An ecological half-cut and half-filled roadbed structure and construction method for mountain highway

Abstract

The invention discloses an ecological half-cut and half-filled roadbed structure and construction method for a mountain highway, comprising the steps of sequentially excavating an excavation line on a ground line with a natural slope of the mountain, excavating a half-cut and half-filled joint into multiple steps, and building a retaining wall on the shoulder part, mainly paving multiple layers of geocells on the multiple steps, pouring a semi-fluid binder in the multiple layers of geocells to form a composite body, filling the space between the composite body and the retaining wall, and sequentially paving a road base and a road surface on the composite body and the fill in the retaining wall, thereby forming a geocell-reinforced, vehicle-passable half-cut and half-filled roadbed and road surface stable structure; multiple drainage pipes are buried in the composite body, the fill and the retaining wall, and each drainage pipe extends out of the retaining wall to discharge seepage water; therefore, the invention has the structural advantages of simple structure, economic applicability, ecological environmental protection, energy saving and emission reduction, embodies the concept of green engineering construction, and has high economic and social benefits when combined with corresponding construction methods.

Description

Technical Field

[0001] The invention relates to the field of ecological road construction, and in particular to an ecological half-cut and half-filled roadbed structure and a construction method for a mountain highway. Background Art

[0002] The mountainous area of ​​my country accounts for about two-thirds of the country's land area. In the economic construction and development of mountainous areas, roads are one of the main infrastructures that are prioritized for construction. Roads are strip projects. Based on the requirements of mountain slopes and ecological environment, the natural surface excavation and filling area is reduced as much as possible, and the excavated materials are fully utilized to save scarce mountain resources. The road adopts a half-cut and half-filled form. One part of this roadbed is a natural roadbed, and the other part is a newly filled fill. There is an intersection between the two parts. Since the excavation part destroys the geological structure of the original mountain, the new fill increases the load of the mountain and the newly filled roadbed, which is prone to sliding damage; at the same time, the material properties of the fill are different from those of the mountain, which can easily lead to uneven longitudinal and transverse settlement and cracking of the half-cut and half-filled roadbed. Therefore, there are many diseases that occur in the half-cut and half-filled roadbed during the construction process and the operation stage, which is an issue that needs to be focused on in the stability design and analysis methods.

[0003] The existing half-cut and half-filled roadbed adopts a variety of measures at the intersection of cut and fill to prevent uneven settlement of the roadbed and sliding deformation of the newly filled roadbed. When the slope is high and steep or the stability is poor and it is not suitable to dig more, bridges, suspended platforms and other structures can be used; when the integrity of the mountain rock is good, half-mountain caves can be used; for the half-cut and half-filled roadbed on the general steep slope, according to the terrain and geological conditions, shoulders, stone masonry or retaining walls can be used, steps can be excavated in the roadbed range of the intersection of cut and fill and geogrids can be laid. Although the above measures can improve the performance of the half-cut and half-filled roadbed to a certain extent, the use of bridges, suspended platforms, half-mountain caves and other structures in the half-cut and half-filled section leads to excessively high costs, and the tensile force of laying geogrids is not effective, and the application benefits are poor.

[0004] The newly filled roadbed during widening of ordinary roads also falls into the category of half-cut and half-fill roadbed. There are also application examples of using geocells to reinforce the newly filled roadbed. However, the density of the fill material in the geocell is difficult to control and the geocell is easily damaged during rolling. Therefore, geocells are not widely used to reinforce half-cut and half-fill roadbed.

[0005] Geocell is a three-dimensional mesh cell structure formed by high-strength welding of reinforced HDPE sheet materials. It is a high-strength geotechnical building material with green ecology, energy saving and emission reduction. In order to make full use of the high strength and aggregation characteristics of geocell, starting from filling loose materials in the traditional geocell is a direction of geocell application research, which is conducive to broadening the application scope of geocell and further promoting the construction of ecological roads with semi-cut and semi-filled roadbeds. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide an ecological half-cut and half-filled roadbed structure and construction method for mountain highways which are simple in structure, economical and applicable, environmentally friendly, and energy-saving and emission-reducing.

[0007] The technical problem of the present invention is achieved through the following technical solutions:

[0008] An ecological half-cut and half-filled roadbed structure for a mountain highway comprises: excavating an excavation line in sequence on the ground line of the natural slope of the mountain, excavating a half-cut and half-filled joint into multiple steps, and building a retaining wall on the shoulder portion; laying multiple layers of geocells on the multiple steps; pouring a semi-fluid binder in the multiple layers of geocells to form a composite of the geocells and the binder; building fill between the composite and the retaining wall; laying a road base and a pavement in sequence on the composite and the fill in the retaining wall, and forming a geocell-reinforced ecological half-cut and half-filled roadbed pavement stable structure for vehicle traffic; and burying multiple drainage pipes in the composite, fill and retaining wall, each of which extends out of the retaining wall to discharge seepage water.

[0009] The multi-layer geocell is paved from bottom to top on the multiple steps of the excavation line. The multi-layer geocell extends a certain length in the direction of the retaining wall and extends longitudinally along the half-cut and half-filled roadbed structure. The composite of the geocell and the binder and the multiple steps of the excavation line form an overall oblique composite from bottom to top and from horizontal to vertical. The cross section of the composite is generally a trapezoid with unequal thickness at the upper and lower ends, and the oblique length of the center line of the trapezoid is , the angle with the horizontal line is , the horizontal thickness of the lower end is , the horizontal thickness of the upper end is , the angle of the variable section is , starting from the center line of the lower end of the trapezoid To the midpoint of the upper centerline for axis; assuming that the longitudinal length of the composite along the half-cut and half-filled roadbed structure is much greater than the oblique length , so take the longitudinal length As the width of the complex of the inclined trapezoid, the complex is regarded as a one-dimensional variable thickness elastic foundation beam. The two ends of the elastic foundation beam are elastically hinged. According to the Winkler assumption, the foundation reaction force of the elastic foundation beam is , the equivalent vertical load strength of the vehicle weight is ; The following calculation formula is obtained from Coulomb's earth pressure theory, elastic mechanics and the principle of force balance:

[0010] Formula 1:

[0011] Under the action of vehicle load and active earth pressure of road surface, base and fill, the retaining wall produces a small displacement outward. Assuming that the rupture surface is the upper edge top surface of the trapezoidal cross section of the composite body, that is, rupture surface II, taking non-cohesive fill as an example, the component force distribution load acting on the composite body is

[0012]

[0013] Where, the Coulomb active earth pressure coefficient and the angle with the horizontal line are

[0014]

[0015] Because there is friction and The load component in the axial direction produces shear deformation. Any axis direction The axial load strength at

[0016]

[0017] Perpendicular to Any axis direction The load intensity at

[0018]

[0019] To simplify the calculation, it is assumed that the frictional resistance of the complex The load component in the axial direction is The axial flexural deformation is irrelevant. The microelement analysis of the complex is performed. The moment of the center of the right side of the microelement is taken. ,have

