Method for treating crack disease of steep cross slope silty soil subgrade base layer

Abstract

The invention relates to the technical field of roadbed disease treatment, in particular to a steep cross slope silt roadbed base crack disease treatment method. The method comprises the following steps: acquiring road data of a crack generation road section; after the road data acquisition of the road section is completed, excavation and re-paving repair operation is performed on the road section; and after excavation, re-paving and repairing operation of the road section is completed, an anti-cracking structure is arranged on the road section according to the road data. According to the method, the road section with the crack damage of the road base structure layer can be repaired and reinforced to prevent the crack damage of the base structure layer from occurring again, so that smooth construction of the later pavement is ensured, and the operation and maintenance cost during operation is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of roadbed disease treatment, and in particular to a method for treating crack diseases in a base layer of a steep transverse slope silt roadbed. Background Art

[0002] The "Code for Design of Building Foundations" (GB 5007-2011) defines "silt" as soil with particles larger than 0.075 mm accounting for no more than 50% of the total mass and a plasticity index (IP) of 10 or less. Silt lacks the advantages of sand, such as high permeability, easy drainage and consolidation, and high shear strength, nor the advantages of clay, such as good waterproofing, resistance to erosion, and high cohesion. Consequently, it exhibits poor mechanical properties in many engineering applications.

[0003] When building roads on silty soil, a certain thickness of surface soil is usually removed and compacted. Then, the soil is filled in layers with slag and vibrated and compacted layer by layer until the design elevation of the top of the roadbed is reached. After a one-year settlement period, the base structure layer (usually including the upper base, lower base and subbase) is constructed. However, after the construction of the base structure layer of such roads is completed, longitudinal cracks of varying degrees will still appear in the base structure layer during the rainy season.

[0004] Chinese invention patent CN202110510952.8 discloses a method for treating longitudinal cracks in soft rock roadbeds, which involves first excavating the soft rock roadbed to the bottom of the roadbed in the section where cracks appear, then laying geocells, and then backfilling with soft rock and soil fillers. The grouting pipe is passed through the grid holes of the geocells to perform grouting operations with a grouting depth greater than the depth of the roadbed diseased area. This method can not only reduce the impact of water on the soft rock roadbed, limit the development of longitudinal cracks in the roadbed, and reduce uneven settlement of the roadbed, but also overcome the non-persistence of the roadbed grouting reinforcement effect, thereby ensuring the long-term stable operation of the road. However, in essence, it is to form the soil into a whole, thereby preventing the occurrence of longitudinal cracks in the soft rock roadbed, ensuring the long-term stability of the reinforced soft rock roadbed, and reducing the risk of secondary diseases. For existing ground with steep cross-slope silt (referring to the original ground after a certain thickness of topsoil has been removed and compacted), not only does the silt soften upon contact with water, significantly reducing the bearing capacity and shear strength of the original ground, leading to cracks in the road base structure built above it, but the original cross-slope gradient is also a major factor in inducing roadbed settlement and localized sideways sliding. Even if the silt is reinforced through the "laying geocells and grouting between the cell meshes" method, it is still prone to overall sideways sliding due to contact with water, which can lead to cracks in the base layer. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for treating crack diseases in the base layer of steep slope silt roadbed, which can at least partially overcome the above-mentioned technical problems, repair the section of the road where crack diseases occur in the base structure layer, and reinforce the section to prevent the recurrence of crack diseases in the base structure layer, thereby ensuring smooth construction of the road surface in the later stage and reducing operation and maintenance costs during operation.

[0006] The present invention provides a method for treating crack damage in the base of a steep transverse slope silt roadbed, comprising: collecting road data of a section where cracks occur; performing excavation, resurfacing and repair operations on the section after the road data collection is completed; and setting an anti-cracking structure on the section according to the road data after the excavation, resurfacing and repair operations are completed.

[0007] Furthermore, the excavation, resurfacing and repair work on the road section includes: excavating downward on the road section, passing through the upper base layer, lower base layer, subbase layer and upper roadbed in sequence until the top surface of the lower roadbed is exposed, and compacting the exposed lower roadbed; laying the upper roadbed material, subbase layer material, lower base layer material and upper base layer material on the compacted lower roadbed in sequence and compacting them layer by layer.

[0008] Furthermore, in the process of excavating the road section downward, the excavation area is reduced layer by layer, forming steps between adjacent layers; before laying the upper roadbed material on the compacted lower roadbed, it also includes laying geogrids on the top surface of the compacted lower roadbed; after laying the upper base material and compacting it, it also includes laying geogrids on the compacted upper base.

[0009] Furthermore, the road data includes the original cross slope and location environment; when the original cross slope is less than 1:5, setting up the anti-cracking structure in the road section according to the road data includes: excavating downward to a first preset elevation on the outside of the drainage ditch of the road section, and building a water-retaining wall above the soil exposed after excavation; when the original cross slope is less than 1:5 and the road section is located in a valley, setting up the anti-cracking structure in the road section according to the road data also includes: excavating downward to a second preset elevation on the lower side of the original ground of the road section, building a retaining wall above the soil exposed after excavation, and filling crushed soil and stone between the retaining wall and the lower roadbed; when the original cross slope is greater than 1:5, setting up the anti-cracking structure in the road section according to the road data also includes: before setting up the retaining wall, setting a plurality of grouting micro piles below the soil exposed after excavating downward to the second preset elevation, and then setting the retaining wall above the grouting micro piles, and the upper part of each of the grouting micro piles is fixedly connected to the retaining wall.

