CN114197393B - Anti-filtering layer-based hydro-fluctuation belt slope ecological treatment method - Google Patents

Abstract

The invention discloses an ecological treatment method for a water-fluctuation zone slope based on a reverse filter layer, which can effectively protect slope soil particles from loss, provide a stable growth environment for plants in the water-fluctuation zone, and ensure the soil required for vegetation restoration. Maintain the ecological balance of the bank slope and eliminate the bank slope in the water-fluctuation zone caused by the periodic water level fluctuation.

Description

A Method of Ecological Treatment of Fluctuation Zone Slope Based on Reverse Filter Layer

technical field

The invention relates to bank slope treatment in a water-fluctuation zone, in particular to an ecological treatment method for solving water and soil loss in a water-fluctuation zone based on vertical drainage of a reverse filter layer.

Background technique

The ebb zone is a special area where the bank slope is repeatedly inundated due to seasonal water level fluctuations. The vegetation on the water-fluctuation zone becomes sparse through the alternation of dryness and wetness, and the slopes lacking the soil-fixing effect of plant roots are prone to water and soil erosion, which in turn causes the degradation of ecosystem functions, resulting in many ecological problems such as low biodiversity, environmental and visual pollution, etc. , severe cases may even cause geological disasters.

At present, most of the methods for controlling the water-fluctuation zone start with vegetation restoration. This kind of ecological restoration technology can play a certain role in water and soil conservation. It aims to restore the growth of vegetation and restore the ecological balance after the water level drops. It uses the interaction between plants and rock and soil to strengthen the slope, but the slope is often kept as a continuous or mostly continuous inclined plane, so that the soil particles on the slope still have a tendency to slide along the inclined plane. In the process of water level change and rainfall erosion, because the slope protection structure fails to effectively intercept or impede the movement of soil particles on the surface and inside of the slope, some water and soil loss will still occur. After permanent water level fluctuations and rainfall scouring, the slope may be gradually eroded and even lead to the loss of a large number of soil particles, which cannot effectively maintain water and soil for a long time, which will also reduce the effect of vegetation restoration. Therefore, how to essentially avoid water and soil loss is still a current issue The most critical problem is to control the water-fluctuation zone.

Contents of the invention

The problem to be solved by the present invention is to provide a green ecological slope protection method, which can effectively protect the soil particles on the slope surface from loss, provide a stable growth environment for plants in the water-fluctuation zone, ensure the soil required for vegetation recovery, and maintain the slope ecology Balance and eliminate the bank slope of the subduction zone caused by periodic water level fluctuations.

In order to achieve the above object, the present invention provides the following technical solutions:

A method for ecological management of a water-fluctuating zone slope based on a reverse filter layer, comprising the following steps:

Step 1: Slope division

According to the water level data in the wet season and dry season when the water level fluctuates, with the lowest water level as the lower limit and the highest water level as the upper limit, the slope is divided into the highest water level and the lowest water level;

Step 2: Leveling the slope

Remove the sundries on the slope and carry out manual compaction and leveling;

Step 3: Laying Geotextiles

Water-filtering geotextiles are laid and fixed on the slope to make them fully contact with the soil surface;

Step 4: Pouring of permeable concrete retaining wall

During the low water level time in the dry season, perform pervious concrete pouring at the slope toe to obtain a permeable concrete retaining wall;

Step 5: laying the bottom horizontal sand and gravel filter layer

Lay a horizontal sandstone filter layer between the permeable concrete retaining wall and the slope, and control the thickness of the horizontal sandstone filter layer so that its surface height is lower than the height of the retaining wall to reserve a space for planting soil backfill;

Step 6: Place the first level L-shaped drainage board

Place the first-level L-shaped drainage board on the horizontal sandstone filter layer in step 5 and fix it on the side slope. The L-shaped drainage board is composed of a vertical panel and a horizontal panel. It is an impermeable surface, and the horizontal panel is a permeable surface with permeable holes distributed. The horizontal panel of the L-shaped drainage board is placed on the horizontal sandstone filter layer, and the horizontal panel is opposite to the junction of the horizontal panel and the vertical panel. The side of the wall is close to the slope, and the vertical panel and the retaining wall maintain a certain horizontal interval to play the function of filtering soil and drainage;

Step 7: Lay horizontal sand and gravel filter layer

Lay a horizontal sandstone filter layer between the first L-shaped drainage board and the slope, and control the thickness of the horizontal sandstone filter layer so that the surface height is lower than the height of the vertical panel of the L-shaped drainage board to reserve planting soil Backfilled space;

