A variable friction coefficient sliding isolation device with limit

Abstract

The present invention belongs to the field of seismic isolation technology and discloses a variable friction coefficient sliding seismic isolation device with a limit, including a ring beam, a sliding zone is provided at the bottom of the ring beam, the sliding zone includes a first ceramsite layer, the first ceramsite layer is arranged at the bottom of the ring beam; a second ceramsite layer, the second ceramsite layer is symmetrically arranged on both sides of the first ceramsite layer, and the particle size of the second ceramsite layer is smaller than that of the first ceramsite layer; a third ceramsite layer, the third ceramsite layer is symmetrically arranged on both sides of the second ceramsite layer; it also includes a rubber pier arranged on the outside of the third ceramsite layer, the rubber pier is used to limit the sliding displacement of the ring beam, and it also includes an oil tank arranged on the ring beam, the engine oil in the oil tank is poured on the ceramsite to change its friction coefficient; this scheme realizes the change of friction coefficient by arranging ceramsite with particle size ranging from large to small, and the present invention solves the problems in the prior art that the ring beam is difficult to slide due to excessive material friction coefficient, the seismic isolation effect is weak, the sliding displacement of the ring beam is too large due to small friction coefficient, and the seismic isolation device has no limit.

Description

Technical Field

[0001] The present invention belongs to the technical field of seismic isolation, and specifically relates to a variable friction coefficient sliding seismic isolation device with a limiter. Background Art

[0002] Seismic isolation is a method used in construction to reduce the impact of earthquakes on buildings. The basic principle is to install an isolation layer between the building's foundation and superstructure, making it difficult for earthquake energy to be directly transmitted to the superstructure, thereby reducing damage to the building.

[0003] Sliding isolation is a type of seismic isolation technology that involves installing a sliding isolation layer between a building's foundation and superstructure. When an earthquake occurs, ground movement causes the structure to shift horizontally. The sliding isolation layer, through its sliding properties, allows the structure to slide horizontally on the isolation layer to a certain degree, rather than being rigidly connected. This sliding action absorbs and dissipates some of the seismic energy, reducing the impact and vibration on the superstructure, thereby reducing the inertial forces acting on the structure and improving the building's seismic performance.

[0004] Referring to the document with the existing publication (announcement) number CN105887667A, a variable friction isolation bearing is disclosed. The bottom surface of the friction sliding block on the isolation bearing is provided with a friction surface of a special shape. These friction surfaces are defined by even-order curve equations, such as quadratic or quartic function equations, to form a specific profile. When the friction sliding block slides in both directions, horizontally or vertically, on the friction layer on the top of the lower connecting plate, due to the curved shape of the friction surface, the contact area will change with the change of displacement, so that the friction force can be adjusted according to the change of displacement, thereby achieving the effect of a variable friction coefficient. As the displacement increases, the contact area between the friction surfaces increases, resulting in a corresponding increase in friction force, thereby achieving a damping effect that changes with the displacement.

[0005] Isolation bearings that utilize a specific contoured surface to achieve a variable friction coefficient can adjust friction based on displacement, thereby providing a better damping effect. However, this method, which relies on geometric shape changes to adjust friction, can distort the friction surface profile over time due to material wear or deformation, affecting the control of friction changes and reducing the stability of the isolation effect. Furthermore, the contoured surface is highly complex in design and difficult to manufacture, increasing manufacturing costs and maintenance difficulties. Summary of the Invention

[0006] The purpose of this solution is to provide a variable friction coefficient sliding isolation device with a limiter to solve the problem of inconsistent friction coefficient caused by material wear in the prior art.

[0007] In order to achieve the above-mentioned object, the present invention provides a variable friction coefficient sliding isolation device with a limit, comprising a ring beam, wherein a sliding zone is provided at the bottom of the ring beam, and the sliding zone comprises:

[0008] a first ceramsite layer, wherein the first ceramsite layer is provided at the bottom of the ring beam;

[0009] a second ceramsite layer, the second ceramsite layer being symmetrically arranged on both sides of the first ceramsite layer, and the particle size of the second ceramsite layer being smaller than that of the first ceramsite layer;

[0010] The third ceramsite layer is symmetrically arranged on both sides of the second ceramsite layer, and the particle size of the third ceramsite layer is smaller than that of the second ceramsite layer.

