CN114413839A

CN114413839A - Device and method for monitoring complete overlapping section of up-down overlapping type tunnel

Info

Publication number: CN114413839A
Application number: CN202210327480.7A
Authority: CN
Inventors: 江华; 沈晴云; 江玉生; 朱家辰
Original assignee: China University of Mining and Technology Beijing CUMTB
Current assignee: China University of Mining and Technology Beijing CUMTB
Priority date: 2022-03-31
Filing date: 2022-03-31
Publication date: 2022-04-29
Anticipated expiration: 2042-03-31
Also published as: CN115655207A; CN115235417A; CN114413839B; CN115235417B

Abstract

The invention relates to a device and a method for monitoring a complete overlap section of an up-and-down overlap type tunnel, wherein the method at least comprises the following steps: selecting at least one vertical surface vertical to the axis of the stacked tunnel as a monitoring section of the stacked tunnel based on the stacking degree between the stacked tunnels, determining the number of monitoring points arranged on the monitoring section based on the stacking degree of the stacked tunnel corresponding to the monitoring section, and processing and analyzing settlement data based on the settlement data sent by the monitoring points. Compared with the method of burying the monitoring points for multiple times, the method only needs to bury the monitoring points once, collects the transverse settlement data from one monitoring section to another monitoring section and the longitudinal monitoring data of the monitoring points arranged along the monitoring sections, can monitor the ground surface settlement caused by starting tunnels successively, and forms a three-dimensional monitoring mode. The invention can judge the reason causing the surface subsidence by processing and analyzing the data and combining the concrete construction condition, and adopt the relevant measures to reduce the surface subsidence.

Description

Device and method for monitoring complete overlapping section of up-down overlapping type tunnel

Technical Field

The invention relates to the technical field of stacked tunnel construction, in particular to a device and a method for monitoring a complete stacked section of an up-down stacked tunnel.

Background

The disturbance of the subway tunnel construction to the ground surface is inevitable, the disturbance of the shield construction method to the ground surface is relatively small in various construction methods, the subway section construction is mostly in a relatively busy city and densely populated area, and the monitoring of the shield tunnel section for feedback construction is particularly important because the deformation of the ground surface is larger than a deformation critical value and can greatly affect peripheral high-rise buildings, roads, underground pipelines and the like.

With the development and utilization of underground space, more and more tunnels are arranged in an up-down stacking manner, the influence range and size of the shield on the upper earth surface in the up-down stacking construction are completely different from those of normal parallel tunnels, and no experience reference exists.

In the shield propulsion process, the upper building or people can be influenced by the vibration of the foundation or the ground surface caused by the vibration and the secondary vibration generated by the vibration, and particularly the structural safety of ancient and old buildings is influenced.

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

For example, chinese patent document CN 103277110A discloses a construction method of a stacked shield tunnel, the construction steps include: tunneling construction of a downlink shield tunnel, wherein a tunnel structure adopts reinforced segments; the downlink tunnel is grouted into the soil body clamped between the uplink tunnel and the downlink tunnel through a grouting pipe in the secondary grouting hole; before the construction of the uplink tunnel, a trolley supporting system is arranged in the downlink tunnel to protect the downlink tunnel; performing tunneling construction of an uplink shield tunnel, wherein a downlink tunnel supporting trolley keeps following with the tunneling of the uplink tunnel in a synchronous manner in the construction process; and the ascending tunnel is grouted into the soil body clamped between the ascending tunnel and the descending tunnel through the grouting pipe in the secondary grouting hole.

For example, the chinese patent document CN 105332710A discloses a construction method of an up-and-down overlapped tunnel suitable for a long distance with a small clear space under weak geology, the upper and lower overlapped tunnels comprise an upper tunnel and a lower tunnel which have the same tunnel diameter and the same tunnel length, the upper tunnel and the lower tunnel are respectively formed into tunnel structures by duct pieces, the vertical clear distance between the upper tunnel and the lower tunnel is less than 0.7D (shield diameter), the tunnel length is more than 1000m, the shield construction method is that after the tunnel is dug out according to the conventional shield construction method, the shield high-altitude starting platform, the deep hole grouting reinforcement of the interlayer soil body of the upper tunnel and the lower tunnel, the reinforcement of the support steel ring of the tunnel is dug out, the shield high-altitude receiving platform and other measures are adopted to reduce the influence of the shield construction of the upper tunnel on the formed tunnel and the secondary superposition effect of the subsidence of the overlapped tunnel, and ensure the deformation of the tunnel and the controllable ground subsidence.

