A kind of anti-seepage flexible step spillway and its construction method

Abstract

The invention discloses an anti-seepage flexible step spillway and a construction method thereof, and relates to the technical field of water conservancy. The invention adjusts and designs the original vertical slope built by geobags into a combined structure of a spillway inclined slope and a spillway slope step, which can better guide the flow of water and more efficiently spill the water; the backfill soil in the CDASS geobag, the inclined slope of the spillway and the formed backfill soil of the spillway slope step are all cemented soil mixed with lime, cement and soil, which can better ensure the anti-scouring and anti-erosion properties of the soil spillway and the stability of the slope and the chute; the exposed part of the entire spillway is treated with anti-seepage, which effectively prevents the erosion, penetration and scouring damage of the dam body by the water flow, and ensures the integrity and reliability of the dam body and the spillway; the original smooth U-shaped nails are replaced with T-shaped nails with a threaded structure, which increases the anchoring effect, and the anti-seepage flexible step spillway has high construction efficiency and uses less materials.

Description

Technical Field

[0001] The invention relates to the technical field of water conservancy, and in particular to an anti-seepage flexible step spillway and a construction method thereof. Background Art

[0002] The traditional silt dam spillway is built with non-impermeable geobags, and the spillway slope is lined with geobags. Due to the huge volume of the original geobags in the actual construction process, their own weight is doubled, and the lower soil geobags bear a huge weight. When the spillway is discharged, water penetrates into it, causing the overall structure of the spillway to deform and damage. The soil filled inside the geobag is original soil. If the soil is sandy soil, its internal cohesion is zero, and it is impossible to meet the strength requirements of the spillway through compaction. The anchor nails of the traditional spillway are smooth U-shaped nails, and the anchoring effect is relatively poor. At the same time, the traditional spillway is a non-impermeable spillway. When the spillway is discharged, as the water level rises, the erosion and permeability of the water flow continue to increase, which in turn damages the overall structure of the spillway. In addition, the construction process of this type of spillway is relatively complicated, the construction difficulty is relatively large, and the construction period is long. Summary of the invention

[0003] The present invention provides an anti-seepage flexible step spillway and a construction method thereof, which can alleviate the above-mentioned problems.

[0004] In order to alleviate the above-mentioned problems, the technical solution adopted by the present invention is as follows:

[0005] In a first aspect, the present invention provides an anti-seepage flexible step spillway, comprising a dam body, wherein the dam body is provided with a spillway chute, wherein a plurality of spillway steps are provided in the spillway chute, wherein a plurality of CDASS geobags are laid on the spillway steps, wherein the CDASS geobags are fixed by anchor nails,

[0006] The left and right side slope structures of the spillway chute are the same, both including a spillway inclined side slope and a spillway side slope step, the spillway side slope step on the same side is connected to the backwater slope surface of the dam body through the spillway inclined side slope on that side, and the spillway inclined side slopes on both sides form an inverted figure eight structure;

[0007] The exposed part of the entire spillway is fixed with a flexible anti-seepage geocomposite layer by anchor nails, and the anchor nails are T-shaped nails with threads processed on the anchoring part;

[0008] The CDASS geobag is filled with cemented soil mixed with lime, cement and soil, and the spillway slope and spillway slope steps are backfilled and formed by cemented soil.

[0009] The technical effects of this technical solution are: the original vertical slope built with geobags is adjusted and designed to be a combination structure of the inclined slope of the spillway and the spillway slope steps, which can better guide the flow of water and more efficiently overflow the water; the backfill soil in the CDASS geobag, the inclined slope of the spillway and the formed backfill soil of the spillway slope steps are all cemented soil mixed with lime, cement and earth, which can better ensure the anti-scouring and anti-erosion properties of the earth spillway and the stability of the slope and the chute; the exposed part of the entire spillway has been treated with anti-seepage, which effectively prevents the erosion, penetration and scouring damage of the dam body by water flow, and ensures the integrity and reliability of the dam body and the spillway; the anchoring method and materials have been readjusted and designed, and the original smooth U-shaped nails have been replaced with T-shaped nails with a threaded structure, which increases the anchoring effect.

