A large-scale shaking table foundation vibration control method

Abstract

The present application provides a large-scale vibration table foundation vibration control method, comprising: S101, obtaining large-scale vibration table function requirement and vibration performance parameter data, S102, determining foundation selection and control target value; S103, determining foundation mass index according to the maximum acceleration value of the large-scale vibration table; S104, judging whether the foundation mass in S102 meets the index value in S103, if not, forming an extension part around the foundation in S102; S105, judging whether the overall combined foundation based on S104 meets the target value in S103, if not, filling the counterweight material in the basement interior space of the extension part; S106, performing preliminary analysis of foundation dynamics; if not, adopting pile foundation; and S107, performing foundation dynamics analysis based on the force spectrum of the vibration table actuator, until meeting the requirement of the target value in S102.

Description

Technical Field

[0001] This invention relates to the field of civil engineering, and in particular to a method for controlling the vibration of a large vibration test bench foundation. Background Technology

[0002] Large shaking tables, especially extra-large earthquake simulation shaking test tables, are dynamic equipment with large table dimensions, high test loads, large excitation accelerations, and a wide range of motion displacements and operating frequencies. They can be used for large-scale earthquake simulation tests on large buildings and structures such as civil engineering, bridges, water conservancy, nuclear power, and warehouses. They are of great significance for earthquake science research, disaster risk mitigation capabilities, and achieving major breakthroughs and developments in the engineering field. As a special type of dynamic machine foundation, the dynamic characteristics of shaking table foundations are affected by the mass of the foundation components, the stiffness of the foundation, and damping. Under the reaction force of the shaking table actuator, vibrations will occur, especially for large shaking tables in medium-soft soil sites, where the vibration effect is significant, particularly the low-frequency resonance vibration response. Large shaking tables, under operating conditions, can easily have a significant impact on the health of on-site personnel, the structural safety of the laboratory, and the surrounding environment. Existing national standards and specifications only apply to small and medium-sized shaking tables with actuator output not exceeding 500kN. There is little research and application on the vibration control of large shaking table foundations, especially for ultra-large shaking tables with a table size of 10m x 10m or more and actuator output exceeding 2000kN. There is a severe lack of control indicators for the vibration output of the shaking table foundation and methods for analyzing and controlling the foundation vibration.

[0003] Therefore, new technological approaches are needed to at least partially address the shortcomings of existing technologies. Summary of the Invention

[0004] In order to overcome the shortcomings of existing large shaking table foundation vibration control methods, the inventors of this invention have conducted in-depth research and found that comprehensive measures need to be taken from the following aspects in order to achieve a scientific and reasonable control objective.

[0005] First, it is necessary to formulate scientific and reasonable vibration control target values ​​based on the vibration characteristics of the shaking table foundation.

[0006] Large shaking tables, especially those used for large-scale earthquake simulation vibration tests, are characterized by their large table size, high load-bearing capacity, and wide vibration frequency range, typically from a few tenths of a hertz to tens of hertz. For the same peak vibration acceleration, the vibration response of the foundation varies greatly at different frequencies. For example, for the same vibration displacement, higher frequencies cause greater structural damage and are more noticeably felt by humans. Traditional shaking table foundation vibration control that does not consider frequency characteristics is unscientific. Based on fundamental principles of kinematics, vibrations at different frequencies f and their relationship to the maximum displacement x... m Maximum speed v mMaximum acceleration a m The correspondence,

[0007] a m =2πfv m =4π 2 f 2 x m

[0008] The above formula shows the relationship between maximum displacement, velocity, acceleration, and vibration frequency. Given a fixed vibration frequency, controlling any one of the maximum displacement, velocity, or acceleration determines the other two. For the same vibration acceleration, high-frequency vibration requires stricter displacement control than low-frequency vibration, while the displacement control can be more relaxed for low-frequency vibration. Controlling displacement in low-frequency vibration also controls maximum acceleration, and controlling acceleration in high-frequency vibration inevitably controls maximum displacement. From an engineering perspective, low-frequency vibration limits the maximum displacement x. m Maximum acceleration a is limited at high frequencies. m Mid-frequency controlled vibration maximum velocity v m The target value for basic vibration control is more scientific and reasonable.

[0009] Second, based on the site environment and the vibration output characteristics of the shaking table foundation, more effective and targeted vibration control measures should be determined for the vibration mass of the foundation, the stiffness of the foundation, and the damping of the foundation.

