Construction method for controlling deformation of cut-and-fill roadbed interface by using gabion

Abstract

The application relates to the field of subgrade treatment, and provides a construction method for controlling deformation of a cut-and-fill subgrade interface by using gabion cages, which comprises the following steps: S1, cleaning virtual soil in a filling area and constructing a cleaning, leveling and replacement layer; S2, removing earth and rock in the digging area and cleaning the original subgrade; S3, according to the stratum condition of the cut-and-fill area, material is taken as gabion filling; and according to the stratum deformation modulus of the cut-and-fill subgrade area, the gradation of the gabion filling is set; S4, constructing a gabion retaining wall in the filling area; S5, constructing an area of the filling area which is not provided with the gabion retaining wall and carrying out compaction and backfilling; and S6, constructing a pavement layer and completing road construction of one cut-and-fill area. The application provides a simple, efficient, quality-controllable and cost-economic construction method for treating a cut-and-fill interface, and solves or alleviates the problem of cracks and large settlement of the cut-and-fill interface caused by layer-by-layer compaction and backfilling of the geogrid.

Description

Technical Field

[0001] This application relates to the field of roadbed treatment, and in particular to a construction method for controlling the deformation of the cut-fill roadbed interface using gabion cages. Background Technology

[0002] With the deepening of the national strategy to build a strong transportation network, the expressway network is constantly expanding and improving, the quality of ordinary national highways is being enhanced, and rural roads are being extended. Higher demands are being placed on the safety and comfort of road use. Older roads often have significant elevation differences, leading to reduced road comfort. Under the long-term cyclical action of vehicle loads, deformation further increases, creating stress concentration points. In extreme weather conditions such as torrential rain, this can cause landslides and collapses, seriously endangering people's lives and property.

[0003] Road engineering is a linear project, inevitably involving road construction through mountains and filling in depressions, resulting in cut-fill interfaces. These interfaces are often where the greatest settlement deformation occurs, making them the most difficult locations to control differential settlement. Settlement at the cut-fill interface is highly dependent on the properties of the foundation soil, rainfall conditions, and the depth of the cut-fill. Therefore, conventional methods for controlling differential settlement include adding geogrids to the fill area for layered compaction and backfilling, or implementing soil mixing pile treatment.

[0004] The conventional method for backfilling at the cut-fill interface is to use geogrids for layered compaction. However, due to the complicated construction process, which requires layered compaction and geogrid laying, the construction quality is difficult to control effectively, often resulting in cracks and significant settlement at the cut-fill interface. Using mixing piles to treat the cut-fill interface is generally more expensive and has poor suitability for the strata.

[0005] Therefore, there is an urgent need for a simple, efficient, quality-controllable, and cost-effective method for treating the cut-fill interface. Consequently, an improved technical solution is required to address the shortcomings of the existing technologies. Summary of the Invention

[0006] The purpose of this application is to provide a construction method for controlling the deformation of the cut-fill subgrade interface using gabion cages, so as to solve or alleviate the problem of cracks and large settlement at the cut-fill interface caused by layered compaction backfilling of geogrids.

[0007] To achieve the above objectives, this application provides the following technical solution:

[0008] This application provides a construction method for controlling the deformation of the cut-and-fill subgrade interface using gabion cages. The cut-and-fill subgrade includes a fill area and a cut area within a highway cut-and-fill construction zone, wherein the fill area is a concave area. The method is characterized by comprising:

[0009] Step S1: Clear the loose soil in the filling area and construct a cleaning, leveling, and replacement layer;

[0010] Step S2: Remove the excavated soil and rock from the excavation area and clear the original roadbed;

[0011] Step S3: Select materials as gabion cage filling material according to the strata conditions of the cut-and-fill area; and set the gabion cage filling material gradation according to the deformation modulus of the strata in the cut-and-fill roadbed area.

[0012] Step S4: Construct gabion retaining walls in the fill area, layer the gabion cages to counteract the excavation-fill interface, and fill the gap between the gabion retaining wall and the excavation-fill interface with plain concrete.

[0013] Step S5: Construct the non-gabion retaining wall area in the filling area and compact and backfill it.

[0014] Step S6: Construct the road surface layer, completing the road construction in one excavation and filling area.

[0015] Preferably, the gabion cage comprises galvanized steel wire and is filled with locally sourced graded crushed stone.

[0016] Preferably, the deformation modulus E of the gabion cage is... gb As shown in the following formula:

[0017] ,

[0018] Where: E fill The deformation modulus of compacted fill, in MPa; E sub The original deformation modulus of the roadbed, in MPa; h fill The thickness of the compacted fill is expressed in meters (m) or h. sub The thickness of the original roadbed used in the calculation is in meters.