Step 8: Place the second level L-shaped drainage board

Place the second-stage L-shaped drainage board on the horizontal sandstone filter layer in step 7 and fix it on the slope. The horizontal panel of the L-shaped drainage board is placed on the horizontal sandstone filter layer, and the horizontal panel The side opposite to the junction of the horizontal panel and the vertical panel is close to the slope, and the vertical panel maintains a certain horizontal interval with the vertical panel of the first-level L-shaped drainage board;

Step Nine:

Repeat steps 7 and 8 above to place several levels of L-shaped drainage boards step by step along the slope, and lay a horizontal sand and gravel filter layer between each level of L-shaped water retaining board and the side slope until the last level of L-shaped drainage boards. The height of the upper edge of the vertical panel of the drainage board is higher than the highest water level;

Step ten:

On the slope above the highest water level, a medium-fine sand filter layer is laid on the water-filtering geotextile, and the thickness of the medium-fine sand filter layer is controlled to reserve a space for planting soil backfill;

Step 11: Backfilling with planting soil

After placing all the L-shaped drainage boards and completing the slope structure of the part above the highest water level, between the retaining wall and the first-level L-shaped board, between every two-level L-shaped Backfill planting soil on the horizontal fine sandstone filter layer between the vertical panel of the drainage board and the vertical panel of the next-level L-shaped drainage board) and on the slope structure of the part above the highest water level;

Step twelve:

Sow flood-resistant plant seeds in each layer of planting soil, and maintain until the vegetation takes root and grows to have a certain soil-fixing ability, that is, the construction of ecological green slope protection in the water-fluctuation zone is completed.

Preferably, the slope angle of the side slope of the hydrofluctuation zone is 30-45°.

Preferably, the geotextile is a water-filtering geotextile, and its overlapping joints are welded or stitched to form an integral structure. The thickness of the geotextile is between 1.5 and 5 mm, and the equivalent diameter is less than 0.075 mm. Preferably, the fixing method of the geotextile on the slope is as follows: the top and bottom ends of the geotextile are fixed on the slope with anti-skid nails.

As preferably, the structural section of the permeable concrete retaining wall is a right-angled trapezoid with a height of 600-800mm to consolidate the slope foot. As a preference, the self-strength of the permeable concrete needs to be able to meet the strength requirements of C20-C25 ordinary concrete, and has a porosity of 15%-25%, has high water permeability, and can filter soil for drainage. As a further preference, the permeable concrete adopts ecological cement to provide a low-alkali environment, which makes surrounding plants more suitable for growth and also protects water quality.

Preferably, the horizontal sandstone filter layer is composed of a horizontal medium fine sandstone filter layer and a horizontal fine sandstone filter layer, and the horizontal medium fine sandstone filter layer is placed under the horizontal fine sandstone filter layer . It is further preferred that the gradation of the fine sand should meet the Terzaghi filter soil criterion according to the gradation of the protected soil (ie slope soil), that is, according to D ₁₅ /d ₈₅ ≤ 4 and D ₁₅ /d ₁₅ ≥ 4 Determine the particle size _D15 range of the fine sand, where _D15 is the particle size of the fine sand filter layer, which is defined as the weight of the soil less than this particle size in the fine sand filter layer accounts for 15% of the total soil weight; d ₈₅ is the particle size of the protected soil (that is, the slope soil), which is defined as the weight of the soil smaller than this particle size in the slope soil accounts for 85% of the total soil weight; d ₁₅ is the particle size of the protected soil (that is, the slope soil), which is defined as The weight of the soil smaller than this particle size in the slope soil accounts for 15% of the total soil weight. It is further preferred that the gradation of the medium and fine sand should meet the Terzaghi filter soil criterion according to the gradation of the protected soil (ie, the fine sand filter layer), that is, according to D ₁₅ /d ₈₅ ≤ 4 and D ₁₅ / d ₁₅ ≥ 4 Determine the particle size D ₁₅ range of medium and fine sand, where D ₁₅ is the particle size of the medium and fine sand filter layer, which is defined as the weight of soil smaller than this particle size in the medium and fine sand filter layer in the total soil 15% of the weight; d ₈₅ is the particle size of the protected soil (that is, the fine sand filter layer), which is defined as the weight of the soil smaller than this particle size in the fine sand filter layer accounts for 85% of the total soil weight; d ₁₅ is the particle size of the protected soil The particle size of the protective soil (that is, the fine sand filter layer) is defined as the weight of the soil smaller than this particle size in the fine sand filter layer accounts for 15% of the total soil weight. In order to avoid clogging and achieve the drainage effect, the mud content of medium and fine sandstone and fine sandstone should be less than 3%, and the part with a particle size of less than 2mm should not exceed 45% of the total weight, and it does not contain plant residues, Impurities such as garbage.

