Construction method and settlement treatment method of rock slope overhanging road structure

Abstract

The application discloses a rock slope overhanging type road structure construction method and settlement treatment method, relates to the field of road engineering, and aims to improve the stress of a road structure and make the road structure more economical and reasonable. The technical scheme is as follows: the rock slope overhanging type road structure construction method comprises the following steps: excavating a heap to form a base of an outer retaining wall foundation; constructing the outer retaining wall foundation on the base; constructing the outer retaining wall on the upper portion of the outer retaining wall foundation; backfilling on the inner side of the outer retaining wall to form a backfilled roadbed; constructing an anchoring member in the bedrock roadbed on the inner side of the backfilled roadbed; and constructing a road panel on the upper portions of the backfilled roadbed and the bedrock roadbed, with the upper end of the anchoring member being connected with the road panel. The rock slope overhanging type road structure settlement treatment method is characterized in that the road panel is provided with a grouting hole, and when the backfilled roadbed appears settlement, grouting is performed through the grouting hole. The application is used for the design, construction and maintenance of roads on rock slopes.

Description

Technical Field

[0001] This invention relates to the field of road engineering, specifically to a road structure for constructing roads on rocky slopes, wherein part of the roadbed of the open section is bedrock on the mountainside and part of the roadbed is a cover layer and fill, as well as a method for constructing the road structure and a method for treating settlement of the road structure. Background Technology

[0002] Hydropower stations are often built in high mountain and canyon areas with rugged terrain, steep slopes, deep valleys, and sparse population. To establish transportation links with the outside world, roads must first be constructed. In canyon road construction, open sections often use a combination of excavation and filling on natural slopes. In some sections, the mountainside half of the roadbed is bedrock, while the gully or riverside half consists of a thick overburden layer and fill. The overburden and fill are loose deposits; after a year of natural settlement, the slope can generally reach a self-stabilized state. After 3-5 years of natural settlement, the slope can generally reach a stable state, but the construction schedule and usage requirements do not allow for waiting 3-5 years before road construction.

[0003] Roads cannot be directly constructed over unstable or suspended fill. To ensure road safety and accommodate the settlement and deformation of the fill, certain engineering measures are required before road construction. There are three methods for constructing an outer retaining wall on top of a partially suspended, thick overburden layer or fill: Method 1: Excavate to the bedrock surface, construct anchor bolts on the bedrock surface, pour concrete uphill to form an enlarged foundation for the retaining wall, and then construct a counterweight retaining wall on the enlarged foundation. Backfill the inside of the wall to form the roadbed and pavement. Method 2: Construct pile foundation beams on top of the fill, then construct a counterweight retaining wall on the pile foundation beams. Backfill the inside of the counterweight retaining wall to form the roadbed. Method 3: When the span is small, use a half-arch bridge to cross over the fill before forming the pavement. For Method 1, the retaining wall excavation depth is very deep, posing potential safety risks and adverse conditions such as slope collapse, falls from height, and road closures during the excavation process. Using large construction machinery such as excavators in conjunction with manual labor results in limited construction space, working near edges, high safety risks, and inconvenience. Constructing foundations on strongly unloaded rock slopes carries the risk of overall retaining wall collapse and overturning due to unstable foundations. Method 1 is difficult to construct, carries high safety risks, has a long construction period, and requires a large amount of concrete, making it uneconomical. Method 2, bored pile construction, also has high safety risks, a long construction period, and high costs. Method 3 is not suitable for large spans or when the bridge foundations at both ends do not meet requirements; it also suffers from long construction periods, high costs, and is uneconomical. Summary of the Invention

[0004] This invention first provides a cantilevered road structure for rock slopes, with the aim of improving the stress distribution of the road structure and making the road structure more economical and rational.

[0005] The technical solution adopted in this invention is: a cantilevered road structure on a rock slope, including an outer retaining wall and a road panel. The bottom of the outer retaining wall is the outer retaining wall foundation, the inner side of the outer retaining wall is the backfill roadbed, the side of the backfill roadbed facing away from the outer retaining wall is the bedrock roadbed, the upper part of the backfill roadbed and the bedrock roadbed is the road panel, and anchors are installed in the bedrock roadbed, with the upper end of the anchors connected to the road panel.

