A device for measuring the permeability characteristics of slurry in shield tunnels

Abstract

The invention discloses a measuring device for the permeability characteristics of slurry in a shield tunnel, which relates to the technical field of tunnel stability excavation, and aims to solve the existing problem that it is impossible to independently and simultaneously monitor the pressure change process and change key parameters such as the seepage coefficient, and its measurement accuracy is greatly affected by human operation and changes in disassembly and assembly time; through this measuring device, real-time monitoring and storage of experimental data on the infiltration characteristics of slurry in the shield tunnel can be achieved, and the permeability coefficient of the change in pore water pressure due to the infiltration of slurry in the shield tunnel can be analyzed based on the monitoring data of multiple sensors at different positions. The measuring device has good sealing performance, can continuously and automatically collect data, and is less affected by external interference. The measuring device can simulate different hydraulic gradient conditions through a reducer structure.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel stability excavation, in particular to a device for measuring the mud permeability characteristics of a shield tunnel. Background Art

[0002] The construction process of a slurry shield tunnel is mainly for the cutter head of the shield machine to cut the underground soil in front of the shield machine. After the cut soil is removed from the tunnel, it is hydraulically jacked in and the shield machine installs the prefabricated tunnel segments, and continues to move forward in a cycle.

[0003] During the shield excavation of slurry tunnels, the additional pressure of mud and air in the shield chamber provides support for the excavation face. The stability of the excavation face is crucial to the safety of tunnel construction. Affected by the dynamic factors of the shield method and the changes in the strata during the excavation process, such as geological conditions, mud properties, pressure application methods and penetration behavior, when the support force required for the stability of the excavation face does not match the external support force, serious accidents such as excavation face collapse and soil arching will occur, which will have a huge impact on the safety of construction workers and the economic cost of the project. Therefore, it is necessary to adopt innovative methods to study and analyze the penetration behavior of slurry support on the excavation face of shield tunnels.

[0004] At present, there are few devices for analyzing the permeability characteristics of the excavation surface of a slurry shield tunnel. The existing solution is to install pressure measuring holes on the side of a cylindrical permeability device, and sequentially monitor the pore water pressure at different positions to analyze the permeability characteristics. This method has the advantages of simple equipment and low cost, but it cannot independently and simultaneously monitor the pressure change process, and change key parameters such as the seepage coefficient, and its measurement accuracy is greatly affected by human operation and changes in disassembly and assembly time. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention discloses a measuring device for the mud permeability characteristics of a shield tunnel. The technical solution adopted is that it comprises an organic glass cylinder, the organic glass cylinder is a cylinder which is interconnected from top to bottom, and the upper and lower ends of the organic glass cylinder are respectively threadedly connected with a cylinder sealing screw cover and a cylinder spiral base, the organic glass cylinder is provided with a pressure measuring mechanism, the cylinder spiral base is provided with a gradient mechanism, and the pressure measuring mechanism and the gradient mechanism are both connected to the detection mechanism; the lower part of the organic glass cylinder is loaded with sand to simulate excavated soil, and the upper part is loaded with mud to simulate an infiltration medium, and air pressure is applied from above.

[0006] As a preferred technical solution of the present invention, the pressure measuring mechanism includes an air pressure interface, a pressure measuring hole, and an electronic pore water pressure gauge. The air pressure interface is provided on the organic glass cylinder. The air pressure interface is connected to the air pressure boosting device. The pressure measuring holes are provided in multiple groups and are staggered on the organic glass cylinder. An elastic locking mechanism is provided in the pressure measuring holes, and the elastic locking mechanism is connected to the electronic pore water pressure gauge.

[0007] As a preferred technical solution of the present invention, the pressure measuring holes 7 are grouped together, and the pressure measuring holes are arranged in two rows and staggered.

