A method for adjusting the settlement data collection frequency of a fully overlapping section of an overlapping tunnel

Abstract

The present invention relates to a method for adjusting the collection frequency of settlement data in a fully overlapping section of an overlapping tunnel. The method at least includes: monitoring the ground settlement caused by the shield tunneling of the first-started tunnel and collecting relevant data of the ground settlement; monitoring the secondary vibration impact caused by the shield tunneling of the later-started tunnel and collecting relevant data of the ground settlement; adjusting the collection frequency of the settlement data based on the change of the first and / or second distance between the tunneling face and the monitoring section. Aiming at the defect that settlement data is collected at the same frequency at each monitoring point in the prior art, the adjustment method of the collection frequency of the settlement data of the present invention can reduce the collection and storage of a large amount of invalid data.

Description

[0001] This application is a divisional application of a patent application with the application number 202210327480.7, the application date of March 31, 2022, the invention title of a monitoring device and method for the fully overlapping section of an up-and-down overlapping tunnel, and the patent type of invention. Technical Field

[0002] The present invention relates to the technical field of overlapping tunnel construction, and in particular to a method for adjusting the settlement data collection frequency of the fully overlapping section of an overlapping tunnel. Background Art

[0003] During the construction of subway tunnels, the disturbance to the ground surface is inevitable. Among various construction methods, the shield method has relatively less disturbance to the ground surface. Since most subway interval constructions are in relatively prosperous and densely populated areas of the city, if the ground surface deformation is greater than the deformation critical value, it will have a greater impact on surrounding high-rise buildings, roads, underground pipelines, etc. Therefore, it is particularly important to monitor the shield tunnel section to feedback the construction.

[0004] With the development and utilization of underground space, more and more tunnels begin to adopt an up-and-down overlapping layout. The influence range and magnitude of shield up-and-down overlapping construction on the upper ground surface are completely different from those of normal parallel tunnels, and there is no existing experience for reference.

[0005] During the shield propulsion process, the superstructure above it or people will be affected by the vibration of the foundation or ground surface caused by it and the resulting secondary vibration. In particular, it will have an impact on the structural safety of ancient and old buildings. In addition, it may cause people to feel discomfort to varying degrees, thus affecting people's physical health and interfering with people's normal life. Especially when constructing the upward tunnel, the impact on the upper part is greater.

[0006] The prior art discloses some related technical solutions, but does not solve the above technical problems.

[0007] For example, Chinese Patent Document CN103277110 A discloses a construction method for an overlapping shield tunnel. The construction steps include: driving construction of the downward shield tunnel, and the tunnel structure adopts reinforced segments; grouting the soil mass sandwiched between the upward tunnel and the downward tunnel through a grouting pipe in the secondary grouting hole of the downward tunnel; setting up a trolley support system in the downward tunnel before the construction of the upward tunnel to protect the downward tunnel; driving construction of the upward shield tunnel, and during the construction process, the support trolley of the downward tunnel keeps following up synchronously with the driving of the upward tunnel; grouting the soil mass sandwiched between the upward tunnel and the downward tunnel through a grouting pipe in the secondary grouting hole of the upward tunnel.

[0008] For example, Chinese Patent Document CN105332710 A discloses a construction method for an upper and lower overlapping tunnel suitable for small clear distance and long distance in soft geology. The upper and lower overlapping tunnels include an upper tunnel and a lower tunnel with the same tunnel diameter and approximately equal tunnel lengths. Both the upper tunnel and the lower tunnel are formed into tunnel structures by segment linings. The vertical clear distance between the upper tunnel and the lower tunnel is less than 0.7D (shield diameter), and the tunnel length is greater than 1000 m. Its shield construction method is to complete the lower tunnel according to the conventional shield construction method, and then, through measures such as a shield high-altitude launching platform, deep-hole grouting reinforcement of the soil mass in the interlayer between the upper and lower tunnels, reinforcement of the support steel ring of the lower tunnel, and a shield high-altitude receiving platform, etc., to reduce the influence of the shield construction of the upper tunnel on the formed lower tunnel and the secondary superposition effect of the settlement of the overlapping tunnels, and ensure that the deformation of the lower tunnel and the ground settlement are controllable.

[0009] The above-mentioned prior arts do not involve the problem of the installation of monitoring points in the completely overlapping section, and thus do not solve the problem proposed by the present invention: how to monitor and reduce the vibration influence during the construction of the overlapping tunnels.

[0010] In addition, on the one hand, there are differences in the understanding of those skilled in the art; on the other hand, although the applicant has studied a large number of documents and patents when making the present invention, all details and contents are not listed in detail due to space limitations. However, this does not mean that the present invention does not possess the features of these prior arts. On the contrary, the present invention already possesses all the features of the prior arts, and the applicant reserves the right to add relevant prior arts in the background art. Summary of the Invention

[0011] Aiming at the deficiencies of the prior art, the present invention provides a monitoring method for the completely overlapping section of an upper and lower overlapping tunnel. At least one vertical plane perpendicular to the axis of the overlapping tunnel is selected as the monitoring section of the overlapping tunnel based on the overlapping degree between the overlapping tunnels, the number of monitoring points arranged on the monitoring section is determined based on the clear distance and / or angle between the overlapping tunnels corresponding to the monitoring section, and the settlement data processing and analysis are carried out based on the settlement data sent by the monitoring points.