[0006] Since the retaining wall and backfilled roadbed generally settle, grouting is used to treat the settlement. Furthermore, grouting holes are installed at the points where the road slab meets the backfilled roadbed. To prevent rainwater from flowing into the backfilled roadbed through the grouting holes, temporary sealing materials are installed inside the grouting holes. For example, the temporary sealing materials are made of clay.

[0007] To reduce the height of the retaining wall and thus decrease excavation and masonry work, the retaining wall foundation further comprises: a consolidated body formed by grouting anchors into the slab, a cushion layer laid on top of the consolidated body, and an enlarged foundation laid on top of the cushion layer. The upper ends of the grouting anchors are located within the enlarged foundation, and the retaining wall is situated on top of the enlarged foundation. For example, the length of the grouting anchors is 3–4 m, and 2–3 rows of grouting anchors are arranged longitudinally along the road. The grouting anchors are self-drilling hollow grouting anchors, model A25 or A32.

[0008] To effectively drain water from the backfilled roadbed, further measures are taken: drainage holes are installed in the outer retaining wall, and a filter layer is installed on the inner side of the outer retaining wall in the backfilled roadbed. The drainage holes are evenly distributed on the outer retaining wall and slope outwards.

[0009] To further improve the self-stability of the outer retaining wall, it is further designed as a counterweight retaining wall.

[0010] Specifically: The road slab is a reinforced concrete structure. The reinforcement of the road slab includes transverse reinforcement, longitudinal reinforcement, and stirrups. Both transverse and longitudinal reinforcement are arranged in double layers. The upper end of the anchor is connected to the reinforcement of the road slab. The anchors are anchor rods or anchor cables, for example, cement mortar anchor rods of type C22 or C25, with a length of 3-4m. Multiple anchors are used and evenly distributed; for example, at least two rows of anchors are set along the longitudinal direction of the road. Based on the stress on the anchors, they are preferably arranged vertically.

[0011] To accommodate uneven settlement of the retaining wall foundation, further measures are taken: settlement joints are installed at intervals in the retaining wall, and the transverse joints between adjacent road panels are settlement joints that correspond to the settlement joints in the retaining wall. For example, settlement joints are installed at intervals of 6-8m in the retaining wall, and the length of a single road panel is also 6-8m.

[0012] Based on the stress and allowable deformation of the road slab, further details are as follows: The road slab does not have longitudinal joints along the road direction; the portion of the road slab located in the backfilled subgrade has at least one transverse joint; the portion of the road slab located in the bedrock subgrade has no transverse joints. Specifically, both the transverse joints and the transverse joints between the road slabs are dummy joints without dowel bars.

[0013] The beneficial effects of this invention's cantilevered road structure on rock slopes are as follows: Based on a thorough understanding of the mechanical properties of backfill and bedrock subgrades, and considering the road's intended function, this invention does not use the bearing capacity of the foundation as the controlling indicator for the bearing capacity of the retaining wall foundation. Instead, it fully utilizes the bearing capacity of the bedrock subgrade, proposing a cantilevered road structure similar to piano keys. This allows for some elastic deformation of the road panel without causing destructive deformation. This reduces the height of the retaining wall and the amount of masonry work, improves the convenience and operability of construction, reduces construction safety risks, accelerates construction progress, saves investment, and meets the requirements of practical highway functionality. Grouting holes are pre-reserved in the road panel corresponding to parts of the backfill subgrade. When settlement occurs on the side where the backfill subgrade is located, grouting can be performed through these holes to reinforce the backfill subgrade through grouting backfilling, ensuring the road remains unobstructed.

[0014] This invention also provides a method for constructing a cantilevered road structure on a rock slope, thereby constructing the aforementioned cantilevered road structure on a rock slope. The purpose is also to improve the stress distribution of the road structure, making it more economical and rational. The technical solution adopted is: a method for constructing a cantilevered road structure on a rock slope, comprising the following steps:

[0015] S1. Excavate the sludge to form the base of the external retaining wall foundation.

