Safety monitoring system for jacking type final joint of immersed tunnel

Abstract

According to the immersed tunnel jacking type final joint safety monitoring system disclosed by the invention, a plurality of deformation monitoring points are arranged between a jacking section and an immersed tube section, a straight line is dragged from the head to the tail of the side part of a thrust steel support along the design axis of the thrust steel support, and the distance from the straight line to each part of the thrust steel support is measured through a caliper; therefore, the coaxiality of the thrust steel support can be measured quickly and simply. Stress meters are symmetrically arranged in the span of the thrust steel support to monitor the cross section and overall stress change of the thrust steel support; a vertical displacement meter and a transverse displacement meter are arranged in the midspan of the thrust steel support, and the midspan deflection deformation of the thrust steel support is monitored; and an angle gauge is arranged at the tail end of the thrust steel support to monitor the vertical and horizontal inclination and rotation conditions of the thrust steel support.

Description

Technical Field

[0001] The present invention belongs to the technical field of immersed tunnel monitoring, and more specifically, relates to a safety monitoring system for the jacking type final joint of an immersed tunnel. Background Art

[0002] The jacking segment method final joint is a new type of final joint form first adopted in immersed tunnels (see Patent CN108755763). Among them, there are relatively prominent safety risks in the structural system conversion link, which is the key to the success of the jacking segment method. To solve the problems of difficult quality inspection of steel support installation and high construction risks during the system conversion construction process, and the structural stability during the post-cast strip and bottom grouting processes, based on the force analysis of the final joint, the present invention realizes the controllable structural safety of the final joint by establishing a targeted monitoring system, laying a foundation for the popularization of the jacking segment method final joint technology. Summary of the Invention

[0003] The purpose of the present invention is to provide a safety monitoring system for the jacking type final joint of an immersed tunnel in view of the deficiencies of the existing technology.

[0004] The present invention is realized through the following technical solutions:

[0005] A safety monitoring system for the jacking type final joint of an immersed tunnel includes the following parts:

[0006] A plurality of deformation monitoring points are arranged between the jacking segment and the immersed tube segment, including: the expansion and contraction deformation monitoring point of the water stop belt, the relative vertical deformation measurement point from the jacking segment to the immersed tube segment, and the relative horizontal deformation measurement point from the jacking segment to the immersed tube segment;

[0007] Drag a straight line along the design axis of the thrust steel support at the side of the thrust steel support, and measure the distance from each point of the thrust steel support to the straight line with a caliper, then the coaxiality of the thrust steel support can be quickly and simply measured;

[0008] Stress gauges are symmetrically arranged at the mid-span of the thrust steel support to monitor the cross-section and overall stress changes of the thrust steel support; vertical and horizontal displacement gauges are arranged at the mid-span of the thrust steel support to monitor the deflection deformation at the mid-span of the thrust steel support; a clinometer is arranged at the tail end of the thrust steel support to monitor the vertical and horizontal inclination and rotation of the thrust steel support.

[0009] In the above technical solution, displacement sensors are used for deformation monitoring. After the displacement sensors are installed, the monitoring cables are introduced into the automatic acquisition instrument in the installed tube segment through the reserved wiring flange for remote automatic monitoring, and the monitoring frequency is not less than 1 time / 5 min.

[0010] In the above technical solution, the design ultimate bearing capacity F1 and the design normal bearing capacity F2 of the thrust steel support are obtained according to the design documents. Take F2 * 1.1 as the pre-pressure F3 of the thrust steel support. Before the formal structural system conversion, two thrust steel supports are grouped and pre-compressed in a centrosymmetric manner, with the pre-pressure being F3. The pre-pressure is divided into 5 levels, and the pressure relief is also divided into 5 levels.

[0011] In the above technical solution, the stress gauge uses a strain sensor with a measuring range of ±1500 με. The axial force of the thrust steel support is calculated by multiplying the cross-sectional area of the thrust steel support by the material elastic modulus and the strain.

[0012] In the above technical solution, the angle gauge selects an attitude angle sensor with three-dimensional channels and an accuracy of not less than 0.01°.

