Anti-bursting structure device for gully of mold bag sand cofferdam

Abstract

The invention relates to the technical field of river cofferdam construction, in particular to a bursting prevention structure device for a gully of a mold bag sand cofferdam. Comprising a protection assembly, the protection assembly comprises a plurality of plastic nets, a plurality of plastic balls and a plurality of grouting layers, the multiple grouting layers are arranged between every two adjacent plastic nets, each grouting layer is correspondingly provided with an area, the multiple plastic balls are arranged in each area, and a plurality of grouting mold bags are arranged in each grouting layer; cement is injected into the grouting mold bags, and each grouting mold bag and each plastic ball are connected with the plastic net; the radiuses of the plastic balls in different areas are set according to the depth of the areas in the specific position of the gully, and the total grouting amount of the grouting mold bags in different grouting layers is set according to the depth of the grouting layers in the specific position of the gully and the river flow velocity of the river channel in previous years; and the mold bag sand at the riverbed foundation part is prevented from being damaged, so that the stability of the whole cofferdam is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of river cofferdam construction, in particular to a bag sand cofferdam gully bursting prevention structure device. Background Art

[0002] A cofferdam is a temporary retaining structure used during the construction of permanent water conservancy facilities. Its purpose is to prevent water and soil from entering the building site, allowing for drainage, excavation, and construction within the cofferdam. Sand-bag cofferdams, on the other hand, utilize bags made of a special polyethylene material and filled with sand, gravel, and other materials to form a long water barrier. Due to their relatively low cost, durability, and reusability, sand-bag cofferdams are widely used in water conservancy projects.

[0003] The prior art CN113006108B discloses a method for constructing a film bag sand cofferdam, comprising the following steps: riverbed trimming; paving the base film bag sand; paving the secondary film bag sand group: the secondary film bag sand group includes more than two layers of secondary film bag sand, and when the secondary film bag sand group is paved, the secondary film bag sand is paved layer by layer from the base film bag sand to the preset water level elevation until the secondary film bag sand group reaches the preset water level elevation; paving the top film bag sand group: the top film bag sand group includes at least one top film bag sand group. When laying sand bags and the top layer of membrane bag sand, the top layer of membrane bag sand is laid layer by layer from the second layer of membrane bag sand group to the preset height until the top layer of membrane bag sand group reaches the preset height; steel sheet pile construction: after the base layer of membrane bag sand, the second layer of membrane bag sand group and the top layer of membrane bag sand group are laid, steel sheet piles are driven along the width of the riverbed on the inner side, and the base layer of membrane bag sand and the second layer of membrane bag sand group are made to rest against the steel sheet piles. This membrane bag sand cofferdam construction method can prevent serious slippage of the weir body and improve the stability of the cofferdam.

[0004] However, in actual construction, there are many gullies at the bottom of the riverbed, and the gullies need to be filled with mold bag sand to ensure the flatness of the riverbed bottom. However, during use, the mold bag sand in the gullies will settle, causing the mold bag sand at the foundation of the lower part of the riverbed to be destroyed, thereby affecting the stability of the entire cofferdam.

[0005] Therefore, there is an urgent need to provide a mold bag sand cofferdam gully to prevent the top break structure device, compared with the existing technology, to avoid the mold bag sand at the riverbed foundation part from being destroyed, thereby ensuring the stability of the entire cofferdam. Summary of the Invention

[0006] The present invention solves the technical problems existing in the prior art and provides a structural device for preventing a mold bag sand cofferdam gully from bursting.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A bag sand cofferdam gully burst prevention structure device comprises a protective component, wherein the protective component comprises multiple plastic nets, multiple plastic balls and multiple grouting layers, multiple grouting layers are arranged between two adjacent plastic nets, each grouting layer corresponds to an area, multiple plastic balls are arranged in each area, multiple grouting mold bags are arranged in each grouting layer, cement is injected into the grouting mold bags, and each grouting mold bag and each plastic ball are connected to the plastic net; the radius of the plastic balls in different areas is set according to the depth of the area at the specific location of the gully, and the total grouting amount of the grouting mold bags in different grouting layers is set according to the depth of the grouting layer at the specific location of the gully and the river flow rate of the river channel in previous years.