[0010] Furthermore, the first preset elevation is at least 2m lower than the higher side of the original ground; a first impermeable membrane is laid on the bottom surface of the water-blocking wall and on the side facing the drainage ditch, and the first impermeable membrane overlaps with the second impermeable membrane laid at the bottom of the drainage ditch, and the overlapping width is greater than 0.5m; when the length of the water-blocking wall is between 4-8m, an expansion joint is set at the midpoint of the water-blocking wall along the length direction; when the length of the water-blocking wall is greater than 8m, an expansion joint is set at every 4m along the length direction of the water-blocking wall; the water-blocking walls on both sides of the expansion joint are connected by elastic waterproof parts.

[0011] Furthermore, vertical grooves are provided on the facing surfaces of the water-blocking walls on both sides of the expansion joint; the elastic waterproof component includes filler and an elastic belt; the elastic belt includes a telescopic tube arranged along the length direction of the belt, and an expansion tube arranged on both sides of the telescopic tube; a plurality of water-permeable holes are provided on the tube wall of the expansion tube, and each of the water-permeable holes is located on the same side of the elastic belt along the thickness direction, and the expansion tube is filled with the filler; when the water-blocking walls on both sides of the expansion joint are connected by the elastic waterproof component, the two sides of the elastic belt along the width direction are respectively inserted into the grooves on both sides of the expansion joint and the water-permeable holes face the water-facing surface of the water-blocking wall; the telescopic tube is located in the expansion joint.

[0012] Furthermore, the elastic belt is selected from one or more of EPDM rubber, silicone rubber, nitrile rubber, polyurethane elastomer, fluororubber and soft PVC; the filler is selected from one or more of bentonite, super absorbent resin and PVA-PEG cross-linked gel particles.

[0013] Furthermore, a water-permeable cushion layer is attached to the inner wall of the expansion tube, and the water-permeable cushion layer is selected from one or more of PTFE microporous membrane, nylon 66 microporous membrane, PP microporous membrane and non-woven fabric.

[0014] Furthermore, the second preset elevation is at least 2m lower than the lower side of the original ground; the crushed soil and stone filled between the retaining wall and the lower roadbed are spread and rolled in layers with a compaction degree greater than 96% until the crushed soil and stone are flush with the top of the retaining wall.

[0015] Furthermore, the road data also includes the direction of the cracks in the road section, and the length direction of the base wall is parallel to the direction of the cracks in the road section.

[0016] Furthermore, the guardrail and the water-retaining wall are both concrete cast walls, and steel cages are provided in the guardrail and the water-retaining wall; when the guardrail and the water-retaining wall are both provided on the road section, the steel cage in the guardrail and the steel cage in the water-retaining wall are connected by tie bars; the tie bars are selected from one or more of threaded steel bars and steel cables.

[0017] Furthermore, the method of setting up a plurality of grouting micro piles below the soil exposed after excavating downward to the second preset elevation includes: S11, after excavating downward to the second preset elevation, continuing to excavate downward by 1.2 m and compacting the exposed soil; S12, determining the location of the grouting micro piles on the surface of the compacted soil, drilling downward to a preset depth at each location and cleaning the hole to obtain an installation hole; S13, inserting a steel anchor pipe and a grouting pipe into the installation hole; the bottom end of the steel anchor pipe is closed and the top end is open, and a bracket is fixedly connected to the bottom of the steel anchor pipe. The top of the steel anchor pipe is flush with the second preset elevation; the top of the grouting pipe is higher than the second preset elevation and the bottom is lower than the bottom of the steel anchor pipe; S14, pouring capping concrete to the second preset elevation above the soil exposed by continuing to excavate 1.2m downward, and a plurality of air vents are preset in the capping concrete, and each air vent is connected to each mounting hole in a one-to-one correspondence; S15, connecting the grouting pipeline to the grouting pipe, and grouting toward the bottom of the mounting hole through the grouting pipe until the slurry overflows from the air hole.

[0018] Furthermore, a plurality of overflow holes are opened on the peripheral wall of the section of the steel anchor pipe located 1.2 m below the top of the mounting hole at intervals of 1 m along the length direction; each overflow hole is sealed by glass glue and / or tape; and after S15, it also includes: connecting the grouting pipeline to the top of the steel anchor pipe, and performing secondary grouting through the steel anchor pipe.

[0019] Furthermore, an I-beam or steel pipe is fixedly inserted inside the steel anchor pipe; when the steel pipe is fixedly inserted inside the steel anchor pipe, a plurality of threaded steel bars are fixedly connected to the outer peripheral wall of the steel pipe, and each of the threaded steel bars is evenly distributed along the circumference of the axis of the steel pipe.

[0020] Furthermore, after the anti-cracking structure is set up in the road section, it also includes: setting settlement observation piles and / or displacement observation piles in the road section; setting the settlement observation piles at least at one of the roadbed center and the hard shoulder edge line of the road section; setting the displacement observation piles at at least one of the lower roadbed side slope platform, the lower roadbed slope foot and the outer edge of the drainage ditch in the road section.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The method for treating cracks in the base layer of a steep transverse slope silt roadbed provided by the present disclosure provides a targeted anti-crack structure based on the different original transverse slope gradients and location environments of the crack-occurring sections, thereby preventing the recurrence of cracks in the base structure layer of that section. This method ensures crack prevention capabilities while limiting the cost of the anti-crack structure. 2. The method for treating cracks in the base layer of a steep slope silt roadbed provided by the present disclosure utilizes a unique elastic waterproofing structure to effectively prevent water from penetrating the elastic belt and entering the backwater side of the elastic belt. Furthermore, the telescopic tube structure has superior deformation capability (i.e., it can adapt to the pulling effect of increasing expansion joint width). 3. The method for treating cracks in the base of a steep slope silt roadbed provided by the embodiment of the present disclosure enhances the connection strength between the steel anchor pipe and the soil around the installation hole through primary grouting and secondary splitting grouting, thereby providing a strong bearing capacity foundation for the toe wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings: Figure 1 A schematic diagram of a road cross section of a road section where cracks occur drawn according to an embodiment of the present invention; Figure 2 A schematic diagram of construction for downward excavation of the road section drawn according to an embodiment of the present invention; Figure 3 A construction schematic diagram of excavating downward and then paving upward on the road section drawn according to an embodiment of the present invention; Figure 4 The anti-cracking structure is set on the road section according to the road data drawn according to the embodiment of the present invention. Figure 5 This is a schematic diagram showing that the water-blocking walls on both sides of the expansion joint are connected by elastic waterproof members according to an embodiment of the present invention; Figure 6 A longitudinal cross-sectional diagram of a grouting structure with grouting micropiles drawn according to an embodiment of the present invention; Figure 7 Based on Figure 6 Cross-sectional view of the grouting structure drawn along line AA; Figure 8 Based on Figure 6 Cross-sectional view of the grouting structure drawn along the middle BB line; Figure 9 Based on Figure 6 Cross-sectional view of the grouting structure drawn along the CC line.

