CN211623436U - Gas injection system for preventing liquefaction from leading to floating of tunnel segment - Google Patents

Abstract

The utility model discloses a gas injection system for preventing the floating of tunnel segments caused by liquefaction, comprising a monitoring system, a gas injection system and a control system; the monitoring system comprises a pore water pressure sensor, a first displacement sensor and a data acquisition instrument; the pore water pressure The sensor is used to measure the seepage water pressure inside the soil body, and it is installed in the tunnel soil body; the first displacement sensor is installed between the outer surface of the segment and the outer soil body; the pore water pressure sensor and the first displacement sensor are wired or wireless. It is connected with the data acquisition instrument; the gas injection system includes a gas pump, a pressure regulating valve and a gas pipe connected in sequence; the gas pipe is used to transport gas to the liquefied soil body; the control system receives the signal from the monitoring system, and outputs the signal to control the work of the gas injection system. The utility model can start the gas injection system to inject gas to the liquefied soil body, thereby reducing the liquefaction degree of the soil body.

Description

A gas injection system to prevent liquefaction from causing tunnel segments to float up

technical field

The utility model relates to the field of shield tunnels, in particular to a gas injection system for preventing liquefaction from causing tunnel segments to float up.

Background technique

At present, urban subway tunnels are generally constructed by shield method, but as the strata encountered in the process of shield construction become more and more complex, higher requirements for shield construction technology are put forward. In the process of subway shield tunneling construction, the problem of segment floating is relatively prominent, and some projects are even serious enough to set up slope adjustment to suit the line design, resulting in relatively large construction period and economic losses. In order to ensure that the subway tunnel line type meets the design and guarantees the quality of the project, it is necessary to control the floating displacement on the segment within the specified reasonable range. The floating of the segment during shield tunneling is mainly caused by the insufficient anti-floating ability of the segment. The floating problem of the segment is affected by a variety of complex factors, including hydrogeology, engineering geology, tunneling methods and technological measures, segment structure, pipe Post-pressing, etc. If the floating value of the segment is large, if it is not controlled, it will easily lead to problems such as segment misplacement, cracking, damage and deviation of the tunnel axis, thus affecting the tunnel forming quality.

At present, the domestic methods of dealing with the floating of segments include changing the grouting consistency and two-liquid vertical synchronous grouting. The adhesion between the tunnel and the tunnel can resist the floating of the tunnel segment. When this method is constructed in a stratum with abundant water in the stratum, it is difficult to implement the method because the groundwater carries the slurry and easily flows to the sealed soil tank. . Moreover, in the construction process of controlling the floating of the segment by simply grouting, it may also cause the overall floating of the tunnel or the partial misalignment of the segment when the grouting pressure is too large.

SUMMARY OF THE INVENTION

In order to solve the technical problems existing in the known technology, the utility model provides a gas injection system for preventing the floating of tunnel segments caused by liquefaction by adopting a comprehensive method.

The technical scheme adopted by the utility model to solve the technical problems existing in the known technology is: a gas injection system for preventing liquefaction from causing tunnel segments to float up, including a monitoring system, a gas injection system and a control system; the monitoring system includes a pore A water pressure sensor, a first displacement sensor and a data acquisition instrument; the pore water pressure sensor is used to measure the seepage water pressure inside the soil body, and is arranged in the soil body at different positions of the tunnel; the first displacement sensor is used to detect The relative displacement between the tunnel segment and the soil outside the segment is set between the outer surface of the tunnel segment and the soil outside the segment; the pore water pressure sensor and the first displacement sensor communicate with the The gas injection system includes an air pump, a pressure regulating valve and a gas pipe connected in sequence; the gas pump is used to generate compressed gas; the pressure regulating valve is used to adjust the pressure of the compressed gas; the gas pipe is used for The compressed gas is delivered to the liquefied soil body; the control system receives the signal from the monitoring system, and outputs the signal to control the operation of the gas injection system.

Further, eight pore water pressure sensors are evenly distributed around the circumference of the tunnel.

Further, the first displacement sensor is a rebound type LVDT displacement sensor.

Further, the pressure regulating valve is an electric pressure regulating valve; the output signal of the control system controls the operation of the electric pressure regulating valve.