[0009] Furthermore, N grouting layers are set, and the N grouting layers divide the space between two adjacent plastic nets into N areas. The specific method for determining the radius of the plastic ball in each area is as follows: construct a three-dimensional gully model, screen out all points with a Z coordinate of 0 in the three-dimensional gully model to form a sampling surface, take multiple sampling points from the sampling surface, sort the absolute values of the Z coordinates of the sampling points from large to small to form an absolute value sequence, divide the absolute value sequence into N segments on average to form N groups of absolute value data, and the radii of the plastic balls corresponding to the N areas are obtained according to the N groups of absolute value data.

[0010] Furthermore, the radius of the plastic sphere corresponding to the nth region is calculated by the following formula, where n ranges from 1 to N:

[0011]

[0012] In the above formula, R n represents the radius of the plastic sphere corresponding to the nth region, R N represents the radius of the plastic sphere corresponding to the Nth region, J ni Indicates the absolute value of the Z coordinate of the i-th sampling point in the n-th group of absolute value data, J n(i+1) Indicates the absolute value of the Z coordinate of the (i+1)th sampling point in the nth group of absolute value data. I represents the absolute value of all Z coordinates in each group of absolute value data. i ranges from 1 to I, and J max It represents the maximum value of the distance between the deepest part of the gully and the sand bags at both ends of the river channel, J min It represents the minimum value of the distance between the deepest part of the gully and the mold sand bags at both ends of the river channel, and B represents the side length of the grid in the plastic net.

[0013] Furthermore, N and J max 、J min The following relationships exist:

[0014] when hour,

[0015] when hour,

[0016] In the above formula, J represents the distance between the lowest ends of the river channels on both sides of gully 2.

[0017] Furthermore, the setting of N grouting layers satisfies the following conditions: with the deepest point of the gully as the center, (N-1) concentric rings and a ring along the outer contour of the gully are formed to obtain N grouting layers, which are set as the first grouting layer to the Nth grouting layer. For the second grouting layer to the (N-1)th grouting layer, the distance between two adjacent grouting layers is the same as the radius of the inner circle of the first grouting layer, and the sampling surface area between the Nth grouting layer and the (N-1)th grouting layer is the same as the area enclosed by the inner circle of the first grouting layer.

[0018] Furthermore, the gully three-dimensional model is obtained by three-dimensional laser scanning technology. The gully three-dimensional model is composed of dense points, and each point includes an X coordinate, a Y coordinate, and a Z coordinate.

[0019] Furthermore, the method for determining the total grouting volume of each grouting layer is as follows: obtain the river flow velocity value of the river channel in the previous A years, obtain the maximum river flow velocity value among the multiple river flow velocity values in each year, obtain A sampling flow velocity values, and calculate the gully flow velocity value based on the A sampling flow velocity values; obtain the absolute value of the Z coordinate of each sampling point, divide the sampling points falling in N areas into N sampling point sets, each sampling point set includes the absolute value of the Z coordinate of the sampling points falling in the corresponding area, and calculate the total grouting volume of the corresponding grouting layer based on each sampling point set and the gully flow velocity value.

[0020] Furthermore, the grouting amount of each grouting layer is calculated by the following formula:

[0021] The total grouting volume of the first grouting layer is calculated according to the following formula:

[0022]

[0023] The total grouting volume from the second grouting layer to the (N-1) grouting layer is calculated according to the following formula:

[0024]

[0025] The total grouting volume of the Nth grouting layer is calculated according to the following formula:

[0026]

[0027] In the above formula, Q1 represents the total grouting volume of the first grouting layer, P represents the gully flow velocity, R1 represents the radius of the plastic ball corresponding to the first area, r 11 Indicates the radius of the inner circle of the first grouting layer, r 12 Indicates the radius of the outer circle of the first grouting layer; Qh represents the total grouting volume of the hth grouting layer, where h ranges from 1 to (N-1), H1 represents the mean of the absolute values of the Z coordinates of all sampling points in the first sampling point set, and H h represents the mean of the absolute values of the Z coordinates of all sampling points in the h-th sampling point set; Q N Indicates the total grouting volume of the Nth grouting layer, R N represents the radius of the plastic sphere corresponding to the Nth region, r N1 Indicates the radius of the inner circle of the Nth grouting layer, r N2 Indicates the radius of the outer circle of the Nth grouting layer.

