is smoothly connected with the altered zone range, and the width of the edge beam and the width of the bottom surface of the inclined rock column of the gradual change section gradually decrease towards both sides of the reinforced support range. A vehicle passage is arranged at the bottom of the reinforced support range along the axis direction of the cavern. The anchor rod is fixed by a prestressed inflatable shell type hollow grouting anchor rod and / or a common mortar anchor rod. The prestressed inflatable shell type hollow grouting anchor rod and the common mortar anchor rod are arranged at intervals. ​ ​ 2. The underground water-sealed storage cavern excavation and support method of claim 1, wherein, ​ 3. The underground water-sealed storage cavern excavation and support method of claim 1, wherein, ​ 4. The method of claim 1, wherein the method further comprises: ​ 5. The underground water-sealed storage cavern excavation and support method of claim 4, wherein, ​

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