[0010] In a second aspect, the present invention provides a construction method for an anti-seepage flexible step spillway, comprising the following steps:

[0011] S1. Dig a spillway chute along the upper plane of the dam body, the backwater slope surface, and the backwater lower plane of the dam body. The spillway chute is a through chute;

[0012] S2. Construct spillway steps on the inclined surface of the spillway chute;

[0013] S3, preparing cemented soil;

[0014] S4, backfilling the left and right backfill areas in the spillway chute with cemented soil to reinforce the left and right side walls of the spillway chute;

[0015] S5. Build spillway slopes and spillway slope steps on the backfilled parts on the left and right sides of the spillway chute;

[0016] S6. Lay CDASS geobags on the spillway steps, fill the CDASS geobags with cementing soil, anchor the CDASS geobags with T-nails, sew the mouths of the CDASS geobags, and apply cyanide gel on the surface of the CDASS geobags;

[0017] S7. When the cyanide applied on the surface of the CDASS geobag changes from liquid to viscous or has a drawing-like feature, a flexible anti-seepage geocomposite layer is laid on the exposed part of the current spillway and anchored by T-type nails;

[0018] S8. Apply cyanide coagulation three times on the surface of the laid flexible anti-seepage geocomposite layer, and the interval between applications is 12-24 hours;

[0019] S9. Dig boundary fixing soil trenches on the back slopes on both sides of the current spillway, and fix the left and right edges of the flexible anti-seepage geocomposite layer in the boundary fixing soil trenches on both sides through backfill soil and T-shaped nails to complete the construction of the spillway.

[0020] The technical effect of this technical solution is: the amount of materials used is one-third of the amount of materials used in traditional spillways, and the construction process is simpler and faster, which greatly shortens the construction period to only one-fourth of the original construction period, thereby significantly reducing construction costs.

[0021] Furthermore, in step S2, during the construction of the spillway steps, uneven parts of the spillway steps need to be trimmed.

[0022] The technical effect of this technical solution is to better ensure that the size of the spillway steps after excavation is consistent with the designed size.

[0023] Furthermore, the step S4 specifically includes: constructing left and right side formworks in the spillway chute, and forming a backfill area between the left and right side formworks and the left and right side walls of the spillway chute respectively; backfilling the cemented soil into the left and right backfill areas in layers; each time a layer of cemented soil is backfilled, a tamping machine is used to compact the cemented soil of the current layer, and the compaction standard is determined according to the compaction test of the cemented soil, and it is necessary to ensure that the compaction density of the cemented soil is not less than 0.98 times the maximum dry density.

[0024] Furthermore, in the step S6, the cemented soil is filled into the CDASS geobag by using a layered compaction method, the bag opening of the CDASS geobag is located at the top of the bag, and the bag opening is sewn by using a handheld sewing machine.

[0025] Furthermore, the width of the CDASS geobag is greater than the width of the spillway step, and there is an overlapping portion between adjacent CDASS geobags.

[0026] The technical effect of this technical solution is that the overlapping supports between adjacent CDASS geobags ensure the laying stability of the CDASS geobags.

[0027] Furthermore, all the overlapping seams of T-shaped nails and the overlapping seams between the flexible anti-seepage geocomposite layer and the CDASS geobag were treated for anti-seepage.

[0028] Furthermore, each time a CDASS geobag is laid, the currently laid CDASS geobag is filled with cemented soil, anchored with T-nails, sewn at the bag mouth, and coated with cyanide. After the current CDASS geobag is coated with cyanide, and the cyanide coated on the surface of the CDASS geobag changes from liquid to viscous or shows a wire-like feature, the next CDASS geobag is laid.

[0029] The technical effect of this technical solution is: high construction efficiency and guaranteed construction quality.