[0012] The present invention monitors the influence of surface settlement caused during the construction process of the overlapping tunnel throughout the whole process. It can not only collect the surface settlement data caused by the first launched tunnel, but also monitor the influence of the later launched tunnel on the first launched tunnel and the surface settlement. Through the selection of the monitoring section and the arrangement of the monitoring points, the lateral settlement data from one monitoring section to another and the longitudinal monitoring data of the monitoring points arranged along the monitoring section can be collected, forming a three-dimensional monitoring, and the detection result is more accurate.

[0013] Preferably, the slump is related to the horizontal distance, vertical distance, and radius of the tunnel axis between at least two tunnels, S = (L, H, R1, R2), where S represents the slump, L represents the horizontal distance of the tunnel axis, H represents the vertical distance of the tunnel axis, R1 represents the radius of the first tunnel, and R2 represents the radius of the second tunnel.

[0014] Preferably, the net spacing and / or angle between the overlapping tunnels are related to the maximum settlement value.

[0015] Based on the correlation between the net spacing and / or angle between the tunnels and the maximum settlement value, set the number and distribution range of the monitoring points.

[0016] Preferably, the method further includes: adjusting the collection frequency of the settlement data based on the change in the first and / or second distance between the tunneling face and the monitoring section.

[0017] Preferably, when the first and / or second distance between the tunneling face and the monitoring section is not greater than the first threshold, the collection frequency of the settlement data is the first frequency; when the first and / or second distance between the tunneling face and the monitoring section is greater than the first threshold and not greater than the second threshold, the collection frequency of the settlement data is the second frequency; when the first and / or second distance between the tunneling face and the monitoring section is greater than the second threshold, the collection frequency of the settlement data is the third frequency.

[0018] Preferably, the method further includes: adjusting the collection frequency of the settlement data to the fourth frequency when the surface settlement is stable.

[0019] Preferably, the method further includes: increasing the collection frequency of the settlement data when the surface settlement is abnormal.

[0020] The present invention dynamically adjusts the data collection frequency of each monitoring section based on the change of the tunneling face, improves the effective utilization of the data, and reduces the collection of data with less effect on data analysis.

[0021] Preferably, the method further includes: predicting the maximum settlement amount based on the settlement-time distribution fitting curve of the surface settlement.

[0022] Preferably, the conditions for the surface settlement to reach stability at least include:

[0023] The settlement speed of the road and the surface shows an obvious decreasing trend;

[0024] The convergence speed of the road and the surface settlement is less than 0.01 - 0.04 mm / day;

[0025] The convergence amount reaches 80% or more of the total convergence amount.

[0026] By predicting the maximum settlement, the present invention can reinforce the parts with large settlements to ensure the normal progress of the shield construction process and prevent significant impacts on surrounding buildings. During the entire construction process of the present invention, monitoring can be carried out throughout the process, with a small capital investment, to avoid major construction hazards during the construction process.

[0027] The present invention also provides a monitoring device for the completely overlapping section of an up-and-down overlapping tunnel, which includes at least several monitoring units. After being buried underground, the monitoring units form monitoring points for monitoring the surface settlement. The monitoring section where the monitoring points are located is at least one vertical plane perpendicular to the axis of the overlapping tunnel selected based on the overlapping degree between the overlapping tunnels. The number of monitoring points in the monitoring section is determined based on the net distance and / or angle between the overlapping tunnels corresponding to the monitoring section. Among them, the monitoring unit is a sensor capable of monitoring the surface settlement.

[0028] The monitoring device of the present invention only needs to bury the monitoring points once to monitor the surface settlement caused by the tunnels starting successively, form a three-dimensional monitoring, and through the processing and analysis of the data, combined with the specific construction situation, it can judge the reasons for the surface settlement, take relevant measures to reduce the surface settlement, and at the same time can achieve full-process monitoring, further enhancing the effect of information-based construction, providing a communication channel for the construction and supervision units, evaluating the safety status of the soil body, and putting forward reasonable construction suggestion measures to ensure the safe construction of the subway project.

[0029] The present invention also provides a method for adjusting the collection frequency of settlement data for the completely overlapping section of an overlapping tunnel. The method at least includes: monitoring the surface settlement caused by the first-starting tunnel during the shield process and collecting relevant data on the surface settlement; monitoring the secondary vibration impact caused by the shield process of the later-starting tunnel and collecting relevant data on the surface settlement; adjusting the collection frequency of the settlement data based on the change in the first and / or second distance between the tunneling face and the monitoring section.

[0030] Among them, when the first and / or second distance between the tunneling face and the monitoring section is not greater than the first threshold, the collection frequency of the settlement data is the first frequency; when the first and / or second distance between the tunneling face and the monitoring section is greater than the first threshold and not greater than the second threshold, the collection frequency of the settlement data is the second frequency; when the first and / or second distance between the tunneling face and the monitoring section is greater than the second threshold, the collection frequency of the settlement data is the third frequency.

