Pre-buried anchor-buttress combined retaining wall structure and construction method

Abstract

The structure and construction method of the pre-buried anchor-buttress combined retaining wall belong to the field of geotechnical engineering technology. The inner side of the buttress retaining wall has multiple parallel inclined buttresses. There are reserved anchor holes on the facade of the buttress retaining wall, and the inner side is a backfilled gravel soil layer. The backfilled gravel soil layer is provided with a trough body, which includes an anchor free trough, an anchor anchoring trough and an enlarged head trough. The inner end of the anchor cable is formed into an anchor cable anchoring section and an enlarged head by pouring cement mortar in the anchor cable anchoring trough and the enlarged head trough. The multiple bundles of steel strands at the outer end of the anchor cable pass through the anchor cable free trough and are fixed by the reserved anchor holes and anchor heads. The multiple bundles of steel strands in the anchor cable free section and the anchor cable anchoring section are supported in the trough body by multiple centering brackets. The invention also provides a construction method. The prestressed anchor pull technology works in conjunction with the traditional buttress retaining wall to solve the problems of poor stability, large size and high cost of high buttress retaining wall working alone. The construction takes a short time, has low engineering cost and good quality.

Description

Technical Field

[0001] The invention belongs to the backfill slope retaining wall construction technology in the field of geotechnical engineering technology, and particularly relates to a pre-buried anchor-buttress combined retaining wall structure and a construction method, and is particularly suitable for a crushed stone backfill slope retaining wall. Background Art

[0002] As my country's urbanization process deepens, the scope of cities is getting larger and larger, and it begins to show an overall outward expansion trend, making more and more projects located in hilly areas that were previously less developed. In hilly landforms, most new sites have problems of unevenness and large height differences. In order to make the site level within a certain range and the bearing capacity meet the needs of the project, most sites will carry out backfilling and leveling work. Considering economic factors and construction process difficulties, more and more projects choose gravel soil as backfill material nearby. The backfill slope formed by backfilling gravel soil is mostly supported by retaining walls. The applicable slope support height of retaining walls is limited. When the slope height exceeds a certain limit, the use of retaining walls to support the slope will result in the retaining wall size and reinforcement being too large, which is no longer economical and reasonable.

[0003] As a commonly used support method in geotechnical slope engineering, anchor cables can provide resistance for various support structures and are an excellent support method. Conventional anchor cable retaining walls are divided into plate-rib anchor retaining walls, lattice anchor retaining walls and pile anchor retaining walls. Buttress retaining walls combined with anchor cables for support are a new form of support that can be used to solve problems such as excessive size and reinforcement of retaining walls on high slopes (10-30m), but it is extremely difficult to construct anchor cables in backfill gravel soil.

[0004] During the construction of slope anchor cables in geotechnical engineering, the hole-forming construction process of the anchor cable is crucial and will directly affect the implementation, quality and progress of the process. In the gravel soil layer, the anchor cable holes are mostly formed by eccentric follow-up drilling, that is, during normal drilling, the vibration impact of the impactor drives the eccentric drill to drill holes. During drilling, due to the centrifugal force and friction, the eccentric wheel deviates outward to achieve the purpose of expanding the hole diameter, and then the impact of the stabilizer drives the casing to follow up, and the rock powder generated by the drilling is blown out of the hole through the keyway on the stabilizer. After the drilling is completed, the eccentric wheel is reversed to retract and lift the casing, and the casing remains in the hole to protect the wall and form a hole.

[0005] However, when constructing gravel soil slopes, due to the extremely poor cohesion and integrity of the gravel soil, the loose gravel around the borehole will form a clamping effect due to the vibration of the drill rod during drilling, affecting the smooth progress of the drilling construction. There are disadvantages such as high cost, long construction period, large restrictions on equipment selection, limited construction length of the pipe shed, and difficulty in correcting deviation after deviation. However, the above difficulties can be effectively solved by prefabricating a buttress retaining wall with anchor holes and then pre-burying anchor cables during the slope backfill process to realize the anchor-buttress retaining wall structure and realize the joint working mode of the two support methods.

