Existing building terrace reinforcing method

Abstract

The invention belongs to the technical field of building construction, and particularly provides an existing building terrace reinforcing method which comprises the following steps: designing grouting holes; the corresponding relation between the deformation parameters of the foundation soil layer before grouting and the specific penetration resistance is established; the sleeve valve pipes are adopted for grouting the grouting holes in a segmented mode; dynamically adjusting sleeve valve pipe grouting parameters until single-hole grouting is finished according to grouting pressure, flow, slurry diffusion radius and earth surface deformation in the grouting process; and after grouting of all the grouting holes is finished, the specific penetration resistance value of each soil layer is obtained, the deformation parameter of the foundation subjected to grouting reinforcement is obtained according to the corresponding relation between the deformation parameter and the specific penetration resistance, and whether reinforcement construction reaches the standard or not is judged according to the specific penetration resistance value and the deformation parameter. According to the method, the bearing capacity and stability of the composite foundation are improved, consolidation settlement is reduced, sleeve valve pipe grouting parameters are dynamically optimized, cost is saved, and the construction effect is improved.

Description

Technical Field

[0001] This invention belongs to the field of building construction technology, specifically relating to a method for reinforcing the floor of existing buildings. Background Technology

[0002] Some existing buildings have subsurface soil layers consisting of plain fill, fine sand, silty clay, silty clay, and coarse sand. Over time, these layers are prone to deformation. For example, in automated warehouses, the initial floor reinforcement with crushed stone piles has limited effectiveness. With prolonged use, excessive floor deformation can affect the normal operation of shelving and stacker-reclaimers. Furthermore, the floor continues to settle after shelving is loaded, necessitating floor reinforcement. Traditional grouting parameters rely on the experience of multiple workers. The pressure, flow rate, and mix ratio of sleeve valve grouting are all manually set. Due to the complex composition of the subsurface fill layers, changes in geological conditions can easily lead to insufficient grouting, resulting in reinforcement failure, or excessive grouting, causing floor uplift. The grouting effect is difficult to control. Moreover, existing sensors only monitor a single parameter and cannot predict grout diffusion in real time, resulting in delayed feedback. The significant difference in grout absorption capacity between weak and dense layers makes dynamic manual adjustment difficult, leading to poor overall uniformity. Summary of the Invention

[0003] The purpose of this invention is to overcome the problems in the existing technology, such as the complex composition of the backfill layer under the ground, the reliance on workers' experience in existing grouting, the lag in feedback of monitoring parameters, the difficulty in dynamic adjustment by humans, and the difficulty in controlling the grouting effect.

[0004] Therefore, the present invention provides a method for reinforcing the ground of existing buildings, comprising the following steps:

[0005] Design grouting holes;

[0006] Establish the relationship between the deformation parameters of the foundation soil layer before grouting and the specific penetration resistance;

[0007] Grouting is performed in sections into the grouting hole using a sleeve valve pipe;

[0008] Based on the grouting pressure, flow rate, grout diffusion radius, and surface deformation during the grouting process, the grouting parameters of the sleeve valve pipe are dynamically adjusted until the grouting of a single hole is completed.

[0009] After all grouting holes have been filled, the specific penetration resistance value of each soil layer is obtained. Based on the correspondence between deformation parameters and specific penetration resistance, the deformation parameters of the foundation after grouting reinforcement are obtained. The specific penetration resistance value and deformation parameters are used to determine whether the reinforcement construction meets the standards.

[0010] Specifically, the aforementioned grouting holes include vertical grouting holes and inclined grouting holes; the inclined grouting holes are arranged intersectingly between horizontally adjacent vertical grouting holes to form a three-dimensional grouting network.

[0011] Specifically, the tilt angle of the aforementioned inclined grouting hole is 20°.

[0012] Specifically, the above-mentioned establishment of the correspondence between the deformation parameters of the foundation soil layer before grouting and the specific penetration resistance includes: recording the specific penetration resistance Ps through static penetration tests; obtaining the deformation parameters of the foundation soil layer through supplementary drilling, including the compression modulus Es and the deformation modulus E0; and establishing the formula between the deformation parameter E0 / Es and the specific penetration resistance Ps.

