A V-shaped gully high fill temporary drainage system and construction method thereof

Abstract

The invention discloses a V-shaped gully high fill temporary drainage system and a construction method thereof. The temporary drainage system comprises a V-shaped natural gully and a fill roadbed built in the V-shaped natural gully. A gravel blind ditch is arranged at the bottom of the fill roadbed. The fill roadbed is filled in layers. A trapezoidal drainage ditch is arranged on one side of the layered fill roadbed. A waterproof geomembrane is laid on the surface of the trapezoidal drainage ditch. The invention is suitable for temporary drainage during the filling process of the fill roadbed in the V-shaped natural gully. The drainage ditch is easy to set up and the construction is simple. In particular, a large amount of water can be prevented from infiltrating the fill roadbed during the construction process. The invention has low construction cost and is easy to promote.

Description

Technical Field

[0001] The invention relates to a V-shaped gully high-fill temporary drainage system and a construction method thereof, belonging to the technical field of V-shaped gully high-fill temporary drainage. Background Art

[0002] The landform types in mountainous areas are mostly erosion structures and river valley terraces. Affected by faults, folds and other structures, the terrain is undulating, with obvious peaks and valleys and gullies. The terrain, hydrology and climate conditions are very complex. The surface is eroded and scoured to varying degrees by water flow, forming many V-shaped natural gullies. As high-grade highways are built in mountainous areas, the route layout is restricted by terrain and linear indicators, and it is inevitable that many V-shaped gully high-fill sections will be produced.

[0003] V-shaped natural gullies are the main drainage corridors for surface water or some groundwater in mountainous areas. There are long-term water flows or seasonal rain-source water flows. If the rainfall is concentrated during the flood season, the water flow in the gully is large, and if the rainfall is small in winter, the water flow in the gully is small. Therefore, the high fill roadbed set up for highway routes across V-shaped natural gullies must avoid the following problems:

[0004] (1) During the filling process, the water content of the fill material plays a very important role in improving the compaction degree. The water flow in the gully penetrates into the fill roadbed, and the water content of the fill material is much higher than the optimal water content. If the water content is too high or too low, the compaction effect will be difficult to meet the requirements, resulting in large settlement and deformation of the embankment after construction, which seriously affects driving safety and comfort;

[0005] (2) During the flood season, rainfall is concentrated and the intensity of rainfall is high. Water in the V-shaped natural gullies gathers quickly, and the fill roadbed needs to be compacted layer by layer. Due to the limitations of the fill source, fill transportation and filling rate, the construction period is long. During the filling process, it is easy for a barrier lake to form at the rear edge of the fill. A large amount of water penetrates deep into the roadbed, and the seepage easily hollows out the fill base. At the same time, the shear strength and deformation modulus of the roadbed fill are reduced, causing the fill roadbed to slip and become unstable.

[0006] At present, the common drainage measures for high fill roadbeds across V-shaped natural gullies include ditch bottom seepage blind ditch and buried culverts at the bottom of the fill. However, the drainage capacity of the ditch bottom seepage blind ditch is limited and it is not suitable for areas with large water volume. The buried culverts at the bottom of the fill are more used in sections where the gully has water all year round and the roadbed is shorter. In high fill sections, there are problems such as culvert crushing, later culvert treatment and economic costs, and they are rarely used in actual construction.

[0007] In view of this, in order to solve the temporary drainage problem of high fill roadbed in V-shaped natural gullies and reduce the difficulty of high fill roadbed construction, it is urgent to invent a V-shaped gully high fill temporary drainage system and its construction method to ensure the construction efficiency, safety and stability of the high fill roadbed. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a V-shaped gully high fill temporary drainage system and a construction method thereof, which is suitable for temporary drainage during the filling roadbed filling process in a V-shaped natural gully. The drainage ditch is easy to set up and the construction is simple, especially preventing a large amount of water from infiltrating the fill roadbed during the construction process. The system also has a low construction cost and is easy to promote, thus overcoming the shortcomings of the prior art.

