CN211291851U - A Real-time Monitoring System for Earthquake Liquefaction of Shield Tunnel - Google Patents

Abstract

The utility model discloses a real-time monitoring system for seismic liquefaction of shield tunnel soil mass, which comprises a plurality of pore water pressure sensors and data acquisition instruments; the pore water pressure sensor is used to measure the seepage water pressure inside the soil body; In the soil at different positions of the tunnel; the data acquisition instrument is used to collect the signal of the pore water pressure sensor; the pore water pressure sensor is connected with the data acquisition instrument by wired or wireless means. The utility model can real-time and online collect the seepage water pressure inside the soil body at different positions of the shield tunnel; and collect the relative displacement between the outer surface of the shield tunnel segment and the soil outside the segment; the collected data can be further studied , used to guide the design and construction of the actual project; and through the collected data to verify and evaluate the seismic treatment measures.

Description

A Real-time Monitoring System for Earthquake Liquefaction of Shield Tunnel

technical field

The utility model relates to the field of shield tunnels, in particular to a real-time monitoring system for earthquake liquefaction of shield tunnel soil.

Background technique

At present, the shield construction method is generally adopted in the current urban subway tunnels. However, as the strata encountered in the shield construction process become more and more complex, higher requirements are put forward for the shield construction technology. Especially under special stratum conditions, such as the silty-fine sand stratum at the bottom of the tunnel that is easy to liquefy under the action of vibration, the overall shield body "sinks" during the mud-water shield tunneling process, resulting in damage to the formed tunnel segments and misalignment. , water seepage, sand leakage and posture overrun and other quality and safety issues. With the continuous expansion of underground space development, the importance and urgency of the seismic design of underground structures and their safety evaluation are becoming more and more obvious. The seismic response of underground structures has obvious regional characteristics and is closely related to the geological conditions of the site. Seismic liquefaction is very likely to cause serious damage to underground structures, which has become an important research topic in the field of engineering. At present, there is little experience in the seismic design and construction of subways in liquefiable strata, and the current regulations only deal with liquefied strata. In principle, it is difficult to grasp how to implement it in reality. At present, the anti-seismic liquefaction treatment method can adopt the grouting reinforcement method, but this method should be comprehensively determined according to the relationship between the liquefied stratum and the tunnel, the thickness of the liquefied stratum, and the liquefaction grade. The influence of the increase of earth pressure caused by liquefaction should be considered in the calculation of structural bearing capacity, and the influence of the decrease of frictional resistance and the increase of buoyancy should be considered in the calculation of anti-floating stability.

In recent years, high-intensity earthquake disasters have been frequent around the world, and the problem of earthquake resistance and shock absorption of underground structures has gradually attracted great attention and has become an important research direction in the engineering field. Compared with tunnels built by other methods, shield tunnels have a relatively shallow construction history, and most of them are not built in earthquake-prone areas, so there are relatively few earthquake damage data. With the continuous development of underground engineering projects and the increasingly complex construction environment, the problem of seismic design of shield tunnels will emerge more and more before us, and it is necessary to collect liquefaction and other data under the action of earthquakes under various geological conditions , to provide reference and evaluation for subsequent projects.

SUMMARY OF THE INVENTION

The utility model provides a real-time monitoring system for seismic liquefaction of shield tunnel soil mass for comprehensively detecting the seismic characteristics of underground structures in order to solve the technical problems existing in the known technology.

The technical scheme adopted by the utility model to solve the technical problems existing in the known technology is: a real-time monitoring system for the seismic liquefaction of shield tunnel soil mass, comprising a plurality of pore water pressure sensors and a data acquisition instrument; the pore water pressure sensor It is used to measure the seepage water pressure inside the soil body, and it is set in the soil body at different positions of the shield tunnel; the data acquisition instrument is used to collect the signal of the pore water pressure sensor; the pore water pressure sensor is connected by wire or Wirelessly connect with the data acquisition instrument.

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

Further, it also includes a first displacement sensor; the first displacement sensor is used to detect the relative displacement between the shield tunnel segment and the soil outside the segment; the fixing part of the first displacement sensor is arranged on the soil outside the segment. inside the body; the first displacement sensor is connected with the data acquisition instrument in a wired or wireless manner.

