Indoor evaluation method for road disease trenchless grouting repair effect

Abstract

The invention relates to an indoor evaluation method for a road disease trenchless grouting repair effect. The indoor evaluation method comprises the following steps: S1, preparing a road structure model: paving and compacting a road base material and a road surface material; s2, disease simulation: manually intervening and simulating cavity and loose diseases of the road; s3, indoor grouting repair is conducted, specifically, grouting holes are formed in the road surface layer, and grouting maintenance is conducted; s4, repairing effect evaluation: carrying out unconfined compressive strength and asphalt freeze-thaw splitting tests on the repairing core sample; according to the indoor evaluation method, the process is standardized and does not depend on uncontrollable field environment and experience judgment, the key data of the repaired structure is obtained by objectively performing mechanical property test on the repaired core sample, a theoretical basis is provided for grouting material development and construction process parameter determination, the blindness and risk of engineering application are reduced, and the construction efficiency is improved. And the technology is promoted to develop to standardization and refinement.

Description

Technical Field

[0001] This invention belongs to the field of deep road disease prevention and control technology, specifically relating to an indoor evaluation method for the effect of trenchless grouting repair of road diseases. Background Technology

[0002] With the continuous improvement of my country's highway network and the sustained growth of traffic load, road structures are prone to developing deep-seated, hidden defects during long-term service due to the combined effects of multiple factors such as vehicle dynamic loads, environmental erosion, and material aging. These defects are located in the lower layers of the pavement structure, such as the base course, subbase course, and even the top of the subgrade. They are not easily detected in the early stages, but they will significantly weaken the overall load-bearing capacity and service life of the road.

[0003] Common types of deep road defects include: voids and cavities: often occurring between the base course and surface course, or within the base course, due to material loss or compaction settlement forming cavities, causing the surface course to lose effective support; loose and fragmented base course: manifested as failure of the binder, loss of interlocking force between aggregates, and destruction of the overall structure; subsidence and uneven settlement: usually caused by soft and compressive deformation of the subgrade, leading to changes in the road alignment; and downward extension of structural cracks: surface cracks develop into deeper layers, becoming channels for water and impurities to invade, accelerating structural deterioration.

[0004] Accurate identification and assessment of these deep-seated defects are prerequisites for effective remediation. Currently, detection technologies for deep-seated defects include non-destructive testing, such as falling weight deflectometers, which calculate the structural layer modulus by measuring the deflection basin and can indirectly identify weak areas, but struggle to accurately depict the spatial morphology and severity of the defects. Ground-penetrating radar (GPR), by emitting electromagnetic waves and receiving reflected signals, can identify anomalous stratigraphic interfaces and obvious cavities, but its detection depth and resolution are significantly affected by the electrical properties of the medium, it is prone to false positives in water-bearing areas, and it is not sensitive enough to non-obvious cavity-type defects such as loosening and strength attenuation. Acoustic wave detection and impact echo detection technologies also have similar problems; the accuracy of their results is highly dependent on the experience of the interpreters.

[0005] The limitations of existing testing technologies directly lead to difficulties in evaluating the effectiveness of trenchless grouting repair. Currently, the evaluation of grouting repair effectiveness in engineering practice largely relies on the post-repair pavement appearance, short-term follow-up observations after traffic resumption, or re-testing of deflection. These methods are all "post-hoc" and "indirect" evaluations, unable to accurately and quantitatively predict and assess the repair efficacy of the interaction between the grouting material and the damaged area in an indoor or pre-construction environment. Specifically, existing technologies lack standardized testing methods and evaluation systems that can effectively simulate deep road defects such as cavities and loose structures, and systematically evaluate the filling density, restoration of structural integrity, and improvement of mechanical strength and durability of grouting materials in an indoor environment. This results in a lack of targeted feedback in the design optimization of grouting materials, and the determination of grouting process parameters largely depends on engineering experience rather than scientific experimental data, ultimately restricting the reliable application and further development of trenchless grouting repair technology in the treatment of deep road defects.

[0006] Therefore, developing a scientific, systematic method that can simulate and quantify the effects of trenchless grouting repair indoors has become an urgent need to improve the quality of deep road damage repair and promote the standardized application of trenchless technology. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention proposes an indoor evaluation method for the effectiveness of trenchless grouting repair of road defects.

[0008] The technical solution of this invention is as follows: An indoor evaluation method for the effectiveness of trenchless grouting repair of road defects includes the following steps: S1. Road structure model preparation: The base layer material and the surface layer material are laid and compacted in sequence to obtain the road structure model; S2. Road Defect Simulation: The road structure model is artificially intervened to simulate at least one of the following defects: voids and loose structure. S3. Indoor grouting repair: Grouting holes are set on the surface of the surface material of the disease model, and grouting material is used to simulate grouting construction and then curing is performed; S4. Evaluation of Repair Effect: Core samples are taken from the road model after grouting repair, and the performance of the obtained core samples is tested. The grouting repair effect is evaluated based on the test results.