[0019] Preferably, step S4 involves backfilling the gabion cages in layers, including: backfilling the gabion cages in layers from bottom to top, with the bottom layer being the widest and gradually narrowing upwards; the gabion cage slope ratio is less than 1:2.

[0020] Preferably, step S4 involves filling the gap between the gabion retaining wall and the excavation-fill interface with plain concrete, including: the strength of the plain concrete is not less than C25; the plain concrete for backfilling the gap includes: layered pouring, with each layer generally not exceeding 30cm in thickness; and compaction using an immersion vibrator or a small vibrator.

[0021] Preferably, the gabion cage is made of galvanized steel wire with a length of 2 meters, a width and a height of 1 meter, the main filling material has a compressive strength of not less than 5 MPa and a filling rate of not less than 60%, the minimum size is 1.5 times larger than the mesh size, and the gabion cage retaining wall has a bearing capacity of not less than 200 kPa.

[0022] Preferably, in step S1, the replacement layer is made of graded sand and gravel, 30 cm thick, with a bearing capacity of not less than 200 kPa.

[0023] Preferably, in step S2, the bearing capacity of the original roadbed must be no less than 200 kPa.

[0024] Compared with the closest prior art, the technical solution of this application has the following beneficial effects:

[0025] 1. To simplify and efficiently control the differential settlement of the road surface in the cut and fill areas, gabion retaining walls are used to counter-pressure the cut and fill interface, reducing slope deformation. At the same time, the stiffness of the transition section in the fill area is adjusted to reduce the differential settlement of the road surface.

[0026] 2. This invention allows for the use of locally sourced materials as gabion retaining wall fill. The gabion retaining wall fill gradation and type can be adjusted according to the deformation modulus of the cut-fill roadbed. Combined with the setting of gabion transition sections in the filling area, the stiffness change of the cut-fill interface can be effectively adjusted, reducing differential settlement and improving the comfort and durability of the highway.

[0027] 3. The technology of this invention can be adapted to local conditions to construct gabion retaining walls, thereby reducing deformation in the excavation area and adjusting the stiffness of the filling area to reduce differential settlement; thus, it can economically and effectively control road settlement. Attached Figure Description

[0028] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. Wherein:

[0029] Figure 1 This is a schematic diagram of the construction of the gabion cage controlling the deformation of the cut-fill subgrade interface involved in this application;

[0030] The components are: 1. Excavation area; 2. Filling area; 3. Fill layer; 4. Original roadbed; 5. Compacted fill; 6. Gabion retaining wall; 7. Backfill plain concrete; 8. Road surface layer. Detailed Implementation

[0031] The present application will now be described in detail with reference to the accompanying drawings and embodiments. Various examples are provided by way of explanation and not by way of limitation. In fact, those skilled in the art will recognize that modifications and variations can be made to the present application without departing from the scope or spirit thereof. For example, a feature shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is desirable that the present application encompass such modifications and variations that fall within the scope of the appended claims and their equivalents.

[0032] In the following description, the terms "first / second / third" are used merely to distinguish similar objects and do not represent a specific order of objects. It is understood that "first / second / third" may be interchanged in a specific order or sequence where permitted, so that the embodiments of this application described herein can be implemented in an order other than that illustrated or described herein.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used herein is for the purpose of describing embodiments of this disclosure only and is not intended to limit this disclosure.

[0034] In the description of this application, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and do not require that this application be constructed and operated in a specific orientation, and therefore should not be construed as limiting this application. The terms "connected," "linked," and "set up" used in this application should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; direct connections or indirect connections through intermediate components; wired connections, radio connections, or wireless communication signal connections. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0035] A construction method for controlling the deformation of the cut-fill subgrade interface using gabion cages, wherein the cut-fill subgrade includes a fill area 2 and a cut area 1 in the highway cut-fill construction area, wherein the fill area is a concave area; the improvement is that the method includes:

[0036] Step S1: Clear the loose soil in the filling area and construct the cleaning, leveling, and replacement layer 3.

[0037] Specifically, in the highway excavation and filling construction area, the loose soil in the filling area is cleared, and a clearing and leveling replacement layer 3 is constructed. The replacement layer can be made of graded sand and gravel, 30 cm thick, with a bearing capacity of not less than 200 kPa. The clearing and leveling of the replacement layer can be understood as: first, clearing and leveling the construction surface, then excavating the unsuitable soil layer, backfilling with qualified materials and compacting it to form a new base course that meets the design requirements in terms of strength and stability.

