Ecological retaining wall and design method thereof

Abstract

The invention discloses an ecological retaining wall and a design method thereof.The design method comprises the steps that the type and the embedding depth of a retaining wall foundation are determined according to actual geological conditions; a cantilever plate is arranged on the retaining wall foundation; an intercepting ditch is formed in the top of the side slope, a drainage ditch is formed in the bottom of the side slope, a flowing water step groove is designed between the intercepting ditch and the drainage ditch, a sand basin is arranged on the bottom face of the flowing water step groove, and drainage holes are formed in the wall face and inserted into filling soil in the wall face along the wall face. Sandy soil is filled between the cantilever plates, organic soil is filled on the surface layer after compaction, and vegetation is planted according to the thickness of the filled soil; wherein during soil filling, stability calculation is carried out by using Sarma to determine parameters of soil filling, so that arc-shaped sliding of soil filling is avoided. The method is simple in design process and clear in force transmission path, so that the retaining wall has good long-term stability and has good popularization and application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of geotechnical engineering, and in particular to an ecological retaining wall and a design method thereof. Background Art

[0002] A retaining wall is a structure used to support embankment fill or hillside soil to prevent the soil from deforming or becoming unstable. A gravity retaining wall is a common form of retaining wall, which uses the deadweight of the retaining wall to maintain its stability. The existing gravity retaining wall consists of a foundation and a wall. The foundation is located on the foundation, and the connection surface between the wall and the foundation is the wall. The connection surface between the walls is relatively weak. Under the action of soil pressure, the wall will be squeezed to one side, resulting in the collapse of the retaining wall.

[0003] With the rapid development of urbanization and economy, the design of retaining walls encounters more and more problems in work. It is particularly important to make the retaining wall safe and economical, reasonable and beautiful, solve the visual bulkiness of the retaining wall, make it harmonious with the natural environment and maintain long-term stable existence. Summary of the invention

[0004] In view of this, an object of the present invention is to provide an ecological retaining wall and a design method thereof, so as to at least partially solve the above-mentioned problems.

[0005] An embodiment of the present invention provides a design method for an ecological retaining wall, which includes:

[0006] Determine the type and embedment depth of retaining wall foundation according to actual geological conditions;

[0007] Setting cantilever slab on retaining wall foundation;

[0008] A water interception ditch is set at the top of the slope, a drainage ditch is set at the bottom of the slope, and a water flow tread groove is designed between the interception ditch and the drainage ditch. A sedimentation tank is set at the bottom of the water flow tread groove, and a drainage hole is set on the wall surface. The drainage hole is inserted into the fill soil on the wall surface along the wall surface;

[0009] Sandy soil is filled between the cantilever slabs, and organic soil is filled on the surface after compaction, and vegetation is planted according to the thickness of the fill. When filling the soil, Sarma is used to perform stability calculations to determine the parameters of the fill to avoid arc-shaped sliding of the fill.

[0010] Preferably, determining the type of retaining wall foundation includes:

[0011] When the bearing capacity of the foundation is insufficient and the terrain at the wall site is flat, the retaining wall is built directly on the shallow foundation on the natural foundation;

[0012] If there is a short gap in the foundation or it is difficult to dig the foundation, an arch foundation is used, spanned by a stone arch ring, and then the wall is built on it;

[0013] If the foundation is a soft soil layer, hard materials are used to replace it to diffuse the compressive stress of the base and transfer it evenly to the underlying soft soil layer.

[0014] Preferably, determining the embedding depth of the retaining wall foundation includes:

[0015] When there is no scouring, it should be no less than 1.0m below the natural ground surface;

[0016] When there is scouring, it should be no less than 1.0m below the scouring line;

[0017] When affected by frost heave, it should be no less than 0.25m below the ice line.

[0018] Preferably, it also includes:

[0019] When the retaining wall foundation is set on rock, remove the surface weathered layer;

[0020] When the weathered layer is too thick to be completely removed, the basement shall be buried in the weathered layer according to the weathering degree of the foundation and its corresponding allowable bearing capacity;

[0021] When the horizontal slope of the ground in front of the wall toe is large, the foundation embedment depth is controlled by the width of the safety flange in front of the wall toe to prevent shear damage to the foundation.

[0022] Preferably, the cantilever plate adopts a corrosion-resistant structure, and ensures that the cantilever plate of the retaining wall will not be deformed too much or even bent and damaged due to the settlement of the fill; wherein:

[0023] For large retaining walls, the corrosion-resistant structure is reinforced concrete;

[0024] For small retaining walls with less surface fill, plain concrete is used. During construction, the fill must be compacted to ensure that the cantilever slab will not bend or break.