[0016] S2. Construct the outer retaining wall foundation on the base. The outer retaining wall foundation is used to support the outer retaining wall. The following is a method for obtaining the outer retaining wall foundation by grouting, including S2.1 to S2.3.

[0017] S2.1 Grouting anchors are installed on the base and grouting is performed, with exposed sections reserved for the grouting anchors.

[0018] S2.2 Construct and level the subbase. The thickness of the subbase is generally 10-20cm. Fine aggregate concrete with high slump and good workability, such as C20 fine aggregate concrete, can be used. The subbase serves to level and further fill and grout the joints.

[0019] S2.3 Construct an enlarged foundation on top of the foundation slab. The width of the enlarged foundation is determined based on the bottom width of the outer retaining wall, generally by extending it by 50cm to 100cm on both the inner and outer sides of the retaining wall. The width of the enlarged foundation is generally 2 to 4 meters. To accommodate uneven settlement, the enlarged foundation is reinforced with joints at the settlement joints of the outer retaining wall. The exposed section of the grouting anchor is located within the enlarged foundation, ensuring an effective connection between the grouting anchor and the enlarged foundation.

[0020] S3. Construct the outer retaining wall on top of the foundation. The outer retaining wall is preferably a counterweight retaining wall to improve its self-stability. Settlement joints are provided at intervals along the outer retaining wall, for example, in 6-8m sections, meaning each section of the outer retaining wall is 6-8m long. The outer retaining wall is cast in place, for example, using C20 concrete, with a wall height of 2-5m. To facilitate drainage of the backfilled roadbed inside the outer retaining wall, at least one drainage hole is also provided. The drainage hole is angled outwards to facilitate drainage and can be created by pre-embedding pipes before the outer retaining wall is poured.

[0021] S4. Backfilling is carried out on the inside of the outer retaining wall to form a backfill roadbed. Backfilling should be done in layers and compacted to reduce settlement. A filter layer is installed on the inside of the outer retaining wall in the backfill roadbed, and the filter layer corresponds to the drainage holes of the outer retaining wall to effectively drain accumulated water.

[0022] S5. Install anchors within the bedrock subgrade on the inner side of the backfilled subgrade. Anchors are primarily used to anchor the road slab and also reinforce the bedrock subgrade; anchor rods or anchor cables can be used. Multiple anchors are required, preferably evenly arranged in rows and columns. Based on the stress on the anchors, they are best arranged vertically. Exposed sections are provided for the anchors to connect to the road slab.

[0023] S6. Construct road panels on the upper part of backfilled roadbed and bedrock roadbed, with the upper end of the anchors connected to the road panels.

[0024] Road slabs are rigid structures, typically made of reinforced concrete. The thickness, concrete strength, and reinforcement of the road slab are determined based on a comprehensive calculation of the highway grade, pavement width, and vehicle load. For example, based on the stress on the road slab, the reinforcement includes transverse reinforcement, longitudinal reinforcement, and stirrups. Both transverse and longitudinal reinforcement are arranged in double layers. The upper end of the anchors is connected to the reinforcement of the road slab, anchoring the road slab to the bedrock subgrade.

[0025] The road slab is a cantilever structure, typically a half-width cantilever structure, meaning the width of the backfill subgrade is equal to the width of the bedrock subgrade. In this case, the boundary line between the backfill subgrade and the bedrock subgrade corresponds to the road centerline. The road slab is constructed directly on top of the backfill subgrade and the bedrock subgrade, without constructing the graded crushed stone subbase or cement-stabilized crushed stone base course.

[0026] Road slabs are spliced ​​along the road direction to form the pavement. The joints are transverse joints, which also serve as settlement joints. To accommodate uneven settlement of the retaining wall foundation, the settlement joints between adjacent road slabs correspond to the settlement joints of the retaining wall. No longitudinal joints are provided along the road direction for the road slabs. When a single road slab is long, at least one transverse joint is provided on the portion of the road slab located in the backfilled subgrade; no transverse joints are provided on the portion of the road slab located in the bedrock subgrade. The length direction of this portion is consistent with the longitudinal direction of the road, and the width direction is consistent with the transverse direction of the road. The transverse joints between the transverse joints and the road slabs are dummy joints without dowel bars. The longitudinal reinforcement of the road slabs is cut off at the locations of the transverse joints and transverse reinforcement bars.