[0009] Further, in step S1, the base material is a cement-stabilized crushed stone base with a paving thickness of 16-20 cm; the surface material is an asphalt mixture surface with a paving thickness of 6-10 cm.

[0010] Furthermore, the cement-stabilized crushed stone base course comprises aggregates and silicate cement, wherein the silicate cement accounts for 4% of the total mass of the aggregates, and the aggregates comprise coarse aggregates and fine aggregates. By mass percentage, the coarse aggregates account for 73% and the fine aggregates account for 27%, wherein the coarse aggregates comprise 51% of 10-26.5mm aggregates and 22% of 5-10mm aggregates, and the moisture content of the cement-stabilized crushed stone base course is 5.2%.

[0011] Furthermore, in step S1, before the surface material is laid, an emulsified asphalt bonding layer is applied to the surface of the laid and compacted base material.

[0012] Furthermore, in step S2, the simulation of the structural loosening disease is achieved by controlling the compaction degree of the cement-stabilized crushed stone base layer to be 80-90%.

[0013] Furthermore, in step S2, the simulation of the road cavity defect is achieved by drilling holes from the side of the road model and removing the internal material to form a cavity that accounts for 1-5% of the volume of the road model.

[0014] Furthermore, the arrangement of the grouting holes in step S3 is as follows: the horizontal and vertical spacing between the grouting holes is 150-350 mm.

[0015] Further, by weight, the grouting material in step S3 includes the following raw materials: 70-90 parts of sulfoaluminate cement, 10-30 parts of silicate cement, 3-7 parts of silica fume, 5-15 parts of mineral powder, 5-15 parts of fly ash, 0.3-0.7 parts of naphthalene-based water-reducing agent, and 0.05-0.15 parts of sulfoaluminate retarder.

[0016] Compared with the prior art, the present invention has at least the following advantages: This invention relates to an indoor evaluation method for the effectiveness of trenchless grouting repair of road defects, comprising steps of road structure model preparation, defect simulation, indoor grouting repair, and repair effect evaluation. The indoor evaluation method standardizes the process, does not rely on uncontrollable field environments and experience-based judgments, and objectively obtains key data of the repaired structure by conducting mechanical property tests on the repaired core samples. This provides a theoretical basis for the development of grouting materials and the determination of construction process parameters, reduces the blindness and risk of engineering applications, and promotes the standardization and refinement of technology. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below.

[0018] Figure 1 This is a schematic diagram of a road structure model according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the grouting hole layout in Embodiment 3 of the present invention. Detailed Implementation

[0019] The present invention will now be described in further detail. It should be noted that the following specific embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above application content.

[0020] This invention provides a general and / or specific description of the materials and experimental methods used in the experiments. Unless otherwise specified, all experimental or testing methods are conventional methods; all reagents or instruments used, unless otherwise specified, are commercially available conventional products prepared or used using conventional methods.

[0021] Source of materials Sulfoaluminate cement: SAC, grade 42.5, Dengdian Group Cement Co., Ltd.; Silicate cement: PO, grade 42.5, Huaxin Cement Co., Ltd.; Silica fume: Highly active microsilica powder, with performance indicators meeting the standard GB / T 18736-2017 "Mineral Admixtures for High-Strength and High-Performance Concrete"; Mineral powder: S95 grade blast furnace slag powder, with performance indicators meeting the standard GB / T 18046-2017 "Granulated blast furnace slag powder for use in cement, mortar and concrete"; Fly ash: Grade I fly ash, with performance indicators meeting the standard GB / T 1596-2017 "Fly ash for use in cement and concrete"; Naphthalene-based water-reducing agent: purchased from Shandong Yousuo Chemical Technology Co., Ltd.; Sulfoaluminate retarder: purchased from Shanxi Feike New Material Technology Co., Ltd.

[0022] Example 1: Road Defect Simulation S1. Preparation of Road Structure Model The road model structure includes a cement-stabilized crushed stone base course and an asphalt mixture surface course. According to the "Technical Specifications for Construction of Highway Pavement Base Course (JTGT-F20-2015)," the thickness of each layer after compaction should not be less than 160mm and not more than 200mm. In this embodiment, a 20cm cement-stabilized crushed stone base course is used, with an 8cm layer of AC-13 asphalt mixture laid on the surface. Rigid plastic boxes are used as formwork to support the aggregate. The dimensions of the boxes are length × width × height = 58cm × 40cm × 32cm. The road model structure is as follows: Figure 1 As shown.