[0011] The principle of this solution is to make the ring beam into a convex shape, and the protruding part of the ring beam is the sliding contact surface. The foundation position corresponding to the protruding part is arranged with expanded clay particles of decreasing particle size from the middle to the two ends to realize an increase in the friction coefficient from small to large. The increase in the friction coefficient increases the consumed seismic energy. The purpose is that the greater the displacement of the structure under the action of an earthquake, the greater the seismic force required. Compared with the sliding layer with a smaller friction coefficient, the sliding displacement of the system is smaller. Compared with the sliding layer with a larger friction coefficient, the seismic force required for the initial sliding of the system is smaller, and the sliding layer is easier to enter the working state and play a seismic isolation role.

[0012] The effects of this scheme are as follows: (1) The friction coefficient of the slip zone is variable. The slip zone is divided according to the friction coefficient. Different slip zones have different friction coefficients. The friction coefficient increases gradually from the inside to the outside. Compared with the system with all slip layers with smaller friction coefficients, the system has smaller sliding displacement. Compared with the system with all slip layers with larger friction coefficients, the system requires less seismic force for initial sliding. The slip layer is easier to enter the working state and play a role in seismic isolation. (2) The movement of the ring beam will cause wear of the ceramsite in contact with it. This wear will change the surface roughness and contact area of ​​the ceramsite, thereby affecting the friction coefficient. Generally, the surface of new ceramsite is relatively rough and has a larger friction coefficient, while the surface of the ceramsite after wear becomes relatively smooth, the contact area may decrease, and the friction coefficient decreases accordingly. However, when the upper layer of ceramsite is worn, its volume and weight decrease. Under the vibration of the earthquake, these light-weight worn ceramsite will be pushed by the earthquake force, causing the upper layer of worn ceramsite to move down to the lower layer due to gravity and vibration, while the lower layer of unworn or less worn ceramsite will rise to the upper layer, thereby ensuring the consistency of the friction coefficient of the slip zone.

[0013] Furthermore, a partition is provided between the first ceramsite layer, the second ceramsite layer and the third ceramsite layer.

[0014] The principle and effect of this solution is to prevent the ceramsite in each ceramsite layer from mixing with each other due to earthquake vibration.

[0015] Furthermore, it also includes a rubber pier arranged on the outside of the third ceramsite layer.

[0016] The principle and effect of this solution are: limiting the movement distance of the ring beam, and the elastic characteristics of the rubber pier can also absorb and buffer the impact of the ring beam.

[0017] Furthermore, it also includes an oil tank arranged on the ring beam, and the oil outlet of the oil tank is provided with a rubber plug, and the rubber plug falls off after the oil tank collides with the rubber pier.

[0018] The principle and effect of this scheme are as follows: (1) Because the ceramsite may be slightly worn under the compression and shear state, the friction coefficient increases. The lubrication function is achieved through the oil tank. When the oil tank collides with the rubber pier, the rubber plug falls off, causing the oil in the oil tank to flow out from the oil outlet and as the ring beam slides, the oil is poured onto the friction surface of the ceramsite, thereby reducing the friction coefficient and further reducing the sliding resistance. (2) Under the action of earthquake vibration, the shaking of the ceramsite layer also helps the oil to better penetrate and distribute to the contact points between the ceramsite, achieving a more uniform lubrication effect.

[0019] Furthermore, the oil tank includes a first oil tank, a one-way valve is provided on the first oil tank, the first oil tank is an oil tank made of a flexible material, and the first oil tank is arranged in cooperation with a rubber pier.

[0020] The principle and effect of this solution lies in the fact that when the ring beam slips and causes the first fuel tank to collide with the rubber pier, the deformation of the first fuel tank generates internal pressure, which pushes the oil out of the one-way valve and onto the ceramsite friction surface. This arrangement avoids the problem of the ring beam not moving to the rubber pier, but causing the oil tank rubber plug to fall due to earthquake vibration.