[0020] Neglecting the second-order trace, we get

[0021]

[0022] Depend on The resultant force in the axial direction is equal to Available

[0023]

[0024] The relationship between the bending moment and deflection of the elastic foundation beam

[0025]

[0026] From the above equations, the differential equation of the elastic foundation beam is:

[0027] In the formula

[0028]

[0029] Formula 2:

[0030] The differential equation in formula 1 is a variable coefficient ordinary differential equation, which can be solved by power series, but the solution process is very complicated. Now we use the fifth power series to fit. Let ,have to

[0031]

[0032] Here we assume that the two ends of the elastic foundation beam , It also conforms to the Winkler assumption that the two end points , The displacement is caused by the shear force The boundary conditions and load conditions give

[0033] The fifth power series coefficient and the two ends of the elastic foundation beam are obtained from the boundary conditions , of for

[0034]

[0035] Substitution Can be found and

[0036] Substituting the above five coefficients into Formula 2, we get the solution of elastic foundation beam fitting;

[0037] In formula 2, when the variable cross-section rate of the elastic foundation beam is Or smaller, take Simplify the calculation of uniform cross-section beams, or simplify the variable cross-section of elastic foundation beams into stepped beams. Segment calculation, each segment takes For equal cross-sections, a differential equation group is listed for calculation according to the continuity conditions, but the number of segments should not be too many to avoid increasing the amount of calculation work;

[0038] Formula 3:

[0039] In order to obtain the maximum bending moment of the elastic foundation beam, let ,Right now

[0040]

[0041] If we can find the interval in the above equation Real roots in , we can get the maximum and maximum values ​​of the bending moment of the elastic foundation beam, and analyze whether the maximum value is reasonable in combination with the actual problem, discard the unreasonable maximum value, and then press Value application;

[0042] Similarly, in order to obtain the maximum shear force of the elastic foundation beam, let ,Right now

[0043]

[0044] If we can find the interval in the above equation Real roots in , we can get the maximum and maximum values ​​of the shear force of the elastic foundation beam, and analyze whether the maximum value is reasonable in combination with the actual problem, discard the unreasonable maximum value, and then press

[0045]

[0046] Value application;

[0047] Formula 4:

[0048]

[0049] The symbols in Formula 1, Formula 2, Formula 3 and Formula 4 are defined as:

[0050] ——respectively the width of the elastic foundation beam, the horizontal thickness of the upper end of the elastic foundation beam, the horizontal thickness of the lower end of the elastic foundation beam, and the thickness of any part of the elastic foundation beam. The cross-sectional height, the diagonal length of the elastic foundation beam, the width of the vehicle load, the length of the vehicle load, ;

[0051] ——respectively the height of the retaining wall, i.e. the vertical height from the lower end to the upper end of the elastic foundation beam, the thickness of the base layer, and the thickness of the road surface. ;

[0052] ——respectively are vehicle weight and equivalent fill vertical load strength of vehicle, ;

[0053] ——When vehicle load and active earth pressure of pavement, base and fill act on any part of the composite The component distributed load at ;

[0054] ——When vehicle load and active earth pressure of pavement, base and fill act on any part of the center line of the composite The axial distributed load at ;

[0055] ——When vehicle load and active earth pressure of pavement, base and fill act on any part of the center line of the composite The vertical distributed load at ;

[0056] —— foundation reaction force of elastic foundation beam, ;

[0057] ——coefficient of foundation reaction of elastic foundation beam, Obtained from reference materials or actual measurements, dimensionless, ;

[0058] ——The total pressure of the sum of vehicle load and structural load on the top of the elastic foundation beam, the internal friction angle of the fill, and the friction angle of the retaining wall back, ;

[0059] ——Poisson’s ratio of the elastic foundation beam composed of the composite body, Coulomb’s earth pressure coefficient of the vehicle load and the structural load above the top surface of the elastic foundation beam, dimensionless;

[0060] ——Respectively, the elastic modulus of the elastic foundation beam of the composite, the elastic modulus of the geocell, the elastic modulus of the binder, and the elastic modulus of any part of the elastic foundation beam. The moment of inertia of the cross section, the moment of inertia of the cross section at the lower end of the elastic foundation beam, the moment of inertia of the cross section at the upper end of the elastic foundation beam, the elastic modulus proportional coefficient of the geocell in the elastic foundation beam composite, and the elastic modulus proportional coefficient of the binder in the elastic foundation beam composite, where Determined by experiment, , dimensionless;

[0061] ——Deformation of elastic foundation beam caused by Friction per unit length in the direction, ;

[0062] ——Deformation of elastic foundation beam caused by Directional pull, ;

[0063] ——respectively the center origin of the lower end of the inclined elastic foundation beam of Axis, Axis vertical axis, ;

[0064] ——respectively the angle between the elastic foundation beam and the horizontal line, and the angle of the cross-section change rate of the linear variable cross-section elastic foundation beam , ;

[0065] ——Number 1, 2, 3....;

[0066] ——They are respectively the deflection curve of the elastic foundation beam under load, the deflection curve fitted by the fifth power series, and the lower end of the elastic foundation beam fitted by the fifth power series The deflection at the top of the elastic foundation beam fitted by the fifth power series The deflection at ;

[0067] ——respectively the weight of the pavement, the weight of the base layer, the weight of the fill, and the weight of the composite, ;

[0068] ——are the elastic foundation beams at any position under load The bending moment of the elastic foundation beam at any point of the fifth power series fitting The bending moment and elastic foundation beam are at the lower end of the fifth power series fitting The bending moment at the elastic foundation beam is at the upper end of the fifth power series fitting The bending moment at ;

[0069] ——are the elastic foundation beams at any position under load The shear force and elastic foundation beam are fitted at any point of the fifth power series. The shear force and elastic foundation beam are at the lower end of the fifth power series fitting The shear force and elastic foundation beam at the upper end of the fifth power series fitting The shear force at ;

[0070] ——are the unknown coefficients of the elastic foundation beam in the fifth power series fitting, .

[0071] The geocell is a three-dimensional mesh cell structure formed by high-strength welding of reinforced HDPE sheet materials. The plane size or height of a single geocell is 15cm to 25cm, and the HDPE sheet materials constituting the geocell are vertically porous.

[0072] The binder is semi-fluid geopolymer concrete, which is composed of geopolymer, cement and sandstone, and is in a fluidized state and is easy to be poured into the geocell.

[0073] The overall structure of the composite conforms to Hooke's law, and the Poisson's ratio of the lateral strain to the vertical strain is The fill is a loose structure, and its active earth pressure coefficient Greater than The complex is set to be wider at the bottom and narrower at the top, or narrower at the bottom and wider at the top, or the same size at the top and bottom according to actual conditions.

[0074] The drainage pipe is a PVC pipe, one end of which is in close contact with the outer edge of the complex, and the other end extends 10cm to 20cm outside the retaining wall. Each drainage pipe is provided with a plum blossom-shaped seepage hole and is covered with geotextile, and the drainage slope is 1% to 2%.

