Anti-scouring structure suitable for sandy soil roadbed slope in construction period and protection method
By using used tire diversion mesh troughs transformed on high steep slopes of sandy soil roadbeds, combined with the layout of rapid flow troughs and drainage troughs, the problem of poor slope protection is solved, and the stability of the slope and the effective utilization of resources are achieved.
Patent Information
- Application Number
- CN202510335785.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-20
- Publication Date
- 2025-06-17
AI Technical Summary
On high steep slopes of sandy soil roadbeds, existing rapid troughs and concrete skeleton protection methods are prone to soil accumulation and soil erosion when the rainfall is high, resulting in unstable slopes and increasing protection costs.
Waste tires are transformed into tire diversion grid troughs, combining the layout of rapid flow troughs, diversion troughs and drainage troughs to form a complete drainage path, and grass seeds and shrub vegetation are planted between the tire diversion grid troughs to consolidate soil.
It effectively reduces the number of excavation and maintenance costs of rapid flow troughs, enhances the stability of the slope, reduces the risk of soil erosion, and realizes the secondary utilization of resources and beautification of the environment.
Smart Images
Figure CN120159079A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of slope protection, and particularly relates to an anti-erosion structure and a protection method suitable for sandy soil subgrade slopes during the construction period. Background Art
[0002] A slope is a slope with a certain gradient formed on both sides of the subgrade to ensure the stability of the subgrade. Slopes can be classified into artificial slopes and natural slopes according to their causes. In the field of highway construction, sandy soil has significant advantages such as good drainage, light weight, strong improvement, and renewable utilization, so it is widely used in highway subgrade construction.
[0003] However, the construction of sandy soil subgrades faces challenges such as a large amount of earthwork and a long cycle. Especially when the slope gradient is large, the problem is more prominent. On high and steep slopes, the adhesion and anti-erosion ability of the slope surface itself are weak. Currently, the conventional protection method is to set up chute drains and use concrete skeletons combined with herbaceous vegetation planted around the skeletons to fix the soil. However, when the rainfall is large, a large amount of soil will be carried along during the drainage process of the chute drains, and these soils are easily accumulated in the troughs and at the bottom of the slopes, seriously affecting the smoothness of subsequent drainage. At the same time, even relying on the support of concrete skeletons and the rooting of vegetation to fix the soil, it is still difficult to effectively prevent the large amount of soil loss on the slopes, which will pose a threat to the safety of the construction of the sandy soil subgrade above the slopes. Repeated reinforcement and replacement to solve these problems will undoubtedly further increase the cost of slope protection. Therefore, it is urgent to develop a more efficient, stable and economical protection scheme for high and steep slopes of sandy soil subgrades to improve the quality and safety of highway construction. Summary of the Invention
[0004] Aiming at the technical problem of poor anti-erosion effect after setting up chute drains and concrete skeletons on the high and steep slopes of sandy soil roads, the present invention provides an anti-erosion structure and a protection method suitable for sandy soil subgrade slopes during the construction period. By recycling waste tires, the slope is reinforced and diverted, reducing the number of chute drains dug and the maintenance cost, and also reducing the construction and maintenance costs of setting up concrete skeletons on the slopes.
[0005] The technical solution of the present invention is as follows: In the first aspect, the present invention provides an anti-erosion structure suitable for sandy soil subgrade slopes during the construction period, including a plurality of chute drains arranged on the sandy soil subgrade slopes. The distance between adjacent chute drains is 50 - 80 m. One end of the chute drain is connected to the diversion trough at the edge of the sandy soil subgrade, and the other end is connected to the drainage ditch at the bottom of the slope. Both the diversion trough and the drainage ditch are in the same direction as the sandy soil subgrade; Lay a tire diversion net groove on the slope between the chute; the tire diversion net groove is composed of several half-tires arranged in layers. The half-tire is a tire cut into a U-shape. Except for the bottom half-tire, a water leakage hole is dug on the lower wall of the bottom of each half-tire, and one end of the next layer of half-tire is docked below the water leakage hole; both ends of the top half-tire are docked with the second drainage openings on the side wall of the diversion groove, and the water leakage holes of the bottom half-tire are arranged on the bottom side wall; when the slope position close to the chute is not enough to arrange a whole half-tire, it is supplemented with 1 / 2 of a half-tire; Plant and lay grass seeds and shrub vegetation in the gaps of the tire diversion net groove.
