A curved geogrid ecological slope protection structure and construction method

Abstract

The present invention discloses a curved geogrid ecological slope protection structure and a construction method thereof. The ecological slope protection structure mainly includes a road surface, and a slope provided on the inner subgrade of the road surface or the outer subgrade of the road surface. A plurality of rectangular grid beams anchored by anchor bolts are provided on the slope surface of the slope, and in each grid beam, a lower geogrid, planting soil with a curved geogrid in the middle, and an outer sealed geotextile are sequentially laid on the slope surface from the inside to the outside. The lower geogrid and the curved geogrid are fixed on the slope by multiple anchor nails, and plant seeds required for forming vegetation are added to the surface layer of the planting soil. Therefore, this ecological slope protection structure has the advantages of simple structure, economic savings, ecological environmental protection, safety and reliability in use, can better reflect the concept of green engineering construction, and combined with the corresponding construction method, it also has high economic benefits, energy conservation and environmental protection benefits and social benefits.

Description

Technical Field

[0001] The present invention relates to the field of ecological road construction, and particularly to a curved geogrid ecological slope protection structure and a construction method thereof. Background Art

[0002] In order to achieve long-term stability of road slopes and quickly restore the damaged slope ecosystem, the ecological protection technology of using plants combined with civil engineering measures for road slope protection has been rapidly developed. The ecological protection technology for road slopes is an ecological technology with self-supporting, self-organizing, and self-repairing characteristics. There are many types of this technology, such as soil spraying, aggregate spraying, three-dimensional geonet spraying and seeding, hot-dip galvanized wire mesh, etc. However, the grid materials used for these slope ecological protections are all arranged parallel to the slope surface, resulting in a single and relatively weak contact surface form between the grid material and the planting soil, poor friction and bonding effects. During the operation period, the planting soil is washed by rain or fragmented due to drought, and it is easy to occur phenomena such as the dropping and falling of the planting soil, especially in the initial stage when the roots of the slope vegetation have not yet grown and developed, which not only affects the slope protection effect but also endangers the slope structure safety or is prone to induce road traffic accidents. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a curved geogrid ecological slope protection structure and a construction method thereof that are simple in structure, economical, ecological and environmentally friendly, safe and reliable.

[0004] The technical problem of the present invention is realized through the following technical solutions:

[0005] A curved geogrid ecological slope protection structure includes a road surface and a slope provided on the inner subgrade of the road surface or the outer subgrade of the road surface. A plurality of rectangular frame beams anchored by anchor bolts are arranged on the slope surface of the slope. Each of the frame beams is provided with a lower geogrid, planting soil with an inner curved geogrid, and an outer-sealed geotextile that are sequentially laid on the slope surface from the inside to the outside; the lower geogrid and the curved geogrid are fixed on the slope by a plurality of anchor nails; plant seeds required for forming vegetation are added to the surface layer of the planting soil.

[0006] The oblique length of the curved geogrid from the upper border of the frame beam to the lower border of the frame beam is in the form of a cosine function curve and is laid on the slope surface of the slope; the planting soil contains an inner curved geogrid, and the thickness and specific gravity of the planting soil are respectively , , and the friction and bonding coefficients between the planting soil and the top and bottom surfaces of the curved geogrid are , and the friction and bonding coefficients between the planting soil and the top surface of the lower geogrid are , the following calculation formula is obtained based on the principle of force balance:

[0007] Formula 1:

[0008] The relevant parameters and curve equation of the curved geogrid are:

[0009]

[0010] Formula 2:

[0011] In the early stage when the roots of vegetation on the slope have not yet grown and developed, when the planting soil is in the most unfavorable condition of saturated water content, the planting soil slides along the slope surface line, and the tension acting on the fixing points of the curved geogrid and the upper and lower frames of the frame beams is

[0012]

[0013] When only the upper and lower ends of the curved geogrid are fixed to the frame beam with anchors, , then

[0014]

[0015] When the curved geogrid is fixed by multiple anchors, the tension of the curved geogrid between two adjacent anchors at the anchors is calculated according to the principle of Formula 2; The curved geogrid fixed by the root anchor, the upper frame of the frame beam and the lower frame of the frame beam, Solving the system of equations Tension at the root anchor, where the tension at the fixed point of the curved geogrid and the lower frame of the frame beam is equal to zero;

[0016] Formula 3:

[0017] The sum of vertical friction and cohesion between the curved geogrid and the planting soil is greater than that between the straight lower geogrid and the planting soil, and is calculated as follows:

[0018]

[0019] The symbols in Formula 1, Formula 2 and Formula 3 are defined as:

[0020] ——respectively the width of the planting soil and the curve of the curved geogrid one Cycle in The length on the axis, ;

[0021] ——are the self-weight load of the planting soil acting on the curved geogrid, Axial tangential load, axial normal load, ;