As a preference, at the foot of the slope, the thicknesses of the horizontal medium-fine sand filter layer and the horizontal fine sand filter layer are 300-400 mm respectively, and the thickness should be smaller when the slope angle is larger, which is conducive to the stability of the overall structure; In each level of L-shaped drainage boards, the thickness of the horizontal medium-fine sand filter layer and the horizontal fine sand filter layer are 200-300mm, and the thickness should be smaller when the slope angle is larger, which is beneficial to the overall structure. Stablize.

As a preference, the L-shaped drainage board is made of ABS engineering plastic, which is light, high-strength, strong in corrosion resistance and non-toxic; the longitudinal length of the vertical panel of the L-shaped drainage board, the horizontal and vertical lengths of the horizontal panel Both are 600-700mm, and the plate thickness is 20-30mm; the junction of the horizontal panel and the vertical plate surface forms a smooth curved surface, and stiffeners are arranged on the structure to further strengthen the structural resistance. A certain horizontal interval should be kept between the vertical panel of the L-shaped drainage board and the permeable concrete retaining wall and between the vertical panels of the adjacent two-stage L-shaped drainage board. Generally speaking, when the slope angle The larger the value, the smaller the horizontal spacing should be, which is conducive to the stability of the overall structure.

As a preference, the L-shaped drainage board is fixed on the slope through the permeable holes of the horizontal panel with wooden stakes or bamboo stakes to improve the overall stability, and the use of wooden stakes or bamboo stakes has no pollution to the slope environment, and more Conducive to ecological balance.

As a preference, the height of the upper edge of the vertical panel of the last L-shaped drainage board is higher than the highest water level and the vertical distance from the highest water level is within 200mm.

As a preference, on the slope above the highest water level, a vertical fine sand and gravel filter layer is laid at every certain distance (for example, 2000-3000mm) as a water intercepting ditch.

Preferably, in step ten, the vertical thickness of the medium-fine sand and gravel filter layer on the slope above the highest water level relative to the slope is 200-300mm.

Preferably, in the eleventh step, the planting surface is made into a smooth concave surface.

Preferably, the flood-tolerant plant is one or any combination of Bermudagrass, Verbena, Green Thatch, Sweet Root and Bahia Grass.

The present invention has the following beneficial effects:

(1) According to the increase of water level, rationally divide and set up the slope in a targeted manner, effectively and reasonably deal with the problem of water level fluctuation, and be economical and safe.

(2) Transform the slope into a ladder-like structure, carry out segmental rapid vertical drainage based on the filter layer, and guide the water to the permeable concrete retaining wall through the medium-fine sand filter layer in the lower layer. During this process, the present invention changes the traditional scouring and splashing form of rainwater on the slope surface during rainfall into a vertical precipitation form, which essentially limits the horizontal movement of soil particles, avoids soil erosion on the slope surface, and Under the action of multi-layer reverse filter layer, rapid filter soil drainage is realized to prevent seepage damage caused by stagnant water in the upper layer.

(3) The L-shaped drainage board adopted in the present invention is light in weight and high in strength, and can provide a good drainage and water-proof effect. It can treat the slope layeredly, and carry out ladder-shaped layering of different layers of soil for independent precipitation. The L-shaped The drainage board is higher than the planting surface, which effectively limits the horizontal displacement of soil particles. The cost of the L-shaped drainage board is low, it can be mass-produced, and the construction operation is simple.

(4) Plant flood-resistant plants in the planting soil, and further consolidate the bank slope soil through the root system of the plants to prevent soil erosion. Durability provides the conditions. After the water level drops, the reverse filter system will cause small-scale clogging due to the retention of some soil particles, such as fine soil particles staying inside the reverse filter layer to cause clogging, or gathering on the surface of the reverse filter layer to form blockage, these All problems will cause the permeability coefficient of the reverse filter layer to gradually decrease, thereby affecting the filter soil drainage effect of the reverse filter system. The fine sandstone filter layer of the present invention is placed on the medium fine sandstone layer. When the water level rises, the water flow will also enter the drainage channel from the permeable concrete retaining wall to scour each filter layer. Further, it will cause To the effect of dredging, keep the filter system in the present invention working for a long time.

(5) In the case of a rapid drop in water level or a sudden rainstorm, the formed water flow is limited by the water-repelling surface of the L-shaped plate when passing through the planting surface, and only vertical infiltration parallel to the water-repelling surface can occur. In the lower layer of the protected soil, a first layer of fine sand and gravel filter layer is set, and the particle size is reasonably selected so that the largest particles moved in the protected soil can easily form an arch at the outlet of the filter layer, preventing other particles from continuing to filter. It enters the reverse filter layer and plays the role of soil filter. The particle size of the medium and fine sand filter layer in the second layer is larger than that of the upper sand filter layer, and forms a reliable and stable soil structure with it without relative sliding, providing sufficient drainage channels and sufficient drainage capacity to achieve rapid drainage In the case of rising water level, soil particles do not move with the water flow due to their own weight and upper resistance, and the water flow in the filter system quickly passes through the structural gap of the filter layer to reach the same level as the external water level, reducing the impact of water head difference on the slope. adverse effects.