[0013] In the above technical solution, during the conversion of the final joint system and the construction of the post-cast strip, the stress and deformation of the thrust steel support and the deformation of the water stop belt are monitored in real time. When data anomalies occur and do not conform to the law of the pre-compression test data, the construction is immediately stopped; when the monitoring data of a certain thrust steel support is abnormally F4 and exceeds the design safety allowable value, the remaining thrust steel supports are uniformly pressurized, and the pressurization value is F4 / 23 to relieve the structural stress of a single thrust steel support.

[0014] In the above technical solution, during the top grouting construction, to avoid the jacking of the jacking section or the immersed tube section caused by grouting, the settlement of the jacking section and the deformation of the water stop belt are monitored, and the monitoring frequency is not less than 1 time / min. When the change in the monitoring data exceeds 0.2 mm, the grouting is immediately stopped.

[0015] The advantages and beneficial effects of the present invention are as follows:

[0016] The present invention designs a safety monitoring system for the jacking-type final joint of an immersed tube tunnel for the construction method of the final joint of the jacking section method of an immersed tube tunnel, which can realize the monitoring of the telescopic deformation of the water stop belt, the vertical and horizontal deformation monitoring of the jacking section, the coaxiality detection of the thrust steel support, the stress and deformation and rotation monitoring of the thrust steel support, the monitoring during the conversion of the final joint system and the construction of the post-cast strip, and the bottom grouting monitoring of the final joint, so as to realize the safety control of the final joint structure and lay a foundation for the popularization of the final joint technology of the jacking section method. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the construction method of the final joint of an immersed tube tunnel by the jacking section method.

[0018] Figure 2 It is an arrangement diagram of deformation monitoring points set between the jacking section and the immersed tube section.

[0019] Figure 3 It is an arrangement diagram of the coaxiality detection of the thrust steel support.

[0020] Figure 4 It is the layout drawing of the thrust steel support.

[0021] Figure 5 It is the layout drawing of the measuring points for the stress deformation and rotation monitoring of the thrust steel support.

[0022] For those of ordinary skill in the art, without creative efforts, other relevant drawings can be obtained based on the above drawings. Specific embodiments

[0023] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0024] Refer to the appendix Figure 1 , the construction method of the final joint of the immersed tube tunnel by the jacking segment method is as follows: It includes an outer sleeve 1, a jacking segment 2, a water stop belt 4, a jacking system and a locking component. The outer sleeve 1 is sleeved on the connecting end of the buried section. The jacking segment 2 is arranged between the immersed tube section and the outer sleeve 1. The locking component is arranged between the post-poured concrete and the outer sleeve 1 and connects the two. The water stop belt 4 is used for water stop between the outer sleeve 1 and the jacking segment 2. The jacking system is used to jack the jacking segment 2 to make it slide along the tunnel extension direction; a thrust steel support 6 is also preset on the outer sleeve 1, and the thrust steel support 6 is used to lock the outer sleeve 1 and the jacking stage 2; a grouting pipe 7 is arranged on one side of the thrust steel support 6 for fixing the thrust steel support 6.

[0025] For the above-mentioned final joint of the immersed tube tunnel by the jacking segment method, the present invention designs a safety monitoring system for the jacking type final joint of the immersed tube tunnel, including the following parts:

[0026] 1. Analysis and monitoring of the variation law of the jacking segment

[0027] The deformation monitoring between the immersed tube / buried section and the jacking segment is an important criterion for judging the locking quality and safety between the jacking segment and the immersed tube segment / buried section, and is a key parameter for the safety control of the water stop belt. Whether the deformation of the water stop belt is within the control range directly represents whether the waterproof ability is normal. The present invention sets 6 deformation monitoring points between the jacking segment and the immersed tube segment, and the point positions are as Figure 2 , including: 3 water stop belt expansion and contraction deformation monitoring points, 2 relative vertical deformation measuring points from the jacking segment to the immersed tube segment, and 1 relative horizontal deformation measuring point from the jacking segment to the immersed tube segment.

