An underground water-sealed storage shaft sealing plug and a parameter determination method thereof

Abstract

The application provides a groundwater sealed cave vertical shaft sealing plug and a parameter determination method thereof. The sealing plug comprises an integral main column and no less than two annular protrusions. The protrusions are circumscribed on the outer circumference of the main column and extend radially outward along the main column. The cross section of the protrusions along the length direction of the main column is triangular. The sealing plug adopts the form of the main column combined with the annular protrusions, which increases the combined surface of the sealing plug and the vertical shaft, significantly improves the bearing capacity of the sealing plug, and at the same time, only the protrusions need to be excavated again during the construction in the vertical shaft, the engineering quantity is small, the construction is convenient, the forming effect of the sealing plug is good, and the increased concrete quantity is small. The parameter determination method provided by the application can determine the sealing plug parameters to provide suitable bearing capacity according to the specific vertical shaft.

Description

Technical Field

[0001] This invention belongs to the field of underground water-sealed caverns, specifically relating to a sealing plug for a vertical shaft of an underground water-sealed cavern and a method for determining its parameters. Background Technology

[0002] A water-sealed underground oil cavern is a large complex of caverns constructed by excavation at a certain depth below the stable groundwater level to store petroleum resources such as crude oil, liquefied petroleum gas, and refined oil products. It mainly consists of a main cavern complex, connecting tunnels, construction tunnels, ventilation shafts, and process shafts.

[0003] Process shafts connect the surface to underground oil storage chambers and serve as channels for oil entry and exit. After construction, the shafts must be sealed with plugs to isolate the oil from the external environment, forming an independent, sealed storage space. The plugs are typically located at the bottom of the shaft, near the top arch of the storage chamber. Suspended in the shaft, these plugs must bear the load of approximately 100 meters of process piping above, the backfill bentonite, and the filling water. They are characterized by their long burial depth and large upper load; research indicates that the load on the plugs can reach 3000-5000 tons. Therefore, the structural stability of the plugs is crucial for the safe operation of the project. During the design phase, process shafts and plugs are generally placed in areas with favorable geological conditions and good surrounding rock properties. However, due to the overall project layout, the plug section inevitably has unfavorable structures such as alteration zones and fracture zones, making conventional plugs insufficient to meet the load-bearing requirements. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a sealing plug for a vertical shaft of an underground water-sealed cavern and a method for determining its parameters, which has the advantage of high bearing capacity and can adapt to various geological conditions, especially weak surrounding rock conditions.

[0005] The present invention discloses a sealing plug for a vertical shaft of an underground water-sealed cavern, comprising an integrally formed main column and at least two annular protrusions. The protrusions are externally connected to the outer circumference of the main column and extend radially outward along the main column. The cross-section of the protrusions along the length of the main column is triangular.

[0006] The sealing plug satisfies the following formula:

[0007] ;

[0008] In the formula: γ0 is the structural importance coefficient; G1 is the design condition factor; G2 is the self-weight of the sealing plug; G3 is the self-weight of the backfill bentonite; F is the self-weight of the filling water; θ is the process piping load; i Let θ be the angle between the lower side wall of the i-th protrusion from top to bottom and the vertical, where i is 1, 2, ..., n, n≥2; nis the vertical angle between the nth convex lower sidewall and the vertical; γ d is the basic combination structure coefficient; f R is the shear fracture friction coefficient of the concrete and bedrock contact surface; G i is the self weight of the partial sealing plug up to the ith convex lower sidewall, C R is the shear fracture cohesion of the concrete and bedrock contact surface; λ is the contact surface effective area coefficient; A is the side surface area of the sealing plug and the shaft bedrock surface contact;

[0009] From top to bottom, the upper edge of the first convex is flush with the upper edge of the column, and the lower edge of the last convex is flush with the lower edge of the column.

[0010] The sealing plug adopts the form of a main column combined with a plurality of annular convexes, which increases the combined surface of the sealing plug and the shaft, significantly improves the carrying capacity of the sealing plug, and at the same time, only needs to excavate the convexes again during construction in the shaft, has small engineering quantity and convenient construction, has good forming effect of the sealing plug, and has small added concrete quantity.

[0011] Further, the ring width of the convex is 1.0m-2.0m to ensure the carrying strength of the convex.

[0012] Further, from top to bottom, the ring width of the convex is sequentially increased to further improve the carrying capacity of the sealing plug.