[0022] —— are respectively the friction and bonding coefficients between the planting soil and the top surface of the lower geogrid, and the friction and bonding coefficients between the planting soil and the top and bottom surfaces of the curved geogrid, obtained through tests and can be obtained by referring to relevant materials in the preliminary design stage; since the friction and bonding forces of the top and bottom surfaces of the curved geogrid are greater than those of the straight-line single-sided lower geogrid, and the angle between the friction force direction of the curved geogrid and the sliding direction of the planting soil is 90 0 i.e., perpendicular, which can more effectively block the sliding of the planting soil, so the friction and bonding forces are comprehensively increased, that is , which is more beneficial for the initial stage when the roots of the slope vegetation have not yet grown and developed, dimensionless;

[0023] —— are respectively the angle between the slope surface and the horizontal plane, and the angle between the curved geogrid at any point and the horizontal plane, ;

[0024] —— are respectively the number of anchor nails for fixing the curved geogrid, and the number of cosine curve periods of the curved geogrid between the upper and lower frames of the grid beam;

[0025] —— are respectively the friction and bonding forces between the curved geogrid at any point and the planting soil, the vertical component of the friction and bonding forces between the curved geogrid at any point and the planting soil, the friction and bonding forces between the straight-line lower geogrid at any point and the planting soil, and the vertical component of the friction and bonding forces between the straight-line lower geogrid at any point and the planting soil, ;

[0026] —— is the ratio of the total vertical component of the friction and bonding forces between the curved geogrid and the planting soil to the total friction and bonding forces between the straight-line lower geogrid and the planting soil, dimensionless;

[0027] —— are respectively the tensile forces at the fixed points of the unit-width curved geogrid with the upper and lower frames of the grid beam, and the allowable tensile force of the unit-width curved geogrid, .

[0028] The described curved geogrid is arranged in a curved shape in the planting soil, and the curved geogrid is a cosine curve Or a parabola or other curves that satisfy the boundary conditions.

[0029] The lower geogrid and the curved geogrid are steel-plastic geogrids laid on the slope surface, or rust-proof treated metal wire meshes or non-metal wire meshes.

[0030] Multiple anchor nails are made of steel. Each anchor nail is made into a 7-shaped shape from round steel bars with a diameter of 8 mm to 10 mm, with a length of 2 m to 5 m, and is equipped with auxiliary binding wires to fix the lower geogrid and the curved geogrid, and multiple anchor nails are arranged in a plum blossom shape.

[0031] The geotextile is a needle-punched non-woven geotextile material made of polyester staple fibers; the planting soil is an organic soil mixture of soil spraying or aggregate spraying with added plant seeds.

[0032] The road surface is the road surface course; the slope is formed by filling or excavation of the inner subgrade or the outer subgrade of the road surface, and a rockfall bench needs to be set for slopes of a certain height.

[0033] The width of the rockfall bench depends on the height and soil quality of the slope, and the width is 1 m to 2 m.

[0034] A construction method for a curved geogrid ecological slope protection structure includes the following steps:

[0035] Step 1. Determine the dimensions of the curved geogrid ecological slope protection structure

[0036] According to the cross-sectional dimensions of the subgrade and the geological conditions, preliminarily determine the dimensions of the curved geogrid ecological slope protection structure;

[0037] Through tests, determine the material performance indexes of the lower geogrid and the curved geogrid, the performance indexes of the planting soil, and select ground cover plants;

[0038] ③ Calculate and review the tension of the curved geogrid by Formula 1 and Formula 2, and determine the engineering materials and technical indexes;

[0039] Step 2. Excavate the subgrade

[0040] According to the design drawings, measure and set out the lines to determine the slope excavation plan;

[0041] ② Mechanical equipment enters the site to excavate the slope, and the excavated soil is transported to the storage yard for stacking and standby;

[0042] ③ The slope is trimmed and leveled, and the quality meets the design requirements;

[0043] Step 3. Construction of anchor rods and lattice girders

[0044] Measure and set out the positions of the anchor bolts, and transport the qualified materials to the site;

[0045] ②The anchoring construction drill rig arrives at the site, drills the anchor bolt holes, and inspects that the drilling quality meets the design requirements;

[0046] ③Slowly lower the anchor bolt into the hole and fix it in the deep layer of the slope by grouting;

[0047] ④Clean the slope surface at the side of the drilling hole and the place where the anchor bolt is lowered, and measure and set out the positions of the lattice beams;

[0048] ⑤Erect and fix the lattice beam formwork, set plastic circular sleeves at the part of the anchor bolt head exposed in the lattice beam, and reserve the expansion space for the anchor bolt anchoring;

[0049] Place and tie the steel bars in the lattice beam formwork, and inspect that the quality meets the design requirements;

[0050] Pump the cement mixture into the lattice beam formwork and vibrate it until it is dense, remove the formwork within the specified time and cure it until it is qualified;

[0051] Clean the cement concrete residues at the anchor bolt anchoring place. If it is a prestressed anchor bolt, it is necessary to tension the prestress, anchor the anchor bolt, and seal the anchor bolt anchoring end with cement concrete;