[0028] Furthermore, the gully flow velocity value is calculated according to the following formula:

[0029]

[0030] In the above formula, P max Indicates the maximum value among A sampling flow rate values, P a Indicates the ath sampling flow rate value, a is 1-(A-1), (A-1) means removing P max The total number of sampled flow rate values after, P (a+1) Indicates the (a+1)th sampling flow rate value.

[0031] Furthermore, the distance between the inner circle and the outer circle of each grouting layer is the same.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention sets the radius of the plastic ball in the corresponding plastic net according to the three-dimensional model of the gully of different gullies, and then fixes the plastic ball to the plastic net, and sets a plurality of grouting layers in the plastic net, each grouting layer corresponds to an area, and the radius of the plastic ball set in each area is different, and the radius of the plastic ball is set according to the depth of the gully. At the same time, the total grouting amount of the grouting layer is calculated according to the depth of the gully and the river flow rate values of the river channel in previous years, so that the protective components corresponding to each gully can be divided and set according to the depth of different positions of the gully and the river flow rate values of the river channel in previous years, ensuring that the protective components can generate small-scale arc fluctuations with the flow of the river during use, and can also ensure that the protective components generate a small displacement deviation in the flow direction of the river, avoiding the formation of spikes in the mold bag sand in the gully, and can well protect the mold bag sand at the foundation of the river channel, avoiding the destruction of the mold bag sand at the foundation, thereby ensuring the stability and safety of the mold bag sand cofferdam. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a front view of the overall structure of the present invention.

[0035] Figure 2It is a schematic diagram of a top view of the protective component of the present invention.

[0036] Description of reference numerals:

[0037] 1. Mold bag sand; 2. Gully; 3. Protective components; 31. Plastic net; 32. Plastic ball; 33. Grouting layer. DETAILED DESCRIPTION

[0038] The technical solution of the present invention will be clearly described below in conjunction with the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. It should be noted that the orientation or position relationship indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", etc. is based on the orientation or position relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description. It does not indicate or imply 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 a limitation of the present invention.

[0039] like Figure 1 As shown, the interior of the gully 2 at the bottom of the river channel is filled with mold bag sand 1, and mold bag sand 1 is also placed on both sides of the river channel to form a stepped structure.

[0040] The present invention provides a structural device for preventing the gully from bursting due to a mold bag sand cofferdam, comprising a protective component 3, which is arranged at the bottom of a river channel. Specifically, the protective component 3 covers the gully 2, and the two ends of the protective component 3 are respectively connected to the mold bag sand 1 at both ends of the river channel through geotextiles.

[0041] like Figure 2 As shown, the protective component 3 includes two plastic nets 31 arranged one above the other. The area enclosed by the plastic nets 31 is adapted to the top view size of the gully 2. A plurality of plastic balls 32 are arranged between the two plastic nets 31. The plastic balls 32 are fixedly connected to the plastic nets 31. The plastic nets 31 are composed of a plurality of square grids of the same size. The diameter of the plastic balls 32 is larger than the side length of the square grid.

[0042] The protective component 3 also includes multiple grouting layers 33, each grouting layer 33 is annular. Except for the outermost grouting layer 33, the other grouting layers 33 are circular rings. The annular shape of the outermost grouting layer 33 matches the contour of the gully 2. Except for the outermost grouting layer, the other grouting layers 33 are concentrically arranged. Each grouting layer 33 is provided with multiple grouting mold bags. The grouting mold bags arranged in each grouting layer 33 are fitted together, each grouting mold bag is fixedly connected to the plastic net 31, and cement grouting is performed inside each grouting mold bag. The total injection amount of all grouting mold bags in different grouting layers 33 is different. The multiple grouting layers 33 are sequentially set as the first grouting layer 33 to the Nth grouting layer 33 from the inside to the outside; the multiple grouting layers 33 divide the plastic net 31 into multiple areas, which are sequentially set as the first area to the Nth area from the inside to the outside, and N represents the total number of grouting layers 33; the radius sizes of the plastic balls 32 arranged in the first area to the Nth area are different.