[0023] Markings and corresponding parts names in the accompanying drawings: 11- road base structure layer; 111- upper base; 112- lower base; 113- subbase; 12- upper roadbed; 13- lower roadbed; 14- geogrid; 15- original ground; 16- drainage ditch; 21- water-retaining wall; 22- footing wall; 23- crushed soil and stone; 24- grouting micro pile; 31- expansion joint; 32- groove; 33- filler; 34- elastic belt; 341- expansion tube; 342- expansion tube; 343- water-permeable hole; 41- mounting hole; 42- steel anchor pipe; 43- grouting pipe; 44- bracket; 45- capping concrete; 46- centering frame; 47- lifting ring; 48- overflow hole; 49- steel pipe; 51- threaded steel bar; 52- settlement monitoring pile; 53- displacement monitoring pile. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the examples and accompanying drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention. It should be noted that the present invention is already in the actual development and use stage.

[0025] The "Code for Design of Building Foundations" (GB 5007-2011) defines "silt" as soil with particles larger than 0.075 mm accounting for no more than 50% of the total mass and a plasticity index (IP) of 10 or less. Silt lacks the advantages of sand, such as high permeability, easy drainage and consolidation, and high shear strength, nor the advantages of clay, such as good waterproofing, resistance to erosion, and high cohesion. Consequently, it exhibits poor mechanical properties in many engineering applications.

[0026] When building roads on silty soil, a certain thickness of surface soil is usually removed and compacted. Then, the soil is filled in layers with slag and vibrated and compacted layer by layer until the design elevation of the top of the roadbed is reached. After a one-year settlement period, the base structure layer (usually including the upper base, lower base and subbase) is constructed. However, after the construction of the base structure layer of such roads is completed, longitudinal cracks of varying degrees will still appear in the base structure layer during the rainy season.

[0027] Chinese invention patent CN202110510952.8 discloses a method for treating longitudinal cracks in soft rock roadbeds, which involves first excavating the soft rock roadbed to the bottom of the roadbed in the section where cracks appear, then laying geocells, and then backfilling with soft rock and soil fillers. The grouting pipe is passed through the grid holes of the geocells to perform grouting operations with a grouting depth greater than the depth of the roadbed diseased area. This method can not only reduce the impact of water on the soft rock roadbed, limit the development of longitudinal cracks in the roadbed, and reduce uneven settlement of the roadbed, but also overcome the non-persistence of the roadbed grouting reinforcement effect, thereby ensuring the long-term stable operation of the road. However, in essence, it is to form the soil into a whole, thereby preventing the occurrence of longitudinal cracks in the soft rock roadbed, ensuring the long-term stability of the reinforced soft rock roadbed, and reducing the risk of secondary diseases. For existing ground with steep transverse slopes of silt, in addition to the silt itself softening when exposed to water, which significantly reduces the bearing capacity and shear strength of the existing ground, leading to cracks in the road base structure built above it, the existing ground's transverse slope is also a major factor in inducing roadbed settlement and localized sideways sliding. Even if the silt is reinforced through the "laying geocells and grouting between the cell meshes" method, the silt is still prone to overall sideways sliding due to contact with water, which can lead to cracks in the base layer.

[0028] In order to repair sections of roads where cracks have occurred in the base structural layer and prevent recurrence of such cracks, thereby ensuring smooth subsequent pavement construction and reducing operation and maintenance costs during operation, the present invention provides a method for treating cracks in the base structural layer of steep transverse slope silt soil roadbed, which is intended to at least partially overcome the aforementioned technical problems and achieve the aforementioned beneficial effects.

[0029] Example 1: like Figures 1 to 3 As shown, this embodiment provides a method for treating cracks in a steep slope silt roadbed, the method comprising: Collect road data on sections where cracks occur; After completing the road data collection for this section, excavation and resurfacing repair work will be carried out on this section; After the excavation and resurfacing repair work of the road section is completed, an anti-cracking structure is set up on the road section according to the road data.

[0030] Specifically, the excavation and resurfacing repair work on the road section includes: Excavate downwards in this section, passing through the upper base 111, the lower base 112, the subbase 113 and the upper roadbed 12 in sequence, until the top surface of the lower roadbed 13 is exposed, and compact the exposed lower roadbed 13; The upper roadbed 12 material, the subbase 113 material, the lower base 112 material and the upper base 111 material are laid in sequence on the compacted lower roadbed 13 and compacted layer by layer.

