A detection device and method for vibration propagation in deep saturated soil layers

Abstract

The present invention discloses a detection device and method for vibration propagation in deep saturated soil layers. The detection device of the present invention includes a pressure chamber, a sliding rheostat system and a current measurement system. The sliding rheostat system is installed inside the pressure chamber, that is, in the inner cavity of the pressure bin. In the present invention, by placing the pressure chamber equipped with the sliding rheostat system at the position to be detected, the pore water pressure in the saturated soil layer acts on the rubber membrane through the holes on the perforated cover plate and the rigid permeable stone. When the vibration propagates to the detection point in the surrounding soil mass, the vibration will cause elastic deformation of the soil mass, resulting in an increase in the pore water pressure in the soil. Therefore, the external pressure of the pressure chamber will increase, destroying the equilibrium state. This device can realize the change of the resistance of the sliding rheostat system with the change of the pore water pressure. By observing the change of the current, the influence range of vibration propagation can be understood. Moreover, this device only needs to be buried in the deep saturated soil mass without considering the direction problem in traditional vibration measurement.

Description

Technical Field

[0001] The present invention provides a device and method for detecting vibration propagation in deep saturated soil layers, belonging to the technical fields of geotechnical engineering and tunnel engineering. Background Art

[0002] While urban underground rail transit brings convenience to people, it also generates vibrations that are transmitted to underground buildings or building foundations, posing certain potential safety hazards to adjacent buildings. Currently, existing rail transit vibration detections mainly include vibration source detection, main structure vibration detection, and surface ground vibration detection. There is less research on the detection of the propagation of rail transit vibration in underground soil, especially the lack of detection of vibration propagation in underground saturated soil. This is mainly because the water content of underground saturated soil is relatively high and the soil quality is relatively soft. This particularity makes it impossible for conventional vibration detection equipment to obtain the vibration conditions of the soil. Therefore, in order to monitor the propagation impact of vibration waves underground during the operation of underground rail transit, it is necessary to study a device and method capable of detecting vibration intensity in an environment with high water content and relatively soft soil quality.

[0003] In the deep hole vibration test in the literature "Measurement and Attenuation Analysis of Underground Deep Soil Vibration Caused by Highway Traffic", the deep hole vibration test receives velocity signals by a whole building sensor. After being amplified and integrated by an amplifier, the signals are sent to a collector for collection, and a computer is used for storage and data processing using traditional vibration sensors. This method requires using a drill to drill to the depth to be measured, then placing the deep hole vibration sensor at the bottom of the hole through a connecting rod, and adjusting the sensor direction through a rigid rod to make it consistent with the direction of the ground sensor. Finally, the rigid connecting rod is recovered. The deep hole vibration sensor measures the vibration of the soil, which requires relatively high soil strength and has poor test accuracy for saturated soft soil; during the test, the deep hole vibration sensor needs to be kept in the same direction as the ground sensor, but during vibration, the sensor is prone to displacement.

[0004] In the literature "A Deep Soil Vibration Testing Device and Its Testing Method and Process", this method fixes the vibration sensor at a fixed depth in the soil through an auxiliary device and fills it with graded sand to simulate the original undisturbed soil to the greatest extent and measure the vibration response of the deep soil. This device is actually a guiding device and has no innovation in vibration measurement. The sensor is placed at a predetermined position through a guiding rope, and the measurement direction of the sensor is affected by geological conditions and is prone to sensor displacement. Summary of the Invention

[0005] Aiming at the technical problem that the existing measurement technology cannot measure the propagation of vibration in deep saturated soil layers, the present invention proposes a detection device and method for the propagation of vibration in deep saturated soil layers, which is used to detect the propagation of urban underground rail transit vibration in deep saturated soil layers. By setting multiple measuring points on the vibration propagation path of the rail transit and determining the magnitude of the vibration intensity at the measuring points according to the variation law of the current value caused by the change of pore water pressure caused by the vibration, technicians can more intuitively and simply understand the vibration propagation range and vibration weakening law.

