Water head pipeline laying device for water conservancy and hydropower construction

Abstract

This utility model discloses a device for laying water intake pipes in water conservancy and hydropower construction, belonging to the field of water conservancy and hydropower construction technology. It includes a water intake pipe trench, with a layer of sand and gravel base laid at the bottom of the trench. An anti-settlement support component is installed on the sand and gravel base. An anti-settlement pipe slope compensation component is located between the first water intake pipe and the anti-settlement support component. The anti-settlement pipe slope compensation component elastically applies upward force to the anti-settlement support component to support the first water intake pipe. When settlement occurs in the water intake pipe trench, causing the slope of the first water intake pipe to bend and sink, the anti-settlement pipe slope compensation component immediately supports the first water intake pipe, thus instantly compensating for the slope settlement. When local settlement occurs in the trench, the spring in the compensation component responds, supporting the pipe upwards to prevent the first water intake pipe from sinking and bending due to settlement.

Description

Technical Field

[0001] This utility model belongs to the field of water conservancy and hydropower construction technology, and in particular, it is a device for laying water intake head pipelines in water conservancy and hydropower construction. Background Technology

[0002] In water conservancy and hydropower engineering construction, the water intake system is a key component ensuring the stable operation of the entire project. The intake head pipeline laying device, as the basic structure of the water intake system, is mainly used to introduce water from natural water bodies to pumping stations or treatment facilities. Its construction quality directly affects the safety, stability, and long-term operational efficiency of the entire water intake system.

[0003] Traditional water intake pipelines are mostly laid directly in excavated trenches, relying on the weight of the soil and local support to maintain the slope and position of the pipeline. However, under complex geological conditions (such as soft soil, collapsible loess, and high groundwater levels), traditional laying methods are prone to problems such as pipeline subsidence and breakage due to uneven foundation settlement, which can lead to serious consequences such as poor drainage, leakage, or even system failure. Utility Model Content

[0004] The purpose of this utility model is to provide a device for laying water intake pipes in water conservancy and hydropower construction, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a water intake head pipeline laying device for water conservancy and hydropower construction, comprising a water intake head pipeline trench excavated in the laying area according to design requirements, the water intake head pipeline trench being excavated at an incline and having a slope, a layer of sand and gravel base being laid at the bottom of the water intake head pipeline trench, an anti-settlement support component being installed on the sand and gravel base, a first water intake pipe and a second water intake pipe being laid on the anti-settlement support component and connected together, the end of the second water intake pipe away from the first water intake pipe being connected to a water intake head, an anti-settlement pipeline slope compensation component being provided between the first water intake pipe and the anti-settlement support component, the anti-settlement pipeline slope compensation component elastically applying upward force on the anti-settlement support component to support the first water intake pipe, the anti-settlement pipeline slope compensation component being able to immediately support the first water intake pipe when settlement occurs at the water intake head pipeline trench below the first water intake pipe, causing the slope of the first water intake pipe to bend and sink, thereby immediately compensating for the slope settlement of the first water intake pipe.

[0006] In this preferred embodiment, the anti-settlement pipeline slope compensation component includes a support base plate installed on the anti-settlement support component, two compensation springs symmetrically installed on the slope surface of the support base plate, and an arc-shaped lower support compensation plate installed at the top of the two compensation springs. The arc-shaped lower support compensation plate supports and lifts the lower part of the first water intake pipe.

[0007] In this preferred embodiment, an air buffer spring is fixedly installed between the two compensation springs and on the slope of the supporting base plate, with the buffer free end of the air buffer spring elastically abutting the back of the arc-shaped lower support compensation plate.

[0008] In this preferred embodiment, positioning rods are welded to both ends of the back of the arc-shaped lower support compensation plate, and the ends of the two positioning rods away from the arc-shaped lower support compensation plate extend longitudinally into the support base plate.

[0009] In this preferred embodiment, the anti-settlement support assembly includes a first steel cage layer fixed to the top surface of the sand and gravel base layer, a sand and gravel support layer laid on the first steel cage layer, and a second steel cage layer laid and fixed on the sand and gravel support layer. The support base plate is fixed to the second steel cage layer by bolts.