Description of drawings

Fig. 1 is the overall sectional schematic diagram of the present invention;

Fig. 2 is a partial cross-sectional schematic diagram of the present invention;

Fig. 3 is the L-shaped drainage board schematic diagram that the present invention adopts;

Fig. 4 is the schematic diagram of water flow movement inside the slope protection structure of the present invention under the conditions of water level variation and rainfall;

Fig. 5 is a schematic diagram of the local water level of the present invention under the conditions of water level variation and rainfall;

Reference signs:

1—Geotextile

2—Medium and fine sand reverse filter layer

3—Fine sand and gravel reverse filter layer

4—Permeable concrete retaining wall

5—planting soil

6—L-shaped drainage board

7—Flood Tolerant Plants

8—at the lowest water level

9—Water level rise

10—Highest water level

11—Interception ditch

12—Water movement direction

13—Water level line outside the slope

14—Water level line in slope protection structure

A—permeable surface

B—impermeable surface

C—stiffener.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments, and the given examples are only used to explain the present invention, and are not intended to limit the scope of the present invention.

Referring to accompanying drawing 1 to 3, a kind of method for ecological management of the water-fluctuation zone slope based on the reverse filter layer, the slope angle of the water-fluctuation zone slope is 30-45 °, and its construction method comprises the following steps:

Step 1: Slope division

According to the water level data, with the lowest water level as the lower limit and the highest water level as the upper limit, the slope is divided into 10 points for the highest water level and 8 points for the lowest water level.

Step 2: Leveling the slope

Remove garbage, stones, turf, tree roots and other sundries on the slope, and carry out manual compaction and leveling. According to the local conditions, the interception ditch at the top of the slope and the drainage ditch on the slope surface can be constructed to form a complete water interception and drainage system in the entire construction area, which is convenient for the construction of slope protection works.

Step 3: Laying Geotextiles

Water-filtering polyester filament geotextile 1 is laid on the slope, fully in contact with the soil surface, and the top and bottom of the geotextile are fixed with anti-slip nails, and the lap joints need to be welded or stitched to form an overall structure . Step 4: Pouring of permeable concrete retaining wall

During the low water level time in the limited dry season, wooden plywood formwork support should be carried out at the foot of the slope, and C20 permeable concrete should be poured. The structural section of the permeable concrete retaining wall is a right-angled trapezoid with a height of 600-800mm to consolidate the slope. Feet, poured permeable concrete retaining wall 4, sprinkle water and wait for its strength to reach more than 75% of the design strength, and then further construction.

Step 5: laying the bottom horizontal sand and gravel filter layer

Between the permeable concrete retaining wall at the foot of the slope and the slope, lay the horizontal medium-fine sand filter layer 2 and the horizontal fine sand filter layer 3 on the water-filtering geotextile 1, and the medium-fine sand filter layer 2 Place under the horizontal fine sand filter layer 3, and control the total thickness of the horizontal medium fine sand filter layer 2 and the horizontal fine sand filter layer 3 to be lower than the height of the retaining wall to reserve space for planting soil backfill , wherein the thickness of the medium and fine sand filter layer is 300-400mm, and the thickness of the fine sand filter layer is 300-400mm. Water-filtering geotextiles 1 are used to separate each layer of sand filter layers to prevent The mixture of two particle sizes affects the drainage effect of filter soil. The gradation of the fine sand should meet the Terzaghi filter soil criterion according to the gradation of the protected soil (i.e. slope soil), that is, according to D ₁₅ /d ₈₅ ≤ 4 and D ₁₅ /d ₁₅ ≥ 4 D ₁₅ range of particle size of fine sand, where D ₁₅ is the particle size of the fine sand filter layer, which is defined as the soil weight smaller than this particle size in the fine sand filter layer accounts for 15% of the total soil weight; d ₈₅ is The particle size of the protected soil (i.e. slope soil) is defined as the soil weight smaller than this particle size in the slope soil accounts for 85% of the total soil weight; d ₁₅ is the particle size of the protected soil (i.e. slope soil), which is defined as The weight of soil smaller than this particle size in slope soil accounts for 15% of the total soil weight. The gradation of the medium and fine sand should meet the Terzaghi filter soil criterion according to the gradation of the protected soil (ie, the fine sand filter layer), that is, according to D ₁₅ /d ₈₅ ≤ 4 and D ₁₅ /d ₁₅ ≥4 to determine the particle size D ₁₅ range of medium and fine sand, where D ₁₅ is the particle size of the medium and fine sand filter layer, which is defined as the percentage of the soil weight smaller than this particle size in the total soil weight in the medium and fine sand filter layer 15%; d ₈₅ is the particle size of the protected soil (that is, the fine sand filter layer), which is defined as the weight of the soil smaller than this particle size in the fine sand filter layer accounts for 85% of the total soil weight; d ₁₅ is the protected soil (i.e. fine sand filter layer) particle size, defined as the fine sand filter layer less than the particle size of the soil weight accounted for 15% of the total soil weight. In order to avoid silting and achieve the drainage effect, the mud content of medium and fine sand and fine sand should be less than 3%, and the part with a particle size of less than 2mm should not exceed 45% of the total weight, and neither plant residues nor garbage and other impurities.