[0075] The rupture surface refers to the active earth pressure generated by the fill under the joint action of vehicle load, road surface and base layer, which pushes the retaining wall to slide to the outside of the roadbed or rotate around a certain point of the retaining wall foundation, and causes cracks in the fill from a certain height of the retaining wall to the road surface. The crack forms a rupture surface along the longitudinal direction of the half-cut and half-filled roadbed. A complex of geocell and binder is set on the roadbed at the junction of the half-cut and half-filled, and the rupture surface most likely to occur at the junction is moved outward, thereby reducing the earth pressure of the fill and reducing the number of retaining wall projects.

[0076] The ground line is the cross-sectional line of the mountain road route, and serves as the reference line for the longitudinal and cross-sectional design of the half-cut and half-fill roadbed structure; the excavation line is the connecting line of the part of the cross section that needs to be excavated determined according to the excavation depth in the center of the road route.

[0077] The retaining wall is a gravity retaining wall, which is constructed of block stones and reinforced concrete; the width of the steps at each level is not less than 1.0m, and the height of the steps at each level is not less than 0.3m; the backfill is made of ordinary soil, slag and gravel excavated from the slope and compacted by rolling; the base layer is cement stabilized soil and compacted by rolling; the road surface is a cement concrete road surface or an asphalt concrete road surface.

[0078] A construction method for an ecological half-cut and half-filled roadbed structure for a mountain highway comprises the following steps:

[0079] Step 1: Determine the size of the geocell and binder composite

[0080] According to the cross-sectional dimensions and geological conditions of the half-cut and half-fill roadbed structure determined in the design drawings, the composite dimensions of the geocell and the binder are initially proposed;

[0081] Determine the material performance index of geocell, the performance index of binder and the performance index of composite through experiments;

[0082] ③ Calculate and verify the structures of retaining walls, fills and composites using Formulas 1, 2, 3 and 4, and determine the engineering materials and technical indicators;

[0083] Step 2: Excavation of roadbed

[0084] Measure and stake out according to the design drawings and determine the excavation line;

[0085] ② Mechanical equipment enters the site, excavates the roadbed and retaining wall foundation from top to bottom, and transports the excavated material to the yard for storage;

[0086] ③ Excavate the steps at the junction of the half-cut and half-filled roadbed structure, and keep each step on the same horizontal plane along the longitudinal direction of the route, and the quality meets the design requirements;

[0087] Step 3: Retaining wall, fill and composite construction

[0088] Clean the retaining wall foundation and ensure that the bearing capacity meets the design requirements;

[0089] ② Taking the construction of a cement concrete retaining wall with three layers and each section of 15m to 20m in the longitudinal direction as an example, mix the cement concrete mixture, place the formwork, pad the settlement joint material between the foundations of each section of the retaining wall, pump and cast the cement concrete retaining wall foundation, lay the geotextile and sprinkle water for curing to the design requirements; clean the concrete scum on the top surface of the foundation and roughen the surface; erect the lower retaining wall formwork, pad the settlement joint material between the wall of each section of the retaining wall, pump and cast the cement concrete retaining wall body; and inspect the quality to meet the design requirements;

[0090] ③Clear the step foundation at the junction of the half-excavation and half-fill roadbed structure, and the bearing capacity meets the design requirements;

[0091] ④ The geocell is laid horizontally on the bottom step toward the retaining wall to the designed width and vertically toward the route direction. The geocell material is tightened to open each geocell and then fixed with soil nails. The geocell is laid continuously on each retaining wall. The vertical penetration rate of the holes of the geocell is not less than 70%, so as to facilitate the pouring of semi-fluid geopolymer concrete.

[0092] ⑤ Set up a fixed formwork on the outside of the geocell, close to the edge of the geocell;

[0093] Pump semi-fluid geopolymer concrete into each geocell. If it is not dense, insert a small vibrator into the geocell to vibrate. The vibrator cannot touch the HDPE sheet material of the geocell. The top surface needs to be smoothed with a trowel, and the geotextile is laid and watered to maintain it to the design requirements. The inspection quality meets the design requirements.

[0094] Backfill the soil simultaneously and compact it with small machinery;

[0095] Follow step 3④~ Simultaneously construct the geocell, binder and layered fill to the first retaining wall and level it, then follow step 3②~ The second layer of retaining wall, geocell, binder and layered fill are constructed simultaneously. Then follow step 3②~ The third layer of retaining wall, geocell, binder and layered filling are constructed simultaneously until the top surface of the road surface; when the binder is low-grade cement mortar, low-grade cement concrete or cement stabilized soil, the above method is similar;

[0096] Simultaneously check that the fill compaction meets the design requirements;

[0097] Step 4: Base and pavement construction

[0098] Measure and stake out to determine the elevation of the base layer:

[0099] ②Lay the base layer in layers and compact it;

[0100] ③Measure and stake out to determine the elevation of the road surface:

[0101] ④ The machinery and equipment are in place, and the road materials are mixed and transported to the site for paving operations;

[0102] ⑤ Roll the road mixture and conduct inspection and acceptance according to standards.

[0103] Compared with the prior art, the present invention mainly provides an ecological half-cut and half-filled roadbed structure and construction method for mountain roads. By setting a composite of geocells and binders at the junction of the half-cut and half-filled roadbed, various diseases of the half-cut and half-filled roadbed structure can be solved, ensuring the safety and quality of the project. It is the main building material for ecological road construction. The present invention has the following advantages: first, the geocell is a green, energy-saving and environmentally friendly high-strength material. The waste-utilized geopolymer saves a large amount of raw materials and energy and reduces pollution to the environment. The composite of the geocell and the binder has a small lateral deformation, which improves the stability of the semi-cut and semi-filled roadbed structure and reduces uneven settlement, and has a high cost-effectiveness ratio; second, the composite is set at the roadbed at the junction of the semi-cut and semi-filled roadbed, and the most easily generated rupture surface at the junction is moved outward, reducing the earth pressure of the fill, reducing the number of retaining wall projects, and saving economy; third, the composite is easy to construct. Compared with the geocell filled with gravel, ordinary soil, reinforced soil or other loose aggregates, the geocell filled with the binder can achieve a high degree of density without mechanical rolling, avoiding mechanical rolling damage to the geocell structure; fourth, the design and calculation method provided is clear in principle, scientific and reasonable, practical and easy to implement, and can guide the design and construction of geocell reinforcement of the semi-cut and semi-filled roadbed, thereby improving the reinforcement effect. Therefore, the present invention is a geocell reinforcement method for a semi-excavation and semi-filling roadbed with a simple structure, economic applicability, environmental protection, energy conservation and emission reduction, which embodies the concept of green engineering construction. Combined with the corresponding construction method, it has high economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0104] Figure 1 It is a schematic diagram of the structural elevation of the present invention.

[0105] Figure 2 This is the force diagram of the fill.

[0106] Figure 3 This is the force diagram of the geocell. DETAILED DESCRIPTION

[0107] The embodiments of the present invention will be described in detail below with reference to the above-mentioned drawings.

