Active prevention and control system for sand foundation damage under earthquake action and construction method of active prevention and control system

Abstract

The invention discloses an active prevention and control system for sand foundation damage under the earthquake action and a construction method of the active prevention and control system. The system comprises a main body structure pressed into a sand stratum, earthquake frequency obtaining units annularly distributed on the periphery of the main body structure and a power supply unit on the top. The main body structure comprises an analysis feedback unit, an execution unit and a reinforcement unit, the analysis feedback unit receives seismic frequency data and generates an anti-phase waveform instruction, and the execution unit vibrates to weaken the seismic action; and under the high-strength earthquake working condition, the earthquake load effect rises, the pore water pressure rises to the preset threshold value, the reinforcing units are triggered, the reinforcing grout flows out of the honeycomb grid-shaped side wall, and grouting reinforcement of the foundation is achieved. The construction method comprises the steps of site exploration, drilling operation, unit layout, structure lowering, connection debugging and effect detection. By means of the principle of interference reduction, through the synergistic effect of active vibration reduction and instant reinforcement, full-stage prevention and control of sand liquefaction are achieved, the response speed is high, and the reinforcement effect can be achieved to the maximum extent.

Description

Technical Field

[0001] This invention relates to the field of seismic protection technology in geotechnical engineering, and in particular to an active prevention and control system for sandy soil foundation damage under earthquake loading and its construction method. Background Technology

[0002] In recent years, with the widespread application of land reclamation technology, the development and utilization of desert fringe areas, and the engineering transformation of complex terrain along rivers and coastlines, the number of buildings constructed on sandy soil foundations has been rapidly increasing. Earthquake-induced sandy soil damage directly threatens the structural integrity and bearing capacity of the foundation. Therefore, conducting research on the suppression mechanism of sandy soil foundation damage under earthquakes and developing scientific and effective reinforcement technologies has significant engineering practical value and real-world significance.

[0003] The damage to sandy soil foundations under earthquake loading mainly manifests as soil liquefaction, subsidence, and shear failure. Numerous mitigation measures have been developed in the engineering field. For example, patent CN 202411483452X uses a dynamic compaction machine to increase the density of the sand, but this method involves significant vibration and is not suitable for fine sand. Patent CN2021109651506 utilizes cement grouting to strengthen the cementation of the sand; patent CN2014100017784 uses cement-soil piles to encircle the foundation soil, increasing deformation constraints. However, chemical grouting is costly, and the strength gain of cement-soil is greatly affected by temperature and humidity, requiring controlled curing conditions. Regarding seismic isolation and damping measures, patent CN2021110883006 proposes a fence-type seismic isolation structure and its design method. This method reduces the impact of seismic loads on the engineering site by setting several barrier units around the perimeter. However, this anti-liquefaction barrier method is difficult to construct and costly. Alternatively, flexible materials can be laid between the foundation and the ground to absorb seismic energy using the energy-dissipating properties of the flexible materials. However, the stability and durability of the seismic isolation layer made of flexible materials are difficult to control.

[0004] The above-mentioned reinforcement methods are all passive defenses against the damage to sandy soil foundations under earthquake action. They cannot adaptively and actively weaken the damage to sandy soil foundations caused by earthquake action according to the intensity of the earthquake. Furthermore, the reinforcement measures are present from the time of construction, and their effectiveness gradually weakens as the time of completion increases, so they cannot achieve the best protection effect when an earthquake occurs. Summary of the Invention

[0005] Objective of this invention: The objective of this invention is to provide an active prevention and control system that can adaptively suppress the damage to sandy soil foundations based on earthquake intensity. This system can also trigger reinforcement of the sandy soil foundation under high-intensity earthquake conditions. Another objective of this invention is to provide a construction method for this active prevention and control system.

[0006] Technical Solution: The present invention discloses an active prevention and control system for sandy soil foundation damage under seismic loading, comprising a main structure embedded in the sandy soil layer, seismic frequency acquisition units arranged around the perimeter of the main structure, and a power supply unit located on top of the main structure. The main structure includes an analysis feedback unit located below the power supply unit, an execution unit located on the outer surface of the main structure, and a reinforcement unit inside the main structure. The analysis feedback unit receives data from the seismic frequency acquisition unit and generates a waveform command that matches the seismic waveform but is opposite in phase. The execution unit executes the waveform command to weaken the seismic loading. When the pore water pressure in the sandy soil layer where the main structure is located reaches a set threshold, the reinforcement unit is triggered to grout and reinforce the external sandy soil layer. The outer surface of the main structure has a honeycomb grid-like sidewall.

