CN211872410U

CN211872410U - Water-proof and drainage structure of ballastless track roadbed

Info

Publication number: CN211872410U
Application number: CN201921768061.7U
Authority: CN
Inventors: 陈占; 何新辉; 彭志鹏; 陈仕奇; 操鹏; 李丹; 曾国升; 赵勇; 孟长江; 崔国庆
Original assignee: China Railway Siyuan Survey and Design Group Co Ltd; China Railway Siyuan Group Engineering Construction Co Ltd
Current assignee: China Railway Siyuan Survey and Design Group Co Ltd; China Railway Siyuan Group Engineering Construction Co Ltd
Priority date: 2019-10-21
Filing date: 2019-10-21
Publication date: 2020-11-06
Anticipated expiration: 2029-10-21

Abstract

The application provides a drainage structures of preventing of ballastless track road bed, drainage structures includes: the water collecting well is arranged in an inter-line area of the two ballastless tracks; the drainage assembly is arranged in the bed bottom layer of the roadbed and communicated with the water collecting well so as to drain liquid in the water collecting well out of the ballastless track; the first sealing layer is arranged on the surface layer of the foundation bed of the roadbed, avoiding the water collecting well in the inter-line area, and the height of the first sealing layer is lower than that of the supporting layer of the ballastless track. The utility model provides a prevent drainage structures collects the liquid of ballastless track in and peripheral region to the sump pit, outside the liquid discharge ballastless track in with the sump pit through the drainage subassembly, avoids liquid to stay at ballastless track long-pending, and the drainage is rapid, and drainage effect is good.

Description

Water-proof and drainage structure of ballastless track roadbed

Technical Field

The application relates to the field of geotechnical engineering, in particular to a waterproof and drainage structure of a ballastless track roadbed.

Background

Referring to fig. 1, the conventional ballastless track 100 ' includes a support layer 110 ' and a track slab 120 ' located above the support layer 110 ', and a roadbed waterproof and drainage structure of the ballastless track 100 ' includes a high-closure waterproof and drainage structure, and the line high-closure waterproof and drainage structure includes: the graded crushed stone layer 1 'arranged above the foundation bed 200' in the area between the ballastless tracks 100 'and the sealing layer 2' arranged above the graded crushed stone layer 1 ', the height of the sealing layer 2' is higher than that of the track slab 120 ', and by the design, water liquid in the area between the tracks is transversely discharged from the upper surface of the sealing layer 2', and due to poor drainage effect, normal operation of high-speed rails is seriously affected, and hidden troubles are brought to safe operation of the high-speed rails.

Disclosure of Invention

In view of this, the embodiment of the present application is expected to provide a waterproof and drainage structure for a ballastless track subgrade, which solves the technical problem that the existing ballastless track subgrade highly-closed waterproof and drainage structure has a poor drainage effect, and in order to solve the technical problem, the technical scheme of the embodiment of the present application is implemented as follows:

the embodiment of the application provides a drainage structures of ballastless track road bed, drainage structures includes:

the water collecting well is arranged in an inter-line area of the two ballastless tracks;

the drainage assembly is arranged in the bed bottom layer of the roadbed and communicated with the water collecting well so as to discharge liquid in the water collecting well out of the ballastless track;

the first sealing layer is arranged on the surface layer of the foundation bed of the roadbed, avoiding the water collecting well in the inter-line area, and the height of the first sealing layer is lower than that of the supporting layer of the ballastless track.

Further, the drainage assembly comprises a sleeve and a drainage pipe sleeved in the sleeve.

Furthermore, the side wall of the sleeve is provided with a slurry leakage hole.

Further, the drain assembly includes a bracket disposed between the sleeve and the drain pipe, the bracket for spacing the sleeve from the drain pipe.

Further, the bracket is arranged between the sleeve and the drain pipe at intervals;

and/or the length of the sleeve is 40 cm-60 cm.

Further, the drainage structures comprise ditches arranged in the inter-line areas, and the ditches are communicated with two adjacent water collecting wells.

Furthermore, the ditch is a longitudinal slope of 0.1-0.5%.

Further, the waterproof and drainage structure comprises a second sealing layer arranged on the ballastless track shoulder, and the height of the second sealing layer is lower than that of the supporting layer.