[0031] Preferably, the method further includes: adjusting the collection frequency of the settlement data to the fourth frequency when the surface settlement is stable.

[0032] Preferably, the method further includes:

[0033] When the surface settlement is abnormal, the collection frequency of the settlement data increases.

[0034] Preferably, the method further includes: predicting the maximum settlement amount based on the settlement-time distribution fitting curve of the ground settlement, and strengthening the interlayer soil at the locations with larger settlement amounts.

[0035] Preferably, the method further includes: determining the number and distribution range of the monitoring points arranged at the monitoring section based on the net spacing and / or angle between the overlapping tunnels corresponding to the monitoring section.

[0036] Preferably, the method further includes: when the angle between the two overlapping tunnels is in the range of 40° to 60°, if the net spacing between the two tunnels is fixed, as the angle between the two overlapping tunnels decreases, more monitoring points are arranged within the range affected by settlement, and the detection frequency is increased.

[0037] Preferably, the method further includes: when the angle between the two overlapping tunnels is in the range of 40° to 60°, if the angle between the two tunnels remains unchanged, as the net spacing increases, more monitoring points are arranged, and the density of the arranged monitoring points and the detection frequency are correspondingly reduced.

[0038] Preferably, the method further includes: at the first monitoring section where the angle between the two overlapping tunnels is 0°, two or four monitoring points are arranged at the first monitoring section.

[0039] Preferably, the first threshold is 20 m, and the first frequency is once a day; the second threshold is 50 m, and the second frequency is once every two days; the third frequency is once a week, and the fourth frequency is once a month.

[0040] Preferably, the conditions for the ground settlement to reach stability at least include: there is an obvious trend of slowdown in the settlement speed of the road and the ground; the convergence speed of the road and the ground settlement is less than 0.01 - 0.04 mm / day; the convergence amount reaches 80% or more of the total convergence amount. Description of the Drawings

[0041] Figure 1 is a schematic diagram of the layout of the ground settlement monitoring points in the overlapping section provided by the present invention;

[0042] Figure 2 is a schematic diagram of the embedding of the reference point provided by the present invention;

[0043] Figure 3 is an enlarged schematic diagram of the monitoring working base point provided by the present invention;

[0044] Figure 4 is a schematic diagram of the overlapping degree division elements provided by the present invention;

[0045] Figure 5 is a schematic diagram of the settlement amount curves of each monitoring section provided by the present invention;

[0046] Figure 6 It is a schematic diagram of the longitudinal settlement of the D1 section of the first tunnel construction provided by the present invention;

[0047] Figure 7 It is a schematic diagram of the longitudinal settlement of the D2 section of the first tunnel construction provided by the present invention;

[0048] Figure 8 It is a schematic diagram of the longitudinal settlement of the D3 section of the first tunnel construction provided by the present invention;

[0049] Figure 9 It is a schematic diagram of the longitudinal settlement of the D4 section of the first tunnel construction provided by the present invention;

[0050] Figure 10 It is a schematic diagram of the longitudinal settlement of the D5 section of the first tunnel construction provided by the present invention;

[0051] Figure 11 It is a schematic diagram of the longitudinal settlement of the D6 section of the first tunnel construction provided by the present invention.

[0052] List of reference numerals

[0053] 1: First tunnel; 2: Second tunnel; 101: Protection pipe; 102: Outer pipe; 103: Suspended clamp; 104: Benchmark; 105: Borehole; 106: Base of reference point; DB1-1: First monitoring point of the first monitoring section; DB1-4: Fourth monitoring point of the first monitoring section; DB2-1: First monitoring point of the second monitoring section; DB2-12: Twelfth monitoring point of the second monitoring section; DB3-1: First monitoring point of the third monitoring section; DB3-2: Second monitoring point of the third monitoring section; DB4-1: First monitoring point of the fourth monitoring section; DB4-14: Fourteenth monitoring point of the fourth monitoring section; DB5-1: First monitoring point of the fifth monitoring section; DB5-2: Second monitoring point of the fifth monitoring section; DB6-1: First monitoring point of the sixth monitoring section; DB6-2: Second monitoring point of the sixth monitoring section. Detailed implementation manners

[0054] The following is a detailed description with reference to the accompanying drawings.

[0055] Based on the deficiencies of the prior art, the present invention provides a monitoring method and device for the fully overlapping section of an up-and-down overlapping tunnel. The present invention can also provide a dynamic three-dimensional monitoring method and device for the fully overlapping section of an overlapping tunnel.

[0056] The monitoring method for the fully overlapping section of the up-and-down overlapping tunnel of the present invention at least includes: selecting at least one vertical plane perpendicular to the axis of the overlapping tunnel as the monitoring section of the overlapping tunnel based on the overlapping degree between the overlapping tunnels, determining the number of monitoring points arranged on this monitoring section based on the net distance and / or angle between the overlapping tunnels corresponding to the monitoring section, and performing settlement data processing and analysis based on the settlement data sent by the monitoring points.