[0010] In a preferred embodiment, a pipe slope limiting component is provided above the first water intake pipe and at the top of the water intake head pipe trench. Grooves are symmetrically excavated on both sides of the top of the water intake head pipe trench. A sand and gravel foundation is laid at the bottom of each groove. A concrete support is poured on the sand and gravel foundation. The pipe slope limiting component is installed on the two concrete supports.

[0011] In this preferred embodiment, the pipeline slope limiting component includes a T-shaped limiting rod mounted on two opposing concrete supports and an arc-shaped upper cover plate welded to the bottom of the T-shaped limiting rod, such that the longitudinal body of the T-shaped limiting rod hangs down into the water intake head pipeline trench, and the arc-shaped upper cover plate fits snugly over the upper part of the first water intake pipe.

[0012] In a preferred embodiment of this design, a connector is provided between the first water intake pipe and the second water intake pipe, and connector protection components are provided on both sides of the connector, so that the connector protection components clamp the connection between the first water intake pipe and the second water intake pipe.

[0013] In a preferred embodiment, the joint protection assembly includes two arc-shaped protective clamps symmetrically clamped on both sides of the joint connection portion. Each of the two arc-shaped protective clamps has an installation side plate connected to its bottom at one of its opposite ends. The installation side plates are bolted to the second reinforcing cage layer.

[0014] In this preferred embodiment, the inner walls of both the arc-shaped upper cover plate and the arc-shaped lower support compensation plate are bonded with rubber anti-slip pads, which elastically abut against the outer wall of the first water intake pipe, and a soil layer is present below the sand and gravel base layer.

[0015] Compared with the prior art, the technical effects and advantages of this utility model are as follows:

[0016] The water intake pipe laying device for this water conservancy and hydropower construction has a slope compensation component for anti-settlement pipe installed below the first water intake pipe. This component has an elastic support structure. When local settlement occurs in the trench, the spring or buffer in the compensation component will automatically respond and lift the pipe upward to prevent the first water intake pipe from sinking and bending due to settlement, avoid water accumulation and siltation in the pipe, maintain the continuity of the overall slope of the pipe, ensure smooth water flow, and improve drainage efficiency.

[0017] The first and second water intake pipes are fixedly connected and jointly erected on a flexible support. The compensation component can respond differently to settlement at different locations. Even if uneven settlement occurs in a certain section of the trench, the slope between the two pipes can be kept consistent through the compensation component, effectively avoiding backflow and flow interruption caused by slope misalignment, and improving the stability and reliability of the entire water intake.

[0018] By setting up a pipe slope limiting component, which consists of a T-shaped limiting rod and an arc-shaped upper cover plate, the symmetrically arranged arc-shaped upper cover plate and arc-shaped lower support compensation plate clamp the pipe. The rubber anti-slip pad increases friction to prevent slippage and protects the pipe wall. The limiting structure can prevent the compensation component from lifting too high, causing the pipe to detach or stress concentration. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of this utility model;

[0021] Figure 2 This is a schematic diagram of the connector connection part of this utility model;

[0022] Figure 3 This is a schematic diagram of the installation of the compensation spring component of this utility model;

[0023] Figure 4 This is a schematic diagram of the arc-shaped lower support compensation plate of this utility model;

[0024] Figure 5 This is a schematic diagram of the joint protection component of this utility model;

[0025] Figure 6 This is a schematic diagram showing the connection between the T-shaped lifting rod and the concrete support of this utility model;

[0026] Figure 7This is a schematic diagram of the anti-settlement support component of this utility model.