[0009] The technical solution of the present invention is: a V-shaped gully high fill temporary drainage system and a construction method thereof, the temporary drainage system comprises a V-shaped natural gully and a fill roadbed filled in the V-shaped natural gully, a gravel blind ditch is arranged at the bottom of the fill roadbed, the fill roadbed is filled in layers, a trapezoidal drainage ditch is arranged on one side of the layered fill roadbed, and a waterproof geomembrane is laid on the surface of the trapezoidal drainage ditch.

[0010] The above-mentioned gravel blind ditch is composed of a blind ditch top plate, a water-filtration geonet, permeable gravel and a blind ditch base; the permeable gravel is filled between the blind ditch top plate and the blind ditch base, and a water-filtration geonet is provided on both sides of the permeable gravel.

[0011] The above-mentioned permeable crushed stone is built by masonry using a combination of one or more of crushed stone, piece stone or permeable block stone.

[0012] The above-mentioned trapezoidal drainage ditch is located at the top of each layer of the fill roadbed, and the trapezoidal drainage ditch is staggered and moved to one side of the fill roadbed layer by layer.

[0013] The size of the trapezoidal drain ditch is determined by the following steps:

[0014] I. Determine the natural gully storm flood flow Q0 and the initial trapezoidal drainage ditch bottom width b, height h, and slope ratio 1:m, where m is 1 to 2;

[0015] II. Determine the minimum cross-sectional area A of the trapezoidal drainage ditch according to the following formula and formula

[0016]

[0017] In the formula, v is the average flow velocity, R is the hydraulic radius, n is the roughness coefficient, and i is the hydraulic slope;

[0018] III. Repeated iteration until Q i ≥Q0, determine the final bottom width b, height h, and slope ratio m.

[0019] The above-mentioned waterproof geomembrane is laid in sections on the surface of the trapezoidal drainage ditch, with the laying width exceeding the top of the trapezoidal drainage ditch, and each section is laid in an overlapping manner.

[0020] The construction method of the V-shaped gully high fill temporary drainage system has the following steps: a. build a gravel blind ditch at the bottom of the "V"-shaped natural gully and fill roadbed; b. fill the fill roadbed layer A and calculate the size to fill the trapezoidal drainage ditch, and then lay a waterproof geomembrane. After completion, the water flow is introduced into the trapezoidal drainage ditch; c. fill the next layer B fill, fill the trapezoidal drainage ditch on the other side of the trapezoidal drainage ditch of the A layer, lay a waterproof geomembrane, and guide the water flow into the trapezoidal drainage ditch; After introducing the trapezoidal drainage ditch of this layer, cut off the trapezoidal drainage ditch of layer A and take out the waterproof geomembrane inside; d. Fill the next layer, layer C, and build a trapezoidal drainage ditch on the other side of the trapezoidal drainage ditch of layer B, lay the waterproof geomembrane taken out of layer A, introduce the water flow into the trapezoidal drainage ditch of this layer, cut off the trapezoidal drainage ditch of layer B and take out the waterproof geomembrane inside; f. Repeat steps c and d until the top of the Nth layer of fill roadbed, and then build a permanent surface drainage ditch.

[0021] Compared with the prior art, the V-shaped gully high fill temporary drainage system and its construction method of the present invention have the following beneficial effects:

[0022] (1) Before constructing the high fill roadbed, a gravel blind ditch is first constructed to meet the basic surface seepage requirements. Then a trapezoidal drainage ditch is constructed and a waterproof geomembrane is laid to divert the runoff from the rear gully into a temporary drainage ditch. The construction is simple and quick.

[0023] (2) Through the two measures of seepage through the gravel blind ditch and discharge of runoff in the gully through the trapezoidal drainage ditch, a complete drainage system is formed. Compared with the conventional high fill drainage method, it effectively avoids the problem of deformation and instability caused by water immersion during the construction of the fill roadbed.