[0031] During the downward excavation of this section, the excavation area was reduced layer by layer, forming steps between adjacent layers; Before laying the upper roadbed 12 material on the compacted lower roadbed 13, the process also includes laying a geogrid 14 on the top surface of the compacted lower roadbed 13; After the upper base layer 111 is laid and compacted, the geogrid 14 is laid on the compacted upper base layer 111. Preferably, the geogrid 14 laid on the upper surface of the compacted upper base layer 111 is a glass fiber grid.

[0032] It should be understood that the term "original cross slope" refers to the slope of the lower surface of the roadbed 13 (i.e., the original ground surface 15) below the cracked section, along the road width. When laying the upper roadbed 12, subbase 113, lower base 112, and upper base 111 materials, each layer is not laid all at once to the preset thickness. Instead, it is laid and compacted layer by layer according to the preset construction thickness until the preset thickness is reached. Accordingly, during the excavation of this section, steps are reserved within each layer according to the preset construction thickness.

[0033] Therefore, in this embodiment, during the downward excavation process, steps are left between each layer (see Figure 2 ), which can make the connection interface between the two adjacent layers of the road section and the unexcavated part of the corresponding elevation staggered in the vertical direction after repair (see Figure 3 ), thereby enhancing the integrity of the road section after repair; similarly, by reserving steps within each layer according to the preset construction thickness during the downward excavation process (such as Figure 2 , schematically showing the steps formed in the upper roadbed 12 when the upper roadbed 12 is excavated downwards), which can make the connection interfaces between the two adjacent construction paving layers of the road section and the unexcavated parts of the corresponding elevation staggered in the vertical direction after repair (such as Figure 3 The figure schematically shows a situation in which the connection interfaces of two adjacent construction paving layers of the upper roadbed 12 and the unexcavated parts at the corresponding elevations are staggered in the vertical direction during the repair phase), thereby enhancing the integrity of the various layers of the road section after repair; by laying geogrids 14 on the top surface of the compacted lower roadbed 13, the connection strength between the connection interface of the lower roadbed 13 and the upper roadbed 12 can be enhanced; by laying fiberglass grids on the compacted upper base layer 111, the connection strength between the upper base layer 111 and the subsequently constructed asphalt pavement can be enhanced; all of the above designs are conducive to preventing the re-appearance of cracks in the road section after repair.

[0034] Example 2: like Figure 4 As shown, this embodiment is based on embodiment 1, except that, in this embodiment: The road data includes original cross slope gradient and location environment; When the original cross slope is less than 1:5, setting the anti-cracking structure on the road section according to the road data includes: Excavate downwards to a first preset elevation outside the drainage ditch 16 of the road section, and build a water-blocking wall 21 above the soil exposed after the excavation; In a case where the original cross slope is less than 1:5 and the road section is located in a valley, setting an anti-cracking structure on the road section according to the road data further includes: Excavate downwards to a second preset elevation on the lower side of the original ground of the road section, build a retaining wall 22 above the soil exposed after excavation, and fill crushed soil and stone 23 between the retaining wall 22 and the lower roadbed 13; When the original cross slope is greater than 1:5, the step of setting the anti-cracking structure on the road section according to the road data further includes: Before setting up the retaining wall 22, a plurality of grouting micropiles 24 are set under the soil exposed after excavation downward to the second preset elevation, and then the retaining wall 22 is set above the grouting micropiles 24, and the upper part of each grouting micropiles 24 is fixedly connected to the retaining wall 22.

[0035] It should be understood that the term "location environment" mainly refers to the terrain where the road section is located, such as the "valley" mentioned above.

[0036] Accordingly, this embodiment provides a targeted anti-cracking structure based on the different original cross slopes and location environments of the road section where cracks occur, thereby preventing the recurrence of cracks in the base structure layer of the road section. Specifically, by setting up a water-retaining wall 21, it is possible to effectively prevent water from flowing from a high place (the higher side of the original ground of the road section) from invading the silt below the road section, thereby fundamentally solving the problem that the bearing capacity and shear strength of the original ground 15 of the road section are greatly reduced due to the softening of the silt by water, which in turn causes cracks in the base structure layer 11 of the road built above it; and for the valley, in addition to being easily invaded by water from the higher side of the original ground of the road section, it is also easily covered and infiltrated by the seasonal runoff that often occurs in the valley, which increases the deadweight of the road section, and thus increases the sliding force, making the lower side of the original ground of the road section prone to local settlement and side sliding. For this reason, in addition to setting up a water-retaining wall, this embodiment also provides a water-retaining wall 21. In addition to the wall 21, a retaining wall 22 is provided and crushed soil and stone 23 is filled between the retaining wall 22 and the lower roadbed 13 to form a counter pressure on the lower roadbed 13, thereby resisting the downward force and downward movement trend of the road section; and when the original cross slope is greater than 1:5, the main cause of cracks in the base structure layer of the road section is the excessive downward force caused by the large slope. For this reason, in addition to providing the water-retaining wall 21 and the retaining wall 22, this embodiment also provides a plurality of grouting micro-piles 24 under the retaining wall 22. The grouting micro-piles 24 are used to enhance the shear resistance of the retaining wall 22 (essentially, to enhance its ability to resist the downward force of the road section) and enhance the bearing capacity of the foundation at the bottom of the retaining wall 22.

[0037] Example 3: like Figure 5 As shown, this embodiment is based on embodiment 2, except that, in this embodiment: The first preset elevation is at least 2m lower than the higher side of the original ground; A first impermeable membrane is laid on the bottom surface of the water-blocking wall 21 and on the side facing the drainage ditch 16. The first impermeable membrane overlaps with the second impermeable membrane laid on the bottom of the drainage ditch 16, and the overlap width is greater than 0.5m; When the length of the water-blocking wall 21 is between 4 and 8 meters, an expansion joint 31 is provided at the midpoint of the water-blocking wall 21 along the length direction; when the length of the water-blocking wall 21 is greater than 8 meters, an expansion joint 31 is provided at every 4 meters along the length direction of the water-blocking wall 21; the water-blocking walls 21 on both sides of the expansion joint 31 are connected by elastic waterproof parts.