[0007] Based on the principle of interference cancellation, seismic frequency acquisition units distributed around the outer side of the main structure acquire and feed back data. Utilizing the changes in amplitude and phase of Rayleigh scattering light caused by fiber strain under seismic loads, a DSP chip performs high-speed sampling, filtering, and frequency domain analysis to obtain the waveform information of the seismic load. This information guides the PLC to quickly generate waveform information with the opposite phase to the seismic load. Combining factors such as geological conditions and seismic load carrier velocity, a corresponding electrical signal is generated with the support of a frequency converter. This signal then generates corresponding vibration through a vibration motor, achieving interference cancellation between the vibration waveform and the seismic waveform, thus weakening the destructive effect of seismic forces on the sandy soil strata. Simultaneously, the lower connecting structure uses unidirectional shape memory metal with pre-cut grooves on its surface. When the external pore water pressure reaches a certain threshold, the lower connecting structure expands inward to connect the self-expanding column inside and outside. The self-expanding column absorbs water, causing radial expansion and compressing the internal cavity. After reaching the threshold pressure, the side connecting structure expands outward, and reinforcing grout is injected to reinforce the external sandy soil foundation, achieving rapid repair of the sandy soil foundation after the earthquake.

[0008] Furthermore, the seismic frequency acquisition unit includes a protective layer vertically inserted around the perimeter of the main structure, an input optical fiber and an output optical fiber located within the protective layer, a light source located on the analysis feedback unit and coupled to the input optical fiber, and the output optical fiber connected to the analysis feedback unit.

[0009] Furthermore, the analysis feedback unit includes a DSP chip, a frequency converter, and a PLC that are connected one-to-one with the output optical fiber. The DSP chip aggregates the data to the PLC through the transmission module circuit, and the frequency converter receives the waveform command from the PLC and is connected to the execution unit through wires.

[0010] Furthermore, the sidewall is composed of multiple hollow hexagonal prisms, each of which includes an outwardly expanding support frame and an inner sidewall; multiple grooves are vertically opened along the sidewall, and the execution units are spaced apart in the grooves; the execution units are multiple vibration motors, which are fixedly installed in the grooves by limit bolts, and the vibration motors in each groove are connected in series.

[0011] Preferably, the power supply unit includes a power source and wires. The wires connect to the input terminal of the frequency converter, and the power supply unit, frequency converter, and execution unit are connected in series. Utilizing the characteristic changes in amplitude and phase of Rayleigh scattering light induced by fiber optic strain under seismic load, a DSP chip performs high-speed sampling, filtering, and frequency domain analysis to obtain the waveform information of the seismic load. Based on this, the PLC generates waveform information with the opposite phase to the seismic load. Combining factors such as geological conditions and seismic load velocity, a corresponding electrical signal is generated with the support of the frequency converter. This signal then generates corresponding vibration through a vibration motor, achieving interference reduction between the vibration waveform and the seismic waveform, thus weakening the destructive effect of seismic action on sandy soil strata.

[0012] Furthermore, the reinforcement unit includes a self-expanding column located at the center of the main structure and capable of radial expansion upon contact with water; a flexible membrane radiating outwards from the self-expanding column; a sealing strip connecting the flexible membrane to the sidewall; reinforcement grout located between the sidewall and the self-expanding column; a lower connecting structure that automatically opens under a set pore water pressure; and a side connecting structure for the reinforcement grout to flow out. The lower connecting structure is located at the bottom of the self-expanding column and is made of unidirectional shape memory metal with pre-cut grooves on its surface. The preset deformation direction of the lower connecting structure is inward expansion. The side connecting structure is located on the sidewall and is also made of unidirectional shape memory metal with pre-cut grooves on its surface. The preset deformation direction of the side connecting structure is outward expansion.

[0013] Both the lower and side connecting structures are made of shape memory alloy. When the pore water pressure in the external sandy soil layer reaches the preset threshold, the lower connecting structure opens inward, the self-expanding column absorbs water and expands, and squeezes the flexible membrane. The pressure difference between the inside and outside of the main structure increases. After reaching the threshold pressure, the side connecting structure deforms and opens outward, and the reinforcing grout overflows from the side connecting structure to grout and reinforce the external sandy soil foundation, and quickly deal with the sandy soil damage.