[0027] The construction method of the cantilevered road structure on a rock slope of the present invention has the same beneficial effects as the aforementioned cantilevered road structure on a rock slope. The construction method of the cantilevered road structure on a rock slope does not require the construction of high retaining walls or pile foundations. A relatively low outer retaining wall is constructed on the upper part of the stockpile. Construction is uninterrupted, ensuring half-width traffic flow. The construction is simple and convenient, with low safety risks, short construction period, and cost savings.

[0028] The present invention also provides a method for treating settlement of a rock slope cantilever road structure. The method treats the settlement of a rock slope cantilever road structure constructed according to the above-mentioned construction method. Grouting holes are reserved or opened in the part of the road panel corresponding to the backfill subgrade. When the backfill subgrade settles, grouting is performed through the grouting holes.

[0029] Furthermore, the grouting holes in the road slab are sealed with temporary plugs. The grouting holes are opened before grouting and sealed after grouting. For example, the temporary plugs are made of clay.

[0030] The beneficial effects of the settlement treatment method for cantilevered road structures on rock slopes of the present invention are: the road panel is anchored by the bedrock subgrade, and the road panel adopts a cantilever structure. Even if settlement occurs on the side near the ditch or river, that is, the side corresponding to the backfill subgrade of the road, the backfill subgrade can be reinforced by grouting in time, without interrupting the road, ensuring safety, and the construction is simple, efficient and highly operable. Attached Figure Description

[0031] Figure 1 This is a schematic cross-sectional view of the rock slope cantilever road structure of the present invention.

[0032] Figure 2 yes Figure 1 A magnified view of a portion of the image.

[0033] Figure 3 This is a schematic diagram of the surface of two road panels spliced ​​together in the rock slope cantilever road structure of the present invention.

[0034] Figure 4 yes Figure 3 Cross-sectional view along the AA direction.

[0035] Attached reference numerals: 1. Outer retaining wall; 2. Road panel; 3. Backfill roadbed; 4. Anchor; 5. Grouting hole; 6. Grouting anchor; 7. Subbase; 8. Enlarged foundation; 9. Transverse joint; 10. Side ditch; 11. Roadbed slope; 12. Road centerline; 13. Natural slope or bedrock surface; 14. External boundary of the accumulation body; 15. Temporary support surface; 16. Guardrail; 17. Detailed Implementation

[0036] The invention will now be further described with reference to the accompanying drawings.

[0037] The first subject of this invention is a cantilevered road structure for rock slopes. For example... Figure 1 and Figure 2 As shown, the cantilevered road structure on a rock slope includes an outer retaining wall 1 and a road panel 2. The bottom of the outer retaining wall 1 is the outer retaining wall foundation, the inner side of the outer retaining wall 1 is the backfill roadbed 3, the side of the backfill roadbed 3 facing away from the outer retaining wall 1 is the bedrock roadbed, and the upper part of the backfill roadbed 3 and the bedrock roadbed is the road panel 2.

[0038] The foundation of the outer retaining wall is used to support the outer retaining wall 1. The outer retaining wall foundation does not require a pile foundation with complex construction techniques. See, for example... Figure 1 and Figure 2 The outer retaining wall foundation includes a solidified body obtained by grouting anchors 6 into the slab, a cushion layer 7 laid on top of the solidified body, and an enlarged foundation 8 laid on top of the cushion layer 7. Multiple rows of grouting anchors 6 are arranged longitudinally along the road, for example, 2-3 rows. The length of the grouting anchors 6 is generally 3-4m, and the upper end of the grouting anchors 6 is located within the enlarged foundation 8. To facilitate grouting, self-drilling hollow grouting anchors are selected for the grouting anchors 6, such as models A25 or A32. The cushion layer 7 serves for leveling and joint grouting. The outer retaining wall 1 is located on top of the enlarged foundation 8. The planar dimensions of the enlarged foundation 8 are larger than the bottom dimensions of the outer retaining wall 1, serving to distribute stress.