None of the above prior art relates to the problem of burying monitoring points of a complete overlap section, and therefore does not solve the problems proposed by the present invention: how to monitor and reduce the vibration influence of the stacked tunnel construction.

Furthermore, on the one hand, due to the differences in understanding to the person skilled in the art; on the other hand, since the applicant has studied a great deal of literature and patents when making the present invention, but the disclosure is not limited thereto and the details and contents thereof are not listed in detail, it is by no means the present invention has these prior art features, but the present invention has all the features of the prior art, and the applicant reserves the right to increase the related prior art in the background.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a method for monitoring the complete stacking section of an up-down stacking type tunnel, which comprises the steps of selecting at least one vertical surface vertical to the axis of the stacking type tunnel as a monitoring section of the stacking type tunnel based on the stacking degree between the stacking type tunnels, determining the number of monitoring points arranged on the monitoring section based on the net spacing and/or the angle between the stacking type tunnels corresponding to the monitoring section, and carrying out settlement data processing and analysis based on settlement data sent by the monitoring points.

The method monitors the influence of the ground surface settlement caused in the construction process of the stacked tunnel in the whole process, can collect the ground surface settlement data caused by the tunnel which is started first, and can also monitor the influence of the tunnel which is started later on the tunnel which is started first and the ground surface settlement. Through the selection of the monitoring sections and the arrangement of the monitoring points, the transverse settlement data from one monitoring section to another monitoring section and the longitudinal monitoring data of the monitoring points arranged along the monitoring sections can be collected, so that the three-dimensional monitoring is formed, and the detection result is more accurate.

Preferably, the degree of overlap is related to the horizontal distance, the vertical distance and the radius of the tunnel axis between at least two tunnels,

wherein S represents the stacking degree, L represents the horizontal distance of the tunnel axis, H represents the vertical distance of the tunnel axis,

the radius of the first tunnel is indicated,

representing the radius of the second tunnel.

Preferably, the net spacing and/or angle between the stacked tunnels is related to a maximum settlement value, and the number and distribution range of the monitoring points are set based on the related association of the net spacing and/or angle between the tunnels and the maximum settlement value.

Preferably, the method further comprises: adjusting the frequency of settlement data collection based on changes in the first and/or second distances of the excavation face from the monitored face.

Preferably, when the first and/or second distance between the heading face and the monitoring section is not greater than a first threshold value, the collection frequency of the settlement data is a first frequency; when the first and/or second distance between the tunneling surface and the monitoring section is larger than a first threshold and not larger than a second threshold, the collection frequency of the settlement data is a second frequency; and when the first and/or second distance between the heading face and the monitoring section is larger than a second threshold value, the collection frequency of the settlement data is a third frequency.

Preferably, the method further comprises: and in the case of stable ground surface settlement, adjusting the collection frequency of settlement data to be a fourth frequency.

Preferably, the method further comprises: in the case where the surface subsidence is abnormal, the frequency of collection of subsidence data increases.

The data collection frequency of each monitoring section is dynamically adjusted based on the change of the tunneling surface, the effective utilization of data is improved, and the collection of data with small data analysis effect is reduced.

Preferably, the method further comprises: and predicting the maximum sedimentation amount based on a sedimentation-time distribution fitting curve of the surface sedimentation.

Preferably, the conditions for achieving stability of the surface subsidence at least comprise:

the sedimentation speed of roads and earth surfaces has a remarkably slowing trend;

the settlement convergence speed of the road and the ground surface is less than 0.01-0.04 mm/day;

the amount of convergence is 80% or more of the total amount of convergence.