Further, the trachea includes a dry trachea and a bronchi; a row of ventilation holes with a diameter of 1.5-2.5 mm is arranged on the bronchi; the bronchi extends into the liquefied soil.

Further, the dry trachea and the bronchi are made of polypropylene.

Further, the monitoring system further includes a second displacement sensor; the second displacement sensor is used to detect the relative displacement between the tunnel segments; the second displacement sensor is arranged on the opposite end faces of the two connected tunnel segments time; the second displacement sensor is connected with the data acquisition instrument in a wired or wireless manner.

Further, the second displacement sensor is a rebound type LVDT displacement sensor.

Further, 8 of the second displacement sensors are evenly distributed along the circumferential direction of the tunnel segment.

The advantages and positive effects of the utility model are as follows: the utility model embeds a plurality of pore water pressure sensors in the soil at different positions of the tunnel; between the outer surface of the tunnel segment and the soil outside the segment, pre-embedded for detection The first displacement sensor for the relative displacement between the tunnel segment and the soil outside the segment, etc.; the measurement sensors such as the pore water pressure sensor and the first displacement sensor are connected to the data acquisition instrument through wired or wireless means; online real-time by the data acquisition instrument Collect the seepage water pressure inside the soil at different positions of the tunnel and the relative displacement between the tunnel segment and the soil outside the segment. It can provide online real-time and historical data of the seepage water pressure inside the soil mass and the relative displacement between the tunnel segment and the soil outside the segment during the construction and use of the tunnel. It can quickly detect when the soil liquefaction causes the tunnel segment to float up, and transmit the data to the control system and tunnel safety monitoring personnel in time through the data acquisition instrument.

The utility model can monitor the pore water pressure and the floating situation of the tunnel segment in real time. If the pore water pressure is too large and causes the tunnel segment to float, the control system can send a signal to start the gas injection system to inject gas into the liquefied soil, so as to reduce the amount of soil. The pore water pressure can reduce the liquefaction degree of the soil, realize the anti-floating design of the tunnel, and ensure the safety and stability of the structure.

Description of drawings

Fig. 1 is a structural schematic diagram of the present utility model.

In the figure: 1. Pore water pressure sensor; 2. Second displacement sensor; 3. Signal line; 4. Data acquisition instrument; 5. Control system; 6. Air pump; 7. Pressure regulating valve; 8. Air pipe; 9. Soil body; 10, segment.

Detailed ways

In order to further understand the content of the invention, features and effects of the present utility model, the following embodiments are listed herewith, and are described in detail as follows in conjunction with the accompanying drawings:

Please refer to FIG. 1 , a gas injection system for preventing liquefaction from causing tunnel segments to float up, including a monitoring system, a gas injection system and a control system 5; the monitoring system includes a pore water pressure sensor 1, a first displacement sensor and a data acquisition instrument 4. The pore water pressure sensor 1 is used to measure the seepage water pressure inside the soil body 9, and it is installed in the soil body 9 at different positions of the tunnel; the first displacement sensor is used to detect the tunnel segment 10 and the outside of the segment. The relative displacement between the soil bodies 9 is set between the outer surface of the tunnel segment 10 and the soil body 9 outside the segment; the pore water pressure sensor 1 and the first displacement sensor are connected with the data through wired or wireless means The gas injection system includes a gas pump 6, a pressure regulating valve 7 and a gas pipe 8 connected in sequence; the gas pump 6 is used to generate compressed gas; the pressure regulating valve 7 is used to adjust the pressure of the compressed gas; the The gas pipe 8 is used to deliver compressed gas to the liquefied soil body 9; the control system 5 receives the signal from the monitoring system, and outputs the signal to control the operation of the gas injection system.

The displacement sensor generally includes a fixed part and a movable moving part, and the reading of the displacement sensor changes linearly with the relative displacement distance of the fixed part and the moving part. The fixed part of the displacement sensor can be installed on one of the two objects that are displaced from each other; the moving part can be fixed on the other object; The relative displacement with the fixed part is detected by the displacement sensor; the displacement between the moving part and the fixed part is the mutual displacement between the two objects. The movable moving part may also be a matching device that is placed on the target object to cooperate with the fixed part to generate a displacement signal when the displacement sensor detects the displacement of the target object.