[0052] Step Four: Mix the planting soil and vegetation seeds proportionally

[0053] The plant configuration is mainly local native species with good soil and water conservation functions, combining deep-rooted plants with shallow-rooted plants. The selected plants should have the characteristics of drought resistance, barren tolerance, pollution prevention, pest and disease resistance, and being suitable for natural growth;

[0054] ②Proportion the planting soil mixture, and the soil, compound fertilizer, organic fertilizer, stabilizer, and natural fiber meet the design requirements; Select viscous red soil and yellow soil, and stones, gravels, and weeds should be removed during use. It is required that the soil particle size should not be less than 2 cm, and the water content should not be less than 30%. Soil disinfection is advisable before use;

[0055] ③Mix the planting soil mixture and water in a certain proportion and stir to form a uniform base material mixed slurry;

[0056] ④According to a certain proportioning scheme, mix the ground cover plant seeds and the base material evenly to form a uniform base material mixed slurry and a seed mixed slurry;

[0057] Step Five: Construction of the geogrid, curved geogrid, planting soil, and geotextile

[0058] Clean the slope surface to make it flat, conduct survey and lofting, and determine the positions of the lower geogrid, curved geogrid and anchor nails:

[0059] ② Lay the lower geogrid horizontally from top to bottom within a square lattice beam range, and the lap joints shall meet relevant standards;

[0060] ③ Tighten the lower geogrid from top to bottom and drive in anchor nails for fixation;

[0061] ④ Use a hydroseeder to spray the evenly mixed planting soil base material mixed slurry on the slope surface, and spray it in one or multiple times in sequence from top to bottom; the thickness of the planting soil base material mixture is divided into upper and lower layers according to the layout of the curved geogrid, and the spraying thickness of the lower layer conforms to the shape of the curved geogrid;

[0062] ⑤ After the lower layer of planting soil base material mixed slurry solidifies, lay the single - width curved geogrid from top to bottom on the solidified base material mixed slurry of the lower layer. First, fix the upper end of the curved geogrid to the side of the lattice beam with anchor nails, and then fix the curved geogrid to the solidified base material mixed slurry of the lower layer from top to bottom with anchor nails at the designed spacing, and then fix the lower end of the curved geogrid to the side of the lattice beam with anchor nails; lay the second longitudinal geogrid of the slope in parallel in this order, and the lap joints shall meet relevant standards;

[0063] Spray the upper layer of planting soil base material mixed slurry, complete the spraying of the base material and seed mixed slurry within 3 days, and the total thickness after the two - layer mixed slurry solidifies meets the design requirements;

[0064] Cover with non - woven geotextile, fix the geotextile to the planting soil base material with anchor nails, and water 1 - 2 times a day according to the soil water loss situation within three months after spraying, or install a drip irrigation system to ensure seed germination and seedling growth;

[0065] ⑧ After the construction is completed, maintain the vegetation, and repair or treat and evaluate the appearance quality and local defects, and submit for acceptance.

[0066] Compared with the prior art, the present invention mainly provides a curved geogrid ecological slope protection structure and a construction method. The ecological slope protection structure includes a road surface, and a slope provided on the inner subgrade of the road surface or the outer subgrade of the road surface. A plurality of rectangular lattice beams anchored by anchor bolts are arranged on the slope surface, and in each lattice beam, a lower geogrid, planting soil with an inner curved geogrid, and an outer sealed geotextile are sequentially laid from the inside to the outside on the slope surface. The lower geogrid and the curved geogrid are fixed on the slope by a plurality of anchor nails, and plant seeds required for forming vegetation are added to the surface layer of the planting soil. And this slope protection structure combined with the construction method has the following advantages: First, the selected lower geogrid and curved geogrid are both high-strength materials that are green, energy-saving and environmentally friendly. Compared with traditional metal mesh materials, they have the characteristics of high strength, small deformation, corrosion resistance, anti-aging, large friction coefficient, long service life, etc., and are convenient for construction, with a high cost performance; Second, the friction and bonding ability of the curved geogrid is greater than that of the straight lower geogrid, and the ecological functions of self-supporting, self-organizing and self-repairing are stronger, especially more beneficial for the initial stage when the root systems of slope vegetation have not yet grown and developed, effectively increasing the safety performance of the slope structure and reducing potential hazards of road traffic accidents; Third, the provided design calculation method has clear principles, is scientific, reasonable, practical and easy to implement, can better guide the design and construction of the curved geogrid ecological slope protection structure, and improves the safety performance. Therefore, the present invention has the advantages of simple structure, economic savings, ecological environmental protection, safety and reliability in use, can better reflect the concept of green engineering construction, and combined with the corresponding construction method, it also has high economic benefits, energy-saving and environmental protection benefits and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 is a schematic elevation view of the structure of the present invention.

[0068] Figure 2 is a cross-sectional view of the slope.

