Double-liquid grouting construction method for reinforcing foundations around box culvert and pipeline

Abstract

The invention relates to the technical field of box culvert pipeline construction, in particular to a double-liquid grouting construction method for reinforcing foundations around a box culvert and a pipeline, which comprises the following steps: S1, determining a construction area; s3, preparing a grouting material; s4, sleeve valve pipe installation; s5, grouting construction is conducted; and S6, judging final irrigation. According to the method provided by the invention, aiming at the particularity of the foundation around the box culvert and the pipeline, the reinforcement area is accurately delimited, so that the foundation reinforcement covers the stress key area of the structure, and no redundant road space is occupied; the plum blossom type hole position arrangement is adopted, mutual interference of adjacent grouting holes is effectively reduced, and grout is evenly diffused in miscellaneous fill and a soft soil layer; core parameters of the double-liquid slurry are determined, the grouting amount of a unit reinforcement body is reduced, the consumption of cement and water glass is greatly reduced while the slurry solidification time is guaranteed, and the construction cost is low; a technical basis is provided for similar box culvert and pipeline surrounding foundation reinforcement engineering, and the application value is high.

Description

Technical Field

[0001] This invention relates to the field of box culvert and pipeline construction technology, specifically to a two-liquid grouting construction method for reinforcing the foundation around box culverts and pipelines. Background Technology

[0002] Municipal stormwater culverts and sewage pipes are core infrastructure of urban drainage systems, and their stable operation is directly related to the city's flood control and drainage capacity and water environment safety. Currently, the industry widely adopts general dual-liquid grouting technology for foundation reinforcement. However, this technology has significant drawbacks when applied to culverts and pipelines: First, the delineation of construction areas lacks specificity, failing to optimize the scope based on the burial depth, direction, and surrounding road layout of the culverts and pipelines, easily leading to incomplete reinforcement or resource waste. Second, the borehole layout often adopts a single-spacing pattern, failing to consider the stress distribution characteristics of the surrounding strata, which can easily cause compression and disturbance to the pipeline during grouting. Third, the grouting material mix ratio often relies on empirical values ​​without verifying its suitability through test sections. In some projects, unreasonable water-cement ratios result in excessive grouting volume per unit, increasing construction costs. Fourth, the design of the construction sequence and final grouting standards is often rudimentary, failing to adopt the skip-hole construction logic of starting with the outer perimeter and then moving to the inner perimeter. This leads to significant interference between adjacent boreholes, and the final grouting is judged solely by pressure or grout absorption, easily resulting in insufficient or excessive grouting. Fifth, there is a lack of specific measures for the protection of culverts / pipelines, leading to frequent grout leakage during the grouting process, which can easily damage surrounding pipeline facilities. Summary of the Invention

[0003] The purpose of this invention is to provide a dual-liquid grouting construction method that is suitable for special scenarios around box culverts and pipelines, has precise parameters, is controllable in construction, and can ensure reinforcement effect.

[0004] This invention is achieved through the following technical solution: a two-component grouting construction method for reinforcing the foundation around box culverts and pipelines, comprising the following steps: Step S1: Determine the construction area: For the foundation around the rainwater culvert and sewage pipe, delineate the reinforcement area, and the reinforcement depth is 1m below the pipe after the pipe repair is completed; Step S2: Arrange the grouting holes in a quincunx pattern, with a hole spacing of 1.5m × 1.5m, for a total of 4 rows of grouting holes, with a row spacing of 1.2m to 1.5m; Step S3: Use a two-component slurry, which is composed of ordinary silicate cement and water glass, with a cement to water glass weight ratio of 1:1 and a cement slurry water-cement ratio of 0.8:1. Step S4: Drill holes with a diameter of 70mm~110mm and a drilling depth of 3m~6m. After drilling, embed a sleeve valve pipe with an inner diameter of 50mm. The grouting section is a perforated pipe with plum blossom-shaped injection holes, and the non-grouting section is a solid pipe. Wrap the injection holes with 5cm~8cm rubber sleeve valves and pour casing material to fix the sleeve valve pipe. Grouting is carried out 24 hours after the sleeve valve pipe is fixed. Step S5: Use the sleeve valve pipe pure pressure grouting method, control the grouting pressure at 0.5MPa, and the grouting speed at 30L / min~35L / min; the construction sequence is to first construct the outer row 1 and 4 grouting holes, and then construct the inner row 2 and 3 grouting holes. Within the same row, construct the first sequence hole first and then the second sequence hole, using a skip-hole interval construction method. Step S6: Stop grouting when cracks, grout leakage, or ground heave occur on the ground, or when the grouting pressure reaches 0.5MPa and the injection volume is basically not absorbed.