[0025] Preferably, the drainage holes are circular holes with a diameter of 5 cm, with a slope of 2% toward the outside of the wall, and are spaced 2 meters apart and arranged in an alternating manner.

[0026] Preferably, for the surface fill, Sarma is used to calculate the stability to avoid circular sliding of the fill; wherein, for the i-th slider soil layer, the sliding force F 下 It is expressed as:

[0027]

[0028] Where V is the volume of the soil layer of the sliding block, l i represents the length of the i-th cantilever plate; hi represents the thickness of the i-th cantilever plate, γ m represents the weighted degree of the sliding block soil layer, θ is the angle between the sliding surface fitted by the sliding block soil layer and the horizontal plane;

[0029] Anti-slip force F 抗 It is expressed as:

[0030]

[0031] Where: H i represents the thickness of the soil layer of the ith slider, C and They represent the cohesion and friction angle of the sliding block soil layer respectively, and τ is the shear strength of the cantilever plate.

[0032] Preferably, a stepped ecological retaining wall is provided for the higher slopes.

[0033] Preferably, the fill design requires that it is thin at the top and thick at the bottom, and the vegetation is mainly small-sized vegetation. The cantilever plate is short at the top and long at the bottom, and passes through the possible sliding surface of the entire soil body.

[0034] The embodiment of the present invention further provides an ecological retaining wall, which is designed by using the above-mentioned design method.

[0035] The present invention achieves the concealment effect of the retaining wall by setting up fill soil and green plants on the wall surface, removes the visually huge and bulky feeling of the retaining wall in the past, solves the problem of the aesthetics of the retaining wall, directly decorates the retaining wall to make it coordinated with the natural environment, and turns the retaining wall with only retaining effect into a natural retaining landscape, giving people a natural aesthetic feeling, and achieving both beautiful and stable effects. The present invention has a simple design process and a clear force transmission path, so that the retaining wall can have good long-term stability and has a good prospect for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the implementation mode will be briefly introduced below. Obviously, the drawings described below are only some implementation modes of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 It is a schematic flow chart of the design method of the ecological retaining wall provided by the first embodiment of the present invention.

[0038] Figure 2 This is the design schematic diagram of the ecological retaining wall.

[0039] Figure 3 Design elevation drawing for ecological retaining wall drainage.

[0040] Figure 4 This is the design drawing of the water stepping trough and sand settling tank.

[0041] Figure 5 This is the stepped design drawing of the ecological retaining wall under the high slope. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] See also Figure 1 The first embodiment of the present invention provides a design method for an ecological retaining wall, which includes:

[0044] S101. Determine the type and embedment depth of the retaining wall foundation according to the actual geological conditions.

[0045] Specifically, the design of the foundation will be based on a detailed investigation of the actual geological conditions, and then the foundation type and burial depth will be determined.

[0046] When the bearing capacity of the foundation is insufficient and the terrain at the wall site is flat, the retaining wall 100 can be directly built on a shallow foundation on the natural foundation.

[0047] If there is a short gap in the foundation or it is difficult to dig the foundation, an arch foundation is used, with a stone arch ring spanning across it, and then the wall is built on it. However, it should be noted that the soil pressure should not be too large to avoid lateral thrust causing cracks in the arch ring.

[0048] When the foundation is a soft soil layer, such as silt, soft clay, etc., it can be replaced with materials such as gravel, crushed stone, slag or lime soil to diffuse the compressive stress of the base and transfer it evenly to the underlying soft soil layer.

[0049] The foundation of the retaining wall 100 should be buried to a sufficient depth depending on the terrain and geological conditions to ensure the stability of the retaining wall. Specifically, the foundation burial depth of the retaining wall set on the soil foundation should meet the following requirements:

[0050] When there is no scouring, it should generally be no less than 1.0m below the natural ground surface;

[0051] When there is scouring, it should be no less than 1.0m below the scouring line;

[0052] When affected by frost heave, the depth should be no less than 0.25m below the ice line. For foundations in non-ice-expansion soil layers, such as rock, pebbles, gravel, medium sand or coarse sand, the burial depth is not limited by the frost depth.

[0053] In addition, when the foundation of the retaining wall 100 is set on the rock, the surface weathering layer should be removed; when the weathering layer is too thick to be completely removed, the base can be buried in the weathering layer according to the weathering degree of the foundation and its corresponding allowable bearing capacity. When the horizontal slope of the ground in front of the wall toe is large, the foundation embedding depth is controlled by the width of the safety flange in front of the wall toe to prevent shear damage to the foundation.

[0054] S102, a cantilever slab is set on the retaining wall foundation.