[0069] Figure 3 is Figure 2 the force diagram of the curved geogrid of DETAILED DESCRIPTION OF THE EMBODIMENTS

[0070] The embodiments of the present invention will be further described in detail below with reference to the above drawings.

[0071] As Figures 1 to 3 shown, 1. Road surface, 2. Slope, 21. Spillway, 3. Lattice beam, 31. Anchor bolt, 41. Lower geogrid, 42. Curved geogrid, 43. Geotextile, 44. Planting soil, 45. Anchor nail, 46. Vegetation.

[0072] A curved geogrid ecological slope protection structure and construction method, mainly related to the field of ecological road construction. The curved geogrid ecological slope protection structure includes a road surface 1 and a slope 2 on the inner or outer subgrade of the road surface. On the slope surface of the slope, a plurality of rectangular grid beams 3 are anchored by anchor bolts 31. Usually, a plurality of rectangular grid beams 3 can jointly enclose a square area, and in each grid beam 3 within the square area, there is a lower geogrid 41, planting soil 44 with an inner curved geogrid 42, and an outer sealed geotextile 43 laid on the slope surface from the inside out in sequence; moreover, the lower geogrid 41 and the curved geogrid 42 are fixed on the slope 2 by a plurality of anchor nails 45, and plant seeds required for forming vegetation 46 are added to the surface layer of the planting soil 44.

[0073] The road surface 1 is the road surface layer, and there is a slope 2 that needs ecological protection at a specified distance outside the inner or outer subgrade of the road surface.

[0074] The slope 2 is a slope surface formed by filling or excavation of the inner or outer subgrade of the road surface 1. A certain height of the slope 2 needs to be provided with a catchment bench 21. The catchment bench is a horizontal platform with a certain width set between the toe of the cutting slope and the outer edge of the side ditch or on the slope to prevent falling debris from falling into the side ditch. The width of the catchment bench 21 can be determined according to the slope height and soil quality, and the width is 1m - 2m. The catchment bench 21 can also be used as a passage and working area for operators during construction and maintenance.

[0075] The grid beam 3 is a reinforced concrete structure. The grid beam 3 needs to be anchored deep into the slope by anchor bolts 31 at certain intervals to play a role in stabilizing the slope 2; the anchor bolt 31 is a metal rod driven deep into the slope, which together with the grid beam 3 stabilizes the overall slope. The type and length of the anchor bolt 31 are determined by analyzing and calculating the slope soil quality, type, and height.

[0076] The lower geogrid 41 is a steel-plastic geogrid laid on the slope surface. The steel-plastic geogrid is a composite high-strength tensile strip formed by special treatment of high-strength steel wires and polyethylene (PE) or polypropylene (PP) added with other additives through extrusion, and has a rough embossed surface, and is formed into a mesh geosynthetic material by ultrasonic welding technology. Moreover, the steel-plastic geogrid is also a high-strength new building material. Compared with metal mesh materials, it has the characteristics of high strength, small deformation, corrosion resistance, anti-aging, large friction coefficient, long service life, etc., and the construction is more convenient.

[0077] The described curved geogrid 42 is arranged in a curved shape in the planting soil 44. Compared with the straight lower geogrid 41, the curved shape can better enhance the frictional resistance and bonding performance with the planting soil 44, and the curved geogrid 42 is a cosine curve. It can also be a parabola or other curves that meet the boundary conditions.

[0078] The described lower geogrid 41 and curved geogrid 42 can also be made of a rust-proof metal wire mesh or other non-metal wire meshes.

[0079] The described geotextile 43 is a needle-punched non-woven geotextile material made of polyester staple fibers, which has the functions of blocking, filtering, ventilating, draining and protecting the planting soil 44, and is beneficial to the germination and growth of plant seeds in the planting soil 44.

[0080] The described planting soil 44 is a soil mixture of soil spraying or aggregate spraying organic soil mixed with plant seeds, and the plant seeds are ground cover plant seeds adapted to the local environmental climate.

[0081] The described anchor bolts 45 are made of steel, made of round steel bars with a diameter of 8 mm to 10 mm into a shape of "7", with a length of 2 m to 5 m and equipped with auxiliary binding wires for fixing the lower geogrid and the curved geogrid, and multiple anchor bolts are arranged in a plum blossom shape.

[0082] The described vegetation 46 is the sum of ground cover plants with a certain density covering the slope surface of the slope. The vegetation 46 is adapted to the local environmental climate, and not only assists in protecting the safety of the slope structure, but also protects the ecological environment and reflects the function of landscape beautification.