Further, the second sealing layer is 3% -6% of a cross slope.

Further, an end of the first sealing layer adjacent to the support layer is higher than an end of the first sealing layer adjacent to the gutter.

The utility model provides a ballastless track subgrade prevent drainage structures collects ballastless track interior and peripheral region's liquid to the sump pit, outside the ballastless track of liquid discharge in with the sump pit through the drainage subassembly, avoids liquid to stay in ballastless track, and the drainage is rapid, and drainage effect is good. The first seal prevents the infiltration of liquids through the earth's surface into the subgrade. Because the height of the first sealing layer is lower than that of the supporting layer of the ballastless track, the defects of gap, white slurry emission, slurry leakage and mud emission of the surface layer of the foundation bed and the like at the junction of the supporting layer and the track slab can be conveniently found in time, and the treatment is easy.

Drawings

Fig. 1 is a schematic cross-sectional view of a waterproof and drainage structure of a ballastless track subgrade in the prior art;

fig. 2 is a schematic cross-sectional view of a waterproof and drainage structure of a ballastless track subgrade in the practice of the present application;

figure 3 is a cross-sectional view of a drainage assembly in the bottom layer of a foundation bed in an embodiment of the present application.

Reference numerals: a ballastless track 100; a support layer 110; a track plate 120; a bed bottom layer 210; a bed skin 220; a water collection well 10; a drain assembly 20; a sleeve 21; a drain pipe 22; a bracket 23; a first sealing layer 30; a gutter 40; a second sealing layer 50; a working well 300; a grouting hole 400; and an exhaust hole 500.

Detailed Description

The present application will now be described in further detail with reference to the accompanying drawings and specific examples. "interline area" refers to the area between two ballastless tracks, "cross slope" refers to the lateral gradient of each component of ballastless track roadways and roadside belts, "longitudinal slope" refers to the longitudinal gradient of ballastless track in the extending direction, "up" and "down" orientation or position relationship is based on the normal use state of ballastless tracks, such as the orientation or position relationship shown in fig. 2, "cm" refers to international unit centimeter, it should be understood that these orientation terms are only used for convenience of describing and simplifying the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore, should not be understood as limiting the present invention.

Referring to fig. 2, an embodiment of the present application provides a waterproof and drainage structure for a ballastless track subgrade, including:

the water collecting well 10 is arranged in an inter-line area of the two ballastless tracks 100;

the drainage assembly 20 is arranged in the foundation bed bottom layer 210 of the roadbed and communicated with the water collecting well 10 so as to drain liquid in the water collecting well 10 out of the ballastless track 100;

the first sealing layer 30 is arranged on the surface layer 220 of the foundation bed of the water collecting well 10 in the inter-line area, and the height of the first sealing layer 30 is lower than that of the supporting layer 110 of the ballastless track 100.

In the prior art, a ballastless track adopts a highly-closed drainage structure, referring to fig. 1, serious diseases such as slurry pumping between a closed layer 2 'and a track plate 120', mortar precipitation between the track plate 120 'and a supporting layer 110', damage and crack separation of a mortar layer (not shown) and the like often occur, and the reason of the disease is often difficult to find after the disease occurs, so that the renovation is difficult. The reason for this is that rainwater easily enters the sealing layer 2 ' due to unsmooth drainage of the high-sealing drainage structure, and since the sealing layer 2 ' is higher than the track plate 120 ', small diseases generated in a short time often cannot be found through line investigation, so that serious water accumulation in the sealing layer 2 ' gradually causes serious diseases such as grout stirring and mud pumping between the sealing layer 2 ' and the track plate 120 ', mortar separation between the track plate 120 ' and the supporting layer 110 ', mortar layer damage and crack separation and the like under the impact vibration of high-speed loads of trains, and on the other hand, due to the overhigh height of the sealing layer 2 ', the diseases are not easy to be remedied.