Step 6: Place the first level L-shaped drainage board

The L-shaped drainage board is made of ABS engineering plastics, and is composed of a vertical panel and a horizontal panel. The thickness is 20-30mm; the vertical panel is an impermeable surface, while the horizontal panel has several circular permeable holes that are beneficial to seepage. The junction of the horizontal panel and the vertical panel forms a smooth curved surface. Set up stiffeners. After laying the horizontal sandstone filter layer, the first-stage L-shaped drainage board 6 is placed on the horizontal fine sandstone filter layer 3, and the side opposite to the junction of the horizontal panel and the vertical panel on the horizontal panel is closely attached. slope. Fix the L-shaped drainage board on the slope with wooden stakes or bamboo stake nails through the round holes of the horizontal panel.

Step 7: Lay horizontal sand and gravel filter layer

According to the operation of step five, a horizontal medium-fine sand filter layer with a thickness of 200-300mm and a horizontal fine-grain filter layer with a thickness of 200-300mm are laid between the first-level L-shaped drainage board and the slope.

Step 8: Place the second level L-shaped drainage board

According to the operation of step six, place the second-stage L-shaped drainage board on the horizontal fine sand filter layer in step seven and fix it on the side slope.

Step Nine:

Repeat steps 7 and 8 above to place several L-shaped drainage boards step by step along the slope until the upper edge of the vertical panel of the last L-shaped drainage board is higher than the highest water level and the vertical distance from the highest water level is 200mm Inside.

Step ten:

The slope above the highest water level is mainly to prevent soil erosion caused by rainwater erosion. The construction method should first lay medium-fine sand with a thickness of 200-300mm (relative to the vertical thickness of the slope) on the filter geotextile 1. For the stone filter layer, a vertical fine sand filter layer is laid on the slope at intervals of 2000-3000mm as the intercepting ditch 11.

Step 11: Backfilling with planting soil

For the part below the maximum water level, after placing all the L-shaped drainage boards 6, between the retaining wall and the first-level L-shaped water-retaining board, between two adjacent L-shaped water-retaining boards, and on the slope above the highest water level line Backfill the planting soil 5 on the medium-fine sand filter layer of surface structure, and make the planting surface into a smooth concave surface, and sow flood-resistant plant seeds in each layer of planting soil 5 by spraying technology, and maintain until the vegetation Rooting and growth has a certain soil-fixing ability, that is, the construction of ecological green slope protection in the water-fluctuation zone is completed.

Example 1:

Referring to the above-mentioned construction method, this embodiment is used for the slope test section of the Kuwan subgrade section YK22+730-YK22+970 of Qianhuang Expressway YK22+730-YK22+970 in Chun'an County, Hangzhou City, Zhejiang Province. The length of the test section is 100m. The embankment fills the side slope, the north side is close to the expressway road, the south side is adjacent to the lake, the east side intersects with another side slope, and the west side is the extension of the side slope. The total height of the slope is about 28m, which is divided into three levels of filling. The first level of slope is about 8m high with a slope ratio of 1:2.00; the second level of slope is about 12m high with a slope ratio of 1:1.75; About 8m, the slope ratio is 1:1.50, and there is a 2m wide platform at the junction of every two grades of slopes.

The area is warm and humid, with abundant rainfall and sunshine. The average annual precipitation is 1100-1600 mm, mainly in spring rain, plum rain and typhoon. The perennial plum rainfall can reach 350-550mm, accounting for 25-31% of the annual rainfall. The most rainy days in history in one year is 155 days. The maximum annual rainfall is 2111.4mm, the minimum is 1025.4mm, the maximum monthly rainfall is 245.5mm, and the maximum daily rainfall is 147mm. The water level basically shows a low water level of 98-100m from January to March, gradually rising to 104m from April to June, a high water level of 105-108m from July to September, and gradually falling back to a low water level of 100m from October to December. Year-to-year dynamics. During the dry season in winter, the lowest water level is about 98m (i.e. the foot of the slope), and in the flood season in summer, the water level can reach 108m, and the fluctuation of water level is as high as 10m.