[0027] Explanation of reference numerals in the attached figures:

[0028] In the diagram: 1. Water intake head trench; 2. First water intake pipe; 3. Second water intake pipe; 4. Water intake head; 5. Soil layer; 6. Arc-shaped upper cover plate; 7. Arc-shaped lower support compensation plate; 8. Pipeline slope limiting component; 9. Anti-settlement support component; 10. Anti-settlement pipeline slope compensation component; 11. Sand and gravel base layer; 12. Joint protection component; 13. Joint connection part; 14. T-shaped limiting rod; 15. Concrete support; 16. Support base plate; 17. Air buffer spring; 18. Elastic positioning seat; 19. Compensation spring component; 20. Positioning upright; 21. Rubber anti-slip mat; 22. Arc-shaped protective clamp; 23. Installation side plate; 24. Sand and gravel foundation; 25. Anchor bolt; 26. First reinforcing cage layer; 27. Second reinforcing cage layer; 28. Sand and gravel support layer. Detailed Implementation

[0029] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid confusion with the present invention.

[0030] Unless otherwise defined, the directions mentioned herein, such as up, down, left, right, front, back, inside, and outside, are based on the directions shown in the figures of this utility model, and are explained here together.

[0031] This embodiment provides, for example Figures 1 to 7The illustrated water intake pipe laying device for hydropower construction includes a water intake pipe trench 1 excavated in the laying area according to design requirements. The water intake pipe trench 1 is excavated at an incline and has a slope. A layer of sand and gravel base 11 is laid at the bottom of the water intake pipe trench 1. An anti-settlement support component 9 is installed on the sand and gravel base 11. A first water intake pipe 2 and a second water intake pipe 3, which are connected together, are laid on the anti-settlement support component 9. The end of the second water intake pipe 3 away from the first water intake pipe 2 is connected to a water intake head 4. There is an anti-settlement pipe slope compensation component 10 between the first water intake pipe 2 and the anti-settlement support component 9. The anti-settlement pipe slope compensation component 10 elastically applies upward force on the anti-settlement support component 9 to support the first water intake pipe 2. When the first water intake pipe 2 sinks due to settlement at the water intake head pipe trench 1 below the first water intake pipe 2, the anti-settlement pipe slope compensation component 10 immediately supports the first water intake pipe 2, thereby immediately compensating for the slope settlement of the first water intake pipe 2. The anti-settlement pipe slope compensation component 10 is designed to lift the end of the first water intake pipe 2 that is away from the second water intake pipe 3, preventing the first water intake pipe 2 from sinking due to the settlement of the water intake head pipe trench 1. The misalignment of the slopes of the first water intake pipe 2 and the second water intake pipe 3 is not conducive to drainage. The function of the anti-settlement pipe slope compensation component 10 is that even if a part of the water intake head pipe trench 1 located below the first water intake pipe 2 settles, the anti-settlement pipe slope compensation component 10 can immediately lift the first water intake pipe 2 to prevent the first water intake pipe 2 from sinking and causing drainage difficulties, thereby always maintaining the slope of the first water intake pipe 2 and the second water intake pipe 3.

[0032] In this embodiment, the anti-settlement pipeline slope compensation component 10 includes a support base plate 16 installed on the anti-settlement support component 9, two compensation springs 19 symmetrically installed on the slope surface of the support base plate 16, and an arc-shaped lower support compensation plate 7 installed at the top of the two compensation springs 19. The arc-shaped lower support compensation plate 7 supports and lifts the lower part of the first water intake pipe 2. Elastic positioning seats 18 are symmetrically welded to both ends of the opposite sides of the support base plate 16 and the arc-shaped lower support compensation plate 7. Both ends of each compensation spring 19 are respectively fixedly installed in the elastic positioning seats 18 on the opposite sides of the arc-shaped lower support compensation plate 7 and the support base plate 16 by bolts, so that the compensation spring 19 acts elastically between the upper and lower elastic positioning seats 18.

[0033] In this embodiment, an air buffer spring 17 is fixedly installed between the two compensating spring members 19 and on the slope of the supporting base plate 16. The buffer free end of the air buffer spring 17 elastically abuts against the back of the arc-shaped lower support compensating plate 7.