[0008] As a preferred technical solution of the present invention, the electronic pore water pressure gauge includes the No. 1 electronic pore water pressure gauge, the No. 2 electronic pore water pressure gauge, the No. 3 electronic pore water pressure gauge, the No. 4 electronic pore water pressure gauge, the No. 5 electronic pore water pressure gauge, the No. 6 electronic pore water pressure gauge, and the No. 7 electronic pore water pressure gauge, which are respectively arranged in the pressure measuring holes; the electronic pore water pressure gauge is used to measure the changes in pore water pressure at different depths during mud penetration.

[0009] As a preferred technical solution of the present invention, the gradient mechanism includes a No. 1 bin, a No. 2 bin, an overflow port, a reducer plug, and a permeable stone. The No. 2 bin is arranged on the cylindrical spiral base, and the No. 1 bin is arranged on the No. 2 bin. The diameter of the No. 1 bin is larger than that of the No. 2 bin. The No. 1 bin and the No. 2 bin are on the same axis. The No. 2 bin is provided with the overflow port connected to the outside world, the No. 1 bin is provided with a reducer plug, and the permeable stone is press-fitted between the reducer plug and the No. 2 bin; the cylindrical spiral base including the reducer plug and the permeable stone is used to change the hydraulic gradient of the measuring system.

[0010] As a preferred technical solution of the present invention, the detection mechanism includes a cable, a signal demodulator, an electronic scale and a water storage container, a rubber water hose, and a computer. The computer is connected to the signal demodulator, the electronic scale and the water storage container through the cable, the signal demodulator is connected to the electronic pore water pressure gauge through the cable, and the electronic scale and the water storage container are connected to the overflow port through the rubber water hose; the signal demodulator is used to demodulate the signal of the electronic pore water pressure gauge, the computer is used to store sensor monitoring measurement data, and the cable is used to transmit sensor signals.

[0011] The beneficial effects of the present invention are as follows: the present invention can realize real-time monitoring and storage of experimental data on the infiltration characteristics of slurry in shield tunnels through the measuring device, and can analyze the permeability coefficient based on the change of pore water pressure of slurry infiltration in shield tunnels according to the monitoring data of multiple sensors at different positions. The measuring device has good sealing performance, can continuously and automatically collect data, and is less susceptible to external interference. The measuring device can simulate different hydraulic gradient conditions through a reducer structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the specific implementation of the present invention or the technical solution in the prior art, the following will briefly introduce the drawings required for the specific implementation or the prior art description. In all the drawings, each element or part is not necessarily drawn according to the actual scale.

[0013] Figure 1 It is a schematic diagram of the structure of the present invention;

[0014] Figure 2 This is a schematic diagram of the structure of the organic glass cylinder of the present invention;

[0015] Figure 3 This is a schematic diagram of the isometric structure of the organic glass cylinder of the present invention;

[0016] Figure 4 This is a schematic diagram of the top view of the organic glass cylinder of the present invention;

[0017] Figure 5 This is a schematic diagram of the side view of the organic glass cylinder of the present invention;

[0018] Figure 6 This is a schematic diagram of the structure of the cylindrical sealing screw cover of the present invention;

[0019] Figure 7 This is a schematic diagram of the structure of the permeable stone of the present invention;

[0020] Figure 8 This is a schematic diagram of the structure of the cylindrical spiral base of the present invention;

[0021] Fig. 9 This is a schematic diagram of the top view of the cylindrical spiral base of the present invention;

[0022] Fig.10 It is a schematic diagram of the structure of the different-diameter screen tube of the present invention.

[0023] In the figure: 1. plexiglass cylinder; 2. Cylinder sealing screw cover; 3. Cylinder screw base; 301. Overflow port; 302. Reducer plug; 303. Permeable stone; 4. No. 1 electronic pore water pressure gauge; 5. No. 2 electronic pore water pressure gauge; 6. No. 3 electronic pore water pressure gauge; 7. No. 4 electronic pore water pressure gauge; 8. No. 5 electronic pore water pressure gauge; 9. No. 6 electronic pore water pressure gauge; 10. No. 7 electronic pore water pressure gauge; 11. Cable; 12. Signal demodulator; 13. Electronic scale and water storage container; 14. Rubber water pipe; 15. Computer. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0025] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] Example 1