[0005] To better implement the method of the present invention, in step S3, the water glass used has a modulus of 3.1 to 3.4, a Baumé degree of 40°Be, and a specific gravity of 1.38.

[0006] To better implement the method of the present invention, in step S4, the drilling depth is adjusted according to the results of the on-site pipeline network exploration, and the thickness of the overburden layer above the grouting point is not less than 1.0m.

[0007] To better implement the method of the present invention, in step S5, the specific method of skip-hole interval construction is as follows: after the construction of adjacent I sequence holes in the same row is completed, II sequence holes are constructed after a gap of at least 1 hole position.

[0008] To better implement the method of the present invention, in step S5, the grouting construction is carried out in 2 to 4 times, with an interval of 10 to 20 minutes after each grouting, until the final grouting standard is met.

[0009] To better implement the method of the present invention, the method further includes step S7: quality inspection is carried out within 7 to 28 days after grouting is completed. The inspection methods include light dynamic penetration test and shallow plate load test; wherein, the standard value of N10 hammer blows for light dynamic penetration test is not less than 30 blows, and the characteristic value of foundation bearing capacity measured by shallow plate load test is not less than 20 kPa.

[0010] To better implement the method of the present invention, further, after stopping grouting in step S6, a sealing step is also included, that is, cement mortar is injected into the grouting hole multiple times until the cement mortar no longer sinks.

[0011] To better implement the method of the present invention, in step S3, the water-cement ratio of the cement grout is determined by verification through a test section: when the test section uses a water-cement ratio of 1:1, if the unit grouting volume is too large, it is adjusted to 0.8:1 to reduce the grouting volume of the unit solidified material.

[0012] To better implement the method of the present invention, further, in step S5, if grout leakage occurs on the ground during the grouting construction process, grouting is immediately stopped, the leakage outlet is manually sealed, and after a period of time, grouting is resumed until the final grouting standard is met.

[0013] To better implement the method of the present invention, in step S3, the fineness requirement of ordinary Portland cement is: passing through an 80μm square hole sieve with a sieve residue of no more than 5%; when the opening of the box culvert joint is less than 0.5mm, the fineness of the cement is adjusted to pass through a 71μm square hole sieve with a sieve residue of no more than 2%.

[0014] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) This invention addresses the special characteristics of the foundation around the box culvert and pipeline by accurately delineating the reinforcement area and optimizing the construction layout by combining the burial depth and direction of the rainwater box culvert and sewage pipeline. This avoids problems caused by the reinforcement area being too large or too small, ensuring that the foundation reinforcement covers the key stress area of ​​the structure without occupying extra road space. During the construction process, it does not disturb the box culvert, pipeline and surrounding sewage wells and information wells, thus solving the defect of poor adaptability of general technology to specific scenarios. (2) The present invention adopts a 4-row plum blossom-shaped hole arrangement and follows the method of first constructing the outer 1st and 4th rows, then constructing the inner 2nd and 3rd rows, and skipping the holes in the same row first sequence I holes then sequence II holes, which effectively reduces the mutual interference between adjacent grouting holes and makes the grout spread evenly in the miscellaneous fill soil and soft soil layer. (3) The present invention verifies and determines the core parameters of the dual-liquid grout through test sections, which greatly reduces the amount of grout injected per unit of solidified material. While ensuring the grout setting time, it also greatly reduces the consumption of cement and water glass. Furthermore, the fineness of the cement is adjusted according to the scenario to further ensure the grouting reinforcement effect. (4) This invention uses a drilling rig to drill holes and pre-embed sleeve valve pipes with rubber sleeve valves, and controls the grouting pressure and grouting speed. At the same time, it designs a process of immediately stopping grouting, manually sealing, and intermittent re-grouting to deal with grout leakage, which effectively avoids grout waste and ground heave. At the final grouting, a dual judgment standard of pressure compliance and ground phenomenon is adopted to prevent insufficient or excessive grouting. (5) This invention completely solves the problems of loose fill soil and insufficient bearing capacity of soft soil foundation by quality inspection after grouting, effectively prevents the settlement of box culverts and pipelines and ground collapse, and ensures the long-term stable operation of municipal roads and drainage systems. Compared with the existing technology, the reinforcement effect is more durable and reliable. (5) The present invention adds a cement mortar sealing step after final grouting to avoid the formation of voids in the grouting hole, which would lead to subsequent foundation settlement. It provides a replicable technical solution for similar box culvert and pipeline foundation reinforcement projects, and has high application value. Attached Figure Description