[0039] The outer retaining wall 1 forms a road shoulder. To improve the self-stability of the outer retaining wall 1, it is a counterweight retaining wall. To drain water from the backfill subgrade 3 inside the outer retaining wall 1, drainage holes are provided in the outer retaining wall 1, which can be formed by pre-embedding PVC pipes inside the outer retaining wall 1. A filter layer is provided on the inner side of the backfill subgrade 3 inside the outer retaining wall 1, which is used to cooperate with the drainage holes. To accommodate uneven settlement of the outer retaining wall foundation, settlement joints are also provided at intervals in the outer retaining wall 1, and settlement joints are also provided in the enlarged foundation 8 at positions corresponding to the settlement joints of the outer retaining wall 1.

[0040] Anchors 4 are installed within the bedrock subgrade, with their upper ends connected to the road panel 2. The road panel 2 is anchored to the bedrock subgrade, and when settlement occurs in the backfill subgrade 3, the road panel 2 becomes cantilevered. To facilitate the treatment of settlement between the outer retaining wall 1 and the backfill subgrade 3, grouting holes 5 are provided at the corresponding portions of the road panel 2 and the backfill subgrade 3. (See [reference]). Figure 3 There are multiple grouting holes 5, and they are preferably evenly arranged in rows and columns. To prevent rainwater from flowing into the backfill subgrade 3 through the grouting holes 5, temporary sealing bodies, such as clay, are installed inside the grouting holes 5. Normally, the grouting holes 5 are sealed. When grouting is needed, the temporary sealing bodies inside the grouting holes 5 are removed for grouting. After grouting, the grouting holes 5 are sealed again with temporary sealing bodies, which can achieve multiple backfilling and grouting.

[0041] The road panel 2 is a rigid structure, generally made of reinforced concrete. The inner side of the road panel 2 is a side ditch 11, one side of which is the excavated roadbed slope 12. The outer side of the road panel 2 is a guardrail 17, which is installed on top of the outer retaining wall 1. Based on the stress distribution of the road panel 2, the reinforcement of the road panel 2 includes transverse reinforcement, longitudinal reinforcement, and stirrups. Both the transverse and longitudinal reinforcement are arranged in double layers. See [reference needed]. Figure 4 The upper end of anchor 4 is connected to the reinforcement of road panel 2, thereby firmly anchoring road panel 2 to the bedrock subgrade. Anchor 4 is an anchor rod or anchor cable, for example, anchor 4 is a cement mortar anchor rod of type C22 or C25, and the length of the anchor rod is 3-4m. Anchor 4 is arranged in multiple parallel rows evenly, for example, at least two rows of anchor 4 are set along the longitudinal direction of the road. According to the stress of anchor 4 and for ease of construction, anchor 4 is preferably arranged vertically.

[0042] Based on the structural requirements and allowable deformation of the road panel 2, no longitudinal joints are provided along the road direction for the road panel 2. When the length of a single road panel 2 is small, the road panel 2 can be a single, jointless unit; when the length of a single road panel 2 is large, the portion of the road panel 2 located in the backfilled subgrade 3 has at least one transverse joint 9, while the portion of the road panel 2 located in the bedrock subgrade does not have a transverse joint 9. The length direction of the road panel 2 is consistent with the longitudinal direction of the road, and the width direction of the road panel 2 is consistent with the transverse direction of the road. The road panels 2 are spliced ​​end-to-end along the longitudinal direction of the road to form the road. The splicing joint between two adjacent road panels 2 is a transverse joint 10, which is a settlement joint and corresponds to the settlement joint of the outer retaining wall 1. For example, if the outer retaining wall 1 has settlement joints at intervals of 6-8m, and the length of a single road panel 2 is also 6-8m, and each road panel 2 has one transverse joint 9, such as... Figure 3 As shown. The transverse joint 10 between transverse joint 9 and road slab 2 is a dummy joint without dowel bars. The portion of the dummy joint closest to the road surface is filled with joint filler, such as... Figure 4 As shown, the longitudinal steel bars of the road panel 2 are cut off at the transverse joint 9.