The fixing part of the first displacement sensor can be arranged in the soil body 9 outside the segment, for example, it can be installed on a rigid support ring embedded in the soil body. The fixing part of the first displacement sensor can also be arranged in the tunnel segment 10 .

In the case where the fixed part of the first displacement sensor can be arranged in the outer soil body 9 of the segment, if the first displacement sensor is a separate displacement sensor, the separate displacement sensor includes a fixed part and a fixed part that moves relatively to the fixed part. The movable part can be arranged on the outer surface of the segment 10 with the movable part of the first displacement sensor; the relative displacement between the fixed part and the movable part detected by the first displacement sensor is the tunnel segment 10 and the soil outside the segment The relative displacement between 9. If the first displacement sensor is a spring-type integrated displacement sensor, its telescopic displacement detection head is in contact with the outer surface of the segment 10 . The displacement change of the expansion and contraction of the displacement detection head is the relative displacement between the tunnel segment 10 and the soil body 9 outside the segment.

For the case where the fixed portion of the first displacement sensor is disposed in the tunnel segment 10, reference may be made to the above-mentioned installation method and working principle.

The pore water pressure sensor 1 and the first displacement sensor are used to detect the pore water pressure of the soil body 9 at the tunnel structure, the relative displacement between the tunnel segment 10 and the soil body 9 outside the segment, etc., so that the tunnel segment 10 is caused by liquefaction. When floating, it can be quickly detected, and the data can be immediately transmitted to the control system 5 and tunnel safety monitoring personnel through the data acquisition device 4 . Using the gas injection system to inject gas into 9 places of the liquefied soil body can reduce the pore water pressure of the tunnel soil body 9, reduce the liquefaction degree of the soil body 9, realize the anti-floating design of the tunnel, and ensure the safety and stability of the structure.

In order to detect the penetrating water pressure of the soil body 9 at different positions of the tunnel and make the measurement data more accurate, 8 pore water pressure sensors 1 can be evenly distributed around the circumference of the tunnel.

When the pore water pressure sensor 1 and the first displacement sensor send detection signals wirelessly, they are connected to the data acquisition instrument 4 wirelessly; the wireless connection reduces a lot of wiring.

The detection direction of the first displacement sensor can be perpendicular to the horizontal plane, or along the radial direction of the tunnel segment 10. The first displacement sensor is arranged to detect the floating or subsidence of the tunnel segment 10 relative to the soil body 9 outside the segment, and the tunnel segment. The sheet 10 is laterally displaced relative to the outer soil body 9 of the segment, etc.

A plurality of first displacement sensors whose detection directions are perpendicular to the horizontal plane can be evenly distributed along the tunnel axis, with a uniform spacing of 1 to 10 meters. It is convenient to obtain the floating or subsidence of the tunnel segment 10 relative to the soil body 9 outside the segment at multiple positions along the axial direction of the tunnel segment 10 .

The first displacement sensor may be a capacitive displacement sensor or an inductive displacement sensor. These two displacement sensors are simple in structure and can measure tiny displacements.

The first displacement sensor may be a resilient LVDT displacement sensor. This displacement sensor is easy to install.

The gas injection system includes devices such as a gas pump 6, a pressure regulating valve 7 and a gas pipe 8 that are connected in sequence; the gas pump 6 generates compressed gas to the pressure regulating valve 7; the pressure regulating valve 7 adjusts the pressure of the compressed gas, and after adjustment The compressed gas is transported by the gas pipe 8 to the liquefied soil body 9; the pressure regulating valve 7 can be an electric pressure regulating valve; according to the detection result of the pore water pressure sensor 1, the control system 5 outputs a signal to control the The work of the electric pressure regulating valve automatically controls the gas injection pressure.

The trachea 8 may include dry trachea and bronchi; a row of ventilation holes with a diameter of 1.5-2.5 mm may be provided on the bronchi; the bronchi extends into the liquefied soil body 9 . The bronchus is provided with a row of ventilation holes with a diameter of 1.5 to 2.5 mm, which is convenient for evenly injecting gas into the liquefied soil body 9 .