[0083] The oblique length of the described curved geogrid 42 from the upper border to the lower border of the lattice beam is in the range of a cosine function curve and is arranged on the slope surface of the slope; the curved geogrid 42 is sandwiched in the described planting soil 44, and the thickness and specific gravity of the planting soil are respectively , , the frictional resistance and bonding coefficients between the planting soil 44 and the top and bottom surfaces of the curved geogrid 42 are , the frictional resistance and bonding coefficient between the planting soil 44 and the top surface of the lower geogrid 41 are , and the following calculation formula is obtained from the principle of force balance:

[0084] Formula 1,

[0085] The relevant parameters and curve equation of the force on the curved geogrid 42 are

[0086]

[0087] Formula 2,

[0088] In the early stage when the roots of the vegetation 46 on the slope 2 have not yet grown and developed, when the planting soil 44 is in the most unfavorable condition of saturated water content, the planting soil slides along the slope surface line, and the tension acting at the fixing point of the curved geogrid 42 and the upper frame and lower frame of the frame beam is

[0089]

[0090] When only the upper and lower ends of the curved geogrid 42 are fixed to the frame beam 3 by anchor nails 45, , then

[0091]

[0092] When the curved geogrid 42 is fixed by a plurality of anchors 45, the tension of the curved geogrid 42 between two adjacent anchors 45 at the anchors 45 is calculated according to the principle of Formula 2; The curved geogrid fixed by the root anchor, the upper frame of the frame beam and the lower frame of the frame beam, Solve the system of equations The tension at the root anchor, where the tension at the fixed point of the curved geogrid 42 and the lower frame of the frame beam is equal to zero;

[0093] Formula 3:

[0094] The sum of the vertical friction and cohesion between the curved geogrid 42 and the planting soil 44 is greater than the sum of the vertical friction and cohesion between the linear lower geogrid 41 and the planting soil 44, and is calculated as follows:

[0095]

[0096] The symbols in Formula 1, Formula 2 and Formula 3 are defined as:

[0097] ——respectively the width of the planting soil 44, the curve of the curved geogrid 42 one Cycle in The length on the axis, ;

[0098] ——are the deadweight load of the planting soil 44 acting on the curved geogrid 42, Axial tangential load, Axial normal load, ;

[0099] ——respectively the friction and adhesion coefficient between the planting soil 44 and the top surface of the lower geogrid 41, and the friction and adhesion coefficient between the planting soil 44 and the top and bottom surfaces of the curved geogrid 42, It is obtained through experiments that values can be consulted from relevant materials in the preliminary design stage; since the frictional resistance and adhesive force of the double-sided surface of the top and bottom of the curved geogrid are greater than those of the straight single-sided lower geogrid, and at the same time, the maximum included angle between the frictional resistance direction of the curved geogrid 42 and the sliding direction of the planting soil is 90 0 That is, perpendicular, which can more effectively block the sliding of the planting soil. Therefore, the frictional resistance and adhesive force are comprehensively increased, that is , which is more beneficial for the initial stage when the roots of the slope vegetation have not yet grown and developed, dimensionless;

[0100] —— are respectively the included angle between the slope surface and the horizontal plane, and the included angle between any position of the curved geogrid 42 and the horizontal plane, ;

[0101] —— are respectively the number of anchor nails 45 for fixing the curved geogrid 42, and the number of cosine curve periods of the curved geogrid 42 between the upper and lower borders of the grid beam;

[0102] —— are respectively the frictional resistance and adhesive force between any position of the curved geogrid 42 and the planting soil 44, the vertical component of the frictional resistance and adhesive force between any position of the curved geogrid 42 and the planting soil 44, the frictional resistance and adhesive force between any position of the straight lower geogrid and the planting soil, and the vertical component of the frictional resistance and adhesive force between any position of the straight lower geogrid 41 and the planting soil 44, ;

[0103] —— is the ratio of the sum of the vertical components of the frictional resistance and adhesive force between the curved geogrid 42 and the planting soil 44 to the sum of the frictional resistance and adhesive force between the straight lower geogrid 41 and the planting soil 44, dimensionless;

[0104] —— are respectively the tensile force at the fixed positions of the unit-width curved geogrid 42 with the upper and lower borders of the grid beam, and the allowable tensile force of the unit-width curved geogrid 42, .

[0105] At the same time, the construction method of the ecological slope protection structure with a curved geogrid mainly includes the following steps:

[0106] Step 1. Determine the dimensions of the ecological slope protection structure with a curved geogrid

[0107] According to the subgrade cross-section dimensions and geological conditions, initially determine the dimensions of the curved geogrid ecological slope protection structure;

[0108] Through tests, determine the material performance indicators of the lower geogrid 41 and the curved geogrid 42, the performance indicators of the planting soil 44, and select ground cover plants;

[0109] ③ Calculate and review the tensile force of the curved geogrid by Formula 1 and Formula 2, and determine the engineering materials and technical indicators;

[0110] Step 2: Excavate the subgrade

[0111] According to the design drawings, measure and set out the positions, and determine the excavation slope 2 plan;

[0112] ② Enter the mechanical equipment to excavate the slope, and transport the excavated soil to the storage yard for stacking and standby;

[0113] ③ Trim and level the slope 2 so that the quality meets the design requirements;

[0114] Step 3: Construct the anchor bolts and lattice girders

[0115] Measure and set out the positions of the anchor bolts 31, and transport the qualified materials to the site;