[0006] In summary, the use of retaining walls combined with anchor cables for slope support is an effective method to solve the problem of high fill slope support. However, developing an anchor cable construction method with low cost, high efficiency and good anchoring effect is an urgent problem to be solved. Summary of the invention

[0007] One object of the present invention is to provide a pre-buried anchor-buttress combined retaining wall structure, and another object of the present invention is to provide a construction method thereof, which adopts a mode of combined operation of prestressed anchor technology and traditional buttress retaining wall, and solves the problems of poor stability, large size and high cost of high buttress retaining wall when working alone. The construction method solves the problem of poor applicability of the prior art in restricted working conditions.

[0008] The technical solution adopted is:

[0009] The embedded anchor-buttress combined retaining wall structure comprises a buttress retaining wall, a backfill gravel soil layer and multiple anchor cable layers.

[0010] The technical points are:

[0011] The inner side of the L-shaped buttress retaining wall is provided with a plurality of buttresses arranged in parallel and inclined outwards.

[0012] A plurality of reserved anchor cable holes are arranged on the facade of the buttress type retaining wall, and the reserved anchor cable holes are located between the buttresses.

[0013] Each anchor cable layer includes a plurality of anchor cables, and each bundle of anchor cables includes a plurality of bundles of steel strands.

[0014] The inner side of the buttress retaining wall is backfilled with gravel soil.

[0015] A transversely arranged trench body is opened in the backfill gravel soil layer, and the trench body comprises an anchor cable free trench, an anchor cable anchoring trench and an enlarged head trench.

[0016] The inner end of the anchor cable is arranged in the anchor cable anchoring groove and the enlarged head groove, and a cement mortar layer is poured in the anchor cable anchoring groove and the enlarged head groove to form an anchor cable anchoring section and an enlarged head of a one-step formed integral structure.

[0017] The multiple strands of steel wire at the outer end of the anchor cable pass through the anchor cable free groove and are fixed through the reserved anchor cable hole and the anchor head outside the vertical surface of the buttress retaining wall. The anchor cable free groove is backfilled with a crushed stone soil layer.

[0018] Multiple bundles of steel strands in the free section of the anchor cable and the anchoring section of the anchor cable are supported in the trough body by multiple centering brackets.

[0019] The cross-sections of the anchor cable free groove and the anchor cable anchoring groove can be inverted isosceles trapezoids.

[0020] The outside of the steel strands in the free section of the anchor cable are all provided with anti-corrosion structures.

[0021] The invention also provides a construction method of a pre-buried anchor-buttress type combined retaining wall structure.

[0022] Its advantages are:

[0023] The prestressed anchor technology and the traditional buttress retaining wall work in combination mode solve the problems of poor stability, large size and high cost of high buttress retaining wall working alone. The construction method solves the problem of poor applicability of existing technology in restricted working conditions.

[0024] This technical solution is easy to operate and has low construction technology requirements. Compared with the traditional hole-opening and pouring process, this construction process is greatly simplified in terms of process. Through the pre-buried construction process, this solution can avoid the potential engineering quality risks brought by complex working conditions to the greatest extent. The traditional process has high requirements for the quality of the hole, ensuring that the drill bit has contacted the gravel soil layer before it can be rotated, and during the construction process, it must be ensured that the hole is in a clean state. Each time 0.3 to 0.5 meters are drilled, the powder is discharged. The operation process is complicated and the quality is difficult to guarantee.

[0025] This technical solution takes a short time to construct and has low engineering costs. The traditional construction process is complicated and takes a long time to construct; the slotting and pouring time of the embedded anchor cable is greatly shortened compared with the traditional construction process. This solution greatly reduces costs by avoiding the process of drilling holes under complex conditions of gravel soil.

[0026] This technical solution has good construction quality, high anchoring strength and good effect. Internal in-situ experiments have proved that the anchoring strength of this construction solution meets the requirements of national standards, and because the construction solution is simple and more controllable, it can better avoid the problem of some anchor strength not meeting the requirements due to harsh working conditions compared to traditional construction solutions.

[0027] This technical solution combines the traditional buttress retaining wall with embedded anchor cables for support, making it stronger. It solves the problems of excessive size and reinforcement of the traditional buttress retaining wall in high fill slope support, and proposes a new idea for solving the problem of high fill slope support.