[0043] The radius of the plastic balls 32 in the first area to the Nth area set in the plastic net 31 corresponding to each gully 2 is determined according to the depth of the gully 2. The specific method is: using three-dimensional laser scanning technology, the gully 2 is three-dimensionally laser scanned to obtain a gully three-dimensional model. The gully three-dimensional model is composed of dense points, each point includes an X coordinate, a Y coordinate and a Z coordinate. The Z coordinates of the points corresponding to the gully three-dimensional model are all negative or 0. The points with a Z coordinate of 0 are filtered out to form a sampling surface, and multiple sampling points are taken from the sampling surface. The sampling points are distributed at the edge and internal positions of the gully 2 respectively; the absolute values of the Z coordinates of all sampling points are sorted from large to small to form an absolute value sequence, and the absolute value sequence is evenly divided into N segments to form N groups of absolute value data.

[0044] Set the deepest point of gully 2 on the sampling surface as the concentric point of the grouting layer, set (N-1) concentric rings and a ring around the outer contour of gully 2, and the ring and ring are the grouting layer. The first grouting layer to the Nth grouting layer needs to meet the following conditions: for the second grouting layer to the (N-1)th grouting layer, the distance between the two adjacent grouting layers is the same as the radius of the inner circle of the first grouting layer, and the sampling surface area between the Nth grouting layer and the (N-1)th grouting layer is the same as the area of the inner circle of the first grouting layer; after the positions of the N grouting layers are confirmed, the positions of the N areas are confirmed.

[0045] The radii of the plastic balls 32 corresponding to the first region to the Nth region are obtained according to the first group of absolute value data to the Nth group of absolute value data, respectively.

[0046] The radius of the plastic ball 32 corresponding to the nth region is calculated by the following formula, where n ranges from 1 to N:

[0047]

[0048] In the above formula, Rn represents the radius of the plastic ball 32 corresponding to the nth region, R N represents the radius of the plastic ball 32 corresponding to the Nth region, J ni Indicates the absolute value of the Z coordinate of the i-th sampling point in the n-th group of absolute value data, J n(i+1) represents the absolute value of the Z coordinate of the (i+1)th sampling point in the nth group of absolute value data, I represents the absolute value of all Z coordinates in each group of absolute value data, i ranges from 1 to 1, B represents the side length of the grid in the plastic network 31, J max It represents the maximum value of the distance between the deepest part of the gully and the sand bags at both ends of the river channel, J mib It indicates the minimum value of the distance between the deepest part of the gully and the mold bag sand at both ends of the river channel.

[0049] N and J max 、J min The following relationships exist:

[0050] when hour,

[0051] when hour,

[0052] In the above formula, J represents the distance between the lowest ends of the river channels on both sides of gully 2.

[0053] Smaller plastic balls 32 may be used to fill void spaces in the Nth region.

[0054] The total grouting volume from the first grouting layer to the Nth grouting layer is determined according to the depth of the gully 2 and the river flow velocity of the river channel in previous years. The specific method for determining the total grouting volume of different grouting layers is as follows: obtain the river flow velocity of the river channel in the previous A years, obtain the maximum river flow velocity value among the multiple river flow velocity values of each year, obtain A sampling flow velocity values, and calculate the gully flow velocity value based on the A sampling flow velocity values; obtain the absolute value of the Z coordinate of each sampling point, and divide the sampling points falling in the first area to the Nth area into N sampling point sets, each sampling point set including the absolute value of the Z coordinate of the sampling points falling in the corresponding area, and calculate the grouting volume in the grouting mold bag set in the corresponding grouting layer according to each sampling point set and the gully flow velocity value.

[0055] The total grouting volume of the first grouting layer is calculated according to the following formula:

[0056]

[0057] The total grouting volume from the second grouting layer to the (N-1) grouting layer is calculated according to the following formula:

[0058]

[0059] The total grouting volume of the Nth grouting layer is calculated according to the following formula:

[0060]

[0061] In the above formula, Q1 represents the total grouting volume of the first grouting layer, P represents the gully flow velocity, R1 represents the radius of the plastic ball corresponding to the first area, r 11 Indicates the radius of the inner circle of the first grouting layer, r 12 Indicates the radius of the outer circle of the first grouting layer; Q h represents the total grouting volume of the hth grouting layer, where h ranges from 1 to (N-1), H1 represents the mean of the absolute values of the Z coordinates of all sampling points in the first sampling point set, and H h represents the mean of the absolute values of the Z coordinates of all sampling points in the h-th sampling point set; Q N Indicates the total grouting volume of the Nth grouting layer, R N represents the radius of the plastic sphere corresponding to the Nth region, r N1 Indicates the radius of the inner circle of the Nth grouting layer, r N2 Indicates the radius of the outer circle of the Nth grouting layer.

