A foundation pit penetration-vibration combined test device

Abstract

The utility model relates to a kind of foundation pit penetration-vibration combined test device, and it relates to the field of geotechnical engineering disaster simulation technique. Including test box main body, high-frequency vibration table, liftable water level adjusting cabin system, multi-parameter monitoring system and control box;Test box main body is installed in the high-frequency vibration table top, the liftable water level adjusting cabin system and control box are located in the side of high-frequency vibration table, and multi-parameter monitoring system one end is located in test box main body, and the other end is electrically connected with control box. The utility model solves the problem that traditional waterproof detection structure cannot simulate the coupling effect of vibration and penetration, and can quantitatively analyze the influence law of construction disturbance on soil permeability, providing theoretical support for foundation pit safety construction.

Description

Technical Field

[0001] This utility model relates to the field of geotechnical engineering disaster simulation technology, specifically a foundation pit seepage-vibration combined test device. Background Technology

[0002] Currently, the demand for research on soil permeability characteristics under dynamic loads is increasing in the field of geotechnical engineering, especially in scenarios such as foundation pit excavation and subway construction, where the coupling effect of vibration disturbance and groundwater seepage has a significant impact on engineering safety. However, traditional permeability testing devices have limitations such as limited vibration simulation range, insufficient multi-field coupling capability, and deficiencies in sealing and automation. Traditional waterproof testing structures (such as constant head permeameters) can only measure the soil permeability coefficient under static conditions, while in actual engineering, construction vibrations such as pile driving and blasting can cause damage to the soil structure, significantly altering its permeability. Against this backdrop, those skilled in the art urgently need to propose a combined permeability-vibration testing device for foundation pits. Utility Model Content

[0003] In response to the above situation and to overcome the shortcomings of existing technology, this utility model provides a foundation pit permeability-vibration combined testing device, which solves the problem that traditional waterproof testing structures cannot simulate the coupling effect of vibration and permeability. It can quantitatively analyze the influence of construction disturbance on soil permeability and provide theoretical support for safe foundation pit construction.

[0004] To achieve the above objectives, this utility model provides a combined test device for foundation pit seepage-vibration, comprising: a test chamber body, a high-frequency vibration table, a liftable water level regulating chamber system, a multi-parameter monitoring system, and a control box;

[0005] The main body of the test chamber is installed on the top of the high-frequency vibration table. The liftable water level regulating chamber system and the control box are both located on one side of the high-frequency vibration table. One end of the multi-parameter monitoring system is located on the main body of the test chamber, and the other end is electrically connected to the control box.

[0006] Furthermore, the main body of the test chamber is a double-layer 304 stainless steel welded structure with an effective internal volume of 0.96m³. 3 It has a perforated panel on top.

[0007] Furthermore, the high-frequency vibration table has a vibration frequency range of 0.1 to 20 Hz, a maximum acceleration of 5g, and waveforms including sine waves, random waves, and custom impact waveforms.

[0008] Furthermore, the liftable water level regulating chamber system includes a liftable water level regulating chamber, a ball screw, a servo motor, a mounting plate, and a guide rod; the output end of the servo motor is connected to the ball screw via a transmission connection; the ball screw passes through the mounting plate and is threadedly connected to the mounting plate; the guide rod passes through the mounting plate and is slidably connected to the mounting plate; the liftable water level regulating chamber is mounted on the mounting plate; and the liftable water level regulating chamber is connected to the water inlet of the test chamber body via a flexible waterproof hose.

[0009] Furthermore, the multi-parameter monitoring system includes a pore water pressure sensor, a triaxial vibration accelerometer, a laser displacement meter, and a data acquisition instrument. The pore water pressure sensor and the triaxial vibration accelerometer are both installed on the inner side wall of the test chamber body, and the laser displacement meter is slidably installed on the top wall inside the test chamber body. The pore water pressure sensor, the triaxial vibration accelerometer, and the laser displacement meter are all connected to the data acquisition instrument through shielded cables, and the data acquisition instrument is electrically connected to the control box.

[0010] Furthermore, the pore water pressure sensor is arranged in a three-dimensional grid with a horizontal spacing of ≤150mm and a vertical spacing of ≤100mm. The sensor probe of the pore water pressure sensor is covered with a 200-mesh filter to prevent soil particles from clogging it.