[0006] To achieve the purpose of the present invention, the present invention provides a device for detecting the propagation of urban underground rail transit vibration in deep saturated soil layers, including a pressure chamber, a sliding rheostat system and a current measurement system;

[0007] The pressure chamber is composed of a pressure bin, a perforated cover plate, a rigid permeable stone and a rubber membrane; the pressure bin is a hollow cylindrical shape with an open upper part and its bottom is provided with a sealable wire hole, the perforated cover plate and the rubber membrane are inverted cylindrical shapes matching the opening of the pressure bin, and the rigid permeable stone is a cylinder;

[0008] The perforated cover plate is installed at the opening of the pressure bin, and the rigid permeable stone and the rubber membrane are sequentially placed between the perforated cover plate and the pressure bin; the ratio of the outer diameter to the height of the pressure bin is between 5 and 10, and the outer diameter of the pressure bin is smaller than the inner diameter of the perforated cover plate, so that the perforated cover plate can be screwed onto the pressure bin; a plurality of through small holes are evenly distributed on the plate surface of the perforated cover plate, and the permeability coefficient of the holes is greater than the permeability coefficient of the soil layer and the permeability coefficient of the rigid permeable stone; the diameter of the rigid permeable stone is the same as the outer diameter of the pressure bin, and its permeability coefficient is greater than the permeability coefficient of the soil layer; the shape of the rubber membrane is cylindrical, and the inner diameter is the same as the outer diameter of the pressure bin, and it can be sleeved at the opening of the pressure bin;

[0009] The sliding rheostat system is installed inside the pressure chamber, that is, in the inner cavity of the pressure bin;

[0010] The sliding rheostat system is composed of a force transmission shaft, a metal slider, a metal sheet, a resistance wire, a negative connection head, a positive connection head, a guide rail support A, a guide rail support B, an insulator, a metal guide rail and a bolt;

[0011] The insulator is respectively provided with a guide rail support A and a guide rail support B at both ends, and one side of the insulator is connected to the pressure bin through the lower end of the guide rail support B by a bolt; the resistance wire is wound on the surface of the insulator, one end of the resistance wire is connected to the negative connection head, the negative connection head and the guide rail support B are on the same side, and the other end is insulated;

[0012] The metal guide rail passes through the bottom of the metal slider and is movably connected to it. The left and right ends of the metal guide rail are respectively fixed to the upper ends of the guide rail support B and the guide rail support A, and the positive connection head is connected to the metal guide rail through the upper end of the guide rail support A;

[0013] One end of the force transmission shaft is fixedly connected to the metal slider, and the other end is connected to the center point of the rubber membrane through glue. There is a metal sheet on each of the front and back sides of the metal slider. The deformation of the rubber membrane drives the displacement of the force transmission shaft, and then the metal sheet is pushed along the metal guide rail through the transmission shaft. The metal sheet contacts the resistance wire, and the deformation amount of the rubber membrane does not exceed the maximum stroke range of the metal sheet;

[0014] The current measurement system consists of a power supply, an ammeter, a protection resistor and several wires;

[0015] The positive pole of the power supply is connected to the positive pole of the ammeter through a wire, and the negative pole of the ammeter is connected to the protection resistor through a wire; the protection resistor is connected to the positive connection head through a wire passing through the wire hole, and the negative pole of the power supply is connected to the negative connection head through a wire passing through the wire hole.

[0016] The present invention also provides a detection method using the above device, and the specific steps are as follows:

[0017] (1) Install the sliding rheostat system in the pressure chamber, connect the wires to the negative connection head and the positive connection head respectively, and then connect the wires to the current measurement system. The wire length is set according to the actual depth of the pressure chamber buried. After the wire connection is completed, seal the wire hole of the pressure chamber;

[0018] (2) Move the metal slider to the end of the positive connection head of the insulator, cover the rubber membrane on the pressure chamber, and ensure that the force transmission shaft is firmly connected to the rubber membrane and the metal slider. At this time, the effective resistance length is l0;

[0019] (3) Place the rigid water-permeable stone and the perforated cover plate on the rubber membrane in turn, and require that the external liquid can only pass through the holes on the perforated cover plate and the rigid water-permeable stone, and cannot penetrate into the inside of the pressure chamber;