[0015] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a flowchart illustrating the construction process of the present invention. Detailed Implementation

[0016] To make the objectives, process conditions, and advantages of the present invention clearer, the present invention will be further described in detail with reference to the following embodiments. However, the embodiments of the present invention are not limited thereto. Various substitutions and modifications can be made based on common technical knowledge and conventional means in the art without departing from the above-described technical concept of the present invention, and all such substitutions and modifications should be included within the scope of the present invention. The specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0017] Example 1: This embodiment provides a two-component grouting construction method for reinforcing the foundation around box culverts and pipelines. The specific construction process is as follows: Figure 1 As shown, it includes the following steps: Step S1: For the foundation around the rainwater culvert and sewage pipe, delineate the reinforcement area, and the reinforcement depth is 1m below the pipe after the pipe repair is completed; Step S2: Arrange the grouting holes in a quincunx pattern, with a hole spacing of 1.5m × 1.5m, for a total of 4 rows of grouting holes, with a row spacing of 1.2m to 1.5m; Step S3: Use a two-component slurry, which is composed of ordinary silicate cement and water glass, with a cement to water glass weight ratio of 1:1 and a cement slurry water-cement ratio of 0.8:1. Step S4: Drill holes with a diameter of 70mm~110mm and a drilling depth of 3m~6m. After drilling, embed a sleeve valve pipe with an inner diameter of 50mm. The grouting section is a perforated pipe with plum blossom-shaped injection holes, and the non-grouting section is a solid pipe. Wrap the injection holes with 5cm~8cm rubber sleeve valves and pour casing material to fix the sleeve valve pipe. Grouting is carried out 24 hours after the sleeve valve pipe is fixed. Step S5: Use the sleeve valve pipe pure pressure grouting method, control the grouting pressure at 0.5MPa, and the grouting speed at 30L / min~35L / min; the construction sequence is to first construct the outer row 1 and 4 grouting holes, and then construct the inner row 2 and 3 grouting holes. Within the same row, construct the first sequence hole first and then the second sequence hole, using a skip-hole interval construction method. Step S6: Stop grouting when cracks, grout leakage, or ground heave occur on the ground, or when the grouting pressure reaches 0.5MPa and the injection volume is basically not absorbed.

[0018] Example 2: This embodiment, based on the above embodiment, further specifies that in step S3, the water glass used has a modulus of 3.1 to 3.4, a Baume degree of 40°Be, and a specific gravity of 1.38. The setting time of the slurry after mixing with cement must be controlled within the range of 35 to 50 seconds. Simultaneously, the water glass must be stored in a cool, ventilated place, and its Baume degree must be tested before use. If the Baume degree decreases due to prolonged storage, the mix ratio with cement must be readjusted to ensure stable slurry setting performance.