[0023] S11. Installation of Cement-Stabilized Crushed Stone Base Course: The aggregate of the cement-stabilized crushed stone base course includes coarse aggregate and fine aggregate. The coarse aggregate is limestone aggregate, divided into two grades: 10-26.5mm and 5-10mm, with mass ratios of 51% and 22% respectively. The fine aggregate is manufactured sand, with a mass ratio of 27%. The cementing material is PO 42.5 grade ordinary Portland cement, with a cement content of 4% of the total aggregate mass. Water accounts for 5.2% of the total aggregate mass, and the maximum dry density is 2.1328 g / cm³. 3 (The moisture content and maximum dry density are determined by the Class C compaction method specified in the "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" (JTG E51-2009); After mixing the dried aggregates according to the proportion, cement and water are added, and the mixture is mixed evenly with a concrete mixer to obtain the mixture. The mixed mixture is then placed in a rigid plastic box and spread evenly. To simulate loosening disease, the mixture is divided into an experimental group and a control group. The experimental group has a designated area of ​​30×30cm as the loosening disease simulation area. The compaction degree of the loosening disease simulation area is 85%, and the compaction degree of the non-simulated area is 95%. The compaction degree of the cement-stabilized crushed stone base in the control group is 95%. The mixture is compacted using a rutting tester until the base thickness reaches 20cm. After molding, it is cured for 7 days to ensure cement hydration.

[0024] S12. Paving of the Surface Asphalt Mixture: After the cement-stabilized crushed stone base course is cured, the road surface asphalt mixture is laid. The surface layer uses AC-13 type asphalt mixture, employing limestone aggregate and SBS modified asphalt, with an asphalt content of 4.7%. To ensure good bonding between the base course and the surface layer, emulsified asphalt is first evenly applied as a bonding layer to the surface of the cured cement-stabilized crushed stone layer, with an emulsified asphalt application rate of 1 kg / m². 2 The asphalt mixture is thoroughly mixed in a mixing pot at a mixing temperature of 165℃, and then spread in multiple stages onto the prepared base course. After each paving, a rutting tester is used for compaction to ensure the density and thickness of the mixture are uniform. The final paving thickness is controlled at 8cm.

[0025] S13. Road Defect Simulation Model: The road model formed in step S12 is used as the control group. At the same time, two experimental groups are set up based on it: a road cavity defect simulation model and a road loose defect simulation model.

[0026] S131. Simulation Model of Road Cavity Defect: In this embodiment, a 20mm drill is used to drill horizontally from the side of the model, 10cm from the top surface, gradually removing part of the cement-stabilized crushed stone upper base layer and the asphalt mixture lower layer material, forming an approximately ellipsoidal internal cavity with a volume of 2000cm³. 3 about; S132. Road loosening disease simulation model: See the preparation method of loosening disease simulation model in step S11.

[0027] Example 2: Preparation method of modified cement-based grouting material By weight: 80 parts of sulfoaluminate cement, 20 parts of silicate cement, 5.01 parts of silica fume, 11.48 parts of mineral powder, 8.36 parts of fly ash, 0.5 parts of naphthalene-based water-reducing agent, and 0.1 parts of sulfoaluminate retarder; then, add all the weighed sulfoaluminate cement, silicate cement, silica fume, mineral powder, and fly ash into a cement paste mixer for dry mixing, stirring continuously at 120 r / min for 5 minutes until all powder components are uniformly mixed; then, dissolve the water-reducing agent and retarder together in 0.35 times the total amount of water in the formula to prepare a crosslinking aqueous solution; the mixer continues to run, and the crosslinking aqueous solution is poured into the mixed dry powder at a uniform speed within 2 minutes, the mixer speed is increased to 240 r / min, and high-speed mixing is continued for 3 minutes to obtain modified cement-based grouting slurry for subsequent indoor simulated grouting repair tests.

[0028] Example 3: Indoor Simulated Grouting Repair S1. Grouting Hole Layout: 16 mm grouting heads are selected, and the horizontal and vertical spacing of the grouting holes is 150 mm. Figure 2 As shown; S2. Grouting: Using an M16 high-pressure grouting machine, the modified cement-based grouting material prepared in Example 2 was injected into the affected area at a pressure of 4 MPa, with a grouting rate of approximately 1 kg / min. Grouting was stopped when grout was observed overflowing from adjacent holes or the surface of the model. S3. Sealing and curing: After grouting is completed, quickly pull out the grouting head and seal the grouting hole with a plug, remove any residual grout from the surface, and cure the repaired model under standard conditions for 14 days.

[0029] Example 4: Sampling and Evaluation of Repair Effect S1. Core Sampling: After the curing is completed, a core drill with a diameter of 100 mm is used to drill core samples from the grouting repair area to obtain complete cylindrical core samples. The cavities in the core samples have been densely filled with grouting material.