[0020] (4) Place the pressure chamber equipped with the sliding rheostat system at the position to be detected. The pore water pressure in the saturated soil layer acts on the rubber membrane through the holes on the perforated cover plate and the rigid water-permeable stone. The rubber membrane deforms towards the inside of the pressure chamber due to the pressure. The force transmission shaft transmits the stress and strain of the rubber membrane to the metal slider, so that the metal slider drives the metal sheet to move along the metal guide rail. When the tension of the rubber membrane and the pore water pressure are balanced, the slider stops moving, and the effective resistance length becomes l1. At this time, the current is a certain value;

[0021] (5) When the urban underground rail transit is in operation, the vibration generated by the train propagates in the surrounding soil mass. When it propagates to the detection point, according to soil mechanics knowledge, the vibration will cause elastic deformation of the soil mass, resulting in an increase in pore water pressure in the soil. Therefore, the external pressure of the pressure chamber will increase, breaking the equilibrium state. At this time, the rubber membrane will continue to deform under the action of the pore water pressure, prompting the metal slider to drive the metal sheet to displace along the metal guide rail towards the B end of the guide rail support. The effective length of the resistor changes from l1 to l2, the resistance value decreases, and the current value increases; when the vibration disappears, the elastic deformation of the soil mass recovers, the pore water pressure dissipates, the rubber membrane returns to the equilibrium state, and the current value returns to the initial state;

[0022] (6) Multiple measuring points can be set according to the actual situation to measure the vibration propagation range and vibration attenuation law.

[0023] Advantages of the present invention:

[0024] (1) This device only needs to be buried in the deep saturated soil mass, and there is no need to consider the direction problem in traditional vibration measurement;

[0025] (2) This device can realize the change of the resistance of the sliding rheostat system with the change of pore water pressure, and the influence range of vibration propagation can be understood by observing the change of current.

[0026] (3) By using the method of the present invention, the change law of pore water pressure can be reflected by the change of the current value, so as to reflect the vibration propagation situation. Description of the drawings

[0027] Figure 1 It is a schematic diagram of the device described in the present invention.

[0028] Figure 2 It is a schematic diagram of the structure of the sliding resistor described in the present invention.

[0029] Figure 3 It is a schematic diagram of the site of the device described in the present invention.

[0030] Figure 4 It is a diagram of the initial equilibrium state of the rubber membrane described in the present invention.

[0031] Figure 5 It is a diagram of the deformation of the rubber membrane under the vibration detection condition described in the present invention.

[0032] Figure 6 It is a top view of the bottom of the pressure chamber described in the present invention.

[0033] Figures 1 to 5The markings in it are as follows: 1 pressure chamber, 2 perforated cover plate, 3 rigid permeable stone, 4 rubber membrane, 5 glue, 6 force transmission shaft, 7 metal slider, 8 metal sheet, 9 resistance wire, 10 negative connection head, 11 positive connection head, 12 guide rail support A, 13 guide rail support B, 14 bolt, 15 insulator, 16 metal guide rail, 17, 19, 21, 23, 30 wire, 18 power supply, 20 ammeter, 22 protection resistor, 24 wire hole, 25 train, 26 railway track, 27 tunnel segment, 28 soil layer, 29 pressure chamber equipped with sliding rheostat system, 31 ground current measurement system. Specific implementation mode

[0034] The present invention will be further described below in conjunction with the drawings and embodiments.