[0030] Furthermore, the anchoring gap around the T-shaped nail is filled with cement mortar.

[0031] The technical effect of this technical solution is to improve the anchoring effect of the T-shaped nail.

[0032] Furthermore, the flexible anti-seepage geocomposite layer is formed by connecting a number of small parts.

[0033] The technical effect of this technical solution is: easy to manufacture and lay.

[0034] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the embodiments of the present invention are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 is a schematic diagram of a first state during the construction of the spillway in the embodiment;

[0037] Figure 2 is a schematic diagram of a second state during the construction of the spillway in the embodiment;

[0038] Figure 3 is a schematic diagram of the third state during the construction of the spillway in the embodiment;

[0039] Figure 4 is a schematic diagram of a fourth state during the construction of the spillway in the embodiment;

[0040] Figure 5 is a schematic diagram of the fifth state during the construction of the spillway in the embodiment;

[0041] Figure 6 is a schematic diagram of the state after the spillway in the embodiment is completed;

[0042] Figure 7 is a schematic diagram of a side cross-sectional state after the spillway in the embodiment is completed;

[0043] In the figure: 1-dam body, 2-backwater slope, 3-spillway chute, 4-spillway steps, 5-backwater underwater plane of dam body, 6-upper plane of dam body, 7-spillway chute backfill part, 8-spillway inclined slope, 9-spillway slope steps, 10-CDASS geobag, 11-T-nail, 12-flexible anti-seepage geocomposite layer, 13-boundary fixed soil trough, 14-geobag overlapping part. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0045] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] Example 1

[0047] Please refer to Figure 1 to Figure 7 The present embodiment provides an anti-seepage flexible step spillway, including a dam body 1, a spillway chute 3 is provided in the dam body 1, a plurality of spillway steps 4 are provided in the spillway chute 3, a plurality of CDASS geobags 10 are laid on the spillway steps 4, the CDASS geobags 10 are fixed by anchor nails, the left and right side slope structures of the spillway chute 3 are the same, both of them include a spillway inclined slope 8 and a spillway side slope step 9, and the spillway side slope step 9 on the same side is connected to the back of the dam body. The water slope surfaces 2 are connected by the oblique side slope 8 of the spillway on this side, and the oblique side slopes 8 of the spillway on both sides form an inverted eight-shaped structure; the exposed part of the entire spillway is fixed with a flexible anti-seepage geocomposite layer 12 by anchor nails, and the anchor nails are T-shaped nails 11 with threads processed on the anchoring part; the CDASS geobag 10 is filled with cemented soil mixed with lime, cement and soil, and the oblique side slope 8 of the spillway and the spillway slope steps 9 are backfilled with cemented soil.

[0048] In this embodiment, the CDASS (Check Dam Soft Spillway) geobag is formed by overlapping, aligning and sewing PET cloth and geotextile; the flexible anti-seepage geocomposite layer 12 is formed by overlapping, aligning and gluing three materials, PET cloth, high-strength geomembrane and geotextile, using a hot melt adhesive method.

[0049] In this embodiment, parameters such as mesh density, weaving weight per unit area, weaving thickness and bonding strength of PET cloth, high-strength geomembrane and geotextile are determined according to influencing factors such as the gradation of the protected soil and permeability requirements.

[0050] In this embodiment, the spillway slope 8 has two inclination directions, the first inclination direction is the front-to-back inclination direction, and the second inclination direction is the left-to-right inclination direction.