[0024] (3) As the fill roadbed is filled, the trapezoidal drainage ditches on both sides of the fill are continuously moved and raised to avoid the formation of a barrier lake at the rear edge of the fill. When filling to the top of each layer, a trapezoidal drainage ditch is directly reserved without excavation, which does not affect the filling and tamping of the next layer of fill, thereby improving construction safety and greatly saving construction time. After completion, a waterproof geomembrane is directly laid, and the trapezoidal drainage ditch is moved according to the progress of the construction. The waterproof geomembrane of the previous layer can be recycled for reuse, reducing the amount of temporary drainage measures and reducing construction costs.

[0025] (4) The present application can be applied to embankment sections in gully terrain with large amounts of water. It has a wider scope of application and more thorough drainage, thus improving the filling quality and safety and stability of high embankment roadbeds. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings, in which:

[0027] Figure 1 It is a schematic diagram of a V-shaped gully high fill temporary drainage system and a construction method of the present invention.

[0028] Figure 2 It is a schematic diagram of the cross-sectional structure of the gravel blind ditch of the present invention.

[0029] Figure 3 It is a schematic cross-sectional view of a trapezoidal drainage ditch according to the present invention.

[0030] Figure 4 It is a schematic diagram of the plane laying of the trapezoidal drainage ditch of the present invention.

[0031] Figure 5 Schematic diagram of a trapezoidal drainage ditch according to an embodiment of the present invention.

[0032] Figure 6 It is a schematic diagram of the drainage system construction process of an embodiment of the present invention.

[0033] Among them, there are V-shaped natural gully 1; fill roadbed 2; gravel blind ditch 3; blind ditch top plate 3-1; water filtration geonet 3-2; permeable gravel 3-3; blind ditch base 3-4; trapezoidal drainage ditch 4; waterproof geomembrane 5. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the preferred embodiments are only for illustrating the present invention, rather than for limiting the protection scope of the present invention.

[0035] Example 1. Figure 1 As shown, a V-shaped gully high fill temporary drainage system comprises a V-shaped natural gully 1 and an embankment roadbed 2 built in the V-shaped natural gully 1, a gravel blind ditch 3 is arranged at the bottom of the embankment roadbed 2, the embankment roadbed 2 is filled in layers, a trapezoidal drainage ditch 4 is arranged on one side of the layered embankment roadbed 2, and a waterproof geomembrane 5 is laid on the surface of the trapezoidal drainage ditch 4.

[0036] Figure 2 As shown, the gravel blind ditch 3 is composed of a blind ditch top plate 3-1, a water-filtration geonet 3-2, permeable gravel 3-3 and a blind ditch base 3-4; the permeable gravel 3-3 is filled between the blind ditch top plate 3-1 and the blind ditch base 3-4, and a water-filtration geonet 3-2 is provided on both sides of the permeable gravel 3-3.

[0037] The permeable crushed stone 3-3 is built by masonry using a combination of one or more of crushed stone, block stone or permeable block stone.

[0038] The trapezoidal drainage ditch 4 is located at the top of each layer of the fill roadbed 2, and the trapezoidal drainage ditch 4 is staggered layer by layer and moved to one side of the fill roadbed 2. The size of the trapezoidal drainage ditch 4 is determined by the following steps:

[0039] I. Determine the storm flood flow Q0 of the natural gully 1 and the bottom width b, height h, and slope ratio 1:m of the initial trapezoidal drainage ditch 4, where m is generally 1 to 2;

[0040] II. Determine the minimum cross-sectional area A of the trapezoidal drainage ditch 4 according to the following formulas 1 and 2

[0041]

[0042] In the formula, v is the average flow velocity, R is the hydraulic radius, n is the roughness coefficient, and i is the hydraulic slope;

[0043] III. Repeated iteration until Q i ≥Q0, determine the final bottom width b, height h, and slope ratio 1:m.