[0027] like Figures 1 to 10 As shown, the present invention discloses a measuring device for the permeability characteristics of slurry in a shield tunnel. The technical scheme adopted is that it comprises an organic glass cylinder 1, which is made of high-strength resin plastic material and can withstand very small deformation under strong pressure. The organic glass cylinder 1 is a cylinder that is interconnected from top to bottom, and the upper and lower ends of the organic glass cylinder 1 are respectively threadedly connected with a cylinder sealing screw cover 2 and a cylinder spiral base 3, and a sealing ring is pressed between the cylinder sealing screw cover 2 and the cylinder spiral base 3 and the organic glass cylinder 1 to achieve an air pressure sealing effect. A pressure measuring mechanism is provided on the organic glass cylinder 1, and a gradient mechanism is provided on the cylinder spiral base 3. The pressure measuring mechanism and the gradient mechanism are both connected to the detection mechanism.

[0028] As a preferred technical solution of the present invention, the pressure measuring mechanism includes an air pressure interface, a pressure measuring hole, and an electronic pore water pressure gauge. The air pressure interface is provided on the organic glass cylinder 1. The air pressure interface is connected to the air pressure boosting device. The pressure measuring holes are provided in multiple groups and are staggered on the organic glass cylinder 1. An elastic locking mechanism is provided in the pressure measuring holes, and the elastic locking mechanism is connected to the electronic pore water pressure gauge.

[0029] As a preferred technical solution of the present invention, there are 7 groups of pressure measuring holes, which are arranged in two rows and staggered. The top pressure measuring hole is 310 mm away from the bottom of the plexiglass cylinder 1, and the remaining pressure measuring holes are respectively 20, 20, 20, 40, 40, and 50 mm away from top to bottom, which is convenient for the installation and practical use of the pressure measuring machine.

[0030] As a preferred technical solution of the present invention, the electronic pore water pressure gauge includes the No. 1 electronic pore water pressure gauge 4, the No. 2 electronic pore water pressure gauge 5, the No. 3 electronic pore water pressure gauge 6, the No. 4 electronic pore water pressure gauge 7, the No. 5 electronic pore water pressure gauge 8, the No. 6 electronic pore water pressure gauge 9, and the No. 7 electronic pore water pressure gauge 10, which are respectively arranged in the pressure measuring holes.

[0031] As a preferred technical solution of the present invention, the gradient mechanism includes a No. 1 bin, a No. 2 bin, an overflow port 301, a reducer plug 302, and a permeable stone 303. The No. 2 bin is arranged on the cylindrical spiral base 3, and the No. 1 bin is arranged on the No. 2 bin. The diameter of the No. 1 bin is larger than that of the No. 2 bin. The No. 1 bin and the No. 2 bin are on the same axis. The No. 2 bin is provided with the overflow port connected to the outside world. The No. 1 bin is provided with a reducer plug 302, and the reducer plug 302 is provided between the No. 2 bin and the No. 2 bin. The permeable stone 303 is pressed; it is detachably connected through a reducer plug 302, so as to achieve the purpose of changing the hydraulic gradient of seepage; a rubber ring is pressed between the reducer plug 302 and the cylindrical spiral base 3 to achieve a sealing effect; different hydraulic gradient conditions can be achieved by replacing the reducer plug 302 during the experiment, and the bottom of the reducer plug 302 contains a permeable stone 303 to prevent the sand and gravel filled in the plexiglass cylinder from flowing out; the No. 2 bin below the permeable stone 303 is a water storage cavity, and the overflow port 301 is used to collect the seepage flow.

[0032] As a preferred technical solution of the present invention, the detection mechanism includes a cable 11, a signal demodulator 12, an electronic scale and a water storage container 13, a rubber water hose 14, and a computer 15. The computer 15 is connected to the signal demodulator 12 and the electronic scale and the water storage container 13 through the cable 11; the electronic scale and the water storage container 13 collect and record the seepage flow rate; the signal demodulator 12 is connected to the electronic pore water pressure gauge through the cable 11, and the electronic scale and the water storage container 13 are connected to the overflow port 301 through the rubber water hose 14; the computer 15 reads and records data; the cable 11 connects the electronic pore water pressure gauge and the signal demodulator 12, and connects the signal demodulator 12 and the computer 15.