[0019] Example 3: This embodiment, based on the above embodiment, further specifies that in step S4, the drilling depth needs to be dynamically adjusted according to the results of on-site pipeline exploration. The actual location and depth of the underground pipeline network are determined through manual excavation or geophysical exploration. If the drilling path encounters a pipeline network, the drilling depth needs to be adjusted appropriately to avoid it. Simultaneously, considering the project's geological characteristics, the drilling depth must ensure that the grouting section covers key areas of soft soil strata. Furthermore, the thickness of the overburden layer above the grouting point is strictly controlled to be no less than 1.0m to avoid the grouting pressure directly acting on the ground and causing heave. The overburden material must be undisturbed soil or compacted subgrade soil. If the overburden layer is insufficient, it must be backfilled and compacted to meet the thickness requirements.

[0020] Example 4: This embodiment, based on the above embodiment, further specifies that in step S5, after the construction of adjacent I-sequence holes in the same row is completed, II-sequence holes are constructed only after a gap of at least one hole position. For example, if the hole positions in the row are numbered S1-1, S1-2, S1-3, S1-4, and S1-5, I-sequence holes S1-1, S1-3, and S1-5 are constructed first, and after their grouting is completed and the grout has initially set, II-sequence holes S1-2 and S1-4 are constructed. This method can achieve a sequential and denser reinforcement effect. According to the project test data, the cement unit injection volume of I-sequence holes in the test area is 1021.84 kg / m, and that of II-sequence holes is 590.92 kg / m, with the unit injection volume of II-sequence holes decreasing by 50.1% compared to I-sequence holes; the cement unit injection volume of I-sequence holes in the construction area is 559.18 kg / m, and that of II-sequence holes is 392.29 kg / m, decreasing by 30.0%, proving that the skip-hole interval can effectively avoid grout cross-flow and improve the uniformity of foundation reinforcement.

[0021] Example 5: This embodiment, based on the above embodiment, further specifies that in step S5, the grouting construction is carried out in 2 to 4 stages, the specific number of stages being determined according to the geological conditions. For areas with large porosity in the fill soil, 4 stages of grouting are performed; for relatively dense strata, 2 stages of grouting are performed. The duration of each grouting stage is controlled to be 30 to 45 minutes. When the grouting pressure does not rise significantly for 1 to 2 hours, the current grouting is immediately stopped, with an interval of 10 to 20 minutes. The interval time is adjusted according to the ambient temperature: 10 minutes when the temperature is above 25℃, and 20 minutes when the temperature is below 15℃. After the grout has initially solidified and formed a certain strength, the next grouting is carried out. The purpose of staged grouting is to avoid excessive single grouting pressure that could cause ground heave, while ensuring that the grout fully fills the stratum pores. Tests show that this method can reduce the grouting volume per unit solidified layer by 15% to 20%, and the coefficient of variation of foundation compaction is less than 0.07.

[0022] Example 6: This embodiment, based on the above embodiment, further includes step S7: After grouting is completed, quality testing is conducted in stages according to the importance of the reinforced area: the test area is tested 28 days after grouting is completed, and the construction area undergoes self-inspection 7 days after grouting is completed. Testing methods include light dynamic penetration testing and shallow plate load testing. Lightweight dynamic penetration test: using N 10 The penetrometer was used, with the number of testing points not less than 2% to 5% of the number of grouting holes (3 testing points for 20 grouting holes in the test area; 4 testing points for 80 grouting holes in the construction area). The testing depth started from 1m below the ground, and the standard value for the number of hammer blows was not less than 30. The actual test results for the project were: N in the test area. 10 Standard value 45.9 blows, construction area N 10 The standard value is 44.2 hits, which meets the requirements. Shallow plate load test: The bearing plate area is 0.5m², the maximum test load is 40kPa, the settlement of the bearing plate under this load is no more than 5mm, and the p~s curve is flat without abrupt changes. The project test shows that the maximum settlement is 3.14mm, and the characteristic value of the foundation bearing capacity is 20kPa, which meets the design requirements.

[0023] If the pass rate of the test points is less than 80%, the unqualified areas need to be grouted repeatedly until the test passes.