[0044] The waterproof geomembrane 5 is laid in sections on the surface of the trapezoidal drainage ditch 4, with the laying width exceeding the top of the trapezoidal drainage ditch, and each section is laid in an overlapping manner.

[0045] The construction method of the V-shaped gully high fill temporary drainage system has the following steps:

[0046] a. Build a gravel blind ditch 3 at the bottom of the "V"-shaped natural gully 1 and the fill roadbed 2;

[0047] b. Fill the A layer of fill roadbed 2 and calculate the size of the trapezoidal drainage ditch 4, and then lay the waterproof geomembrane 5. After completion, the water flow is introduced into the trapezoidal drainage ditch 4;

[0048] c. Fill the next layer B, fill a trapezoidal drainage ditch 4 on the other side of the trapezoidal drainage ditch 4 of the A layer, lay a waterproof geomembrane 5, and after introducing the water flow into the trapezoidal drainage ditch 4 of this layer, cut off the trapezoidal drainage ditch 4 of the A layer, take out the waterproof geomembrane 5 therein and fill it;

[0049] d. Fill the next layer, the Cth layer, fill the trapezoidal drainage ditch 4 on the other side of the trapezoidal drainage ditch 4 of the Bth layer, lay the waterproof geomembrane 5 taken out of the Ath layer, introduce the water flow into the trapezoidal drainage ditch 4 of this layer, cut off the trapezoidal drainage ditch 4 of the Bth layer, take out the waterproof geomembrane 5 therein and fill it;

[0050] f. Repeat steps c and d until the top of the Nth layer of fill roadbed 2, and then build a permanent surface drainage ditch.

[0051] Specifically, the construction process of the V-shaped gully high fill temporary drainage system is combined with Figure 5 , Figure 6 , as follows:

[0052] In this example, the height of the high fill is 20m, and the storm flood flow in the natural gully is determined to be Q0 = 9.9m 3 / s; According to step I, the bottom width of the trapezoidal drainage ditch is preliminarily determined to be b = 2m, the height h = 1.5m, and the slope ratio m = 1, and the hydraulic radius R = 1.05m, the roughness coefficient n = 0.015, and the hydraulic slope i = 0.02 are calculated; according to formula (1) in steps II and III, v = 9.74m / s, and formula (2) gives Q = 10.2m 3 / s>Q0=9.9m 3 / s, the determined trapezoidal drainage ditch size meets the discharge capacity requirements, then the trapezoidal drainage ditch size bottom width b = 2m, height h = 1.5m, slope ratio m = 1, such as Figure 4 shown.

[0053] After the size of the trapezoidal drainage ditch is determined, the length of the waterproof geomembrane segment is determined to be 15m, the laying width exceeds the top of the trapezoidal drainage ditch by 0.5m, and the overlap length of each segment is 0.5m. The required waterproof geomembrane area for each segment is 108m 2 .

[0054] The high fill roadbed is 20m high and is compacted layer by layer using strong tamping. The layer thickness is 5m and is divided into 4 layers. The temporary drainage system of the high fill is constructed using the method in this example. The construction process is as follows:

[0055] According to step a, a gravel blind ditch is built at the bottom of the fill roadbed. According to step b, a trapezoidal drainage ditch of a determined size is built on the left side of the first layer, and then the water flow in the gully is introduced into the ditch to fill and compact the first layer of fill; then according to step c, the second layer of fill roadbed is filled, and a trapezoidal drainage ditch is reserved on the other side, and a waterproof geomembrane is laid. After completion, the first layer of trapezoidal drainage ditch is cut off and the waterproof geomembrane is taken out, and the water flow is introduced into the ditch of the current layer; then according to step d, the third layer of fill roadbed is filled, and the first layer of waterproof geomembrane is reused. After completion, the second layer of ditch is cut off and the waterproof geomembrane is taken out, and the water flow is introduced into the ditch of the current layer; repeat step d to fill the fourth layer of fill roadbed, and the waterproof geomembrane in the second layer is reused. After completion, the third layer of ditch is cut off and the waterproof geomembrane is taken out, and the water flow is introduced into the ditch of the current layer. After the permanent drainage ditch is built, the waterproof geomembrane of the current layer is taken out, and the high fill roadbed is filled.