[0014] The construction method of the active prevention and control system for sandy soil foundation failure under earthquake loading, as described in this invention, includes the following steps:

[0015] S1: Site exploration, determining the location and depth of boreholes based on the actual geological survey report and construction plan, and marking the locations;

[0016] S2: Bury the casing at the predetermined location, and then carry out drilling operations. The drilling depth should not exceed the casing burial depth until the predetermined burial depth is reached.

[0017] S3: With the borehole as the center, the seismic frequency acquisition units are arranged in a ring at fixed intervals and buried or pressed into the sandy soil layer. At the same time, the assembled main structure is lowered at the borehole.

[0018] S4: Sheath the pre-reserved optical fiber outside the seismic frequency acquisition unit and reserve the connection end, pull out the borehole casing and retrieve it;

[0019] S5: Connect the fiber optic reserved connection end in the seismic frequency acquisition unit to the DSP chip input port in the analysis feedback unit, and connect the power supply unit to the external circuit.

[0020] S6: Apply vibrations of known frequency to the far end of the site, and set up a ground motion monitoring instrument to monitor the seismic state of the reinforced sandy soil site, check the installation effect of the reinforcement device, and ensure the reliability of its operation.

[0021] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0022] (1) The system innovatively introduces the principle of interference reduction in the field of suppressing earthquake damage to sandy soil foundations, breaking the limitations of traditional passive protection methods. The system can dynamically adjust the anti-damage capacity of sandy soil foundations according to the real-time intensity of seismic loads. Through the graded control mechanism, it can accurately offset the seismic wave energy under low-intensity earthquake action and significantly weaken the impact of earthquake damage under medium and high-intensity earthquake action, thereby greatly improving the overall anti-liquefaction performance of sandy soil foundations under different earthquake conditions.

[0023] (2) In the early stage of an earthquake, the real-time seismic wave parameters collected by the seismic frequency acquisition unit are analyzed and feedback units generate control commands with opposite phase to the seismic waveform, which drive the execution unit to generate corresponding vibrations. The interference of waves reduces the seismic wave energy and weakens the liquefaction inducing factors between sand particles (effective stress reduction, pore water pressure increase, etc.) from the root. Under high-intensity earthquake conditions, when the seismic load increases and the pore water pressure of the sand layer exceeds the preset safety threshold, the system automatically triggers the reinforcement unit to start grouting operations. By actively filling the sand pores, the foundation's anti-liquefaction ability is further improved. In the early stage of an earthquake, the execution unit generates opposite phase vibrations to offset the seismic wave energy and weaken the sand liquefaction inducing factors. When the earthquake intensity increases and the pore water pressure exceeds the standard, the reinforcement unit is automatically triggered to grout, forming a double protection.

[0024] (3) The reinforcement unit is intelligently controlled based on the dynamic balance relationship between the internal cavity pressure of the structure, the pore water pressure of the sandy soil layer and the hydraulic pressure of the reinforcement grout, and a precise pressure trigger threshold is preset. When the pressure reaches the set condition, the lower connecting structure and the side connecting structure undergo directional deformation and automatically open to realize the directional release of the reinforcement grout. This design can accurately avoid the problem of grout overflow in unnecessary reinforcement state under low-intensity seismic load, effectively reduce the generation of ineffective reinforcement area, ensure that the reinforcement unit can play a maximum immediate protective role at critical time, and ensure the structural stability of the sandy soil foundation. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the active prevention and control system of the present invention;

[0026] Figure 2 for Figure 1 A magnified view of a portion of point A in the middle;

[0027] Figure 3 This is a schematic diagram of the site-level layout of the active prevention and control system of the present invention;

[0028] Figure 4 This is a schematic diagram of the arrangement of the seismic frequency acquisition unit in this invention;

[0029] Figure 5 This is a schematic diagram showing the connection relationship between the analysis feedback unit and the earthquake frequency acquisition unit in this invention;

[0030] Figure 6 This is a three-dimensional schematic diagram of the analysis feedback unit in this invention;

[0031] Figure 7 This is a top view of the analysis feedback unit in this invention;

[0032] Figure 8 This is a schematic diagram of the three-dimensional structure of the reinforcement unit in this invention;