[0024] Example 7: This embodiment, based on the above embodiment, further specifies the details of the sealing operation and subsequent connection after stopping grouting in step S6: After stopping grouting, sealing is performed immediately: using cement mortar with a strength grade not lower than M10, it is injected into the grouting hole in 3-5 portions through the grouting pipe, each injection volume being 1 / 3 to 1 / 2 of the hole volume. After injection, it is left to stand for 5-10 minutes until the mortar naturally settles before the next injection, until the cement mortar no longer settles. After sealing, a 20cm thick layer of compacted soil must be placed over the hole opening to prevent rainwater from seeping into the hole and reducing the mortar strength. Furthermore, the sealing quality must be coordinated with the subsequent road restoration process—the sidewalk road restoration should refer to the sidewalk structure detail drawing in design drawing 423-017-E81-YJLA-BLHL-DL-05, and the non-motorized vehicle road restoration should refer to the non-motorized vehicle lane structure detail drawing in the same drawing, ensuring that the foundation after sealing can withstand the road load.

[0025] Example 8: Based on the above embodiments, this embodiment further specifies that in step S3, the water-cement ratio of the cement paste is determined through phased verification in the project test section: The first stage: Cement grout with a water-cement ratio of 1:1 was mixed with water glass at a weight ratio of 1:1. According to the field test, the grout solidification time was 45 seconds, but the unit solidified grouting volume was 715.16L / m³, and the grouting material consumption was relatively large. Phase 2: The design unit suggested adjusting the water-cement ratio based on the data from the test area. The project technical team conducted comparative experiments and found that when the water-cement ratio was 0.8:1, the density of the cement slurry increased, and the setting time after mixing with water glass at a 1:1 ratio was still 45 seconds. Moreover, the fluidity of the slurry met the requirements for conveying through the sleeve valve pipe. In the third stage, a cement grout with a water-cement ratio of 0.8:1 was used, reducing the grouting volume per unit solidified layer to 359.59 L / m³, a 49% decrease compared to the test area, without affecting the foundation reinforcement effect. Ultimately, a cement grout with a water-cement ratio of 0.8:1 was chosen, balancing reinforcement effectiveness and economy.

[0026] Example 9: Based on the above embodiments, this embodiment further specifies that in step S5, during the grouting construction process, a dedicated person should be arranged to inspect the sewage wells, information wells, road surfaces and underground pipe networks within a 5m radius around the grouting hole, and record the inspection situation every 15 minutes. If grout leakage is found on the ground, the grouting pump should be shut down immediately to stop grouting, and quick-setting cement mortar should be used to seal the grout leakage point. The sealing range should cover the area around the leakage point within 1m, and the thickness should not be less than 5cm. After sealing is completed, allow a 15-20 minute interval to allow the sealing layer to reach a certain strength. Then, restart the grouting pump, reducing the grouting rate to 25-30 L / min and gradually increasing the pressure to 0.5 MPa. Observe whether grout leakage occurs again. If the leakage originates from underground pipeline damage, grouting in that area must be stopped, the location of the pipeline damage investigated and repaired, and then grouting resumed. During the project's trial phase, this process achieved a 100% success rate in handling leakage, without causing damage to the surrounding pipeline network.

[0027] Example 10: Based on the above embodiments, this embodiment further specifies that in step S3, the fineness requirement of ordinary Portland cement is as follows: under normal circumstances, the cement needs to pass through an 80μm square hole sieve with a sieve residue of no more than 5%; when the opening of the box culvert joint is less than 0.5mm (which needs to be determined by on-site measurement), the fineness of the cement is adjusted to pass through a 71μm square hole sieve with a sieve residue of no more than 2%, to ensure that cement particles can pass through the joint gaps and improve the reinforcement effect; Quality Inspection: Each batch of cement must be tested before entering the warehouse, and a quality inspection report including the date of manufacture, chemical composition, fineness, and loss on ignition must be submitted. The cement can only be used after it has been reviewed and approved by the supervision unit. The fineness of the cement will be randomly checked at the construction site every 15 days. Cement that is damp, lumpy, or has excessive fineness must be strictly prohibited from use.