[0006] Further, the inclination angle of the sandy soil subgrade slope is 45°-60°.
[0007] Further, there is also a road shoulder adjacent to the diversion groove on the sandy soil subgrade. The height of the road shoulder is 15-20 cm. A plurality of uniformly distributed first drainage openings are opened at the connection between the road shoulder and the sandy soil subgrade, and the first drainage openings lead to the diversion groove; a filter screen is arranged on the first drainage openings.
[0008] Further, the half-tires are fixed on the slope by cross nails; according to the arrangement firmness of the half-tires, one or several cross nails are selected to fix each half-tire, or in a plurality of adjacent half-tires, one half-tire is selected to be fixed with one or several cross nails.
[0009] Further, the chute is covered with a top cover, and the top cover is composed of a plurality of top cover components spliced together. An adjacent top cover component forms a water permeable hole at the splicing position.
[0010] Setting the top cover can prevent sundries from entering the chute and causing blockage, and to a certain extent protect the chute structure from being damaged by external factors. The existence of the water permeable hole is convenient for the operator to assemble and also facilitates rainwater to enter the chute.
[0011] Further, except for the bottom half-tire, two water leakage holes are dug at the bottom of each half-tire, which are respectively docked with one end of two adjacent half-tires in the next layer.
[0012] Further, a revetment road is arranged between the slope and the drainage ditch. A branch groove connecting to the water leakage hole of the bottom half-tire is dug on the revetment road, and the other end of the branch groove is connected to the drainage ditch.
[0013] Further, the grass seeds are at least one of ryegrass, poa annua and tall fescue; the shrub vegetation is at least one of lespedeza bicolor and amorpha fruticosa.
[0014] In a second aspect, the present invention provides a protection method applicable to the slope of a sandy soil subgrade during the construction period, including the following steps: Step 1: Dig diversion channels along the edge of the sandy soil subgrade. Mix the soil dug from the diversion channels with concrete and pile it up to form a road shoulder along the edge on the side of the diversion channel away from the slope. Dig a plurality of first drainage holes at the bottom of the road shoulder and cover the first drainage holes with filter meshes. Use concrete to raise the side wall of the diversion channel on the side close to the slope, and set second drainage holes for docking semi-tires on the raised side wall of the diversion channel. Step 2: Dig a drainage ditch parallel to the sandy soil subgrade at the bottom of the slope of the sandy soil subgrade. Step 3: Uniformly dig a plurality of chute channels on the slope of the sandy soil subgrade. Mix the soil dug from the chute channels with concrete and use it to raise the side walls on both sides of the chute channels. One end of the chute channel is connected to the diversion channel, and the other end is connected to the drainage ditch. Lay a top cover assembly on the chute channel in sequence. Step 4: Arrange a number of semi-tires layer by layer on the slope between the chute channels to form a tire diversion network channel. When the slope position close to the chute channel is not enough to arrange a whole semi-tire, use 1 / 2 of a semi-tire to make up. The two ends of the top-layer semi-tires are docked with the second drainage holes one by one. Except for the bottom-layer semi-tires, the two water leakage holes on the lower wall of the bottom of each upper-layer semi-tire are respectively docked with one end of two adjacent semi-tires in the lower layer. The bottom-layer semi-tires are in contact with the bottom of the slope, and the water flowing out of the water leakage holes of the bottom-layer semi-tires leads to the drainage ditch.
[0015] Further, in Step 4, leave a flat area at the bottom of the slope to form a berm. Dig a branch channel leading to the drainage ditch below the water leakage holes dug on the side wall of the bottom of the bottom-layer semi-tires.
[0016] The beneficial effects of the present invention are as follows: (1) Cost control and resource utilization: Innovatively utilize waste tires and transform them into tire diversion network channels, which not only realizes the secondary utilization of resources, conforms to the environmental protection concept, but also greatly reduces the excavation quantity of chute channels, reduces the maintenance cost of chute channels, and at the same time reduces the cost of setting concrete skeletons on the slope, achieving a win-win situation of economic and environmental benefits.