[0033] The working principle of the present invention is as follows: the cylinder sealing screw cover 2, the cylinder screw base 3 and the organic glass cylinder 1 are connected by threaded connection, and a rubber ring is provided at the connection to achieve an air pressure sealing effect; the air pressure hole is connected to the air pressure boosting device to provide the required air pressure inside the organic glass cylinder 1; the pressure measuring hole on the side of the organic glass cylinder 1 is connected to the No. 1 electronic pore water pressure gauge 4, the No. 2 electronic pore water pressure gauge 5, the No. 3 electronic pore water pressure gauge 6, the No. 4 electronic pore water pressure gauge 7, the No. 5 electronic pore water pressure gauge 8 through an elastic locking mechanism. Pressure gauge 8, No. 6 electronic pore water pressure gauge 9, No. 7 electronic pore water pressure gauge 10, the electronic pore water pressure gauge is sealed and connected to the organic glass cylinder 1 through the pressure measuring hole to measure the pore water pressure at the predetermined position. After the signal is collected, it is transmitted to the signal demodulator 12 by the cable 11 for analysis, and the data is read in real time and stored in the computer 14. The system drainage flows out from the overflow port on the No. 2 bin of the cylindrical spiral base 3, flows to the electronic scale and the water storage container 13 through the rubber water pipe 14, and the seepage flow of the measurement system is recorded in real time.

[0034] Measurement method: Place the sand layer in the organic glass cylinder 1, fill the shrinkage hole of the base and the part below 300mm of the organic glass cylinder 1, so that the top surface of the sand layer is between the first two groups, install mud on the top of the sand layer, seal it and connect the air pressure, the mud penetrates into the soil under the action of pressure, and the permeability characteristics of the mud in the soil can be calculated by reading the electronic pore water pressure gauge at different positions of the cylinder and observing the velocity and volume of the seeping liquid:

[0035] The permeability coefficient is solved based on the Ergun equation, and then the hydraulic gradient can be analyzed through the equivalent shrinkage principle. After confirming the pressure correspondence, the parameters obtained above can be used to give a quantitative evaluation of the permeability of mud or soil with different properties. Among them, the hydraulic gradient can be adjusted by changing the air pressure or the inner diameter of the reducer.

[0036] According to the above, the cylindrical soil body simulating the excavated soil in the experiment consists of two parts, the upper part is of length (L 1 )300mm, diameter (d 1 )80mm soil or sand column, the lower part is length (L 2 )50mm, diameter d 2 mm soil or sand column, assuming the total head difference of the system is h, the largest diameter is d 1 The head difference of the part is h 1 , small diameter d 2 The head difference of the part is h 2 , from the large diameter d 1 To the small diameter d 2 The head difference of the part is h 1-2 , then, h = h 1 +h 2 +h 1-2:

[0037] According to Darcy's law, the seepage flow rate Q of the system can be calculated according to the following formula:

[0038]

[0039] Where k is the permeability coefficient of the soil. Combining the above formula, it can be deduced:

[0040]

[0041] Assuming there is no reducer structure, the cylinder diameter is the same as the large diameter L1 pipe. If a similar seepage flow rate is required, the required pipe length Ls should meet the following formula:

[0042]

[0043] According to the above formula, the equivalent pipe diameter length that can be produced by the reducer structure of the experimental device can be calculated by the following formula:

[0044]

[0045] The experimental setup 1 =80mm,d 2 =8mm, L 1 =300mm, L 2 =50mm. According to the formula, the equivalent length of the device is 5480mm. Assuming that the air pressure applied in the laboratory is 50kPa, the equivalent hydraulic gradient of the device is i=h / L s ≈0.912. If there is no reducer structure and the pressure applied in the laboratory is 50 kPa, the equivalent hydraulic gradient of the device is i=h / (L 1 +L 2 )≈14. Compared with the previous experimental device without reducer structure, the proposed device can produce hydraulic gradient conditions similar to those in actual engineering within a limited length. In addition, the reducer plug in the base is detachable, and the hydraulic gradient conditions of the device can be adjusted by changing the inner diameter of the reducer plug.