By predicting the maximum settlement, the method can reinforce the part with larger settlement so as to ensure the normal operation of the shield construction process and prevent larger influence on surrounding buildings. The invention can monitor in the whole construction process, and avoids larger construction hidden danger in the construction process with smaller capital investment.

The invention also provides a device for monitoring the complete stacking section of the up-down stacking type tunnel, which at least comprises a plurality of monitoring units, wherein the monitoring units form monitoring points for monitoring the ground surface settlement after being buried underground, the monitoring section where the monitoring points are located is at least one vertical surface which is selected based on the stacking degree between the stacking type tunnels and is vertical to the axis of the stacking type tunnel, and the number of the monitoring points in the monitoring section is determined based on the net spacing and/or the angle between the stacking type tunnels corresponding to the monitoring section. Wherein the monitoring unit is a sensor capable of monitoring the ground surface settlement.

The monitoring device can monitor the ground surface settlement condition caused by starting a tunnel successively only by burying a monitoring point once to form three-dimensional monitoring, can judge the reason causing the ground surface settlement by processing and analyzing data and combining specific construction conditions, adopts related measures to reduce the ground surface settlement, can realize whole-process monitoring, further enhances the effect of information construction, provides a communication channel for construction and supervision units, evaluates the safety condition of a soil body, and provides reasonable construction suggestion measures to ensure the safety construction of subway projects.

Drawings

FIG. 1 is a schematic diagram of the arrangement of the ground surface settlement monitoring points of the stacking segment provided by the invention;

FIG. 2 is a schematic diagram illustrating the embedding of datum points provided by the present invention;

FIG. 3 is an enlarged schematic view of a monitoring operating base point provided by the present invention;

FIG. 4 is a schematic diagram of the fold-down degree dividing elements provided by the present invention;

FIG. 5 is a schematic illustration of a sedimentation curve for each monitoring section provided by the present invention;

FIG. 6 is a schematic longitudinal subsidence view of a section D1 in the first tunnel construction provided by the invention;

FIG. 7 is a schematic longitudinal subsidence view of a section D2 in the first tunnel construction provided by the invention;

FIG. 8 is a schematic longitudinal subsidence view of a section D3 in the first tunnel construction provided by the invention;

FIG. 9 is a schematic longitudinal subsidence view of a cross section D4 in the first tunnel construction provided by the invention;

FIG. 10 is a schematic longitudinal subsidence view of a cross section D5 in the first tunnel construction provided by the invention;

fig. 11 is a schematic longitudinal subsidence view of a section D6 in the first tunnel construction provided by the present invention.

List of reference numerals

1: a first tunnel; 2: a second tunnel; 101: protecting the tube; 102: an outer tube; 103: a hanging clip; 104: a marker post; 105: drilling; 106: a base point base; DB 1-1: a first monitoring point of the first monitoring section; DB 1-4: a fourth monitoring point of the first monitoring section; DB 2-1: a first monitoring point of a second monitoring section; DB 2-12: a twelfth monitoring point of the second monitoring section; DB 3-1: a first monitoring point of a third monitoring section; DB 3-2: a second monitoring point of the third monitoring section; DB 4-1: a fourth monitoring section first monitoring point; DB 4-14: a fourteenth monitoring point of the fourth monitoring section; DB 5-1: a first monitoring point of a fifth monitoring section; DB 5-2: a second monitoring point of the fifth monitoring section; DB 6-1: sixthly, monitoring a first monitoring point of the section; DB 6-2: and a sixth monitoring section second monitoring point.

Detailed Description

The following detailed description is made with reference to the accompanying drawings.

Based on the defects of the prior art, the invention provides a method and a device for monitoring a complete overlap section of an up-and-down overlap type tunnel. The invention also can provide a dynamic three-dimensional monitoring method and a device for the complete overlapping section of the overlapping tunnel.