[0010] From the equilibrium equation of simple harmonic dynamics, we can see that:

[0011] [M]{y″}+[C]{y′}+[K]{y}={Fsinθt}

[0012] In this context, {Fsinθt} represents the dynamic parameters required to meet the functional requirements of the shaking table; vibration acceleration {y″}, vibration velocity {y′}, and vibration displacement {y} are the variables in the vibration equilibrium equation; vibration mass [M], damping coefficient [C], and foundation stiffness [K] are the key characteristic parameters for vibration control. Under the same conditions, at high frequencies, the maximum vibration acceleration is higher, making increasing the vibration mass [M] of the foundation a more effective vibration control measure; at low frequencies, the vibration displacement is relatively large, making increasing the foundation stiffness [K] a more effective vibration control measure; and at medium frequencies, especially near the resonance frequency, damping of the foundation is a more effective vibration control measure. Therefore, based on the fundamental principles of vibration dynamics and the vibration characteristics of the shaking table, a comprehensive vibration control method targeting mass, stiffness, and damping within different frequency ranges must be adopted to achieve the purpose of vibration control.

[0013] Large shaking tables, with their complex table dimensions and equipment, require substantial underground space for the table, actuators, hydraulic power and control equipment, and oil cooling systems. Achieving solid rigidity in the foundation is impossible, especially for ultra-large shaking tables located in soft soil areas where the foundation's natural frequency is relatively low. Controlling foundation vibration solely by increasing the ratio of reinforced concrete foundation mass to vibrating mass is uneconomical, and some vibration control parameters are difficult to achieve by simply increasing foundation mass. Therefore, vibration control requires a comprehensive approach considering ground stiffness, foundation damping, and foundation quality.

[0014] Third, determine the key points for foundation quality vibration control.

[0015] The working principle of a shaking table is that the table body is connected to the foundation via actuators, and the inertial force generated by the accelerated motion of the table body reacts with the foundation. Currently, the main way to control the vibration of the shaking table foundation is to increase the mass of the foundation, with the principle of vibration control being that the ratio of the foundation mass to the vibrating mass reaches a certain level.

[0016] According to Newton's second law, the relationship between the vibration load F borne by the foundation, the vibrating mass (m), and the vibration acceleration (a) is: F = ma. The foundation vibration output is directly related not only to the vibrating mass but also to the peak vibration acceleration. Traditional small and medium-sized vibration tables have low actuator output, and the peak vibration acceleration is often less than 1.0g. Controlling the ratio of the foundation mass to the vibrating part mass to a certain level is sufficient to meet vibration control requirements. However, for large vibration tables with peak vibration acceleration greater than 1.0g, controlling the ratio of the foundation weight to the maximum vibration output is more scientifically sound.

[0017] Fourth, determine the key points for foundation stiffness vibration control.

[0018] Based on the vibration characteristics of large shaking tables, especially low-frequency vibrations, foundation stiffness is the primary method for vibration control. The main methods to improve foundation stiffness include increasing foundation depth, foundation treatment, or using pile foundations. For large shaking tables on medium-soft soil, pile foundations are generally used. The dynamic stiffness of pile foundations does not increase with increasing pile length; rather, the elasticity of the pile itself must be considered. Once the pile length reaches a certain point, the dynamic stiffness of the pile foundation no longer increases and becomes constant. According to the "elastic rod" theory of pile foundations, the vertical dynamic stiffness k of the pile foundation... pz Calculation formula:

[0019]

[0020] In the formula

[0021] k p k τ k s These are the compressive stiffness of the pile itself, the shear stiffness of the pile and the surrounding soil, and the compressive stiffness of the foundation soil at the pile tip.

[0022] For the medium-soft soil at this site, the stiffness of the pile itself is much greater than the stiffness of the soil at the pile tip, and β is approximately equal to 0. Equation 1 can be simplified to the following equation:

[0023] k pz ≈λk p thλ

[0024] From the above formula, it can be seen that when λ is greater than or equal to 2, thλ is close to 1, and the vertical dynamic stiffness k of the pile foundation is... pz No more increases, at this point

[0025] Substituting the relevant parameters into the above formula, the simplified result is the following formula for the reasonable length-to-diameter ratio i of the dynamic foundation pile: In the formula, E is the elastic modulus of the pile concrete, and D is the pile diameter. It is the weighted average of the shear stiffness coefficients of the soil around the pile within the pile body area.

[0026] Fifth, determine the key points for damping vibration control of the base group.