[0028] This technical solution implements pre-embedded construction of the anchor cable, casts it in the excavated trench to form an anchor body, and finally forms a trapezoidal cross-section and an enlarged head. The pull-out resistance of the anchor cable is controlled by controlling the cross-sectional area and the cross-sectional area of ​​the enlarged head. It has the characteristics of simple construction process and good controllability, avoids the problems of traditional anchor cables in gravel soil, such as difficulty in drilling holes, poor drilling quality, high cost and long construction period, and greatly optimizes the traditional anchor cable construction process.

[0029] The above implementation scheme achieves the purpose of constructing pre-buried anchor cables in gravel soil, and works together with buttress retaining walls to form a pre-buried anchor-pull buttress combined retaining wall structure. It solves the problem of difficulty in drilling holes in gravel soil in traditional anchor cable construction methods. It is easy to operate and reduces the difficulty of construction; the anchor cable construction quality is good and the anchor cable anchoring effect is excellent. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is the front view of the present invention.

[0031] Figure 2 It is a schematic diagram of constructing a layer of anchor cables according to the present invention.

[0032] Figure 3 The trenching diagram for the construction of anchor cable anchor groove and anchor cable free groove.

[0033] Figure 4 It is a top view of the present invention.

[0034] Figure 5 Side view of a buttress retaining wall.

[0035] Figure 6 Schematic diagram of the anchor cable centering bracket structure.

[0036] Figure 7 Schematic diagram of the anti-corrosion structure of the free section of the anchor cable.

[0037] Figure 8 It is a schematic diagram of the structure of the anchor cable and the centering bracket.

[0038] Anchor head 1, steel strand 2, anchor cable free section 3, anchor cable anchoring section 4, enlarged head 5, buttress retaining wall 6, backfill gravel soil layer 7, trough body 8, centering bracket 9, cement mortar layer 10, fixed pipe 11, support leg 12, anti-corrosion paint layer 13, anti-corrosion casing 14, anti-corrosion grease layer 15, reserved anchor cable hole 16, buttress 17, anchor cable 18, drainage hole 19, anchor cable anchoring groove 20, enlarged head groove 21, anchor cable free groove 22. DETAILED DESCRIPTION

[0039] Example 1

[0040] The pre-buried anchor-buttress combined retaining wall structure comprises a buttress retaining wall 6, a backfill gravel soil layer 7 and multiple anchor cable layers.

[0041] The inner side of the L-shaped buttress retaining wall 6 is provided with a plurality of buttresses 17 arranged in parallel and tilted, and the two ends of the buttress 17 are located at the vertical wall top and the horizontal bottom plate end of the buttress retaining wall 6 respectively.

[0042] A plurality of reserved anchor holes 16 are provided on the facade of the buttress retaining wall 6, and the reserved anchor holes 16 are located between the buttresses 17 and staggered in upper and lower positions. For example, one part is provided with holes at three corners of a regular triangle, and the adjacent part is provided with holes at three corners of an inverted triangle, which is arranged in a plum blossom shape.

[0043] The height of the reserved anchor cable hole 16 corresponds to the position of the anchor cable 18 .

[0044] Each anchor cable layer includes a plurality of anchor cables 18, and each bundle of anchor cables 18 includes a plurality of bundles of steel strands 2. In this embodiment, there are three bundles of steel strands 2.

[0045] The inner side of the buttress retaining wall 6 is a backfill gravel soil layer 7.

[0046] A transversely arranged slot body 8 is provided in the backfill gravel soil layer 7 , and the slot body 8 comprises an anchor cable free slot 22 , an anchor cable anchoring slot 20 and an enlarged head slot 21 .

[0047] The inner end of the anchor cable 18 is arranged in the anchor cable anchoring groove 20 and the enlarged head groove 21, and the anchor cable anchoring section 4 and the cement mortar enlarged head 5 of the one-time integral structure are formed by pouring a cement mortar layer 10 in the anchor cable anchoring groove 20 and the enlarged head groove 21.