[0033] Figure 9 This is a diagram showing the positional relationship between the self-expanding column and the sidewall in this invention;

[0034] Figure 10 This is a schematic diagram of the lower through-connection structure in this invention;

[0035] Figure 11 This is a schematic diagram of the side-connection structure in this invention;

[0036] Figure 12 This is a schematic diagram of the connection between the flexible membrane and the sidewall in this invention. Detailed Implementation

[0037] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0038] The active prevention and control system of this invention mainly includes a main structure 1, a seismic frequency acquisition unit 2, a power supply unit 3, an analysis and feedback unit 4, an execution unit 5, and a reinforcement unit 6. The main structure 1 is cylindrical, and its pipe diameter can be appropriately adjusted according to the volume of the injected reinforcement grout. The length of the main structure 1 can be reasonably controlled according to the depth of the sandy soil layer. Figure 1 , Figure 4 As shown, the seismic frequency acquisition units 2 are arranged in a ring around the perimeter of the main structure. A single main structure 1 and the surrounding seismic frequency acquisition units 2 together form a unit cell in the field. For example... Figure 3 As shown, the fortification range of the sandy soil foundation area is divided according to the construction volume of the superstructure. The fortification range is not less than the coverage area of ​​the superstructure. Within the fortification range, unit structures should be arranged in a matrix. This matrix arrangement disrupts the existing propagation path of seismic loads in the sandy soil layer and weakens the seismic impact on the sandy soil layer to a certain extent.

[0039] like Figure 1 , Figure 5 As shown, the seismic frequency acquisition unit 2 includes a protective layer 21, an input optical fiber 22, an output optical fiber 23, and a light source 24. The light source 24 is mounted on the main structure 1 and can be a laser source, typically in TEM00 mode, to achieve efficient light transmission. The input and output optical fibers are actually the two ends of the same optical fiber, divided into output fiber 23 and input fiber 22 based on the difference between the output and input light sources. Single-mode fiber is used here, which, compared to multimode fiber, offers advantages such as high bandwidth, low signal loss, support for long-distance information transmission, and low dispersion, effectively ensuring signal accuracy and integrity during transmission. The optical fiber is covered by a protective layer 21, typically a multi-segment steel metal shell vertically inserted around the perimeter of the main structure 1. This multi-ring structure has an inner ring diameter matching the maximum diameter of the optical fiber. This structure not only effectively protects the internal optical fiber but also ensures real-time sensing of external environmental changes, guaranteeing the accuracy, timeliness, and effectiveness of the acquired data. The light source 24 emits continuous and stable probe light into the input optical fiber 22. When the probe light propagates in the optical fiber, it generates Rayleigh scattering, forming backscattered Rayleigh light, which returns to the analysis feedback unit 4 along the output optical fiber.

[0040] The power supply unit 3 is located in the uppermost area of ​​the main structure 1, and the analysis feedback unit 4 is located below it. Under normal conditions, the power supply unit 3 supplies power to the light source 24 of the seismic frequency acquisition unit 2, the analysis feedback unit and the various structures in the execution unit 5 through the conductor 31. Under special conditions, it switches to the reserve power supply. The power supply and the reserve power supply are connected in parallel.

[0041] like Figures 5-7As shown, the analysis feedback unit 4 includes a DSP chip 41, a frequency converter 42, a PLC 43, and a transmission module circuit 44, all located on the same plane. Multiple DSP chips 41 are present, each corresponding to an output optical fiber 23, avoiding the problem that a single DSP chip cannot process multiple sets of data in parallel. The PLC 43 is located at the center of the plane, receiving signals from each DSP chip. The input ports of the DSP chips 41 are independently connected to the optical fibers via patch cords. Using their built-in logic circuits, they convert the input analog signals into digital signals, perform filtering and frequency domain analysis, and transmit this information to the PLC 43 through the corresponding transmission module circuit 44 on the circuit board. This generates a digital signal with an opposite phase waveform, which is then transmitted to the frequency converter 42 via RS485 communication. The frequency converter 42 is located between the DSP chips and the PLC, with a one-to-one correspondence between the DSP chips and the frequency converter. The frequency converter is connected to the power supply unit via wire 31, and its output is connected to the vibration motor 51 via wire 31. Wire 31 connects the power supply unit 3, the frequency converter 42, and the execution unit 5 in series. This structural layout realizes the conversion of the phase-opposite waveform digital signal generated by the PLC into an electrical signal, ensuring that the execution unit 5 can generate the preset vibration.