The utility model provides a waterproof and drainage structure of ballastless track road bed, road bed include foundation bed top layer 220 and foundation bed bottom 210, and foundation bed top layer 220 bears the dynamic stress that the train load produced great, sets up drainage component 20 and is favorable to keeping drainage component 20's structural stability at foundation bed bottom 210, also is favorable to keeping the structural stability of road bed. In addition, in some embodiments, the foundation bed surface layer 220 includes graded broken stones, in which case, since the graded broken stones have greater strength, the drainage assembly 20 is disposed on the foundation bed bottom layer 210, and the drainage assembly 20 can be rapidly disposed into the foundation bed bottom layer 210 without damaging the original ballastless track 100, which facilitates construction. Liquid in the ballastless track 100 and in the peripheral area is collected to the water collecting well 10, the liquid in the water collecting well 10 is discharged out of the ballastless track 100 through the drainage assembly 20, the liquid is prevented from being accumulated on the ballastless track 100, drainage is rapid, and the drainage effect is good. The first sealing layer 30 prevents liquid from penetrating into the roadbed through the earth surface, thereby avoiding serious diseases such as slurry pumping between the first sealing layer 30 and the track plate 120, mortar separation between the track plate 120 and the supporting layer 110, mortar layer damage and crack separation. On the other hand, the height of the first sealing layer 30 is lower than that of the supporting layer 110 of the ballastless track 100, so that whether the joint between the supporting layer 110 and the track slab 120 has the defects of gap, white slurry leakage, slurry overflow and mud leakage of the surface layer of the foundation bed, and the like, can be found in time, and the treatment is easy. It will be appreciated that the caulk between the first closure layer 30 and the support layer 110 needs to be sealed to avoid liquid infiltration of the caulk between the first closure layer 30 and the support layer 110.

If the waterproof and drainage structure of the ballastless track subgrade provided by the embodiment of the application is arranged on the existing ballastless track, the electric pick or the air compressor matched air pick can be adopted to chisel the sealing layer and the graded broken stone layer in the inter-line area, the cutting machine can be adopted to cut the thicker part of the sealing layer into blocks and then chisel the thicker part, and the output line is transported through a flat car or a trolley. Of course, if the waterproof and drainage structure of the ballastless track subgrade provided by the embodiment of the application is arranged on the newly constructed ballastless track, the following construction steps can be directly implemented without the step.

Next, referring to fig. 2, a working well 300 is excavated in the inter-line area for subsequent construction operations. Transversely jacking the drainage assembly 20 into the foundation bed bottom layer 210 of the roadbed, specifically, transversely jacking the drainage assembly 20 into the foundation bed bottom layer 210 from the working well 300 by using micro pipe jacking equipment, or jacking the drainage assembly 20 into the foundation bed bottom layer 210 from one side of the foundation bed bottom layer 210 far away from the inter-line area by using the micro pipe jacking equipment; then, the gap around the drain assembly 20 is filled to prevent the gap around the drain assembly 20 from being a flow channel for the groundwater and other liquids, and to stabilize the drain assembly 20.

Then, the water collecting well 10 is arranged in the working well 300, the water collecting well 10 can be cast in situ by adopting a template containing reinforcing steel bars, or can be prefabricated in advance, and the construction time can be saved by adopting the water collecting well 10 prefabricated in advance. The drainage assembly 20 is communicated with the water collecting well 10, so that a water outlet (not shown) communicated with the drainage assembly 20 can be reserved in the manufacturing process of the water collecting well 10, a water outlet can be formed in the water collecting well 10 after the water collecting well 10 is manufactured, liquid in the water collecting well 10 is discharged out of the ballastless track 100 from the drainage assembly 20 through the water outlet, and the liquid is prevented from being accumulated on the ballastless track 100 to affect the safety of the ballastless track 100.

And thirdly, concrete is poured on the surface layer 220 of the foundation bed of the roadbed avoiding the water collecting well 10 in the inter-line area to form a first closed layer 30, and the first closed layer 30 plays a waterproof role and prevents liquid from the ballastless track 100 from permeating into the roadbed. The height of the first sealing layer 30 is lower than that of the supporting layer 110 of the ballastless track 100, so that liquid of the ballastless track 100 is collected to the water collection well 10 and discharged through the water collection well 10. Specifically, the first sealing layer 30 is formed by pouring fiber concrete.