The invention discloses a method for monitoring a complete overlapping section of an up-down overlapping type tunnel, which at least comprises the following steps: selecting at least one vertical surface vertical to the axis of the stacked tunnel as a monitoring section of the stacked tunnel based on the stacking degree between the stacked tunnels, determining the number of monitoring points arranged on the monitoring section based on the net spacing and/or the angle between the stacked tunnels corresponding to the monitoring section, and performing settlement data processing and analysis based on settlement data sent by the monitoring points.

The monitoring section where the monitoring point is located is determined according to the actual engineering requirements.

The fold drop is related to the horizontal distance, the vertical distance and the radius of the tunnel axis between at least two tunnels. As shown in figure 4 of the drawings,

the radius of the first tunnel is indicated,

representing the radius of the second tunnel.

The number of monitoring points arranged for monitoring the section is determined based on the net spacing and/or the angle between the stacked tunnels.

The net spacing and/or angle between stacked tunnels is related to the maximum settlement value. The number and distribution range of the monitoring points is thus set based on the correlation of the net spacing and/or angle between the tunnels with the maximum sedimentation value.

Specifically, the number of monitoring points of the monitoring section is set according to the following net spacing and/or angle conditions. In the present invention, the tunnel diameter is set to D,

is 2 m. The clear distance is the length of the connecting line of the centers of the two tunnels in the cross section of the tunnel minus the length of one tunnel diameter.

When the shallow-buried double-hole tunnel is horizontally arranged, the mutual influence between the two tunnels is particularly large when the net distance between the two tunnels is small.

When the net spacing is less than

During the time, the earth's surface subsides the maximum value and can suddenly descend a lot, and the design construction in tunnel this moment will emerge very big risk, should avoid designing so booth apart from the operating mode.

When the net spacing is greater than

In time, the maximum value of surface subsidence gradually decreases as the net spacing increases.

When the two tunnels are at a small interval, the maximum value of the ground surface settlement is rapidly reduced along with the increase of the angle, and the section of the region with the net interval of 9-15 m is not sensitive to the change of the arrangement angle.

At a net spacing of

~

In this interval, the maximum value of the ground surface settlement is particularly sensitive to the change of the arrangement angle, and the change of the arrangement angle of the two tunnels in the area is avoided as much as possible.

When the net spacing is less than D, the maximum value of surface subsidence is relatively sensitive to angle. As the net spacing increases, the angle has a decreasing effect on the interaction of the two tunnels.

The mutual influence between the double-hole tunnels is large in the range of the angle of 40-60 degrees, and particularly the double-hole tunnels with small spacing.

If the net distance between the two tunnels is fixed, the maximum sedimentation value is gradually increased along with the reduction of the angle between the two tunnels, but the sedimentation influence range is smaller, so that more monitoring points can be arranged in a small range, and the detection frequency is increased.

Correspondingly, if the angles of the two tunnels are unchanged, the settlement can be correspondingly reduced along with the increase of the net distance, but the range influenced by construction is wide, more monitoring points need to be arranged, and the density and the detection frequency of the monitoring points can be correspondingly reduced.

When two tunnels simultaneously have two factors of small clear distance and angle between 40 and 60, a plurality of monitoring points are not needed to be arranged in a small range, and the detection frequency needs to be increased.

As shown in fig. 1, the first line and the second line of the tunnel in a certain city subway section are constructed by a shield method in a stacking-falling arrangement mode. The second tunnel is located below, the superposed section penetrating soil layer is mainly a sand-gravel layer with the burial depth of 21.5-23.7 m, and the underground water is mainly interlayer diving and confined water. The first tunnel is positioned above and mainly penetrates through the soil layer to form a silty clay layer. The buried depth of the first tunnel is 13.8-15.3 m. Groundwater is mainly diving and interlaminar diving. The vertical distance of the tunnel at the overlap section is 1.95-3.3 m.

36 settlement monitoring points are arranged on the ground surface of the completely-superposed section in the shield region. The first line stacking section passes through the silty clay section and is provided with 18 monitoring points, the second line stacking section passes through the sand and pebble section and is provided with 18 monitoring points, and the monitoring precision is 1.0 mm.

The stacking section is provided with 6 monitoring sections. 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 are arranged in sequence from the right side to the left side of the figure 1.

