Construction method for ground reinforcement of historical building by lime-sand pile based on reaction force calculation model

Abstract

The present invention discloses a construction method for strengthening the foundation of a historical building with lime-sand piles based on a reaction force calculation model, belonging to the technical field of foundation treatment and foundation engineering, including S1. Conduct a current situation assessment of the historical building and make construction preparations; S2. According to the data obtained in S1, establish an elastic foundation beam model and calculate the reaction force threshold required for the reinforcement area; S3. Determine the mix ratio of lime-sand piles, pile length, pile diameter, and pile spacing required for the bearing capacity; S4. Carry out the construction work for strengthening the lime-sand pile foundation; S5. Conduct inspections during the construction process and after completion; S6. Real-time monitor the data of foundation settlement and stress changes, and optimize the construction plan and post-maintenance strategy; The construction method for strengthening the foundation of a historical building with lime-sand piles based on a reaction force calculation model provided by the present invention can effectively improve the foundation bearing capacity and stability of the historical building without damaging the original style and features of the historical building through accurate calculations and reasonable construction plans, ensuring the safety and durability of the building.

Description

Technical Field

[0001] The present invention relates to the technical field of foundation treatment and foundation engineering, and particularly relates to a construction method for strengthening the foundation of historical buildings with lime-sand piles based on a reaction force calculation model. Background Technique

[0002] Historical buildings usually have important cultural and historical values. However, over time, their foundations may experience problems such as aging and settlement, which affect the safety and stability of the buildings. Therefore, strengthening the foundation of historical buildings is a key link in protection and restoration work. However, due to the uniqueness and sensitivity of historical buildings, traditional strengthening methods may not be applicable, and more refined and technically advanced strengthening schemes are required.

[0003] Therefore, this paper designs a construction method for strengthening the foundation of historical buildings with lime-sand piles based on a reaction force calculation model. Lime-sand piles are a common foundation strengthening method, especially suitable for the treatment of soft soil foundations. It forms a composite foundation by driving piles made of a mixture of cement (or lime) and sand into the soft soil layer, thereby improving the overall performance of the foundation. For historical buildings, the lime-sand pile strengthening technology has the advantages of low vibration, high adaptability, and economy. Evaluating and designing the foundation strengthening scheme through the reaction force calculation model helps engineers accurately predict the bearing capacity and deformation characteristics of the foundation after strengthening, ensuring the effectiveness and safety of the strengthening scheme. Summary of the Invention

[0004] The purpose of the present invention is to provide a construction method for strengthening the foundation of historical buildings with lime-sand piles based on a reaction force calculation model to solve the problems existing in the above background technique.

[0005] To achieve the above purpose, the present invention provides a construction method for strengthening the foundation of historical buildings with lime-sand piles based on a reaction force calculation model, including the following steps:

[0006] S1. Conduct a current situation assessment of the historical building and make construction preparations;

[0007] S2. According to the data obtained in step S1, establish an elastic foundation beam model and calculate the reaction force threshold required for the strengthening area;

[0008] S3. According to the bearing capacity required by the historical building, use a lime-sand pile reaction force tester to determine the mix ratio, pile length, pile diameter, and pile spacing of the lime-sand piles required for the bearing capacity;

[0009] S4. Carry out the construction work of strengthening the lime-sand pile foundation;

[0010] S5. Conduct quality control inspections during the construction process and inspections after completion;

[0011] S6. Integrate Internet of Things sensors to monitor the data of foundation settlement and stress changes in real time, and optimize the construction plan and post-maintenance strategy through big data analysis.

[0012] Preferably, the current situation assessment in step S1 includes structural assessment, geological exploration and risk assessment. The structural assessment includes evaluating the materials, structural forms and bearing capacities of historical buildings, etc.; the geological exploration is used to obtain information such as foundation soil parameters, soil layer distribution, groundwater level and bearing capacity, etc.; the risk assessment is used to evaluate the risks occurring during the construction process, such as settlement, inclination, cracking, etc., and formulate corresponding emergency plans; the bearing capacity information is obtained through collapsibility tests and soil layer shear tests on the obtained soil samples.