Finally, sealing the caulk between the first closure layer 30 and the support layer 110 includes: the caulking joint between the first sealing layer 30 and the supporting layer 110 is cleaned, an antifouling adhesive tape is pasted on the adjacent area at the periphery of the caulking joint, the antifouling adhesive tape can be needless, the antifouling adhesive tape is used for preventing an interface agent and a sealing material from polluting the adjacent area at the periphery of the junction, the interface agent is coated on the surface of the caulking joint, the interface agent can be needless, the interface agent is used for improving the surface performance of the junction, the sealing effect of the sealing material is better realized, the caulking joint is filled with a filler, the filler is a material with a waterproof sealing effect, such as a silicone sealant or a polyurethane sealant, liquid is prevented from entering the first sealing layer 30, the supporting layer 110 and/or a roadbed from the caulking joint, and the antifouling adhesive tape is dismantled.

The construction method for constructing the water-proof and drainage knot of the ballastless track subgrade of the embodiment of the application through the construction steps is simple, high in construction efficiency and short in construction period, and construction can be completed in a skylight period conveniently.

In one embodiment of the present application, referring to fig. 3, the drainage assembly 20 includes a casing 21 and a drainage pipe 22 sleeved in the casing 21. With this construction, the sleeve 21 serves to withstand the earth pressure, water pressure and road load from the subgrade, maintaining the structural rigidity of the drainage assembly 20. A drain pipe 22 for draining water is installed in the sleeve 21 so that the drain assembly 20 has a long lifespan. If the implementation method of transversely jacking the drainage assembly 20 into the foundation bed bottom layer 210 is adopted, the sleeve 21 with stronger stress capacity can be jacked into the foundation bed bottom layer 210 firstly by adopting the structure of the sleeve 21 and the drainage pipe 22 sleeved in the sleeve 21, and then the drainage pipe 22 is arranged in the sleeve 21. In one embodiment, the sleeve 21 may be a metal tube, such as a galvanized steel tube, a copper tube, etc., and has a strong structural strength to support not only compressive stress and bending moment, but also to laterally push the sleeve 21 into the bottom foundation layer 210. The drain pipe 22 may be an organic polymer pipe such as a polyvinyl chloride pipe, a polyethylene pipe, or a high-density polyethylene pipe, which is inexpensive to manufacture and has a long service life.

In an embodiment of the present application, referring to fig. 3, a slurry leaking hole (not shown) is formed on a side wall of the sleeve 21. The drainage assembly 20 is arranged in the foundation bed bottom layer 210 of the roadbed, and as the gaps at the periphery of the drainage assembly 20 need to be sealed and filled, slurry leakage holes are formed in the side wall of the sleeve 21, so that the gaps between the foundation bed bottom layer 210 and the sleeve 21 and between the sleeve 21 and the drainage pipe 22 can be filled conveniently. In the construction process of filling the grout, the grout can seal and fill the gaps at the periphery of the drainage assembly 20 through the grout leakage holes, and by the design, the grouting process is reduced, and the construction period is shortened.

In one embodiment of the present application, referring to fig. 3, the drain assembly includes a bracket 23 disposed between the sleeve 21 and the drain pipe 22, the bracket 23 being used to space the sleeve 21 from the drain pipe 22. By the design, the inner wall of the sleeve 21 and the outer wall of the drain pipe 22 are prevented from being attached together to influence the filling of the gap between the sleeve 21 and the drain pipe 22.

In the construction process of filling the gap around the drain assembly 20, the bracket 23 is arranged between the sleeve 21 and the drain pipe 22 to separate the sleeve 21 and the drain pipe 22, so that the inner wall of the sleeve 21 and the outer wall of the drain pipe 22 are prevented from being attached together to influence the filling of the gap between the sleeve 21 and the drain pipe 22. In the specific implementation steps, a first plugging layer is formed by plugging a gap between the end of the sleeve 21 and the foundation bed layer 210, a second plugging layer is formed by plugging a gap between the end of the drain pipe 22 and the end of the sleeve 21, a grouting hole 400 and an exhaust hole 500 are formed in the first plugging layer or the second plugging layer, slurry is injected from the grouting hole 400 by using a high-pressure grouting pump, a slurry leaking hole is formed in the side wall of the sleeve 21, the slurry enters the gap between the drain pipe 22 and the sleeve 21 and the gap between the sleeve 21 and the foundation bed layer 210 along the slurry leaking hole, gas or liquid in the gap around the drainage assembly 20 is exhausted from the exhaust hole 500, the slurry gradually fills the gap around the drainage assembly 20 from the slurry leaking hole until the slurry completely fills the gap around the drainage assembly 20, and the grouting is stopped. Of course, after grouting, the grouting holes 400 and the exhaust holes 500 need to be plugged, so that on one hand, the grouting holes 400 and the exhaust holes 500 are prevented from becoming a circulation channel of underground water, and on the other hand, liquid from the outside is prevented from entering the roadbed through the grouting holes 400 and the exhaust holes 500. It can be understood that if there is a situation that the grouting amount is not full in the gap around the drainage assembly 20, a plurality of grouting holes 400 and exhaust holes 500 may be provided, and the grouting holes 400 or the exhaust holes 500 may all be provided on the first blocking layer, the second blocking layer, or both the first blocking layer and the second blocking layer.