[0011] Furthermore, the laser displacement meter adopts a line laser scanning mode with a scanning frequency of ≥100Hz and a measurement range of ±50mm. The top wall inside the test chamber is equipped with a sliding rail, and the laser displacement meter slides in conjunction with the sliding rail.

[0012] The beneficial effects of this utility model are as follows:

[0013] This invention has a simple structure and is easy to operate. It can effectively solve the problem that traditional waterproof testing structures cannot simulate the coupling effect of vibration and seepage. It can quantitatively analyze the influence of construction disturbance on soil permeability and provide theoretical support for safe construction of foundation pits. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of this utility model.

[0015] In the diagram: 1-Test chamber body, 2-High frequency vibration table, 3-Liftable water level regulating chamber system, 3-1-Water level regulating chamber, 3-2-Ball screw, 3-3-Servo motor, 3-4-Water inlet, 3-5 Mounting plate, 3-6 Guide rod, 4-Multi-parameter monitoring system, 4-1-Porous water pressure sensor, 4-2-Triaxial vibration accelerometer, 4-3-Laser displacement meter, 4-4-Shielded cable, 4-5-Connection data acquisition instrument, 5-Control box. Detailed Implementation

[0016] The technical solutions in the embodiments of this utility model are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0017] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0018] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0019] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0020] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0021] like Figure 1As shown, this utility model provides a combined permeability-vibration testing device for foundation pits, comprising: a test chamber body 1, a high-frequency vibration table 2, a liftable water level regulating chamber system 3, a multi-parameter monitoring system 4, and a control box 5; the test chamber body 1 is mounted on top of the high-frequency vibration table 2, the liftable water level regulating chamber system 3 and the control box 5 are both located on one side of the high-frequency vibration table 2, one end of the multi-parameter monitoring system 4 is located on the test chamber body 1, and the other end is electrically connected to the control box 5. The high-frequency vibration table 2 and the liftable water level regulating chamber system 3 are integrally mounted on a base.

[0022] The technical solution has been further optimized. The main body 1 of the test chamber is a double-layer 304 stainless steel welded structure with an effective internal volume of 0.96m³. 3 The dimensions are 1.5m × 0.8m × 0.8m (length × width × height). The top is equipped with a perforated plate to ensure that the air pressure inside the test chamber is consistent with that in the adjustable water level control chamber system.

[0023] Further optimizing the technical solution, the high-frequency vibration table 2 has a vibration frequency range of 0.1–20 Hz, a maximum acceleration of 5g, and waveforms including sine waves, random waves, and custom impact waveforms. The high-frequency vibration table 2 is driven by an electromagnetic exciter 2-1 with a peak excitation force ≥10kN, and is equipped with an air spring vibration isolation base 2-2, achieving a vibration isolation efficiency ≥90%.

[0024] Further optimizing the technical solution, the liftable water level regulating chamber system 3 includes a liftable water level regulating chamber 3-1, a ball screw 3-2, a servo motor 3-3, a mounting plate 3-5, and a guide rod 3-6. The output end of the servo motor 3-3 is equipped with a drive wheel, and the bottom end of the ball screw 3-2 is equipped with a driven wheel. The drive wheel and the driven wheel are connected by a belt drive. The ball screw 3-2 passes through the mounting plate 3-5 and is threadedly connected to it. The guide rod 3-6 passes through the mounting plate 3-5 and is slidably connected to it. The liftable water level regulating chamber 3-1 is mounted on the mounting plate. The adjustable water level regulating chamber 3-1 is connected to the water inlet 3-4 of the main body 1 of the test chamber via a flexible waterproof hose with a pressure resistance of ≥200kPa. The interface uses a flange with a fluororubber sealing ring. The flexible hose needs to be connected to the bottom of the side wall of the main body 1 of the test chamber, avoiding the direct vibration area of ​​the high-frequency vibration table 2. Specifically, the water inlet 3-4 is opened 50mm from the bottom of the side wall of the test chamber, connected to the hose via a flange. The flange interface has an embedded rubber sealing ring with a pressure resistance of ≥200kPa. The hose is laid in an arc along the outer wall of the test chamber, with a buffer length redundancy of 10%–15% to prevent detachment due to vibration stretching. The lifting rate of the adjustable water level regulating chamber system 3 is adjustable from 0.1 to 2 m / h, with a stroke ≥1m and a water level control accuracy of ±1mm. The adjustable water level regulating chamber is controlled by a servo motor to achieve a sudden drop or rise in water level, thereby replicating the dewatering conditions of the foundation pit. Water level rise: The servo motor rotates forward, driving the liftable water level regulating chamber to rise. The water level inside the test chamber rises synchronously through the connecting pipe principle. The water head pressure is determined by the height difference of the liftable water level regulating chamber. Water level fall: The servo motor rotates in reverse, driving the liftable water level regulating chamber to fall. The water inside the test chamber flows back to the liftable water level regulating chamber through the flexible hose, simulating precipitation conditions. Dynamic water level control: The servo motor speed is adjusted in real time through a PID algorithm to match the preset water level change curve, such as a sudden drop rate of 1m / h.

