A method for monitoring deformation of shield-driven underground continuous wall construction

Abstract

The present invention discloses a monitoring scheme for deformation of underground continuous wall construction when shield is used to break through the underground continuous wall. Two holes are drilled on both sides of the top of the underground continuous wall to be monitored, and distributed optical fiber temperature strain sensors and steel bars bundled with optical fiber sensors are arranged in the holes. Concrete of the same grade as that of the underground continuous wall is backfilled; a static level is arranged on the top of the underground continuous wall. The present invention monitors the underground continuous wall when the shield breaks through the underground continuous wall, and is divided into upper and lower parts to monitor the wall before, during and after the shield cutting. The data of internal deformation and external settlement of the underground continuous wall during construction can be collected in real time, and deformation can be predicted using the collected data, which provides safety guarantee for construction. At the same time, it also effectively improves the efficiency of construction monitoring, enriches the monitoring content, and provides data support for related research.

Description

Technical Field

[0001] The invention relates to a method for monitoring construction deformation of a shield-driven underground continuous wall, belonging to the technical field of construction monitoring. Background Art

[0002] With the acceleration of urbanization, the construction of urban rail transit in my country has developed rapidly. In the process of urban rail transit lines being networked, it is inevitable that new lines will pass under existing stations. my country's subway stations often use underground continuous walls as enclosure structures, and section tunnels are often built using the shield method. Section tunnels passing under existing stations need to pass through the underground continuous walls on both sides of the existing line. If the shield can directly pass through the underground continuous wall, it will greatly save construction time and cost, but due to the high risk of project implementation, it is necessary to monitor the deformation of the underground continuous wall during the cutting process. At present, the theory related to the direct passage of the shield through the underground continuous wall is not perfect enough, and there is a lack of corresponding underground continuous wall deformation monitoring solutions. The common method is to monitor the horizontal and vertical displacement of the underground continuous wall through inclinometers, total stations, etc., but how to monitor the deformation inside the underground continuous wall in real time is still a difficult problem. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a method for monitoring deformation of shield-driven underground continuous wall construction, thereby achieving real-time monitoring of deformation, top settlement, etc. of reinforced concrete inside the underground continuous wall.

[0004] To achieve the above-mentioned purpose of the invention, the technical solution adopted by the present invention is to provide a method for monitoring deformation of shield-driven underground continuous wall construction, comprising the following steps:

[0005] (1) Drill a hole with a diameter of 90 to 110 mm on both sides of the shield machine working face at the top of the underground continuous wall construction section to be monitored, and the bottom of the hole is 3 to 4 m below the bottom of the shield machine working face;

[0006] (2) The hole is divided into two monitoring areas, an upper monitoring area and a lower monitoring area. The area above the top of the shield machine working face is the upper monitoring area of ​​the hole, and the area below the top is the lower monitoring area of ​​the hole. Steel bars are arranged in each hole. Two groups of distributed optical fiber temperature and strain sensors are arranged in the hole of the upper monitoring area, one of which is tied to the upper part of the steel bars. A group of distributed optical fiber temperature and strain sensors tied to the lower part of the steel bars is arranged in the hole of the lower monitoring area. The output end of the sensor is connected to a demodulator.

[0007] (3) Backfill the hole with backfill concrete of the same grade as the underground continuous wall concrete, fix the distributed optical fiber temperature strain sensor and steel bars in the hole, and solidify them together with the underground continuous wall;

[0008] (4) Before the shield machine starts working and cuts the steel bars, the demodulator collects sensor signals from the upper and lower monitoring areas in the hole to monitor the deformation of the shield breaking through the underground continuous wall. After the shield machine cuts off the lower steel bars in the hole, the demodulator collects two sets of sensor signals from the upper monitoring area in the hole to monitor the deformation of the shield breaking through the underground continuous wall.

[0009] In the technical solution of the present invention, each group of distributed optical fiber temperature strain sensors includes a stress optical fiber sensor and a temperature measurement optical fiber sensor.