[0013] Specifically, the above-mentioned segmented grouting into the grouting hole using sleeve valve pipe includes: drilling a hole after adjusting the verticality of the drilling rig, with the hole diameter larger than the outer diameter of the sleeve valve pipe; cutting sleeve valve pipes of corresponding length according to the hole depth and connecting them section by section; placing the sleeve valve pipe into the center of the hole; filling the annular space between the sleeve valve pipe and the hole wall with casing material and curing it; connecting the outlet of the grouting pump to the top interface of the sleeve valve pipe; preparing the grout according to the design ratio and grouting in a bottom-up, segmented lifting manner.

[0014] Specifically, the above-mentioned dynamic adjustment of sleeve valve grouting parameters includes: real-time monitoring of pressure, flow rate, ground deformation, and grout diffusion radius during the grouting process, establishing trend curves of their changes with preset parameters over time, and adjusting the corresponding parameters according to the cause of the deviation if abnormal data characteristics occur.

[0015] Specifically, the adjustments to the corresponding parameters based on the cause of the deviation include:

[0016] When the pressure increases, the flow rate decreases, and the surface deformation does not change significantly, grouting is suspended, and after reverse flushing, the grouting pressure is reduced while the flow rate remains unchanged.

[0017] When the pressure drops and the flow rate increases, increase the grout concentration, reduce the flow rate, and use intermittent grouting.

[0018] If the ground heave exceeds the standard, grouting should be suspended and the grouting pressure reduced after the pressure dissipates.

[0019] If the grout diffusion radius is insufficient, increase the grouting volume and extend the grouting time for that section.

[0020] When the grout diffusion radius exceeds the standard and the surface deformation in the adjacent area increases, the flow rate should be reduced and intermittent grouting should be adopted to control the diffusion boundary.

[0021] Specifically, the above-mentioned single-hole grouting termination conditions are that the grouting volume reaches 1 to 1.2 times the preset value, and the pressure remains stable at the preset value for 5 to 10 minutes.

[0022] Specifically, the steps for obtaining the deformation parameters of the foundation after grouting reinforcement include: conducting static cone penetration tests on the foundation 14 and 28 days after grouting, obtaining the specific penetration resistance Ps value of each soil layer, and comparing the established relationship between deformation parameters and specific penetration resistance to obtain the deformation parameters of the foundation after grouting reinforcement.

[0023] Specifically, the criteria for judging whether the above-mentioned reinforcement construction meets the standards include: the increase rate of penetration resistance before and after grouting is ≥40%; and the ratio of deformation parameters after grouting to deformation parameters before grouting is ≥1.5.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0025] 1. The method for reinforcing existing building foundations provided by this invention does not require alteration to the existing building layout. It utilizes a sleeve valve pipe to inject grout into the soil between existing crushed stone piles in layers, ensuring that the cement grout can be injected into the fill layer, fine sand layer, and silty clay layer beneath the foundation, thus compacting, permeating, and reinforcing each soil layer. By filling the voids between soil particles with cement particles and lumps, the consolidation compression space of the soil is greatly reduced. This not only improves and reinforces the soil between existing crushed stone piles but also indirectly improves the strength and deformation modulus of the crushed stone piles, forming a binary composite foundation combining crushed stone piles and grouting. This enhances the bearing capacity and stability of the composite foundation and reduces consolidation settlement.

[0026] 2. The existing building foundation reinforcement method provided by this invention employs a three-dimensional grouting network combining vertical and inclined grouting, forming a dual improvement mechanism of void filling and cementation strengthening. Cement grout precisely fills the original pores in the soil and the cracks in the gravel piles. Combined with dynamic control of grouting parameters via sleeve valve pipes, by controlling the water-cement ratio and grouting pressure, cement crystals form a three-dimensional network cemented structure between soil particles, significantly improving the integrity of the binary system and achieving three-dimensional foundation reinforcement. The inclined grouting pipe can penetrate the layered structure of the weak soil between gravel piles, forming a spatially intersecting cement-stone network, which is impossible with traditional single vertical grouting. It can also reinforce the stress center area within existing buildings, ensuring full coverage of the reinforced area and uniform foundation settlement.