[0038] Specifically, step S1 includes:

[0039] Step S1-1, Cleaning: Remove debris, loose soil, silt, tree roots, and other things that may affect the quality of the project from the construction area.

[0040] Step S1-2, Leveling: Level the cleaned ground or foundation surface to make it level or according to the designed slope to facilitate subsequent construction.

[0041] Steps S1-3, Replacement layer: When the bearing capacity of the foundation soil is insufficient, the original weak soil layer is excavated according to the design requirements and replaced with a material with higher strength and better stability (such as sand, gravel, crushed stone, lime-soil, plain soil, etc.), and compacted in layers. The replacement layer can be 30 cm thick with graded sand and gravel, with a bearing capacity of not less than 200 kPa.

[0042] Step S2: Remove the excavated soil and rock from the excavation area and clear the original roadbed 4. Specifically, step S2 includes:

[0043] Step S2-1: Excavate the earth and rock to be excavated to the design elevation;

[0044] Step S2-2: Clear the original roadbed; clean up the remaining loose soil, debris, tree roots, etc., so that the original roadbed (i.e., the undisturbed natural soil or rock layer) under the earthwork is completely exposed. The roadbed bearing capacity must be no less than 200 kPa, as the basis for subsequent construction.

[0045] Step S3: Select materials as gabion cage filling material according to the strata conditions of the cut-and-fill area; and set the gabion cage filling material gradation according to the deformation modulus of the strata in the cut-and-fill roadbed area.

[0046] Specifically, based on the geological conditions of the excavation and filling area, locally sourced materials from the existing strata are used as gabion cage filling materials. The gabion cages are made of galvanized steel wire, 2 meters long, 1 meter wide and 1 meter high. The compressive strength of the main filling material is not less than 5 MPa, and the filling rate is not less than 60%. The minimum size is 1.5 times larger than the mesh size, and the bearing capacity of the gabion cage retaining wall is not less than 200 kPa. The deformation modulus of the gabion cage is determined based on the deformation modulus of the compacted fill (5) and the deformation modulus of the undisturbed subgrade (4), and is generally between the deformation modulus of the compacted fill and the deformation modulus of the undisturbed subgrade.

[0047] Specifically, the deformation modulus E of the gabion cage gb As shown in the following formula:

[0048] ,in:

[0049] E fill The deformation modulus of compacted fill, in MPa; E sub The original deformation modulus of the roadbed, in MPa; h fill The thickness of the compacted fill is expressed in meters (m) or h. sub The thickness of the original roadbed used in the calculation is in meters.

[0050] Step S4: Construct gabion retaining walls 6 in the fill area, applying layered backfill pressure to the excavation-fill interface, and filling the gap between the gabion retaining walls 6 and the excavation-fill interface with plain concrete. The gabions are backfilled in layers from bottom to top, with the bottom layer being the widest and gradually narrowing upwards. There should be no through-sealing between layers of gabions, and the narrowing area should effectively meet the requirements of gradual change in foundation stiffness.

[0051] Preferably, in the specific embodiments of this application, the gabion retaining wall 6 can be made of galvanized steel wire or a more durable material. The mesh size of the gabion is determined according to the gradation and particle size of the filling material. The overall compression modulus of the gabion can be flexibly set according to the height difference between the excavation and filling interfaces. The required material ratio is determined according to the on-site earthwork filling material.

[0052] Specifically, step S4 includes:

[0053] Step S4-1: Construct gabion retaining wall 6 in the filling area. The gabions are laid to cover part of the wall surface of the filling area to form the gabion retaining wall.

[0054] Step S4-2: Layered backfill interface with gabion cages. Specifically, at the boundary between the cut and fill areas, to prevent settlement or slippage of the fill area, backfill is applied to the outside of the boundary to form a backfill zone. The treatment surface formed by the backfill zone and the cut-fill boundary is the backfill interface. Specifically, when constructing the gabion cage backfill interface, the gabion cages are backfilled in layers from bottom to top, with the bottom layer being the widest and gradually narrowing upwards, with a slope ratio of less than 1:2; continuous joints are not allowed between layers of gabion cages.

[0055] Step S4-3 involves filling the gap between the gabion retaining wall and the cut-fill interface with plain concrete (method 7). This includes backfilling the gap with plain concrete, with a strength not less than C25. Specifically, the plain concrete backfilling process involves layered pouring, with each layer generally not exceeding 30cm in thickness. The concrete is then compacted using an immersion vibrator or a small vibrator to ensure density. Alternatively, micro-expansion concrete can be used instead of plain concrete.