[0062] The gully flow velocity is calculated according to the following formula:

[0063]

[0064] In the above formula, P max Indicates the maximum value among A sampling flow rate values, P a Indicates the ath sampling flow rate value, a is 1-(A-1), (A-1) means removing P max The total number of sampled flow rate values after, P (a+1) Indicates the (a+1)th sampling flow rate value.

[0065] The grouting mold bags in each grouting layer 33 are only fitted together, and the sizes of the multiple grouting mold bags set in each grouting layer 33 are the same. The sizes of the grouting mold bags set in different grouting layers 33 may be different. Each grouting mold bag is only fixedly connected to the plastic net 31, and the grouting mold bag is not connected to other structures; the distance between the inner circle and the outer circle of each grouting layer 33 is the same.

[0066] The working principle of the mold bag sand cofferdam gully burst prevention structure device provided by the present invention is as follows: according to the gully three-dimensional model of different gullies 2, the radius of the plastic ball 32 in the corresponding plastic net 31 is set, and then the plastic ball 32 is fixedly connected to the plastic net 31, and multiple grouting layers 33 are set in the plastic net 31. Each grouting layer 33 corresponds to an area. The radius of the plastic ball 32 set in each area is different. The radius of the plastic ball 32 is set according to the depth of the gully 2. At the same time, the total grouting amount of the grouting layer 33 is set according to the depth of the gully 2 and the river flow in previous years. The flow velocity value is calculated, so that the protective components 3 corresponding to each gully 2 can be divided into zones according to the depth of different positions of the gully 2 and the river flow velocity values of the river in previous years, to ensure that the protective components 3 can produce small-scale arc fluctuations with the flow of the river during use, and can also ensure that the protective components 3 produce a small displacement deviation in the flow direction of the river, to avoid the formation of spikes in the mold bag sand 1 in the gully 2, and can well protect the mold bag sand 1 at the foundation of the river, to avoid the mold bag sand 1 at the foundation from being damaged, thereby ensuring the stability and safety of the mold bag sand 1 cofferdam.

[0067] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A mold bag sand cofferdam gully to prevent the top break structure device, characterized in that: The invention comprises a protective component, which comprises a plurality of plastic nets, a plurality of plastic balls and a plurality of grouting layers. A plurality of grouting layers are arranged between two adjacent plastic nets, and each grouting layer corresponds to an area. A plurality of plastic balls are arranged in each area, and a plurality of grouting mold bags are arranged in each grouting layer. Cement is injected into the grouting mold bags, and each grouting mold bag and each plastic ball are connected to the plastic net; the radius of the plastic balls in different areas is set according to the depth of the specific position of the area in the gully, and the total grouting amount of the grouting mold bags in different grouting layers is set according to the depth of the specific position of the gully and the river flow rate of the river channel in previous years.

2. A bag sand cofferdam gully anti-burst structure device according to claim 1, characterized in that: N grouting layers are set, and the N grouting layers divide the space between two adjacent plastic meshes into N areas. The specific method for determining the radius of the plastic ball in each area is as follows: construct a three-dimensional gully model, filter out all points with a Z coordinate of 0 in the three-dimensional gully model to form a sampling surface, take multiple sampling points from the sampling surface, sort the absolute values of the Z coordinates of the sampling points from large to small to form an absolute value sequence, and divide the absolute value sequence into N segments on average to form N groups of absolute value data. The radii of the plastic balls corresponding to the N areas are obtained based on the N groups of absolute value data.