[0027] 3. The existing building floor reinforcement method provided by this invention dynamically optimizes the grouting parameters of the sleeve valve pipe by deploying pressure, flow, floor deformation, and ground-penetrating radar sensors, reducing the influence of differences in human experience. The measured grouting uniformity is improved by more than 20%, and the material waste rate is reduced from 15% to less than 5%. It can adapt to complex strata such as sand / clay interlayers.

[0028] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a composite foundation structure constructed using an existing building floor reinforcement method in one implementation method.

[0030] Figure 2 This is a schematic diagram of the planar arrangement of grouting holes under a single row of shelves in one implementation method.

[0031] Figure 3 This is a cross-sectional view of the horizontal grouting under a single row of shelves in one implementation method.

[0032] Figure 4 This is a schematic diagram of the planar arrangement of grouting holes under a double-row shelf in one implementation method.

[0033] Figure 5 This is a cross-sectional view of the horizontal grouting under a double-row shelf in one implementation method.

[0034] Figure 6 This is a longitudinal grouting cross-section diagram under the shelf in one implementation method.

[0035] Figure 7 This is a schematic diagram of grouting through a sleeve valve pipe in one implementation method.

[0036] Attached reference numerals: 1. Crushed stone pile; 2. Grouting hole; 3. Vertical pile; 4. Inclined pile; 5. Single row rack; 6. Double row rack; 7. Backfill layer; 8. Fine sand layer; 9. Silt-like silty clay layer; 10. Sleeve valve pipe; 11. Grouting slurry. Detailed Implementation

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Although representative embodiments of the present invention have been described in detail, those skilled in the art will understand that various modifications and changes can be made to the present invention without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the embodiments, but should be defined by the appended claims and their equivalents.

[0038] This invention provides a method for reinforcing the floor of existing buildings, comprising the following steps:

[0039] S1. Based on the layout of the existing building and the penetration radius of the grout and the distribution of the foundation soil layers, design the spacing and depth of the grouting holes for the soil between the existing crushed stone piles.

[0040] Taking automated warehouses as an example, the specific design principles are as follows:

[0041] S101, Principles for the Layout of Holes for Shelf Support Beams

[0042] Based on the load-bearing distribution and structural layout of the rack support beams in the warehouse, a strategy of denser holes under the beams and balanced holes in the mid-span is adopted. Main reinforcement holes are arranged at intervals along the axis of the support beams, and auxiliary holes are added at the support points of the support beams and in the stress concentration areas in the mid-span to ensure precise coupling between the grouting reinforcement area and the load transfer path of the racks.

[0043] Reference Figure 2-6For single-row shelving, vertical grouting is used under the grouting holes to form multiple rows of parallel vertical piles. For double-row shelving, vertical grouting is combined with inclined grouting. The inclined grouting holes are arranged intersecting between the adjacent vertical grouting holes in the horizontal direction of the shelving, with an optimal inclination angle of 20°. The vertical piles and inclined piles form a three-dimensional network, fully filling the voids in the soil, strengthening the bond, and improving the load-bearing capacity. The specific number of rows and the number of holes per row are designed according to the actual situation.

[0044] S102, Coupled Design of Permeability Radius and Soil Depth

[0045] The effective penetration radius of the grout was determined by on-site grouting tests. The hole spacing was designed based on the effective penetration radius of the grout to ensure that the grout diffusion zones of adjacent holes overlapped and the reinforcement layer was continuous.

[0046] By pre-scanning the distribution of the foundation soil layers under the ground surface using ground-penetrating radar, the corresponding hole depth is designed based on the soil layer thickness and the ultra-deep grouting.

[0047] S2. Before grouting, static penetration tests and supplementary drilling are conducted to establish the relationship between the deformation parameters of the foundation soil layer and the specific penetration resistance before grouting.

[0048] S201. Conduct static cone penetration tests (CPT).

[0049] Static cone penetration test boreholes are arranged at intervals around the perimeter and inside the building to be reinforced, preferably in the middle of two adjacent grouting boreholes, and should be staggered from the grouting boreholes by ≥1.0m to avoid mutual interference. The borehole depth should exceed the thickness of the foundation compressible layer. Four in-situ static cone penetration tests are conducted in each test area before grouting. The data acquisition interval for each borehole is ≤20cm to ensure the continuity of soil parameters.