[0056] Step S5: Construct the non-gabion cage retaining wall area in the construction fill zone and compact the backfill. Specifically, construct the non-gabion cage retaining wall area in the construction fill zone and compact the backfill with a compaction coefficient of not less than 0.94 and a bearing capacity of not less than 200 kPa.

[0057] The compacted backfill material can be plain soil, preferably lime-soil, with a volume ratio generally of lime:soil = 1:9 or 2:8. The compaction backfilling steps include:

[0058] Step S5-1: Clean the area outside the gabion retaining wall: Remove debris, tree roots, and silt, and level the base. If the base is weak, it needs to be compacted.

[0059] Step S5-2, Layered Filling: Mechanical compaction is used, with each layer ideally 25-30cm thick, which can be adjusted according to the type of machinery used in the construction. The layers should be kept roughly level. During filling, the moisture content of the filler material must be controlled; compaction is best when it is close to the optimum moisture content. If the moisture content is too low, water should be sprinkled; if it is too high, it should be dried or dry material should be added.

[0060] Step S5-3, perform layered compaction: Mechanical compaction: generally 3-5 passes, starting with light compaction followed by heavier compaction, and starting with slow compaction followed by fast compaction. This gradual increase in pressure achieves layer-by-layer compaction, addressing the issue of uneven compaction between upper and lower layers. The purpose of starting with slow compaction and then increasing speed is to achieve a balance between quality and efficiency through a speed gradient, resolving issues of insufficient compaction or low efficiency. Special attention must be paid to edges and corners to avoid missed compaction.

[0061] Step S5-4: Conduct quality inspection: take samples or conduct in-situ tests (ring cutter method, sand cone method, nuclear density meter, etc.) to test the compaction coefficient and dry density.

[0062] Step S5-5: Repeat steps S5-2 to S5-4, backfilling and compacting layer by layer until the design elevation is reached.

[0063] Step S6: Construct pavement layer 8 to complete road construction in one cut-and-fill area. Specifically, construct the pavement layer with a thickness of 68cm to complete road construction in one cut-and-fill area.

[0064] Preferably, if the pavement layer is compacted with asphalt mixture, the compaction degree is controlled by three stages: initial compaction, intermediate compaction, and final compaction, with the roller speed controlled throughout (initial compaction 2-3 km / h, intermediate compaction 3-4 km / h, final compaction 2-3 km / h).

[0065] S6-1, Initial compaction (stabilization): Use a double-drum roller (static compaction mode) to compact 1-2 times. The purpose is to stabilize the mixture, eliminate paving marks, and prevent displacement during subsequent compaction. The initial compaction temperature must be ≥140℃ (AC-20) or ≥150℃ (AC-13).

[0066] S6-2, Secondary compaction (close compaction): Using a rubber-tired roller (or a double-drum roller in vibration mode), compact 3-4 times. This is the core step to improve compaction (the design compaction degree must be ≥96%). The secondary compaction temperature must be ≥120℃ (AC-20) or ≥130℃ (AC-13).

[0067] S6-3, Final compaction (leveling): Use a double-drum roller (static compaction mode) to compact 1-2 times. The purpose is to eliminate the wheel tracks left by the secondary compaction and ensure that the road surface flatness meets the standard (≤2mm / 3m). The final compaction temperature must be ≥90℃ (AC-20) or ≥100℃ (AC-13). Compaction is strictly prohibited if the temperature is too low (it is easy to cause surface cracking).

[0068] It also includes: S6-4, joint treatment to prevent pavement cracking;

[0069] Including longitudinal joints: When paving multiple pavements, the overlap of adjacent pavements should be cut with a cutting machine before subsequent paving (the cut depth should be 1 / 2-2 / 3 of the surface layer thickness) and coated with tack coat; the overlap width should be controlled at 10-15cm during paving, and the overlap should be compacted first while advancing towards the new paving layer, and then the new paving layer should be compacted to avoid the formation of "steps";

[0070] And including transverse joints: at the end of each day's construction or when work is stopped due to a malfunction, the ends must be cut vertically with a cutting machine (avoiding diagonal joints) to remove loose parts; before the next paving, apply tack coat to the cut joints, the paver screed must span the joint by 5-10cm, and when compacting, first compact transversely (i.e., advance from the old road surface to the new road surface), and then compact longitudinally to ensure that the joints are tight.