[0028] Displacement sensors are used for deformation monitoring. After the displacement sensors are installed, the monitoring cables are introduced into the automatic acquisition instrument in the installed pipe segment through the reserved wiring flange for remote automatic monitoring, and the monitoring frequency is not less than 1 time / 5 min. The monitoring system shall have the functions of remote data transmission and remote control.

[0029] 2. Coaxiality test of thrust steel support

[0030] The thrust steel support is placed on site for a long time, and uneven force may cause certain flexural deformation; in addition, the thrust steel support is affected by long-term seawater corrosion and processing accuracy, and may not meet the coaxiality requirements of the existing design after the connection is completed, so accurate methods are needed for detection. It is difficult to accurately measure the coaxial deviation of the steel support by traditional total station point measurement.

[0031] See attached Figure 3 The present invention drags a straight line along the design axis of the thrust steel support from beginning to end on the side of the thrust steel support 6, and measures the distance of the straight line to various places of the thrust steel support with a caliper, so that the coaxiality of the thrust steel support can be quickly and simply measured.

[0032] 3. Thrust steel support preloading process before system conversion

[0033] See attached Figure 4 There are 24 thrust steel supports in the jacking section, including 10 at the top plate, 2 at the side wall and 12 at the bottom plate. According to the design documents, the design ultimate bearing capacity F1 and the design normal bearing capacity F2 of the thrust steel support are obtained, and F2*1.1 is taken as the preload F3 of the thrust steel support. Before the formal structural system conversion, two thrust steel supports are grouped as a group and preloaded in a centrally symmetrical manner. The preload is F3, and the preload is divided into 5 levels. The pressure relief is also divided into 5 levels. Relevant data is collected for each level after it is stable without abnormal sound and after the jack pressure changes.

[0034] 4. Monitoring of force deformation and rotation of thrust steel support

[0035] Each thrust steel support needs to be monitored for stress and deformation to avoid damage to the thrust steel support and failure to meet the support function of the jacking segment. The stress monitoring of the thrust steel support can directly indicate the magnitude of its stress, and can effectively determine whether the stress of each thrust steel support is consistent and whether there is eccentric stress. The deformation and rotation monitoring of the thrust steel support can clearly show whether the thrust steel support has abnormal stress and deformation. See the attached Figure 5 The present invention symmetrically arranges stress gauges s1 in the middle of the thrust steel support span to monitor the cross-section and overall stress changes of the thrust steel support; arranges vertical and lateral displacement gauges s2 in the middle of the thrust steel support span to monitor the deflection deformation in the middle of the thrust steel support span; arranges an inclinometer s3 at the tail end of the thrust steel support to monitor the vertical and horizontal inclination and rotation of the thrust steel support in real time.

[0036] Furthermore, the stress gauge uses a strain sensor with a measuring range of ±1500 με. The axial force of the thrust steel support is calculated by multiplying the cross-sectional area of the thrust steel support by the elastic modulus of the material and the strain. The angle gauge selects a three-dimensional attitude angle sensor with an accuracy of 0.01°. Automated monitoring is carried out at each measuring point, and the monitoring frequency is not less than 1 time per 5 minutes. The monitoring system shall have the functions of remote data transmission and remote control to meet the high standards of real-time monitoring.

[0037] Before the system conversion, a preloading test is carried out. The stability of the thrust steel support under load is checked by the displacement and rotation of the thrust steel support. Whether there is eccentric loading on the thrust steel support is detected through the monitoring data of the axial force of the thrust steel support. The stability of the hydraulic system is checked in combination with the numerical value of the jack oil gauge. The overall stability of the jacking section is checked in combination with the expansion and contraction deformation data of the water stop belt.

[0038] 5. Monitoring during the system conversion of the final joint and during the construction of the post-cast strip

[0039] The stress and deformation of the thrust steel support and the deformation of the water stop belt are monitored in real time. When data anomalies occur and do not conform to the data pattern of the preloading test, the construction shall be stopped immediately.

[0040] When the monitoring data of a certain thrust steel support is abnormally F4 and exceeds the design safety allowable value, the remaining thrust steel supports are uniformly pressurized, and the pressurization value is F4 / 23 to relieve the structural stress of a single thrust steel support.