In an embodiment, referring to fig. 2, in order to further facilitate grouting, a grouting hole 400 may be formed in the foundation bed surface layer 220 or the ballastless track 100, one end of the grouting hole 400 extends into a gap between the casing 21 and the foundation bed bottom layer 210, a high-pressure grouting pump is used for grouting from the other end of the grouting hole 400, the slurry gradually fills the gap between the casing 21 and the foundation bed bottom layer 210, and then the slurry gradually fills the gap between the casing 21 and the drain pipe 22 through the slurry leaking hole.

In one embodiment of the present application, referring to fig. 3, the bracket 23 is disposed between the sleeve 21 and the drainage pipe 22 at an interval. The spaced bracket 23 can better separate the sleeve 21 from the drain pipe 22, and also can reduce the volume of the bracket 23, and can be conveniently arranged between the sleeve 21 and the drain pipe 22. Specifically, the distance between two adjacent brackets 23 is 15 cm-30 cm. This design, with fewer brackets 23, ensures a better separation of the sleeve 21 from the drain pipe 22, saving costs.

In order to further facilitate the construction of ballastless tracks with relatively narrow space, in an embodiment of the present application, please refer to fig. 3, the length of the casing 21 is 40cm to 60 cm. For example, 40cm, 45cm, 50cm, 55cm, 60 cm. It will be appreciated that a plurality of sleeves 21 may be used in combination to form a conduit having a length that meets the drainage distance requirements. Illustratively, the plurality of sleeves 21 may be connected back and forth to form a long drain line, and the connection between the plurality of sleeves 21 may be welded or screwed or connected by a joint. In a particular embodiment, two adjacent sleeves 21 are welded. The design is convenient for sealing the joint between the two sleeves 21 and preventing water from seeping out at the joint of the two sleeves 21. In another embodiment, two adjacent sleeves 21 are threaded. Not only the positioning connection between the two sleeves 21 is facilitated, but also the sealing performance between the two sleeves 21 is facilitated to be improved. In particular, it is possible that one end of the sleeve 21 has an external thread and the opposite end has a matching internal thread. It is also possible that the sleeve 21 comprises a first sleeve (not shown) having an internal thread at both ends and a second sleeve having an external thread at both ends adapted to the internal thread of the first sleeve, the first sleeve being screwed to the second sleeve. In yet another embodiment, two adjacent sleeves 21 are connected by a joint. This design facilitates further improvement of the sealing between the two sleeves 21. In particular, the joint may be a female or male joint or a band.

In an embodiment of the present application, referring to fig. 2, the drainage preventing structure includes a gutter 40 disposed in the inter-line region, and the gutter 40 communicates two adjacent water collecting wells 10. The gutters 40 communicate with two adjacent water collection wells 10, so that liquid in the inter-line area can enter the water collection wells 10 through the gutters 40, and then can be discharged out of the ballastless track 100 through the drainage assemblies 20.

In one embodiment of the present application, referring to fig. 2, the ditch 40 is an open ditch, i.e. the ditch 40 is disposed above the surface of the foundation bed in the inter-line region, and the ditch 40 communicates two adjacent water collecting wells 10. The gutters 40 are used to drain the surface liquid in the line area to the water collection well 10. When the ditch 40 is an open ditch, in order to quickly set up the ditch in the embodiment of the present application in the inter-line region, the ditch in the embodiment of the present application may be set in the construction process of setting the first sealing layer 30, specifically, when the first sealing layer 30 is formed, a ditch template may be placed, the ditch template may adopt a pipe with a set radius, the pipe may be fixed by a fastening connector, then concrete is poured on the foundation bed surface layer 220 avoiding the water collecting well 10 in the inter-line region to form the first sealing layer 30, and after the construction of the first sealing layer 30 is completed, the ditch template is removed, and then the ditch 40 is formed. The gutters 40 communicate with two adjacent water collection wells 10, so that liquid in the inter-line area can enter the water collection wells 10 through the gutters 40, and then can be discharged out of the ballastless track 100 through the drainage assemblies 20.