[0035] As Figure 1 shown, a detection device for vibration propagation in deep saturated soil layers includes a pressure chamber, a sliding rheostat system and a current measurement system;

[0036] The pressure chamber is composed of a pressure bin 1, a perforated cover plate 2, a rigid permeable stone 3 and a rubber membrane 4; the pressure bin 1 is a hollow cylindrical shape with an open upper part and its bottom is provided with a sealable wire hole 24, the perforated cover plate 2 and the rubber membrane 4 are inverted cylindrical shapes matching the opening of the pressure bin, and the rigid permeable stone 3 is a cylinder;

[0037] The perforated cover plate 2 is installed at the opening of the pressure bin 1, and the rigid permeable stone 2 and the rubber membrane 4 are sequentially placed between the perforated cover plate 2 and the pressure bin 1; the ratio of the outer diameter to the height of the pressure bin 1 is between 5 and 10, and the outer diameter of the pressure bin is smaller than the inner diameter of the perforated cover plate, so that the perforated cover plate can be screwed onto the pressure bin; a plurality of through small holes are evenly distributed on the plate surface of the perforated cover plate 2, and the permeability coefficient of the holes is greater than the permeability coefficient of the soil layer and the permeability coefficient of the rigid permeable stone; the diameter of the rigid permeable stone 3 is the same as the outer diameter of the pressure bin, and its permeability coefficient is greater than the permeability coefficient of the soil layer; the shape of the rubber membrane 4 is cylindrical, and the inner diameter is the same as the outer diameter of the pressure bin, and it can be sleeved at the opening of the pressure bin;

[0038] The sliding rheostat system is installed inside the pressure chamber, that is, in the inner cavity of the pressure bin 1;

[0039] The sliding rheostat system is composed of a force transmission shaft 6, a metal slider 7, a metal sheet 8, a resistance wire 9, a negative connection head 10, a positive connection head 11, a guide rail support A 12, a guide rail support B 13, an insulator 15, a metal guide rail 16 and a bolt 14;

[0040] The insulator 15 is provided with a guide rail support A12 and a guide rail support B13 at both ends respectively. One side of the insulator 15 is connected to the pressure chamber 1 through the lower end of the guide rail support B13 by a bolt 14. The resistance wire 9 is wound on the surface of the insulator 15. One end of the resistance wire 9 is connected to the negative connection head 10. The negative connection head 10 is on the same side as the guide rail support B13, and the other end is insulated.

[0041] The metal guide rail 16 passes through the bottom of the metal slider 7 and is movably connected to it. The left and right ends of the metal guide rail 16 are respectively fixedly connected to the upper ends of the guide rail support B13 and the guide rail support A12. And the positive connection head 11 is connected to the metal guide rail 16 through the upper end of the guide rail support A12.

[0042] One end of the force transmission shaft 6 is fixedly connected to the metal slider 7, and the other end is connected to the center point of the rubber membrane 4 by glue. A metal sheet 8 is provided on each of the front and rear sides of the metal slider 7. The deformation of the rubber membrane drives the displacement of the force transmission shaft, and then the metal sheet is pushed along the metal guide rail through the transmission shaft. The metal sheet contacts the resistance wire, and the deformation amount of the rubber membrane does not exceed the maximum stroke range of the metal sheet.

[0043] The current measurement system is composed of a power supply 18, an ammeter 20, a protection resistor 22 and several wires.

[0044] The positive pole of the power supply is connected to the positive pole of the ammeter 20 through a wire 19. The negative pole of the ammeter 20 is connected to the protection resistor 22 through a wire 21. The protection resistor 22 is connected to the positive connection head 11 through a wire 23 passing through the wire hole 24. The negative pole of the power supply 18 is connected to the negative connection head 10 through a wire 17 passing through the wire hole 24.

[0045] A detection method for vibration propagation in deep saturated soil layers, as Figure 1 shown, the operation steps are as follows:

[0046] (1) Install the sliding rheostat system in the pressure chamber, connect the wire to the negative connection head, connect the wire to the positive connection head, and then connect the wire and the wire to the current measurement system. The length of the wire is set according to the actual depth of the pressure chamber buried. After the wire connection is completed, seal the sealing hole.

[0047] (2) Move the metal slider to the front end of the insulator, cover the rubber membrane on the pressure chamber, and ensure that the force transmission shaft is firmly connected to the rubber membrane and the metal slider. At this time, the effective resistance length is l0.

[0048] (3) Cover the rigid permeable stone and the perforated cover plate on the pressure chamber, and require that the external liquid can only pass through the holes on the perforated cover plate and the rigid permeable stone and cannot penetrate into the interior of the pressure chamber.