In this embodiment, 108m and 98m are regarded as the highest water level 10 and the lowest water level 8 of the slope protection respectively, and the following slope protection construction operations will be completed before May 2020:

(1) Leveling the slope: According to the design, manually level the slope, remove debris, and manually compact and level;

(2) Pouring slope foot: Set up wooden plywood formwork for C30 permeable concrete pouring operation, forming a right-angled trapezoidal permeable concrete retaining wall with a vertical section size of 800mm×300mm×600mm (height×upper bottom×lower bottom) 4 Consolidate the slope foot;

(3) Laying of geotextiles: Use 350g (that is, 350g per square meter) water-filtering polyester filament geotextiles 1 to lay on the slope, and manually roll from bottom to top to maintain a certain degree of tightness. , There are anti-skid nails on the bottom and the slope, and the weight will be pressed along with the laying, and the overall structure must be formed by sewing at the overlapping joints;

(4) Sand and gravel material selection: The key particle size is obtained through the indoor particle test of the field soil samples, in which the field soil samples d ₁₅ = 1.96mm, d ₈₅ = 12.51mm, combined with Terzaghi filter soil criteria and drainage criteria D ₁₅ ≤ 4×d ₈₅ ＝4×12.51＝50.04mm, D ₁₅ ≥4×d ₁₅ ＝4×1.96＝7.84mm, it can be seen that the effective particle size D ₁₅ distribution range of the fine sand and stone reverse filter layer 3 should be 7.84-50.04 mm, in the same way, if the fine sand filter layer 3 is used as the fine sand filter layer 2 in the design of the protective soil, the effective particle size D ₁₅ distribution range of the medium fine sand filter layer 2 should be 31.36-200.16 mm, the mud content of medium and fine gravel and fine gravel should be less than 3%, and the part with a particle size of less than 2mm should not exceed 45% of the total weight, and it does not contain impurities such as plant residues and garbage. The sand and gravel filter materials all meet the above requirements;

(5) Laying of sand and gravel filter layer: the laying thickness of the fine sand filter layer 3 and medium-fine sand filter layer 2 between the retaining wall and the first-stage L-shaped water retaining plate is 300mm, and the The laying thickness of the fine sand filter layer 3 and the medium fine sand filter layer 2 between the L-shaped water retaining boards is 200mm, and the laying sequence is first the medium fine sand filter layer 2 and then the fine sand filter layer Layer 3, since the reverse filter material used this time is inhomogeneous material, the middle-fine sand filter layer 2 and the fine sand filter layer 3 may not be divided by geotextiles;

(6) Placement of L-shaped drainage board: The L-shaped drainage board is made of ABS engineering plastics, and is composed of a vertical panel and a horizontal panel. The longitudinal length is 600mm, and the plate thickness is 20mm; the vertical panels are impermeable surfaces, while the horizontal panels have several circular permeable holes that are beneficial to seepage, and the junction of the horizontal panels and the vertical panels is smooth. A curved surface with stiffeners placed on its structure. Place the first-stage L-shaped drainage board 6 on the horizontal fine sand and stone reverse filter layer 3, and the side of the horizontal panel opposite to the junction of the horizontal panel and the vertical panel is close to the slope, and wooden stakes or bamboo stakes are used to pass through The round hole of the horizontal panel fixes the L-shaped drainage board on the slope;

(7) According to (5) and (6), repeat the construction of the fine sand reverse filter layer 3, the medium fine sand reverse filter layer 2 and the L-shaped drainage board 6 until reaching the highest water level line 10; the slope above the highest water level line 10 Lay a medium-fine sandstone filter layer with a thickness (relative to the vertical thickness of the slope) of 200mm (refer to step (5) for medium-fine sandstone particle size selection), and lay a vertical fine-grain filter layer at an interval of 2000mm ( The particle size of fine gravel is selected with reference to step (5)) as the intercepting ditch 11;

(8) Backfill the planting soil, and make the planting surface into a smooth concave surface, sow the seeds of flood-tolerant plants in each layer of planting soil, and choose vetiver, Arundis mosaicus, Bermudagrass and bahia grass as experiments The flood-tolerant plants in the section, among them, vetiver and Arundis mosaic are transplanted, and Bermudagrass and bahia grass are planted on the slope by spraying, and then watered and maintained, fertilized and replanted regularly, and the edge is completed. slope construction.

Randomly select 2 measuring points on the slope surface of the test section and 2 measuring points on the bare slope surface as the research objects, and use the particle test to obtain the initial soil particle size distribution. Soil samples were obtained from 4 measuring points for particle tests, and the ratio of the mass of soil particles with different particle sizes to the total weight of the soil samples at each measuring point was obtained. Measuring points 1 and 2 are the measuring points on the slope of the test section, and measuring point 3 And measuring point 4 is the measuring point on the bare slope surface, and the comparison results are shown in Table 1 below.