Further, the first displacement sensor is a capacitive displacement sensor or an inductive displacement sensor.

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

Further, a plurality of first displacement sensors whose detection directions are perpendicular to the horizontal plane are evenly distributed along the axial direction of the shield tunnel, with an even distribution interval of 5 to 10 meters.

Further, it also includes a second displacement sensor; the second displacement sensor is used to detect the relative displacement between the shield tunnel segments; the fixing part of the second displacement sensor is arranged on two connected shield tunnel segments On the opposite end face of the device; the second displacement sensor is connected with the data acquisition instrument in a wired or wireless manner.

Further, the second displacement sensor is a capacitive displacement sensor or an inductive displacement sensor.

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

Further, on the opposite end faces of the two connected shield tunnel segments, eight second displacement sensors whose detection directions are parallel to the horizontal plane are uniformly distributed in the circumferential direction.

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 shield tunnel; The first displacement sensor used to detect the relative displacement between the shield tunnel segment and the soil outside the segment, etc.; the pore water pressure sensor and the first displacement sensor and other measurement sensors are connected to the data acquisition instrument by wired or wireless means; The seepage water pressure inside the soil at different positions of the shield tunnel and the relative displacement between the shield tunnel segment and the soil outside the segment are collected online in real time by the data acquisition instrument. It can provide online real-time and historical data of the seepage water pressure inside the soil body and the relative displacement between the shield tunnel segment and the soil outside the segment during the construction and use of the shield tunnel, so that the soil liquefaction caused by the tunnel earthquake It can be detected at the first time, and the data can be transmitted to the tunnel safety monitoring personnel in real time through the data acquisition instrument, and corresponding measures can be taken in the shortest time to reduce casualties. A large amount of historical data can also provide reference and evaluation for subsequent projects.

Description of drawings

Figure 1 is a schematic structural diagram of the present invention.

In the figure: 1. Pore water pressure sensor; 2. Second displacement sensor; 3. Signal line; 4. Data acquisition instrument; 5. Soil; 6. 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 real-time monitoring system for seismic liquefaction of shield tunnel soil, including a plurality of pore water pressure sensors 1 and a data acquisition instrument 4 ; the pore water pressure sensor 1 is used to measure the seepage water pressure inside the soil body 5 ; The pore water pressure sensor 1 is arranged in the soil body 5 at different positions of the shield tunnel; the data acquisition instrument 4 is used to collect the signal of the pore water pressure sensor 1; the pore water pressure sensor 1 is wired or Wirelessly connect with the data acquisition instrument 4 . Use the pore water pressure sensor 1 to detect the pore water pressure of the soil body 5 at the tunnel structure, so that the liquefaction of the soil body 5 can be detected at the first time when a tunnel earthquake occurs, and the data can be instantly transmitted to the tunnel through the data acquisition device 4 safety monitoring personnel. Corresponding measures can be taken in the shortest possible time to reduce casualties. The wireless approach reduces a lot of wiring.

Further, in order to detect the seepage water pressure of the soil body 5 at different positions of the shield tunnel, and to make the measurement data more accurate, eight pore water pressure sensors 1 can be evenly distributed around the circumference of the shield tunnel.

Further, a first displacement sensor can also be included; the first displacement sensor can be used to detect the relative displacement between the shield tunnel segment 6 and the soil body 5 outside the segment;

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 5 outside the segment; for example, it can be installed on a rigid support ring embedded in the soil body. If the first displacement sensor is a separate displacement sensor, the separate displacement sensor includes a fixed part and a moving part that moves relatively with the fixed part, and the moving part with the first displacement sensor can be arranged on the outer surface of the segment 6; The relative displacement between the fixed part and the moving part detected by the displacement sensor is the relative displacement between the shield tunnel segment 6 and the soil body 5 outside the segment. 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 6 . The displacement change of the expansion and contraction of the displacement detection head is the relative displacement between the shield tunnel segment 6 and the soil body 5 outside the segment.