[0108] like Figure 1~Figure 3 As shown, 1. ground line, 2. excavation line, 21. steps, 3. retaining wall, 31. drainage pipe, 4. geocell, 5. binder, 6. fill, 7. base, 8. pavement, 9. fracture surface, 91. fracture surface I, 92. fracture surface II.

[0109] An ecological half-cut and half-filled roadbed structure and construction method for mountain highways, such as Figure 1As shown, it belongs to the field of ecological road construction. Its structure includes excavating an excavation line 2 in sequence on the ground line 1 of the natural slope of the mountain, excavating a multi-step step 21 at the junction of the half-excavation and half-filling, and building a retaining wall 3 on the shoulder part, laying a multi-layer geocell 4 in a certain range on the multi-step step 21, pouring a semi-fluid binder 5 in the multi-layer geocell, and forming a complex of the geocell and the binder; filling 6 is filled between the composite and the retaining wall 3, and then a road base 7 and a road surface 8 are sequentially paved on the composite and the filling 6 in the retaining wall 3, and a stable structure of an ecological half-excavation and half-filling roadbed and road surface reinforced by the geocell 4 is formed for vehicle passage; a plurality of drainage pipes 31 are buried in the composite, the filling 6 and the retaining wall 3, and each drainage pipe extends out of the retaining wall 3 to discharge seepage water, which is beneficial to the stability of the half-excavation and half-filling roadbed structure.

[0110] Among them, ground line 1 is the transverse ground profile line of the mountain road route, which serves as the reference line for the longitudinal and cross-sectional design of the half-cut and half-fill roadbed structure; excavation line 2 is the connecting line of the part of the cross section that needs to be excavated determined according to the excavation depth in the center of the road route. The excavation line needs to take into account the stability of the excavation slope and the fill retaining wall.

[0111] The steps 21 are located at the half-excavation and half-filling interface. In order to prevent the fill from sliding, the surface weathering layer is removed from the excavation ground line 1 and then excavated step by step into multiple steps. The width of each step 21 should not be less than 1.0m, and the height of each step 21 should not be less than 0.3m.

[0112] The retaining wall 3 is a gravity retaining wall, and other forms of retaining walls can also be used as a supporting structure for half-excavated and half-filled garbage fill, maintaining the overall stability and normal use of the road under the action of the road surface 8, roadbed, fill 6 and vehicle loads. The retaining wall 3 can be constructed with blocks of stone or reinforced concrete.

[0113] The drainage pipe 31 is a PVC pipe, one end of which is in close contact with the outer edge of the composite, and the other end of which extends into the retaining wall 3 and protrudes 10 cm to 20 cm outside the retaining wall surface. The drainage pipe 31 buried in the composite, fill 6 and retaining wall 3 is provided with plum blossom-shaped seepage holes and is covered with geotextile, with a drainage slope of 1% to 2%.

[0114] The geocell 4 is a three-dimensional mesh cell structure formed by high-strength welding of reinforced HDPE sheet materials. After filling with materials, it forms a structure with strong lateral restrictions and high rigidity. It is a green, ecological, energy-saving and emission-reducing high-strength geotechnical building material. The plane size or height of a single geocell 4 is 15cm to 25cm. The HDPE sheet material constituting the geocell 4 is vertically porous, which makes it easy for the binder 5 to penetrate between each geocell 4 and bond into a whole.

[0115] The binder 5 is a semi-fluid geopolymer concrete, which is made of mineral waste and construction waste as raw materials, with AlO4 and SiO4 as the main components. AlO4 and SiO4 tetrahedral structural units form an inorganic polymer with a three-dimensional network structure, with a chemical formula of Mn{-(SiO2)zAlO2}n·wH2O, amorphous to semi-crystalline, and has excellent mechanical properties and acid and alkali resistance.

[0116] Geopolymer has a stable network structure, and can avoid the alkali-aggregate reaction caused by the migration of metal ions and the reaction of aggregates in ordinary cement, so it has a strong ability to withstand natural damage and high durability. The geopolymer reaction process is a dehydration reaction between aluminum silicate, which is reversible under strong alkaline conditions; on the other hand, the raw material becomes a product, and no other substances are lost except dehydration. After being crushed, the waste geopolymer can be used directly as a raw material, saving a lot of raw materials, energy and reducing pollution to the environment. Geopolymer concrete is composed of geopolymer, cement and sand and gravel, and is in a plastic state and easy to focus on the geocell. Compared with the geocell filled with gravel, ordinary soil, reinforced soil or other aggregates, the binder 5 fills the geocell 4 without mechanical rolling to achieve a high degree of density, avoiding mechanical rolling damage to the geocell structure. The binder can also be low-grade cement mortar, low-grade cement concrete or cement stabilized soil, which not only meets the force requirements but also saves investment.

[0117] The overall structure of the composite conforms to Hooke's law, and the Poisson's ratio of the lateral strain to the vertical strain is , ordinary soil, slag and other fill 6 is a loose structure, and its active earth pressure coefficient Greater than ,because The composite of the geocell 4 and the binder 5 can reduce the static soil pressure or active soil force, which is beneficial to the safety of the half-cut and half-filled roadbed structure and the retaining wall 3. The composite of the geocell 4 and the binder 5 can be set to be wide at the bottom and narrow at the top, narrow at the bottom and wide at the top, or the same size at the top and bottom according to actual conditions.

[0118] The filling 6 is made of local materials, such as ordinary soil, slag and gravel excavated from the slope, which needs to be compacted by rolling; the base layer 7 is cement stabilized soil or other suitable base layer, which needs to be compacted by rolling; the road surface 8 is a cement concrete road surface or an asphalt concrete road surface, and the quality meets the design requirements.

[0119] The multi-layer geocell is laid from bottom to top on the multi-step steps of the excavation line. The multi-layer geocell extends a certain length in the direction of the retaining wall and extends longitudinally along the half-cut and half-filled roadbed structure. The composite of the geocell 4 and the binder 5 and the multi-step steps 21 of the excavation line 2 form an overall oblique composite from bottom to top and from the horizontal to the longitudinal direction. The cross section of the composite is generally a trapezoid with unequal thickness at the upper and lower ends, and the oblique length of the center line of the trapezoid is , the angle with the horizontal line is , the horizontal thickness of the lower end is , the horizontal thickness of the upper end is , the angle of the variable section is , starting from the center line of the lower end of the trapezoid To the midpoint of the upper centerline for axis; assuming that the longitudinal length of the composite along the half-cut and half-filled roadbed structure is much greater than the oblique length , so take the longitudinal length As the width of the complex of the inclined trapezoid, the complex is regarded as a one-dimensional variable thickness elastic foundation beam. The two ends of the elastic foundation beam are elastically hinged. According to the Winkler assumption, the foundation reaction force of the elastic foundation beam is , the equivalent vertical load strength of the vehicle weight is ; The following calculation formula is obtained from Coulomb's earth pressure theory, elastic mechanics and the principle of force balance:

[0120] Formula 1:

[0121] Under the action of vehicle load and active earth pressure of road surface 8, base layer 7 and fill 6, retaining wall 3 produces a small displacement outward. Assuming that rupture surface 9 is the upper edge top surface of the trapezoidal cross section of the composite body, i.e., rupture surface II 92, taking non-cohesive fill as an example, the component force distribution load acting on the composite body is

[0122]

[0123] Where, the Coulomb active earth pressure coefficient and the angle with the horizontal line are

[0124]

[0125] Because there is friction and The load component in the axial direction produces shear deformation. Any axis direction The axial load strength at

[0126]

[0127] Perpendicular to Any axis direction The load intensity at

[0128]

[0129] To simplify the calculation, it is assumed that the frictional resistance of the complex The load component in the axial direction is The axial flexural deformation is irrelevant. The microelement analysis of the complex is performed. The moment of the center of the right side of the microelement is taken. ,have

[0130] Neglecting the second-order trace, we get

[0131]

[0132] Depend on The resultant force in the axial direction is equal to Available

[0133]

[0134] The relationship between the bending moment and deflection of the elastic foundation beam

[0135]

[0136] From the above equations, the differential equation of the elastic foundation beam is:

[0137] In the formula

[0138]

[0139] Formula 2:

[0140] The differential equation in formula 1 is a variable coefficient ordinary differential equation, which can be solved by power series, but the solution process is very complicated. Now we use the fifth power series to fit. Let ,have to

[0141]

[0142] Here we assume that the two ends of the elastic foundation beam , It also conforms to the Winkler assumption that the two end points , The displacement is caused by the shear force The boundary conditions and load conditions give

[0143] The fifth power series coefficient and the two ends of the elastic foundation beam are obtained from the boundary conditions , of for

[0144]

[0145] Substitution Can be found and

[0146] Substituting the above five coefficients into Formula 2, we get the solution of elastic foundation beam fitting;

[0147] In formula 2, when the variable cross-section rate of the elastic foundation beam is Or smaller, take Simplify the calculation of uniform cross-section beams, or simplify the variable cross-section of elastic foundation beams into stepped beams. Segment calculation, each segment takes For equal cross-sections, a differential equation group is listed for calculation according to the continuity conditions, but the number of segments should not be too many to avoid increasing the amount of calculation work;

[0148] Formula 3:

[0149] In order to obtain the maximum bending moment of the elastic foundation beam, let ,Right now

[0150]

[0151] If we can find the interval in the above equation Real roots in , we can get the maximum and maximum values ​​of the bending moment of the elastic foundation beam, and analyze whether the maximum value is reasonable in combination with the actual problem, discard the unreasonable maximum value, and then press Value application;

[0152] Similarly, in order to obtain the maximum shear force of the elastic foundation beam, let ,Right now

[0153]

[0154] If we can find the interval in the above equation Real roots in , we can get the maximum and maximum values ​​of the shear force of the elastic foundation beam, and analyze whether the maximum value is reasonable in combination with the actual problem, discard the unreasonable maximum value, and then press

[0155]

[0156] Value application;

[0157] Formula 4:

[0158]

[0159] The symbols in Formula 1, Formula 2, Formula 3 and Formula 4 are defined as:

[0160] ——respectively the width of the elastic foundation beam, the horizontal thickness of the upper end of the elastic foundation beam, the horizontal thickness of the lower end of the elastic foundation beam, and the thickness of any part of the elastic foundation beam. The cross-sectional height, the diagonal length of the elastic foundation beam, the width of the vehicle load, the length of the vehicle load, ;

[0161] ——respectively the height of the retaining wall 3, i.e. the vertical height from the lower end to the upper end of the elastic foundation beam, the thickness of the base layer 7, and the thickness of the road surface 8, ;

[0162] ——respectively are vehicle weight and vehicle equivalent fill 6 vertical load strength, ;

[0163] ——When vehicle load and active earth pressure of pavement 8, base 7 and fill 6 act on any part of the composite The component distributed load at ;

[0164] ——When vehicle load and active earth pressure of pavement 8, base 7 and fill 6 act on any part of the center line of the composite The axial distributed load at ;

[0165] ——When vehicle load and active earth pressure of pavement 8, base 7 and fill 6 act on any part of the center line of the composite The vertical distributed load at ;

[0166] —— foundation reaction force of elastic foundation beam, ;

[0167] ——coefficient of foundation reaction of elastic foundation beam, Obtained from reference materials or actual measurements, dimensionless, ;

[0168] ——The total pressure of the sum of vehicle load and structural load on the top of the elastic foundation beam, the internal friction angle of the fill 6, and the friction angle of the back of the retaining wall 3, ;

[0169] ——Poisson’s ratio of the elastic foundation beam composed of the composite body, Coulomb’s earth pressure coefficient of the vehicle load and the structural load above the top surface of the elastic foundation beam, dimensionless;

[0170] ——are respectively the elastic modulus of the elastic foundation beam of the composite, the elastic modulus of the geocell 4, the elastic modulus of the binder 5, and the elastic modulus of any part of the elastic foundation beam The moment of inertia of the cross section, the moment of inertia of the cross section at the lower end of the elastic foundation beam, the moment of inertia of the cross section at the upper end of the elastic foundation beam, the elastic modulus proportional coefficient of the geocell in the elastic foundation beam composite, and the elastic modulus proportional coefficient of the binder in the elastic foundation beam composite, where Determined by experiment, , dimensionless;

[0171] ——Deformation of elastic foundation beam caused by Friction per unit length in the direction, ;

[0172] ——Deformation of elastic foundation beam caused by Directional pull, ;

[0173] ——respectively the center origin of the lower end of the inclined elastic foundation beam of Axis, Axis vertical axis, ;

[0174] ——respectively the angle between the elastic foundation beam and the horizontal line, and the angle of the cross-section change rate of the linear variable cross-section elastic foundation beam , ;

[0175] ——Number 1, 2, 3....;

[0176] ——They are respectively the deflection curve of the elastic foundation beam under load, the deflection curve fitted by the fifth power series, and the lower end of the elastic foundation beam fitted by the fifth power series The deflection at the top of the elastic foundation beam fitted by the fifth power series The deflection at ;

[0177] ——respectively, the weight of the road surface 8, the weight of the base layer 7, the weight of the fill 6, and the weight of the composite body, ;

[0178] ——are the elastic foundation beams at any position under load The bending moment of the elastic foundation beam at any point of the fifth power series fitting The bending moment and elastic foundation beam are at the lower end of the fifth power series fitting The bending moment at the elastic foundation beam is at the upper end of the fifth power series fitting The bending moment at ;

[0179] ——are the elastic foundation beams at any position under load The shear force and elastic foundation beam are fitted at any point of the fifth power series. The shear force and elastic foundation beam are at the lower end of the fifth power series fitting The shear force and elastic foundation beam at the upper end of the fifth power series fitting The shear force at ;

[0180] ——are the unknown coefficients of the elastic foundation beam in the fifth power series fitting, .