[0013] Preferably, step S2 specifically includes:

[0014] S21. Obtain the soil layer distribution and physical and mechanical properties of the foundation according to the geological exploration in step S1, and clarify the basic parameters for subsequent calculations;

[0015] S22. Calculate the load transferred from the upper structure of the historical building to the foundation;

[0016] S23. Calculate the foundation bearing capacity of the historical building and the requirements considering the deformation characteristics;

[0017] S24. Calculate the reaction force threshold required for the foundation reinforcement area according to the balance relationship between the upper structure load received by the foundation and the reaction force of the foundation soil.

[0018] Preferably, the calculation of the foundation bearing capacity in step S23 is specifically as follows: Determine the foundation bearing capacity through a plate load test. According to the principle of an elastic semi-infinite surface under load, the calculation formula for the soil deformation modulus is:

[0019] ;

[0020] Among them, is a coefficient, is the Poisson's ratio of the foundation soil, is the pressure at the bottom surface of the bearing plate, is the settlement corresponding to the load ; is the diameter of the circular bearing plate or the side length of the square bearing plate; Calculate the ultimate bearing capacity of the foundation according to the soil deformation modulus, and the formula is:

[0021] ;

[0022] Among them, is the shear strength, , , are coefficients calculated according to their characteristic parameters, is the effective stress, is the unit weight of the base bottom, is the foundation area; in actual use, a safety factor is introduced to calculate the allowable bearing capacity adopted in actual design, and the calculation formula is:

[0023] ;

[0024] wherein, is the safety factor.

[0025] Preferably, the specific implementation steps for analyzing the foundation deformation characteristics in step S23 are as follows:

[0026] ①. Determine the foundation parameters, load conditions, and foundation parameters, specifically obtained through on-site tests or laboratory tests;

[0027] ②. Establish the Boussinesd elastic theory model and its corresponding mathematical equations;

[0028] ③. Calculate the settlement amount according to the mathematical equations in step ②, including single-point settlement and multi-point settlement. For single-point settlement, calculate the settlement amount of each specific point; for multi-point settlement, repeat the calculation for multiple points within the entire foundation range to obtain a complete settlement distribution map;

[0029] ④. Plot the settlement values of each calculated point into a graph to form a settlement curve for visually understanding the distribution law of settlement;

[0030] ⑤. Evaluate the overall stability and potential risks of the building by comparing the settlement amounts at different positions; at the same time, calculate the inclination according to the settlement difference at the four corner points of the building to determine whether it exceeds the specification allowable value;

[0031] ⑥. Consider the secondary consolidation effect and creep phenomenon, and use empirical formulas or numerical simulation methods for long-term prediction.

[0032] Preferably, the mathematical equations in step ② include stress components and displacement components, and the stress component expressions are:

[0033] Vertical normal stress: , the negative sign indicates compressive stress;

[0034] Radial normal stress: ;

[0035] Shearing force: ;

[0036] wherein, is the load, specifically the concentrated force applied vertically downward at a certain point on the ground surface; is the rectangular coordinate system established with the load as the origin; is the distance from the load point to the calculation point;

[0037] The displacement component expressions are as follows:

[0038] Vertical displacement: ;

[0039] Radial displacement: .

[0040] Preferably, the reaction force threshold in step S24 is calculated as:

[0041] ;

[0042] Wherein, is the foundation reaction force, is the design value of the vertical force transmitted from the superstructure to the top surface of the foundation, is the self-weight of the foundation and the weight of the soil on the foundation, is the bottom area of the foundation; and it satisfies .

[0043] Preferably, step S3 specifically includes:

[0044] S31. According to the structural characteristics of the historical building and the reaction force threshold calculated in step S2, clarify the target bearing capacity to be achieved after the lime-sand pile foundation reinforcement. The formula is:

[0045] ;

[0046] S32. Through the lime-sand pile reaction force tester, conduct on-site tests on lime-sand piles with different ratios, pile lengths, pile diameters and pile spacings, monitor the reaction force changes of the lime-sand piles in real time, and record the test data under different working conditions;

[0047] S33. Analyze the test data, analyze the relationship between the ratio, pile length, pile diameter and pile spacing of the lime-sand piles and the bearing capacity, and determine the ratio, pile length, pile diameter and pile spacing of the lime-sand piles required for the foundation reinforcement of the historical building.

