Ecological embankment structure of water bank slope

Abstract

The invention relates to the technical field of embankments, in particular to a water bank slope ecological embankment structure which comprises a reverse osmosis layer, a reinforcing layer and a stone pile structure, the reverse osmosis layer is obliquely laid on the water facing side of a bank slope, the reinforcing layer is obliquely laid on the reverse osmosis layer, and the stone pile structure is located at the bottom of a water body and pressed on the side, away from the reverse osmosis layer, of the lower end of the reinforcing layer; the reinforcing layer comprises a plant root system anchoring layer, and the upper end of the plant root system anchoring layer extends to the top of the bank slope. Ecological protection can be carried out on the water bank slope, and the stability and anti-scouring performance of the bank slope are improved.

Description

Technical Field

[0001] The invention relates to the technical field of levees, and in particular to an ecological levee structure for a water body bank slope. Background Art

[0002] A dike is a water-retaining structure built along rivers, canals, lakes, coasts, or the edge of flood-carrying areas, flood diversion areas, and reclamation areas. It is also called a levee, and the "prevention" here also means a dike. Dikes can resist flooding, block tides and waves, and protect the safety of residents and industrial and agricultural production within the dike. It is the earliest widely used flood control engineering measure in the world. According to the location of the dike, it can be divided into river (river) dikes, lake dikes, sea dikes, canal dikes, and enclosure dikes.

[0003] Areas near rivers are prone to forming grassland environments due to their abundant water resources throughout the year. Some grasslands are even important water sources for the rivers where they are located, and are vital to the ecology of the rivers. However, due to the soil quality and stratigraphic structure, the slopes of some grasslands near water bodies are steep and unstable, such as the ternary soil body composed of a meadow / peat soil composite layer, a non-cohesive silt layer, and a gravel / gravel sand layer. The above-mentioned slopes are prone to collapse when encountering floods, which not only endangers the flood control safety of infrastructure, but also causes grassland desertification and threatens the ecological stability of wetlands.

[0004] The river bank is usually eroded by floods year by year, the grassland area in the grassland area decreases annually, and the interaction between the erosion and collapse of the shoreline and the degradation of grassland and soil erosion leads to the reduction of wetland patches and the reduction of water conservation function. The reduction of water conservation function of water conservation land will lead to a variety of environmental problems. The water conservation capacity of the upstream is crucial to the regulation of water resources in the entire basin. If the water conservation function of the upstream is reduced, it will lead to insufficient water supply in the downstream area, affecting the production and living water demand in the surrounding areas, and secondly, it will aggravate soil erosion and biodiversity reduction.

[0005] In response to the problem of river bank erosion and damage, there is an urgent need for a levee structure that takes into account both water ecology and flood control safety. Summary of the invention

[0006] The purpose of the present invention is to provide a water body bank slope ecological embankment structure, aiming to improve the problem that the embankment structure in the prior art cannot take into account both water body ecology and flood control safety.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A water body bank slope ecological embankment structure comprises a reverse osmosis layer, a reinforcement layer and a stone pile structure, wherein the reverse osmosis layer is obliquely laid on the water side of the bank slope, the reinforcement layer is obliquely laid on the reverse osmosis layer, and the stone pile structure is located at the bottom of the water body and pressed on the side of the lower end of the reinforcement layer away from the reverse osmosis layer; the reinforcement layer comprises a plant root anchoring layer, and the upper end of the plant root anchoring layer extends to the top of the bank slope.

[0009] Furthermore, the reinforcement layer also includes a geobag layer, which is laid obliquely on the reverse osmosis layer, and the plant root anchoring layer is distributed on the side of the geobag layer away from the reverse osmosis layer, and the plant root anchoring layer extends into the gap between two adjacent geobags in the geobag layer.

[0010] Furthermore, the geobag layer includes a plurality of geobags, the plurality of geobags are stacked, and upper and lower adjacent geobags are staggered.

[0011] Furthermore, the geotextile bag is a woven bag made of polypropylene, the weight of the woven bag is 100g / square meter, the tensile strength in the warp and weft directions are 20kN / m and 17kN / m respectively, and the elongation in the warp and weft directions is 18%.