[0046] The elastic locking mechanism involved in the present invention adopts the 304 stainless steel air pipe quick connector quick-insert pneumatic quick-connect threaded high-pressure air nozzle straight-through docking element PC4 produced by Richite, which is a product that can be purchased on the market and belongs to the prior art; the air pressure boosting device involved in the present invention adopts VjT2270 produced by VJ Tech Company of the United Kingdom, which is a product that can be purchased on the market and belongs to the prior art; the circuit connection involved in the present invention is a common means used by technical personnel in this field, and technical inspiration can be obtained through a limited number of tests, which is common knowledge.

[0047] Components not described in detail herein are prior art.

[0048] Although the specific embodiments of the present invention are described in detail above, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the purpose of the present invention, and modifications or deformations without creative labor are still within the protection scope of the present invention.

Claims

1. A device for measuring the permeability characteristics of slurry in a shield tunnel, characterized in that: The invention comprises an organic glass cylinder (1), wherein the organic glass cylinder (1) is a cylinder which is interconnected at the top and the bottom, and the upper and lower ends of the organic glass cylinder (1) are respectively threadedly connected with a cylinder sealing screw cover (2) and a cylinder screw base (3), the organic glass cylinder (1) is provided with a pressure measuring mechanism, the cylinder screw base (3) is provided with a gradient mechanism, and the pressure measuring mechanism and the gradient mechanism are both connected to a detection mechanism; the pressure measuring mechanism comprises an air pressure interface, a pressure measuring hole, and an electronic pore water pressure gauge, and the air pressure interface is provided on the organic glass cylinder (1) and is provided with an air pressure measuring hole. The air pressure interface is connected to the air pressure boosting device, the pressure measuring holes are provided in multiple groups and are staggered on the organic glass cylinder (1), the pressure measuring holes are provided with an elastic locking mechanism, and the elastic locking mechanism is connected to the electronic pore water pressure gauge; the electronic pore water pressure gauge comprises a No. 1 electronic pore water pressure gauge (4), a No. 2 electronic pore water pressure gauge (5), a No. 3 electronic pore water pressure gauge (6), a No. 4 electronic pore water pressure gauge (7), a No. 5 electronic pore water pressure gauge (8), a No. 6 electronic pore water pressure gauge (9), and a No. 7 electronic pore water pressure gauge (10), respectively. The gradient mechanism comprises a No. 1 chamber, a No. 2 chamber, an overflow port (301), a reducer plug (302), and a permeable stone (303). The No. 2 chamber is arranged on the cylindrical spiral base (3). The No. 1 chamber is arranged on the No. 2 chamber. The diameter of the No. 1 chamber is larger than that of the No. 2 chamber. The No. 1 chamber and the No. 2 chamber are on the same axis. The No. 2 chamber is provided with the overflow port (301) connected to the outside. The No. 1 chamber is provided with a reducer plug (302). The reducer plug (302) is press-fitted between the No. 2 chamber and the No. 2 chamber. The permeable stone (303) is provided; the detection mechanism comprises a cable (11), a signal demodulator (12), an electronic scale and a water storage container (13), a rubber water pipe (14), and a computer (15); the computer (15) is connected to the signal demodulator (12) and the electronic scale and the water storage container (13) through the cable (11); the signal demodulator (12) is connected to the electronic pore water pressure gauge through the cable (11); and the electronic scale and the water storage container (13) are connected to the overflow port (301) through the rubber water pipe (14).

2. A device for measuring the permeability characteristics of slurry in a shield tunnel according to claim 1, characterized in that: There are 7 groups of pressure measuring holes in total, and the pressure measuring holes are arranged in two rows and staggered.

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