[0021] Furthermore, it also includes a second oil tank, which is connected to the first oil tank through a one-way valve. A baffle and a piston are provided in the second oil tank. The piston is slidingly connected to the inner wall of the second oil tank. The piston is connected to a spring. The free end of the spring is connected to the baffle. The one-way valve is provided between the baffle and the piston. The second oil tank is provided with an oil outlet.

[0022] The principle and effect of this scheme are as follows: (1) After the first oil tank is squeezed by the rubber pier, the oil flows into the space enclosed by the baffle, the inner wall of the second oil tank and the piston, and flows out from the oil outlet and onto the friction surface of the ceramsite. When the amount of oil flowing in increases, it will push the piston upward and stretch the spring. After the ring beam moves in the opposite direction, the second oil tank loses the squeeze of the rubber pier, and the spring drives the piston to reset, thereby squeezing the oil in the enclosed space and causing it to flow out from the oil outlet. (2) The speed and amount of oil outflow are controlled by the baffle, piston and spring. When the first oil tank is squeezed by the rubber pier, the oil flows into the enclosed space and flows out from the oil outlet. As the piston moves upward due to the increase of oil and stretches the spring, after losing the squeeze of the rubber pier, the force of the spring drives the piston to reset and continues to push the oil out, thereby achieving a continuous lubrication effect. This not only avoids the excessive oil outflow speed caused by sudden pressure changes, but also ensures the continuous outflow of oil during the repeated movement of the ring beam.

[0023] Furthermore, the baffle is provided with an oil outlet pipe, the oil inlet end of the oil outlet pipe is provided between the baffle and the piston, and the oil outlet end is provided outside the second oil tank, the oil inlet end of the oil outlet pipe is smaller than the oil outlet end of the oil outlet pipe, and a ball valve is provided in the oil outlet pipe, the diameter of the ball valve is larger than the diameter of the oil inlet end and smaller than the diameter of the oil outlet end, the ball valve is connected to an elastic rope, and the free end of the elastic rope is connected to the piston.

[0024] The principle and effect of this scheme are as follows: (1) When the first oil tank collides with the rubber pier, since the ring beam has not yet moved back, if the oil in the oil tank flows out at this time, it will cause the oil to contact the ceramsite friction surface prematurely. At this time, the ring beam has not yet moved, so the oil cannot effectively cover and lubricate the entire sliding area, resulting in oil waste. Therefore, the oil inside should be allowed to flow out after the first oil tank is squeezed and before it is squeezed. (2) When the first oil tank is squeezed, the oil flows into the enclosed space between the baffle, the inner wall of the first oil tank and the piston, and pushes the piston to move upward, driving the ball valve to move through the elastic rope, so that the ball valve closes the oil inlet end of the oil outlet pipe, thereby preventing the oil in the chamber from flowing out. When the first oil tank loses its squeeze, the piston resets under the drive of the spring, and the elastic rope drives the ball valve to reset, so that the oil outlet pipe and the enclosed space are in a connected state, and the oil flows out at this time. (3) By setting up a ball valve and an elastic rope, the engine oil will not flow out before the ring beam slides. Only when the collision and extrusion are relieved and the ring beam starts to move back, the piston will reset under the action of the spring, driving the ball valve to open, and the engine oil will flow out from the oil outlet pipe. At this time, the ring beam moves, and the engine oil can evenly cover and lubricate the entire sliding area, giving full play to the lubrication effect and avoiding the waste of engine oil.

[0025] Furthermore, the oil outlet pipe is rotatably connected to the baffle, and a section of the oil outlet pipe located between the baffle and the piston is provided with blades.

[0026] The principle and effect of this solution are as follows: (1) After the oil in the enclosed space is squeezed, the blades begin to rotate, causing the oil flowing out of the oil outlet pipe to be sprayed around the ceramsite layer under the action of centrifugal force. (2) The centrifugal force generated by the rotation of the blades can make the oil spray wider and more evenly.

[0027] Furthermore, an inclined oil injection pipe is provided at the oil outlet end of the oil outlet pipe, and the oil injection pipe is connected to the oil outlet pipe.