[0027] Damping is a crucial parameter for controlling the vibration of dynamic foundations, especially for large-scale seismic simulation vibration test benches in medium-soft soil conditions. At different resonant frequencies, foundation damping plays a major controlling role. For large shaking table foundations, the damping of the foundation mainly comes from the damping of the subgrade. The main factors affecting subgrade damping are: the larger the foundation base area, the greater the damping; the greater the base pressure, the smaller the damping; and the greater the ratio of foundation depth to foundation size, the greater the increase in damping. To effectively utilize subgrade damping, the ratio of foundation depth (h) to the equivalent radius (b) of the foundation base should be controlled to be no greater than 0.6, thus better leveraging the role of subgrade damping.

[0028] Based on the above research, this invention proposes a method for controlling the foundation vibration of large shaking tables, especially extra-large earthquake simulation shaking test tables located in medium-soft soil areas.

[0029] More specifically, according to one aspect of the present invention, a method for controlling the vibration of a large shaking table foundation is provided, specifically comprising:

[0030] 1. A method for controlling the vibration of a large shaking table foundation, characterized by comprising:

[0031] S101. Obtain functional requirements and vibration performance parameters of a large shaking table, including maximum acceleration;

[0032] S102. Based on the data from step S101, analyze the vibration characteristics and characteristic parameters of the large shaking table, and determine the target values ​​for foundation vibration displacement, velocity, and acceleration control at different frequencies according to the functional requirements and environmental conditions of the large shaking table; and determine the foundation selection, including determining the foundation depth and foundation bottom area.

[0033] S103. Determine the foundation quality indicators based on the maximum acceleration value of the large vibration table, including the foundation mass (m). j ) and the maximum movable mass of a large shaking table (m d Ratio index m j / m d and the gravity W of the foundation of the large shaking table j With the maximum output F of the large shaking table d Ratio index W j / F d When the maximum acceleration under full load is no greater than 1.0g, m j / m d ≥40; When the maximum acceleration under full load is greater than 1.0g, W j / F d ≥30 and m j / m d ≥40;

[0034] S104. Determine whether the foundation quality in S102 meets the index value in S103 above. If it does, proceed to step S107. If it does not, determine the extension of the basement that forms an integral foundation around the foundation in S102, taking into account the space requirements of the hydraulic power equipment of the vibration table. To ensure the vertical dynamic stiffness of the extension, control the width of the extension to not exceed the foundation depth.

[0035] S105. Determine whether the overall combined foundation based on S104 meets the target value of S103. If it does, proceed to step S107. If it does not, use the interior space of the basement in the extended part to fill with counterweight material to increase the total mass of the overall structure and ensure the stiffness of the surrounding extension until the total mass of the overall structure meets the target value of S103.

[0036] S106. Conduct a preliminary analysis of the basic dynamics to determine whether the target value of S102 is met. If it is met, proceed to step S107. If it is not met, use a pile foundation. Based on the engineering geological data, select a reasonable pile end bearing layer and initially determine the pile length.

[0037] S107. Perform a dynamic analysis of the foundation based on the force spectrum of the vibration table actuator to determine whether the various vibration output indicators of the foundation meet the limit requirements of S102. If not, return to S102 and re-determine the foundation type, such as increasing the foundation bottom area or increasing the foundation depth, until the target value requirements of S102 are met.

[0038] According to an embodiment of the present invention, the data further includes the dimensions of the vibration test bench and the mounting pit, the maximum load, the vibration direction and peak acceleration, the operating frequency, and the vibration table function curve.

[0039] According to an embodiment of the present invention, in step S102, the control target values include: when the vibration frequency is lower than 5 Hz, controlling the maximum displacement of the foundation not to exceed 0.16 mm; when the vibration frequency is higher than 20 Hz, controlling the maximum acceleration not to exceed 1.2 m / s 2 ; when the vibration frequency is between 10 Hz and 50 Hz, controlling the maximum speed not to exceed 10 mm / s 2 .

[0040] According to an embodiment of the present invention, the foundation embedment depth and the foundation bottom area are initially determined according to the size of the installation foundation pit, and the ratio (embedment ratio) of the foundation embedment depth (h) to the equivalent radius (b) of the foundation bottom surface is controlled so that h / b ≤ 0.6.

[0041] According to an embodiment of the present invention, to achieve the rigid target, the thickness of the pit bottom slab is not less than 1 / 3 of the width of the foundation pit and not less than 2 m at the same time, and the thickness of the surrounding wall is not less than 1 / 4 of the length of the foundation pit and not less than 2 m at the same time.