[0038] Specifically, vertical grooves 32 are provided on the facing surfaces of the water-blocking walls 21 on both sides of the expansion joint 31; the elastic waterproof member includes a filler 33 and an elastic belt 34; The elastic belt 34 includes a telescopic tube 341 arranged along the length direction of the belt, and expansion tubes 342 arranged on both sides of the telescopic tube 341; A plurality of water-permeable holes 343 are provided on the wall of the expansion tube 342 , and each of the water-permeable holes 343 is located on the same side of the elastic belt 34 in the thickness direction. The expansion tube 342 is filled with the filler 33 ; When the water-blocking walls 21 on both sides of the expansion joint 31 are connected through the elastic waterproof part, the elastic belt 34 is inserted into the grooves 32 on both sides of the expansion joint 31 along the width direction and the water-permeable holes 343 face the water-facing surface of the water-blocking wall 21; the telescopic tube 341 is located in the expansion joint 31.

[0039] The working principle of the waterproof connector is as follows: when the water-facing surface of the water-blocking wall 21 encounters water, the water comes into contact with the elastic belt 34 through the expansion joint 31, and then the water comes into contact with the filler 33 through the water-permeable hole 343. Then the filler 33 absorbs water and expands, and pushes the tube wall of the expansion tube 342 to the wall surface of the groove 32 (especially the wall surface of the backwater side of the expansion tube 342), thereby effectively preventing the water from passing through the elastic belt 34 and entering the backwater side of the elastic belt 34. In addition, the setting of the expansion tube 341 utilizes the tubular structure to buffer the spacing changes of the expansion joint 31. Compared with relying solely on the expansion and contraction properties of the material itself to buffer the spacing changes of the expansion joint 31, its ability to adapt to distance changes is stronger.

[0040] It should be understood that the first and second impermeable membranes can be selected from commonly used impermeable membranes in the civil engineering industry. This is prior art and will not be further described. The first impermeable membrane can also be applied to the bottom and top surfaces of the water barrier 21, as well as the side facing away from the drainage ditch 16, or even to the outer surface of the water barrier 21. The number of expansion tubes 342 provided on one side of the telescopic tube 341 can be one or more. Preferably, the cross-sectional profile of the groove 32 conforms to the outer cross-sectional profile of the expansion tube 342.

[0041] Accordingly, when water intrudes onto the water-facing surface of the water barrier 21, the water barrier 21 + first impermeable membrane structure provides water-blocking capabilities, achieving an overall water-blocking effect. Localized water-blocking at the expansion joint 31 is achieved through the installation of elastic waterproof members, thereby preventing water from intruding into the silt beneath the road section from the higher side of the original ground. Furthermore, the first preset elevation being at least 2 meters below the higher side of the original ground helps prevent water from intruding into the silt beneath the road section through the bottom of the water barrier 21. The overlap width of the first and second impermeable membranes, which is greater than 0.5 meters, effectively prevents water leakage from the overlap joint.

[0042] Preferably, the elastic belt 34 is selected from one or more of EPDM rubber, silicone rubber, nitrile rubber, polyurethane elastomer, fluororubber and soft PVC; The filler 33 is selected from one or more of bentonite, super absorbent resin and PVA-PEG cross-linked gel particles.

[0043] A permeable cushioning layer (not shown) is attached to the inner wall of the expansion tube 342. The permeable cushioning layer is selected from one or more of a PTFE microporous membrane, a nylon 66 microporous membrane, a PP microporous membrane, and a non-woven fabric. This permeable cushioning layer effectively prevents the swollen filler 33 from overflowing through the permeable holes 343, thereby ensuring the elastic waterproof member operates efficiently over multiple cycles.

[0044] Example 4: Please continue to refer to Figure 1 This embodiment is based on embodiment 2, except that: The second preset elevation is at least 2m lower than the lower side of the original ground; The crushed soil and rocks 23 filled between the retaining wall 22 and the lower roadbed 13 are spread and compacted in layers, with a compaction degree greater than 96%, until the crushed soil and rocks 23 are flush with the top of the retaining wall 22.

[0045] Accordingly, the footing wall 22 can fully resist the sliding force and creep of the road section, thereby preventing the base structure layer from cracking due to the sliding of the road section.

[0046] More preferably, the road data further includes the direction of the cracks in the road section, and the length direction of the footing wall 22 is parallel to the direction of the cracks in the road section.

[0047] Accordingly, the wall surface of the footing wall 22 is perpendicular to the downward force of the road section, which can improve the effect of the footing wall 22 in resisting the downward movement of the road section and prevent the road section from sliding sideways along the wall surface of the footing wall 22.

[0048] Example 5: This embodiment is based on embodiment 2, except that: The retaining wall 22 and the water-blocking wall 21 are both concrete walls, and a steel cage (not shown in the figure) is provided in the retaining wall 22 and the water-blocking wall 21; In the case where both the footing wall 22 and the water-blocking wall 21 are provided on this road section, the steel cage in the footing wall 22 and the steel cage in the water-blocking wall 21 are connected by tie bars (not shown in the figure); The tie bars are selected from one or more of threaded steel bars and steel cables.

[0049] It should be understood that the tie bars were pre-embedded during the resurfacing of the repaired road section. Accordingly, the ends of the tie bars were connected to the corresponding steel cages during the construction of the footing wall 22 and the watertight wall 21. Obviously, the tie bars are rust-resistant. Preferably, the cast concrete wall is C30 concrete.