[0010] The method for monitoring deformation of shield-driven underground continuous wall construction disclosed by the present invention further comprises arranging a static level on the top of the underground continuous wall construction section to be monitored.

[0011] Compared with the prior art, the present invention has the following advantages and positive effects:

[0012] 1. When the shield machine breaks through the underground continuous wall, the present invention monitors the underground continuous wall by dividing it into two parts, the upper and lower parts, to monitor the wall before, during and after the shield cutting. It can effectively collect data on the internal deformation and external settlement of the underground continuous wall during construction, use the collected data to predict the deformation, effectively cooperate with the theoretical research on direct shield cutting of the underground continuous wall, improve the construction monitoring efficiency, ensure construction safety, and save construction time and cost.

[0013] 2. The present invention adopts distributed optical fiber temperature and strain sensors, which are respectively used to collect the steel bar stress data, concrete stress data, and temperature compensation data inside the underground continuous wall, and obtain the strain and deformation of the steel bar and concrete during the construction process, which solves the problem of monitoring the internal deformation and external settlement of the underground continuous wall when the shield breaks through the underground continuous wall, effectively improves the monitoring efficiency, enriches the monitoring content, and provides safety protection for construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 , 2 They are respectively a cross-sectional and top view schematic diagram of a structure for monitoring deformation during shield tunneling construction of underground continuous walls according to an embodiment of the present invention;

[0015] In the figure: 1. Underground continuous wall; 2. Backfill concrete; 3. Shield machine; 4. Demodulator; 5. Steel bars; 6. Distributed fiber optic temperature strain sensor; 7. Drill hole; 8. Static level. DETAILED DESCRIPTION

[0016] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and embodiments.

[0017] Example 1

[0018] See attached Figure 1 and Figure 2 , are respectively a cross-sectional view and a top view of the monitoring structure provided by a monitoring method for shield-breaking underground continuous wall construction deformation in this embodiment. Two boreholes 7 are drilled at the top of the underground continuous wall 1 to be monitored, and the hole diameter does not exceed the thickness of the underground continuous wall. Distributed optical fiber temperature and strain sensors 6 and steel bars 5 bundled with optical fiber sensors are arranged in the boreholes, and the output end of the sensor is connected to the demodulator 4; after the arrangement is completed, backfill concrete 2 with the same concrete grade as the underground continuous wall 1 is filled. The distributed optical fiber temperature and strain sensor includes stress optical fiber and temperature measurement optical fiber according to its function, which are used to collect steel bar stress data, concrete stress data, and temperature compensation data inside the underground continuous wall, respectively, to obtain the strain and deformation of steel bars and concrete during the construction process, and provide data support for construction safety and related research.

[0019] In this embodiment, in order to measure the settlement of the top of the underground continuous wall 1, the construction monitoring structure also includes a static level 8 arranged on the top of the underground continuous wall 1 to accurately monitor the settlement of the top of the underground continuous wall 1.

[0020] The monitoring method provided by the present invention has the following construction steps for its monitoring structure:

[0021] 1. Two boreholes 7 with an aperture of 90-110 mm are drilled on both sides of the top of the underground continuous wall 1 construction section, i.e., the top of the shield crossing section. The bottom depth of the borehole 7 exceeds the bottom of the shield machine working face of the construction section by 3-4 m; distributed optical fiber temperature and strain sensors 6 and steel bars 5 are arranged in the borehole 7. The specific method is as follows: Each hole is divided into upper and lower monitoring areas. The upper part of the hole is the upper monitoring area, and the lower part is the lower monitoring area; steel bars are arranged in each borehole, and two groups of distributed optical fiber temperature and strain sensors are arranged in the hole of the upper monitoring area. Each group of sensors includes a stress optical fiber sensor and a temperature measurement optical fiber sensor, and one group is tied to the upper part of the steel bar; a group of distributed optical fiber temperature and strain sensors tied to the steel bar is arranged in the hole of the lower monitoring area.