[0057] The monitoring section where the monitoring points are located is determined according to the actual needs of the project.

[0058] The overlapping degree is related to the horizontal distance, vertical distance, and radius of the tunnel axes between at least two tunnels. As Figure 4 shown, S=(L, H, R1, R2), where S represents the overlapping degree, L represents the horizontal distance of the tunnel axis, H represents the vertical distance of the tunnel axis, R1 represents the radius of the first tunnel, and R2 represents the radius of the second tunnel.

[0059] The number of monitoring points arranged on the monitoring section is determined based on the net distance and / or angle between the overlapping tunnels.

[0060] The net distance and / or angle between the overlapping tunnels are related to the maximum settlement value. Therefore, the number and distribution range of the monitoring points are set based on the correlation between the net distance and / or angle between the tunnels and the maximum settlement value.

[0061] Specifically, the number of monitoring points on the monitoring section is set according to the following net distance and / or angle conditions. In the present invention, the tunnel diameter is set to D, which is 2m. The net distance refers to the length of the connection line between the centers of the two tunnel cross-sections minus the length of one tunnel diameter.

[0062] When the shallow-buried double-hole tunnels are horizontally arranged and the net distance between the two tunnels is small, the mutual influence between them is particularly large.

[0063] When the net distance is less than , the maximum value of the ground settlement will drop suddenly, and at this time, the design and construction of the tunnel will take great risks, and the working condition with such a small distance should be avoided in design.

[0064] When the net distance is greater than , as the net distance increases, the maximum value of the ground settlement gradually decreases.

[0065] When the two tunnels have a small distance, as the angle increases, the maximum value of the ground settlement decreases rapidly, and in the area where the net distance is 9 - 15m, it is not very sensitive to the change of the layout angle.

[0066] When the net distance is Within this range, the maximum surface settlement is particularly sensitive to changes in the layout angle, and it is advisable to avoid changing the layout angle of the two tunnels in this area as much as possible.

[0067] When the net spacing is less than D, the maximum surface settlement is sensitive to the angle. As the net spacing increases, the influence of the angle on the two tunnels gradually decreases.

[0068] In the range of 40° - 60° for the angle, the mutual influence between the double - hole tunnels is relatively large, especially for small - spacing double - hole tunnels.

[0069] If the net spacing of the two tunnels is fixed, as the angle between the two tunnels decreases, the maximum settlement will gradually increase, but the range of settlement influence is small. Therefore, more monitoring points can be set within a small range, and the detection frequency can be increased.

[0070] Correspondingly, if the angle of the two tunnels remains unchanged, as the net spacing increases, the settlement will decrease accordingly, but the range affected by construction is wide, and more monitoring points need to be set. The density of monitoring point settings and the detection frequency can also be reduced accordingly.

[0071] When the two tunnels have two factors: a relatively small net spacing and an angle between the two tunnels between 40 - 60, not only multiple monitoring points need to be set within a small range, but also the detection frequency needs to be increased.

[0072] As Figure 1 shown, for a certain urban subway interval tunnel, the first line and the second line adopt an overlapping layout method and are constructed by the shield method. The second tunnel is located below. The main soil layer passed through in the overlapping section is the sandy pebble layer, with a buried depth of 21.5 - 23.7m. The groundwater mainly consists of interlayer phreatic water and confined water. The first tunnel is located above, mainly passing through the silty clay layer. The buried depth of the first tunnel is 13.8 - 15.3m. The groundwater mainly consists of phreatic water and interlayer phreatic water. The vertical distance between the overlapping section tunnels is 1.95 - 3.3m.

[0073] A total of 36 settlement monitoring points are arranged on the surface of the completely overlapping section of the shield interval. A total of 18 monitoring points are arranged in the section where the first line passes through the silty clay in the overlapping section, and a total of 18 monitoring points are arranged in the section where the second line passes through the sandy pebble in the overlapping section. The monitoring accuracy is 1.0mm.

[0074] A total of 6 monitoring sections are set in the overlapping section. From Figure 1 the right side to the left side are the first monitoring section, the second monitoring section, the third monitoring section, the fourth monitoring section, the fifth monitoring section, and the sixth monitoring section.

[0075] The first monitoring section is provided with four monitoring points, including the first monitoring point DB1 - 1 to DB - 1 - 4 of the first monitoring section. Figure 1Only the first monitoring point DB1-1 and the fourth monitoring point DB-1-4 of the first monitoring section are marked.

[0076] The second monitoring section is provided with twelve monitoring points, as Figure 1 and Figure 7 shown, including the first monitoring point DB2-1 to DB2-12 of the second monitoring section. Figure 1 Only the first monitoring point DB2-1 and the twelfth monitoring point DB2-12 of the second monitoring section are marked.

[0077] The third monitoring section is provided with two monitoring points, as Figure 1 and Figure 8 shown, including the first monitoring point DB3-1 to the second monitoring point DB3-2 of the third monitoring section.