[0013] Further, from top to bottom, the height of the convex is sequentially increased to further improve the carrying capacity of the sealing plug.

[0014] Further, it further comprises a first column, and the lower end of the first column and the upper end of the main column are connected as one body. Increasing the first column at the upper end of the main column of the sealing plug can improve the anchoring force of the process pipeline and the sealing plug concrete structure, and reduce the stress concentration phenomenon at the angle combination of the first convex at the uppermost edge and the main column.

[0015] Further, the height of the first column is 0.5m-1.0m to ensure smooth stress transition.

[0016] Further, it further comprises a second column, and the upper end of the second column and the lower end of the main column are connected as one body. Similarly, increasing the second column at the lower end of the main column of the sealing plug can improve the anchoring force of the process pipeline and the sealing plug concrete structure, and reduce the stress concentration phenomenon at the angle combination of the last convex at the lowermost edge and the main column.

[0017] Further, the height of the second column is 0.5m-1.0m to ensure smooth stress transition.

[0018] Another aspect of the present application also provides a method for determining parameters of a sealing plug of a vertical shaft of a groundwater-sealed cavern, which is used for determining the shape size parameters of the sealing plug of the vertical shaft of the groundwater-sealed cavern, and comprises the following steps:

[0019] S1, calculating the self-weight of backfill bentonite G2, the self-weight of filling water G3 and the load of process pipeline F;

[0020] S2, determining the position of the sealing plug in the vertical shaft and the shear friction coefficient f of the contact surface between concrete and bedrock R and the shear cohesion C of the contact surface between concrete and bedrock R ;

[0021] S3, determining the shape size parameters H, d0, di, h i-1 , h i-2 , θ i , Hi of the sealing plug; H is the total height of the sealing plug, d0 is the diameter of the main column, di is the ring width of the i-th protrusion from top to bottom, h i-1 is the height of the upper side wall of the i-th protrusion, h i-2 is the height of the lower side wall of the i-th protrusion, θ i is the vertical angle of the lower side wall of the i-th protrusion from top to bottom, i is 1, 2, … n, and n≥2; Hi is the height of the part of the sealing plug up to the lower side wall of the i-th protrusion; and calculating the self-weight G1 of the sealing plug;

[0022] S4, calculating the action effect function S(.) and the anti-sliding stability resistance function R(.), of the sealing plug, , ; θ n is the vertical angle of the lower side wall of the n-th protrusion; G i is the self-weight of the part of the sealing plug up to the lower side wall of the i-th protrusion; θ i is the vertical angle of the lower side wall of the i-th protrusion from top to bottom, i is 1, 2, … n, and n≥2; λ is the effective area coefficient of the contact surface; and A is the lateral surface area of the contact between the sealing plug and the bedrock surface of the vertical shaft;

[0023] S5, if the following condition is met, , γ0 is the structure importance coefficient; is the design condition coefficient; γ d is the basic combination structure coefficient;

[0024] that is: , the design is completed, otherwise, go to S3.

[0025] Further, the S3 further comprises determining the height h1 of the first column and / or determining the height h2 of the second column.

[0026] The present application has the following beneficial effects:

[0027] 1) The sealing plug designed in the present application comprises a plurality of annular protrusions, thereby having multiple bedrock contact surfaces and being capable of providing higher bearing capacity. When the construction encounters unfavorable geological bodies such as alteration zones and broken zones and the overall layout is limited and cannot be adjusted, the sealing plug can be applied to the sealing of underground oil storage caverns in process shafts, thereby avoiding problems such as high engineering cost, great difficulty and long demonstration period caused by adjusting the position of the process shaft.

[0028] 2) The sealing plug designed in the present application has the advantages of small secondary excavation volume, small increase in concrete volume, convenient construction and small increase in construction period, and is greatly beneficial to engineering investment control and construction period guarantee. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a sectional view of the sealing plug of the underground water-sealed cavern shaft provided by some embodiments of the present application,

[0030] Figure 2 is a sectional view of the sealing plug of the underground water-sealed cavern shaft provided by some embodiments of the present application,

[0031] Figure 3 is a sectional view of the sealing plug of the underground water-sealed cavern shaft provided by some embodiments of the present application,

[0032] Figure 4 is a radial sectional view of the sealing plug of the underground water-sealed cavern shaft provided by some embodiments of the present application, a is the cross section of the main column, b is the cross section of the ring width of the first protrusion, and c is the cross section of the ring width of the second protrusion,