The first monitoring section is provided with four monitoring points including a first monitoring point DB 1-1-DB-1-4 of the first monitoring section. Only the first monitoring section first monitoring point DB1-1 and the first monitoring section fourth monitoring point DB-1-4 are marked in FIG. 1.

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

The third monitoring section is provided with two monitoring points, as shown in the figures 1 and 8, and comprises a first monitoring point DB3-1 of the third monitoring section and a second monitoring point DB3-2 of the third monitoring section.

The fourth monitoring section is provided with fourteen monitoring points, as shown in figures 1 and 9, and comprises first monitoring points DB 4-1-DB 4-14 of the fourth monitoring section. Only the fourth monitoring section first monitoring point DB4-1 and the fourth monitoring section fourteenth monitoring point DB4-14 are labeled in FIG. 1.

The fifth monitoring section is provided with two monitoring points, as shown in fig. 1 and 10, including a fifth monitoring section first monitoring point DB5-1 and a fifth monitoring section second monitoring point DB 5-2.

The sixth monitoring section is provided with two monitoring points, including a sixth monitoring section first monitoring point DB6-1 and a sixth monitoring section second monitoring point DB 6-2.

For example, in the first monitoring section, the angle between the two tunnels is 0, the final settlement caused by construction is larger, but the vertical arrangement is smaller than the horizontal arrangement, the range influenced by construction is small, and the net distance between the two tunnels is larger. In addition, the first monitoring section is located in the cultural relic protection area, and a detection point is not allowed to be set, so that two monitoring points are arranged on the monitoring section. The monitoring frequency is increased appropriately at the time of monitoring.

In the fourth monitoring section, the angle of the two tunnels is in a sensitive range, and the net distance between the two tunnels is small, so that a plurality of monitoring points are additionally arranged on the fourth monitoring section. The present invention sets 14 monitoring points and the detection frequency is to be increased.

The buried depth of the monitoring points on the same monitoring section is the same.

The reference point is buried outside the construction affected range (50 m), and the reference point is buried in the stratum below the depth of influence of soil settlement caused by construction. As shown in FIG. 3, the working datum points adopt forced centering cement observation piers, and each measurement area is not less than 3 so as to be mutually checked.

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 a reference point (base point), and then the standard elevation is compared with the last measured elevation, and the difference value is the settlement value of the measuring point.

FIG. 2 shows a schematic view of the burying of a monitored datum of the present invention. As shown in fig. 2, the way of embedding the reference points includes: a drill 105 with a diameter of 200mm is drilled and after the hole is completely cleared a protective pipe 101 is laid. An outer tube 102 and a target 104 are disposed within a borehole 105. Clay is backfilled between the walls of the protective pipe 101 and the outer pipe 102. The incorporation of the datum point within the protective tube 101 protects the base 106 and the post 104. The protective base 106 is cast with cement. The top is made into a spherical shape, and a protective cover of the measuring point is made.

The effectiveness of the monitoring work of the ground surface settlement of the stacking section of the stacking tunnel is directly related to the selected monitoring method and the arrangement of the measuring points. The monitoring work is on the premise of meeting site safety management and monitoring, and the distribution positions and quantity are comprehensively considered by combining the factors of geological conditions, stratum properties, construction process, surface surrounding environment, monitoring cost and the like. The position of the earth surface monitoring point should firstly ensure that the deformation characteristic of the earth surface can be well reflected, and the monitoring point is required to be prevented from being damaged by external factors as much as possible for the observation of instruments.

Therefore, the standard method and the shallow layer point setting method are adopted for monitoring point burying. The monitoring points are used for collecting settlement data of the surface settlement.

The standard embedding method comprises the following steps: firstly, a hole with the diameter of 100mm is drilled on the ground, and a threaded reinforcing steel bar with the diameter of 22mm, the top of which is ground into an oval shape, is driven into the hole. Then, fine sand is filled around the mark steel bars for tamping, and finally, an iron cover is arranged on the upper part of the monitoring point for protection. And (3) burying a ground surface settlement observation point in a section where a cavity exists in the ground and collapse occurs in construction by adopting a standard method.