[0042] According to an embodiment of the present invention, for the large shaking table foundation in a medium-soft soil site, when the vibration frequency f ≤ 5 Hz, it is controlled according to low frequency to increase the foundation stiffness; when the vibration frequency f ≥ 20 Hz, it is controlled according to high frequency to increase the foundation mass; when 5 Hz < f < 20 Hz, it is controlled according to medium frequency, and comprehensive measures of increasing the damping of the foundation group, the foundation stiffness, and the vibration mass mainly by increasing the damping of the foundation group are taken.

[0043] According to an embodiment of the present invention, the large shaking table foundation vibration control method further includes, in step S109, based on S105, performing a static calculation check on the foundation, and correcting and refining the foundation design scheme.

[0044] According to an embodiment of the present invention, in order to give full play to the stiffness and damping of the pile foundation, using the elastic rod theory, the long diameter ratio i of the pile foundation is controlled as follows:

[0045]

[0046] In the formula, E is the elastic modulus of the pile body concrete, and D is the pile body diameter; is the weighted average value of the shear stiffness coefficient of the soil around the pile within the pile body range;

[0047] According to another aspect of the present invention, there is provided a large shaking table foundation vibration control system, including: one or more processors; and a memory, the memory stores instructions executable by the one or more processors, and the instructions cause the system to execute the method according to any one of claims 1 to 7.

[0048] Compared with the prior art, the beneficial effects of the present invention are:[[]]

[0049] This invention addresses the functional requirements of the shaking table and the surrounding environment, clearly defining scientific and reasonable vibration control objectives. It adopts comprehensive vibration control measures from various aspects, including the foundation quality, foundation stiffness, and foundation damping, forming a complete set of vibration control methods for large-scale shaking table foundations. This effectively controls the vibration of the shaking table foundation while improving the quality of the building environment where the shaking table is located, enhancing the comfort of users, and ensuring the safety of facilities and buildings. It has significant socio-economic benefits and engineering application value.

[0050] The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0051] Some specific embodiments of the invention will be described in detail below by way of example and not limitation, with reference to the accompanying drawings. The objectives and features of the invention will become more apparent from the following description taken in conjunction with the accompanying drawings. In the drawings:

[0052] Appendix Figure 1 This is a flowchart of a vibration control method for a large shaking table foundation according to an embodiment of the present invention;

[0053] Appendix Figure 2 A schematic diagram of the foundation layout structure of a large shaking table according to an embodiment of the present invention; and

[0054] Appendix Figure 3 This is a schematic diagram of the target value for vibration control of a large shaking table foundation according to an embodiment of the present invention. Detailed Implementation

[0055] To clearly illustrate the present invention, further description is provided below with reference to examples. The following description is merely exemplary in nature and is not intended to limit the application or use of the present invention.

[0056] It should be understood that some of the basic technical concepts involved in this invention, such as finite element modeling, equivalent boundary elements, modal analysis, static and dynamic analysis, etc., are known in themselves. Therefore, this paper focuses on how to combine these basic technologies to control the vibration of large shaking table foundations.

[0057] Appendix Figure 1 A flowchart of a vibration control method for a large shaking table foundation according to an embodiment of the present invention is attached. Figure 2 A schematic diagram of the foundation layout structure of a large shaking table according to an embodiment of the present invention is attached. Figure 3 This is a schematic diagram illustrating the target values ​​for vibration control of a large shaking table foundation according to an embodiment of the present invention. The invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0058] Reference Appendix Figure 1-3The vibration control method for a large shaking table foundation in the implementation plan may include the following steps:

[0059] First, the basic vibration characteristic parameters required for the shaking table's functional requirements were obtained. Specifically, the shaking table is a large-scale earthquake simulation vibration test bench with a table size of 20m x 15m, a maximum load of 1000t, three-axis six-degree-of-freedom, a maximum displacement of ±1.0m, a maximum acceleration of 1.5g, and an operating frequency of 0.1–30Hz. The maximum displacement, velocity, and acceleration performance curves under each frequency condition are shown below. Figure 3 .

[0060] Based on the functional requirements and environmental conditions of the shaking table, the control targets for the foundation apex are determined as follows: when the vibration frequency is below 5Hz, the maximum displacement of the foundation should not exceed 0.25mm; when the vibration frequency is above 20Hz, the maximum acceleration should not exceed 1.0m / s². 2 When the vibration frequency is between 10Hz and 20Hz, the maximum speed should be controlled to not exceed 10mm / s. 2 .