[0048] Preferably, step S4 specifically includes:

[0049] S41. According to the reinforcement plan, accurately mark the position of each pile on the ground, and use a drill to drill holes according to the design depth to ensure that the hole diameter and verticality meet the requirements;

[0050] S42. After the drilling is completed, conduct hole cleaning treatment to remove the mud and debris in the hole and ensure that the bottom of the hole is clean;

[0051] S43. Mix the lime-sand according to the ratio determined in step S33, stir evenly to ensure the uniformity and fluidity of the mixture, inject the mixed lime-sand into the hole through the pouring equipment, and vibrate while pouring to ensure that the lime-sand densely fills the hole;

[0052] After perfusion is completed, the pile top is processed to ensure it is flat and dense, preventing water loss.

[0053] Preferably, step S5 specifically includes:

[0054] S51. During the construction process, the deformation of the foundation is monitored in real time to ensure the smooth and controllable construction process. According to the monitoring results, the construction parameters, including the lime-sand ratio and perfusion speed, are adjusted in a timely manner to ensure the construction quality.

[0055] S52. A static load test is carried out on the completed lime-sand piles to check whether their bearing capacity meets the design requirements; non-destructive testing techniques (such as ultrasonic waves, radar, etc.) are used to check the internal quality of the lime-sand piles to ensure their integrity; and within a certain period after construction, settlement observations are regularly carried out to record the settlement of the building to ensure the reinforcement effect.

[0056] Therefore, the present invention adopts the above-mentioned construction method for strengthening the lime-sand pile foundation of historical buildings based on the reaction force calculation model, and has the following beneficial effects:

[0057] (1) Through the reaction force calculation model, accurately obtaining basic data, establishing a mathematical model, solving the bearing capacity of the foundation, calculating the deformation characteristics, and with the aid of numerical simulation means, the performance of the foundation can be effectively predicted and controlled.

[0058] (2) Through the elastic theory model, accurately obtaining the foundation and foundation parameters, establishing a mathematical model, solving the settlement amount, drawing the settlement curve, analyzing the differential settlement, conducting long-term settlement prediction, and with the aid of numerical simulation means, the performance of the foundation after reinforcement can be effectively predicted and controlled.

[0059] Next, through the drawings and embodiments, the technical solutions of the present invention will be further described in detail. Brief Description of the Drawings

[0060] Figure 1 It is a flow chart of the construction method for strengthening the lime-sand pile foundation of historical buildings based on the reaction force calculation model of the present invention;

[0061] Figure 2 It is a schematic diagram for calculating the reaction force threshold required for the reinforcement area in the embodiment of the present invention;

[0062] Figure 3 It is a schematic diagram of the reaction force calculation model in the embodiment of the present invention. Detailed Embodiments

[0063] The following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0064] Please refer to Figures 1 - 3 , a construction method for strengthening the foundation of a historical building's lime-sand pile based on a reaction force calculation model, including the following steps:

[0065] S1. Conduct a current situation assessment of the historical building and make construction preparations; the current situation assessment includes structural assessment, geological exploration, and risk assessment. The structural assessment includes evaluating the materials, structural form, bearing capacity, etc. of the historical building; geological exploration is used to obtain information such as foundation soil parameters, soil layer distribution, groundwater level, and bearing capacity; risk assessment is used to evaluate risks that occur during construction, such as settlement, inclination, cracking, etc., and formulate corresponding emergency plans; the bearing capacity information is obtained through collapsibility tests and soil layer shear tests on the obtained soil samples.