The shallow layer point setting method comprises the following steps: firstly, a hole with the depth of about 20cm and the diameter of 12cm is drilled on the ground by a percussion drill, then a round steel with the diameter of 8mm and the top part provided with a convex spherical surface is put into the hole, and the gap is filled with an anchoring agent.

The ground surface settlement control index is a deformation control index, and the monitoring control standard is as follows: the maximum allowable sedimentation value is 30mm, the maximum allowable deformation rate is 4mm/d, and the ground surface uplift control value is 10 mm.

The road and the ground surface settlement monitoring measuring points are required to be embedded and leveled, so that the situation that personnel and vehicles pass through due to uneven height is prevented, and meanwhile, the monitoring points are embedded and stabilized, clear marks are made, and the storage is convenient.

After the monitoring points are set, the invention starts to monitor the condition of surface subsidence in the construction process. The first originating tunnel is the second tunnel 2 and the second originating tunnel is the first tunnel 1. The first distance is the distance between the tunneling surface of the shield and the monitoring section positioned in front of the shield. The second distance is the distance between the tunneling surface of the shield and the monitoring section behind the shield.

Firstly, monitoring the surface subsidence caused by the initial tunnel in the shield process, and collecting relevant data of the surface subsidence.

Secondly, monitoring secondary vibration influence caused in the process of starting the tunnel shield, and collecting relevant data of surface subsidence.

The frequency of settlement data collection is adjusted based on changes in the first and/or second distances of the heading face from the monitored face.

Specifically, when the first and/or second distance between the heading face and the monitoring section is not larger than a first threshold value, the collection frequency of the settlement data of the monitoring section is a first frequency. The first threshold is 20m and the first frequency is once a day.

And when the first and/or second distance between the heading face and the monitoring section is larger than a first threshold and not larger than a second threshold, the collection frequency of the settlement data of the monitoring section is a second frequency. The second threshold is 50m and the second frequency is once every two days.

And when the first and/or second distance between the heading face and the monitoring section is larger than a second threshold value, the collection frequency of the settlement data of the monitoring section is a third frequency. The third frequency is once per week.

That is, along with the change of the excavation surface of the shield, the collection frequency of the settlement data of each monitoring section is changed, and the collection frequency of the monitoring points of each monitoring section is different. Compared with the mode that each monitoring point collects the settlement data at the same frequency in the prior art, the settlement data collection frequency change adjusting mode can reduce the collection and storage of a large amount of invalid data.

Preferably, the sedimentation is analyzed from the data. And in the case of stable ground surface settlement, adjusting the collection frequency of settlement data to be a fourth frequency. The fourth frequency is once a month.

The conditions for achieving stable surface subsidence at least comprise:

the amount of convergence is 80% or more of the total amount of convergence.

In the case where the surface subsidence is abnormal, the frequency of collection of subsidence data increases.

Preferably, when the field monitoring work is carried out every time, the field safety inspection is carried out at the same time, and the inspection is ensured once every day, and the inspection frequency is increased under special conditions.

The raw data obtained by field measurement has certain discreteness and contains the influence of accidental errors, so the invention selects the discrete graph of the sedimentation-time curve for processing. After the data of the surface subsidence are collected, the invention analyzes the data based on the subsidence-time distribution fitting curve of the surface subsidence and predicts the maximum subsidence amount.

According to the measured road and ground surface subsidence values, the invention judges whether the road and ground surface subsidence exceeds the safety control standard and the reliability of the adopted engineering measures. And comparing the stage deformation rate and the deformation with the control standard, judging the early warning state of the monitoring point, if the data display reaches the warning standard, analyzing and confirming that abnormal conditions exist, encrypting the monitoring frequency, and performing related processing in time.

The invention can judge the reason causing the ground surface settlement by processing and analyzing the data and combining the specific construction condition, and adopt related measures to reduce the ground surface settlement. Moreover, the invention can realize whole-process monitoring and further enhance the effect of information-based construction.