[0181] The rupture surface 9 is formed when the fill 6 generates active earth pressure under the action of vehicle load, road surface 8 and base layer 7, causing the retaining wall 3 to slide to the outside of the roadbed or rotate around a certain point of the retaining wall foundation, so that cracks are generated in the fill 6 from a certain height of the retaining wall 3 to the road surface. The crack forms a rupture surface 9 along the longitudinal direction of the half-cut and half-filled roadbed structure. The formation of the rupture surface destroys the integrity of the half-cut and half-filled roadbed structure and the road surface fill, resulting in water seepage and subsidence inside the half-cut and half-filled roadbed structure, serious roadbed sliding, and half-filled roadbed collapse.

[0182] For a half-cut and half-filled roadbed structure, a rupture surface, namely, rupture surface Ⅰ91, is most likely to occur at the junction of the half-cut and half-filled roadbed structure. Therefore, multiple steps are excavated at the half-cut and half-filled joint, and reinforced with a composite of geocell 4 and binder 5 to move the hypothetical rupture surface Ⅰ91 to rupture surface Ⅱ92, thereby reducing the active earth pressure of the fill 6, reducing the number of retaining wall 3 projects, and achieving economic savings. If the possible rupture surface 9 passes through the composite, the composite has a strong shear resistance, preventing the retaining wall 3 from sliding to the outside of the roadbed or rotating around a certain point of the retaining wall foundation, thereby improving the stability of the half-cut and half-filled roadbed structure.

[0183] The construction method of the ecological half-cut and half-fill roadbed structure of a mountain highway mainly includes the following steps:

[0184] Step 1: Determine the size of the geocell and binder composite

[0185] According to the cross-sectional dimensions and geological conditions of the half-cut and half-filled roadbed structure determined in the design drawings, the composite dimensions of the geocell 4 and the binder 5 are initially planned;

[0186] Determine the material performance index of the geocell 4, the performance index of the binder 5 and the performance index of the composite through experiments;

[0187] ③ Calculate and verify the structures of retaining wall 3, filling 6 and the complex by formula 1, formula 2, formula 3 and formula 4, and determine the engineering materials and technical indicators;

[0188] Step 2: Excavation of roadbed

[0189] Measure and stake out according to the design drawings and determine the excavation line;

[0190] ② Mechanical equipment enters the site, excavates the roadbed and retaining wall foundation from top to bottom, and transports the excavated material to the yard for storage;

[0191] ③ Excavate the steps at the junction of the half-cut and half-filled roadbed structure, and keep each step 21 on the same horizontal plane along the longitudinal direction of the route, and the quality meets the design requirements;

[0192] Step 3: Retaining wall, fill and composite construction

[0193] Clean the retaining wall foundation and ensure that the bearing capacity meets the design requirements;

[0194] ② Taking the construction of a cement concrete retaining wall with three layers and each section of 15m to 20m in the longitudinal direction as an example, mix the cement concrete mixture, place the formwork, pad the settlement joint material between the foundations of each section of the retaining wall, pump and cast the cement concrete retaining wall foundation, lay the geotextile and sprinkle water for curing to the design requirements; clean the concrete scum on the top surface of the foundation and roughen the surface; erect the lower retaining wall formwork, pad the settlement joint material between the wall of each section of the retaining wall, pump and cast the cement concrete retaining wall body; and inspect the quality to meet the design requirements;

[0195] ③Clear the step foundation at the junction of the half-excavation and half-fill roadbed structure, and the bearing capacity meets the design requirements;

[0196] ④ The geocell 4 is laid horizontally on the bottom step toward the retaining wall to the designed width and vertically toward the route direction. The geocell material is tightened to open each geocell and then fixed with soil nails. The geocell 4 is laid continuously on each retaining wall. The vertical penetration rate of the holes of the geocell is not less than 70%, so as to facilitate the pouring of semi-fluid geopolymer concrete.

[0197] ⑤ Set up a fixed formwork on the outside of the geocell, close to the edge of the geocell;

[0198] Pump semi-fluid geopolymer concrete into each geocell. If it is not dense, insert a small vibrator into the geocell to vibrate. The vibrator cannot touch the HDPE sheet material of geocell 4. The top surface needs to be smoothed with a trowel, and geotextiles are laid and watered to maintain to the design requirements. The inspection quality meets the design requirements.

[0199] Backfill 6 simultaneously and compact it with small machinery;

[0200] Follow step 3④~ Simultaneously construct the geocell, binder and layered fill to the first retaining wall and level it, then follow step 3②~ The second layer of retaining wall, geocell, binder and layered fill are constructed simultaneously. Then follow step 3②~ The third layer of retaining wall, geocell, binder and layered filling are constructed simultaneously until the top surface of the road surface; when the binder is low-grade cement mortar, low-grade cement concrete or cement stabilized soil, the above method is similar;

[0201] Simultaneously check that the fill compaction meets the design requirements;

[0202] Step 4: Base and pavement construction

[0203] Measure and stake out to determine the elevation of the base layer:

[0204] ② Lay the base layer 7 in layers and compact it;

[0205] ③Measure and stake out to determine the elevation of the road surface:

[0206] ④ The machinery and equipment are in place, and the road materials are mixed and transported to the site for paving operations;

[0207] ⑤ Roll the road mixture and conduct inspection and acceptance according to standards.

[0208] Therefore, the present invention is a geocell reinforcement method for a semi-excavation and semi-filling roadbed with a simple structure, economic applicability, environmental protection, energy conservation and emission reduction, which embodies the concept of green engineering construction. Combined with the corresponding construction method, it has high economic and social benefits.

[0209] The embodiments of the present invention are only used to illustrate the present invention and are not used to limit the scope of the present invention. It should also 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 limited by the appended claims of the present application.