[0034] In this embodiment, positioning rods 20 are welded to both ends of the back of the arc-shaped lower support compensation plate 7. The ends of the two positioning rods 20 away from the arc-shaped lower support compensation plate 7 extend longitudinally into the support base plate 16. When the first water intake pipe 2 vibrates (shakes) in the arc-shaped lower support compensation plate 7 or when the compensation spring 19 immediately lifts and compensates for the slope of the first water intake pipe 2, the positioning rods 20 can ensure the positioning accuracy of the longitudinal lifting and lowering movement of the arc-shaped lower support compensation plate 7 and prevent the arc-shaped lower support compensation plate 7 from tilting or misaligning.

[0035] In this embodiment, the anti-settlement support assembly 9 includes a first steel cage layer 26 fixed on the top surface of the sand and gravel base layer 11, a sand and gravel support layer 28 laid on the first steel cage layer 26, and a second steel cage layer 27 laid and fixed on the sand and gravel support layer 28. The support base plate 16 is fixed to the second steel cage layer 27 by bolts.

[0036] In this embodiment, a pipe slope limiting component 8 is provided above the first water intake pipe 2 and at the top of the water intake head pipe trench 1. Grooves are symmetrically excavated on both sides of the top of the water intake head pipe trench 1. A sand and gravel foundation 24 is laid at the bottom of each groove. A concrete support 15 is poured on the sand and gravel foundation 24. The pipe slope limiting component 8 is installed on the two concrete supports 15.

[0037] In this embodiment, the pipeline slope limiting component 8 includes a T-shaped limiting rod 14 mounted on two opposing concrete supports 15 and an arc-shaped upper cover plate 6 welded to the bottom end of the T-shaped limiting rod 14, such that the longitudinal body of the T-shaped limiting rod 14 hangs down into the water intake head pipeline trench 1, and the arc-shaped upper cover plate 6 fits snugly over the upper part of the first water intake pipe 2. The arc-shaped upper cover plate 6 and the arc-shaped lower support compensation plate 7 are arranged symmetrically from top to bottom. Both ends of the top transverse body of the T-shaped limiting rod 14 are connected to the two concrete supports 15 by anchor rods 25. When the anti-settlement pipe slope compensation component 10 lifts the first water intake pipe 2 upwards to compensate for the slope, the arc-shaped upper cover plate 6 can limit the height of the first water intake pipe 2 to prevent it from being lifted beyond its height travel. The position of the arc-shaped upper cover plate 6 is fixed by the T-shaped limit rod 14, and the arc-shaped upper cover plate 6 presses down on the first water intake pipe 2 to prevent it from being lifted beyond its height travel.

[0038] In this embodiment, a connector 13 is provided between the first water intake pipe 2 and the second water intake pipe 3. Connector protection components 12 are provided on both sides of the connector 13, so that the connector protection components 12 clamp the connection between the first water intake pipe 2 and the second water intake pipe 3, preventing tilting, misalignment, and leakage.

[0039] In this embodiment, the joint protection assembly 12 includes two arc-shaped protective clamps 22 symmetrically clamped on both sides of the joint connection portion 13. Each arc-shaped protective clamp 22 has a mounting side plate 23 connected to its opposite end at its bottom. The mounting side plates 23 are bolted to the second reinforcing cage layer 27. This allows the two arc-shaped protective clamps 22 to centripetally clamp the joint connection portion 13 onto the second reinforcing cage layer 27.

[0040] In this embodiment, rubber anti-slip pads 21 are adhered to the inner walls of both the arc-shaped upper cover plate 6 and the arc-shaped lower support compensation plate 7. The rubber anti-slip pads 21 elastically abut against the outer wall of the first water intake pipe 2, and a soil layer 5 is located below the sand and gravel base layer 11. The design of the rubber anti-slip pads 21 not only increases the friction between the rubber pads and the first water intake pipe 2, preventing the first water intake pipe 2 from sliding and misaligning, but also protects the first water intake pipe 2 from being scratched on its outer wall.

[0041] Working principle

[0042] The water intake head pipeline laying device for this water conservancy and hydropower construction involves conducting on-site surveys based on project requirements and topographic and geological conditions to determine the direction, slope, and burial depth of the water intake pipeline. In accordance with design requirements, a water intake head pipeline trench 1 with an inclined direction and a certain slope is excavated in the designated area to ensure that it meets the natural slope required for drainage.