[0042] like Figure 1 , Figure 2 As shown, the execution unit 5 consists of multiple vibration motors 51, which are fixedly mounted on the outer surface of the main structure 1. The outer surface of the main structure 1 has a honeycomb grid-shaped sidewall 11, with multiple grooves 12 vertically formed along the sidewall 11. Vibration motors in each groove 12 are connected in series. The cross-sectional shape of the groove 12 is approximately square, with dotted grooves near the inner edge. The width and depth of the grooves are consistent with the width and height of the vibration motors. The lower dotted grooves are used for cable laying. The sidewalls of the grooves have fixing holes, and the vibration motors 51 are fixed in the grooves with limiting bolts to effectively constrain them and prevent them from dislodging due to vibration. The spacing between adjacent vibration motors along the same longitudinal line is the same, and all vibration motors are arranged in a matrix. After the vibration motors along the same longitudinal line are connected in series, they are snapped into designated positions and fixed to the honeycomb grid-shaped sidewall 11 with the help of clips. The series connection mode ensures that the current magnitude and frequency of each motor are consistent, and ensures that the vibration intensity and vibration frequency generated by the vibration motor 51 are uniform. The matrix arrangement ensures that the execution unit 5 can generate vibration of sufficient intensity, providing protection against the impact of seismic loads.

[0043] like Figure 6-12As shown, the reinforcement unit 6 includes a self-expanding column 61 located at the center of the main structure 1 and capable of radial expansion upon contact with water; a flexible membrane 62 radiating outwards from the self-expanding column; a sealing strip 63 connecting the flexible membrane to the sidewall; a reinforcement grout 64 located between the sidewall and the self-expanding column; a lower connecting structure 65 that automatically opens under a set pore water pressure; and a side connecting structure 66 for the reinforcement grout to flow out. The main structure not only has honeycomb grid-like sidewalls 11, but its bottom surface is also honeycomb grid-like. The sidewalls 11 are composed of multiple hollow hexagonal columns sharing the same edge. Each three-dimensional regular hexagonal unit includes an outwardly expanding support frame 111 and an inner sidewall 112. This structural form is adapted to sandy soil foundations, allowing for close contact with the surrounding sandy soil after the casing is removed, increasing the contact area between the sandy soil and the structure, thereby enhancing the energy absorption capacity of the main structure 1 and reducing the probability of sandy soil foundation failure under strong earthquake conditions to a certain extent.

[0044] The self-expanding column 61 is located at the center of the space formed by the sidewall 11, i.e., the center of the main structure 1. It is made of water-absorbing and swelling materials such as water-absorbing resin and water-absorbing and swelling rubber. After contact with water, it absorbs water and undergoes radial expansion under the synergistic effect of the hydrophilic components and non-polar groups in the water-absorbing and swelling material. A flexible membrane 62 is wrapped around the self-expanding column and is in close contact with it. The flexible membrane is connected to the sidewall 11 through the sealing strip 63, forming multiple relatively independent inner cavities. The reinforcing grout 64 is stored in these cavities, which isolate the internal reinforcing grout from the outside under normal conditions and prevent the reinforcing grout from constraining the self-expanding column 61, ensuring that the self-expanding column can undergo predetermined radial expansion under water absorption conditions. The reinforcing grout 64 can be made of polyurethane-based reinforcing material. When injecting into the inner cavity, vacuum injection is achieved through the injection port at the top of the sidewall 11. This type of reinforcing grout can be stored in a fluid state under vacuum.

[0045] The lower connecting structure 65 is arranged at the lower part of the self-expanding column 61, and its inner side is connected to the self-expanding column. The aperture size is the same as that of the self-expanding column in its unexpanded state. It is made of unidirectional shape memory metal with pre-cut grooves 67 on its surface. Under triggering conditions, it unfolds unidirectionally along the pre-cut grooves towards the main structure 1 to realize the inward opening of the lower connecting structure. The preset deformation critical value of the shape memory alloy seal can be adjusted as needed. The alloy composition can be adjusted to change the critical value and match the pore water pressure threshold corresponding to different sand types. The side connecting structure 66 is provided on part of the inner sidewall 112. The surface of the inner sidewall has a unidirectional shape memory metal structure with pre-cut grooves 67. Under triggering conditions, it unfolds unidirectionally along the pre-cut grooves away from the main structure 1 to realize the outward opening of the side connecting structure. The aperture size of the side connecting structure 66 is consistent with the hexagonal grid formed by the support frame 111. This structural arrangement fully utilizes the environmental changes caused by the rise in pore water pressure in sandy soil strata under earthquake conditions. Combined with the inherent properties of unidirectional shape memory alloy, it enables the self-opening of the shape memory alloy seal under fixed conditions, providing conditions for the subsequent water absorption and expansion process of the self-expanding column and the release of the reinforcing grout.