[0025] To further optimize the technical solution, the multi-parameter monitoring system 4 includes a pore water pressure sensor 4-1 with a range of 0-500 kPa and an accuracy of 0.1% FS, a triaxial vibration accelerometer 4-2 with a range of ±10g and a sampling rate of 1 kHz, a laser displacement meter 4-3 with a resolution of 0.01 mm, and a data acquisition instrument 4-5. The pore water pressure sensor 4-1 and the triaxial vibration accelerometer 4-2 are both installed on the inner side wall of the test chamber body 1, and the laser displacement meter 4-3 is slidably installed on the top wall inside the test chamber body 1. The pore water pressure sensor 4-1, the triaxial vibration accelerometer 4-2, and the laser displacement meter 4-3 are all connected to the data acquisition instrument 4-5 through a shielded cable 4-4. The data acquisition instrument is electrically connected to the control box 5, thereby collecting multi-source data on infiltration, vibration, and deformation in real time. The shielded cable is laid in a 20mm deep groove along the inner wall of the test chamber to avoid direct contact with the soil. All sensors are powered by a 24VDC power supply from the data acquisition instrument, and the synchronous trigger signal is synchronized at the microsecond level through the FPGA board.

[0026] To further optimize the technical solution, the pore water pressure sensor 4-1 is arranged in a three-dimensional grid with a horizontal spacing of ≤150mm and a vertical spacing of ≤100mm. The sensor probe of the pore water pressure sensor 4-1 is covered with a 200-mesh filter to prevent soil particles from clogging it.

[0027] To further optimize the technical solution, three sets of the triaxial vibration accelerometer 4-2 can be installed on the side wall of the housing, located at the bottom, middle, and top near the vibration table, respectively, arranged along the XYZ axes. The fixing method uses a magnetic base with a vibration resistance strength ≥5g, reinforced with epoxy resin.

[0028] To further optimize the technical solution, the laser displacement gauge 4-3 adopts a line laser scanning mode with a scanning frequency ≥100Hz and a measurement range of ±50mm. A sliding rail is installed on the top wall inside the main body 1 of the test chamber, and the laser displacement gauge 4-3 slides in conjunction with the sliding rail to achieve full-section settlement monitoring. A slide rail stepper motor can be added to control the movement of the laser displacement gauge. Before displacement measurement, a reference surface calibration error ≤0.05mm is required.

[0029] In another embodiment, the controller may have a three-level safety protection mechanism: Level 1 protection: automatic frequency reduction when vibration acceleration exceeds 3g; Level 2 protection: trigger shutdown when pore water pressure gradient changes by ≥10kPa / min; Level 3 protection: activate audible and visual alarm when sealing pressure is below 0.2MPa. The data fusion analysis module incorporates a dynamic permeability coefficient calculation model.