The dry trachea and the bronchi can be made of polypropylene. Polypropylene material has high impact resistance, strong and tough mechanical properties, and is resistant to various organic solvents and acid and alkali corrosion.

Further, the monitoring system may further include a second displacement sensor 2; the second displacement sensor 2 may be used to detect the relative displacement between the tunnel segments 10; the second displacement sensor 2 may be provided in two adjacent Between the opposite end faces of the tunnel segment 10; the second displacement sensor 2 can be connected to the data acquisition instrument 4 in a wired or wireless manner.

The fixed part of the second displacement sensor 2 can be arranged on the opposite end faces of the two connected tunnel segments 10; if the second displacement sensor 2 is a separate displacement sensor, the separate displacement sensor includes a fixed part and a separate displacement sensor. The movable part of the fixed part moves relatively, the fixed part and the movable part of the second displacement sensor 2 of the separate body can be respectively set on the opposite end faces of the two connected tunnel segments 10; the fixed part detected by the second displacement sensor 2 The relative displacement between the moving part and the moving part is the relative displacement between the two connected tunnel segments 10 . If the second displacement sensor 2 is a rebound-type integrated displacement sensor, the fixing part of the second displacement sensor 2 can be arranged on one of the end faces of the two adjacent tunnel segments 10, so that the telescopic displacement detection head can be connected to the The end faces of the other tunnel segment 10 are in contact. The displacement change of the expansion and contraction of the displacement detection head is the relative displacement between the two connected tunnel segments 10 .

The transmission mode of the detection signal of the second displacement sensor 2 can be selected in a wired or wireless manner; the second displacement sensor 2 can be connected with the data acquisition instrument 4 in a wired or wireless manner. The wireless approach reduces a lot of wiring.

The detection direction of the second displacement sensor 2 can be parallel or perpendicular to the axis of the tunnel segment 10 , and the second displacement sensor 2 is provided to detect relative axial and radial displacements between the tunnel segments 10 .

Eight second displacement sensors 2 whose detection directions are parallel to the horizontal plane may be uniformly distributed in the circumferential direction on the opposite end faces of the two connected tunnel segments 10 . It is convenient to accurately measure the variation of the gap in the horizontal direction at each position of the opposite end faces of the two connected tunnel segments 10 .

The second displacement sensor 2 can be a capacitive displacement sensor or an inductive displacement sensor. These two displacement sensors are simple in structure and can measure tiny displacements.

The second displacement sensor 2 may be a rebound LVDT displacement sensor. This displacement sensor is easy to install.

The control system 5 can adopt control systems such as industrial computer, programmable controller, single-chip microcomputer; control systems such as industrial computer, programmable controller, single-chip microcomputer, and pore water pressure sensor 1, first displacement sensor, second displacement sensor 2, data The acquisition instrument 4, the air pump 6, the pressure regulating valve 7, the electric pressure regulating valve and other devices can all adopt the applicable products in the prior art. Control systems such as industrial computers, programmable controllers, and single-chip microcomputers can use methods in the prior art to control devices such as the air pump 6 , the pressure regulating valve 7 , and the air pipe 8 .

The present invention also provides an embodiment of a gas injection method of a gas injection system for preventing liquefaction from causing the tunnel segment to float up. The method adopts the above-mentioned gas injection system for preventing the liquefaction from causing the tunnel segment to float up, including the following steps:

Step 1, install and fix the first displacement sensor;

Step 2, carry out the structural assembly of the tunnel segment 10;

Step 3, bury the pore water pressure sensor 1 in the soil body 9 through the secondary grouting hole in the segment 10;

Step 4, connect the first displacement sensor and the pore water pressure sensor 1 with the data acquisition instrument 4;

Step 5, the data acquisition instrument 4 collects and processes the signal, and sends the processed signal to the control system 5;

In step 6, the control system 5 further processes and analyzes the signals collected by the data acquisition instrument 4; it compares the monitoring result with the set critical value; when the monitoring result exceeds the set critical value, it sends a signal to start the gas injection system.