[0012] Furthermore, the woven bag is filled with sand, and the internal friction angle of the sand inside each geotextile bag is 22° and the gravity is 17 kN / m 3 , saturated density is 21.12kN / m 3 .

[0013] Furthermore, the filling rate of the geobag is 70-90%.

[0014] Furthermore, the plant root anchoring layer includes native aquatic plants.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] In the present invention, by setting up an anti-osmosis layer structure on the water side of the bank slope of the water body, it is beneficial to reduce the seepage erosion inside the bank slope soil body and enhance the anti-slip ability of the bank slope. A reinforcement layer is set on the water side of the anti-osmosis layer. On the one hand, the structural shape of the anti-osmosis layer can be maintained stable through the reinforcement layer, so that the anti-osmosis layer can play its anti-osmosis role. On the other hand, the reinforcement layer can also protect the water side of the anti-osmosis layer to prevent the scouring of the anti-osmosis layer by water flow. On the other hand, the stability of the soil body can be enhanced. The reinforcement layer includes a plant root anchoring layer. Through the anchoring effect of the plant root system, the plant root anchoring layer forms a relatively stable layer. The embankment structure of the present invention forms an ecological embankment structure, which is beneficial to maintaining and protecting biological diversity and can prevent water scouring during flood season and improve the stability of the embankment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0018] Figure 1 It is a schematic diagram of a levee structure and its stability model according to Example 1 of the present invention;

[0019] Figure 2 It is a schematic diagram of a levee structure and its stability model according to Example 2 of the present invention;

[0020] Figure 3 It is a schematic diagram of a levee structure and its stability model according to Example 3 of the present invention;

[0021] Figure 4 It is a comparison chart of the safety factors of Example 1, Example 2, Example 3 and the original slope. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0023] Example 1

[0024] A water body bank slope ecological embankment structure, referring to Figure 1 , including an anti-osmosis layer, a reinforcement layer and a stone pile structure. The anti-osmosis layer is laid obliquely on the water side of the bank slope, and the reinforcement layer is laid obliquely on the anti-osmosis layer. The stone pile structure is located at the bottom of the water body and pressed on the side of the lower end of the reinforcement layer away from the anti-osmosis layer; the reinforcement layer includes a plant root anchoring layer, and the upper end of the plant root anchoring layer extends to the top of the bank slope. Among them, the stone pile structure can be riprap or beech cage stone.

[0025] Among them, the anti-osmosis layer is a sand and gravel structure, and the function of the anti-osmosis layer is to prevent the sand inside the soil from seeping out with the water flow, and to facilitate the discharge of the water pressure in the soil. The plant root anchoring layer includes native water grass plants. Taking the Ruoergai grassland as an example, the soil of the Ruoergai grassland is a ternary soil structure, and its bank slope is a meadow / peat soil root soil composite layer, a non-cohesive soil silt sand layer and an egg / gravel interlayer from top to bottom. The native water grass plants can be at least one of bermudagrass, moss, Chinese flat spike grass and line leaf grass. All four plants are common native slope protection plants. Bermudagrass grows rapidly and has a well-developed root system, but the slope protection effect is weakened in winter. Moss is drought-resistant and cold-resistant, covers tightly, and grows relatively slowly. Chinese flat spike grass is suitable for near-water areas, has an interlaced root system and is resistant to flooding, but has a narrow scope of application. Line leaf grass is suitable for high altitude areas, can form dense meadows, and has a narrow distribution range. Therefore, the plant selection is limited, and the most suitable plant needs to be screened to make it suitable for the Ruoergai ternary structure bank slope.

