Foundation reinforcing structure for solving bumping problem at bridgehead and construction method

Abstract

The invention relates to the technical field of foundation repair, in particular to a foundation reinforcing structure for solving the problem of bumping at a bridgehead and a construction method.The foundation reinforcing structure is arranged at an embankment and comprises a first row of jet grouting consolidating bodies and a second row of jet grouting consolidating bodies located in a foundation bed reinforcing area, and the first row of jet grouting consolidating bodies and the second row of jet grouting consolidating bodies are arranged in a staggered mode; the first row of jet grouting consolidation bodies and the second row of jet grouting consolidation bodies intersect on the central axis of the embankment to form a continuous latticed cemented soil framework, the horizontal distance between the jet grouting consolidation bodies in the same row is 3.0 m, and the two rows of jet grouting consolidation bodies are distributed in a crossed node mode in the vertical direction. The drilling direction of the first row of rotary jet grouting consolidation bodies is downward by forming a 15-degree inclination angle with the vertical plane, the drilling direction of the second row of rotary jet grouting consolidation bodies is downward by increasing the inclination angle formed by the drilling direction of the first row of rotary jet grouting consolidation bodies with the vertical plane by 5 degrees, and the projections of the two rows of rotary jet grouting consolidation bodies on the cross section of the existing roadbed slope are crossed in an X shape; a rigidity gradient layer from the bridge abutment to the roadbed is formed, rigidity abrupt change is eliminated, and traffic loads are decomposed into axial pressure and shear force through the cross nodes and evenly transmitted to the deep bearing layer through the grid framework.

Description

Technical Field

[0001] The present invention relates to the technical field of foundation repair, and in particular to a foundation reinforcement structure and a construction method for solving the problem of vehicle jumping at a bridge head. Background Art

[0002] Traditional overlay and leveling methods not only disrupt traffic and impact the environment, but also increase additional stress, triggering further subsidence. From a long-term and effective perspective, overlay and leveling methods cannot completely resolve the problem of vehicle derailment at existing highway bridges. Existing bridge derailment has long been a common problem in bridge construction, and traditional solutions often involve excavation and reconstruction, which is not only time-consuming and costly, but also significantly impacts traffic. Summary of the Invention

[0003] In order to solve the above problems, the present invention proposes a foundation reinforcement structure and a construction method for dealing with the bridge head vehicle jumping problem, so as to solve the above problems.

[0004] A foundation reinforcement structure is arranged at an embankment, comprising a first row of staggered jet-jet consolidation bodies and a second row of jet-jet consolidation bodies located in a base bed reinforcement area. The first row of jet-jet consolidation bodies and the second row of jet-jet consolidation bodies intersect in the central area of ​​the cross section of the embankment to form a continuous grid-like cement-soil skeleton.

[0005] The horizontal spacing between the same row of jet grouting consolidation bodies is 3.0m. The two rows of jet grouting consolidation bodies are distributed in a cross-node pattern in the vertical direction. The grid gaps form a natural drainage channel to prevent rainwater infiltration from causing frost heave and thaw settlement of the roadbed, thereby improving long-term stability.

[0006] The drilling direction of the first row of jet-jet consolidation bodies is downward at an angle of 10° to 20° with respect to the vertical plane.

[0007] The second row of jet-grouting consolidation is drilled in the same direction as the first row, with an angle of 5° downward. The projections of the two rows of jet-grouting consolidation on the cross-section of the existing roadbed slope form an X-shaped intersection, forming a gradual stiffness gradient from the abutment to the roadbed, eliminating sudden stiffness changes. The intersection nodes decompose the vehicle load into axial pressure and shear force, which are evenly transmitted to the deep bearing layer through the grid framework.

[0008] A construction method for a foundation reinforcement structure comprises the following steps:

[0009] The first step is to measure and lay out, and make a working platform on both sides of the roadbed in the bridge head jump area, 1.0m below the shoulder, to reserve space for the pressure to be released during rotary grouting to prevent the occurrence of rail over-top phenomenon.

[0010] Lay out high-pressure grouting pumps, water tanks, slurry barrels, mud mixers, cement tanks, pipe support rods, grouting pipes, jet-jet drilling rigs, etc. in sequence;

[0011] The high-pressure grouting pump, water tank, slurry barrel, mud mixer, cement tank, high-pressure hose and rotary jet drilling rig are connected through high-pressure hoses.

[0012] The second step is to use a jet grouting drill to drill a high-pressure jet grouting consolidation body along the existing roadbed slope and line direction.

[0013] Note: It is necessary to test and determine the safe distance between the rotary jet consolidation body formed behind the abutment and culvert and the abutment and culvert body.