[0071] Preferably, if the pavement layer is made of cement compaction, it needs to be roughened or textured: before the concrete initially sets (usually 1-2 hours after paving, when there are no obvious marks when pressed with a finger), use a roughening machine (or manual comb plate) to create transverse textures on the pavement surface (perpendicular to the pavement centerline, 1-2 mm deep, 3-5 mm apart) to enhance the pavement's anti-skid performance and prevent vehicles from skidding in rainy weather; the roughening direction must be perpendicular to the pavement centerline, and the texture must be uniform; and edge trimming: the concrete at the edges and joints of the pavement is manually trimmed to ensure that the edges and corners are straight and without defects.

[0072] Preferably, if the pavement layer is compacted with cement, the process also includes cutting and curing steps to prevent cracking.

[0073] Specifically, joint cutting includes: after the concrete has set (usually 6-12 hours after paving, adjusted according to temperature: 6-8 hours in summer, 10-12 hours in winter), using a joint cutting machine to cut contraction joints (transverse joints, spaced 4-6m apart, with a depth of 1 / 3-1 / 4 of the surface layer thickness) and expansion joints (where the pavement meets the structure); the cuts must be straight to avoid misalignment;

[0074] Maintenance includes: Immediate maintenance after the joint is cut, using methods such as covering with curing cloth and sprinkling water (to keep the road surface moist, with a curing time of ≥7 days) or spraying a curing agent (at a rate of 0.3-0.5 kg / m² to form a protective film); vehicles are strictly prohibited from passing through during the maintenance period (to avoid scratches or damage to the road surface);

[0075] Crack filling includes: after maintenance, cleaning debris from the cracks, injecting polyurethane sealant (or asphalt mastic) to fill the gaps (the surface should be slightly higher than the road surface by 2-3mm) to prevent rainwater from seeping into the base layer and causing damage.

[0076] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A construction method for controlling deformation at a cut-and-fill embankment interface using gabion cages, the cut-and-fill embankment comprising a fill area and a cut area in a cut-and-fill construction area of a highway, the fill area being a concave area; characterized in that, The method comprises: Step S1, cleaning the virtual soil of the filling area, and constructing a cleaning and leveling replacement layer; Step S2, excavating the earthwork of the excavation area, and cleaning the original state of the roadbed; Step S3, according to the stratum condition of the excavation and filling area, taking materials as gabion filler; and setting the gradation of the gabion filler according to the deformation modulus of the stratum of the excavation and filling roadbed area; Step S4, constructing a gabion retaining wall in the filling area, layering the gabion to counter-pressure the excavation and filling interface, and filling the gap between the gabion retaining wall and the excavation and filling interface with backfilling concrete; Step S5, constructing the area of the non-gabion retaining wall in the filling area, and performing compaction backfilling; Step S6, constructing the pavement layer, and completing the road construction of one excavation and filling area; The gabion comprises galvanized steel wire, and the gabion is filled with locally-sourced filling gradation gravel; The gabion cage modulus of deformation E gb As shown in the following formula: ， Wherein: E fill is the deformation modulus of compacted fill, unit: MPa; E sub is the deformation modulus of original subgrade, unit: MPa; h fill is the thickness of compacted fill, unit: m; h sub is the thickness of original subgrade involved in calculation, unit: m.

2. The method according to claim 1, wherein the method is characterized by, Step S4 layering the gabion to counter-pressure the excavation and filling interface comprises: layering the backfilling of the gabion from bottom to top, the lowermost layer of the gabion is filled the widest, and gradually narrows upwards; the slope rate of the gabion is less than 1:

2.

3. The method according to claim 1, wherein the method is characterized by, Step S4 filling the gap between the gabion retaining wall and the excavation and filling interface with backfilling concrete comprises: the strength of the backfilling concrete is not less than C25; the gap backfilling concrete comprises: layering pouring, the thickness of each layer is generally not more than 30 cm; and a plug-in vibrator or a small-sized vibrating rod is used for vibrating and compacting.

4. The method according to claim 1, wherein the method is characterized by, The gabion adopts galvanized steel wire with a length of 2 meters, a width and a height of 1 meter, the compressive strength of the main filling material is not less than 5MPA, the filling rate is not less than 60%, the minimum size is greater than 1.5 times of the mesh, and the bearing capacity of the gabion retaining wall is not less than 200kPa.

5. The method according to claim 1, wherein the method is characterized by, In step S1, the replacement layer adopts graded sand and gravel with a thickness of 30 cm, and the bearing capacity is not less than 200kPa.

6. The method according to claim 1, wherein the method is characterized by, In step S2, the bearing capacity of the original roadbed needs to be not less than 200kPa.

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