[0033] Figure 5 is a flow chart of the parameter determination method of the sealing plug of the underground water-sealed cavern shaft provided by some embodiments of the present application;

[0034] Figure 6 is a sectional view of the sealing plug of the underground water-sealed cavern shaft provided by some embodiments of the present application, and the length unit in the figure is mm;

[0035] EXPLANATION OF REFERENCE NUMBERS

[0036] 00 main column, 01 first protrusion, 02 second protrusion, 11 first column, and 22 second column;

[0037] d0 diameter of the main column, d1 ring width of the first protrusion, D1 outer diameter of the first protrusion, d2 ring width of the second protrusion, D2 outer diameter of the second protrusion, h1 height of the first column, h1-1 height of the upper side wall of the first protrusion, h1-2 height of the lower side wall of the first protrusion, h2-1 height of the upper side wall of the second protrusion, h2-2 height of the lower side wall of the second protrusion, h1 height of the second column, H1 height of the part of the sealing plug from the top to the lower side wall of the first protrusion, H2 height of the part of the sealing plug from the top to the lower side wall of the second protrusion, and H total height of the sealing plug. Detailed Implementation

[0038] To more clearly and completely describe the technical solution of the present invention, the present invention will be further described in detail below through specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. Various changes can be made within the scope of the claims of the present invention.

[0039] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "vertical," "horizontal," "left," "right," and similar expressions are for illustrative purposes only and do not represent the only possible implementation. The term "and / or" includes any and all combinations of one or more of the associated listed items. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0040] like Figure 1 As shown, in one embodiment of the present invention, the sealing plug for the underground water-sealed cavern shaft includes an integrally formed main column 00 and at least two annular protrusions. The protrusions are externally connected to the outer circumference of the main column 00 and extend radially outward along the main column 00. The cross-section of the protrusion along the length of the main column is triangular. The annular width of the protrusion is 1.0m-2.0m. From top to bottom, the upper edge of the first protrusion is flush with the upper edge of the column, and the lower edge of the last protrusion is flush with the lower edge of the column. The protrusions are named from top to bottom as Protrusion 1, Protrusion 2, and so on until the last protrusion. For example, there are n protrusions, where n is 4. From top to bottom, the first protrusion is Protrusion 1, the second protrusion is Protrusion 2, the third protrusion is Protrusion 3, and the nth protrusion, i.e., the fourth protrusion, is Protrusion 4. Optionally, from top to bottom, the annular width of the protrusions increases sequentially; from top to bottom, the height of the protrusions increases sequentially.

[0041] like Figure 4 As shown, the outer diameters of the main column, protrusion one, and protrusion two increase sequentially.

[0042] like Figure 2 As shown, in another embodiment of the present invention, the sealing plug for the underground water-sealed cavern shaft further includes a first column 11, the lower end of which is integrally connected to the upper end of the main column 00. The height of the first column 11 is 0.5m-1.0m.

[0043] like Figure 3As shown, the present application provides another embodiment of the underground water-sealed cave vertical shaft sealing plug, which comprises a second column 22 in addition to the first column 11, and the upper end of the second column 22 is connected to the lower end of the main column 00 as a whole. The height of the second column 22 is 0.5m-1.0m.

[0044] As shown, the present application determines the shape size parameters of the above-mentioned underground water-sealed cave vertical shaft sealing plug, which comprises the following steps: Figure 5

[0045] S1, calculate the self-weight of backfill bentonite G2, the self-weight of filling water G3, and the process pipeline load F;

[0046] S2, determine the position of the sealing plug in the vertical shaft and the shear friction coefficient f of the concrete and bedrock contact surface R and the shear cohesion C of the concrete and bedrock contact surface R ;

[0047] S3, determine the shape size parameters H, d0, di, h i-1 , h i-2 , θ i , Hi of the sealing plug; H is the total height of the sealing plug, d0 is the diameter of the main column 00, di is the ring width of the i-th protrusion from top to bottom, h i-1 is the height of the upper side wall of the i-th protrusion, h i-2 is the height of the lower side wall of the i-th protrusion, θ i is the vertical angle of the lower side wall of the i-th protrusion from top to bottom, i is 1, 2, … n, n≥2; Hi is the height of the part of the sealing plug to the lower side wall of the i-th protrusion; and calculate the self-weight G1 of the sealing plug;