[0043] A layer of sand and gravel base 11 is laid at the bottom of the water intake head pipe trench 1 to level, enhance bearing capacity and drainage. A first steel cage layer 26 is laid on the sand and gravel base 11 to enhance the overall stability of the foundation. A sand and gravel support layer 28 is laid on the steel cage layer, and then a second steel cage layer 27 is laid on top of it to form a composite structure. This structure can effectively distribute the load and prevent uneven settlement of the foundation.

[0044] The supporting base plate 16 is fixed to the second steel cage layer 27 with bolts, serving as the base platform for subsequent slope compensation components. The first water intake pipe 2 and the second water intake pipe 3, which are interconnected, are laid on the supporting base plate 16. The end of the second water intake pipe 3 is connected to the water intake head 4 for introducing water. The first water intake pipe 2 and the second water intake pipe 3 are connected by a joint connection part 13. A joint protection component 12 is set on both sides of the joint, which is clamped by two arc-shaped protective clamps 22 and fixed to the second steel cage layer 27 by installing side plates 23 to prevent the joint from misaligning and leaking due to vibration or settlement.

[0045] Two compensating springs 19 are symmetrically installed on the slope of the supporting base plate 16. The top of the compensating spring 19 is connected to the arc-shaped lower support compensating plate 7, which is used to support the first water intake pipe 2. The arc-shaped lower support compensating plate 7 is connected to the supporting base plate 16 through an elastic positioning seat 18, so that the compensating spring 19 can elastically expand and contract between them. An air buffer spring 17 is set in the middle to help absorb vibration and provide additional buffer. The positioning pole 20 passes through the arc-shaped lower support compensating plate 7 and the supporting base plate 16 to ensure accurate positioning during the lifting process and prevent deviation.

[0046] When the trench 1 below the first water intake pipe 2 experiences localized settlement, the compensation spring 19 and air buffer spring 17 in the anti-settlement pipe slope compensation component 10 will exert upward force to immediately lift the arc-shaped lower support compensation plate 7, thereby supporting the first water intake pipe 2 and preventing it from sinking and causing slope changes or breakage.

[0047] Grooves are excavated on both sides of the top of the water intake pipe trench 1, and a sand and gravel foundation 24 is laid. Concrete supports 15 are then poured on top of the foundation. A T-shaped limiting rod 14 is erected between the two concrete supports 15, and an arc-shaped upper cover plate 6 is welded to its bottom. This cover is placed above the first water intake pipe 2. The two ends of the T-shaped limiting rod 14 are fixed to the concrete supports 15 by anchor rods 25. The arc-shaped upper cover plate 6 and the arc-shaped lower support compensation plate 7 are arranged symmetrically above and below to clamp the first water intake pipe 2. When the compensation component 10 lifts the first water intake pipe 2, the arc-shaped upper cover plate 6 can limit its rising height to prevent excessive lifting. At the same time, rubber anti-slip pads 21 are pasted on the inner walls of the arc-shaped upper cover plate 6 and the arc-shaped lower support compensation plate 7 to increase friction and prevent the pipe from sliding and misaligning, while also providing a buffer protection function.

[0048] After all pipeline installation and protection are completed, backfilling is carried out in layers. The backfill materials include sand, gravel, and plain soil, and each layer is compacted to prevent later settlement from affecting the pipeline.

[0049] It should be noted that, in this document, relational terms such as "one" and "two" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, the phrase "comprising an element defined as..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0050] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A water intake head pipeline laying device for water conservancy and hydropower construction, comprising a water intake head pipeline trench (1) excavated in an inclined direction and having a slope in the laying area, a first water intake pipe (2) and a second water intake pipe (3) located in the water intake head pipeline trench and connected to each other, the second water intake pipe (3) being connected to a water intake head (4). characterized in that A layer of sand and gravel base (11) is laid at the bottom of the water intake head pipe trench (1), and an anti-settlement support component (9) is installed on the sand and gravel base (11). The first water intake pipe (2) and the second water intake pipe (3) are laid on the anti-settlement support component (9). The anti-settlement support component (9) has an anti-settlement pipe slope compensation component (10) above it, which provides elastic support for the lower part of the first water intake pipe (2); A pipe slope limiting component (8) is provided, which has an arc-shaped top cover plate (6) located above the first water intake pipe (2) to limit the upward height of the first water intake pipe.