[0041] 6. Monitoring of bottom grouting of the final joint

[0042] During the top grouting construction, in order to avoid the jacking of the jacking section or the immersed tube section caused by grouting, settlement monitoring and water stop belt deformation monitoring are carried out on the jacking section, and the monitoring frequency is not less than 1 time per minute. When the change of each monitoring data exceeds 0.2 mm, the grouting shall be stopped immediately.

[0043] The above makes an exemplary description of the present invention. It should be noted that without departing from the core of the present invention, any simple deformation, modification or equivalent replacement that can be made by those skilled in the art without creative labor falls within the protection scope of the present invention.

Claims

1. A safety monitoring system for the final joint of an immersed tube tunnel jacking type, characterized in that: Includes the following sections: Multiple deformation monitoring points are set between the jacking section and the immersed tube section, including: water stop expansion and contraction deformation monitoring point, relative vertical deformation measurement point between the jacking section and the immersed tube section, and relative horizontal deformation measurement point between the jacking section and the immersed tube section; Drag a straight line along the design axis of the thrust steel support from beginning to end on the side of the thrust steel support, and use a caliper to measure the distance of the straight line from each point of the thrust steel support to quickly and easily measure the coaxiality of the thrust steel support; Stress gauges are arranged symmetrically in the mid-span of the thrust steel support to monitor the changes in the cross-section and overall stress of the thrust steel support; vertical and lateral displacement gauges are arranged in the mid-span of the thrust steel support to monitor the deflection deformation in the mid-span of the thrust steel support; inclinometers are arranged at the tail end of the thrust steel support to monitor the vertical and horizontal inclination and rotation of the thrust steel support.

2. The immersed tube tunnel jacking type final joint safety monitoring system according to claim 1 is characterized by: Deformation monitoring uses displacement sensors. After the displacement sensor is installed, the monitoring cable is introduced into the automatic data collector in the installed pipe section through the reserved wiring flange for remote automatic monitoring. The monitoring frequency is not less than 1 time / 5 minutes.

3. The immersed tube tunnel jacking type final joint safety monitoring system according to claim 1 is characterized by: According to the design documents, the design ultimate bearing capacity F1 and the design normal bearing capacity F2 of the thrust steel support are obtained, and F2*1.1 is taken as the preload pressure F3 of the thrust steel support. Before the formal structural system conversion, two thrust steel supports are grouped as a group and preloaded in a centrally symmetrical manner. The preload pressure is F3. The preload pressure is divided into 5 levels, and the pressure relief is also divided into 5 levels.

4. The immersed tube tunnel jacking type final joint safety monitoring system according to claim 1 is characterized by: The stress gauge uses a strain sensor with a range of ±1500με, and the thrust steel support axial force is calculated by the thrust steel support cross-sectional area × material elastic modulus × strain.

5. The immersed tube tunnel jacking type final joint safety monitoring system according to claim 1 is characterized by: The channel of the inclinometer is a three-dimensional attitude angle sensor with an accuracy of not less than 0.01°.

6. The immersed tube tunnel jacking type final joint safety monitoring system according to claim 1 is characterized by: During the final joint system conversion and the post-casting strip construction, the stress deformation of the thrust steel support and the deformation of the waterstop are monitored in real time. When abnormal data occurs and does not conform to the preload test data pattern, construction is stopped immediately. When the monitoring data of a thrust steel support is abnormal to F4 and exceeds the design safety allowable value, the remaining thrust steel supports are uniformly pressurized with a value of F4 / 23 to relieve the stress on the single thrust steel support structure.

7. The immersed tube tunnel jacking type final joint safety monitoring system according to claim 1 is characterized by: During the top grouting construction, in order to avoid the jacking of the jacking section or the immersed pipe section caused by grouting, the settlement of the jacking section and the deformation of the waterstop are monitored, and the monitoring frequency is not less than 1 time / min; when the change of each monitoring data exceeds 0.2mm, the grouting is stopped immediately.

Images