[0066] S2. Based on the data obtained in step S1, establish an elastic foundation beam model and calculate the reaction force threshold required for the reinforcement area; specifically including:

[0067] S21. According to the soil layer distribution and physical and mechanical properties of the foundation obtained in step S1, clarify the foundation parameters for subsequent calculations;

[0068] S22. Calculate the load transmitted from the upper structure of the historical building to the foundation;

[0069] S23. Calculate the foundation bearing capacity of the historical building and the requirements considering the deformation characteristics; the calculation of the foundation bearing capacity is specifically: determine the foundation bearing capacity through a plate load test, and according to the principle of an elastic semi-infinite surface under load, obtain the calculation formula for the soil deformation modulus: as follows:

[0070] ;

[0071] Among them, is a coefficient, is the Poisson's ratio of the foundation soil, is the pressure at the bottom surface of the bearing plate, is the settlement corresponding to the load , is the diameter of the circular bearing plate or the side length of the square bearing plate; calculate the ultimate bearing capacity of the foundation according to the soil deformation modulus, and the formula is:

[0072] ;

[0073] Among them, is the shear strength, , , are coefficients calculated according to their characteristic parameters, is the effective stress, is the unit weight of the base bottom, is the foundation area; in actual use, a safety factor is introduced to calculate the allowable bearing capacity used in actual design. The calculation formula is:

[0074] ;

[0075] wherein, is the safety factor.

[0076] The specific implementation steps for analyzing the foundation deformation characteristics are as follows:

[0077] ①. Determine the foundation parameters, load conditions, and foundation parameters, specifically obtained through on-site tests or laboratory tests;

[0078] ②. Establish the Boussinesq elastic theory model and its corresponding mathematical equations. The mathematical equations include stress components and displacement components. The stress component expressions are:

[0079] Vertical normal stress: , and the negative sign indicates compressive stress;

[0080] Radial normal stress: ;

[0081] Shearing force: ;

[0082] wherein, is the load, specifically the concentrated force applied vertically downward at a certain point on the ground surface; is the rectangular coordinate system established with the load as the origin; is the distance from the load point to the calculation point;

[0083] The displacement component expressions are:

[0084] Vertical displacement: ;

[0085] Radial displacement: ;

[0086] ③. Calculate the settlement amount according to the mathematical equations in step S2, including single-point settlement and multi-point settlement. For single-point settlement, calculate the settlement amount of each specific point; for multi-point settlement, repeat the calculation for multiple points within the entire foundation range to obtain a complete settlement distribution map;

[0087] ④. Plot the settlement values of each calculated point into a graph to form a settlement curve for visually understanding the distribution law of settlement;

[0088] ⑤. Evaluate the overall stability and potential risks of the building by comparing the settlement amounts at different positions; meanwhile, calculate the inclination based on the settlement difference of the four corner points of the building and determine whether it exceeds the allowable value specified in the code;

[0089] ⑥. Consider the secondary consolidation effect and creep phenomenon, and adopt empirical formulas or numerical simulation methods for long-term prediction.

[0090] S24. Calculate the reaction force threshold required for the foundation reinforcement area according to the balance relationship between the superstructure load borne by the foundation and the reaction force of the foundation soil. The calculation formula is:

[0091] ;

[0092] where, is the foundation reaction force, is the design value of the vertical force transmitted from the superstructure to the top surface of the foundation, is the self-weight of the foundation and the weight of the soil on the foundation, is the bottom area of the foundation; and it satisfies .

[0093] S3. According to the bearing capacity required for the historical building, use a lime-sand pile reaction force tester to determine the mix ratio of lime-sand piles, pile length, pile diameter, and pile spacing required for the bearing capacity; specifically including:

[0094] S31. According to the structural characteristics of the historical building and the reaction force threshold calculated in step S2, clarify the target bearing capacity to be achieved after the lime-sand pile foundation reinforcement. The formula is:

[0095] ;

[0096] S32. Through the lime-sand pile reaction force tester, conduct on-site tests on lime-sand piles with different mix ratios, pile lengths, pile diameters, and pile spacings, monitor the reaction force changes of lime-sand piles in real time, and record the test data under different working conditions;

[0097] S33. Analyze the test data, analyze the relationship between the mix ratio, pile length, pile diameter, and pile spacing of lime-sand piles and the bearing capacity, and determine the mix ratio, pile length, pile diameter, and pile spacing of lime-sand piles required for the foundation reinforcement of the historical building.