[0051] Example 2

[0052] Please refer to Figure 1 to Figure 7 This embodiment provides a construction method of the anti-seepage flexible step spillway described in Embodiment 1, which is as follows:

[0053] S1, digging a spillway chute 3 along the upper plane 6 of the dam body, the backwater slope surface 2, and the backwater lower plane 5 of the dam body, wherein the spillway chute 3 is a through chute;

[0054] S2, build spillway steps 4 on the inclined surface of the spillway chute 3;

[0055] S3, preparing cemented soil;

[0056] S4, backfilling the left and right backfill areas in the spillway chute 3 with cemented soil to reinforce the left and right side walls of the spillway chute 3;

[0057] S5, constructing spillway slope 8 and spillway slope steps 9 on the backfilled parts on the left and right sides of the spillway chute 3;

[0058] S6. Lay CDASS geobags 10 on the spillway step 4, fill the CDASS geobags 10 with cemented soil, anchor the CDASS geobags 10 with T-shaped nails 11, sew the bag openings of the CDASS geobags 10, and apply cyanide coagulation on the surface of the CDASS geobags 10;

[0059] S7. When the cyanide applied on the surface of the CDASS geobag 10 changes from liquid to viscous or has a drawing-like feature, a flexible anti-seepage geocomposite layer 12 is laid on the exposed part of the current spillway and fixed by T-shaped nails 11;

[0060] S8, brush cyanide coagulation 3 times on the surface of the laid flexible anti-seepage geocomposite layer 12, and the brushing interval is 12-24 hours;

[0061] S9. Dig out boundary fixing soil trenches 13 on the back slope surface 2 on the left and right sides of the current spillway, and fix the left and right edges of the flexible anti-seepage geocomposite layer 12 in the boundary fixing soil trenches 13 on both sides by backfilling soil and T-shaped nails to complete the construction of the spillway.

[0062] In this embodiment, the flexible anti-seepage geocomposite layer 12 on the left and the CDASS geobag 10 used are both resistant to high-speed water flow erosion and are not damaged at 5.5m / s; the tensile strength is greater than 95% after freezing for 6 days at -40°C and a light radiation intensity of 550w / ㎡ and continuous illumination for 150 hours, and they have excellent aging resistance and frost resistance; and the material meets the excellent technical indicators of single-filament bidirectional tension greater than 0.19KN / root, double-sided wide-width tensile strength greater than 80KN / m, and CBR bursting strength greater than or equal to 6KN.

[0063] In this embodiment, the mixing ratio of lime, cement and soil in the cementing soil is determined according to the slope stability, soil gradation and spillway slope strength requirements, and is stirred until uniform to ensure the strength of the spillway slope 8 and the CDASS geobag 10 strength requirements.

[0064] In this embodiment, the width of the CDASS geobag 10 is greater than the width of the spillway step 4, and there is an overlap 14 between adjacent CDASS geobags 10. During the construction of the spillway step 4, the uneven part of the spillway step 4 needs to be trimmed, and the size of the spillway step 4 and the CDASS geobag 10 matched therewith, as well as the arrangement density of the T-shaped nails 11 used when fixing the CDASS geobag 10 and the overlapping length of adjacent CDASS geobags 10 are determined according to the flow velocity, flow rate, flow state, force on the step and energy dissipation rate of the water flow in the spillway.

[0065] In this embodiment, when the spillway chute backfill 7 on both sides is used to construct the spillway inclined slope 8 and the spillway slope step 9, the slope ratio of the spillway inclined slope 8 and the width of the spillway slope step 9 are determined based on the spillway slope strength requirements and slope stability requirements.

[0066] In this embodiment, at the overlap of adjacent CDASS geobags 10, a layer of cyanide is first applied for anti-seepage. After the first layer of cyanide is dried, the second layer of cyanide is applied and the CDASS geobag 10 or the flexible anti-seepage geocomposite layer 12 is laid. The second layer of cyanide plays an anti-seepage and bonding function. After the bonding is completed, it is fixed with T-shaped nails 11. After the fixing is completed, glass glue is used to perform secondary anti-seepage treatment on the fine gaps. All the overlapping seams of T-shaped nails 11 and the overlapping seams between the flexible anti-seepage geocomposite layer 12 and the CDASS geobag 10 are treated for anti-seepage. Among them, the interval between each layer of cyanide in the anti-seepage project needs to be determined by factors such as temperature and humidity. Generally, the interval time is 12-24 hours. The cyanide layer that plays a bonding role needs to wait until it becomes viscous or has a wire-like feature before proceeding to the next step.