[0078] The fourth monitoring section is provided with fourteen monitoring points, as Figure 1 and Figure 9 shown, including the first monitoring point DB4-1 to DB4-14 of the fourth monitoring section. Figure 1 Only the first monitoring point DB4-1 and the fourteenth monitoring point DB4-14 of the fourth monitoring section are marked.

[0079] The fifth monitoring section is provided with two monitoring points, as Figure 1 and Figure 10 shown, including the first monitoring point DB5-1 and the second monitoring point DB5-2 of the fifth monitoring section.

[0080] The sixth monitoring section is provided with two monitoring points, including the first monitoring point DB6-1 and the second monitoring point DB6-2 of the sixth monitoring section.

[0081] For example, in the first monitoring section, the angle between the two tunnels is 0, and the final settlement caused by construction is relatively large. However, the span of the up-and-down arrangement is smaller than that of the left-and-right arrangement, the affected range by construction is smaller, and the net distance between the two tunnels is relatively large. In addition, the first monitoring section is located in a cultural relics protection area where it is not allowed to set up detection points. Therefore, two monitoring points are set in this monitoring section, and the detection frequency is appropriately increased during monitoring.

[0082] In the fourth monitoring section, the angle between the two tunnels is in a relatively sensitive range, and the net distance between the two tunnels is small. Therefore, several more monitoring points need to be set in the fourth monitoring section. In the present invention, 14 monitoring points are set, and the detection frequency should be increased.

[0083] For the monitoring points in the same monitoring section, the buried depth is the same.

[0084] The benchmark point must be buried outside the construction impact range (50m) and in the stratum below the depth of soil settlement caused by the construction. Figure 3 As shown, the working reference points adopt cement observation piers with forced centering, with no less than 3 in each survey area to facilitate mutual verification.

[0085] In the present invention, the reference point is a standard level point with a known elevation. During monitoring, the standard elevation of each monitoring point can be obtained by measuring the elevation difference between each monitoring point and the level point (base point), and then compared with the elevation measured last time, and the difference is the settlement value of the measuring point.

[0086] Figure 2 FIG. 2 shows a schematic diagram of the buried reference points of the monitoring of the present invention. Figure 2 As shown, the method of burying the benchmark point includes: using a drilling machine to drill a Φ200mm borehole 105, and inserting a protective pipe 101 after the hole is completely cleaned. An outer pipe 102 and a benchmark rod 104 are arranged in the borehole 105. Clay is backfilled between the walls of the protective pipe 101 and the outer pipe 102. A benchmark point protection base 106 and a benchmark rod 104 are placed in the protective pipe 101. The protection base 106 is cast with cement. The top is made into a spherical shape, and a protective cover for the measuring point is prepared.

[0087] The effectiveness of monitoring the surface settlement of the overlapping section of the overlapping tunnel is directly related to the selected monitoring method and the layout of the measuring points. The monitoring work is based on the premise of meeting on-site safety management and monitoring. The location and number of points should be considered comprehensively in combination with geological conditions, stratum properties, construction technology, surface surrounding environment and monitoring costs. The location of the surface monitoring point should first ensure that it can well reflect the deformation characteristics of the surface, and it should be convenient for instrument observation, and it should also try to avoid damage to the monitoring point by external factors.

[0088] Therefore, the standard method and shallow point setting method should be adopted for the buried monitoring points. The monitoring points are used to collect the settlement data of surface settlement.

[0089] Standard burial method: First, drill a Φ100mm hole in the ground and drive in a Φ22mm threaded steel bar with the top ground into an elliptical shape. Then, fill fine sand around the marking steel bar and compact it. Finally, put an iron cover on the top of the monitoring point for protection. For areas where cavities are detected in advance and where collapse occurs during construction, the standard method is used to bury the surface settlement observation point.

[0090] The method for setting points in the shallow layer is as follows: first, use an impact drill to drill a hole about 20 cm deep and 12 cm in diameter on the ground, then place a φ8 mm round steel with a convex spherical surface on the top into the hole, and fill the gap with an anchor.

[0091] The surface settlement control index is the deformation control index, and the monitoring control standard is as follows: the maximum allowable settlement value is 30 mm, the maximum allowable deformation rate is 4 mm / d, and the surface heave control value is 10 mm.

[0092] The monitoring points for road and surface settlement should be buried flat to prevent the unevenness from affecting the passage of personnel and vehicles. At the same time, the monitoring points should be firmly buried and clearly marked for easy preservation.

[0093] After setting up the monitoring points, the present invention starts to monitor the surface settlement during the construction process. The first launched tunnel is the second tunnel 2, and the later launched tunnel is the first tunnel 1. The first distance is the distance between the tunneling face of the shield and the monitoring section in front of the shield. The second distance is the distance between the tunneling face of the shield and the monitoring section behind the shield.

[0094] First, monitor the surface settlement caused by the first launched tunnel during the shield tunneling process and collect the relevant data of the surface settlement.

[0095] Second, monitor the secondary vibration influence caused by the shield tunneling of the later launched tunnel and collect the relevant data of the surface settlement.