Specifically, the processing and analysis of the monitoring data of the present invention are as follows.

The surface subsidence caused by the shield process of the initial tunnel is monitored, relevant data of the surface subsidence is collected and analyzed, and a distribution fitting curve of subsidence-time is shown in fig. 5.

The shield of the first tunnel is preparing before construction, and the second tunnel is constructed to ring 348 at the same time, at this moment, the deformation of the earth surface of the stacking section caused by the construction of the second line shield is basically finished, and the first to sixth monitoring sections are continuously monitored until the settlement is basically stable.

As shown in fig. 5, the maximum sedimentation at the second monitored section is 5.93mm, which is slightly less than the sedimentation value relative to the other monitored sections. The reason is that the second monitoring section is in the shield starting stage, the shield propelling speed is slow, the reinforcing effect of the starting end is good, and the like.

As can be seen from FIG. 5, the settlement curves at the first and second monitoring sections are asymmetrically distributed along the center of the tunnel, the maximum settlement of each monitoring section occurs on the middle line of the tunnel and gradually decreases along the transverse direction of the tunnel, and the ground surface of the region far from the middle line has smaller bulges which are less than 2mm on average.

According to the monitoring result, the sedimentation values of the first and second monitoring sections which are covered with the silty clay are integrally smaller than those of the third, fourth, fifth and sixth monitoring sections which are covered with the sandy gravel stratum. The average sedimentation value at the first and second monitoring sections is about 7 mm. The mean sedimentation values of the other four monitored sections were around 12 mm. Under the same construction condition, the settlement of the earth surface with the upper covering soil being the silty clay is slightly less than that of the earth surface with the upper covering soil being the sand gravel layer.

According to the monitoring results shown in fig. 5, when the third, fifth and sixth monitoring sections pass through the soil layer and the overlying soil has substantially the same properties, the average settlement is sequentially increased, which is caused by the fact that the tunnel burial depth is continuously reduced along the tunneling direction.

As seen from figure 5, the settlement monitoring points 43 and 44 of the fourth monitoring section have large fluctuation, which may be caused by construction or damage of the monitoring points.

The overall monitoring result shows that the maximum sedimentation amount of the stacking section appears on the fourth monitoring section, and the maximum sedimentation is 19.08 mm. Within the design allowable range, the settlement of other monitoring sections is less than 15.00 mm. In the field inspection process, the shield has proper construction parameters, good posture, no need of large deviation correction and the like, and good overall construction condition of the off-line tunnel at the stacking section.

Monitoring the secondary vibration influence caused in the shield process of the initial tunnel, collecting relevant data of the surface subsidence, and fitting curves of the subsidence-time distribution are shown in fig. 6 and 7.

The construction of the first tunnel 1 generates secondary disturbance to the stratum to cause secondary settlement of the earth surface, and then six monitoring sections from the first monitoring section to the sixth monitoring section are monitored until the settlement of the earth surface is basically stable.

As can be seen from fig. 6 and 7, the first tunnel construction causes the ground surface to have a tendency of rising first and then sinking, because the second tunnel has a good reinforcing effect, and the shield extrudes the front soil body before reaching the monitoring point to cause the ground surface to have a tendency of rising upwards. When the shield body passes through the monitoring point, the peripheral soil body loses the support of the shield shell and is supported by unset or incompletely set slurry instead, and the ground surface has a tendency of sedimentation. And after the shield passes through the shield, secondary slurry supplement is carried out in time, and the ground surface settlement gradually becomes stable. As can be seen from fig. 2 and 3, the maximum sedimentation value of the first monitoring cross section is 8.45mm, and the maximum sedimentation value of the second monitoring cross section is 12.35mm, so that the control effect on the ground surface sedimentation is good.