[0043] The second subject of this invention is a method for constructing a cantilevered road structure on a rock slope, which is the construction method of the first subject mentioned above. The method for constructing a cantilevered road structure on a rock slope includes the following steps:

[0044] S1. Excavate the sludge to form the base of the external retaining wall foundation.

[0045] The accumulation is colluvial material or backfilled gravel and soil. At the location of the outer retaining wall 1 on the outer side of the road, excavation is carried out to a depth of 2m to 5m from the top elevation of the road surface, depending on the actual site conditions. The slope ratio of the temporary excavation on the inner side is not steeper than 1:1. The outer side can be excavated with a slope or by sweeping. The excavation method is determined based on the outer width and safety and economic needs. The base width is 2m to 3m. To ensure safety, shotcrete support can be applied to the temporary excavation surface on the inner side to form a temporary support surface 16.

[0046] S2. Construct the outer retaining wall foundation on the excavated and formed base. The outer retaining wall foundation is used to support the outer retaining wall 1. The following is a scheme for obtaining the outer retaining wall foundation by grouting, including S2.1 to S2.3.

[0047] S2.1 Grouting anchors 6 are installed and grouting is performed on the base, with an exposed section reserved for the grouting anchors 6. For example, 2-3 rows of self-propelled hollow grouting anchors are vertically installed on the base in a staggered pattern at 100cm intervals. The grouting anchors 6 are of model A25 or A32, each with a length L=3-4m. Grout is prepared according to a water:cement ratio of 1:1 and then injected. Grouting is performed according to the actual needs, with an average grouting volume of 400kg-600kg of cement injected into each grouting anchor 6. The upper end of the grouting anchor 6 is exposed for 30cm as a connecting component.

[0048] S2.2 Construct and level the foundation layer 7. The thickness of the foundation layer 7 is generally 10-20cm. Fine aggregate concrete with high slump and good workability, such as C20 fine aggregate concrete, can be used. The foundation layer 7 also serves to further fill and grout the joints.

[0049] S2.3 Construct the enlarged foundation 8 on top of the subbase 7.

[0050] The width of the enlarged foundation 8 is determined based on the bottom width of the outer retaining wall 1, generally by 50cm to 100cm on both the inner and outer sides of the outer retaining wall 1. The width of the enlarged foundation 8 is generally 2 to 4m, and its thickness is approximately 50cm. To accommodate uneven settlement, the enlarged foundation 8 is designed with joints at the settlement joint locations of the outer retaining wall 1. The exposed section of the grouting anchor 6 is located inside the enlarged foundation 8, ensuring an effective connection between the grouting anchor 6 and the enlarged foundation 8.

[0051] S3. Construct outer retaining wall 1 on top of the outer retaining wall foundation. Outer retaining wall 1 is preferably a counterweight retaining wall to improve its self-stability. Settlement joints are provided at intervals on outer retaining wall 1, for example, settlement joints are provided in sections of 6-8m. The counterweight retaining wall is cast in place, for example, using C20 concrete, with a wall height of 2-5m. To facilitate drainage of the backfilled roadbed 3 inside outer retaining wall 1, drainage holes are also provided on outer retaining wall 1. For ease of construction, drainage holes are obtained by pre-embedding pipes before casting outer retaining wall 1.

[0052] S4. Backfilling is carried out on the inner side of the outer retaining wall 1 to form the backfill roadbed 3. The backfill roadbed 3 should be backfilled in layers and compacted to reduce settlement. A filter layer is provided on the inner side of the outer retaining wall 1 in the backfill roadbed 3. The filter layer corresponds to the drainage holes of the outer retaining wall 1 to effectively drain accumulated water.

[0053] The above S1 to S4 refer to the construction of the outer retaining wall 1, and the following S5 to S6 refer to the construction of the road panel 2.

[0054] S5. Construct anchors 4 within the bedrock subgrade inside the backfilled subgrade 3.