[0014] During construction, the construction is carried out from top to bottom, and the diameter of the rotary jet consolidation body is 0.5m through the grouting pipe. The cement consumption per linear meter is generally not less than 210Kg, and it forms a 15° downward angle with the vertical plane to form the first row of rotary jet consolidation bodies.

[0015] In order to strengthen the strength of the base bed, the inclination angle of the first row of jet grouting consolidation bodies is increased by 5°, and the second row of jet grouting consolidation bodies is formed by jet grouting. The first row of jet grouting consolidation bodies and the second row of jet grouting consolidation bodies are 3.0m apart and are arranged in an alternating manner.

[0016] In the third step, the upper and lower rows and the two sides of the roadbed must be staggered to form a grid-like cement soil body, so that the first row of rotary grouting consolidation body and the second row of rotary grouting consolidation body intersect at the center of the embankment.

[0017] The fourth step is that the construction of the rotary grouting consolidation body should be carried out from the abutment to the roadbed in an upward direction, and the rotary grouting consolidation bodies formed by the same row of rotary grouting should be constructed in turns.

[0018] The fifth step is to use a crane to lift high-pressure grouting pumps, water tanks, slurry barrels, mud mixers, cement tanks, high-pressure hoses, rotary jet drilling rigs and other equipment onto or down the platform. If the equipment is less than 2m away from the power supply line, you must cooperate with the power supply team in the construction.

[0019] The drilling rig is placed at the designed grouting position. The allowable deviation of the drill rod during construction shall not exceed 1.5 degrees (i.e. 26 / 1000). The deviation between the drilling position and the designed position shall not exceed 100mm.

[0020] When the drilling rig or rotary jet grouting machine is in place, the seat must be stable, the vertical shaft or turntable must be aligned with the hole position, and the inclination angle must not exceed 1% of the design error.

[0021] The sixth step is slope test spraying. First, conduct a 0.5Mp low-pressure water jet test. If the pipeline is found to be blocked, repair it immediately until the pipeline is unblocked before proceeding to the next process.

[0022] Step 7: Drill underwater to the designed depth, increasing the drilling pressure to 5 MPa. After the first drill rod penetrates, stop the water jet, extend the drill rod, and continue drilling, cyclically drilling to the designed depth. Pay attention to the cable position during drilling.

[0023] Step 8: Prepare the slurry, drill and spray, and observe the expansion. Prepare the slurry from the water tank, mud mixer, and cement tank according to the designed mix ratio. Use a slurry bucket and a high-pressure grouting pump for stirring for at least 5 minutes, and then filter it twice through a 0.8mm mesh. In the process of jet grouting to form a jet grouting consolidation body to reinforce the roadbed, in order to prevent the slurry from setting for too long, the water in the slurry will seep into the roadbed, causing the roadbed to soften and sink. Generally, a water-reducing agent and a setting accelerator are required during the slurry preparation process. The dosage of the setting accelerator and water-reducing agent must be determined through experiments, and the setting time of the slurry is generally controlled to be 20-30 minutes.

[0024] Step 9: During the jet grouting process, some slurry often emerges from the grouting pipe wall. Observe the slurry emergence to promptly understand the soil conditions. A slurry emergence of less than 20% of the injected volume is considered normal. If it exceeds 20% or is completely absent, identify the cause and take appropriate measures. If the absence of slurry is caused by large voids in the stratum, increase the grouting volume in the voided area. Once the void is filled, resume normal jet grouting.

[0025] Step 10: After the spraying construction is completed, the grouting pipes and other equipment should be flushed clean. No cement slurry should remain in the pipes or equipment. Replace the slurry with water in the water tank and spray it on the ground to completely remove the slurry from the high-pressure grouting pump, high-pressure hose, and jet drilling rig.

[0026] Step 11: Move the equipment. Move the jet grouting rig and other equipment to the new grouting location and repeat the above steps to continue construction.

[0027] Compared with the existing technology, the present invention has the following beneficial effects: an X-shaped grid-like cement-soil skeleton is formed in the central area of ​​the embankment cross section through the staggered double-row rotary jet consolidation bodies. The cross nodes decompose the traffic load into axial pressure and shear force, which are evenly distributed to the deep bearing layer to avoid stress concentration; the difference in inclination angle forms a gradual stiffness layer from the abutment to the roadbed, eliminating rigidity mutations and reducing the bridge head jumping phenomenon; the grid gaps serve as natural drainage channels, blocking frost heave and thaw settlement caused by rainwater infiltration, and ensuring the long-term stability of the roadbed.