[0028] Example 11: This embodiment, based on the above embodiments, provides a specific engineering example as follows: I. Implementation Background This project example originates from a section of the second phase of the PPP project for the co-construction of sewage treatment plant and ecological water network in the main urban area of ​​a certain city. The stormwater culvert (chainage K0+000~K0+555, BXH=3m×3m, burial depth 5.20~7.66m) and sewage pipeline (chainage K0+400~K0+555, pipe diameter d500~d1200, burial depth 3.13~7.06m) in this section have serious hidden dangers in the surrounding foundation: Pipeline exploration and borehole analysis revealed that the 1.5~2.5m layer is loose mixed fill soil (large pores, high permeability), and the 2.5~6.0m layer is soft soil with localized cavities. During drilling, the drill rod descended rapidly, and there were occasional instances of drill bit falling off, leading to multiple ground subsidences. Therefore, it is necessary to reinforce the foundation through double-liquid grouting to ensure the safety of the pipeline and road.

[0029] II. Scope and Divisions This project follows the principle of "trial first, optimization and promotion," and is divided into two core implementation areas. Specific parameters are as follows: 1. Pilot Zone (First Implementation Zone) Chainage range: K0+308.597~K0+316.097, section length 7.5m, corresponding to the middle area of ​​the stormwater culvert; Reinforcement scope: Reinforcement width 5m (including 2m sidewalk + 3m non-motorized vehicle lane), reinforcement depth 1m below the bottom of the pipe after repair, reinforcement volume approximately 225m³; Hole layout: Four rows of grouting holes are arranged in a quincunx pattern, with a row spacing of 1.2m and a hole spacing of 1.5m×1.5m, for a total of 20 grouting holes (12 holes in sequence I and 8 holes in sequence II).

[0030] Unit 2.9 (Second Implementation Area) Chainage range: K0+254.597~K0+284.597, section length 30m, corresponding to a densely packed section of sewage pipes; Reinforcement scale: The reinforcement width and depth are consistent with the test area, and the reinforcement volume is approximately 900 m³; Hole layout: Same as the plum blossom pattern 4-row hole design, row spacing 1.5m, hole spacing 1.5m×1.5m, a total of 80 grouting holes (40 holes in sequence I and 40 holes in sequence II).

[0031] III. Core Implementation Parameters 1. Grouting material parameters Cement: Three Gorges brand P.O42.5 grade ordinary Portland cement is used, with fineness passing through an 80μm square hole sieve (sieve residue ≤5%), and the time from the date of manufacture ≤90 days; Water glass: modulus 3.1~3.4, Baumé degree 40°Be, specific gravity 1.38, meeting the requirement of slurry setting time of 35~50 seconds. Two-component grout mix proportions: cement to water glass weight ratio 1:1; cement grout water-cement ratio: 1:1 in the test area, optimized to 0.8:1 in unit 9. Water for slurry preparation: conforms to the "Standard for Water for Concrete Mixing" JGJ63-1989, with a water temperature ≤40℃. 2. Construction equipment and process parameters Drilling equipment: XL-50 drilling rig, hole diameter 70~110mm, drilling depth 3~6m (adjusted according to pipeline exploration to ensure that the grouting point cover layer is ≥1.0m). Sleeve valve pipe: a disposable plastic pipe with an inner diameter of 50mm. The grouting section is a perforated pipe with plum blossom-shaped injection holes (1 group every 33cm, 6~8 holes per group). The holes are wrapped with 5~8cm rubber sleeve valves. The non-grouting section is a solid pipe. Grouting process: Pure pressure grouting with sleeve valve tube, grouting pressure 0.5MPa (pressure <0.4~0.5MPa cannot open the small hole of sleeve valve tube), grouting speed 30~35L / min; Final grouting criteria: Cracks / grout leakage / bulging appear on the ground, or the grouting pressure reaches 0.5MPa and the injected volume is basically not absorbed by the grout.