[0050] Record the depth-specific penetration resistance (Ps) curve.

[0051] S202, Conduct supplementary drilling.

[0052] The drilling site should coincide with or be adjacent to the static cone penetration test site (≤2m) to ensure data comparability; the drilling depth should be ≥ the static cone penetration test depth, and undisturbed soil samples should be taken for indoor testing to determine physical properties such as soil moisture content, density, and void ratio.

[0053] The compression modulus Es is obtained through compression testing; the deformation modulus E0 is obtained through load testing.

[0054] S203, Data Comparison and Relationship Establishment

[0055] The Ps curves obtained from static cone penetration tests are matched with the geological profiles of the boreholes to ensure data matching for the same soil layer.

[0056] For each soil layer, the average value of static probe Ps (Ps_avg) and the average value of drilling Es / E0 were extracted. The deformation parameter E0 / Es and the specific penetration resistance Ps formula for the site were established. The formula was verified using other borehole data that were not involved in the modeling, and the error was controlled within ±15%.

[0057] S3. Use sleeve valve pipes to inject grout into the grouting hole in sections, and deploy pressure, flow rate, ground deformation, and ground radar sensors to collect grouting pressure, flow rate, grout diffusion radius, and surface deformation.

[0058] S301, sleeve valve pipe construction

[0059] After the drilling rig is in place, adjust its verticality. Drill using either clean water or mud for wall protection. For soft formations, prioritize mud wall protection to prevent borehole collapse. The borehole diameter should be 50-150mm larger than the outer diameter of the sleeve valve pipe, preferably 110-150mm. Record changes in the formation in real time during drilling and verify consistency with the exploration report. If any unidentified obstacles or sudden changes in formation are encountered, stop drilling immediately and adjust the borehole position or depth. The same inlet can be used when drilling vertical and inclined grouting holes.

[0060] After drilling to the designed depth, the borehole is cleaned by flushing the borehole walls with high-pressure water to remove sediment and mud, ensuring that the sediment thickness at the bottom of the borehole is ≤10cm. After cleaning, the water level in the borehole is maintained to prevent collapse and to create conditions for subsequent sleeve valve installation.

[0061] The sleeve valve tube must be installed to ensure it is centered and securely fixed within the borehole, providing a reliable channel for segmented grouting. Cut sleeve valve tubes to the appropriate length according to the borehole depth and connect them section by section. During installation, slowly lower the sleeve valve tube into the center of the borehole, leaving a 10-20cm gap between the bottom of the tube and the bottom of the borehole to prevent clogging by sediment. The top of the tube should extend 30-50cm above the ground for easy connection to the grouting pipeline. To prevent the sleeve valve tube from shifting, positioning rings with a diameter smaller than the borehole diameter can be installed at intervals of 2-3m along the tube.

[0062] After installation, fill the annular space between the sleeve valve pipe and the hole wall with casing material. When filling, use a bottom-up grouting method to inject the casing material into the bottom of the hole, gradually replacing the clean water in the hole, to ensure that the casing material is fully filled without voids, and that the top surface is 20-30cm below the ground surface to avoid contamination.

[0063] After the casing material is filled, allow it to cure statically until its strength reaches 0.3~0.5MPa. During the curing period, do not disturb the sleeve valve pipe and the surrounding area. Regularly spray water to keep the orifice moist and ensure that the casing material's strength increases evenly.

[0064] S302. Grouting equipment commissioning and grout preparation

[0065] Before grouting, equipment debugging and grout preparation must be completed to ensure a stable and controllable grouting process. First, connect the grouting pump outlet to the top interface of the sleeve valve pipe through a high-pressure hose and check the pipeline sealing. At the same time, start the grout mixer and prepare the grout according to the design ratio. After the grout preparation is completed, filter it through a filter screen and send it to the grout storage tank of the grouting pump to avoid impurities clogging the pipeline or the grouting hole of the sleeve valve pipe.

[0066] S303, Sensor Deployment

[0067] A pressure sensor and a flow sensor are installed at the grouting port end of the sleeve valve pipe to collect the grouting pressure P and flow rate Q in real time.