The transmission method of the detection signal of the first displacement sensor can be wired or wireless; the first displacement sensor can be connected to the data acquisition instrument 4 by wired or wireless. The wireless approach 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 shield tunnel segment 6. The first displacement sensor is arranged to detect the floating or subsidence of the shield tunnel segment 6 relative to the soil body 5 outside the segment. , and the lateral displacement of the tunnel segment 6 relative to the soil body 5 outside the segment.

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. Preferably, the uniform spacing is 5 to 10 meters. It is convenient to obtain the floating or subsidence of the tunnel segment 6 relative to the soil body 5 outside the segment at multiple positions along the axial direction of the tunnel segment 6 .

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.

Further, it can also include a second displacement sensor 2; the second displacement sensor 2 can be used to detect the relative displacement between the shield tunnel segments 6; the fixed part of the second displacement sensor 2 can be arranged in two adjacent The opposite end face of the shield tunnel segment 6; if the second displacement sensor 2 is a separate displacement sensor, the separate displacement sensor includes a fixed part and a moving part that moves relative to the fixed part, and the separate second displacement sensor The fixed part and the moving part of the The relative displacement between the connected shield tunnel segments 6 . 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 connected shield tunnel segments 6 to make it expand and contract the displacement detection head The part is in contact with the end face of the other shield tunnel segment 6 . The displacement change of the expansion and contraction of the displacement detection head is the relative displacement between the two connected shield tunnel segments 6 .

The transmission method of the detection signal of the second displacement sensor 2 can be wired or wireless; the second displacement sensor 2 can be connected to the data acquisition instrument 4 by wired or wireless. 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 shield tunnel segment 6 , and the second displacement sensor 2 is arranged to detect relative axial and radial displacements between the shield tunnel segments 6 .

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 shield tunnel segments 6 . It is convenient to accurately measure the gap changes in the horizontal direction at each position of the opposite end faces of the two connected shield tunnel segments 6 .

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.

Devices such as the pore water pressure sensor, the first displacement sensor, the second displacement sensor, and the data acquisition instrument can all use applicable products in the prior art.

The present invention also provides an embodiment of a real-time monitoring method for seismic liquefaction of shield tunnel soil mass. The method is: burying a plurality of pore water pressure sensors 1 in the soil mass 5 at different positions of the shield tunnel; Between the outer surface of the segment 6 and the soil body 5 outside the segment, the first displacement sensor for detecting the relative displacement between the shield tunnel segment 6 and the soil body 5 outside the segment is pre-buried; A displacement sensor is connected to the data acquisition instrument 4 by wired or wireless means; the data acquisition instrument 4 online real-time collects the seepage water pressure inside the soil body 5 at different positions of the shield tunnel and the shield tunnel segment 6 and the soil outside the segment 5 relative displacements.

Further, the second displacement sensor 2 for detecting the relative displacement between the shield tunnel segments 6 can be pre-buried on the opposite end faces of the two connected shield tunnel segments 6; 2. Connected to the data acquisition instrument 4 by wired or wireless means; the relative displacement between the shield tunnel segments 6 can be collected online in real time by the data acquisition instrument 4. Eight pore water pressure sensors 1 can be uniformly distributed around the shield tunnel. In this way, the collected data is more balanced, and it is convenient to accurately analyze the seepage water pressure inside the soil body 5 at different positions of the shield tunnel.

A plurality of first displacement sensors whose detection direction is perpendicular to the horizontal plane can be evenly distributed along the axial direction of the shield tunnel, with a uniform spacing of 5 to 10 meters. The first displacement sensor is used to detect the floating or subsidence of the shield tunnel segment 6, and the detection provides the change of the soil body 5 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 real-time monitoring system for seismic liquefaction of shield tunnel soil, comprising a plurality of pore water pressure sensors 1, a first displacement sensor, a second displacement sensor 2 and a data acquisition instrument 4; the pore water pressure sensor 1 is used to measure the internal Seepage water pressure; the first displacement sensor can be used to detect the relative displacement between the shield tunnel segment 6 and the soil body 5 outside the segment; the second displacement sensor 2 can be used to detect the relative displacement between the shield tunnel segment 6; The acquisition instrument 4 receives signals from the pore water pressure sensor 1 , the first displacement sensor and the second displacement sensor 2 .