[0030] S2. Test Method: S21. For the road cavity disease simulation model prepared in step S131 of the repaired embodiment, an unconfined compressive strength test was conducted: the core sample was cut into standard cylindrical specimens with a diameter and height of 100 mm, and an unconfined compressive strength test was conducted using a universal press. The test results are shown in Table 1.

[0031] Table 1. Experimental data on unconfined compressive strength As shown in Table 1, the unconfined compressive strength of the unrepaired core samples simulating road cavities through artificial drilling was relatively low. After 7 days of grouting repair, the compressive strength was 5.1 MPa, which was 86.4% of the strength of the intact core sample. As the curing time was extended to 14 days, the compressive strength of the core sample repaired with grouting material reached 5.9 MPa, which was 89.4% of the strength of the intact core sample. The strength of the repaired core samples all met the unconfined compressive strength standard, indicating that cement-based grouting materials have a significant effect on road repair.

[0032] S22. For the road loosening disease simulation model prepared in step S132 of Example 1 after repair, a freeze-thaw splitting test was conducted: Core samples with a diameter of 100 mm were drilled. Referring to the requirements of JTG E20-2011, the cement-stabilized crushed stone base layer at the bottom of the core sample was retained. The core sample was cut into specimens with a height of 63.5 mm ± 1.3 mm. The splitting strength was measured using a Marshall stability tester, and the freeze-thaw splitting strength ratio (TSR) was calculated. The tested asphalt freeze-thaw splitting strengths are shown in Table 2. Table 2. Experimental data on freeze-thaw splitting strength As shown in Table 2, the freeze-thaw splitting strength ratio of the unrepaired core sample was only 57.0%, indicating a significant decrease in splitting strength after freeze-thaw cycles. This suggests that the strength of roads with defects decreases rapidly due to environmental factors. The strength ratios of the grout-repaired core sample and the control group were both greater than the standard. The grout-repaired core sample had the highest freeze-thaw splitting strength ratio at 95.8%, and its splitting strength after freeze-thaw was greater than that of the intact core sample, with a strength loss of only 4.2%. This may be due to the rapid early hydration rate and concentrated heat of sulfoaluminate cement, resulting in strong freeze-thaw resistance. Repair not only enhanced the splitting strength but also improved the freeze-thaw resistance.

[0033] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. An indoor evaluation method for the effectiveness of trenchless grouting repair of road defects, characterized in that, Includes the following steps: S1. Road structure model preparation: The base layer material and the surface layer material are laid and compacted in sequence to obtain the road structure model; S2. Road Defect Simulation: The road structure model is artificially intervened to simulate at least one of the following defects: road voids and structural loosening. S3. Indoor grouting repair: Grouting holes are set on the surface of the surface material of the disease model, and grouting material is used to simulate grouting construction and then curing is performed; S4. Evaluation of Repair Effect: Core samples are taken from the road model after grouting repair, and the performance of the obtained core samples is tested. The grouting repair effect is evaluated based on the test results.

2. The indoor evaluation method according to claim 1, characterized in that, In step S1, the base material is a cement-stabilized crushed stone base with a paving thickness of 16-20 cm; the surface material is an asphalt mixture surface with a paving thickness of 6-10 cm.

3. The indoor evaluation method according to claim 2, characterized in that, The cement-stabilized crushed stone base course comprises aggregates and silicate cement, wherein the silicate cement accounts for 4% of the total mass of the aggregates, and the aggregates include coarse aggregates and fine aggregates. By mass percentage, the coarse aggregates account for 73% and the fine aggregates account for 27%, wherein the coarse aggregates include 51% 10-26.5mm aggregates and 22% 5-10mm aggregates, and the moisture content of the cement-stabilized crushed stone base course is 5.2%.

4. The indoor evaluation method according to claim 2, characterized in that, In step S1, before the surface material is laid, an emulsified asphalt bonding layer is applied to the surface of the laid and compacted base material.

5. The indoor evaluation method according to any one of claims 1-4, characterized in that, In step S2, the simulation of the structural loosening disease is achieved by controlling the compaction degree of the cement-stabilized crushed stone base layer to be 80-90%.

6. The indoor evaluation method according to any one of claims 1-4, characterized in that, In step S2, the road cavity defect is simulated by drilling holes in the side of the road model and removing the internal material to form a cavity that is 1-5% of the volume of the road model.

7. The indoor evaluation method according to claim 1, characterized in that, The specific arrangement of the grouting holes in step S3 is as follows: the horizontal and vertical spacing between the grouting holes is 150-350 mm.

8. The indoor evaluation method according to claim 1, characterized in that, By weight, the grouting material in step S3 includes the following raw materials: 70-90 parts of sulfoaluminate cement, 10-30 parts of silicate cement, 3-7 parts of silica fume, 5-15 parts of mineral powder, 5-15 parts of fly ash, 0.3-0.7 parts of naphthalene-based water-reducing agent, and 0.05-0.15 parts of sulfoaluminate retarder.

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