[0026] By setting up an anti-seepage layer structure on the water side of the water body bank slope, it is beneficial to reduce the seepage erosion inside the bank slope soil and enhance the anti-slip ability of the bank slope. A reinforcement layer is set on the water side of the anti-seepage layer. On the one hand, the reinforcement layer can maintain the stability of the structural shape of the anti-seepage layer, so that the anti-seepage layer can play its anti-seepage role. On the other hand, the reinforcement layer can also protect the water side of the anti-seepage layer to prevent the water flow from scouring the anti-seepage layer. On the other hand, it can also enhance the stability of the soil; and the reinforcement layer includes a plant root anchoring layer. Through the anchoring effect of the plant roots, the plant root anchoring layer forms a relatively stable layered structure. , and the upper end of the plant root anchoring layer extends to the top of the bank slope, so that the plant root anchoring layer and the bank slope form a natural and unified whole, and the lower end of the plant root anchoring layer is pressed down by the stone pile structure, so that the lower end of the plant root anchoring layer is more stably attached to the bank slope, which is beneficial to enhancing the cohesion of the reinforcement layer to the reverse osmosis layer and the soil body, and is beneficial to stabilizing the soil structure. The stone pile structure is also beneficial to preventing deformation of the bank slope and can enhance the anti-scouring ability of the bank slope; the embankment structure of the present invention forms an ecological embankment structure, which is beneficial to maintaining and protecting biological diversity, and can achieve the effect of preventing water scouring during the flood season and improving the stability of the embankment.

[0027] The stability model analysis of the ecological embankment structure in this embodiment adopts the Swedish arc method.

[0028] The calculation formula for the stability safety factor of the ecological embankment form is as follows:

[0029]

[0030] In the formula, in the formula, b i 、b j are the widths of the i-th and j-th soil strips (geobags) of the arc segment and horizontal segment, respectively, in m; l i is the length of the bottom surface of the i-th soil strip in the arc segment, in meters; c i is the effective cohesion of the i-th soil strip in the arc segment, in kN / m 2 ; Δc is the effective cohesion of plant root anchoring, in kN / m2; b i (γ 1i h 1i +γ 2i h 2i +…+γ mi h mi ) is the weight of the i-th soil strip in the arc segment, in kN; α i is the angle between the bottom surface of the i-th soil strip in the arc segment and the horizontal plane, in degrees; is the effective internal friction angle of the i-th soil strip in the arc segment, in degrees; γ w is the density of water, in kN / m 3 ;h w is the water depth during flood season, in m; θ is the slope inclination, in °.

[0031] The parameter selection and calculation of the above ecological embankment form, assuming that the slope ratio is 1:2.5; the expression of the effective cohesion increased by the plant root system is: Where, T r A is the average tensile strength of all roots on the soil shear surface, in MPa; r is the total cross-sectional area of ​​the root system on the shear plane, in m 2 ; A s is the total area of ​​the soil shear surface, in m 2 .

[0032] Example 2

[0033] Based on Example 1, in this example, reference Figure 2 The reinforcement layer also includes a geobag layer, which is laid obliquely on the reverse osmosis layer, and a plant root anchoring layer is distributed on the side of the geobag layer away from the reverse osmosis layer, and the plant root anchoring layer extends into the gap between two adjacent geobags in the geobag layer.

[0034] The geobag layer includes a plurality of geobags, which are stacked and arranged, and the upper and lower adjacent geobags are staggered. The more staggered seams there are, the better the interlayer embedding and biting effect is, achieving the best effect of ensuring the reinforcement of the geobag. A gap is left between two adjacent geobags at the same height, and the taproot anchoring layer extends inside the above gap. The geobag layer can use the interlayer stacking to produce interlayer friction and embedding effect, thereby improving the strength of the soil. The geobag layer can protect the reverse osmosis layer and the slope soil, reduce the scouring effect of floods on the slope soil, and help improve the stability of the slope. In addition, the plant roots in the plant root anchoring layer extend into the gap in the geobag layer, so that the plant roots can anchor and grasp the adjacent geobags, which can further enhance the structural stability of the geobag layer, and the plant root anchoring layer covers the surface of the geobag layer, so that the geobag layer can become a more stable overall structure.