Claims

1. An ecological half-cut and half-filled roadbed structure for a mountain highway, comprising: excavating an excavation line (2) on a ground line (1) of a natural mountain slope, excavating a half-cut and half-filled joint into multiple steps (21), and building a retaining wall (3) on the shoulder portion, characterized in that A plurality of geocells (4) are laid on the multi-step steps (21), a semi-fluid binder (5) is poured in the multi-step geocells, and a composite of the geocells and the binder is formed; a fill (6) is built between the composite and the retaining wall (3); a road base (7) and a road surface (8) are sequentially laid on the composite and the fill (6) in the retaining wall (3), and a geocell (4) reinforced, ecological, semi-cut and semi-filled roadbed and road surface stable structure for vehicle traffic is formed; a plurality of drainage pipes (31) are buried in the composite, the fill (6) and the retaining wall (3), and each drainage pipe (31) is a plurality of drainage pipes (31) and ... The drainage pipes all extend out of the retaining wall (3) to discharge the seepage water; the multi-layer geocell (4) is laid from bottom to top on the multi-step steps (21) of the excavation line, and the multi-layer geocell (4) extends a certain length in the direction of the retaining wall (3) and extends in the longitudinal direction of the half-cut and half-filled roadbed structure; the composite of the geocell (4) and the binder (5) and the multi-step steps (21) of the excavation line (2) form an overall oblique composite from bottom to top and from the horizontal to the vertical direction, and the cross section of the composite is generally an oblique trapezoid with unequal thickness at the upper and lower ends, and the oblique length of the center line of the trapezoid is , the angle with the horizontal line is , the horizontal thickness of the lower end is , the horizontal thickness of the upper end is , the angle of the variable section is , starting from the center line of the lower end of the trapezoid To the midpoint of the upper centerline for axis; assuming that the longitudinal length of the composite along the half-cut and half-filled roadbed structure is much greater than the oblique length , so take the longitudinal length As the width of the complex of the inclined trapezoid, the complex is regarded as a one-dimensional variable thickness elastic foundation beam. The two ends of the elastic foundation beam are elastically hinged. According to the Winkler assumption, the foundation reaction force of the elastic foundation beam is , the equivalent vertical load strength of the vehicle weight is ; The following calculation formula is obtained from Coulomb's earth pressure theory, elastic mechanics and the principle of force balance: Formula 1: Under the action of vehicle load and active earth pressure of road surface (8), base (7) and fill (6), the retaining wall (3) produces a small displacement outward. Assuming that the rupture surface (9) is the top edge of the trapezoidal cross section of the composite body, that is, rupture surface II (92), taking non-cohesive fill as an example, the component force distribution load acting on the composite body is Where, the Coulomb active earth pressure coefficient and the angle with the horizontal line are Because there is friction and The load component in the axial direction produces shear deformation. Any axis direction The axial load strength at Perpendicular to Any axis direction The load intensity at To simplify the calculation, it is assumed that the frictional resistance of the complex The load component in the axial direction is The axial flexural deformation is irrelevant. The microelement analysis of the complex is performed. The moment of the center of the right side of the microelement is taken. ,have Neglecting the second-order trace, we get Depend on The resultant force in the axial direction is equal to Available The relationship between the bending moment and deflection of the elastic foundation beam From the above equations, the differential equation of the elastic foundation beam is: In the formula Formula 2: The differential equation in formula 1 is a variable coefficient ordinary differential equation, which can be solved by power series, but the solution process is very complicated. Now we use the fifth power series to fit. Let ,have to Here we assume that the two ends of the elastic foundation beam , It also conforms to the Winkler assumption that the two end points , The displacement is caused by the shear force The boundary conditions and load conditions give The fifth power series coefficient and the two ends of the elastic foundation beam are obtained from the boundary conditions , of for Substitution Can be found and Substituting the above five coefficients into Formula 2, we get the solution of elastic foundation beam fitting; In formula 2, when the variable cross-section rate of the elastic foundation beam is Or smaller, take Simplify the calculation of uniform cross-section beams, or simplify the variable cross-section of elastic foundation beams into stepped beams. Segment calculation, each segment takes For equal cross-sections, a differential equation group is listed for calculation according to the continuity conditions, but the number of segments should not be too many to avoid increasing the amount of calculation work; Formula 3: In order to obtain the maximum bending moment of the elastic foundation beam, let ,Right now If we can find the interval in the above equation The real roots of , we can get the maximum and maximum values ​​of the bending moment of the elastic foundation beam, and analyze whether the maximum value is reasonable in combination with the actual problem, discard the unreasonable maximum value, and then press Value application; Similarly, in order to obtain the maximum shear force of the elastic foundation beam, let ,Right now If we can find the interval in the above equation Real roots in , we can get the maximum and maximum values ​​of the shear force of the elastic foundation beam, and analyze whether the maximum value is reasonable in combination with the actual problem, discard the unreasonable maximum value, and then press Value application; Formula 4: The symbols in Formula 1, Formula 2, Formula 3 and Formula 4 are defined as: ——respectively the width of the elastic foundation beam, the horizontal thickness of the upper end of the elastic foundation beam, the horizontal thickness of the lower end of the elastic foundation beam, and the thickness of any part of the elastic foundation beam. The cross-sectional height, the diagonal length of the elastic foundation beam, the width of the vehicle load, the length of the vehicle load, ; ——respectively the height of the retaining wall (3), i.e. the vertical height from the lower end to the upper end of the elastic foundation beam, the thickness of the base layer (7), and the thickness of the road surface (8), ; ——respectively are the vehicle weight and the equivalent fill volume of the vehicle (6) vertical load strength, ; ——When vehicle load and active earth pressure of pavement (8), base (7) and fill (6) act on any part of the composite The component distributed load at ; ——When vehicle load and active earth pressure of pavement (8), base (7) and fill (6) act on any part of the composite centerline The axial distributed load at ; ——When vehicle load and active earth pressure of pavement (8), base (7) and fill (6) act on any part of the composite centerline The vertical distributed load at ; —— foundation reaction force of elastic foundation beam, ; ——coefficient of foundation reaction of elastic foundation beam, Obtained from reference materials or actual measurements, dimensionless, ; - the total pressure of the sum of the vehicle load and the structural load on the top of the elastic foundation beam, the internal friction angle of the fill (6), and the friction angle of the back of the retaining wall (3), ; ——Poisson’s ratio of the elastic foundation beam composed of the composite body, Coulomb’s earth pressure coefficient of the vehicle load and the structural load above the top surface of the elastic foundation beam, dimensionless; ——are respectively the elastic modulus of the elastic foundation beam of the composite, the elastic modulus of the geocell (4), the elastic modulus of the binder (5), and the elastic modulus of any part of the elastic foundation beam. The moment of inertia of the cross section, the moment of inertia of the cross section at the lower end of the elastic foundation beam, the moment of inertia of the cross section at the upper end of the elastic foundation beam, the elastic modulus proportional coefficient of the geocell in the elastic foundation beam composite, and the elastic modulus proportional coefficient of the binder in the elastic foundation beam composite, where Determined by experiment, , dimensionless; ——Deformation of elastic foundation beam caused by Friction per unit length in the direction, ; ——Deformation of elastic foundation beam caused by Directional pull, ; ——respectively the center origin of the lower end of the inclined elastic foundation beam of Axis, Axis vertical axis, ; ——respectively the angle between the elastic foundation beam and the horizontal line, and the angle of the cross-section change rate of the linear variable cross-section elastic foundation beam , ; ——Number 1, 2, 3....; ——They are respectively the deflection curve of the elastic foundation beam under load, the deflection curve fitted by the fifth power series, and the lower end of the elastic foundation beam fitted by the fifth power series The deflection at the top of the elastic foundation beam fitted by the fifth power series The deflection at ; ——the weight of the pavement (8), the weight of the base (7), the weight of the fill (6), and the weight of the composite, respectively, ; ——are the elastic foundation beams at any position under load The bending moment of the elastic foundation beam at any point of the fifth power series fitting The bending moment and elastic foundation beam are at the lower end of the fifth power series fitting The bending moment at the elastic foundation beam is at the upper end of the fifth power series fitting The bending moment at ; ——are the elastic foundation beams at any position under load The shear force and elastic foundation beam are fitted at any point of the fifth power series. The shear force and elastic foundation beam are at the lower end of the fifth power series fitting The shear force and elastic foundation beam at the upper end of the fifth power series fitting The shear force at ; ——are the unknown coefficients of the elastic foundation beam in the fifth power series fitting, ; The rupture surface (9) refers to the active earth pressure generated by the fill (6) under the joint action of vehicle load, road surface (8) and base layer (7), which pushes the retaining wall (3) to slide to the outside of the roadbed or rotate around a certain point of the retaining wall foundation, and causes cracks in the fill (6) from a certain height of the retaining wall to the road surface (8). The crack forms a rupture surface along the longitudinal direction of the half-cut and half-filled roadbed. A complex of a geocell (4) and a binder (5) is set on the roadbed at the junction of the half-cut and half-filled, and the rupture surface (9) that is most likely to be generated at the junction is moved outward, thereby reducing the earth pressure of the fill (6) and reducing the number of retaining wall (3) projects.