[0050] Accordingly, by providing the reinforcement bars, the ability of the footing wall 22 to resist the downward force of the road section can be improved, and the integrity of the anti-cracking structure is also improved.

[0051] Example 6: like Figures 6 to 9 As shown, this embodiment is based on embodiment 2, except that, in this example: The method of setting a plurality of grouting micro piles 24 below the soil exposed after excavating downward to the second preset elevation includes: S11, after excavating downward to the second preset elevation, continue excavating downward for 1.2 m and compact the exposed soil; S12, determining the installation points of the grouting micro piles 24 on the compacted soil surface, drilling down to a preset depth at each point and cleaning the hole to obtain the installation hole 41; S13, inserting a steel anchor pipe 42 and a grouting pipe 43 into the mounting hole 41; the bottom end of the steel anchor pipe 42 is closed and the top end is open, and a bracket 44 is fixedly connected below the steel anchor pipe 42, and the top end of the steel anchor pipe 42 is flush with the second preset elevation; the top end of the grouting pipe 43 is higher than the second preset elevation and the bottom end is lower than the bottom end of the steel anchor pipe 42; S14, pouring capping concrete 45 to the second preset elevation above the soil exposed by further excavation 1.2 m downward. A plurality of vent holes (not shown) are preset in the capping concrete 45, and each vent hole is connected to each mounting hole 41 in a one-to-one correspondence. S15, connecting the grouting pipe 43 to the grouting pipe 43, and injecting grout toward the bottom of the installation hole 41 through the grouting pipe 43 (one-time grouting) until the slurry overflows from the vent hole.

[0052] Preferably, the grouting micropiles 24 are arranged in a plum blossom shape with a horizontal and vertical spacing of 1 m; the slurry mixture ratio of the slurry injected through the grouting pipe 43 is cement: water = 1:0.45-0.5, and the grouting pressure is 0.3MPa-0.5Mpa.

[0053] Preferably, a pair of centering brackets 46 are fixedly installed every 3 meters along the length of the outer wall of the steel anchor pipe 42. This ensures that the steel anchor pipe 42 is installed centered in the mounting hole 41, and further ensures that the grout injected into the bottom of the mounting hole 41 through the grouting pipe 43 is evenly coated on the outer periphery of the steel anchor pipe 42 to form a uniform protective layer.

[0054] Preferably, a plurality of lifting rings are welded on the outer peripheral wall of the upper portion of the steel anchor pipe 42 , and the lifting rings are evenly distributed around the circumference. The lifting rings can facilitate the lifting and installation of the steel anchor pipe 42 .

[0055] It should be understood that the drilling of the installation hole 41 can be carried out using a down-the-hole drill. If the drilling process encounters situations such as gravel that are difficult to form a hole and low hole-forming efficiency, it can be changed to a follow-up grouting process to reduce the disturbance to the stratum and the probability of hole collapse, thereby improving the hole-forming efficiency. The cleaning of the installation hole 41 can be achieved using a high-pressure airflow. This part is the existing technology and will not be described in detail. Obviously, the bottom end of the grouting pipe 43 should be lower than the bottom end of the steel anchor pipe 42 and higher than the bottom end of the bracket 44, so that the slurry can be smoothly injected into the installation hole 41. The bracket 44 connected to the bottom of the steel anchor pipe 42 can support the steel anchor pipe 42 and also provide an appropriate slurry outlet space for the end of the grouting pipe 43. During the process of grouting toward the bottom of the installation hole 41 through the grouting pipe 43, when the stratum absorbs a large amount of grout or the slurry is lost, limited grouting, intermittent grouting, repeated grouting or grouting can be controlled by adjusting the slurry ratio and changing the grouting material, adding accelerators, bentonite, etc., and the grouting method is more flexible and controllable.

[0056] Accordingly, by injecting grout toward the bottom of the mounting hole 41 through the grouting pipe 43, the larger cracks in the mounting hole 41 can be sealed, the density and shear strength of the soil around the mounting hole 41 can be improved, and the conditions for forming a "splitting" effect for subsequent secondary grouting can be created.

[0057] More preferably, a plurality of overflow holes 48 are provided on the peripheral wall of the steel anchor pipe 42 located 1.2 m below the top end of the mounting hole 41 at intervals of 1 m along the longitudinal direction (i.e., a circle of overflow holes 48 is provided every 1 m, and a plurality of overflow holes 48 are evenly distributed around the circumference of the circle); each of the overflow holes 48 is sealed with glass glue and / or tape; The S15 further includes: The grouting pipe 43 is connected to the top end of the steel anchor pipe 42 , and secondary grouting is performed through the steel anchor pipe 42 .

[0058] Furthermore, an I-beam or steel pipe 49 is fixedly inserted inside the steel anchor pipe 42; When the steel pipe 49 is fixedly inserted into the steel anchor pipe 42 , a plurality of threaded steel bars 51 are fixedly connected to the outer peripheral wall of the steel pipe 49 . The threaded steel bars 51 are evenly distributed along the circumference of the axis of the steel pipe 49 .

[0059] Preferably, secondary grouting is performed when the axial compressive strength of the grouting body is not less than 1 MPa 5 to 12 hours after the completion of the primary grouting. The slurry mix ratio of the secondary grouting is cement: water = 1:0.7, and the grouting pressure is 1 MPa to 5 MPa.

[0060] As a result, the secondary grouting performed under high pressure can flow out through the overflow hole 48 , thereby splitting the cement stone body of the primary grouting and spreading it to the surroundings, thereby reinforcing the rock and soil body around the installation hole 41 .

[0061] Through the primary grouting and the secondary grouting, a grouting micro pile 24 tightly integrated with the rock and soil around the installation hole 41 can be formed, thereby providing a foundation with strong bearing capacity for the footing wall 22 .