[0028] The construction method is centered on trenchless technology, which significantly improves efficiency and reduces costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0030] Figure 1 This is a working diagram of high-pressure grouting equipment;

[0031] Figure 2 It is a schematic diagram of the intersection of two rows of jet spray consolidation bodies;

[0032] Figure 3 Schematic diagram of the arrangement of two rows of rotary jet consolidation bodies.

[0033] In the picture:

[0034] 1. High-pressure grouting pump;

[0035] 2. Water tank;

[0036] 3. Pulp barrel;

[0037] 4. Mud mixer;

[0038] 5. Cement tank;

[0039] 6. High-pressure hose;

[0040] 7. Pipe support rod;

[0041] 8. Grouting pipe;

[0042] 9. Existing roadbed slope;

[0043] 10. Jet-jet drilling rig;

[0044] 11. Spray-jet consolidation;

[0045] 12. Base;

[0046] 13. The first row of jet spray consolidation body;

[0047] 14. The second row of rotary spray consolidation body;

[0048] 15. Embankment. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0050] The application principle of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0051] Example 1

[0052] like Figure 2-3 As shown, a foundation reinforcement structure is arranged at the embankment, including a first row of staggered jet-jet consolidation bodies 13 and a second row of jet-jet consolidation bodies 14 located in the base bed reinforcement area. The first row of jet-jet consolidation bodies 13 and the second row of jet-jet consolidation bodies 14 intersect in the central area of ​​the cross section of the embankment 15 to form a continuous grid-like cement-soil skeleton.

[0053] The horizontal spacing between the jet-jet consolidation bodies in the same row is 3.0 m, and the two rows of jet-jet consolidation bodies are distributed as cross nodes in the vertical direction.

[0054] The drilling direction of the first row of jet-jet consolidation bodies 13 is downwardly inclined at an angle of 10° to 20° relative to the vertical plane.

[0055] The drilling direction of the second row of jet-jet consolidation bodies 14 is the drilling direction of the first row of jet-jet consolidation bodies 13, with an inclination angle of 5° downward increased from the vertical plane. The projections of the two rows of jet-jet consolidation bodies on the cross section of the existing roadbed slope 9 form an X-shaped intersection.

[0056] By staggering double rows of rotary jet consolidation bodies, an X-shaped grid-like cement-soil skeleton is formed in the central area of ​​the embankment cross section. The cross nodes decompose the traffic load into axial pressure and shear force, which are evenly distributed to the deep bearing layer to avoid stress concentration; the difference in inclination angle forms a gradual stiffness layer from the abutment to the roadbed, eliminating sudden changes in rigidity and reducing the phenomenon of vehicle jumping at the bridge head; the grid gaps serve as natural drainage channels, blocking frost heave and thaw settlement caused by rainwater infiltration, and ensuring the long-term stability of the roadbed.

[0057] Example 2

[0058] like Figure 1-3 As shown, a construction method comprises the following steps:

[0059] (1) Measure and stake out the roadbed on both sides of the bridge head jump area, level the site to make a working platform, and lay out high-pressure grouting equipment, the equipment including a high-pressure grouting pump (1), a water tank (2), a slurry barrel (3), a mud mixer (4), a cement tank (5), a high-pressure hose (6), a pipe support rod (7), a grouting pipe (8) and a jet grouting drill (10);

[0060] (2) Drill a hole along the existing roadbed slope to the designed depth using a jet-jet drill, and inject cement slurry downward at an inclined angle under high pressure to form a jet-jet consolidation body;

[0061] (3) The jet-jet consolidation bodies are arranged alternately in the upper and lower rows and on both sides of the roadbed, with the upper row being the first row of jet-jet consolidation bodies (13) and the lower row being the second row of jet-jet consolidation bodies (14), with a spacing of 3.0 m, to form a grid-like cement soil structure;

[0062] (4) Monitor the grouting volume during the grouting process. When the grouting volume exceeds 20% of the grouting volume or no grouting occurs, adjust the grouting parameters.

[0063] (5) After the construction is completed, flush the grouting pipes and related equipment with clean water.

[0064] Directly reinforce the existing roadbed through rotary jet grouting without excavation and reconstruction, avoiding traffic interruption and significantly shortening the construction period; the normal threshold is a grouting volume of less than 20% of the grouting volume. If the limit is exceeded, adjust the parameters or fill the gaps to avoid slurry waste or uneven reinforcement.

[0065] The cement slurry ratio is:

[0066] Water-cement ratio: 0.8:1~1:1;

[0067] Accelerator dosage: 2% to 4%;

[0068] Water reducing agent dosage: 0.5%~1.0%;

[0069] The slurry setting time is controlled at 20-30 minutes. The cement slurry ratio is optimized to prevent the slurry from penetrating and softening the roadbed.