[0017] (2) Slope protection and drainage optimization: Through the reasonable layout of chute channels, diversion channels and drainage ditches, a perfect and smooth drainage path is formed. The chute channels connect the diversion channels and the drainage ditches, and can quickly drain the rainwater on the slope, which finally flows into the drainage ditch, effectively avoiding the long-term scouring of the slope by water flow. The tire diversion network channel is composed of semi-tires arranged layer by layer, and this structure is like putting "armor" on the slope, enhancing the stability of the slope soil body and reducing the risk of soil erosion.
[0018] (3) Ecological protection and environmental beautification: Uniformly lay grass seeds and shrub vegetation between the tire diversion network channels, which can not only strengthen soil fixation by the vegetation roots and further improve the anti-scouring ability, but also add green vitality to the slope, beautify the surrounding environment, and promote the healthy development of the ecosystem. Description of the Drawings
[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0020] Figure 1 is the front view of the anti-erosion structure of the sandy soil subgrade slope during the construction period of the present invention.
[0021] Figure 2 is the cross-sectional view of the anti-erosion structure of the sandy soil subgrade slope in Embodiment 1 of the present invention.
[0022] Figure 3 is the cross-sectional view of the anti-erosion structure of the sandy soil subgrade slope in Embodiment 2 of the present invention.
[0023] In the figure, 1 - road shoulder, 2 - chute, 3 - top cover assembly, 4 - permeable hole, 5 - tire diversion net groove, 6 - leakage hole, 7 - diversion groove, 8 - cross nail, 9 - drainage ditch, 10 - berm. Specific embodiments
[0024] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.
[0025] Embodiment 1 An anti-erosion structure applicable to a sandy soil subgrade slope with an inclination angle of 45° during the construction period, including a plurality of chutes 2 arranged on the sandy soil subgrade slope. The chutes 2 are covered with a top cover, and the top cover is composed of a plurality of top cover assemblies 3 spliced together. Adjacent top cover assemblies 3 form a permeable hole 4 at the splicing position. The interval distance between adjacent chutes 2 is 50 m. One end of the chute 2 is connected to the diversion groove 7 at the edge of the sandy soil subgrade, and the other end is connected to the drainage ditch 9 at the bottom of the slope. The diversion groove 7 and the drainage ditch 9 are both in the same direction as the sandy soil subgrade; There is also a road shoulder 1 adjacent to the diversion groove 7 on the sandy soil subgrade. The height of the road shoulder 1 is 15 cm. A plurality of uniformly distributed first drainage openings are opened at the connection between the road shoulder 1 and the sandy soil subgrade. The first drainage openings lead to the diversion groove 7, and a filter screen is arranged on the first drainage openings; Lay a tire diversion net groove 5 on the slope between the chute 2; the tire diversion net groove 5 is composed of a number of half-tires arranged in layers. The half-tire is a tire cut into a U-shape. When the slope position near the chute 2 is not enough to arrange a whole half-tire, it is supplemented with 1 / 2 of a half-tire. The half-tires are fixed to the slope by cross nails 8, and each half-tire is fixed with one cross nail 8; except for the bottom half-tires, two water leakage holes 6 are dug on the bottom wall of each half-tire, and are respectively butted with one end of two adjacent half-tires in the next layer; both ends of the top half-tire are butted with the second drainage ports on the side walls of the diversion groove 7, and the water leakage holes 6 of the bottom half-tires are arranged on the bottom side walls. Evenly plant ryegrass, Kentucky bluegrass and lespedeza in the gaps of the tire diversion net groove 5.
[0026] The tire diversion net groove 5 laid on the sandy soil subgrade slope and the vegetation planted in the gaps of the tire diversion net groove 5 interact with each other to jointly play a role in fixing the slope and preventing soil erosion. When it rains, the water on the sandy soil subgrade flows through the first drainage port set on the road shoulder 1 to the diversion groove 7. The filter screen set on the diversion groove 7 can intercept sundries to facilitate the smooth discharge of water flow. A part of the water in the diversion groove 7 flows through the second drainage port to the tire diversion net groove 5, and the water flow curves and flows in the inner walls of multiple half-tires and finally flows to the drainage ditch 9; another part of the water enters the chute 2 and then directly flows to the drainage ditch 9. The use of the tire diversion net groove 5 reduces the discharge pressure and maintenance cost of the chute 2.