[0022] 2. Connect each group of distributed optical fiber temperature strain sensors 6 to the demodulator 4, and backfill the borehole with concrete 2 of the same grade as that of the underground continuous wall 1 to ensure that the internal deformation of the entire underground continuous wall 1 is monitored;

[0023] 3. A static level 8 is arranged on the top of the underground continuous wall 1 to monitor the top settlement of the underground continuous wall 1.

[0024] By adopting the monitoring method provided by the present invention, in actual construction monitoring, distributed optical fiber temperature and strain sensors are used to continuously collect temperature and strain information for strain, temperature and vibration at each point along the optical fiber sensor through the principle of light time domain measurement. In this embodiment, each group of optical fiber sensors includes a stress optical fiber sensor and a temperature measurement optical fiber sensor, and the optical fiber lengths of each group of optical fiber sensors are equal. The appropriate length can be selected according to the height of the underground continuous wall and the diameter of the shield machine working surface according to the monitoring needs.

[0025] When monitoring the working status, a group of optical fiber sensors in the upper monitoring area of ​​each borehole are used to monitor the deformation of concrete and steel bars respectively. A group of optical fiber sensors used to monitor the deformation of steel bars are tied to the laid steel bars, and a group of optical fiber sensors used to monitor the deformation of concrete do not need to be tied to the steel bars; a group of optical fiber sensors in the lower monitoring area are tied to the steel bars to monitor the deformation data of the steel bars. When the shield machine starts working but before cutting the steel bars, the optical fiber sensors in the upper and lower monitoring areas of the borehole work simultaneously, the temperature measuring optical fiber is used to demodulate the temperature signal, and the stress optical fiber is used to demodulate the deformation signal; when the shield machine cuts off the steel bars and a group of optical fibers in the lower monitoring area, only the two groups of optical fibers in the upper monitoring area continue to monitor until the monitoring is completed.

[0026] In this embodiment, the internal deformation data of the underground continuous wall collected by the demodulator and the settlement data collected by the top static level can be input into the computer for calculation and analysis to obtain the predicted deformation values ​​inside and outside the wall when the shield passes through the underground continuous wall, thereby providing guarantee for construction safety.

Claims

1. A method for monitoring deformation of shield-driven underground continuous wall construction, characterized in that The steps include: (1) Drill a hole with a diameter of 90 to 110 mm on both sides of the shield machine working face at the top of the underground continuous wall construction section to be monitored, and the bottom of the hole is 3 to 4 m below the bottom of the shield machine working face; (2) The hole is divided into two monitoring areas, an upper monitoring area and a lower monitoring area. The area above the top of the shield machine working face is the upper monitoring area of ​​the hole, and the area below the top is the lower monitoring area of ​​the hole. Steel bars are arranged in each hole. Two groups of distributed optical fiber temperature and strain sensors are arranged in the hole of the upper monitoring area, one of which is tied to the upper part of the steel bars. A group of distributed optical fiber temperature and strain sensors tied to the lower part of the steel bars is arranged in the hole of the lower monitoring area. The output end of the sensor is connected to a demodulator. (3) Backfill the hole with backfill concrete of the same grade as the underground continuous wall concrete, fix the distributed optical fiber temperature strain sensor and steel bars in the hole, and solidify them together with the underground continuous wall; (4) Before the shield machine starts working and cuts the steel bars, the demodulator collects sensor signals from the upper and lower monitoring areas in the hole to monitor the deformation of the shield breaking through the underground continuous wall. After the shield machine cuts off the lower steel bars in the hole, the demodulator collects two sets of sensor signals from the upper monitoring area in the hole to monitor the deformation of the shield breaking through the underground continuous wall.

2. A method for monitoring deformation of shield-driven underground continuous wall construction according to claim 1, characterized in that: Each group of distributed optical fiber temperature strain sensors includes a stress optical fiber sensor and a temperature measurement optical fiber sensor.

3. A method for monitoring deformation of shield-driven underground continuous wall construction according to claim 1, characterized in that: A static level is laid out at the top of the underground continuous wall construction section to be monitored.

Images