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.

A construction method for shield tunnel liquefaction observation. The signal line 3 is connected with a pore water pressure sensor 1, a first displacement sensor and a second displacement sensor 2; the fixed part of the second displacement sensor 2 is pre-buried in the shield tunnel segment. In the steel cage of the structure, after fixing, pour concrete; assemble the shield tunnel segment structure; bury the pore water pressure sensor 1 and the fixed part of the first displacement sensor outside the segment through the secondary grouting hole in the segment In the soil body 5; connect the data acquisition instrument 4 to the signal line 3, and the signals collected by the data acquisition instrument 4 can be uploaded to the shield tunnel monitoring center; the collected data can be analyzed by the data acquisition instrument 4 or the monitoring center.

When an underground structure vibrates such as an earthquake, the pore water pressure sensor 1, the first displacement sensor and the second displacement sensor 2 transmit signals to the data acquisition instrument 4, and the data acquisition instrument 4 or the monitoring center analyzes the collected data. Through data analysis, the liquefaction degree of the soil mass 5 around the shield tunnel caused by the magnitude of the earthquake is studied, and the rationality of the seismic measures for the shield tunnel in the water-rich stratum is analyzed and verified.

The standard for judging liquefaction and the range for early warning can be set; the standard for judging liquefaction can be: 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, it is considered that The soil mass 5 is liquefied. The criterion for judging liquefaction can be mainly based on the detection value of the pore water pressure sensor 1 . The first displacement sensor and the second displacement sensor 2 are auxiliary measuring instruments and do not play a major role in determining. When an earthquake occurs, the data monitored by the first displacement sensor and the second displacement sensor 2 are mainly for the reference of scientific researchers.

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 (10)

1. A shield tunnel soil body earthquake liquefaction real-time monitoring system is characterized by comprising a plurality of pore water pressure sensors 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 shield tunnel; the data acquisition instrument is used for acquiring signals of the pore water pressure sensor; the pore water pressure sensor is connected with the data acquisition instrument in a wired or wireless mode.

2. The shield tunnel soil body earthquake liquefaction real-time monitoring system of claim 1, wherein 8 pore water pressure sensors are evenly distributed circumferentially around the shield tunnel.

3. The shield tunnel soil seismic liquefaction real-time monitoring system of claim 1, further comprising a first displacement sensor; the first displacement sensor is used for detecting the relative displacement between the shield tunnel segment and the soil outside the segment; the fixed part of the first displacement sensor is arranged in the soil body outside the pipe piece; the first displacement sensor is connected with the data acquisition instrument in a wired or wireless mode.

4. The shield tunnel soil seismic liquefaction real-time monitoring system of claim 3, wherein the first displacement sensor is a capacitive displacement sensor or an inductive displacement sensor.

5. The shield tunnel soil mass seismic liquefaction real-time monitoring system of claim 4, wherein the first displacement sensor is a resilient LVDT displacement sensor.

6. The shield tunnel soil earthquake liquefaction real-time monitoring system of claim 3, wherein a plurality of first displacement sensors with detection directions perpendicular to the horizontal plane are uniformly distributed along the axial direction of the shield tunnel, and the uniform distribution distance is 5-10 meters.

7. The shield tunnel soil seismic liquefaction real-time monitoring system of claim 1, further comprising a second displacement sensor; the second displacement sensor is used for detecting the relative displacement between the shield tunnel segments; the fixed part of the second displacement sensor is arranged on the opposite end surfaces of the two connected shield tunnel segments; the second displacement sensor is connected with the data acquisition instrument in a wired or wireless mode.

8. The shield tunnel soil seismic liquefaction real-time monitoring system of claim 7, wherein the second displacement sensor is a capacitive displacement sensor or an inductive displacement sensor.

9. The shield tunnel soil mass seismic liquefaction real-time monitoring system of claim 8, wherein the second displacement sensor is a resilient LVDT displacement sensor.

10. The shield tunnel soil earthquake liquefaction real-time monitoring system of claim 7, characterized in that on the opposite end faces of two connected shield tunnel segments, there are circumferentially and uniformly 8 second displacement sensors with detection directions parallel to the horizontal plane.

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