[0027] Embodiment 2 An anti-scouring structure suitable for the construction period sandy soil subgrade slope with an inclination angle of 60° includes a number of chutes 2 arranged on the sandy soil subgrade slope. The chutes 2 are covered with a top cover. The top cover is composed of multiple top cover components 3 spliced together. Adjacent top cover components 3 form a water permeable hole 4 at the splicing position. The interval distance between adjacent chutes 2 is 80m. One end of the chute 2 is connected to the diversion groove 7 at the edge of the sandy soil subgrade. After passing through the slope protection road 10 arranged between the slope and the drainage ditch 9 at the other end of the chute 2, it is connected to the drainage ditch 9. The diversion groove 7 and the drainage ditch 9 are both in the same direction as the sandy soil subgrade. There is also a road shoulder 1 adjacent to the diversion groove 7 on the sandy soil subgrade. The height of the road shoulder 1 is 20cm. A number of evenly distributed first drainage ports are opened at the connection between the road shoulder 1 and the sandy soil subgrade. The first drainage ports lead to the diversion groove 7, and filter screens are set on the first drainage ports. Lay a tire diversion net groove 5 on the slope between the chute 2s; the tire diversion net groove 5 is composed of a number of half-tires arranged in layers. The half-tire is a tire cut into a U shape. When the slope position near the chute 2 is not sufficient to arrange a whole half-tire, it is supplemented with 1 / 2 of a half-tire. The half-tires are fixed to the slope with cross nails 8, and each half-tire is fixed with three cross nails 8; except for the bottom layer of half-tires, two water leakage holes 6 are dug in the bottom lower wall of each half-tire, and are respectively butted with one end of two adjacent half-tires in the next layer; the two ends of the top layer of half-tires are butted with the second drainage openings on the side walls of the diversion groove 7, and the water leakage holes 6 of the bottom layer of half-tires are arranged on the bottom side walls. A tributary groove for butting the water leakage holes 6 of the bottom layer of half-tires is dug on the berm 10, and the other end of the tributary groove is connected to the drainage ditch 9; Evenly plant tall fescue, Kentucky bluegrass and Amorpha fruticosa in the gaps of the tire diversion net groove 5.
[0028] Compared with Embodiment 1, in this embodiment, there is a berm 10 left between the bottom of the sandy soil subgrade slope and the drainage ditch 9, and a tributary groove connecting the tire diversion net groove 5 and the drainage ditch 9 is arranged on the berm 10. The setting of the berm 10 can, to a certain extent, increase the support area and weight at the bottom of the slope, reduce the direct scouring of the water flow on the slope toe and the drainage ditch, and contribute to improving the overall stability of the slope.
[0029] Embodiment 3 A protection method applicable to the slope of sandy soil subgrade during the construction period includes the following steps: Step 1: Dig a diversion groove along the edge of the sandy soil subgrade, mix the soil dug for the diversion groove with concrete, and pile it up into a road shoulder along the edge on the side of the diversion groove away from the slope. A plurality of first drainage openings are dug at the bottom of the road shoulder, and filter meshes are covered on the first drainage openings; Use concrete to raise the side wall of the diversion groove on the side close to the slope, and set second drainage holes for butting the half-tires on the raised side wall of the diversion groove; Step 2: Dig a drainage ditch parallel to the sandy soil subgrade at the bottom of the sandy soil subgrade slope; Step 3: Evenly dig a plurality of chute on the sandy soil subgrade slope. The soil dug for the chute is mixed with concrete and used to raise the side walls on both sides of the chute. One end of the chute is connected to the diversion groove, and the other end is connected to the drainage ditch. Cover plate assemblies are sequentially laid on the chute; Step 4: Arrange a number of half-tires in layers on the slope between the chute to form a tire diversion net groove. When the slope position near the chute is not sufficient to arrange a whole half-tire, it is supplemented with 1 / 2 of a half-tire; the two ends of the top layer of half-tires are butted with the second drainage holes one by one. Except for the bottom layer of half-tires, the two water leakage holes in the bottom lower wall of each half-tire in the upper layer are respectively butted with one end of two adjacent half-tires in the next layer; the bottom layer of half-tires is in contact with the bottom of the slope, and the water flowing out of the water leakage holes of the bottom layer of half-tires leads to the drainage ditch.