[0048] The multiple strands 2 at the outer ends of the anchor cables 18 pass through the anchor cable free groove 22 and are fixed by the reserved anchor cable holes 16 and the anchor heads 1 outside the vertical surface of the buttress retaining wall 6. The anchor cable free groove 22 is backfilled with a crushed stone soil layer 7.

[0049] Furthermore, the multiple strands of steel strands 2 in the free section 3 of the anchor cable are supported in the free groove 22 of the anchor cable by multiple centering brackets 9 .

[0050] Furthermore, the multiple strands of steel strands 2 in the anchor cable anchoring section 4 are supported in the anchor cable anchoring groove 20 by multiple centering brackets 9 .

[0051] Furthermore, the cross-sections of the anchor cable free groove 22 and the anchor cable anchoring groove 20 may be inverted isosceles trapezoids.

[0052] The cross section of the enlarged head groove 21 can be circular, trapezoidal or rectangular.

[0053] The AA cross-sectional area of ​​the enlarged head 5 is larger than the trapezoidal cross-sectional area of ​​the groove body 8 .

[0054] The centering bracket 9 has two coaxially arranged fixed tubes 11 (steel tubes), and the two fixed tubes 11 are connected by a plurality of outwardly extending legs 12 (rebars). Two adjacent legs 12 form a pair, and a bundle of steel strands 2 of an anchor cable 18 is arranged in the middle. In this embodiment, the anchor cable 18 has three bundles of steel strands 2, and there are six legs 12, which clamp a bundle of steel strands 2 in pairs.

[0055] Each bundle of steel strands 2 is placed at the contact point between the supporting leg 12 and the fixing pipe 11 so that the steel strands 2 do not contact the edge of the tank body 8.

[0056] Furthermore, the outer sides of the three strands 2 of the anchor cable free section 3 are all provided with an anti-corrosion structure, which is a conventional technical means in the art. One method that can be used is:

[0057] The anti-corrosion structure includes an anti-corrosion paint layer 13 , an anti-corrosion casing 14 and an anti-corrosion grease layer 15 .

[0058] The steel strands 2 are provided with anti-corrosion sleeves 14. The anti-corrosion sleeves 14 can be high-density polyvinyl chloride anti-corrosion sleeves.

[0059] The steel strand 2 may also be coated with at least one layer of anti-corrosion paint 13, two layers in this embodiment.

[0060] An anti-corrosion grease layer 15 is sealed between the anti-corrosion paint layer 13 and the anti-corrosion casing 14 .

[0061] The anti-corrosion paint is a conventional anti-corrosion paint for steel strands in the art and is a known product available on the market. The anti-corrosion grease may be butter.

[0062] Furthermore, a plurality of drainage holes 19 are provided at the bottom of the facade of the buttress retaining wall 6 .

[0063] Furthermore, the length of the free section 3 of the anchor cable is shorter than the length of the bottom plate of the buttress retaining wall 6 .

[0064] Example 2

[0065] The embedded anchor-buttress combined retaining wall structure and construction method include the following steps:

[0066] 1. Construction of retaining wall: Construction of buttress retaining wall 6 (buttress 17 spacing is about 4m to 7m), and reserved anchor holes 16 on the vertical surface of the buttress retaining wall 6 between buttresses 17. The horizontal spacing of the reserved anchor holes 16 is 1m to 3.5m, the vertical spacing is 2m to 6m, and they are distributed in a plum blossom shape. The diameter of the reserved anchor holes 16 is 50mm to 150mm, and the horizontal angle is maintained. A plurality of drainage holes 19 are set at the bottom of the vertical surface of the buttress retaining wall 6.

[0067] 2. Backfill gravel soil: After the construction of the buttress retaining wall 6 is completed and meets the strength requirements, the gravel soil layer 7 is backfilled in layers and compacted. The compaction coefficient shall not be less than 0.97. Backfill to the position of the lowest reserved anchor hole 16 to prepare for the construction of multiple pre-buried anchor cables 18 in this layer.

[0068] 3. Anchor cable anchor body slotting: slotting is performed at the position of each anchor cable 18. The slot body 8 is divided into three parts, the anchor cable free slot 22, the anchor cable anchoring slot 20 and the enlarged head slot 21. The cross-sections of the anchor cable free slot 22 and the anchor cable anchoring slot 20 are inverted isosceles trapezoids, and the cross-section of the enlarged head slot 21 (AA) is an inverted isosceles trapezoid. The cross-sectional area of ​​the slot body 8 meets the design requirements.