[0028] The principle and effect of this solution are as follows: the inclined fuel injection pipe makes the flow direction of the engine oil form a certain angle with the oil outlet pipe, generating an additional component force along the outlet direction of the fuel injection pipe. Under the action of centrifugal force, this component force causes the engine oil to be ejected at a wider projection angle, thereby increasing the flight distance of the engine oil, allowing the engine oil to cover a farther area of ​​the ceramsite layer, and ensuring the uniform distribution of the lubricant.

[0029] Furthermore, a slide groove is provided in the second oil tank, and the piston is slidably connected to the slide groove.

[0030] The principle and effect of this solution are that the slide groove provides positioning and guidance for the up and down movement of the piston, thereby preventing dislocation during the movement process. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic structural diagram of a variable friction coefficient sliding isolation device with a limiter according to the present invention;

[0032] Figure 2 Schematic diagram of the internal structure of the oil tank of the present invention.

[0033] The reference numerals in the drawings of the specification include: ring beam 1, sliding zone 2, first ceramsite layer 21, second ceramsite layer 22, third ceramsite layer 23, rubber pier 3, oil tank 4, first oil tank 41, one-way valve 42, second oil tank 43, baffle 44, piston 45, oil outlet pipe 46, ball valve 47, elastic rope 48, and blade 49. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with the embodiments to fully understand the purpose, features and effects of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention:

[0035] Example 1:

[0036] See also Figure 1A variable friction coefficient sliding isolation device with a limiter includes a ring beam 1 and a sliding zone 2 provided at the bottom of the ring beam 1. The sliding zone 2 includes a first ceramsite layer 21, a second ceramsite layer 22, and a third ceramsite layer 23. The first ceramsite layer 21 is provided directly below the ring beam 1. There are two second ceramsite layers 22, and the two second ceramsite layers 22 are symmetrically provided on both sides of the first ceramsite layer 21. There are two third ceramsite layers 23, and the two third ceramsite layers 23 are symmetrically provided on both sides of the second ceramsite layer 22. The first ceramsite layer 21 is coarse-grained ceramsite with a corresponding particle size greater than 5 mm. The second ceramsite layer 22 is medium-grained ceramsite with a corresponding particle size between 2.5 and 5 mm. The third ceramsite layer 23 is fine-grained ceramsite with a corresponding particle size less than 2.5 mm. To ensure that the ceramsite in the first ceramsite layer 21, the second ceramsite layer 22, and the third ceramsite layer 23 do not mix, a partition is provided between each ceramsite layer.

[0037] The ring beam 1 is made into a convex shape, and the protruding part of the ring beam 1 serves as a sliding contact surface. The basic position corresponding to the protruding part is arranged from the middle to the two ends according to the particle size of the ceramsite from large to small to achieve an increase in the friction coefficient from small to large. The increase in the friction coefficient increases the seismic energy consumed. Its purpose is to increase the seismic force required for the structure to be displaced more under the action of an earthquake. Compared with the sliding layer with a smaller friction coefficient, the sliding displacement of the system is smaller. Compared with the sliding layer with a larger friction coefficient, the seismic force required for the initial slip of the system is smaller. The slip zone 2 is easier to enter the working state and play a role in seismic isolation. During an earthquake, the movement of the ring beam 1 will cause the ceramsite in contact with it to wear. This wear will change the surface roughness and contact area of ​​the ceramsite, thereby affecting the friction coefficient of the ceramsite. Generally, the surface of new ceramsite is relatively rough and has a larger friction coefficient, while the surface of the ceramsite after wear becomes relatively smooth, the contact area may decrease, and the friction coefficient decreases accordingly. However, when the upper layer of ceramsite is worn, its volume and weight decrease. Under the vibration of the earthquake, these lightweight worn ceramsites will be pushed by the earthquake force, causing the worn ceramsite in the upper layer to move down to the lower layer due to gravity and vibration, while the unworn or less worn ceramsite in the lower layer rises to the upper layer, thereby ensuring that the friction coefficient of the slip zone 2 is consistent.