[0048] S4, calculate the action effect function S(.) and the anti-sliding stability resistance function R(.), of the sealing plug, , ; θ n is the vertical angle of the lower side wall of the n-th protrusion; G i is the self-weight of the part of the sealing plug to the lower side wall of the i-th protrusion; θ i is the vertical angle of the lower side wall of the i-th protrusion from top to bottom, i is 1, 2, … n, n≥2; λ is the effective area coefficient of the contact surface; A is the side surface area of the sealing plug in contact with the bedrock surface of the vertical shaft;

[0049] S5, if , γ0 is the structure importance coefficient; is the design condition coefficient; γ d is the basic combination structure coefficient;

[0050] that is: , the design is completed, otherwise go to S3. ​

[0051] In one of the embodiments, S3 further comprises determining the height h1 of the first column 11; in another of the embodiments, S3 further comprises determining the height h1 of the first column 11 and determining the height h2 of the second column 11.

[0052] Embodiment

[0053] Taking a groundwater sealed cavern project in a certain place in China as an example, eight process shafts are arranged in the project, the process shafts have a depth of about 140.0 m, are divided into oil inlet shafts and oil outlet shafts, the oil inlet shafts have a net diameter of 5.0 m and are arranged with oil inlet pipelines; the oil outlet shafts have a net diameter of 6.0 m and are arranged with oil outlet pipelines, other process pipelines, instruments, cables and their casings and the like. In order to ensure the safety and water sealing of the oil storage space, one sealing plug is arranged at a depth of about 125.0 m at the bottom of each process shaft. In the excavation process, the sealing plug sections of five process shafts are exposed to different degrees of alteration zone, the alteration zone has low shear strength, taking the oil inlet shaft as an example, the shaft has a diameter of 5.3 m, the original design adopts a single key groove sealing plug of grade III surrounding rock, and the bearing capacity cannot meet the requirements.

[0054] The sealing plug provided by the present application is used instead, the sealing plug has a size as shown in Figure 6 The shear fracture friction coefficient f R of the concrete and the bedrock contact surface is 0.7; the shear fracture cohesion C R of the concrete and the bedrock contact surface is 0.3 MPa; the self weight G1 of the concrete sealing plug is 6195 kN; the self weight G2 of the backfill bentonite is 3240 kN; the self weight G3 of the filling water is 21206 kN; the process pipeline load F is 1000 kN; the effective area coefficient λ of the contact surface is taken as 0.5 for the straight wall section, 0 for the upper side wall of the protrusion and 1.0 for the lower side wall of the protrusion; the structure safety level is divided into grade I, grade II and grade III, and the structure importance coefficient γ0 is taken as 1.1, 1.05 and 1.0 respectively; in the present embodiment, 1.1 is taken. According to the permanent design condition, the short-term design condition and the accidental design condition, the design condition coefficient is taken as 1.0, 0.95 and 0.85 respectively; in the present embodiment, 1.0 is taken. The sealing plug structure is calculated by using the anti-sliding stability limit state design, and the basic combination structure coefficient γ d of the specification is taken as 1.5. Through calculation, the anti-sliding stability resistance function of the sealing plug provided by the present application is 36807 kN, which is increased by 76.5% compared with the anti-sliding stability resistance function 20850 kN of the original design of the single key groove sealing plug of grade III surrounding rock.

[0055] At the same time, the following is obtained through calculation:

[0056] ,

[0057] ,

[0058] satisfy the formula:

[0059] .

[0060] wherein: γ0 is a structure importance coefficient; is a design condition coefficient; G1 is the self-weight of the sealing plug; G2 is the self-weight of the backfill bentonite; G3 is the self-weight of the filling water; F is a process pipeline load; θ i is an angle between the ith protrusion lower side wall and the vertical direction from top to bottom, i is 1, 2, …n, and n≥2; θ n is an angle between the nth protrusion lower side wall and the vertical direction; γ d is a basic combination structure coefficient; f R is a shear friction coefficient of the concrete and the bedrock contact surface; G i is a partial self-weight of the sealing plug up to the ith protrusion lower side wall, C R is a shear cohesion of the concrete and the bedrock contact surface; λ is an effective area coefficient of the contact surface; and A is a side surface area of the sealing plug in contact with the shaft bedrock surface.