[0046] Based on the above description, the workflow of the proactive prevention and control system is as follows:

[0047] (1) After the sandy soil layer is subjected to earthquake action, the backscattering of the laser in the optical fiber changes in the earthquake frequency acquisition unit 2 surrounding the main structure 1, and the simulated signal is transmitted to the analysis feedback unit 4.

[0048] (2) The DSP chip 41 in the analysis feedback unit 4 converts the transmitted analog signal into a digital signal through its internal sampling and quantization, filters the invalid vibration and noise waveforms, and outputs it to the PLC 43 in the form of a digital signal.

[0049] (3) The PLC performs phase change on the digital signal input by the DSP chip according to the predetermined programming, and processes it to obtain a waveform signal with the same frequency and amplitude as the original seismic waveform but opposite phase, and connects it to the frequency converter 42 through RS485 communication.

[0050] (4) The frequency converter 42 is connected in series with the power supply and the vibration motor 52. According to the signal source transmitted by RS485, it generates a corresponding electrical signal to control the vibration motor 51 to generate corresponding frequency vibration, thereby reducing the interference between the vibration waveform and the seismic waveform and weakening the damage of the seismic action to the sandy soil layer.

[0051] (5) When the earthquake intensity increases and the external pore water pressure reaches a certain threshold, the lower connecting structure 65 opens inward, the self-expanding column 61 absorbs water and expands radially, squeezing the flexible membrane, the pressure difference between the inside and outside of the main structure increases, and when a certain pressure is reached, the shape memory alloy seal at the side connecting structure 66 deforms and opens outward, and releases the reinforcing grout 64 to reinforce the surrounding sandy soil layer and reduce the damage caused by earthquake load.

[0052] The present invention also provides a construction method for the active prevention and control system, comprising the following steps:

[0053] S1: Site exploration, determining the location and depth of boreholes based on the actual geological survey report and construction plan, and marking the locations;

[0054] S2: Bury the casing at the predetermined location, and then carry out drilling operations. The drilling depth should not exceed the casing burial depth until the predetermined burial depth is reached.

[0055] S3: With the borehole as the center, the seismic frequency acquisition unit 2 is arranged in a ring at fixed intervals and buried or pressed into the sandy soil layer. At the same time, the assembled main structure 1 is lowered at the borehole.

[0056] S4: Sheath the external optical fiber of the seismic frequency acquisition unit 2 and reserve the connection end, pull out the borehole casing and recycle it.

[0057] S5: Connect the fiber optic reserved connection end in the seismic frequency acquisition unit 2 to the DSP chip input port in the analysis feedback unit 4, and connect the power supply unit 3 to the external circuit.

[0058] S6: Apply vibrations of known frequency to the far end of the site, and set up a ground motion monitoring instrument to monitor the seismic state of the reinforced sandy soil site, check the installation effect of the reinforcement device, and ensure the reliability of its operation.

Claims

1. A proactive prevention and control system for sandy soil foundation damage under earthquake loading, characterized in that, The system includes a main structure (1) embedded in the sandy soil layer, a seismic frequency acquisition unit (2) arranged around the periphery of the main structure (1), and a power supply unit (3) set on the top of the main structure (1). The main structure (1) includes an analysis feedback unit (4) located below the power supply unit (3), an execution unit (5) located on the outer surface of the main structure (1), and a reinforcement unit (6) inside the main structure (1). The analysis feedback unit (4) receives data from the seismic frequency acquisition unit (2) and generates a waveform command that matches the seismic waveform and is opposite in phase. The execution unit (5) executes the waveform command to weaken the seismic effect. When the pore water pressure in the sandy soil layer where the main structure (1) is located reaches a set threshold, the reinforcement unit (6) is triggered to grout and reinforce the external sandy soil layer. The outer surface of the main structure (1) is a honeycomb grid-shaped sidewall (11).