Table 1 Particle score results at three measuring points on the slope in May 2020 and July 2021

Taking the particle size of 4.75 mm as the dividing line, it can be found that after a long period of water level fluctuations, although there is a certain amount of fine particle loss at measuring points 1 and 2 in the test section, the soil particles smaller than 4.75 mm have the largest change amplitude About 4%, the maximum change amplitude of soil particles greater than or equal to 4.75mm is about 4.26%; there is a significant loss of fine particles at measurement points 3 and 4 of the bare slope section, and the change amplitude of soil particles smaller than 4.75mm is the largest It is about 10.44%, and the variation amplitude of the soil particles greater than or equal to 4.75mm is about 13.97%. Seen from the cumulative loss ratio of fine particles (only considering the particle size below 4.75mm), the cumulative loss of fine particles in the test section is 6-8%, and the bare slope section reaches 19%. The ecological management method of belt slope can slow down soil erosion to a certain extent, and with green flood-tolerant plants, it can play the role of ecological green restoration, and then control the problem of water-fluctuation zone.

Apparently, the above embodiments only illustrate the technical solutions of the present invention rather than limit them. The present invention has been described in detail through the above embodiments, but those skilled in the art can make reasonable and effective changes in the forms and details.

Claims (10)

1. A method for ecological management of a water-fluctuating zone slope based on a reverse filter layer, comprising the following steps: Step 1: Slope division According to the water level data in the wet season and dry season when the water level fluctuates, with the lowest water level as the lower limit and the highest water level as the upper limit, the slope is divided into the highest water level and the lowest water level; Step 2: Leveling the slope Remove the sundries on the slope and carry out manual compaction and leveling; Step 3: Laying Geotextiles Water-filtering geotextiles are laid and fixed on the slope to make them fully contact with the soil surface; Step 4: Pouring of permeable concrete retaining wall During the low water level time in the dry season, perform pervious concrete pouring at the slope toe to obtain a permeable concrete retaining wall; Step 5: laying the bottom horizontal sand and gravel filter layer Lay a horizontal sandstone filter layer between the permeable concrete retaining wall and the slope, and control the thickness of the horizontal sandstone filter layer so that its surface height is lower than the height of the retaining wall to reserve a space for planting soil backfill; Step 6: Place the first level L-shaped drainage board Place the first-level L-shaped drainage board on the horizontal sandstone filter layer in step 5 and fix it on the side slope. The L-shaped drainage board is composed of a vertical panel and a horizontal panel. It is an impermeable surface, and the horizontal panel is a permeable surface with permeable holes distributed. The horizontal panel of the L-shaped drainage board is placed on the horizontal sandstone filter layer, and the horizontal panel is opposite to the junction of the horizontal panel and the vertical panel. The side of the wall is close to the slope, and the vertical panel and the retaining wall maintain a certain horizontal interval to play the function of filtering soil and drainage; Step 7: Lay horizontal sand and gravel filter layer Lay a horizontal sandstone filter layer between the first L-shaped drainage board and the slope, and control the thickness of the horizontal sandstone filter layer so that the surface height is lower than the height of the vertical panel of the L-shaped drainage board to reserve planting soil Backfilled space; Step 8: Place the second level L-shaped drainage board Place the second-stage L-shaped drainage board on the horizontal sandstone filter layer in step 7 and fix it on the slope. The horizontal panel of the L-shaped drainage board is placed on the horizontal sandstone filter layer, and the horizontal panel The side opposite to the junction of the horizontal panel and the vertical panel is close to the slope, and the vertical panel maintains a certain horizontal interval with the vertical panel of the first-level L-shaped drainage board; Step Nine: Repeat steps 7 and 8 above to place several levels of L-shaped drainage boards step by step along the side slope, and lay a horizontal sand and gravel filter layer between each level of L-shaped drainage board and the side slope until the last level of L-shaped drainage The height of the upper edge of the vertical panel of the slab is higher than the highest water mark; Step ten: On the slope above the highest water level, a medium-fine sand filter layer is laid on the water-filtering geotextile, and the thickness of the medium-fine sand filter layer is controlled to reserve a space for planting soil backfill; Step 11: Backfilling with planting soil After placing all the L-shaped drainage boards and completing the slope structure above the highest water mark, between the retaining wall and the first L-shaped slab, between every two L-shaped slabs and the part above the highest water mark Backfill the planting soil on the slope structure; between each two levels of L-shaped slabs refers to the horizontal detail between the vertical panel of the upper-level L-shaped drainage panel and the vertical panel of the lower-level L-shaped drainage panel. On the sand filter layer; Step twelve: Sow flood-resistant plant seeds in each layer of planting soil, and maintain until the vegetation takes root and grows to have a certain soil-fixing ability, that is, the construction of ecological green slope protection in the water-fluctuation zone is completed. 