[0035] The geobag is a woven bag made of polypropylene. The weight of the woven bag is 100g / square meter, the tensile strength in the warp and weft directions are 20kN / m and 17kN / m respectively, and the elongation in the warp and weft directions is 18%. The mass per unit area and the tensile strength of the woven bag must meet specific requirements to avoid excessive elongation or rupture during use; the elongation will affect the deformability of the geobag, the sand filling ratio and the contact area between adjacent geobags, thereby affecting the overall stability. Therefore, the material properties of the geobag are limited to ensure the performance and stability of the geobag.

[0036] The woven bag is filled with sand. The internal friction angle of the sand inside each geotextile bag is 22° and the weight is 17kN / m 3 , saturated density is 21.12kN / m 3 The filling materials of geobags are limited to ensure that the filling soil has good particle size distribution, local materials are used, and the project cost is saved.

[0037] The filling rate of geobags is 70-90%. When the filling rate is less than 70%, the stability is greatly affected by the empty bag; when the filling rate is greater than 90%, the geobag is similar to a rock, the deformation capacity is almost lost, and the contact area with the underlying surface is minimized, which is not conducive to the stability of the geobag itself. Therefore, the filling rate of the geobag is limited to ensure the stability of the geobag.

[0038] The forms of ecological embankments include geobags, plants, riprap / gridstone, reverse seepage layer structure and ternary structure slope; the stability model analysis is based on the Swedish arc method, assuming that the sliding surface of the geobag is interlayer horizontal sliding, and the overall sliding surface is composed of the horizontal sliding surface AB at the geobag and the arc sliding surface BC in the soil behind it, which are uniformly divided into strips.

[0039] The calculation formula for the stability safety factor of the ecological embankment in this implementation is as follows:

[0040]

[0041] In the formula, in the formula, b i 、b j are the widths of the i-th and j-th soil strips (geobags) of the arc segment and horizontal segment, respectively, in m; l i is the length of the bottom surface of the i-th soil strip in the arc segment, in meters; c i is the effective cohesion of the i-th soil strip in the arc segment, in kN / m 2 ;c rj is the effective cohesion of the jth geobag in the horizontal section, in kN / m 2 ; Δc is the effective cohesion of plant root anchoring, unit is kN / m 2 ; b i (γ 1i h 1i +γ 2i h 2i +...+γ mi h mi ) is the weight of the i-th soil strip in the arc segment, in kN; W j is the weight of the jth geobag in the horizontal section, in kN; α i is the angle between the bottom surface of the i-th soil strip in the arc segment and the horizontal plane, in degrees; β is the angle between the straight line OB and the normal line of the horizontal sliding surface between the geobag layers, in degrees; is the effective internal friction angle of the i-th soil strip in the arc segment, in degrees; μ is the friction coefficient between geobag layers; γ w is the density of water, in kN / m 3 ;h w is the water depth during flood season, in m; θ is the slope inclination, in °.

[0042] The parameter selection and calculation of the above ecological embankment form, where the horizontal width of the bank slope is set to 1.2m (H≤5) and 1.6m (H>5m), assuming the slope ratio is 1:2.5; according to previous experiments, the calculation formula of the friction coefficient μ between the geobag layers and the vertical pressure P is: μ=-1.93858×10 -5 P 2 +0.00169P+0.67718; effective cohesion of geobag section c r The calculation formula of the bank slope height H1 is: r =82.689H1-6.322; the expression of the effective cohesion of plant roots is: Where, T r A is the average tensile strength of all roots on the soil shear surface, in MPa;r is the total cross-sectional area of ​​the root system on the shear plane, in m 2 ; A s is the total area of ​​the soil shear surface, in m 2 .

[0043] Example 3

[0044] The difference between this embodiment and embodiment 1 is that in this embodiment, referring to Figure 3 , the reinforcement layer includes a geobag layer, and no plant root anchoring layer is used.

[0045] The stability model analysis of the embankment structure in this embodiment is based on the Swedish arc method, assuming that the sliding surface of the geobag is interlayer horizontal sliding, and the overall sliding surface is composed of the horizontal sliding surface AB at the geobag and the arc sliding surface BC in the soil behind it, which are uniformly divided into strips.