[0098] S4. Carry out the construction work of lime-sand pile foundation reinforcement; specifically including:

[0099] S41. According to the reinforcement plan, accurately mark the position of each pile on the ground, and use a drill to drill holes according to the design depth to ensure that the hole diameter and verticality meet the requirements;

[0100] S42. After the drilling is completed, carry out hole cleaning to remove the mud and debris in the hole and ensure that the bottom of the hole is clean.

[0101] S43. Mix the lime sand according to the ratio determined in step S33, stir evenly to ensure the uniformity and fluidity of the mixture, inject the mixed lime sand into the hole through the pouring equipment, and vibrate while pouring to ensure that the lime sand densely fills the hole.

[0102] S44. After the pouring is completed, treat the top of the pile to ensure that the top of the pile is flat and dense and prevent water loss.

[0103] S5. Conduct quality control inspections during the construction process and inspections after completion; specifically including:

[0104] S51. During the construction process, monitor the deformation of the foundation in real time to ensure that the construction process is stable and controllable. According to the monitoring results, adjust the construction parameters in a timely manner, including the lime sand ratio and pouring speed, etc., to ensure the construction quality.

[0105] S52. Conduct static load tests on the completed lime sand piles to check whether their bearing capacity meets the design requirements; use non-destructive testing techniques (such as ultrasonic waves, radar, etc.) to check the internal quality of the lime sand piles to ensure their integrity; and conduct regular settlement observations within a certain period after construction to record the settlement of the building and ensure the reinforcement effect.

[0106] S6. Regularly inspect the reinforced foundation and building to check for any abnormal conditions. When abnormal conditions are found, take measures in a timely manner for repair and maintenance to ensure the safety and stability of the building. Integrate Internet of Things sensors to monitor the foundation settlement and stress change data in real time, optimize the construction plan and post-maintenance strategy through big data analysis, so as to conduct long-term monitoring of the building. The accumulated data can be used for subsequent analysis. By regularly analyzing the monitoring data, the reinforcement effect can be evaluated, providing a basis for future maintenance and management.

[0107] A historical building in a certain city was built in the late Qing Dynasty and the early Republic of China. The courtyard faces north with a south orientation, 33 meters long from east to west, 32 meters wide from north to south, covering an area of about 1,050 square meters and a building area of 485 square meters. It adopts a construction method combining Chinese and Western styles, with a Western-style plane layout and indoor and outdoor decorations, and a Chinese-style roof with tile roofs. For the reinforcement and repair of the main building structure, after three months of construction, the construction of all lime sand piles was completed. The effectiveness of this embodiment can be proved by the following reinforcement results:

[0108] I. In terms of settlement control

[0109] Before construction, the predicted single-point settlement amounts at the four corner points of the building were: 15 mm at corner point A, 18 mm at corner point B, 16 mm at corner point C, and 14 mm at corner point D. There was a certain degree of uneven settlement overall, with the calculated inclination approaching 0.3%, close to the dangerous edge, indicating that the foundation stability was a concern. After the reinforcement construction was completed, after a period of settlement observation, the settlements at the four corner points tended to be stable, and the final settlement amounts were: 3 mm at corner point A, 4 mm at corner point B, 3.5 mm at corner point C, and 2.5 mm at corner point D. The inclination was reduced to less than 0.1%, meeting the extremely high requirements for stability of the ancient building. There was no obvious inclination appearance on the building exterior, and the due solemnity and beauty were restored.

[0110] II. In terms of bearing capacity improvement

[0111] Before construction, by means of plate load tests and other methods, the characteristic value of the bearing capacity of the original foundation soil was determined to be 120 kPa. Considering the weight of the upper structure of the building and subsequent possible usage scenarios, according to the reaction force calculation model, it was calculated that the foundation bearing capacity needed to be increased to at least 200 kPa to ensure the safety and stability of the building.