[0062] In this embodiment, the capping concrete 45 can block the surrounding ground, thereby preventing the slurry from the primary grouting and the secondary grouting from seeping upward along the stratum fissures around the steel anchor pipe 42 or even overflowing from the ground.

[0063] In a specific practice of this embodiment, the steel anchor pipe 42 is formed by connecting multiple φ108×6mm hot-rolled seamless steel pipes. Two adjacent hot-rolled seamless steel pipes are connected by a joint steel pipe sleeve on the outside of the connection and welded to achieve a sealed connection; the lifting ring welded on the steel anchor pipe 42 is a nut; the bottom end of the steel anchor pipe 42 is sealed by welding a bottom steel plate with a thickness of 50mm and the same outer diameter as the φ108×6mm hot-rolled seamless steel pipe; the grouting pipe 43 is a φ22mm PVC pipe and is arranged on the outside of the steel anchor pipe 42 (it can also be set On the inside of the steel anchor pipe 42, but it needs to penetrate the bottom end of the steel anchor pipe 42 and pay attention to the sealing of the penetration part); the size of the overflow hole 48 is φ8mm, and the overflow holes 48 of two adjacent overflow holes 48 rings are staggered; a φ42×4mm steel pipe 49 equal to the length of the steel anchor pipe 42 is inserted inside the steel anchor pipe 42, and four φ22mm threaded steel bars 51 are welded to the outer peripheral wall of the steel pipe 49; the slurry mix ratio of the slurry injected through the grouting pipe 43 is cement: water = 1:0.5, and the grouting pressure is 0.5MPa; the grouting pressure of the secondary grouting is 4MPa.

[0064] Example 7: Please continue to refer to Figure 1 This embodiment is based on embodiment 1, except that: After the anti-cracking structure is set up on this section of road, it also includes: Set up settlement observation piles and / or displacement observation piles on this road section; The settlement observation pile is set at least at one location in the roadbed center and the hard shoulder edge of the road section; The displacement observation pile is set at at least one of the slope platform of the lower roadbed 13, the slope foot of the lower roadbed 13 and the outer edge of the drainage ditch 16 of the road section.

[0065] Therefore, by conducting continuous observation after repairing the road section, settlement and displacement can be discovered in time, and early prevention can be taken to avoid causing other secondary accidents.

[0066] It should be understood that the method for treating cracks in the base layer of a steep slope silt roadbed provided by the embodiment of the present invention is also applicable to the prevention and control of longitudinal cracks on the top of the soft soil roadbed, the top of the pavement base layer, and the top of the asphalt pavement.

[0067] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for treating cracks in the base of a steep slope silt roadbed, characterized in that: include: Collect road data on sections where cracks occur; After completing the road data collection for this section, excavation and resurfacing repair work will be carried out on this section; After the excavation and resurfacing repair work of the road section is completed, an anti-cracking structure is set up on the road section according to the road data.

2. The method for treating cracks in the base of a steep slope silt roadbed according to claim 1, wherein: The excavation and resurfacing repair work on the road section includes: Excavating downwards in the road section, sequentially passing through the upper base (111), the lower base (112), the subbase (113) and the upper roadbed (12), until the top surface of the lower roadbed (13) is exposed, and compacting the exposed lower roadbed (13); The upper roadbed (12) material, the subbase (113) material, the lower base (112) material and the upper base (111) material are laid in sequence on the compacted lower roadbed (13) and compacted layer by layer.

3. The method for treating cracks in the base of a steep slope silt roadbed according to claim 2, wherein: During the downward excavation of this section, the excavation area was reduced layer by layer, forming steps between adjacent layers; Before laying the upper roadbed (12) material on the compacted lower roadbed (13), the method further includes laying a geogrid (14) on the top surface of the compacted lower roadbed (13); After the upper base layer (111) material is laid and compacted, the method further includes laying a geogrid (14) on top of the compacted upper base layer (111).

4. The method for treating cracks in the base of a steep slope silt roadbed according to claim 1, wherein: The road data includes original cross slope gradient and location environment; When the original cross slope is less than 1:5, setting the anti-cracking structure on the road section according to the road data includes: Excavating downwards to a first preset elevation outside the drainage ditch (16) of the road section, and constructing a water-retaining wall (21) above the soil exposed after the excavation; In a case where the original cross slope is less than 1:5 and the road section is located in a valley, setting an anti-cracking structure on the road section according to the road data further includes: Excavating downward to a second preset elevation on the lower side of the original ground of the road section, building a retaining wall (22) above the soil exposed after the excavation, and filling crushed soil and stone (23) between the retaining wall (22) and the lower roadbed (13); When the original cross slope is greater than 1:5, the step of setting the anti-cracking structure on the road section according to the road data further includes: Before setting the retaining wall (22), a plurality of grouting micro piles (24) are set below the soil exposed after excavation downward to a second preset elevation, and then the retaining wall (22) is set above the grouting micro piles (24), and the upper part of each grouting micro pile (24) is fixedly connected to the retaining wall (22).

5. The method for treating cracks in the base of a steep slope silt roadbed according to claim 4, characterized in that: The first preset elevation is at least 2m lower than the higher side of the original ground; A first impermeable membrane is laid on the bottom surface of the water-blocking wall (21) and on the side facing the drainage ditch (16), and the first impermeable membrane overlaps with a second impermeable membrane laid on the bottom of the drainage ditch (16), and the overlap width is greater than 0.5m; When the length of the water-blocking wall (21) is between 4 and 8 meters, an expansion joint (31) is provided at the midpoint of the water-blocking wall (21) along the length direction; when the length of the water-blocking wall (21) is greater than 8 meters, an expansion joint (31) is provided at intervals of 4 meters along the length direction of the water-blocking wall (21); the water-blocking walls (21) on both sides of the expansion joint (31) are connected by elastic waterproof parts.