[0055] In this embodiment, if Figure 2 As shown, in order to prevent the backfill soil from sliding in an arc, the cantilever plate 40 is configured to be shorter at the top and longer at the bottom, passing through the possible sliding surface of the entire soil.

[0056] The cantilever plate 40 is generally made of reinforced concrete, and the reinforcement ensures that the cantilever plate of the retaining wall will not be greatly deformed or even bent due to the settlement of the fill.

[0057] Of course, in some special cases, the cantilever plate can be replaced by other corrosion-resistant structures. For example, for a small retaining wall with less surface fill, plain concrete can be used directly. The key to its construction is that the fill must be compacted to ensure that the cantilever plate will not bend or break.

[0058] S103, a water intercepting ditch 31 is set at the top of the slope, a drainage ditch 32 is set at the bottom of the slope, and a water flow tread groove 33 is designed between the water intercepting ditch 31 and the drainage ditch 33, a sand settling tank 34 is set at the bottom of the water flow tread groove 33, and a drainage hole 35 is set on the wall surface, and the drainage hole 35 is inserted into the fill on the wall surface along the wall surface.

[0059] In this embodiment, the drainage design of the retaining wall can refer to Figures 2 to 4 The size of the drainage hole 35 is a circular hole with a diameter of 5 cm, with a slope of 2% toward the outside of the wall, and a spacing of 2 meters, which is staggered up and down to improve the drainage effect.

[0060] S104, fill sandy soil between the cantilever plates, fill the surface with organic soil after compaction, and plant vegetation according to the thickness of the fill; when filling, use Sarma to perform stability calculation to determine the parameters of the fill to avoid arc-shaped sliding of the fill.

[0061] In this embodiment, after the retaining wall is reasonably set, appropriate fill 20 is added to the wall surface, and vegetation 20 is planted on the fill surface to achieve the effect of concealing the retaining wall. Sandy soil with high mechanical strength is selected for the soil in the middle area of ​​the cantilever plate, and organic soil suitable for vegetation growth is selected for the surface layer. Under the premise of ensuring that the vegetation 20 can grow, the mechanical parameters of the soil are improved as much as possible. During the construction process, the sandy soil filled in the middle of the cantilever plate should be compacted to prevent settlement from causing damage to the cantilever plate.

[0062] In this embodiment, for the surface fill, it is necessary to avoid the fill from sliding in an arc shape.

[0063] Specifically, for the retaining wall, under the active earth pressure, according to the simplified Rankine earth pressure condition, we have:

[0064] Active earth pressure coefficient:

[0065]

[0066] It is the friction angle of the soil in its natural state. If the stability of the most dangerous situation is to be analyzed, the friction angle of the saturated state is taken.

[0067] Microscopically, the soil pressure at any depth can be expressed as:

[0068]

[0069] q is the load distributed behind the retaining wall, which is assumed to be a uniformly distributed load.

[0070] n is the number of soil layers of the sliding block.

[0071] γ i is the natural weight of the soil layer of the i-th slider. Considering that drainage holes are set in this retaining wall, the groundwater level is assumed to be lower than the bottom of the retaining wall, and the water pressure is not considered.

[0072] h i is the thickness of the soil layer of the i-th slider.

[0073] C is the cohesion of soil.

[0074] On this basis, after filling the surface, Sarma can be used to calculate stability to avoid circular sliding of the fill; for the i-th sliding block soil layer, its sliding force F 下 It is expressed as:

[0075]

[0076] Where V is the volume of the soil layer of the sliding block, l i represents the length of the i-th cantilever plate; h i represents the thickness of the i-th cantilever plate, γ m represents the weighted degree of the sliding block soil layer, θ is the angle between the sliding surface fitted by the sliding block soil layer and the horizontal plane; the anti-sliding force F 抗 It is expressed as:

[0077]

[0078] Where τ is the shear strength of the cantilever slab.

[0079] In this embodiment, based on the above stability analysis, the number of layers, volume and other parameters of the fill layer can be determined according to the required stability requirements, thereby ensuring the stability of the fill layer and preventing the fill layer from slipping.

[0080] For example, based on stability analysis, it can be seen that the fill design of the ecological retaining wall requires thin top and thick bottom, which has the same effect on slope stability as the pressure foot. Other parts that are beneficial to stability are not included in the stability calculation as the safety factor of the slope. In order to prevent the influence of vegetation root splitting on the retaining wall structure, the vegetation is mainly small-scale vegetation and is designed according to the fill thickness. In addition, if Figure 5 As shown, for higher slopes, stepped ecological retaining walls can be set up.

[0081] The second embodiment of the present invention further provides an ecological retaining wall, which is designed using the above-mentioned design method.