[0112] After being reinforced with lime-sand piles, the static load test showed that the foundation bearing capacity reached above 220 kPa, meeting and exceeding the expected target, ensuring that the bearing capacity of the building structure was effectively enhanced, and no cracking, deformation and other problems caused by insufficient bearing capacity occurred in the subsequent building structure.

[0113] III. In terms of quality inspection of lime-sand piles

[0114] During the construction process, non-destructive testing (such as ultrasonic testing) of lime-sand piles showed that the integrity of the pile body was good, and no common quality defects such as broken piles and necking occurred. The compactness of the pile body concrete reached more than 95% of the design requirements, ensuring that each lime-sand pile could effectively play the role of bearing and transferring loads.

[0115] After sampling and inspecting lime-sand piles with different combinations of ratios, pile lengths, pile diameters and pile spacings, the optimal mix ratio was determined as cement: sand: lime = 3:2:5 (mass ratio), the pile length was 8 m, the pile diameter was 0.5 m, and the pile spacing was 1.2 m. The lime-sand piles constructed according to these parameters performed stably in the reaction force test, and the average single-pile reaction force reached above 300 kN, providing a solid support for the overall foundation reinforcement effect.

[0116] At the same time, the inspection personnel were arranged to conduct regular observations. It was found through the observations that there was a rising trend at corner points B and C of the building within 2 weeks after implementation, which were 1 mm and 2 mm respectively, and then stopped developing and remained unchanged. Corner point A had tended to be stable and no longer settled. Subsequently, the settlement was observed successively within 1 - 2 years after completion. The foundation within the reinforcement area was basically all stable, proving that the foundation could be effectively reinforced by implementing this method.

[0117] Therefore, the present invention adopts the above construction method for reinforcing the foundation of the historical building with lime-sand piles based on the reaction force calculation model, which not only helps to protect and repair historical buildings, but also improves the safety and stability of their structures.

[0118] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. Construction method for reinforcing foundation of historical building with lime-sand pile based on reaction force calculation model, characterized in that It includes the following steps: S1. Conduct a current situation assessment of the historical building and make construction preparations; S2. According to the data obtained in step S1, establish an elastic foundation beam model and calculate the reaction force threshold required for the reinforcement area; S3. According to the bearing capacity required by the historical building, use a lime-sand pile reaction force tester to determine the mix ratio of lime-sand piles, pile length, pile diameter, and pile spacing required for the bearing capacity; S4. Carry out the construction work of lime-sand pile foundation reinforcement; S5. Conduct quality control inspections during the construction process and inspections after completion; S6. Integrate Internet of Things sensors to monitor the foundation settlement and stress change data in real time, and optimize the construction plan and post-maintenance strategy through big data analysis; The current situation assessment in step S1 includes structural assessment, geological exploration, and risk assessment. The structural assessment includes assessing the materials, structural forms, and bearing capacities of historical buildings; geological exploration is used to obtain foundation soil parameters, soil layer distribution, groundwater level, and bearing capacity information; risk assessment is used to assess the risks that occur during the construction process and formulate corresponding emergency plans; the bearing capacity information is obtained through collapsibility tests and soil layer shear tests on the obtained soil samples; Step S2 specifically includes: S21. According to the soil layer distribution and physical and mechanical properties of the foundation obtained from the geological exploration in step S1, clarify the foundation parameters for subsequent calculations; S22. Calculate the load transmitted from the upper structure of the historical building to the foundation; S23. Calculate the foundation bearing capacity of the historical building and the requirements considering the deformation characteristics; S24. According to the balance relationship between the upper structure load received by the foundation and the reaction force of the foundation soil, calculate the reaction force threshold required for the foundation reinforcement area; The specific implementation steps for the analysis of the foundation deformation characteristics in step S23 are as follows: ①. Determine the foundation parameters, load conditions, and foundation parameters, which are specifically obtained through on-site tests or laboratory tests; ②. Establish the Boussinesd solution elastic theory model and its corresponding mathematical equations; ③. Calculate the settlement amount according to the mathematical equations in step ②, including single-point settlement and multi-point settlement. For single-point settlement, calculate the settlement amount of each specific point; for multi-point settlement, repeat the calculation for multiple points within the entire foundation range to obtain a complete settlement distribution map; ④. Plot the settlement values of each calculated point into a graph to form a settlement curve for visually understanding the distribution law of settlement; ⑤. Evaluate the overall stability and potential risks of the building by comparing the settlement amounts at different positions; at the same time, calculate the inclination according to the settlement difference at the four corners of the building and judge whether it exceeds the allowable value specified in the code; ⑥. Consider the secondary consolidation effect and creep phenomenon, and use empirical formulas or numerical simulation methods for long-term prediction; adjust the reaction force threshold according to the calculated settlement amount under the load to ensure that the foundation deformation does not exceed the allowable value; Step S3 specifically includes: S31. According to the structural characteristics of the historical building and the reaction force threshold calculated in step S2, clarify the target bearing capacity to be achieved after the lime-sand pile foundation reinforcement. The formula is: ； Among them, is the safety factor; is the foundation reaction force; S32. Through a lime-sand pile reaction force tester, conduct on-site tests on lime-sand piles with different mix ratios, pile lengths, pile diameters, and pile spacings, monitor the reaction force changes of lime-sand piles in real time, and record the test data under different working conditions; S33. Analyze the test data to analyze the relationships between the mix ratio, pile length, pile diameter, and pile spacing of the lime-sand piles and the bearing capacity, and determine the mix ratio, pile length, pile diameter, and pile spacing of the lime-sand piles required for the foundation reinforcement of historical buildings.