[0061] The sealing plug designed in the present application can be applied to a process shaft in poor geological conditions such as an alteration zone and a fracture zone, and provides sealing function for an underground water-sealed cavern project.

[0062] The technical features of the above-described embodiments can be combined in any manner, and for the sake of brevity, not all possible combinations of the technical features in the above-described embodiments are described, however, as long as the combinations of the technical features do not contradict each other, they should be considered within the scope of the present disclosure.

Claims

1. A method for determining parameters of a sealing plug for a vertical shaft of a water-sealed underground storage cavern, characterized in that The application relates to a method for determining the size parameters of a sealing plug for a groundwater-sealed cavern shaft, wherein the sealing plug comprises an integral main column (00) and no less than two annular protrusions, the protrusions are circumscribed to the outer circumference of the main column (00) and extend radially outward along the main column (00); the cross section of the protrusions along the length direction of the main column is triangular; the sealing plug satisfies the following formula: ； In the formula: is a structure important coefficient; is a design condition coefficient; G1 is the self-weight of the sealing plug; G2 is the self-weight of the backfill bentonite; G3 is the self-weight of the filling water; F is a process pipeline load; θ i is an angle between the ith protrusion lower side wall and the vertical direction from top to bottom, i is 1, 2, …n, and n≥2; θ n is an angle between the nth protrusion lower side wall and the vertical direction; is a basic combined structure coefficient; f R is a shear friction coefficient of the concrete and bedrock contact surface; G i is the self-weight of the partial sealing plug up to the ith protrusion lower side wall, C R is a shear cohesion of the concrete and bedrock contact surface; λ is an effective area coefficient of the contact surface; A is a side surface area of the sealing plug in contact with the shaft bedrock surface; From top to bottom, the upper edge of the first protrusion is flush with the upper edge of the column, and the lower edge of the last protrusion is flush with the lower edge of the column; The method comprises the following steps: S1, calculating the self-weight of backfill bentonite G2, the self-weight of filling water G3 and the load of process pipeline F; S2, determining the position of the sealing plug in the shaft and the shear friction coefficient f of the concrete-rock interface R ' and the shear cohesion C of the concrete-rock interface R ' S3, determining the sealing plug size parameters H, d0, di, h i-1 , h i-2 , θ i , Hi; H is the total height of the sealing plug, d0 is the diameter of the main column (00), di is the ring width of the i-th protrusion from top to bottom, h i-1 is the height of the upper wall of the i-th protrusion, h i-2 is the height of the lower wall of the i-th protrusion, θ i is the vertical angle of the lower wall of the i-th protrusion from top to bottom, i is 1, 2, … n, n≥2; Hi is the height of the part of the sealing plug to the lower wall of the i-th protrusion; and calculating the self-weight G1 of the sealing plug; S4, calculating the function S(.) of the effect of the sealing plug and the function R(.) of the anti-sliding stability resistance, , ; θ n is the angle between the lower side wall of the nth protrusion and the vertical direction; G i is the self-weight of the sealing plug up to the ith protrusion lower side wall; θ i is the angle between the ith protrusion lower side wall from top to bottom and the vertical direction, i is 1, 2, … n, n≥2; λ is the effective area coefficient of the contact surface; A is the lateral surface area of the sealing plug in contact with the shaft bedrock surface; S5, if the following conditions are satisfied , is a structural importance coefficient; is a design condition coefficient; is a basic combination structure coefficient; That is, If yes, the design is completed, otherwise go to S3.

2. The method according to claim 1, wherein The ring width of the protrusions is 1.0m-2.0m.

3. The method according to claim 1, wherein From top to bottom, the ring width of the protrusions is gradually increased.

4. The method according to claim 1, wherein From top to bottom, the height of the protrusions is gradually increased.

5. The method of claim 1, wherein, The sealing plug further comprises a first column (11), and the lower end of the first column (11) is connected to the upper end of the main column (00) integrally.

6. The method according to claim 5, wherein The height of the first column (11) is 0.5m-1.0m.

7. The method according to claim 1 or 5, wherein The sealing plug further comprises a second column (22), and the upper end of the second column (22) is connected to the lower end of the main column (00) integrally.

8. The method according to claim 7, wherein The height of the second column (22) is 0.5m-1.0m.

9. The method according to claim 1, wherein, The sealing plug further comprises a first column (11) and a second column (22), and S3 further comprises determining the height h1 of the first column (11) and / or determining the height h2 of the second column (22).

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