[0038] To limit the movement of the ring beam 1, two rubber piers 3 are symmetrically positioned on the sliding zone 2. These piers are constructed from multiple layers of waste rubber (such as used tires). The elastic properties of the rubber piers 3 also absorb and cushion impacts on the ring beam 1. An oil tank 4 is also symmetrically positioned on the ring beam 1. The oil outlet of the oil tank 4 is equipped with a rubber stopper, which falls off when the oil tank 4 collides with the rubber piers 3. Because the ceramsite may experience slight wear under compression and shear, increasing the coefficient of friction, oil is poured onto the ceramsite by the oil tank 4. When the oil tank 4 collides with the rubber piers 3, the rubber stopper falls off, allowing the oil in the oil tank 4 to flow out of the oil outlet. As the ring beam 1 slides, the oil drips onto the friction surface of the ceramsite, reducing the coefficient of friction and, in turn, the sliding resistance. Furthermore, the vibration of the ceramsite layer caused by earthquakes helps the oil penetrate and distribute better to the contact points between the ceramsite, achieving more uniform lubrication.

[0039] Example 2:

[0040] The oil-spraying lubrication of the oil tank 4 mentioned in the previous embodiment involves the rubber stopper falling, causing the oil in the oil tank 4 to flow out. However, when the ring beam 1 moves to the point of contact with the rubber pier 3, it may not move back. At this time, the oil flow can only lubricate the third ceramsite layer 23 in the area near the rubber pier 3, and cannot provide oil-spraying lubrication for the remaining ceramsite layers. Furthermore, because the oil in the oil tank 4 flows naturally, without a buffering or delay effect, the oil may flow out too quickly, resulting in poor lubrication of the ceramsite layer in the slip zone 2. Therefore, this embodiment further improves the oil tank 4 in Example 1.

[0041] See also Figure 2The difference between this embodiment and the previous embodiment is that the oil tank 4 is not provided with a rubber stopper. The oil tank 4 includes a first oil tank 41, which is provided with a one-way valve 42. The first oil tank 41 is made of an air bag or other flexible material and is filled with organic oil. A second oil tank 43 is provided on the left side of the first oil tank 41. The second oil tank 43 is connected to the first oil tank 41 through the one-way valve 42. A baffle 44 and a piston 45 are provided in the second oil tank 43. A slide matching the piston 45 is provided in the second oil tank 43. The piston 45 is slidably connected to the slide to provide positioning and guidance for the up and down movement of the piston 45, thereby preventing the piston 45 from dislocating during the movement process. The piston 45 is slidably connected to the inner wall of the second oil tank 43. The piston 45 is connected to a spring. The free end of the spring is linked to the baffle 44. The one-way valve 42 is provided on the baffle. 44 and the piston 45 enclosed in a hollow chamber formed; the baffle 44 is penetrated by an oil outlet pipe 46, and the oil outlet pipe 46 is rotatably connected to the baffle 44, the oil inlet end of the oil outlet pipe 46 is arranged between the baffle 44 and the piston 45, and the oil outlet end is arranged outside the second oil tank 43, the oil outlet end of the oil outlet pipe 46 is symmetrically provided with an inclined oil injection pipe 410, the oil injection pipe 410 is communicated with the oil outlet pipe 46, a section of the oil outlet pipe 46 located between the baffle 44 and the piston 45 is provided with a blade 49, the oil inlet end of the oil outlet pipe 46 is smaller than the oil outlet end of the oil outlet pipe 46, and a ball valve 47 is provided in the oil outlet pipe 46, the diameter of the ball valve 47 is larger than the diameter of the oil inlet end and smaller than the diameter of the oil outlet end, the ball valve 47 is connected to an elastic rope 48, and the free end of the elastic rope 48 is connected to the piston 45.