[0096] Adjust the collection frequency of the settlement data based on the change of the first and / or second distance between the tunneling face and the monitoring section.

[0097] Specifically, when the first and / or second distance between the tunneling face and the monitoring section is not greater than the first threshold, the collection frequency of the settlement data of this monitoring section is the first frequency. The first threshold is 20 m, and the first frequency is once a day.

[0098] When the first and / or second distance between the tunneling face and the monitoring section is greater than the first threshold and not greater than the second threshold, the collection frequency of the settlement data of this monitoring section is the second frequency. The second threshold is 50 m, and the second frequency is once every two days.

[0099] When the first and / or second distance between the tunneling face and the monitoring section is greater than the second threshold, the collection frequency of the settlement data of this monitoring section is the third frequency. The third frequency is once a week.

[0100] That is, as the tunneling face of the shield changes, the collection frequency of the settlement data of each monitoring section also changes, and the collection frequencies of the monitoring points of each monitoring section are different. Compared with the method of collecting settlement data at the same frequency for each monitoring point in the prior art, the adjustment method of the change of the collection frequency of the settlement data of the present invention can reduce the collection and storage of a large amount of invalid data.

[0101] Preferably, analyze the settlement situation based on the data. When the surface settlement is stable, adjust the collection frequency of the settlement data to the fourth frequency. The fourth frequency is once a month.

[0102] The conditions for surface subsidence to become stable include at least:

[0103] The speed of road and surface subsidence has shown a clear trend of slowing down;

[0104] The convergence rate of road and surface settlement is less than 0.01-0.04 mm / day;

[0105] The convergence amount reaches 80% or more of the total convergence amount.

[0106] In the event of abnormal surface settlement, the frequency of settlement data collection increases.

[0107] Preferably, each time on-site monitoring work is implemented, an on-site safety inspection is also carried out, and it is ensured that the inspection is carried out once a day. The inspection frequency should be increased in special circumstances.

[0108] The raw data obtained by field measurement has a certain degree of discreteness, including the influence of accidental errors, so the present invention uses a discrete graph of the settlement-time curve for processing. After collecting the data of surface settlement, the present invention analyzes the data based on the settlement-time distribution fitting curve of the surface settlement and predicts the maximum settlement.

[0109] According to the measured road and surface subsidence values, the present invention determines whether the road and surface subsidence exceeds the safety control standard and the reliability of the adopted engineering measures. The stage deformation rate and deformation amount are compared with the control standard to determine the early warning status of the monitoring point. If the data shows that the warning standard is reached and the analysis confirms that there is an abnormal situation, the detection frequency should be increased and relevant processing should be done in time.

[0110] The present invention can determine the cause of surface subsidence by processing and analyzing data in combination with specific construction conditions, and take relevant measures to reduce surface subsidence. In addition, the present invention can also achieve full-process monitoring, further enhancing the effect of information-based construction.

[0111] Specifically, the monitoring data of the present invention is processed and analyzed as follows.

[0112] Monitor the surface settlement caused by the shield tunneling process in the first starting tunnel, collect relevant data on surface settlement and analyze it. The settlement-time distribution fitting curve is as follows: Figure 5 shown.

[0113] The shield machine of the first tunnel is carrying out preparatory work before construction. At the same time, the second tunnel has been constructed to the 348th ring. At this time, the surface deformation of the overlapping section caused by the construction of the second-line shield machine has basically ended. The first to sixth monitoring sections are continuously monitored until the settlement is basically stable.

[0114] like Figure 5As shown, the maximum settlement at the second monitoring section is 5.93 mm, which is slightly smaller than that of other monitoring sections. This is due to the fact that the second monitoring section is in the shield starting stage, with a slow shield propulsion speed and good reinforcement effect at the starting end.

[0115] It can be seen from Figure 5 that the settlement curves at the first and second monitoring sections are asymmetrically distributed along the tunnel center. The maximum settlement at each monitoring section occurs on the tunnel center line and gradually decreases laterally along the tunnel. There is a small uplift on the ground surface in the area far from the axis, with an average of less than 2 mm.

[0116] According to the above monitoring results, the settlement values at the first and second monitoring sections with silty clay overburden are generally smaller than those at the third, fourth, fifth, and sixth monitoring sections with sandy cobble stratum overburden. The average settlement values at the first and second monitoring sections are about 7 mm. The average settlement values at the other four monitoring sections are about 12 mm. Under the same construction conditions, the ground surface settlement with silty clay overburden is slightly smaller than that with sandy cobble layer overburden.

[0117] According to Figure 5 the monitoring results, when the soil layers and overburden properties traversed by the third, fifth, and sixth monitoring sections are basically the same, the average settlement increases in turn, which is due to the continuous decrease of the tunnel burial depth along the tunnel driving direction.

[0118] It can be seen from Figure 5 that the settlement monitoring points 43 and 44 at the fourth monitoring section fluctuate greatly, possibly due to construction or damage to the monitoring points.