[0069] For example, the trapezoidal area shall not be less than 0.1㎡, but not greater than the cross-sectional area of ​​the enlarged head 5. In this embodiment, the trapezoidal area is 0.2㎡, the length of the trough body 8 is 15m~30m, the cross-sectional area of ​​the enlarged head 5 is 0.5㎡~2㎡ (AA), the cross-sectional area of ​​the enlarged head 5 is selected to be 0.5㎡, the length of the enlarged head 5 is 2m~5m, the length of the anchor free section 3 is 5m~10m, and the length of the anchor anchoring section 4 is 10m~20m.

[0070] 4. Anchor cables 18 are arranged in the anchor cable anchoring groove 20 and the enlarged head groove 21, and multiple centering brackets 9 are arranged in the anchor cable anchoring groove 20 (the centering bracket spacing is 1.5m). The anchor cable anchoring groove 20 and the enlarged head groove 21 are poured with cement mortar with a strength not less than M30, a cement mortar layer 10 is formed in the anchor cable anchoring section 4, and an enlarged head 5 is formed at the end of the anchor cable anchoring section 4.

[0071] After the anchor strength of the anchor cable anchoring section 4 reaches the set requirement (24Mpa), a plurality of centering brackets 9 are arranged in the anchor cable free groove 22, the steel strand 2 at the anchor cable free section 3 is tensioned at the end of the vertical surface of the buttress retaining wall 6 and fixed with the outer locking anchor head 1, and the gravel soil layer 7 is backfilled in the anchor cable free groove 22.

[0072] The steel strand 2 at the free section 3 of the anchor cable has been pre-treated for corrosion, which is a routine operation.

[0073] 5. Anchor cable tensioning: After the solid strength of the multiple anchor cable anchoring sections 4 in each layer reaches the set requirement (24Mpa), continue to backfill the gravel soil layer 7 in layers and compact it, backfill upward to the elevation of the next anchor cable 18, tension the anchor cable 18 and lock it. The anchor cable 18 should be pre-tensioned to 20% of the design value of the axial bearing capacity, and then tensioned to the design value of the axial bearing capacity. The load holding time should be no less than 5 minutes, and then retreat to the prestressed locking value for locking.

[0074] 6. Repeat the above steps to complete each anchor cable layer, and backfill upward to the backfill gravel soil layer 7 to the top of the buttress retaining wall 6.

[0075] 7. Acceptance test should be carried out after construction is completed.

[0076] 8. After construction is completed, deformation and health monitoring should be carried out within a certain period to understand the deformation law of the slope and take safety measures when necessary to prevent engineering accidents.

Claims

1. A pre-buried anchor-buttress combined retaining wall structure, comprising a buttress retaining wall (6), a backfill gravel soil layer (7) and a multi-layer anchor cable layer; characterized in that: The inner side of the L-shaped buttress retaining wall (6) is provided with a plurality of buttresses (17) arranged in parallel and inclined outwards; A plurality of reserved anchor cable holes (16) are provided on the facade of the buttress-type retaining wall (6), and the reserved anchor cable holes (16) are located between the buttresses (17); Each anchor cable layer comprises a plurality of anchor cables (18), and each bundle of anchor cables (18) comprises a plurality of bundles of steel strands (2); The inner side of the buttress retaining wall (6) is backfilled with a gravel soil layer (7); A transversely arranged trough body (8) is provided in the backfill gravel soil layer (7), and the trough body (8) comprises an anchor cable free trough (22), an anchor cable anchoring trough (20) and an enlarged head trough (21); The inner end of the anchor cable (18) is arranged in the anchor cable anchoring groove (20) and the enlarged head groove (21), and a cement mortar layer (10) is poured in the anchor cable anchoring groove (20) and the enlarged head groove (21) to form an anchor cable anchoring section (4) and an enlarged head (5) of a one-step formed integral structure; The plurality of strands (2) at the outer end of the anchor cable (18) pass through the anchor cable free groove (22) and are fixed through the reserved anchor cable hole (16) and the anchor head (1) outside the vertical surface of the buttress retaining wall (6); the anchor cable free groove (22) is backfilled with a gravel soil layer (7).