[0032] IV. Detailed Implementation Steps Step 1: Preliminary preparation and layout positioning Based on the construction drawings and the results of on-site pipeline survey, mark the locations of rainwater culverts and sewage pipes, avoiding other underground pipelines such as gas and low-voltage electrical lines; Designed according to a quincunx pattern, the holes were laid out and positioned using a total station, and the hole number and depth requirement were marked at each hole location.

[0033] Step 2: Drilling and Installing the Sleeve Valve Tube The XL-50 drilling rig was used to drill holes according to the marked positions. During the drilling process, the geological conditions were recorded (such as the drilling speed in the fill section and whether the drill bit fell off in the soft soil layer). If a pipeline was encountered, the hole depth was adjusted. After drilling is completed, the sleeve valve pipe is immediately embedded. Cement mortar is poured into the gap between the sleeve valve pipe and the hole wall as a casing material. Let it stand for 24 hours to allow the casing material to solidify, ensuring that the sleeve valve pipe is firmly fixed.

[0034] Step 3: Two-component grouting construction (sequential and staged grouting) Grouting sequence: First construct the outermost row 1 and 4 holes, then construct the innermost row 2 and 3 holes; within the same row, first construct the first sequence holes, and then construct the second sequence holes after a gap of at least one hole (skip hole interval). Grouting in stages: Test area (water-cement ratio 1:1): The fill section was grouted in 4 stages, and the soft soil layer was grouted in 3 stages. Each grouting session lasted 30-45 minutes, with an interval of 10-20 minutes (10 minutes interval for temperatures above 25℃, and 20 minutes interval for temperatures below 15℃). The 9-unit (water-cement ratio 0.8:1) was optimized to grout the miscellaneous fill section in 3 stages and the soft soil layer in 2 stages, reducing material consumption; Process control: Use an automatic recorder to monitor the grouting pressure and grout intake in real time. If grout leakage occurs, stop grouting immediately and manually seal it. Re-grout after an interval.

[0035] Step 4: Final grouting and hole sealing Grouting was stopped when the final grouting criteria were met: the average grouting volume per hole in the test area was 5.24 m³ (4.18 t of cement), and the average grouting volume per hole in the 9 units was 2.48 m³ (2.18 t of cement). After grouting is completed, M10 cement mortar is injected into the grouting hole in 3 to 5 times until the mortar no longer sinks, thus completing the sealing of the hole.

[0036] Step 5: Quality Inspection Lightweight dynamic penetration test: Three points were tested 28 days after grouting in the test area. N 10 The standard value for the number of hammer blows is 45.9; 4 points were tested 7 days after grouting of 9 units, N 10 The standard value for the number of hammer blows is 44.2, all of which are greater than the standard of 30 blows. Shallow plate load test: Tested on November 28, 2022. The bearing plate area is 0.5m². The settlement is 3.14mm when the maximum load is 40kPa. The characteristic value of the foundation bearing capacity is 20kPa, which meets the design requirements.

[0037] V. Implementation Results Foundation reinforcement effect: After grouting, the density of the stratum is significantly improved, the porosity of the miscellaneous fill soil is reduced from 35% to 18%, there are no voids in the soft soil layer, and the risk of ground subsidence is completely eliminated; Economic optimization: After adjusting the water-cement ratio of Unit 9 to 0.8:1, the grouting volume per unit solidified material decreased from 715.16 L / m³ in the test area to 359.59 L / m³, a decrease of 49%, saving cement and water glass usage; Structural safety: The rainwater culvert and sewage pipes were not disturbed by the grouting, and the road was open to traffic normally after the road surface was restored.

[0038] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A two-component grouting construction method for reinforcing the foundation around box culverts and pipelines, characterized in that, Includes the following steps: Step S1: For the foundation around the rainwater culvert and sewage pipe, delineate the reinforcement area, and the reinforcement depth is 1m below the pipe after the pipe repair is completed; Step S2: Arrange the grouting holes in a quincunx pattern, with a hole spacing of 1.5m × 1.5m, for a total of 4 rows of grouting holes, with a row spacing of 1.2m to 1.5m; Step S3: Use a two-component slurry, which is composed of ordinary silicate cement and water glass, with a cement to water glass weight ratio of 1:1 and a cement slurry water-cement ratio of 0.8:

1. Step S4: Drill holes with a diameter of 70mm~110mm and a drilling depth of 3m~6m. After drilling, embed a sleeve valve pipe with an inner diameter of 50mm. The grouting section is a perforated pipe with plum blossom-shaped injection holes, and the non-grouting section is a solid pipe. Wrap the injection holes with 5cm~8cm rubber sleeve valves and pour casing material to fix the sleeve valve pipe. Grouting is carried out 24 hours after the sleeve valve pipe is fixed. Step S5: Use the sleeve valve pipe pure pressure grouting method, control the grouting pressure at 0.5MPa, and the grouting speed at 30L / min~35L / min; the construction sequence is to first construct the outer row 1 and 4 grouting holes, and then construct the inner row 2 and 3 grouting holes. Within the same row, construct the first sequence hole first and then the second sequence hole, using a skip-hole interval construction method. Step S6: Stop grouting when cracks, grout leakage, or ground heave occur on the ground, or when the grouting pressure reaches 0.5MPa and the injection volume is basically not absorbed.

2. The dual-liquid grouting construction method for reinforcing the foundation around box culverts and pipelines according to claim 1, characterized in that, In step S3, the water glass used has a modulus of 3.1 to 3.4, a Baumé degree of 40°Be, and a specific gravity of 1.

38.

3. A two-component grouting construction method for reinforcing the foundation around box culverts and pipelines according to claim 1 or 2, characterized in that, In step S4, the drilling depth is adjusted according to the results of the on-site pipeline network exploration, and the thickness of the overburden layer above the grouting point is not less than 1.0m.

4. A two-component grouting construction method for reinforcing the foundation around box culverts and pipelines according to claim 1 or 2, characterized in that, In step S5, the specific method of skip-hole interval construction is as follows: after the construction of adjacent I sequence holes in the same row is completed, II sequence holes are constructed after a gap of at least 1 hole position.

5. A two-component grouting construction method for reinforcing the foundation around box culverts and pipelines according to claim 1 or 2, characterized in that, In step S5, the grouting is carried out in 2 to 4 stages, with an interval of 10 to 20 minutes after each grouting, until the final grouting standard is met.

6. A two-component grouting construction method for reinforcing the foundation around box culverts and pipelines according to claim 1 or 2, characterized in that, It also includes step S7: quality inspection is carried out within 7-28 days after grouting, and the inspection methods include light dynamic penetration testing and shallow plate load testing; among which, the N of light dynamic penetration testing... 10 The standard value for the number of hammer blows shall not be less than 30 blows, and the characteristic value of the foundation bearing capacity measured by the shallow plate load test shall not be less than 20 kPa.

7. A two-component grouting construction method for reinforcing the foundation around box culverts and pipelines according to claim 1 or 2, characterized in that, After stopping grouting in step S6, a sealing step is also included, which involves injecting cement mortar into the grouting hole multiple times until the cement mortar no longer settles.

8. A two-component grouting construction method for reinforcing the foundation around box culverts and pipelines according to claim 1 or 2, characterized in that, In step S3, the water-cement ratio of the cement grout is determined through test section verification: when the test section uses a water-cement ratio of 1:1, if the unit grouting volume is too large, it is adjusted to 0.8:1 to reduce the grouting volume per unit solidified body.

9. A two-component grouting construction method for reinforcing the foundation around box culverts and pipelines according to claim 1 or 2, characterized in that, In step S5, if grout leakage occurs on the ground during the grouting process, grouting should be stopped immediately, the leakage outlets should be manually sealed, and after a period of time, grouting should be resumed until the final grouting standard is met.

10. A two-component grouting construction method for reinforcing the foundation around box culverts and pipelines according to claim 1 or 2, characterized in that, In step S3, the fineness requirement for ordinary Portland cement is: passing through an 80μm square hole sieve with a sieve residue of no more than 5%; when the opening of the box culvert joint is less than 0.5mm, the fineness of the cement is adjusted to pass through a 71μm square hole sieve with a sieve residue of no more than 2%.

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