A plurality of first displacement sensors whose detection directions are perpendicular to the horizontal plane can be evenly distributed along the tunnel axis, with a uniform spacing of 1 to 10 meters. The first displacement sensor is used to detect the floating or subsidence of the tunnel segment 10, and the detection provides the change of the soil body 9 outside the segment, and also indirectly reflects the change of the seepage water pressure.

Below in conjunction with a preferred embodiment of the present utility model, the working principle and work flow of the present utility model will be described:

A gas injection system for preventing tunnel segments from floating up due to liquefaction, comprising a monitoring system, a gas injection system and a control system 5; the monitoring system comprises a pore water pressure sensor 1, a first displacement sensor and a data acquisition instrument 4; the pore The water pressure sensor 1 is used to measure the seepage water pressure inside the soil body 9, and it is arranged in the soil body 9 at different positions of the tunnel; the first displacement sensor is used to detect the pressure between the tunnel segment 10 and the soil body 9 outside the segment. The relative displacement is set between the outer surface of the tunnel segment 10 and the outer soil body 9 of the segment; the data acquisition instrument 4 is used to collect the signals of the pore water pressure sensor 1 and the first displacement sensor; the pore The water pressure sensor 1 and the first displacement sensor are connected to the data acquisition instrument 4 by wire; the gas injection system includes an air pump 6, a pressure regulating valve 7 and an air pipe 8 connected in sequence; the air pump 6 is used to generate Compressed gas; the pressure regulating valve 7 is used to adjust the pressure of the compressed gas; the gas pipe 8 is used to deliver the compressed gas to the liquefied soil 9; the control system 5 receives the signal from the monitoring system, and outputs the signal control The gas injection system works.

The pressure regulating valve 7 is an electric pressure regulating valve, and the trachea 8 includes a dry trachea and a bronchi; a row of ventilation holes with a diameter of 1.5-2.5 mm is arranged on the bronchi; The dry trachea and the bronchi are made of polypropylene.

Pore water pressure sensor 1 can use PX409-2.5GV pressure sensor produced by American OMEGA company, the first displacement sensor and second displacement sensor 2 can use pen-shaped rebound LVDT displacement sensor produced by American OMEGA company, data acquisition instrument 4 The DP41-8 data acquisition instrument 4 produced by the American OMEGA company can be used.

The control system 5 can be an industrial personal computer. An industrial personal computer (IPC) is an industrial control computer, which is a general term for tools that use a bus structure to detect and control the production process, electromechanical equipment, and process equipment. IPCs have important computer attributes and features, such as computer motherboards, CPUs, hard disks, memory, peripherals and interfaces, as well as operating systems, control networks and protocols, computing power, and friendly man-machine interface.

Eight pore water pressure sensors 1 are pre-embedded in the tunnel soil 9, and a pore water pressure sensor 1 is installed at intervals of 45° from the tunnel vault. By detecting the water content of the soil body 9, the gas injection system is activated immediately, and the liquefaction of the soil body 9 is prevented by injecting air, thereby reducing the harm caused by the floating of the tunnel.

The gas injection system of the present invention, which prevents liquefaction from causing the tunnel segment to float up, can monitor the pore water pressure in real time. If the pore water pressure is too large, the gas injection system can be activated to reduce the pore water pressure of the soil body 9 and reduce the soil pore water pressure. The liquefaction degree of the body 9 is realized, the anti-floating design of the tunnel is realized, and the safety and stability of the structure are ensured.

A preferred gas injection method for preventing the liquefaction from causing the floating of the tunnel segment is as follows:

Step 1, the first displacement sensor is pre-buried in the reinforcement cage of the tunnel segment structure, and after fixing, concrete is poured;

Step 2, assembling the tunnel segment structure;

Step 3, bury the pore water pressure sensor 1 in the soil body 9 through the secondary grouting hole in the segment 10; set up a pore water pressure sensor 1 every 45° from the tunnel vault;

Step 4, connect the pore water pressure sensor 1 and the first displacement sensor to the data acquisition instrument 4;

Step 5, assemble the gas injection system, and extend the gas pipe 8 of the gas injection system into the soil body 9 that is prone to liquefaction;

Step 5, connect the industrial computer, the connection acquisition instrument, the air pump 6 and the electric pressure regulating valve;

Step 5, the data acquisition instrument 4 collects the detection result data of the pore water pressure sensor 1 and the first displacement sensor, and performs preliminary processing, including A/D conversion, data calibration, etc.; the data acquisition instrument 4 sends the processed signal to the industrial computer ; The industrial computer further processes and analyzes the input signal; it compares the monitoring result with the set critical value; when the monitoring result exceeds the set critical value; it sends a signal to start the gas injection system.