2. The pre-buried anchor-buttress combined retaining wall structure according to claim 1 is characterized in that: The plurality of strands (2) in the anchor cable free section (3) and the anchor cable anchoring section (4) are supported in the groove body (8) by a plurality of centering brackets (9); the cross-sections of the anchor cable free groove (22) and the anchor cable anchoring groove (20) are inverted isosceles trapezoids.

3. The pre-buried anchor-buttress combined retaining wall structure according to claim 2 is characterized in that: The centering bracket (9) has two coaxially arranged fixed tubes (11), the two fixed tubes (11) are connected via a plurality of outwardly extending legs (12), two adjacent legs (12) form a pair, and a bundle of steel strands (2) of an anchor cable (18) is arranged in between.

4. The embedded anchor-buttress combined retaining wall structure according to claim 1 is characterized in that: The outer sides of the steel strands (2) of the free section (3) of the anchor cable are all provided with anti-corrosion structures.

5. The embedded anchor-buttress combined retaining wall structure according to claim 4 is characterized in that: The steel strand (2) is sheathed with an anti-corrosion casing (14).

6. The embedded anchor-buttress combined retaining wall structure according to claim 5 is characterized in that: The steel strand (2) is coated with at least one layer of anti-corrosion paint (13), and a sealing anti-corrosion grease layer (15) is provided between the anti-corrosion paint layer (13) and the anti-corrosion casing (14).

7. The method for constructing a pre-buried anchor-buttress combined retaining wall structure according to claim 1, characterized in that The following steps are involved: 1) Construction of retaining wall: Construction of buttress retaining wall (6), and reservation of anchor cable holes (16) on the vertical surface of the buttress retaining wall (6) between buttresses (17); 2) Backfilling gravel soil: After the buttress retaining wall (6) is constructed and meets the strength requirements, backfill the gravel soil layer (7) in layers and compact it, backfill to the position of the lowest reserved anchor cable hole (16), and prepare to construct multiple pre-buried anchor cables (18) in this layer; 3) Anchor cable anchor body slotting: slotting is performed at each anchor cable (18), the slot body (8) comprises three parts, the anchor cable free slot (22), the anchor cable anchoring slot (20) and the enlarged head slot (21), and the cross-sectional area of ​​the slot body (8) meets the design requirements; 4) A cement mortar layer is poured on the anchor cable anchoring slot (20) and the enlarged head slot (21) to form an anchor cable anchoring section (4), and an enlarged head (5) is formed at the end of the anchor cable anchoring section (4); After the anchor strength of the anchoring body of the anchor cable anchoring section (4) reaches the set requirements, the steel strand (2) at the free section (3) of the anchor cable is tensioned at the end of the vertical surface of the buttress retaining wall (6) and fixed using the outer locking anchor head (1), and the gravel soil layer (7) is backfilled in the free groove (22) of the anchor cable; 5) Anchor cable tensioning: After the solid strength of the multiple anchor cable anchoring sections (4) of each layer reaches the set requirements, the gravel soil layer (7) is backfilled in layers and compacted, and backfilled upward to the elevation of the next anchor cable (18), and the anchor cable (18) is tensioned to the design requirements and locked; 6) Repeat the above steps to complete each anchor cable layer, and then backfill the gravel soil layer (7) upwards to the top of the buttress retaining wall (6).

8. The method for constructing a pre-buried anchor-buttress combined retaining wall structure according to claim 7, characterized in that The following steps are involved: The anchor cable (18) is arranged in the trough body (8) via a plurality of centering brackets (9).

9. The method for constructing a pre-buried anchor-buttress combined retaining wall structure according to claim 7, characterized in that The following steps are involved: The cross sections of the anchor cable free groove (22) and the anchor cable anchoring groove (20) are inverted isosceles trapezoids.

10. The method for constructing a pre-buried anchor-buttress combined retaining wall structure according to claim 7, characterized in that The following steps are involved: The steel strand (2) at the free section (3) of the anchor cable is subjected to anti-corrosion treatment.

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