[0070] The cement slurry is filtered twice through a 0.8 mm sieve and sprayed at a pressure of 20-40 MPa during the drilling process, with a drilling speed of 0.15-0.25 m / min.

[0071] The construction direction of the jet grouting consolidation body is from the abutment back to the roadbed, and the same row of jet grouting consolidation bodies are constructed at intervals; the abutment is advanced towards the roadbed, and the same row of jet grouting consolidation bodies are constructed at intervals to reduce interference between adjacent operations. The working platform is set 1.0m below the shoulder, and space is reserved for the pressure release of the top rail.

[0072] This also includes a slope test grouting, during which a 0.5 MPa low-pressure water jet test is used to verify pipeline unobstructedness. Grouting can only be carried out after confirmation of no blockage. Compared to traditional "excavation and reconstruction" solutions, this approach saves significant manpower, materials, and traffic diversion costs.

[0073] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

[0074] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A foundation reinforcement structure, arranged at an embankment (15), characterized in that: The invention comprises a first row of jet-jet consolidation bodies (13) arranged in a staggered manner and a second row of jet-jet consolidation bodies (14) located in a base bed reinforcement area, wherein the first row of jet-jet consolidation bodies (13) and the second row of jet-jet consolidation bodies (14) intersect in the central area of ​​the cross section of the embankment (15), and intersect in the central area of ​​the cross section of the embankment (15) to form a continuous grid-shaped cement-soil skeleton; the intersection nodes of the grid skeleton constitute a load transfer hub, and the gaps between the grid skeleton constitute a natural drainage channel.

2. A foundation reinforcement structure according to claim 1, characterized in that: The horizontal spacing between the jet-jet consolidation bodies in the same row is 3.0 m, and the two rows of jet-jet consolidation bodies are distributed as cross nodes in the vertical direction.

3. A foundation reinforcement structure according to claim 2, characterized in that: The drilling direction of the first row of rotary jet consolidation bodies (13) is downward at an angle of 10° to 20° with respect to the vertical plane.

4. The foundation reinforcement structure according to claim 2, characterized in that: The drilling direction of the second row of jet-jet consolidation bodies (14) is the same as the drilling direction of the first row of jet-jet consolidation bodies (13), with the inclination angle formed by the vertical plane increased by 5° downward, and the projections of the two rows of jet-jet consolidation bodies on the cross section of the existing roadbed slope (9) form an X-shaped intersection.

5. A construction method comprising the foundation reinforcement structure according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Measure and stake out the roadbed on both sides of the bridge head jump area, level the site to make a working platform, and lay out high-pressure grouting equipment, the equipment including a high-pressure grouting pump (1), a water tank (2), a slurry barrel (3), a mud mixer (4), a cement tank (5), a high-pressure hose (6), a pipe support rod (7), a grouting pipe (8) and a jet grouting drill (10); (2) Drill a hole along the existing roadbed slope to the designed depth using a jet-jet drill, and inject cement slurry downward at an inclined angle under high pressure to form a jet-jet consolidation body; (3) The jet-jet consolidation bodies are arranged alternately in the upper and lower rows and on both sides of the roadbed, with the upper row being the first row of jet-jet consolidation bodies (13) and the lower row being the second row of jet-jet consolidation bodies (14), with a spacing of 3.0 m, to form a grid-like cement soil structure; (4) Monitor the grouting volume during the grouting process. When the grouting volume exceeds 20% of the grouting volume or no grouting occurs, adjust the grouting parameters. (5) After the construction is completed, flush the grouting pipes and related equipment with clean water.

6. A construction method according to claim 5, characterized in that: The cement slurry ratio is: Water-cement ratio: 0.8:1~1:1; Accelerator dosage: 2% to 4%; Water reducing agent dosage: 0.5%~1.0%; The slurry coagulation time is controlled to be 20-30 minutes.

7. A construction method according to claim 5, characterized in that: The cement slurry is filtered twice through a 0.8 mm sieve and sprayed at a pressure of 20-40 MPa during the drilling process. The drilling speed is 0.15-0.25 m / min, and the diameter of the rotary jet consolidation body is 0.5 m.

8. A construction method according to claim 5, characterized in that: The construction direction of the rotary jet grouting consolidation body is from the back of the abutment to the roadbed, and the rotary jet grouting consolidation bodies in the same row are constructed at intervals.

9. A construction method according to claim 5, characterized in that: It also includes slope test spraying. During the slope test spraying, a 0.5Mp low-pressure water jet test is used to check the smoothness of the pipeline. Only after confirming that there is no blockage can formal grouting be carried out.

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