2. The active prevention and control system according to claim 1, characterized in that, The earthquake frequency acquisition unit (2) includes a protective layer (21) vertically inserted around the outer perimeter of the main structure (1), an input optical fiber (22) and an output optical fiber (23) located in the protective layer (21), and a light source (24) located on the analysis feedback unit (4) and coupled to the input optical fiber (22). The output optical fiber (23) is connected to the analysis feedback unit (4).

3. The active prevention and control system according to claim 1, characterized in that, The analysis feedback unit (4) includes a DSP chip (41) connected to the output optical fiber (23) one by one, a frequency converter (42), and a PLC (43) that can generate waveform instructions that match the earthquake waveform and are opposite in phase. The DSP chip (41) aggregates data to the PLC (43) through the transmission module circuit (44). The frequency converter (42) receives the waveform instructions from the PLC (43) and is connected to the execution unit (5) through the wire (31).

4. The active prevention and control system according to claim 1, characterized in that, The power supply unit (3) includes a power source and a wire (31). The input terminal of the frequency converter (42) is connected through the wire (31). The wire (31) connects the power supply unit (3), the frequency converter (42), and the execution unit (5) in series.

5. The active prevention and control system according to claim 1, characterized in that, The sidewall (11) is composed of multiple hollow hexagonal prisms with common sides. Each hollow hexagonal prism includes an outwardly expanding support frame (111) and an inner sidewall (112). Multiple grooves (12) are vertically opened along the sidewall (11), and the execution units (5) are spaced apart in the grooves (12).

6. The active prevention and control system according to claim 1, characterized in that, The execution unit (5) consists of multiple vibration motors (51). The vibration motors (51) are fixedly installed in the groove (12) by limiting bolts, and the vibration motors in each groove (12) are connected in series.

7. The active prevention and control system according to claim 1, characterized in that, The reinforcement unit (6) includes a self-expanding column (61) located at the center of the main structure (1) and capable of radial expansion when exposed to water, a flexible membrane (62) radiating outward from the self-expanding column (61), a sealing strip (63) connecting the flexible membrane (62) to the side wall (11), a reinforcement grout (64) located between the side wall (11) and the self-expanding column (61), a lower connecting structure (65) that automatically opens under a set pore water pressure, and a side connecting structure (66) for the reinforcement grout to flow out. When the pore water pressure reaches the set value, the lower connecting structure opens, the self-expanding column absorbs water and expands, squeezing the flexible membrane, increasing the internal and external pressure difference of the main structure, and the reinforcement grout overflows from the side connecting structure, thus reinforcing the foundation.

8. The active prevention and control system according to claim 7, characterized in that, The lower connecting structure (65) is located at the bottom of the self-expanding column (61) and is made of unidirectional memory metal with pre-cut texture (67) on the surface. The preset deformation direction of the lower connecting structure (65) is to open inward.

9. The active prevention and control system according to claim 7, characterized in that, The side-connecting structure (66) is located on the side wall (11) and is made of unidirectional memory metal with pre-cut texture (67) on the surface. The preset deformation direction of the side-connecting structure (66) is outward opening.

10. A construction method for an active prevention and control system for sandy soil foundation failure under earthquake loading, characterized in that, Includes the following steps: S1: Site exploration, determining the location and depth of boreholes based on the actual geological survey report and construction plan, and marking the locations; S2: Bury the casing at the predetermined location, and then carry out drilling operations. The drilling depth should not exceed the casing burial depth until the predetermined burial depth is reached. S3: With the borehole as the center, the seismic frequency acquisition unit (2) is arranged in a fixed-distance ring and buried or pressed into the sandy soil layer. At the same time, the assembled main structure (1) is lowered at the borehole. S4: Sleeve the reserved optical fiber outside the seismic frequency acquisition unit (2) and reserve the connection end, pull out the borehole casing and recycle it; S5: Connect the optical fiber reserved connection end in the seismic frequency acquisition unit (2) to the DSP chip input port in the analysis feedback unit (4), and connect the power supply unit (3) to the external circuit; S6: Apply vibrations of known frequency to the far end of the site, and set up a ground motion monitoring instrument to monitor the seismic state of the reinforced sandy soil site, check the installation effect of the reinforcement device, and ensure the reliability of its operation.

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