[0119] The overall monitoring results show that the maximum settlement in the overlapping section appears at the fourth monitoring section, with a maximum settlement of 19.08 mm. Within the design allowable range, the settlement amounts at other monitoring sections are all less than 15.00 mm. During the on-site inspection, the shield construction parameters are appropriate, the shield attitude is good, and there is no need for large-scale rectification. The overall construction of the lower-line tunnel in the overlapping section is in good condition.

[0120] Monitor the secondary vibration impact caused during the shield process of the starting tunnel, collect relevant data on ground surface settlement, and the fitting curves of its settlement-time distribution are as shown in Figure 6 and Figure 7 shown.

[0121] The construction of the first tunnel 1 caused secondary disturbance to the stratum, resulting in secondary settlement of the ground surface. Then, the six monitoring sections from the first to the sixth were monitored until the ground surface settlement was basically stable.

[0122] According to Figure 6 and Figure 7It can be seen that the first tunnel construction causes the ground surface to first bulge and then subside. This is because the reinforcement effect of the second tunnel is good, and the extrusion of the soil in front of the shield before reaching the monitoring point causes the ground surface to have an upward bulging trend. When the shield body passes through the monitoring point, the surrounding soil loses the support of the shield shell and is replaced by the support of the slurry that has not solidified or has not fully solidified, resulting in a subsidence trend on the ground surface. Secondary grouting is carried out in a timely manner after the shield passes through, and the ground surface subsidence gradually becomes stable. From Figure 2 and Figure 3 it can be known that the maximum subsidence value of the first monitoring section is 8.45 mm, and the maximum subsidence value of the second monitoring section is 12.35 mm, and the control effect on the ground surface subsidence is good.

[0123] As shown in 8 and Figure 9 indicates, the subsidence law of the third monitoring section is different from that of the second monitoring section. When the first tunnel is constructed, the third monitoring section not only has no bulging trend, but also the subsidence has already started when the shield reaches the monitoring point. During the shield propulsion process, the subsidence amount of the third monitoring section continuously increases, the subsidence rate is relatively large, and the ground surface subsidence obviously has a tendency to exceed the specified value of 30 mm. On October 15th, the grouting slurry was synchronously replaced with cement-sodium silicate slurry, and the area with too large subsidence rate was timely grouted twice with double-fluid slurry, basically controlling the problem of too large subsidence rate, but the maximum subsidence amount of the third monitoring section still reached 34.26 mm.

[0124] The ground surface subsidence amount of the third monitoring section exceeds that of the second monitoring section by a large margin. After summarizing and analyzing, it is concluded that the reason for the excessive subsidence of the third monitoring section is that the interlayer soil between the first and second tunnels where the third monitoring section is located has not been reinforced, resulting in excessive subsidence. The second monitoring section has not been reinforced for the interlayer soil and has not shown large subsidence because the soil layer passed through by the second monitoring section is mainly silty clay layer, and the interlayer soil reinforcement is not required to pass through the silty clay layer. However, the soil layer passed through by the third monitoring section is mainly sandy cobble layer, and the interlayer soil reinforcement is required for the sandy cobble layer, and the interlayer soil of the sandy cobble layer soil to be passed through should be reinforced.

[0125] From Figure 9 it can be known that the maximum subsidence amount of the fourth monitoring section is 23.22 mm. Relatively speaking, the control effect of the ground surface subsidence is good, and there is a trend of first bulging and then subsiding during the propulsion, which is similar to the subsidence law of the second monitoring section. The control effect of the ground surface subsidence of the fourth monitoring section is better than that of the third monitoring section because of the reinforcement of the interlayer soil between the upper and lower tunnels. It can be seen that when the soil layer passed through by the shield is silty clay layer, the interlayer soil does not need to be reinforced, and when the soil layer passed through by the shield is sandy cobble layer, the interlayer soil needs to be reinforced.

[0126] From Figure 10It can be seen that during the shield tunneling process, the ground surface has a tendency to bulge first. However, from October 26th to October 28th, the ground settlement rate was too large, and the maximum settlement rate reached 4 mm / day. Since October 29th, the ground settlement rate has decreased and the ground settlement has tended to be stable. Through on-site investigation, it was found that during the period from October 26th to October 28th, due to a shield failure, the tunneling stopped, and the shield resumed normal tunneling on October 29th. Before the shield tunneling stopped, although the amount of soil excavation was reduced and the tunneling continued to make the soil pressure in the soil chamber slightly greater than the set soil pressure, the downtime was relatively long and no other measures were taken to prevent the shield from retreating, resulting in an excessive ground settlement rate during the downtime.

[0127] It can be seen from Figure 11 that the maximum settlement of the ground surface at the sixth monitoring section is 17.81 mm. Relatively speaking, the ground settlement control effect is good, and there is a tendency of first bulging and then settlement during the tunneling, which is similar to the settlement law of the second and fourth monitoring sections.

[0128] It can be seen from the settlement diagrams of the second, fourth, and sixth monitoring sections that the advancing of the trailing shield in the overlapping section has a tendency of first bulging and then settlement on the ground surface. Under the condition that various settlement control measures have good effects, the post-settlement value is not large and is within the allowable range of ground settlement.