The industrial computer further processes and analyzes the input signal, and can analyze the degree of liquefaction of the soil 9 around the tunnel caused by the magnitude of the earthquake; it also displays, stores and sends the analyzed data to other data analysis platforms.

The set critical value can refer to the following standards: when the monitoring value of the pore water pressure of the data acquisition instrument 4 subtracts the initial pore water pressure, and then the ratio to the initial effective stress is close to 1, the soil body 9 is considered to be liquefied.

The above-mentioned embodiments are only used to illustrate the technical idea and characteristics of the present invention, and the purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly, and the present invention cannot be limited only by the present embodiment. The scope of the patent of the utility model, that is, all equivalent changes or modifications made to the spirit disclosed in the utility model, still fall within the scope of the patent of the present utility model.

Claims (9)

1. A gas injection system for preventing a tunnel segment from floating up due to liquefaction is characterized by comprising a monitoring system, a gas injection system and a control system; the monitoring system comprises a pore water pressure sensor, a first displacement sensor and a data acquisition instrument; the pore water pressure sensor is used for measuring the pressure of the penetrating water in the soil body and is arranged in the soil body at different positions of the tunnel; the first displacement sensor is used for detecting the relative displacement between the tunnel segment and the soil outside the segment and is arranged between the outer surface of the tunnel segment and the soil outside the segment; the pore water pressure sensor and the first displacement sensor are connected with the data acquisition instrument in a wired or wireless mode; the gas injection system comprises a gas pump, a pressure regulating valve and a gas pipe which are connected in sequence; the air pump is used for generating compressed air; the pressure regulating valve is used for regulating the pressure of the compressed gas; the gas pipe is used for conveying compressed gas to the liquefied soil body; the control system receives signals from the monitoring system and outputs signals to control operation of the gas injection system.

2. The gas injection system for preventing the tunnel segment from floating up due to liquefaction of claim 1, wherein 8 pore water pressure sensors are uniformly distributed around the circumference of the tunnel.

3. The gas injection system for preventing liquefaction from causing floating up of a tunnel tube sheet of claim 1, wherein the first displacement sensor is a resilient LVDT displacement sensor.

4. The gas injection system for preventing liquefaction from causing floating of a tunnel segment as claimed in claim 1, wherein the pressure regulating valve is an electric pressure regulating valve; and the control system outputs a signal to control the work of the electric pressure regulating valve.

5. The gas injection system for preventing liquefaction from causing floating of a tunnel tube sheet of claim 1, wherein the gas pipe comprises a trunk pipe and a branch pipe; a row of vent holes with the diameter of 1.5-2.5 mm are arranged on the bronchus; the bronchus extends into the liquefied soil body.

6. The gas injection system for preventing the tunnel segment from floating up due to liquefaction of claim 5, wherein the material of the dry gas pipe and the material of the branch gas pipe are polypropylene.

7. The gas injection system for preventing liquefaction from causing uplift of a tunnel tube sheet of claim 1, wherein the monitoring system further comprises a second displacement sensor; the second displacement sensor is used for detecting the relative displacement between the tunnel segments; the second displacement sensor is arranged between the opposite end surfaces of the two connected tunnel segments; the second displacement sensor is connected with the data acquisition instrument in a wired or wireless mode.

8. The gas injection system for preventing liquefaction from causing floating up of a tunnel tube sheet of claim 7, wherein the second displacement sensor is a resilient LVDT displacement sensor.

9. The gas injection system for preventing liquefaction from causing floating up of a tunnel segment as claimed in claim 7, wherein 8 of said second displacement sensors are evenly distributed along the circumference of the tunnel segment.

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