[0067] In this embodiment, each time a CDASS geobag 10 is laid, the currently laid CDASS geobag 10 is filled with cementitious soil, anchored with T-shaped nails 11, sewn at the bag mouth, and coated with cyanide. After the current CDASS geobag 10 is coated with cyanide and becomes viscous or has a wire-like feature, the next CDASS geobag 10 is laid.

[0068] In this embodiment, the flexible anti-seepage geocomposite layer 12 is formed by sewing and connecting a number of small parts.

[0069] In this embodiment, the anchoring gap around the T-shaped nail 11 is filled with cement mortar, and the T-shaped nail 11 is fixed by a grouting anchoring method. First, the T-shaped nail 11 is driven in to a certain depth and then pulled out, and cement mortar is poured into it, and then all the T-shaped nails 11 are driven in to be fixed.

[0070] In step S8 of this embodiment, the specific operation is: excavating a boundary fixing soil trench 13 in parallel at a certain distance on both sides of the spillway slope, placing the edge of the flexible anti-seepage geocomposite layer 12 in the boundary fixing soil trench 13, and fixing it with T-shaped nails 11, and after fixing, using the layered compaction method to backfill the boundary fixing soil trench 13. The distance between the boundary fixing soil trench 13 and the slope of the spillway and its specific size are determined according to factors such as the discharge flow of the spillway, the scouring and erosion of the water flow on the material, and the like.

[0071] In this embodiment, step S4 specifically includes: constructing left and right side formworks in the spillway chute, and forming a backfill area between the left and right side formworks and the left and right side walls of the spillway chute respectively; backfilling the cemented soil into the left and right backfill areas in layers; each time a layer of cemented soil is backfilled, a tamping machine is used to compact the cemented soil of the current layer, and the compaction standard is determined according to the compaction test of the cemented soil, and it is necessary to ensure that the compaction density of the cemented soil is not less than 0.98 times the maximum dry density.

[0072] In step S6 of the present embodiment, the cemented soil is filled into the CDASS geobag 10 by layered compaction method. The bag opening of the CDASS geobag 10 is located at the top of the bag, and the bag opening is sewn by a handheld sewing machine.

[0073] In this embodiment, the construction process at the inlet of the spillway chute is as follows: first, brush a layer of cyanide on the left and right walls of the inlet; attach the flexible anti-seepage geocomposite layer 12 tightly thereon; after brushing a layer of cyanide on the flexible anti-seepage geocomposite layer 12, glue a rubber strip of a certain width to the surface, brush a layer of cyanide on the other side of the rubber, then glue the steel strips of the same width as the rubber together, and use an electric drill to drill holes at equal intervals on them; place the expansion bolts in the drilled holes and tighten them to prevent water from flowing into the flexible anti-seepage geocomposite layer 12 and damaging the spillway and dam structure. Each time the cyanide is applied, it is necessary to wait until it becomes viscous or has a wire-like feature before proceeding to the next step.

[0074] In this embodiment, after the construction of the spillway is completed, it is necessary to check whether the overlaps and joints between each flexible anti-seepage geocomposite layer 12 and the CDASS geobag 10, and between the flexible anti-seepage geocomposite layer 12 and the T-nail 11 are tightly anti-seepage, so as to ensure the integrity and operational reliability of the flexible anti-seepage step spillway.