2. The method for ecological management of the water-fluctuation zone slope based on the filter layer as claimed in claim 1, characterized in that: the slope angle of the water-fluctuation zone slope is 30-45°. 3. The method for ecological management of the water-fluctuating zone slope based on the reverse filter layer as claimed in claim 1, wherein the geotextile adopts a water-filtering geotextile, and its lap joints form a whole by welding or sewing structure, the thickness of the geotextile is between 1.5-5mm, and the equivalent diameter is less than 0.075mm; the fixing method of the geotextile on the slope is: the top and bottom of the geotextile are fixed on the slope with anti-skid nails. 4. The method for ecological management of the water-fluctuating zone slope based on the reverse filter layer as claimed in claim 1, characterized in that: the structural section of the permeable concrete retaining wall is a right-angled trapezoid, and its height is 600-800mm, to consolidate Slope toe; the self-strength of the permeable concrete needs to be able to meet the strength requirements of C20-C25 ordinary concrete, and have a porosity of 15%-25%. 5 . The method for ecological management of the water-fluctuating zone slope based on the filter layer as claimed in claim 4 , wherein the permeable concrete adopts ecological cement. 6 . 6. The method for ecological management of the water-fluctuating zone slope based on the reverse filter layer as claimed in claim 1, characterized in that: the horizontal sandstone filter layer is composed of a horizontal medium fine sandstone filter layer and a horizontal fine sandstone reverse filter layer. filter layer, and the horizontal medium-fine sand filter layer is placed under the horizontal fine sand filter layer; The gradation of the fine sand and gravel satisfies the Terzaghi filter soil criterion according to the gradation of the protected soil, that is, the slope soil, that is, the fine sand and gravel are determined according to D ₁₅ /d ₈₅ ≤ 4 and D ₁₅ /d ₁₅ ≥ 4 The range of particle size D ₁₅ , where D ₁₅ is the particle size of the fine sand filter layer, which is defined as the soil weight smaller than this particle size in the fine sand filter layer accounts for 15% of the total soil weight; d ₈₅ is the protected soil That is, the particle size of the slope soil, which is defined as the soil weight smaller than the particle size in the slope soil accounting for ₈₅ % of the total soil weight; Soil weight accounts for 15% of the total soil weight; The gradation of the medium and fine sand should meet the Terzaghi filter soil criterion according to the gradation of the protected soil, that is, the fine sand filter layer, that is, it should be determined according to D ₁₅ /d ₈₅ ≤4 and D ₁₅ /d ₁₅ ≥4 The particle size _D15 range of medium and fine sand, where _D15 is the particle size of the medium and fine sand filter layer, which is defined as the weight of soil less than this particle size in the medium and fine sand filter layer accounts for 15% of the total soil weight; d ₈₅ is the particle size of the protected soil, that is, the fine sand and gravel filter layer, which is defined as the weight of soil smaller than this particle size in the fine sand and gravel filter layer accounts for 85% of the total soil weight; d ₁₅ is the protected soil, that is, fine sand and gravel The particle size of the filter layer is defined as 15% of the total soil weight in the filter layer of fine sand and gravel smaller than the particle size; The mud content of the medium-fine sand and fine sand should be less than 3%, and the part with a particle diameter of less than 2mm should not exceed 45% of the total weight, and should not contain impurities. 7. the method for ecological management of the water-fluctuating zone slope based on the filter layer as claimed in claim 6, characterized in that: at the foot of the slope, the thickness of the horizontal medium fine sand filter layer and the horizontal fine sand filter layer They are 300-400mm respectively; in each level of L-shaped drainage board, the thicknesses of the horizontal medium-fine sand filter layer and the horizontal fine sand filter layer are 200-300mm respectively. 8. the method for ecological management of the water-fluctuating zone slope based on the reverse filter layer as claimed in claim 1, characterized in that: the L-shaped drainage board adopts ABS engineering plastics; the vertical panel of the L-shaped drainage board The longitudinal length of the horizontal panel and the horizontal and vertical length of the horizontal panel are both 600-700mm, and the plate thickness is 20-30mm; the junction of the horizontal panel and the vertical panel forms a smooth curved surface, and stiffeners are arranged on the structure. 9. as claimed in claim 1 or 8, based on the water-fluctuating zone slope ecological treatment method of the reverse filter layer, it is characterized in that: said L-shaped drainage plate is fixed on on the slope. 10. The method for ecological management of the water-fluctuating zone slope based on the reverse filter layer as claimed in claim 1, characterized in that: on the slope above the highest water level, a vertical fine sand filter is laid every certain distance layers as intercepting ditches.