[0068] Ground deformation sensor monitoring points are arranged around the grouting area and between the core reinforcement zones, with a focus on monitoring areas adjacent to buildings and pipelines.

[0069] Before grouting, ground-penetrating radar is used to scan along the grid lines of the grouting holes in parallel / perpendicular directions to establish the original geological profile; during grouting, real-time scanning is performed, and after every 3 to 5 holes are grouted, the same path is re-measured to compare and analyze the diffusion effect.

[0070] The pressure sensor is preferably diffused silicon type, with a range of 0-10MPa, an accuracy of ±0.5%FS, a sampling rate of 200Hz, and is resistant to slurry corrosion and vibration.

[0071] The preferred flow sensor is an electromagnetic flow meter with a range of 0-50L / min and an accuracy of ±1% of the reading, suitable for media such as cement slurry and dual-liquid slurry.

[0072] The preferred ground deformation sensor is a fiber optic grating demodulator with a resolution of 0.1 mm, a measurement point spacing of 10 cm, a demodulator type of FBG-IM-04, and 16 channels, which can capture ground subsidence or uplift in real time.

[0073] The preferred ground-penetrating radar is a 100MHz ground-penetrating radar with a scanning speed of 30 lines / second, a resolution of 10cm×10cm, and a depth of 10m, used to monitor the slurry diffusion pattern and changes in soil density.

[0074] Isolation valves can be added between each sensor and the pipeline to prevent slurry from directly contacting the sensor probe, facilitating maintenance and calibration. The sensor cables are double-shielded and laid in conduits. The ground-penetrating radar antenna is equipped with a vibration-damping bracket, and the fiber optic demodulator is equipped with a dust cover to reduce data acquisition errors in vibration and dusty environments.

[0075] S304. To facilitate rapid and efficient data analysis and ensure the accuracy of subsequent dynamic adjustment of grouting parameters, a real-time data transmission and processing system can be built.

[0076] 1. Transmission Network Construction

[0077] Pressure and flow sensors are connected to the field controller via RS485 wired connection to avoid interference from grouting vibration.

[0078] The ground deformation sensor and ground-penetrating radar use LoRa wireless transmission modules, which are resistant to electromagnetic interference and transmit data with encryption.

[0079] A data acquisition gateway is set up on-site to convert the signals from various distributed sensors into TCP / IP protocol and upload them to the cloud or local server.

[0080] 2. Core Data Processing Module

[0081] The collected data is filtered to remove outliers caused by grouting vibration, and the data from each sensor is unified according to timestamps. A time-series database is established to store data for the entire grouting process (sensor ID, time, value, operating condition), supporting historical traceability and trend analysis. Thresholds for pressure and flow rate mutations are set, and abnormal data is marked as "pending review" to avoid invalid data interfering with decision-making.

[0082] S305, Segmented Grouting Construction

[0083] Segmented grouting is the core step in sleeve valve pipe construction, requiring strict control of grouting pressure, flow rate, and sequence to ensure uniform grout diffusion. Initialized grouting parameters and graded early warning thresholds are designed based on actual site requirements and engineering experience. An early warning is triggered if the pressure deviates from the preset value by ±10%, the flow rate by ±20%, the cumulative ground deformation ≥3mm or the rate ≥1.5mm per hour, or the diffusion radius deviates from the preset value by ±15%.

[0084] Grouting is performed using a bottom-up, segmented lifting method: First, the grouting core tube with sealing airbag is lowered into the target grouting section at the bottom of the sleeve valve tube. The airbag is then inflated (pressure 0.2~0.3MPa) to seal the upper and lower ends of the section, forming a closed grouting space.

[0085] Reference Figure 7 Start the grouting pump and inject grout into the section according to the design pressure and flow rate, and monitor the pressure, flow rate, grout diffusion radius and ground deformation data in real time.

[0086] Before formal grouting, select 1-2 grouting holes and start construction according to the initialization parameters. All sensors are activated synchronously throughout the process for data acquisition. During grouting, pressure sensors capture real-time pressure changes at the grouting port and pump outlet, flow sensors record instantaneous flow rate and cumulative grouting volume, ground deformation sensors collect surface settlement or uplift data every 10 seconds, and ground-penetrating radar performs re-measurement along a preset scan line after single-hole grouting is completed to obtain underground profile images of grout diffusion.