[0030]

[0031] In the above formula, Q(t) is the seepage flow rate that varies with time, i.e., the amount of water passing through the soil sample per unit time, which is monitored in real time by the flow meter at the bottom of the test chamber, or indirectly calculated based on the volume change rate of the water level regulating chamber; A is the effective water flow area, i.e., the cross-sectional area of ​​the soil sample perpendicular to the water flow direction, determined according to the effective internal dimensions of the test chamber; Δh(t) is the head difference between the two ends of the seepage path, which changes dynamically with time. Its value is mainly taken as the ratio of the measured value P to ρg of the pore water pressure sensor 4-1 installed at the inlet 3-4, 50mm from the bottom of the test chamber side wall. L represents the effective length of the seepage path, i.e., the average path length of water flowing through the soil. Specifically, pore water pressure sensors 4-1 are deployed in a three-dimensional grid inside the soil to record the water pressure distribution at different locations. Then, the seepage field is reconstructed using an equipotential line fitting algorithm, and the average length of the streamline trajectory is calculated as its value; a vib is the vibration acceleration time history; g is the gravitational acceleration. The calculation results are displayed in real time on the human-machine interface.

[0032] This invention features a simple structure and convenient operation, enabling high-frequency vibration simulation: covering the entire frequency band from 1 to 10 Hz for pile driving and 10 to 20 Hz for blasting. Test results can directly guide construction vibration control. Specifically, it employs an electromagnetic vibrator and an air spring vibration isolation base, supporting vibration loads from 0.1 to 20 Hz, covering common construction vibration spectra. Precise water level linkage: the error between water level adjustment and vibration loading is ≤1%, reproducing changes in dynamic water pressure gradients. Specifically, a servo motor drives the water level adjustment chamber, simulating a sudden drop in water level of 0.1 to 2 meters per minute, reproducing the dewatering conditions of foundation pits. Multi-parameter synchronous acquisition: pore water pressure, vibration acceleration, and soil deformation data are recorded synchronously at a rate of 1 kHz, with an error ≤0.5%. High safety is ensured; the silicone rubber sealing ring achieves zero leakage during high-frequency vibration at 0.3 MPa pressure, guaranteeing stability during long-term testing. Engineering early warning function: when the permeability coefficient increases by more than 15%, the system automatically suggests strengthening support measures. A three-level interlocking protection mechanism prevents equipment overload and outputs a permeability coefficient decay model in real time.

[0033] The specific method of using this utility model is as follows:

[0034] First, sample preparation and sensor setup are carried out: Homogeneous silty clay (moisture content 18%, compaction degree 90%) is filled into the main body 1 of the test chamber, with a layer thickness of 100mm and each layer compacted 30 times. It should be noted that when filling cohesive soil samples, the vacuum saturation method should be used to ensure that the initial saturation degree is ≥95%; pore water pressure sensors 4-1 are set up according to a three-dimensional grid, that is, the horizontal spacing is 150mm and the vertical spacing is 100mm, with a total of 15 measuring points; triaxial vibration accelerometers 4-2 are installed on the side wall of the test chamber, with a sensitivity of 100mV / g in the XYZ directions; the top cover of the main body of the test chamber is closed, and the laser displacement meter 4-3 is installed on the moving slide rail, calibrating the laser plane to be parallel to the soil surface with an error ≤0.1°.

[0035] System water filling and initialization: First, inject sufficient water into the adjustable water level chamber through an external independent water tank. Then, raise the adjustable water level chamber 3-1 to the high position and open the solenoid valve to fill the test chamber with water through the inlet 3-3. Then, initialize the parameters through the control box: vibration waveform, ensure sine wave, frequency 2Hz, acceleration 0.5g; water level control, ensure initial water level height 0.6m, drop rate 1m / h; data sampling rate, ensure pore water pressure 100Hz, acceleration 1kHz, displacement 50Hz.

[0036] The coupled test was conducted as follows: the high-frequency vibration table 2 and the adjustable water level regulating chamber system 3 were started simultaneously, and the test lasted for 60 minutes; the seepage flow rate (measured by a graduated cylinder) was recorded every 10 minutes, and the multi-parameter data package was saved at the same time; when the laser displacement gauge detected a sudden increase in settlement (≥5mm / 10min), the secondary protection mechanism was triggered to suspend the test. If the vibration table ran continuously for more than 2 hours, it needed to be forcibly cooled for 30 minutes.