6. The method for treating cracks in the base of a steep slope silt roadbed according to claim 5, characterized in that: Vertical grooves (32) are provided on the facing surfaces of the water-blocking walls (21) on both sides of the expansion joint (31); the elastic waterproof member includes a filler (33) and an elastic belt (34); The elastic belt (34) comprises a telescopic tube (341) arranged along the length direction of the belt, and expansion tubes (342) arranged on both sides of the telescopic tube (341); A plurality of water-permeable holes (343) are provided on the wall of the expansion tube (342), each of the water-permeable holes (343) being located on the same side of the elastic belt (34) in the thickness direction, and the expansion tube (342) is filled with the filler (33); When the water-blocking walls (21) on both sides of the expansion joint (31) are connected via the elastic waterproof member, the elastic belt (34) is inserted into the grooves (32) on both sides of the expansion joint (31) along the width direction, and the water-permeable holes (343) face the water-facing surface of the water-blocking wall (21); the expansion pipe (341) is located in the expansion joint (31).

7. The method for treating cracks in the base of a steep slope silt roadbed according to claim 6, characterized in that: The elastic belt (34) is selected from one or more of EPDM rubber, silicone rubber, nitrile rubber, polyurethane elastomer, fluororubber and soft PVC; The filler (33) is selected from one or more of bentonite, super absorbent resin and PVA-PEG cross-linked gel particles.

8. The method for treating cracks in the base of a steep slope silt roadbed according to claim 6, wherein: A water-permeable cushion layer is attached to the inner wall of the expansion tube (342), and the water-permeable cushion layer is selected from one or more of PTFE microporous membrane, nylon 66 microporous membrane, PP microporous membrane and non-woven fabric.

9. The method for treating cracks in the base of a steep slope silt roadbed according to claim 4, wherein: The second preset elevation is at least 2m lower than the lower side of the original ground; The crushed soil and stone (23) between the retaining wall (22) and the lower roadbed (13) is spread and rolled in layers, with a compaction degree greater than 96%, until the crushed soil and stone (23) is flush with the top of the retaining wall (22).

10. The method for treating cracks in the base of a steep slope silt roadbed according to claim 4, characterized in that: The road data also includes the direction of the cracks in the road section, and the length direction of the footing wall (22) is parallel to the direction of the cracks in the road section.

11. The method for treating cracks in the base of a steep slope silt roadbed according to claim 4, characterized in that: The footing wall (22) and the water-blocking wall (21) are both concrete-cast walls, and steel cages are provided in the footing wall (22) and the water-blocking wall (21); In the case where both a footing wall (22) and a water-blocking wall (21) are provided on the road section, the steel cage in the footing wall (22) and the steel cage in the water-blocking wall (21) are connected by tie bars; The tie bars are selected from one or more of threaded steel bars and steel cables.

12. The method for treating cracks in the base of a steep slope silt roadbed according to claim 4, characterized in that: The method of setting a plurality of grouting micro piles (24) below the soil exposed after excavation downward to the second preset elevation comprises: S11, after excavating downward to the second preset elevation, continue excavating downward for 1.2 m and compact the exposed soil; S12, determining the location of the grouting micro piles (24) on the compacted soil surface, drilling down to a preset depth at each location and cleaning the hole to obtain an installation hole (41); S13, inserting a steel anchor pipe (42) and a grouting pipe (43) into the mounting hole (41); the bottom end of the steel anchor pipe (42) is closed and the top end is open, a bracket (44) is fixedly connected below the steel anchor pipe (42), and the top end of the steel anchor pipe (42) is flush with the second preset elevation; the top end of the grouting pipe (43) is higher than the second preset elevation and the bottom end is lower than the bottom end of the steel anchor pipe (42); S14, pouring capping concrete (45) to the second preset elevation above the soil exposed by continuing to excavate downward for 1.2 m, wherein a plurality of vent holes are preset in the capping concrete (45), and each vent hole is connected to each mounting hole (41) in a one-to-one correspondence; S15, connecting the grouting pipe (43) to the grouting pipe (43), and injecting grout toward the bottom of the mounting hole (41) through the grouting pipe (43) until the slurry overflows from the vent hole.

13. The method for treating cracks in the base of a steep slope silt roadbed according to claim 12, wherein: A plurality of overflow holes (48) are provided on the peripheral wall of the steel anchor pipe (42) located 1.2 m below the top end of the mounting hole (41) at intervals of 1 m along the longitudinal direction; each overflow hole (48) is sealed with glass glue and / or adhesive tape; The S15 further includes: The grouting pipe (43) is connected to the top end of the steel anchor pipe (42), and secondary grouting is performed through the steel anchor pipe (42).

14. The method for treating cracks in the base of a steep slope silt roadbed according to claim 12, wherein: An I-beam or a steel pipe (49) is fixedly inserted inside the steel anchor pipe (42); When a steel pipe (49) is fixedly inserted inside the steel anchor pipe (42), a plurality of threaded steel bars (51) are fixedly connected to the outer peripheral wall of the steel pipe (49), and the threaded steel bars (51) are evenly distributed along the circumference of the axis of the steel pipe (49).

15. The method for treating cracks in the base of a steep slope silt roadbed according to claim 1, characterized in that: After the anti-cracking structure is set up on this road section, it also includes: Set up settlement observation piles and / or displacement observation piles on this road section; The settlement observation pile is set at least at one location in the roadbed center and the hard shoulder edge of the road section; The displacement observation pile is provided at least one of the lower roadbed (13) side slope platform, the lower roadbed (13) slope foot, and the outer edge of the drainage ditch (16) of the road section.

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