2. The water conservancy and hydropower construction water intake head pipe laying device according to claim 1, characterized in that: The anti-settlement pipeline slope compensation component (10) includes a support base plate (16) installed on the anti-settlement support component (9), two compensation springs (19) symmetrically installed on the slope of the support base plate (16), and an arc-shaped lower support compensation plate (7) installed on the top of the two compensation springs (19). The arc-shaped lower support compensation plate (7) supports and lifts the lower part of the first water intake pipe (2).

3. The water conservancy and hydropower construction water intake head pipe laying device according to claim 2, characterized in that: An air buffer spring (17) is fixedly installed between the two compensation springs (19) and on the slope of the support base plate (16). The buffer free end of the air buffer spring (17) elastically abuts against the back of the arc-shaped lower support compensation plate (7).

4. The water intake head pipeline laying device for water conservancy and hydropower construction according to claim 3, characterized in that: Positioning rods (20) are welded to both ends of the back of the arc-shaped lower support compensation plate (7). The ends of the two positioning rods (20) that are away from the arc-shaped lower support compensation plate (7) are longitudinally inserted into the support base plate (16).

5. The water intake head pipeline laying device for water conservancy and hydropower construction according to claim 4, characterized in that: The anti-settlement support assembly (9) includes a first steel cage layer (26) fixed on the top surface of the sand and gravel base layer (11), a layer of sand and gravel support layer (28) laid on the first steel cage layer (26), and a second steel cage layer (27) laid and fixed on the sand and gravel support layer (28). The support base plate (16) is fixed to the second steel cage layer (27) by bolts.

6. The water intake head pipeline laying device for water conservancy and hydropower construction according to claim 1, characterized in that: The pipe slope limiting component (8) is set above the first water intake pipe (2) and at the top of the water intake head pipe trench (1). The top two sides of the water intake head pipe trench (1) are symmetrically excavated with grooves. Each groove has a sand and gravel foundation (24) at the bottom. A concrete support (15) is poured on the sand and gravel foundation (24). The pipe slope limiting component (8) is installed on the two concrete supports (15).

7. A water intake head pipeline laying device for water conservancy and hydropower construction according to claim 6, characterized in that: The pipeline slope limiting assembly (8) includes a T-shaped limiting rod (14) mounted on two opposite concrete supports (15). The arc-shaped upper cover plate (6) is welded to the bottom end of the T-shaped limiting rod (14), so that the longitudinal rod of the T-shaped limiting rod (14) hangs down into the water intake head pipeline groove (1), and the arc-shaped upper cover plate (6) fits and covers the upper part of the first water intake pipe (2).

8. A device for laying water intake pipes for water conservancy and hydropower construction according to claim 5, characterized in that: A connector (13) is provided between the first water intake pipe (2) and the second water intake pipe (3). A connector protection component (12) is provided on both sides of the connector (13) so that the connector protection component (12) clamps the connection between the first water intake pipe (2) and the second water intake pipe (3).

9. A device for laying water intake pipes for water conservancy and hydropower construction according to claim 8, characterized in that: The joint protection assembly (12) includes two arc-shaped protective clamps (22) symmetrically clamped on both sides of the joint connection part (13). The bottom of the two arc-shaped protective clamps (22) at opposite ends is connected to an installation side plate (23). The installation side plate (23) is installed on the second steel cage layer (27) by bolts.

10. A device for laying water intake pipes for water conservancy and hydropower construction according to claim 7, characterized in that: The inner walls of the arc-shaped upper cover plate (6) and the arc-shaped lower support compensation plate (7) are both bonded with rubber anti-slip pads (21), which elastically abut against the outer wall of the first water intake pipe (2). There is a soil layer (5) below the sand and gravel base layer (11).

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