[0116] ② Place the anchoring construction drill in place, drill the anchor bolt holes, and check that the drilling quality meets the design requirements;

[0117] ③ Slowly lower the anchor bolt 31 into the hole, and grout it to fix it deep in the slope;

[0118] ④ Clean the slope surface at the drilling and the place where the anchor bolt is lowered, and measure and set out the positions of the lattice girders;

[0119] ⑤ Erect and fix the lattice girder formwork, set a plastic circular sleeve at the part of the anchor head of the anchor bolt exposed in the lattice girder, and reserve the expansion space for the anchor bolt anchoring;

[0120] Place and tie the steel bars in the lattice girder formwork, and check that the quality meets the design requirements;

[0121] Pump the cement mixture into the lattice girder formwork and vibrate it until it is dense, remove the formwork within the specified time and cure it until it is qualified;

[0122] Clean the cement concrete residues at the anchoring part of the anchor bolt 31. If it is a prestressed anchor bolt, it is necessary to tension the prestress, anchor the anchor bolt, and seal the anchor end of the anchor bolt with cement concrete;

[0123] Step 4: Mix the planting soil and vegetation seeds proportionally

[0124] The plant configuration mainly consists of local native species with good soil and water conservation functions, combining deep-rooted plants with shallow-rooted plants. The selected plants should have the characteristics of drought resistance, barren tolerance, pollution prevention, pest and disease resistance, and being suitable for natural growth;

[0125] ② Mix the planting soil mixture, and the soil, compound fertilizer, organic fertilizer, stabilizer, and natural fiber meet the design requirements; Viscous red soil or yellow soil can be selected. When using, stones, gravels, weeds, etc. should be removed. It is required that the soil particle size should not be less than 2 cm and the water content should not be less than 30%. Soil disinfection is preferably carried out before use;

[0126] ③ Mix and stir the planting soil mixture and water in a certain proportion to form a uniform base material mixed slurry;

[0127] ④ According to a certain proportioning scheme, mix the ground cover plant seeds evenly with the base material to form a uniform base material mixed slurry and seed mixed slurry;

[0128] Step Five: Construction of the lower geogrid, curved geogrid, planting soil, and geotextile

[0129] Clean and level the slope surface, measure and set out the positions of the lower geogrid 41, curved geogrid 42, and anchor bolts 45:

[0130] ② Lay the flat lower geogrid 41 from top to bottom within the range of a square grid beam 3, and the lap joints meet the relevant standards;

[0131] ③ Tighten the lower geogrid 41 from top to bottom and drive in the anchor bolts 45 for fixation;

[0132] ④ Use a hydroseeding machine to spray the evenly mixed planting soil base material mixed slurry on the slope surface, spraying in sequence from top to bottom in one or multiple times; The thickness of the planting soil base material mixture is divided into upper and lower layers according to the layout of the curved geogrid 42, and the spraying thickness of the lower layer conforms to the shape of the curved geogrid 42;

[0133] ⑤ After the lower-layer planting soil base material mixed slurry solidifies, lay the single-width curved geogrid from top to bottom on the solidified base material mixed slurry of the lower layer. First, fix the upper end of the curved geogrid to the side of the grid beam with anchor bolts, and then fix the curved geogrid to the solidified base material mixed slurry of the lower layer from top to bottom with anchor bolts at the designed spacing. Then, fix the lower end of the curved geogrid to the side of the grid beam with anchor bolts; Lay the second longitudinal geogrid on the slope in parallel in this order, and the lap joints meet the relevant standards;

[0134] Spray the upper-layer planting soil base material mixed slurry, and complete the spraying of the base material and seed mixed slurry within 3 days. The total thickness after the two layers of mixed slurry solidify meets the design requirements;

[0135] Cover the non-woven geotextile 43, which is fixed on the planting soil substrate with anchor nails 45. Water once or twice a day according to the water loss of the soil within three months after spraying, or install a drip irrigation system to ensure seed germination and seedling growth;

[0136] ⑧ After the construction is completed, the vegetation 46 shall be maintained, and the appearance quality and local defects shall be repaired or treated and evaluated, and then submitted for acceptance.

[0137] The embodiments described in the present invention are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