[0082] The present invention achieves the concealment effect of the retaining wall by setting up fill soil and green plants on the wall surface, removes the visually huge and bulky feeling of the retaining wall in the past, solves the problem of the aesthetics of the retaining wall, directly decorates the retaining wall to make it coordinated with the natural environment, and turns the retaining wall with only retaining effect into a natural retaining landscape, giving people a natural aesthetic feeling, and achieving both beautiful and stable effects. The present invention has a simple design process and a clear force transmission path, so that the retaining wall can have good long-term stability and has a good prospect for promotion and application.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A design method for an ecological retaining wall, suitable for being arranged on a slope, characterized in that: include: Determine the type and embedment depth of retaining wall foundation according to actual geological conditions; Setting cantilever slab on retaining wall foundation; A water interception ditch is set at the top of the slope, a drainage ditch is set at the bottom of the slope, and a water flow tread groove is designed between the interception ditch and the drainage ditch. A sedimentation tank is set at the bottom of the water flow tread groove, and a drainage hole is set on the wall surface. The drainage hole is inserted into the fill soil on the wall surface along the wall surface; Sandy soil is filled between the cantilever slabs, and organic soil is filled on the surface after compaction, and vegetation is planted according to the thickness of the fill. When filling the soil, Sarma is used to perform stability calculations to determine the parameters of the fill to avoid arc-shaped sliding of the fill.

2. The design method of the ecological retaining wall according to claim 1 is characterized in that: Determining the type of retaining wall foundation includes: When the bearing capacity of the foundation is insufficient and the terrain at the wall site is flat, the retaining wall is built directly on the shallow foundation on the natural foundation; If there is a short gap in the foundation or it is difficult to dig the foundation, an arch foundation is used, spanned by a stone arch ring, and then the wall is built on it; If the foundation is a soft soil layer, hard materials are used to replace it to diffuse the compressive stress of the base and transfer it evenly to the underlying soft soil layer.

3. The design method of ecological retaining wall according to claim 1, characterized in that: Determining the embedment depth of retaining wall foundation includes: When there is no scouring, it should be no less than 1.0m below the natural ground surface; When there is scouring, it should be no less than 1.0m below the scouring line; When affected by frost heave, it should be no less than 0.25m below the ice line.

4. The design method of the ecological retaining wall according to claim 1 is characterized in that: Also includes: When the retaining wall foundation is set on rock, remove the surface weathered layer; When the weathered layer is too thick to be completely removed, the basement shall be buried in the weathered layer according to the weathering degree of the foundation and its corresponding allowable bearing capacity; When the horizontal slope of the ground in front of the wall toe is large, the foundation embedment depth is controlled by the width of the safety flange in front of the wall toe to prevent shear damage to the foundation.

5. The design method of ecological retaining wall according to claim 1, characterized in that: The cantilever plate adopts a corrosion-resistant structure and ensures that the cantilever plate of the retaining wall will not be deformed too much or even bent due to the settlement of the fill; among which: For large retaining walls, the corrosion-resistant structure is reinforced concrete; For small retaining walls with less surface fill, plain concrete is used. During construction, the fill must be compacted to ensure that the cantilever slab will not bend or break.

6. The design method of ecological retaining wall according to claim 1, characterized in that: The drainage holes are circular holes with a diameter of 5 cm and a slope of 2% toward the outside of the wall. The spacing between the holes is 2 meters and they are staggered up and down.

7. The design method of ecological retaining wall according to claim 1, characterized in that: The filled soil is divided into n sliding block soil layers; for the i-th sliding block soil layer, its sliding force F 下 It is expressed as: Where V is the volume of the soil layer of the sliding block, l i represents the length of the i-th cantilever plate; h i represents the thickness of the i-th cantilever plate, γ m represents the weighted degree of the sliding block soil layer, θ is the angle between the sliding surface fitted by the sliding block soil layer and the horizontal plane; the anti-sliding force F 抗 It is expressed as: Where: H i represents the thickness of the soil layer of the ith slider, C and They represent the cohesion and friction angle of the sliding block soil layer respectively, and τ is the shear strength of the cantilever plate.

8. The design method of ecological retaining wall according to claim 1, characterized in that: For higher slopes, step-type ecological retaining walls are set up.

9. The design method of ecological retaining wall according to claim 1, characterized in that: The backfill is designed to be thin at the top and thick at the bottom, and the vegetation is small-sized. The cantilever plate is short at the top and long at the bottom, and passes through the possible sliding surface of the entire soil body.

10. An ecological retaining wall, characterized in that: The method is designed according to any one of claims 1 to 9.

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