[0129] It can be obtained from the settlement diagrams of the ground surface of the second, fourth, and sixth monitoring sections that the ground settlement caused by the advancing of the lower tunnel accounts for 76.65% of the total settlement, and the ground settlement caused by the advancing of the upper tunnel accounts for 23.35% of the total settlement. It can be obtained from the settlement diagrams of the ground surface of the third and fifth monitoring sections that the ground settlement caused by the advancing of the lower tunnel accounts for 34.78% of the total settlement, and the ground settlement caused by the advancing of the upper tunnel accounts for 65.22% of the total settlement.

[0130] It can be seen that when the ground settlement control of the upper tunnel is good, the main reason for the ground settlement is the advancing of the lower tunnel. When the ground settlement control of the upper tunnel is not ideal, the main reason for the ground settlement is the advancing of the upper tunnel. Therefore, during the advancing of the trailing shield in the overlapping tunnel, the ground settlement control measures should be strengthened to minimize the secondary ground disturbance caused by the advancing of the trailing shield.

[0131] It should be noted that the above specific embodiments are exemplary. Those skilled in the art can come up with various solutions inspired by the disclosure of the present invention, and these solutions also fall within the scope of the disclosure of the present invention and within the protection scope of the present invention. Those skilled in the art should understand that the description and drawings of the present invention are illustrative and do not constitute a limitation on the claims. The protection scope of the present invention is defined by the claims and their equivalents. The description of the present invention contains multiple inventive concepts. Expressions such as "preferably", "according to a preferred embodiment" or "optionally" all indicate that the corresponding paragraphs disclose an independent inventive concept. The applicant reserves the right to file divisional applications based on each inventive concept.

Claims

1. A method for adjusting the settlement data collection frequency of the complete overlapping section of an overlapping tunnel, characterized in that The method at least comprises: Monitor the ground settlement caused by the shield tunneling process in the first launch tunnel and collect relevant data on the ground settlement; Monitor the secondary vibration caused by the shield tunneling process of the rear start tunnel and collect relevant data on surface settlement; The collection frequency of settlement data is adjusted based on the change of the first and / or second distance between the excavation face and the monitoring section, wherein the first distance is the distance between the excavation face of the shield machine and the monitoring section located in front of the shield machine; the second distance is the distance between the excavation face of the shield machine and the monitoring section located behind the shield machine; wherein, when the first and / or second distance between the excavation face and the monitoring section is not greater than a first threshold value, the collection frequency of settlement data is the first frequency; when the first and / or second distance between the excavation face and the monitoring section is greater than the first threshold value and not greater than the second threshold value, the collection frequency of settlement data is the second frequency; when the first and / or second distance between the excavation face and the monitoring section is greater than the second threshold value, the collection frequency of settlement data is the third frequency; The maximum settlement is predicted based on the settlement-time distribution fitting curve of the surface settlement, and interlayer soil reinforcement is carried out at the location with large settlement; The number and distribution range of monitoring points set in the monitoring section are determined based on the clear spacing and / or angle between the stacked tunnels corresponding to the monitoring section; wherein, when the angle between two stacked tunnels is in the range of 40°~60°, if the clear spacing between the two tunnels is fixed, as the angle between the two stacked tunnels decreases, more monitoring points are set within the range affected by settlement, and the detection frequency is increased.

2. The method for adjusting the settlement data collection frequency of the complete overlapping section of an overlapping tunnel according to claim 1, characterized in that The method further comprises: When the surface settlement is stable, the collection frequency of the settlement data is adjusted to the fourth frequency.

3. The method for adjusting the settlement data collection frequency of the complete overlapping section of an overlapping tunnel according to claim 2, characterized in that The method further comprises: In the event of abnormal surface settlement, the frequency of settlement data collection increases.

4. The method for adjusting the settlement data collection frequency of the complete overlapping section of an overlapping tunnel according to claim 1, characterized in that The method further comprises: When the angle between the two overlapping tunnels is in the range of 40° to 60°, if the angle between the two tunnels remains unchanged, more monitoring points are set as the net spacing increases, and the density of the monitoring point settings and the detection frequency are reduced accordingly.

5. The method for adjusting the settlement data collection frequency of the complete overlapping section of an overlapping tunnel according to claim 1, characterized in that The method further comprises: In the first monitoring section where the angle between the two overlapping tunnels is 0°, two or four monitoring points are arranged in the first monitoring section.

6. The method for adjusting the settlement data collection frequency of the complete overlapping section of an overlapping tunnel according to claim 1, characterized in that The first threshold is 20m, and the first frequency is once a day; The second threshold is 50m, and the second frequency is once every two days; The third frequency is once a week, The fourth frequency is once a month.

7. The method for adjusting the settlement data collection frequency of the complete overlapping section of an overlapping tunnel according to claim 1, characterized in that The conditions for the surface settlement to be stable include at least: The speed of road and surface subsidence has shown a clear trend of slowing down; The convergence rate of road and surface settlement is less than 0.01~0.04mm / day; The convergence amount reaches 80% or more of the total convergence amount.

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