In another embodiment of the present application, the gully 40 is a blind gully, i.e. the gully 40 is embedded in the bedding surface of the interline area, and the gully 40 communicates with two adjacent water collection wells 10. The drain 40 is an underdrain for draining fluid in the bedding surface in the interline region to the sump 10.

In order to facilitate the liquid in the ditch 40 to enter the water collecting well 10, in an embodiment of the present application, referring to fig. 2, the ditch 40 is a longitudinal slope of 0.1% to 0.5%.

In an embodiment of the present application, referring to fig. 2, the waterproof and drainage structure includes a second sealing layer 50 disposed on a shoulder of the ballastless track 100, and a height of the second sealing layer 50 is lower than a height of the supporting layer 110. With the structure, liquid collected on the road shoulder of the ballastless track 100 can be conveniently discharged out of the ballastless track 100 from the upper surface of the second sealing layer 50.

If set up second seal 50 on current ballastless track curb, then need with the shoulder graded gravel layer of current ballastless track and the curb seal that is located shoulder graded gravel layer top chisel, can adopt electronic pick or the supporting pneumatic pick of air compressor machine to chisel away shoulder graded gravel layer and curb seal, can adopt the cutting machine to chive again with thick part piecemeal to the thick part of curb seal, transport the output outside through flatbed or small handcart. Of course, if the second sealing layer 50 is disposed on the newly constructed ballastless track shoulder, the second sealing layer 50 may be disposed directly on the shoulder without this step. The second closing layer 50 may also be formed using fiber concrete casting.

In order to further facilitate the liquid collected on the shoulder of the ballastless track 100 to be discharged from the ballastless track 100 from the upper surface of the second sealing layer 50, in an embodiment of the application, referring to fig. 2, the second sealing layer 50 is a 3% to 6% cross slope.

In order to facilitate the liquid on the first sealing layer 30 to rapidly enter the water collecting well 10 and/or the ditch 40, in one embodiment of the present application, referring to fig. 2, one end of the first sealing layer 30 close to the supporting layer 110 is higher than one end of the first sealing layer 30 close to the ditch 40. Further, the slope between the end of the first sealing layer 30 adjacent to the support layer 110 and the end of the first sealing layer 30 adjacent to the gutter 40 is 3% to 6%.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and all the changes or substitutions should be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. The utility model provides a drainage structures of ballastless track road bed which characterized in that, drainage structures includes:

2. The water repellant structure of claim 1, wherein the drain assembly includes a sleeve and a drain tube nested within the sleeve.

3. The waterproof and drainage structure as claimed in claim 2, wherein the side wall of the sleeve is provided with a slurry leakage hole.

4. The drain prevention structure of claim 2 wherein the drain assembly comprises a bracket disposed between the sleeve and the drain pipe, the bracket for spacing the sleeve from the drain pipe.

5. The drain prevention structure of claim 4 wherein the bracket is spaced between the sleeve and the drain pipe;

and/or the length of the sleeve is 40 cm-60 cm.

6. The structure of any one of claims 1 to 5, wherein the structure includes gutters disposed in the inter-line region, the gutters communicating with two adjacent water collection wells.

7. The waterproof and drainage structure of claim 6, wherein the gutter is a longitudinal slope of 0.1% to 0.5%.

8. The waterproof and drainage structure as claimed in any one of claims 1 to 5, wherein the waterproof and drainage structure comprises a second sealing layer arranged on the ballastless track shoulder, and the height of the second sealing layer is lower than that of the supporting layer.

9. The waterproof and drainage structure of claim 8, wherein the second sealing layer has a cross slope of 3% to 6%.

10. The drain-resistant structure of claim 6 wherein the end of the first closure layer adjacent the support layer is higher than the end of the first closure layer adjacent the gutter.