[0061] The installation dimensions of the vibration table are 25m x 20m x 10m (length x width x depth). The thickness of the foundation slab is determined to be no less than 20m / 4 = 5m. Taking the slab thickness as 5m, the foundation depth is 10m + 5m = 15m. Based on the principle that the depth-to-depth ratio should not exceed 0.6, the minimum length of the foundation bottom edge is 15m / 0.6 = 25m.

[0062] Next, the dynamic parameters of the large shaking table are analyzed. The maximum acceleration of the shaking table under full load is 1.5g, and the ratio of the weight of the shaking table foundation to the maximum output force of the actuator must be no less than 30 times. According to Newton's second and third laws, the maximum output force of the actuator is 1000t x 1.5 x 10 = 15000kN, and the target value of the weight of the large shaking table foundation is 15000kN x 30 = 450000kN.

[0063] Based on the dimensions of the large shaking table and the arrangement of components such as actuators, the core rigid block foundation of the shaking table is determined. The thickness of the walls surrounding the foundation pit is 20m / 4 = 5m, which is taken as 5m. Comprehensive analysis determines the length x width x depth of the core rigid zone of the foundation to be 35m x 30m x 15m.

[0064] Based on the aforementioned core rigid block, the calculated foundation weight of the rigid area is 268,750 kN, which does not meet the minimum foundation weight requirement. Therefore, considering the functional requirements of the equipment around the rigid block, an extended basement is constructed around the core rigid area to form a unified foundation. The width of the extended portion is controlled to be no greater than the foundation depth, and the width of the extended basement is set at 12 m to ensure the vibration stiffness of the extended portion.

[0065] Based on the overall combined foundation formed by the aforementioned core rigid base block and the surrounding extended basement roof and floor slabs, the overall foundation gravity does not meet the target value. By using plain concrete counterweight material to fill the cavity of the surrounding extended basement, the total gravity is calculated to be approximately 900,000 kN, which meets the target value requirement.

[0066] Subsequently, based on the integrated foundation, preliminary dynamic calculations were performed. The low-frequency vibration displacement did not meet the target value, so increasing the foundation stiffness was the primary control measure. Based on site conditions, pile foundations were chosen. The site's engineering geological conditions were extracted; within the exploration area, the soil consisted mainly of cohesive soil, silt, and silty sand, and the soil type was classified as medium-soft soil. Based on the soil layer distribution and the bearing stratum at the pile tip, the pile length was preliminarily determined. To fully utilize the pile foundation's stiffness and damping, the elastic rod theory was used to control a reasonable pile length, as shown in the following formula:

[0067]

[0068] In the formula, E is the elastic modulus of the pile concrete, and the strength grade of the pile concrete is C30, E = 3.0 x 10⁻⁶. 7 kN / m 2 D is the pile diameter, initially set at 0.7m. The weighted average of the shear stiffness coefficients of the soil surrounding the pile within the pile body area; for this site, it is 4x10. 4 kN / m 3 The calculated reasonable length-to-diameter ratio is i = 32. Using a pile length of 21m, 21m / 0.7m = 28, which meets the length-to-diameter ratio requirement. This allows for full utilization of the pile foundation's stiffness and damping.

[0069] Finally, dynamic analysis and evaluation of the overall combined foundation including pile foundation were carried out under various frequency conditions, and all vibration output indicators of the foundation met the target limit requirements.

[0070] An embodiment of the present invention also provides a vibration control system for a large shaking table foundation, the system including one or more processors; and a memory storing instructions executable by the one or more processors, the instructions causing the system to perform the method according to the present invention.

[0071] The vibration control method for large shaking table foundations proposed in this embodiment is simple, reasonable, technically feasible, and easy to implement. While ensuring that the large shaking table foundation has sufficient strength, stiffness, stability, and durability, it effectively controls the vibration of the shaking table foundation and its impact on the external environment, and has high engineering value.

[0072] While the present invention has been described with reference to specific illustrative embodiments, it is not limited to these embodiments but only to the appended claims. Those skilled in the art will understand that modifications and alterations can be made to the embodiments of the invention without departing from the scope and spirit of the invention.