3. A bag sand cofferdam gully anti-burst structure device according to claim 2, characterized in that: The radius of the plastic sphere corresponding to the nth region is calculated by the following formula, where n ranges from 1 to N: In the above formula, R n represents the radius of the plastic sphere corresponding to the nth region, R N represents the radius of the plastic sphere corresponding to the Nth region, J ni Indicates the absolute value of the Z coordinate of the i-th sampling point in the n-th group of absolute value data, J n(i+1) Indicates the absolute value of the Z coordinate of the (i+1)th sampling point in the nth group of absolute value data. I represents the absolute value of all Z coordinates in each group of absolute value data. i ranges from 1 to I, and J max It represents the maximum value of the distance between the deepest part of the gully and the sand bags at both ends of the river channel, J min It represents the minimum value of the distance between the deepest part of the gully and the mold sand bags at both ends of the river channel, and B represents the side length of the grid in the plastic net.

4. A bag sand cofferdam gully anti-burst structure device according to claim 3, characterized in that: N and J max 、J min The following relationships exist: when hour, when hour, In the above formula, J represents the distance between the lowest ends of the river channels on both sides of gully 2.

5. The mold bag sand cofferdam gully anti-burst structure device according to claim 2, characterized in that: The setting of N grouting layers meets the following conditions: with the deepest part of the gully as the center, (N-1) concentric rings and a ring along the outer contour of the gully are formed to obtain N grouting layers, which are set as the first grouting layer to the Nth grouting layer. For the second grouting layer to the (N-1)th grouting layer, the distance between two adjacent grouting layers is the same as the radius of the inner circle of the first grouting layer, and the sampling surface area between the Nth grouting layer and the (N-1)th grouting layer is the same as the area enclosed by the inner circle of the first grouting layer.

6. A bag sand cofferdam gully anti-burst structure device according to claim 2, characterized in that: The gully three-dimensional model is obtained by three-dimensional laser scanning technology. The gully three-dimensional model is composed of dense points, and each point includes an X coordinate, a Y coordinate, and a Z coordinate.

7. The mold bag sand cofferdam gully anti-burst structure device according to claim 3, characterized in that: The method for determining the total grouting volume of each grouting layer is as follows: obtain the river flow velocity value of the river channel in the previous A years, obtain the maximum river flow velocity value among multiple river flow velocity values in each year, obtain A sampling flow velocity values, and calculate the gully flow velocity value based on the A sampling flow velocity values; obtain the absolute value of the Z coordinate of each sampling point, divide the sampling points falling in N areas into N sampling point sets, each sampling point set includes the absolute value of the Z coordinate of the sampling points falling in the corresponding area, and calculate the total grouting volume of the corresponding grouting layer based on each sampling point set and the gully flow velocity value.

8. A bag sand cofferdam gully anti-burst structure device according to claim 7, characterized in that: The grouting amount of each grouting layer is calculated by the following formula: The total grouting volume of the first grouting layer is calculated according to the following formula: The total grouting volume from the second grouting layer to the (N-1) grouting layer is calculated according to the following formula: The total grouting volume of the Nth grouting layer is calculated according to the following formula: In the above formula, Q1 represents the total grouting volume of the first grouting layer, P represents the gully flow velocity, R1 represents the radius of the plastic ball corresponding to the first area, r 11 Indicates the radius of the inner circle of the first grouting layer, r 12 Indicates the radius of the outer circle of the first grouting layer; Q h represents the total grouting volume of the hth grouting layer, where h ranges from 1 to (N-1), H1 represents the mean of the absolute values of the Z coordinates of all sampling points in the first sampling point set, and H h represents the mean of the absolute values of the Z coordinates of all sampling points in the h-th sampling point set; Q N Indicates the total grouting volume of the Nth grouting layer, R N represents the radius of the plastic sphere corresponding to the Nth region, r N1 Indicates the radius of the inner circle of the Nth grouting layer, r N2 Indicates the radius of the outer circle of the Nth grouting layer.

9. A bag sand cofferdam gully anti-burst structure device according to claim 8, characterized in that: The gully flow velocity is calculated according to the following formula: In the above formula, P max Indicates the maximum value among A sampling flow rate values, P a Indicates the ath sampling flow rate value, a is 1-(A-1), (A-1) means removing P max The total number of sampled flow rate values after, P (a+1) Indicates the (a+1)th sampling flow rate value.

10. The mold bag sand cofferdam gully anti-burst structure device according to claim 7, characterized in that: The distance between the inner circle and the outer circle of each grouting layer is the same.

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