[0087] Real-time monitoring of multi-source data dynamics was implemented: pressure and flow data were processed using moving average filtering to remove peak anomalies caused by vibration interference; ground deformation data were processed using Kalman filtering to eliminate environmental interference; and ground-penetrating radar data, after background removal and gain adjustment, extracted the boundary of the high-resistivity zone formed by slurry filling. The correlation between "pressure-flow-ground deformation-diffusion radius" was analyzed to verify the suitability of the initialization parameters.

[0088] Based on the grouting test data, core parameters are corrected: if frequent pressure fluctuations are found, and the flow rate fluctuates synchronously but the ground deformation is normal, it is determined to be caused by uneven formation. The correction rule is to adopt a "step-up pressure" mode (increasing by 0.1 MPa every 5 minutes); if the radar shows that the diffusion radius is lower than the design value, but the pressure and flow rate are normal, the pressure is appropriately increased, and the warning threshold is calibrated to ensure safety redundancy. After the trial grouting is completed, optimized parameter benchmarks and warning thresholds are formed to provide accurate guidance for formal grouting.

[0089] For the subsurface soil layers consisting of fill, fine sand, silty clay, silty clay, and coarse sand, the design parameters for sleeve valve grouting construction are as follows:

[0090] Water-cement ratio: 0.8~1.0

[0091] Cement type and strength: PO42.5

[0092] The shell material has a 24-hour strength of 0.35~0.5MPa. After drilling, the mud inside the hole should be replaced.

[0093] The borehole should be sealed with sealing cement grout within 1.0m below the borehole opening;

[0094] Open-loop pressure: 0.8 MPa, injection stop pressure ≤ 1.0 MPa;

[0095] Step-by-step grouting spacing: 2.0m;

[0096] The grouting time for each step is 10-20 minutes;

[0097] Cement absorption capacity (cement): 175~225 kg / m for silty clay layer; 100~150 kg / m for sand layer; 150~200 kg / m for fill layer;

[0098] Average grouting volume per hole: 2 tons of cement / hole;

[0099] Average grouting time per hole: 2 hours, maximum 4.5 hours, minimum 1.5 hours.

[0100] S4. Dynamically adjust the grouting parameters of the sleeve valve pipe according to the grouting pressure, flow rate, grout diffusion radius, and surface deformation during the grouting process.

[0101] S401, Threshold Setting and Early Warning

[0102] Based on the design documents and geological conditions, preset safety thresholds are set for each parameter. If the safety threshold is exceeded, the system will trigger an alarm, push a warning message, and prompt the user to check the grouting parameters.

[0103] S402, Automatic Adjustment Process

[0104] Real-time monitoring of pressure, flow rate, floor deformation, and slurry diffusion radius; establishment of trend curves comparing these parameters with preset parameter benchmarks over time; adjustment of corresponding parameters based on the cause of any abnormal data characteristics if abnormal data characteristics are observed.

[0105] Increased pressure, decreased flow rate, and no significant change in surface deformation (pressure increase ≥15%, flow rate decrease ≥30%) indicate pipeline blockage or dense formation. Grouting should be suspended, and after backflushing, the grouting pressure should be reduced while maintaining the flow rate. If there is no improvement after backflushing, the grout mix ratio should be adjusted.

[0106] A decrease in pressure and an increase in flow rate (pressure decrease ≥20%, flow rate increase ≥20%) indicate large formation porosity or grout leakage. Adjusting the water-cement ratio to increase the grout concentration will reduce the flow rate. Intermittent grouting can be adopted, for example, grouting for 30 seconds followed by a 10-second pause.

[0107] Periodic pressure fluctuations (±10%) indicate formation heterogeneity or changes in the grouting section interface. A stepped pressurization mode is adopted, for example, increasing the pressure by 0.1 MPa every 5 minutes, while keeping the flow rate stable within ±5% of the design value.

[0108] If the ground heave exceeds the standard (ground deformation ≥4mm), reduce the grouting pressure and extend the grouting time for that section to avoid concentrated grouting causing excessive ground deformation, or suspend grouting and resume work after the pressure dissipates by reducing the grouting pressure.