Claims

1. A method for controlling the vibration of a large shaking table foundation, characterized in that... Including: S101. Obtain the functional requirements and vibration performance parameter data of the large vibration table, including the maximum acceleration; S102. Based on the data in step S101, analyze the vibration characteristics and characteristic parameters of the large vibration table, and determine the control target values of the basic vibration displacement, velocity, and acceleration at different frequencies according to the functional requirements and environmental conditions of the large vibration table; And determine the foundation type selection, including determining the foundation embedment depth and the foundation bottom area; S103. Determine the foundation quality indicators based on the maximum acceleration value of the large vibration table, including the foundation mass m. j With the maximum movable mass m of the large shaking table d Ratio index m j / m d and the gravity W of the foundation of the large shaking table j With the maximum output F of the large shaking table d Ratio index W j / F d When the maximum acceleration under full load is no greater than 1.0g, m j / m d ≥40; When the maximum acceleration under full load is greater than 1.0g, W j / F d ≥30 and m j / m d ≥40; S104. Judge whether the foundation quality in S102 meets the index values in S103 above. If it meets, proceed to step S107; if it does not meet, around the foundation in S102, combined with the space requirements of the vibration table hydraulic power equipment, determine the extended part including the basement that forms an integral combined foundation with the foundation, and to ensure the vertical dynamic stiffness of the extended part, control the width of the extended part not to be greater than the foundation embedment depth; S105. Judge whether the integral combined foundation based on S104 meets the target value of S103. If it meets, proceed to step S107; if it does not meet, use the internal space of the basement in the extended part to fill with counterweight materials to increase the total mass of the overall structure and ensure the stiffness of the surrounding extension until the total mass of the overall structure meets the target value of S103; S106. Conduct a preliminary dynamic analysis of the foundation to judge whether it meets the target value of S102. If it meets, proceed to step S107; if it does not meet, adopt a pile foundation, and according to the engineering geological data, select a reasonable pile tip bearing layer and preliminarily determine the pile length; S107. Based on the actuator force spectrum of the vibration table, conduct a dynamic analysis of the foundation to judge whether the vibration output indexes of the foundation meet the limit requirements of S102. If they do not meet, return to S102 and re-determine the foundation type selection until the requirements of the target value of S102 are met.

2. The vibration control method for a large shaking table foundation according to claim 1, characterized in that, The said data also includes the dimensions of the vibration test table surface and the installation foundation pit, the maximum load, the vibration direction and peak acceleration, the working frequency, and the function curve of the vibration table.

3. The vibration control method for a large shaking table foundation according to claim 1, characterized in that, In step S102, the control target values ​​include: controlling the maximum displacement of the foundation to be no greater than 0.16 mm when the vibration frequency is below 5 Hz; and controlling the maximum acceleration to be no greater than 1.2 m / s² when the vibration frequency is above 20 Hz. 2 When the vibration frequency is between 10Hz and 50Hz, the maximum speed should be controlled to not exceed 10mm / s. 2 .

4. The vibration control method for a large shaking table foundation according to claim 2, characterized in that, According to the dimensions of the installation foundation pit, preliminarily determine the foundation embedment depth and the foundation bottom area, and control the ratio of the foundation embedment depth h to the equivalent radius b of the foundation bottom surface (embedment ratio) index to control h / b ≤ 0.

6.

5. The vibration control method for a large shaking table foundation according to claim 2, characterized in that: To achieve the rigid target, the thickness of the pit bottom slab is not less than 1 / 3 of the width of the foundation pit and not less than 2m at the same time, and the thickness of the surrounding wall is not less than 1 / 4 of the length of the foundation pit and not less than 2m at the same time.

6. The vibration control method for a large shaking table foundation according to claim 1, characterized in that, For the large vibration table foundation in the medium-soft soil site, when the vibration frequency f ≤ 5Hz, it is controlled according to the low frequency to increase the foundation stiffness; when the vibration frequency f ≥ 20Hz, it is controlled according to the high frequency to increase the foundation mass; when 5Hz < f < 20Hz, it is controlled according to the medium frequency, and comprehensive measures of increasing the group damping, foundation stiffness, and vibration mass mainly based on increasing the group damping are taken.

7. The vibration control method for a large shaking table foundation according to claim 1, characterized in that, It also includes in step S109, based on S105, conduct a static calculation check of the foundation and modify and refine the foundation design scheme.

8. The vibration control method for a large shaking table foundation according to claim 1, characterized in that, In step S106, to give full play to the stiffness and damping of the pile foundation, using the elastic rod theory, control the pile length-diameter ratio i as follows: In the formula, E is the elastic modulus of the pile concrete, and D is the pile diameter; It is the weighted average of the shear stiffness coefficients of the soil surrounding the pile within the pile body area.

9. A vibration control system for a large shaking table foundation, characterized in that, Including: One or more processors; And a memory, the memory stores instructions executable by the one or more processors, and the instructions enable the system to execute the method according to any one of claims 1 to 8.

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