2. The ecological half-cut and half-filled roadbed structure for mountain roads according to claim 1 is characterized in that The geocell (4) is a three-dimensional mesh cell structure formed by high-strength welding of reinforced HDPE sheet materials. The plane size or height of a single geocell (4) is 15 cm to 25 cm, and the HDPE sheet material constituting the geocell is vertically porous.

3. The ecological half-cut and half-filled roadbed structure for mountain roads according to claim 1 is characterized in that The binder (5) is a semi-fluid geopolymer concrete, which is composed of geopolymer, cement and sand and gravel, and is in a fluid state and is easy to be poured into the geocell.

4. The ecological half-cut and half-filled roadbed structure for mountainous highway according to claim 1 is characterized in that The overall structure of the composite conforms to Hooke's law, and the Poisson's ratio of the lateral strain to the vertical strain is The fill is a loose structure, and its active earth pressure coefficient Greater than The complex is set to be wider at the bottom and narrower at the top, or narrower at the bottom and wider at the top, or the same size at the top and bottom according to actual conditions.

5. The ecological half-cut and half-filled roadbed structure for mountainous highway according to claim 1 is characterized in that The drainage pipe (31) is a PVC pipe, one end of which is in close contact with the outer edge of the complex, and the other end of which extends 10 cm to 20 cm outside the retaining wall (3). Each drainage pipe (31) is provided with a plum blossom-shaped seepage hole and is covered with geotextile, and the drainage slope is 1% to 2%.

6. The ecological half-cut and half-filled roadbed structure for mountainous highway according to claim 1 is characterized in that The ground line (1) is a cross-sectional line of the ground on the mountain road route and serves as a reference line for the longitudinal and cross-sectional design of the semi-cut and semi-filled roadbed structure; the excavation line (2) is a line connecting the parts of the cross section that need to be excavated determined according to the excavation depth at the center of the road route.

7. The ecological half-cut and half-fill roadbed structure for mountainous highway according to claim 1 is characterized in that The retaining wall (3) is a gravity retaining wall, which is constructed of block stones and reinforced concrete; the width of each step (21) is not less than 1.0m, and the height of each step is not less than 0.3m; the fill (6) is formed by rolling and compacting ordinary soil, slag and gravel excavated from the slope; the base layer (7) is formed by rolling and compacting cement stabilized soil; and the road surface (8) is a cement concrete road surface or an asphalt concrete road surface.

8. A construction method for an ecological half-cut and half-filled roadbed structure for a mountain highway according to any one of claims 1 to 7, characterized in that The construction method comprises the following steps: Step 1: Determine the size of the geocell and binder composite ① Based on the cross-sectional dimensions of the half-cut and half-fill roadbed structure and the geological conditions determined in the design drawings, the composite dimensions of the geocell (4) and the binder (5) are initially estimated; ② Determine the material performance index of the geocell (4), the performance index of the binder (5) and the performance index of the composite through experiments; ③ Using Formula 1, Formula 2, Formula 3 and Formula 4, calculate and verify the structures of the retaining wall (3), fill (6) and the complex, and determine the engineering materials and technical indicators; Step 2: Excavation of roadbed ①Measure and stake out according to the design drawings and determine the excavation line; ② Mechanical equipment enters the site, excavates the roadbed and retaining wall foundation from top to bottom, and transports the excavated material to the yard for storage; ③ Excavate the steps at the junction of the half-cut and half-fill roadbed structure, and keep each step (21) on the same horizontal plane along the longitudinal direction of the route, and the quality meets the design requirements; Step 3: Retaining wall, fill and composite construction ①Clean the retaining wall foundation and ensure that the bearing capacity meets the design requirements; ② Taking the construction of cement concrete retaining wall with three layers and each section of 15m to 20m in the longitudinal direction as an example, mix the cement concrete mixture, place the formwork, pad the settlement joint material between each section of the retaining wall foundation, pump and cast the cement concrete retaining wall foundation, lay the geotextile and sprinkle water for curing to the design requirements; Clean the concrete scum on the top surface of the foundation and roughen the surface; Set up the lower retaining wall formwork, pad the settlement joint material between each retaining wall section, and pump and pour cement concrete retaining wall; the inspection quality meets the design requirements; ③Clear the step foundation at the junction of the half-excavation and half-fill roadbed structure, and the bearing capacity meets the design requirements; ④ The geocell is laid horizontally on the bottom step toward the retaining wall to the designed width and vertically toward the route direction. The geocell material is tightened to open each geocell and then fixed with soil nails. The geocell (4) is laid continuously on each retaining wall. The vertical penetration rate of the holes of the geocell is not less than 70%, so as to facilitate the pouring of semi-fluid geopolymer concrete. ⑤ Set up a fixed formwork on the outside of the geocell, close to the edge of the geocell; ⑥ Pump semi-fluid geopolymer concrete into each geocell. If it is not dense, insert a small vibrator into the geocell to vibrate. The vibrator cannot touch the HDPE sheet material of the geocell. The top surface needs to be smoothed with a trowel, and the geotextile is laid and watered to maintain it to the design requirements. The inspection quality meets the design requirements; ⑦ Simultaneously backfill the fill (6) and compact it with a small machine; ⑧According to step 3④~⑦, geocell, binder and layered filling are constructed synchronously until the first layer of retaining wall is flush, and then according to step 3②~⑦, the second layer of retaining wall, geocell, binder and layered filling are constructed synchronously, and then according to step 3②~⑦, the third layer of retaining wall, geocell, binder and layered filling are constructed synchronously until the top surface of the road surface; when the binder adopts low-grade cement mortar, low-grade cement concrete or cement stabilized soil, the above method is similar; ⑨Simultaneously check that the compaction degree of the filling meets the design requirements; Step 4: Base and pavement construction ①Measure and stake out to determine the elevation of the base layer: ② Lay the base layer (7) in layers and compact it; ③Measure and stake out to determine the elevation of the road surface: ④ The machinery and equipment are in place, and the road materials are mixed and transported to the site for paving operations; ⑤ Roll the road mixture and conduct inspection and acceptance according to standards.

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