[0109] The ground-penetrating radar showed that the grout diffusion radius was insufficient (grout diffusion radius ≤ 85% of the design value), so the grouting volume was increased and the grouting time for this section was extended;

[0110] When ground-penetrating radar shows that the slurry diffusion radius exceeds the standard (overlap rate of adjacent boreholes R < 15%) and the surface deformation of the adjacent area increases, the flow rate is reduced and intermittent grouting is adopted to control the diffusion boundary.

[0111] This control method can shorten the response time for adjusting grouting parameters, reduce the rate of excessive deformation of the ground, improve the effective utilization rate of grout, reduce ineffective diffusion and waste, and improve the rate of single-hole reinforcement effect compliance.

[0112] S5. Grouting completion determination

[0113] The system will indicate the end of single-hole grouting when the following conditions are met: when the pressure rises to the preset value and stabilizes for 5-10 minutes, and the grouting volume reaches 1-1.2 times the theoretical amount required for this section, stop grouting for this section, release the air and recover the airbag, lift the core tube to the next section, and repeat the above operation.

[0114] The grouting sequence should follow the principle of skipping holes and grouting from the periphery to the interior to avoid cross-grouting between adjacent holes; in the same area, the peripheral holes should be constructed first to form a closed loop, and then the internal holes should be constructed to enhance the grout constraint.

[0115] After single-hole grouting is completed, the hole must be sealed according to specifications to prevent grout backflow or hole collapse. When the last section of grouting reaches the completion standard (stable pressure and grout volume meets the standard), stop grouting and turn off the grouting pump. First, release the pressure of the core tube air bladder, slowly pull out the core tube, and then inject cement grout into the sleeve valve tube until it overflows from the hole. Then, seal the hole with a wooden plug or cement mortar to ensure that the hole is full of grout.

[0116] S6. After all grouting holes have been grouted, the following shape is formed: Figure 1 The composite foundation is shown. The specific penetration resistance values ​​of each soil layer are obtained. Based on the correspondence between deformation parameters and specific penetration resistance, the deformation parameters of the foundation after grouting reinforcement are obtained. The specific penetration resistance values ​​and deformation parameters are used to determine whether the reinforcement construction meets the standards.

[0117] In the detailed implementation, the same hole layout principle as in S201 is adopted. Static cone penetration tests are conducted on the grout-reinforced foundation 14 and 28 days after grouting. The testing method is the same as before grouting to ensure data comparability. The specific penetration resistance value Ps' of each soil layer after grouting is recorded. According to the original soil layer division, the average value of Ps' after grouting (Ps'_avg) of each layer is extracted. Ps'_avg is substituted into the deformation parameter E0 / Es and specific penetration resistance Ps formula established in step S203 to calculate the compression modulus Es' and deformation modulus E0' of each layer after grouting.

[0118] Calculate the increase rate of specific penetration resistance before and after grouting ΔPs = (Ps'_avg - Ps_avg) / Ps_avg × 100%, and the ratio of deformation parameters after grouting to deformation parameters before grouting E0' / E0 and Es' / Es. Based on the results, determine whether the reinforcement construction meets the standards.

[0119] The criteria for judging whether reinforcement construction meets the standards include: ΔPs≥40%, E0' / E0≥1.5, Es' / Es≥1.5.

[0120] If the standard is not met, a grouting plan needs to be developed for further reinforcement.

[0121] It can also calculate and predict post-construction settlement, providing clear time nodes for later operation and maintenance, and formulating regular monitoring plans in advance to avoid fatigue of rack structure and expansion of floor damage due to settlement accumulation, thereby reducing the blindness and cost of later operation and maintenance.

[0122] The above examples are merely illustrative of the present invention and do not constitute a limitation on the scope of protection of the present invention. All designs that are the same as or similar to the present invention are within the scope of protection of the present invention.