[0049] (4) Place multiple pressure chambers equipped with the sliding rheostat system at the positions to be detected, asFigure 3 , the pore water pressure in the saturated soil layer acts on the rubber membrane through the holes in the perforated cover plate and the rigid permeable stone. Due to the pressure, the rubber membrane deforms towards the inside of the pressure chamber. The force transmission shaft transmits the stress and strain of the rubber membrane to the metal slider, causing the metal slider to drive the metal sheet to move along the metal guide rail. When the tension of the rubber membrane and the pore water pressure are balanced, the slider stops moving, and the effective resistance length becomes l1. At this time, the current is a certain value, such as Figure 4 shown;

[0050] (5) According to soil mechanics knowledge, vibration can cause elastic deformation of saturated soil, thereby squeezing and flowing the pore water in the soil, resulting in the change of pore water pressure with the intensity of the vibration wave. Therefore, when the urban underground rail transit operates, the vibration generated by the train propagates in the surrounding soil. When it propagates to the detection point, the external pressure of the pressure chamber will increase, destroying the equilibrium state. At this time, the rubber membrane will continue to deform under the action of the pore water pressure, prompting the metal slider to drive the metal sheet to displace towards the end of the metal guide rail, and the effective resistance length changes from l1 to l2, as Figure 5 shown. At this time, the resistance value decreases and the current value increases. When the vibration disappears, the elastic deformation of the soil recovers, the pore water pressure dissipates, and the rubber membrane returns to the equilibrium state, and the current value becomes the initial state;

[0051] (6) Multiple measuring points can be set according to the actual situation to measure the vibration propagation range and the vibration attenuation law.

Claims

1. A detection device for vibration propagation in deep saturated soil layers, characterized in that, It includes a pressure chamber, a sliding resistor system and a current measurement system; The pressure chamber is composed of a pressure bin (1), a perforated cover plate (2), a rigid permeable stone (3) and a rubber membrane (4); The pressure bin (1) is a hollow cylindrical shape with an open upper part and has a sealable wire hole (24) at its bottom. The perforated cover plate (2) and the rubber membrane (4) are in an inverted cylindrical shape matching the opening of the pressure bin (1). The rigid permeable stone (3) is a cylinder. The perforated cover plate (2) is installed at the opening of the pressure bin (1), and the rigid permeable stone (3) and the rubber membrane (4) are successively placed between the perforated cover plate (2) and the pressure bin (1); The sliding resistor system is installed inside the pressure chamber, that is, in the inner cavity of the pressure bin (1). The sliding resistor system is composed of a force transmission shaft (6), a metal slider (7), a metal sheet (8), a resistance wire (9), a negative connection head (10), a positive connection head (11), a guide rail support A (12), a guide rail support B (13), an insulator (15), a metal guide rail (16) and a bolt (14); Both ends of the insulator (15) are respectively provided with a guide rail support A (12) and a guide rail support B (13). One side of this insulator (15) is connected to the pressure bin (1) through the lower end of the guide rail support B (13) by a bolt (14). The resistance wire (9) is wound on the surface of the insulator (15). One end of the resistance wire (9) is connected to the negative connection head (10), and the negative connection head (10) and the guide rail support B (13) are on the same side. The other end is insulated; The metal guide rail (16) passes through the bottom of the metal slider (7) and is movably connected to it. The left and right ends of the metal guide rail (16) are respectively fixedly connected to the upper ends of the guide rail support B (13) and the guide rail support A (12), and the positive connection head (11) is connected to the metal guide rail (16) through the upper end of the guide rail support A (12); One end of the force transmission shaft (6) is fixedly connected to the metal slider (7), and the other end is connected to the center point of the rubber membrane (4) by glue. There is a metal sheet (8) on each of the front and back sides of the metal slider (7); The current measurement system is composed of a power supply (18), an ammeter (20), a protection resistor (22) and several wires; The positive pole of the power supply is connected to the positive pole of the ammeter (20) through a wire (19). The negative pole of the ammeter (20) is connected to the protection resistor (22) through a wire (21). The protection resistor (22) is connected to the positive connection head (11) through a wire (23) passing through the wire hole (24). The negative pole of the power supply (18) is connected to the negative connection head (10) through a wire (17) passing through the wire hole (24).