[0056] It can be seen that the method of the present invention can determine the drainage ditch with corresponding discharge capacity according to different natural gully flood flows, and the position of the temporary drainage ditch can be changed accordingly according to the construction progress. Compared with the conventional high fill drainage method, the present invention can be applied to gully terrain fill roadbed sections with large water volume. It has a wider range of applications and more thorough drainage, which improves the filling quality and safety and stability of the fill roadbed.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A V-shaped gully high fill temporary drainage system, comprising a V-shaped natural gully (1) and a fill roadbed (2) built in the V-shaped natural gully (1), characterized in that: The fill roadbed (2) is filled in layers, a gravel blind ditch (3) is provided at the bottom of the fill roadbed (2), a trapezoidal drainage ditch (4) is provided on one side of the layered fill roadbed (2), and a waterproof geomembrane (5) is laid on the surface of the trapezoidal drainage ditch (4); The trapezoidal drainage ditch (4) is located at the top of each layer of the fill roadbed (2), and the trapezoidal drainage ditch (4) is staggered and moved to one side of the fill roadbed (2) layer by layer; The size of the trapezoidal drainage ditch (4) is determined by the following steps: I. Determine the storm flood flow Q0 of the natural gully (1) and the bottom width b, height h, and slope ratio 1:m of the initial trapezoidal drainage ditch (4), where m is 1 to 2; II. Determine the minimum cross-sectional area A of the trapezoidal drainage ditch (4) according to the following formulas (1) and (2): In the formula, v is the average flow velocity, R is the hydraulic radius, n is the roughness coefficient, and i is the hydraulic slope; III. Repeated iteration until Q i ≥Q0, determine the final bottom width b, height h, and slope ratio 1:m; The construction method and steps of the V-shaped gully high fill temporary drainage system are as follows: a. Constructing a gravel blind ditch (3) at the bottom of the V-shaped natural gully (1) and the fill roadbed (2); b. Fill the embankment (2) layer A and calculate the size of the trapezoidal drainage ditch (4), and then lay a waterproof geomembrane (5). After completion, the water flow is introduced into the trapezoidal drainage ditch (4); c. Fill the next layer B, fill a trapezoidal drainage ditch (4) on the other side of the trapezoidal drainage ditch (4) of the A layer, lay a waterproof geomembrane (5), and after introducing water flow into the trapezoidal drainage ditch (4) of this layer, cut off the trapezoidal drainage ditch (4) of the A layer and remove the waterproof geomembrane (5) therein; d. Fill the next layer of fill, the C layer, fill a trapezoidal drainage ditch (4) on the other side of the trapezoidal drainage ditch (4) of the B layer, lay the waterproof geomembrane (5) taken out of the A layer, introduce the water flow into the trapezoidal drainage ditch (4) of this layer, cut off the trapezoidal drainage ditch (4) of the B layer and take out the waterproof geomembrane (5) therein; f. Repeat steps c and d until the top of the Nth layer of the fill roadbed (2), and then build a permanent surface drainage ditch.

2. The V-shaped gully high fill temporary drainage system according to claim 1 is characterized by: The gravel blind ditch (3) is composed of a blind ditch top plate (3-1), a water-filtration geonet (3-2), permeable gravel (3-3) and a blind ditch base (3-4); the permeable gravel (3-3) is filled between the blind ditch top plate (3-1) and the blind ditch base (3-4), and a water-filtration geonet (3-2) is provided on both sides of the permeable gravel (3-3).

3. The V-shaped gully high fill temporary drainage system according to claim 1 is characterized by: The waterproof geomembrane (5) is laid in sections on the surface of the trapezoidal drainage ditch (4), with the laying width exceeding the top of the trapezoidal drainage ditch, and each section is laid in an overlapping manner.

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