Claims

1. A curved geogrid ecological slope protection structure, including a road surface (1), and a slope (2) located on the inner subgrade of the road surface or the outer subgrade of the road surface. Multiple rectangular grid beams (3) anchored by anchor bolts (31) are arranged on the slope surface. It is characterized in that In each of the grid beams (3), a lower geogrid (41), planting soil (44) with a curved geogrid (42) sandwiched therein, and an outer geotextile (43) laid on the slope surface of the slope from the inside to the outside are provided; the lower geogrid (41) and the curved geogrid (42) are fixed to the slope (2) by a plurality of anchor nails (45); plant seeds required for forming vegetation (46) are incorporated into the surface layer of the planting soil (44); the oblique length of the curved geogrid (42) from the upper border to the lower border of the grid beam is in the form of a cosine function curve and is arranged on the slope surface of the slope; the planting soil (44) sandwiches the curved geogrid (42), and the thickness and unit weight of the planting soil are and respectively, and the friction and adhesion coefficients between the planting soil (44) and the top and bottom surfaces of the curved geogrid (42) are , and the friction and adhesion coefficients between the planting soil (44) and the top surface of the lower geogrid (41) are . The following calculation formula is obtained based on the principle of force balance: Formula 1 The relevant parameters and curve equation of the curved geogrid (42) under force are Formula 2 In the initial stage when the root systems of the vegetation (46) on the slope (2) have not yet grown and developed, when the planting soil (44) is in the most unfavorable situation of saturated water content, the planting soil slides downward along the slope surface line, and the tensile force acting at the fixed points of the curved geogrid (42) with the upper border and the lower border of the grid beam is When only the upper and lower ends of the curved geogrid (42) are fixed to the lattice girder (3) with anchor bolts (45), , then there is When the curved geogrid (42) is fixed by a plurality of anchors (45), the tension of the curved geogrid (42) between two adjacent anchors (45) at the anchors (45) is calculated according to the principle of Formula 2; The curved geogrid fixed by the root anchor, the upper frame of the frame beam and the lower frame of the frame beam, Solve the system of equations The tension at the root anchor, wherein the tension at the fixing point of the curved geogrid (42) and the lower frame of the frame beam is equal to zero; Formula 3 The total vertical frictional resistance and adhesive force between the curved geogrid (42) and the planting soil (44) are larger than the total vertical frictional resistance and adhesive force between the straight lower geogrid (41) and the planting soil (44). The calculation is as follows: The definitions of each symbol in Formula 1, Formula 2 and Formula 3 are: —— namely, the thickness of the planting soil (44) and the length of the curve of the curved geogrid (42) on the curve One Period within Length on the axis, ; —— the self-weight load of the planting soil (44) acting on the curved geogrid (42), the axial tangential load, the normal load in the axial direction, ; —— the friction and adhesion coefficients between the planting soil (44) and the top surface of the lower geogrid (41), and the friction and adhesion coefficients between the planting soil (44) and the top and bottom surfaces of the curved geogrid (42), obtained through tests, , dimensionless; —— the angle between the slope surface and the horizontal plane, and the angle between any point on the curved geogrid (42) and the horizontal plane, respectively; ; —— the number of anchor nails (45) for fixing the curvilinear geogrid (42) and the number of cosine curve periods of the curvilinear geogrid (42) between the upper frame beam and the lower frame beam respectively; —— the frictional resistance and adhesive force between any point of the curved geogrid (42) and the planting soil (44), the vertical component of the frictional resistance and adhesive force between any point of the curved geogrid (42) and the planting soil (44), the frictional resistance and adhesive force between any point of the straight lower geogrid and the planting soil, the vertical component of the frictional resistance and adhesive force between any point of the straight lower geogrid (41) and the planting soil (44), ; ; ; ; ; —— The ratio of the sum of the vertical components of the frictional resistance and adhesive force between the curved geogrid (42) and the planting soil (44) to the sum of the frictional resistance and adhesive force between the straight lower geogrid (41) and the planting soil (44), dimensionless; —— are the tensile forces at the fixed positions of the unit-width curved geogrid (42) with the upper and lower borders of the lattice beam, and the allowable tensile force of the unit-width curved geogrid (42), .

2. A curved geogrid ecological slope protection structure according to claim 1, It is characterized in that The described curved geogrid (42) is arranged in a curved shape in the planting soil (44), and the curved geogrid (42) is a cosine curve. Or a parabola or other curves that satisfy the boundary conditions.

3. A curved geogrid ecological slope protection structure according to claim 1, It is characterized in that The lower geogrid (41) and the curved geogrid (42) are steel-plastic geogrids or rust-proof treated metal wire meshes or non-metal wire meshes laid on the slope surface.

4. A curved geogrid ecological slope protection structure according to claim 1, It is characterized in that Multiple anchor nails (45) are made of steel. Each anchor nail (45) is made of round steel with a diameter of 8 mm to 10 mm into a 7-shaped shape, with a length of 2 m to 5 m, and is equipped with auxiliary binding wires to fix the lower geogrid (41) and the curved geogrid (42), and multiple anchor nails (45) are arranged in a plum blossom shape.

5. A curved geogrid ecological slope protection structure according to claim 1, It is characterized in that The geotextile (43) is a needle-punched non-woven geotextile material made of polyester staple fiber; the planting soil (44) is a soil mixture of imported soil spray seeding or aggregate spray seeding with plant seeds added.

6. A curved geogrid ecological slope protection structure according to claim 1, It is characterized in that The road surface (1) is a road surface layer; the slope (2) is formed by filling or excavation of the inner subgrade or the outer subgrade of the road surface, and a catchment bench (21) needs to be set for a slope (2) of a certain height.