Claims

1. A method for reinforcing the floor of an existing building, characterized in that, Includes the following steps: Design grouting holes; Establish the relationship between the deformation parameters of the foundation soil layer before grouting and the specific penetration resistance; Grouting is performed in sections into the grouting hole using a sleeve valve pipe; Based on the grouting pressure, flow rate, grout diffusion radius, and surface deformation during the grouting process, the grouting parameters of the sleeve valve pipe are dynamically adjusted until the grouting of a single hole is completed. After all grouting holes have been filled, the specific penetration resistance value of each soil layer is obtained. Based on the correspondence between deformation parameters and specific penetration resistance, the deformation parameters of the foundation after grouting reinforcement are obtained. The specific penetration resistance value and deformation parameters are used to determine whether the reinforcement construction meets the standards.

2. The method for reinforcing the ground of existing buildings as described in claim 1, characterized in that: The grouting holes include vertical grouting holes and inclined grouting holes; the inclined grouting holes are arranged intersectingly between the laterally adjacent vertical grouting holes to form a three-dimensional grouting network.

3. The method for reinforcing the ground of existing buildings as described in claim 1, characterized in that: The inclination angle of the inclined grouting hole is 20°.

4. The method for reinforcing the floor of existing buildings as described in claim 1, characterized in that, The establishment of the correspondence between the deformation parameters of the foundation soil layer before grouting and the specific penetration resistance includes: recording the specific penetration resistance Ps through static penetration tests; obtaining the deformation parameters of the foundation soil layer through supplementary drilling, including the compression modulus Es and the deformation modulus E0; and establishing the formula between the deformation parameter E0 / Es and the specific penetration resistance Ps.

5. The method for reinforcing the floor of existing buildings as described in claim 1, characterized in that, The segmented grouting into the grouting hole using sleeve valve pipes includes: adjusting the verticality of the drilling rig and drilling a hole with a diameter larger than the outer diameter of the sleeve valve pipe; cutting sleeve valve pipes of corresponding lengths according to the hole depth and connecting them section by section; placing the sleeve valve pipe into the center of the drill hole; filling the annular space between the sleeve valve pipe and the hole wall with casing material and curing it; connecting the outlet of the grouting pump to the top interface of the sleeve valve pipe; preparing the grout according to the design ratio and grouting in a bottom-up, segmented lifting manner.

6. The method for reinforcing the ground of existing buildings as described in claim 1, characterized in that, The dynamically adjustable sleeve valve grouting parameters include: real-time monitoring of pressure, flow rate, ground deformation, and grout diffusion radius during the grouting process, establishing trend curves of these parameters and preset parameters over time, and adjusting the corresponding parameters according to the cause of any abnormal data characteristics.

7. The method for reinforcing the ground of existing buildings as described in claim 6, characterized in that, The adjustment of corresponding parameters based on the cause of deviation specifically includes: When the pressure increases, the flow rate decreases, and the surface deformation does not change significantly, grouting is suspended, and after reverse flushing, the grouting pressure is reduced while the flow rate remains unchanged. When the pressure drops and the flow rate increases, increase the grout concentration, reduce the flow rate, and use intermittent grouting. If the ground heave exceeds the standard, grouting should be suspended and the grouting pressure reduced after the pressure dissipates. If the grout diffusion radius is insufficient, increase the grouting volume and extend the grouting time for that section. When the grout diffusion radius exceeds the standard and the surface deformation in the adjacent area increases, the flow rate should be reduced and intermittent grouting should be adopted to control the diffusion boundary.

8. The method for reinforcing the ground of existing buildings as described in claim 1, characterized in that: The grouting of a single hole is terminated when the grouting volume reaches 1 to 1.2 times the preset value and the pressure remains stable at the preset value for 5 to 10 minutes.

9. The method for reinforcing the floor of existing buildings as described in claim 1, characterized in that, The steps for obtaining the deformation parameters of the foundation after grouting reinforcement include: conducting static cone penetration tests on the foundation 14 days and 28 days after grouting, obtaining the specific penetration resistance Ps value of each soil layer, and comparing the established relationship between deformation parameters and specific penetration resistance to obtain the deformation parameters of the foundation after grouting reinforcement.

10. The method for reinforcing the floor of an existing building as described in claim 1, characterized in that, The criteria for judging whether the reinforcement construction meets the standards include: the increase rate of penetration resistance before and after grouting is ≥40%; and the ratio of deformation parameters after grouting to deformation parameters before grouting is ≥1.5.

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