[0046] The calculation formula of the stability safety factor of this embankment form is as follows:

[0047]

[0048] Where b i 、b j are the widths of the i-th and j-th soil strips (geobags) of the arc segment and horizontal segment, respectively, in m; l i is the length of the bottom surface of the i-th soil strip in the arc segment, in meters; c i is the effective cohesion of the i-th soil strip in the arc segment, in kN / m 2 ;c rj is the effective cohesion of the jth geobag in the horizontal section, in kN / m 2 ; b i (γ 1i h 1i +γ 2i h 2i +...+γ mi h mi ) is the weight of the i-th soil strip in the arc segment, in kN; W j is the weight of the jth geobag in the horizontal section, in kN; α i is the angle between the bottom surface of the i-th soil strip in the arc segment and the horizontal plane, in degrees; β is the angle between the straight line OB and the normal line of the horizontal sliding surface between the geobag layers, in degrees; is the effective internal friction angle of the i-th soil strip in the arc segment, in degrees; μ is the friction coefficient between geobag layers; γ w is the density of water, in kN / m 3 ;h w is the water depth during flood season, in m; θ is the slope inclination, in °.

[0049] The parameter selection and calculation of the above embankment form, where the horizontal width of the bank slope is set to 1.2m (H≤5) and 1.6m (H>5m), assuming the slope ratio is 1:2.5; according to previous experiments, the calculation formula of the friction coefficient μ between the geobag layers and the vertical pressure P is: μ=-1.93858×10 -5 P 2 +0.00169P+0.67718; effective cohesion of geobag section c r The calculation formula of the bank slope height H1 is: r =82.689H1-6.322.

[0050] The calculation results of the safety factors of Examples 1 to 3 and the original slope are shown in the following table:

[0051]

[0052]

[0053] Safety factor comparison table of Example 1, Example 2, Example 3 and original slope

[0054] Combining the above table and Figure 4 It can be seen that these three types of ecological embankments are all stable (Fs>1.3), and basically show a trend of becoming more and more stable in the order of Example 1, Example 3 and Example 2.

[0055] In summary, the ecological embankment of the present invention can improve the stability of the bank slope and prevent the bank slope from being damaged by scouring during flood season.

[0056] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. 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 water body bank slope ecological embankment structure, characterized by: It includes a reverse osmosis layer, a reinforcement layer and a stone pile structure. The reverse osmosis layer is laid obliquely on the water side of the bank slope, the reinforcement layer is laid obliquely on the reverse osmosis layer, and the stone pile structure is located at the bottom of the water body and pressed on the side of the lower end of the reinforcement layer away from the reverse osmosis layer; the reinforcement layer includes a plant root anchoring layer, and the upper end of the plant root anchoring layer extends to the top of the bank slope.

2. The water body bank slope ecological embankment structure according to claim 1, characterized in that: The reinforcement layer also includes a geobag layer, which is obliquely laid on the reverse osmosis layer. The plant root anchoring layer is distributed on the side of the geobag layer away from the reverse osmosis layer, and the plant root anchoring layer extends into the gap between two adjacent geobags in the geobag layer.

3. The water body bank slope ecological embankment structure according to claim 2 is characterized by: The geobag layer includes a plurality of geobags, which are stacked and arranged, and upper and lower adjacent geobags are staggered.

4. The water body bank slope ecological embankment structure according to claim 3 is characterized by: The geotextile bag is a woven bag made of polypropylene, the weight of the woven bag is 100g / square meter, the tensile strength in the warp and weft directions are 20kN / m and 17kN / m respectively, and the elongation in the warp and weft directions is 18%.

5. The water body bank slope ecological embankment structure according to claim 4, characterized in that: The woven bag is filled with sand, and the internal friction angle of the sand inside each geotextile bag is 22° and the weight is 17kN / m 3 , saturated density is 21.12kN / m 3 .

6. The water body bank slope ecological embankment structure according to claim 5, characterized in that: The filling rate of the geobag is 70-90%.

7. A water body bank slope ecological embankment structure according to any one of claims 1 to 6, characterized in that: The plant root anchoring layer includes native aquatic plants.

Images