2. The construction method for reinforcing the foundation of a historical building's lime-sand pile based on the reaction force calculation model according to claim 1, characterized in that, The calculation of the foundation bearing capacity in step S23 is specifically as follows: Determine the foundation bearing capacity through a plate load test. According to the principle of an elastic semi-infinite surface under load, the calculation formula for the soil deformation modulus is obtained as: ； Among them, is a coefficient, is the Poisson's ratio of the foundation soil, is the pressure at the bottom surface of the load-bearing plate, is related to the load corresponding settlement, is the diameter of the circular load-bearing plate or the side length of the square load-bearing plate; the ultimate bearing capacity of the foundation is calculated according to the soil deformation modulus, and the formula is: ； Among them, is the shear strength, , , are coefficients calculated according to their characteristic parameters, is the effective stress, is the unit weight of the bottom of the foundation, is the foundation area; in actual use, a safety factor will be introduced to calculate the allowable bearing capacity adopted in actual design. The calculation formula is: ； Among them, is the safety factor.

3. The construction method for reinforcing the foundation of a historical building with lime-sand piles based on the reaction force calculation model according to claim 1, characterized in that, The reaction threshold of step S24 is calculated as: ； Among them, is the foundation reaction force, is the design value of the vertical force transmitted from the superstructure to the top surface of the foundation, is the self-weight of the foundation and the weight of the soil on the foundation, is the bottom area of the foundation; and it satisfies .

4. The construction method for reinforcing the foundation of a historical building's lime-sand pile based on the reaction force calculation model according to claim 1, characterized in that, Step S4 specifically includes: S41. According to the reinforcement plan, mark the position of each pile on the ground and use a drill to drill holes according to the designed depth. S42. After the drilling is completed, conduct hole cleaning to remove the mud and debris in the hole to ensure the bottom of the hole is clean. S43. Mix the lime and sand according to the mix ratio determined in step S33, stir evenly, and inject the mixed lime and sand into the hole through a perfusion device, and vibrate while perfusion. S44. After the perfusion is completed, treat the pile top.

5. The construction method for reinforcing the foundation of a historical building's lime-sand pile based on the reaction force calculation model according to claim 1, characterized in that, Step S5 specifically includes: S51. During the construction process, monitor the deformation of the foundation in real time. According to the monitoring results, adjust the construction parameters in a timely manner, including the lime-sand mix ratio and perfusion speed. S52. Conduct a static load test on the completed lime-sand piles to check whether their bearing capacity meets the design requirements; use non-destructive testing techniques to check the internal quality of the lime-sand piles; and conduct regular settlement observations within a certain period after construction to record the settlement of the building.

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