[0055] Anchors 4 are mainly used to anchor the road panel 2, and can be anchor rods or anchor cables. There are multiple anchors 4, preferably arranged in rows and columns. Based on the stress on the anchors 4, they are preferably arranged vertically, with exposed sections to facilitate effective connection between the anchors 4 and the road panel 2. For example, on the bedrock subgrade on the mountainside of the road, at least two rows of anchor rods are arranged vertically downwards at 100cm intervals in both the longitudinal and transverse directions, with 30cm of the anchor rods exposed to form an effective connection with the road panel 2. The anchor rods are C22 or C25 cement mortar anchor rods, with a length of 3-4m.

[0056] S6. Construct road panel 2 on the upper part of backfilled roadbed 3 and bedrock roadbed, and connect the upper end of anchor 4 to road panel 2.

[0057] Road panel 2 is a reinforced concrete structure. The thickness, concrete strength, and reinforcement of road panel 2 are determined based on a comprehensive calculation of the highway grade, pavement width, and vehicle load. Road panel 2 is preferably designed as a half-width cantilever, meaning the boundary line between the backfill subgrade 3 and the bedrock subgrade at road panel 2 roughly corresponds to the road centerline 13. Based on the stress distribution of road panel 2, the reinforcement includes transverse and longitudinal reinforcement, both arranged in double layers. The upper end of the anchor 4 is connected to the reinforcement of road panel 2, anchoring road panel 2 to the bedrock subgrade. For example, the strength of road panel 2 is not less than C35, the thickness is 30-75cm, the transverse steel bars C25@200 (250) mm are arranged in two layers along the longitudinal direction of the road, the longitudinal steel bars C16@200 (250) mm are arranged in two layers along the longitudinal direction of the road, and A8 stirrups are set with a transverse spacing of 400 (500) mm and a longitudinal spacing of 200 (250) mm; the longitudinal steel bars are cut off at the joints, and the net protective layer thickness of the transverse and longitudinal steel bars is 50mm.

[0058] Road panel 2 is constructed directly on top of the backfilled subgrade 3 and bedrock subgrade, without the construction of graded crushed stone subbase and cement-stabilized crushed stone base course. Road panels 2 are spliced ​​along the road direction to form the pavement, with the splicing joints being transverse joints 10, which also serve as settlement joints. To accommodate uneven settlement of the retaining wall foundation, the settlement joints between adjacent road panels 2 correspond to the settlement joints of the retaining wall 1. For example, if a road panel 2 is installed every 6–8 m along the route, a corresponding settlement joint is also installed every 6–8 m in the outer retaining wall 1. See [link to relevant documentation] Figure 3 Road panel 2 does not have longitudinal joints arranged along the longitudinal direction of the road. When a single road panel 2 is long, the portion of road panel 2 located in the backfilled subgrade 3 has at least one transverse joint 9, while the portion of road panel 2 located in the bedrock subgrade does not have transverse joints 9. That is, transverse joints 9 are provided on the side of road panel 2 closest to the ditch, and no joints are provided on the side closest to the mountain. See, for example. Figure 3 Each road panel 2 is 6-8m long (along the road longitudinal direction), and each road panel 2 has a transverse joint 9. The transverse joint 10 between the transverse joint 9 and the road panel 2 is a dummy joint without dowel bars, such as... Figure 4 As shown, the upper part of the dummy joint is filled with joint filler, such as asphalt mastic, and the lower part of the dummy joint is directly spliced. The longitudinal steel bars of the road panel 2 are cut off at the position of the transverse joint 9.

[0059] The third aspect of this invention is a method for treating settlement in cantilevered road structures on rock slopes. This method addresses settlement issues in cantilevered road structures constructed according to the second aspect mentioned above. Grouting holes 5 are pre-installed or opened at the corresponding locations of the road panel 2 and the backfill subgrade 3. When settlement occurs in the backfill subgrade 3, grouting is performed through these grouting holes 5. The grouting holes 5 are normally sealed with temporary plugs. They are opened before grouting and closed after grouting. The number of rows and columns of grouting holes 5 can be adjusted according to the actual width of the subgrade. For example, four rows of 100mm diameter grouting holes 5 are pre-installed along the longitudinal direction of the road panel 2, with a rectangular arrangement of 100cm horizontally and 200cm vertically. The distance from the grouting hole 5 to the outer edge of the road panel should be ≥50cm, and the distance from the grouting hole 5 to the adjacent transverse joint 9 or transverse seam 10 should be 50-100cm. It is best to pre-embed PVC pipes for the grouting holes 5 during the pouring of the road panel 2, taking care to avoid the reinforcement of the road panel 2. Normally, grouting hole 5 is backfilled with clay and compacted. When grouting is needed, the clay is removed and grouting can be performed. After grouting, the hole is sealed with clay again, which can achieve the purpose of multiple backfilling and grouting.