7. A curved geogrid ecological slope protection structure according to claim 6, It is characterized in that The width of the catchment bench (21) depends on the height and soil quality of the slope (2), and the width is 1 m to 2 m.

8. A construction method of a curved geogrid ecological slope protection structure according to any one of claims 1 to 7, It is characterized in that This construction method includes the following steps: Step 1. Determine the dimensions of the curved geogrid ecological slope protection structure ① According to the cross-sectional dimensions of the subgrade and the geological conditions, initially determine the dimensions of the curved geogrid ecological slope protection structure; ②Determine the material property indexes of the lower geogrid (41) and the curved geogrid (42), and the property indexes of the planting soil (44) through tests, and select ground cover plants; ③Calculate and review the tension of the curved geogrid by Formula 1 and Formula 2, and determine the engineering materials and technical indexes; Step 2: Excavate the roadbed ①Measure and set out according to the design drawings to determine the excavation slope plan; ②Construction machinery and equipment enter the site to excavate the slope, and the excavated soil is transported to the storage yard for stacking and standby; ③The slope (2) is trimmed and leveled, and the quality meets the design requirements; Step 3: Construction of anchor bolts and lattice girders ①Measure and set out the positions of the anchor bolts (31), and the materials used are inspected and qualified and transported to the site; ②The anchoring construction drill rig arrives at the site, drills the anchor bolt holes, and the inspection of the drilling quality meets the design requirements; ③Slowly lower the anchor bolt into the hole and fix it in the deep layer of the slope by grouting; ④Clean the slope surface at the slope drilling and anchor bolt lowering positions, and measure and set out the positions of the lattice girders; ⑤Erect and fix the lattice girder formwork, and set plastic circular sleeves at the anchor bolt heads exposed in the lattice girders to reserve the expansion space for anchor bolt anchoring; ⑥Place and tie the steel bars in the lattice girder formwork, and the inspection of the quality meets the design requirements; ⑦Pump the cement mixture into the lattice girder formwork and vibrate it until it is dense, and remove the formwork within the specified time and cure it qualified; ⑧Clean the cement concrete residues at the anchor bolt anchoring points. If it is a prestressed anchor bolt, the prestress needs to be tensioned, the anchor bolt is anchored, and the anchor bolt anchoring end is sealed with cement concrete; Step 4: Mix the planting soil and vegetation seeds proportionally ①The plant configuration is mainly based on local native species with good soil and water conservation functions, combining deep-rooted plants with shallow-rooted plants. The selected plants should have the characteristics of drought resistance, barren tolerance, pollution prevention, pest and disease resistance, and being suitable for natural growth; ②Mix the planting soil mixture proportionally, and the soil, compound fertilizer, organic fertilizer, stabilizer, and natural fiber meet the design requirements; select viscous red soil and yellow soil, and stones, gravels, and weeds should be removed during use. Soil disinfection should be carried out before use; ③Mix the planting soil mixture and water in a certain proportion and stir to form a uniform base material mixed slurry; ④According to a certain proportioning scheme, mix the ground cover plant seeds evenly with the base material to form a uniform base material mixed slurry and a seed mixed slurry; Step 5: Construction of the lower geogrid, curved geogrid, planting soil, and geotextile ①Clean and level the slope surface, measure and set out to determine the positions of the lower geogrid (41), the curved geogrid (42), and the anchor nails (45); ②Lay the lower geogrid (41) horizontally from top to bottom within the range of a square lattice girder (3), and the lap joints meet the relevant standards; ③Tighten the lower geogrid (41) from top to bottom and drive in the anchor nails (45) for fixation; ④Use a spraying machine to spray the evenly mixed planting soil base material mixed slurry on the slope surface, and spray it in order from top to bottom in one or multiple times; the thickness of the planting soil base material mixture is divided into upper and lower layers according to the layout of the curved geogrid, and the spraying thickness of the lower layer conforms to the shape of the curved geogrid; ⑤After the lower-layer planting soil base material mixture slurry has solidified, the single-curve geogrid is laid from top to bottom on the solidified lower-layer base material mixture slurry. First, fix the upper end of the curve geogrid to the side surface of the lattice beam with anchor nails, and then fix the curve geogrid to the solidified lower-layer base material mixture slurry from top to bottom and fix it with anchor nails at the designed spacing. Then, fix the lower end of the curve geogrid to the side surface of the lattice beam with anchor nails; lay the second longitudinal geogrid on the slope in parallel in this order, and the lap joint complies with relevant standards; ⑥Spray the upper-layer planting soil base material mixture slurry, and complete the spraying of the base material and seed mixture slurry within 3 days. The total thickness after the two-layer mixture slurry has solidified meets the design requirements; ⑦Cover with non-woven geotextile (43), fix the geotextile to the planting soil base material with anchor nails, and water 1 to 2 times a day according to the water loss of the soil within three months after spraying, or install a drip irrigation system to ensure seed germination and seedling growth; ⑧After the construction is completed, maintain the vegetation, repair or treat and evaluate the appearance quality and local defects, and submit for acceptance.

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