2. The detection device for vibration propagation in deep saturated soil layers according to claim 1, wherein The outer diameter of the pressure bin (1) is smaller than the inner diameter of the perforated cover plate (2), so that the perforated cover plate (2) can be screwed onto the pressure bin (1). The ratio of the outer diameter to the height of the pressure bin (1) is between 5 and 10.

3. The detection device for vibration propagation in deep saturated soil layers according to claim 2, characterized in that, The plate surface of the perforated cover plate (2) is evenly distributed with a plurality of through small holes, and the permeability coefficient of the holes is greater than the permeability coefficient of the soil layer and the permeability coefficient of the rigid permeable stone (3); The diameter of the rigid permeable stone (3) is the same as the outer diameter of the pressure bin (1), and its permeability coefficient is greater than the permeability coefficient of the soil layer; The rubber membrane (4) is in the shape of a cylindrical barrel, with an inner diameter equal to the outer diameter of the pressure chamber (1), and can be sleeved at the opening of the pressure chamber (1).

4. The detection device for vibration propagation in deep saturated soil layers according to claim 1, wherein, The metal sheet is in contact with the resistance wire.

5. A detection method using the device according to any one of claims 1 to 4, characterized in that, The specific steps are as follows: (1) Install the sliding rheostat system in the pressure chamber, connect the wires to the negative connection head and the positive connection head respectively, then connect the wires to the current measurement system, and seal the wire hole of the pressure chamber after the wire connection is completed; (2) Move the metal slider to the positive connection head end of the insulator, cover the rubber membrane on the pressure chamber, and ensure that the force transmission shaft is firmly connected to the rubber membrane and the metal slider. At this time, the effective resistance length is l0; (3) Place the rigid water-permeable stone and the perforated cover plate on the rubber membrane in sequence, requiring that the external liquid can only pass through the holes in the perforated cover plate and the rigid water-permeable stone, and cannot penetrate into the interior of the pressure chamber; (4) Place the pressure chamber equipped with the sliding rheostat system at the position to be detected. The pore water pressure in the saturated soil layer acts on the rubber membrane through the holes in the perforated cover plate and the rigid water-permeable stone. Due to the pressure, the rubber membrane deforms towards the interior of the pressure chamber. The force transmission shaft transmits the stress and strain of the rubber membrane to the metal slider, causing the metal slider to drive the metal sheet to move along the metal guide rail. When the tension of the rubber membrane and the pore water pressure are balanced, the slider stops moving, and the effective resistance length becomes l1. At this time, the current is a certain value; (5) When the urban underground rail transit is operating, the vibration generated by the train propagates in the surrounding soil mass. When it propagates to the detection point, according to soil mechanics knowledge, the vibration will cause elastic deformation of the soil mass, resulting in an increase in the pore water pressure in the soil. Therefore, the external pressure of the pressure chamber will increase, destroying the equilibrium state. At this time, the rubber membrane will continue to deform under the action of the pore water pressure, prompting the metal slider to drive the metal sheet to displace along the metal guide rail towards the B end of the guide rail support. The effective resistance length changes from l1 to l2, the resistance value decreases, and the current value increases; when the vibration disappears, the elastic deformation of the soil mass recovers, the pore water pressure dissipates, and the rubber membrane returns to the equilibrium state, and the current value becomes the initial state; (6) Multiple measuring points can be set according to the actual situation to measure the vibration propagation range and the vibration attenuation law.

6. The detection method according to claim 5, wherein The length of the wire described in step (1) is set according to the actual situation of the buried depth of the pressure chamber.

7. The detection method according to claim 5, characterized in that In step (4), the deformation of the rubber membrane drives the displacement of the force transmission shaft, and then pushes the metal sheet to move along the metal guide rail through the transmission shaft. The deformation amount of the rubber membrane does not exceed the maximum stroke range of the metal sheet.

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