[0075] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A construction method for an anti-seepage flexible step spillway. The following steps are involved: S1. Dig a spillway chute along the upper plane of the dam body, the backwater slope surface, and the backwater lower plane of the dam body. The spillway chute is a through chute; S2. Construct spillway steps on the inclined surface of the spillway chute; S3, preparing cemented soil; S4, backfilling the left and right backfill areas in the spillway chute with cemented soil to reinforce the left and right side walls of the spillway chute; S5. Build spillway slopes and spillway slope steps on the backfilled parts on the left and right sides of the spillway chute; the spillway slope steps on the same side are connected to the backwater slope of the dam body through the spillway slope on that side, and the spillway slopes on both sides form an inverted figure-eight structure; S6. Lay CDASS geobags on the spillway steps, fill the CDASS geobags with cementing soil, anchor the CDASS geobags with T-nails, sew the mouths of the CDASS geobags, and apply cyanide gel on the surface of the CDASS geobags; S7. When the cyanide applied on the surface of the CDASS geobag changes from liquid to viscous or has a drawing-like feature, a flexible anti-seepage geocomposite layer is laid on the exposed part of the current spillway and anchored by T-type nails; S8. Apply cyanide coagulation three times on the surface of the laid flexible anti-seepage geocomposite layer, and the interval between applications is 12-24 hours; S9. Dig out boundary fixing soil trenches on the backwater slopes on the left and right sides of the current spillway, and fix the left and right edges of the flexible anti-seepage geocomposite layer in the boundary fixing soil trenches on both sides by backfilling soil and T-shaped nails to complete the construction of the spillway; the width of the CDASS geobag is greater than the width of the spillway step, and there is an overlap between adjacent CDASS geobags; all the lap joints of the T-shaped nails and the lap joints between the flexible anti-seepage geocomposite layer and the CDASS geobag are treated with anti-seepage treatment; Each time a CDASS geobag is laid, the currently laid CDASS geobag is filled with cemented soil, anchored with T-nails, sewn at the bag mouth, and coated with cyanide. After the current CDASS geobag is coated with cyanide, and the cyanide coated on the surface of the CDASS geobag changes from liquid to viscous or shows a wire-like feature, the next CDASS geobag is laid.

2. The construction method of the anti-seepage flexible step spillway according to claim 1 is characterized in that: In step S2, during the construction of the spillway steps, it is necessary to trim the uneven parts of the spillway steps.

3. The construction method of the anti-seepage flexible step spillway according to claim 1 is characterized in that: The step S4 specifically includes: constructing left and right side formworks in the spillway chute, and forming a backfill area between the left and right side formworks and the left and right side walls of the spillway chute respectively; backfilling the cemented soil into the left and right backfill areas in layers; and compacting the cemented soil of the current layer with a tamping machine for each backfilled layer of cemented soil, and the compaction standard is determined according to the compaction test of the cemented soil, and it is necessary to ensure that the compaction density of the cemented soil is not less than 0.98 times the maximum dry density.

4. The construction method of the anti-seepage flexible step spillway according to claim 1 is characterized in that: In the step S6, the cemented soil is filled into the CDASS geobag by using the layered compaction method. The bag opening of the CDASS geobag is located at the top of the bag, and the bag opening is sewn by using a handheld sewing machine.

5. The construction method of the anti-seepage flexible step spillway according to claim 1 is characterized in that: The anchoring gap around the T-shaped nail is filled with cement mortar.

6. The construction method of the anti-seepage flexible step spillway according to claim 1 is characterized in that: The flexible anti-seepage geocomposite layer is formed by connecting a number of small blocks.

7. A floodway using the construction method of the anti-seepage flexible step spillway according to claim 1, comprising a dam body, the dam body is provided with a spillway chute, the spillway chute is provided with a plurality of spillway steps, the spillway steps are paved with a plurality of CDASS geobags, the CDASS geobags are fixed by anchor nails, characterized in that: The left and right side slope structures of the spillway chute are the same, both including a spillway inclined side slope and a spillway side slope step, the spillway side slope step on the same side is connected to the backwater slope surface of the dam body through the spillway inclined side slope on that side, and the spillway inclined side slopes on both sides form an inverted figure eight structure; The exposed part of the entire spillway is fixed with a flexible anti-seepage geocomposite layer by anchor nails, and the anchor nails are T-shaped nails with threads processed on the anchoring part; The CDASS geobag is filled with cemented soil mixed with lime, cement and soil, and the spillway slope and spillway slope steps are backfilled and formed by cemented soil.

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