[0060] This invention follows the principle of economic rationality, and does not construct an outer counterweight retaining wall according to existing technology, nor does it adopt external retaining forms such as pile foundation beam retaining wall or pile slab wall. Instead, it proposes a solution that fully understands and makes full use of the properties of the accumulated mass and bedrock, can adapt to backfill deformation, can maintain traffic even if deformation occurs, can reinforce the road, and prevent safety accidents.

Claims

1. A method of constructing a cantilevered road structure on a rock slope, characterized by: It comprises the following steps: S1, excavating the accumulation body to form the base of the construction outer retaining wall foundation; S2, constructing the outer retaining wall foundation on the base, comprising S2.1-S2.3: S2.1, laying the grouting anchor rod (6) on the base and grouting, the grouting anchor rod (6) is reserved with an exposed section; S2.2, constructing the cushion (7) on the base and leveling; S2.3, constructing the enlarged foundation (8) on the upper part of the cushion (7), the planar size of the enlarged foundation (8) is larger than the bottom size of the outer retaining wall (1); S3, constructing the outer retaining wall (1) on the upper part of the outer retaining wall foundation, the outer retaining wall (1) is provided with a settlement joint; S4, backfilling inside the outer retaining wall (1) to form the backfilled subgrade (3); S5, constructing the anchoring member (4) in the bedrock subgrade inside the backfilled subgrade (3), the anchoring member (4) is a vertically arranged anchor rod or anchor cable; S6, constructing the road panel (2) on the upper part of the backfilled subgrade (3) and the bedrock subgrade, the road panel (2) is a reinforced concrete structure, the reinforcement of the road panel (2) comprises transverse reinforcement, longitudinal reinforcement and stirrup, the transverse reinforcement and the longitudinal reinforcement are both arranged in double layers, the upper end of the anchoring member (4) is connected with the reinforcement of the road panel (2); the road panel (2) is spliced along the road direction to form a road surface, the spliced gap is a transverse joint (10), the transverse joint (10) between the adjacent two road panels (2) is a settlement joint and corresponds to the settlement joint of the outer retaining wall (1), the road panel (2) is not provided with a longitudinal joint arranged along the road direction, at least one transverse joint (9) is arranged in the part of the road panel (2) located in the backfilled subgrade (3), and the part of the road panel (2) located in the bedrock subgrade is not provided with a transverse joint (9).

2. The method of constructing a rock slope overhanging road structure according to claim 1, wherein: The outer retaining wall (1) in S3 is a counterweight retaining wall.

3. The method of constructing a rock slope overhanging road structure according to claim 1, wherein: The outer retaining wall (1) in S3 is provided with at least one water discharge hole, and the backfilled subgrade (3) in S4 is provided with a filter layer at the position inside the outer retaining wall (1).

4. A method of constructing a rock slope overhanging road structure as claimed in claim 1, 2 or 3 wherein: The transverse joint between the transverse joint (9) and the road panel (2) is a false joint without a force transmission rod.

5. The method for settlement treatment of rock slope overhanging road structure, characterized in that: The settlement of the rock slope overhanging type road structure constructed according to the construction method of the rock slope overhanging type road structure according to any one of claims 1-4 is treated, a grouting hole (5) is arranged in the part of the road panel (2) corresponding to the backfilled subgrade (3), and when the backfilled subgrade (3) settles, grouting is performed through the grouting hole (5).

6. The method of settlement treatment of rock slope overhanging road structure as claimed in claim 5 wherein: The grouting hole (5) of the road panel (2) is sealed by a temporary sealing body, the grouting hole (5) is opened before grouting and is closed after grouting.

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