[0030] Example 4 A protection method applicable to sandy soil subgrade slopes during the construction period, comprising the following steps: Step 1: Dig diversion channels along the edge of the sandy soil subgrade. Mix the soil dug from the diversion channels with concrete and pile it up to form a road shoulder along the edge on the side of the diversion channel away from the slope. Dig a plurality of first drainage holes at the bottom of the road shoulder and cover the first drainage holes with filter meshes. Use concrete to raise the side wall of the diversion channel on the side close to the slope, and set second drainage holes for docking half-tires on the raised side wall of the diversion channel; Step 2: Dig a drainage ditch parallel to the sandy soil subgrade at the bottom of the sandy soil subgrade slope; Step 3: Uniformly dig a plurality of chute channels on the sandy soil subgrade slope. Mix the soil dug from the chute channels with concrete and use it to raise the side walls on both sides of the chute channels. One end of the chute channel is connected to the diversion channel, and the other end is connected to the drainage ditch. Lay a top cover assembly on the chute channel in sequence; Step 4: Arrange a number of half-tires in layers on the slope between the chute channels to form a tire diversion network channel. When the slope position close to the chute channel is not enough to arrange a whole half-tire, use 1 / 2 of a half-tire to make up. The two ends of the top-layer half-tires are docked with the second drainage holes one by one. Except for the bottom-layer half-tires, the two water leakage holes on the lower wall of the bottom of each half-tire in the upper layer are respectively docked with one end of two adjacent half-tires in the lower layer. The bottom-layer half-tires are in contact with the bottom of the slope, and a flat ground is left at the bottom of the slope to form a revetment road. Dig a branch channel leading to the drainage ditch below the water leakage holes dug on the side wall at the bottom of the bottom-layer half-tires, and the water flowing out of the water leakage holes of the bottom-layer half-tires leads to the drainage ditch.
[0031] Although the present invention has been described in detail by referring to the drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, those of ordinary skill in the art can make various equivalent modifications or substitutions to the embodiments of the present invention, and all such modifications or substitutions should be within the scope of the present invention. / Any person familiar with the technical field of the present invention can easily think of changes or substitutions within the technical scope disclosed by the present invention, and all should be covered within the protection scope of the present invention.
Claims
1. An anti-scour structure suitable for a sandy soil roadbed slope during construction, comprising a plurality of rapids troughs (2) arranged on the sandy soil roadbed slope, characterized in that: The interval between adjacent rapid flow troughs (2) is 50-80 m, one end of the rapid flow trough (2) is connected to the diversion trough (7) at the edge of the sandy soil roadbed, and the other end is connected to the drainage ditch (9) at the bottom of the slope, and the diversion trough (7) and the drainage ditch (9) are both in the same direction as the sandy soil roadbed; A tire diversion net trough (5) is laid on the side slope between the rapid flow troughs (2); the tire diversion net trough (5) is composed of a plurality of half tires arranged in layers, wherein the half tires are tires cut into a U shape, and except for the half tires on the bottom layer, a leakage hole (6) is dug on the bottom wall of each half tire, and the leakage hole (6) is connected to one end of the half tire on the next layer; both ends of the half tire on the top layer are connected to the second drainage port on the side wall of the diversion trough (7), and the leakage hole (6) of the half tire on the bottom layer is arranged on the bottom side wall; when the side slope position close to the rapid flow trough (2) is not enough to arrange a whole half tire, 1 / 2 half tire is used to make up for it; Grass seeds and shrubs are planted and laid in the gaps between the tire guide net grooves (5).
2. The anti-scour structure for sandy soil roadbed slopes during construction as claimed in claim 1, characterized in that: The inclination angle of the sandy soil roadbed slope is 45°-60°.