[0037] Data analysis and model building are performed: the data fusion module calculates the dynamic permeability coefficient K(t) and generates a three-dimensional surface relating K, vibration frequency, and drawdown; the permeability coefficient decay equation is fitted based on the least squares method.

[0038] K(t) = K0·e -α·arms·t

[0039] Among them, a rms The value represents the root mean square of the vibration acceleration, and α is the attenuation coefficient, determined by fitting experimental data on the attenuation of the permeability coefficient using the least squares method. The final output is a test report, including the permeability coefficient time history curve, soil damage contour map, and recommended parameters for safe construction. After the test, the sensor filter should be cleaned with compressed air to prevent soil particle compaction.

[0040] The above description is merely a preferred embodiment of the present utility model and does not constitute any limitation on the technical scope of the present utility model. Therefore, any minor modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present utility model shall still fall within the scope of the technical solution of the present utility model.

Claims

1. A combined permeability-vibration testing device for foundation pits, characterized in that, include: The test chamber body (1), high frequency vibration table (2), adjustable water level regulating chamber system (3), multi-parameter monitoring system (4) and control box (5); The test chamber body (1) is installed on the top of the high-frequency vibration table (2). The liftable water level regulating chamber system (3) and the control box (5) are both located on one side of the high-frequency vibration table (2). One end of the multi-parameter monitoring system (4) is located on the test chamber body (1), and the other end is electrically connected to the control box (5).

2. The foundation pit permeability-vibration combined testing device as described in claim 1, characterized in that, The main body (1) of the test chamber is a double-layer 304 stainless steel welded structure with an effective internal volume of 0.96m³. 3 It has a perforated panel on top.

3. The foundation pit permeability-vibration combined testing device as described in claim 1, characterized in that, The vibration frequency range of the high-frequency vibration table (2) is 0.1 to 20 Hz, the maximum acceleration is 5g, and the waveforms include sine waves, random waves and custom impact waveforms.

4. The foundation pit seepage-vibration combined testing device as described in claim 1, characterized in that, The liftable water level regulating chamber system (3) includes a liftable water level regulating chamber (3-1), a ball screw (3-2), a servo motor (3-3), a mounting plate (3-5), and a guide rod (3-6); the output end of the servo motor (3-3) is connected to the ball screw (3-2) for transmission; the ball screw (3-2) passes through the mounting plate (3-5) and is threadedly connected to the mounting plate (3-5); the guide rod (3-6) passes through the mounting plate (3-5) and is slidably connected to the mounting plate (3-5); the liftable water level regulating chamber (3-1) is mounted on the mounting plate, and the liftable water level regulating chamber (3-1) is connected to the water inlet (3-4) of the test chamber body (1) through a flexible waterproof hose.

5. The foundation pit permeability-vibration combined testing device as described in claim 2, characterized in that, The multi-parameter monitoring system (4) includes a pore water pressure sensor (4-1), a triaxial vibration accelerometer (4-2), a laser displacement meter (4-3), and a data acquisition instrument (4-5). The pore water pressure sensor (4-1) and the triaxial vibration accelerometer (4-2) are both installed on the inner side wall of the test chamber body (1). The laser displacement meter (4-3) is slidably installed on the top wall inside the test chamber body (1). The pore water pressure sensor (4-1), the triaxial vibration accelerometer (4-2), and the laser displacement meter (4-3) are all connected to the data acquisition instrument (4-5) through a shielded cable (4-4). The data acquisition instrument is electrically connected to the control box (5).

6. The foundation pit permeability-vibration combined testing device as described in claim 5, characterized in that, The pore water pressure sensor (4-1) is arranged in a three-dimensional grid with a horizontal spacing of ≤150mm and a vertical spacing of ≤100mm. The sensor probe of the pore water pressure sensor (4-1) is covered with a 200-mesh filter to prevent soil particles from clogging it.

7. The foundation pit seepage-vibration combined testing device as described in claim 5, characterized in that, The laser displacement meter (4-3) adopts a line laser scanning mode with a scanning frequency of ≥100Hz and a measurement range of ±50mm. The top wall inside the test chamber body (1) is equipped with a sliding rail, and the laser displacement meter (4-3) slides in conjunction with the sliding rail.

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