[0042] When the ring beam 1 slips, causing the first oil tank 41 to collide with the rubber pier 3, the first oil tank 41 deforms, generating pressure inside the first oil tank 41, which pushes the engine oil out of the one-way valve 42. The oil flows into the chamber enclosed by the baffle 44, the inner wall of the second oil tank 43, and the piston 45. As the amount of oil flowing in increases, it pushes the piston 45 upward and stretches the spring. The upward movement of the piston 45 drives the ball valve 47 via the elastic rope 48, causing the ball valve 47 to move, sealing the oil inlet end of the oil outlet pipe 46, thereby preventing the oil from flowing out of the chamber. When the first oil tank 41 is no longer squeezed, the piston 45 returns to its original position under the drive of the spring, and the elastic rope 48 drives the ball valve 47 to return to its original position, connecting the oil outlet pipe 46 to the enclosed chamber, and the engine oil now flows out. At the same time, after the oil in the enclosed chamber is squeezed, the blades 49 begin to rotate, so that the oil flowing out through the oil outlet pipe 46 is sprayed around the ceramsite layer under the action of centrifugal force. When the oil flows to the inclined oil injection pipe 410, the flow direction of the oil forms a certain angle with the oil outlet pipe 46, generating an additional component force along the outlet direction of the oil injection pipe 410. Under the action of centrifugal force, this component force causes the oil to be sprayed at a wider projection angle, thereby increasing the flight distance of the oil and enabling the oil to cover a farther area of ​​the ceramsite layer.

[0043] Example 3:

[0044] In the previous embodiments (Example 1 and Example 2), the sliding isolation device is installed at the bottom of the ring beam 1, and the ring beam 1 is a convex ring beam 1. The difference between this embodiment and the previous embodiment is that the sliding isolation device is installed at the bottom of the load-bearing column, forming a sliding isolation unit under the column.

[0045] The above is only an embodiment of the present invention, and the common knowledge such as the specific structure and characteristics of the scheme is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A variable friction coefficient sliding isolation device with a limit, comprising a ring beam (1), wherein a sliding area (2) is provided at the bottom of the ring beam (1), characterized in that: The slip zone (2) comprises: A first ceramsite layer (21), the first ceramsite layer (21) being arranged at the bottom of the ring beam (1); a second ceramsite layer (22), the second ceramsite layer (22) being symmetrically arranged on both sides of the first ceramsite layer (21), and the particle size of the second ceramsite layer (22) being smaller than that of the first ceramsite layer (21); a third ceramsite layer (23), the third ceramsite layer (23) being symmetrically arranged on both sides of the second ceramsite layer (22), the particle size of the third ceramsite layer (23) being smaller than that of the second ceramsite layer (22); and further comprising a rubber pier (3) arranged outside the third ceramsite layer (23); It also includes an oil tank (4) provided on the ring beam (1); the oil tank (4) includes a first oil tank (41), the first oil tank (41) is provided with a one-way valve (42), the first oil tank (41) is made of a flexible material, and the first oil tank (41) is provided in conjunction with the rubber pier (3); The second oil tank (43) is further provided with a second oil tank (43), the second oil tank (43) being connected to the first oil tank (41) via a one-way valve (42), a baffle (44) and a piston (45) being provided in the second oil tank (43), the piston (45) being slidably connected to the inner wall of the second oil tank (43), the piston (45) being connected to a spring, the free end of the spring being connected to the baffle (44), the one-way valve (42) being provided between the baffle (44) and the piston (45), the second oil tank (43) being provided with an oil outlet, an oil outlet pipe (46) being provided through the baffle (44), the oil inlet end of the oil outlet pipe (46) being provided between the baffle (44) and the piston (45), and the oil outlet end being provided at the second oil tank ( 43), the oil inlet end of the oil outlet pipe (46) is smaller than the oil outlet end of the oil outlet pipe (46), a ball valve (47) is provided in the oil outlet pipe (46), the diameter of the ball valve (47) is larger than the diameter of the oil inlet end and smaller than the diameter of the oil outlet end, the ball valve (47) is connected to an elastic rope (48), the free end of the elastic rope (48) is connected to the piston (45); the oil outlet pipe (46) is rotatably connected to the baffle (44), and a section of the oil outlet pipe (46) located between the baffle (44) and the piston (45) is provided with a blade (49); the oil outlet end of the oil outlet pipe (46) is provided with an inclined oil injection pipe (410), and the oil injection pipe (410) is communicated with the oil outlet pipe (46).

2. The variable friction coefficient sliding isolation device with limiter according to claim 1, characterized in that: A partition is provided between the first ceramsite layer (21), the second ceramsite layer (22) and the third ceramsite layer (23).

3. The variable friction coefficient sliding isolation device with limiter according to claim 1, characterized in that: A slide groove is provided in the second oil tank (43), and the piston (45) is slidably connected to the slide groove.

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