3. The anti-scour structure for sandy soil roadbed slopes during construction as claimed in claim 1, characterized in that: A shoulder (1) is arranged adjacent to the diversion trough (7) on the sandy soil roadbed. The height of the shoulder (1) is 15-20 cm. A plurality of evenly distributed first drainage outlets are provided at the connection between the shoulder (1) and the sandy soil roadbed. The first drainage outlets lead to the diversion trough (7). A filter screen is provided on the first drainage outlets.
4. The anti-scour structure for sandy soil roadbed slopes during construction as claimed in claim 1, characterized in that: The half tires are fixed on the slope by cross nails (8); according to the firmness of the arrangement of the half tires, each half tire is selected to be fixed with one or several cross nails (8), or one half tire is selected from a plurality of adjacent half tires to be fixed with one or several cross nails (8).
5. The anti-scour structure for sandy soil roadbed slopes during construction as claimed in claim 1, characterized in that: The rapid flow trough (2) is covered with a top cover, which is formed by splicing a plurality of top cover components (3), and adjacent top cover components (3) form a water permeable hole (4) at the splicing position.
6. The anti-scour structure for sandy soil roadbed slopes during construction as claimed in claim 1, characterized in that: Except for the bottom half tire, two water leakage holes (6) are dug at the bottom of each half tire, which are respectively connected to one end of two adjacent half tires in the next layer.
7. The anti-scour structure for sandy soil roadbed slopes during construction as claimed in claim 1, characterized in that: A slope protection road (10) is arranged between the side slope and the drainage ditch (9), and a branch trough for connecting with the bottom half tire water leakage hole (6) is dug on the slope protection road (10), and the other end of the branch trough is connected to the drainage ditch (9).
8. The anti-scour structure for sandy soil roadbed slopes during construction as claimed in claim 1, characterized in that: The grass seeds are at least one of ryegrass, bluegrass and tall fescue; the shrub vegetation is at least one of Lespedeza and Amorpha fruticosa.
9. A protection method for sandy soil roadbed slopes during construction, characterized in that: The steps include: Step 1: digging a diversion trough (7) along the edge of a sandy soil roadbed, mixing the soil excavated from the diversion trough (7) with concrete, and piling the soil along the edge of the diversion trough (7) away from the side slope to form a shoulder (1), digging a plurality of first drainage outlets at the bottom of the shoulder (1), and covering the first drainage outlets with a filter screen; using concrete to raise the side wall of the diversion trough (7) close to the side slope, and providing a second drainage hole for docking the half tire on the raised side wall of the diversion trough (7); Step 2: digging a drainage ditch (9) at the bottom of the sandy soil roadbed slope in the same direction as the sandy soil roadbed; Step 3: a plurality of rapid flow grooves (2) are evenly excavated on the sandy soil roadbed slope, the soil excavated from the rapid flow grooves (2) is mixed with concrete and used to raise the side walls of both sides of the rapid flow grooves (2), one end of the rapid flow groove (2) is connected to the guide groove (7), and the other end is connected to the drainage ditch (9), and the top cover assembly (3) is laid on the rapid flow groove (2) in sequence; Step 4: a plurality of half tires are arranged layer by layer on the slope between the rapid flow grooves (2) to form a tire diversion network groove (5). When the slope position close to the rapid flow groove (2) is insufficient to arrange a whole half tire, 1 / 2 half tire is used to make up for it; both ends of the top half tire are connected to the second drainage holes one by one, and except for the bottom half tire, the two leakage holes (6) on the bottom wall of each half tire of the upper layer are respectively connected to one end of two adjacent half tires of the lower layer; the bottom half tire is in contact with the bottom of the slope, and the water flowing out of the leakage holes (6) of the bottom half tire is led to the drainage ditch (9).
10. A protection method for sandy soil roadbed slopes during construction as claimed in claim 9, characterized in that: In step 4, a flat area is left at the bottom of the slope to form a slope protection road (10), and a branch trough leading to the drainage ditch (9) is dug below the leakage hole (6) dug on the bottom side wall of the bottom half tire.