As indicated in fig. 8 and 9, the settling law of the third monitoring section is different from the settling law of the second monitoring section. The third monitoring section has no tendency to bulge during the first tunnel construction, and the settlement is started when the shield reaches the monitoring point. In the propelling process of the shield, the settlement of the third monitoring section is continuously increased, the settlement rate is high, and the surface settlement obviously tends to exceed the specified value by 30 mm. And in 10 months and 15 days, the grouting slurry is synchronously replaced by cement-water glass slurry, and the double-liquid slurry is timely used for secondary slurry supplement in an area with an overlarge sedimentation rate, so that the problem of the overlarge sedimentation rate is basically controlled, but the maximum sedimentation amount of the third monitoring section still reaches 34.26 mm.

The settlement of the earth surface of the third monitoring section is more than that of the second monitoring section. After the summary analysis, the reason for the excessive settlement of the third monitoring section is as follows: and the interlayer soil of the third monitoring section between the first tunnel and the second tunnel is not reinforced, so that the settlement is overlarge. The second monitoring section is not subjected to interlaminar soil reinforcement and does not have large settlement, because the second monitoring section mainly passes through the soil layer and is mainly a silty clay layer, and the interlaminar soil reinforcement is not needed when the second monitoring section passes through the silty clay layer. However, the soil layer penetrated by the third monitoring section is mainly a sand-gravel layer, the sand-gravel layer needs to be subjected to interlaminar soil reinforcement, and the soil body of the sand-gravel layer to be penetrated should be subjected to interlaminar soil reinforcement.

As can be seen from fig. 9, the maximum settlement of the fourth monitoring section is 23.22mm, the control effect of the surface settlement is relatively good, and the trend of settlement after rising is similar to the settlement law of the second monitoring section. The control effect of the surface subsidence of the fourth monitoring section is better than that of the third monitoring section, and the reason is that the soil body between the upper and lower tunnel layers is reinforced. Therefore, when the shield tunnel penetrates through the soil layer, the soil between the layers does not need to be reinforced, and when the shield tunnel penetrates through the soil layer, the soil between the layers needs to be reinforced.

As can be seen from fig. 10, the ground surface tends to rise first during the shield advance, but the ground surface subsidence rate is too high from 26 days at 10 months to 28 days at 10 months, and the maximum subsidence rate reaches 4 mm/day. From day 29 of 10 months, the rate of surface subsidence decreased and the surface subsidence tended to stabilize. On-site reconnaissance shows that during the period from 26 days in 10 months to 28 days in 10 months, the shield breaks down and stops propelling, and the shield recovers normal propelling in 29 days in 10 months. Before the shield stops propelling, although the soil output is reduced, the shield continues propelling to enable the soil pressure in the soil cabin to be slightly larger than the set soil pressure, the shutdown time is long, other measures for preventing the shield from retreating are not taken, and the ground surface sedimentation rate is too high during the shutdown.

As can be seen from fig. 11, the maximum settlement amount of the ground surface of the sixth monitoring section is 17.81mm, the ground surface settlement control effect is relatively good, and the trend of settlement after rising is similar to the second and fourth monitoring sections.

The settlement maps of the second, fourth and sixth monitoring sections can show that: the influence of the shield propulsion after the stacking section on the ground surface tends to rise and then subside, and under the condition of good effect of various settlement control measures, the later subsidence value is not large and is within the allowable range of the ground surface subsidence.

According to the settlement maps of the ground surfaces of the second, fourth and sixth monitoring sections, the ground surface settlement caused by the propulsion of the lower hole tunnel accounts for 76.65% of the maximum total settlement, and the ground surface settlement caused by the propulsion of the upper hole tunnel accounts for 23.35% of the total settlement. According to the settlement maps of the ground surfaces of the third monitoring section and the fifth monitoring section, the ground surface settlement caused by the propulsion of the lower hole tunnel accounts for 34.78% of the maximum total settlement, and the ground surface settlement caused by the propulsion of the upper hole tunnel accounts for 65.22% of the total settlement.

It can be seen that the main reason for causing the ground subsidence is the propulsion of the tunnel in the lower hole under the condition that the ground subsidence control of the tunnel in the upper hole is good, and the main reason for causing the ground subsidence is the propulsion of the tunnel in the upper hole under the condition that the ground subsidence control of the tunnel in the upper hole is not ideal. Therefore, in the backward shield propulsion of the stacked tunnel, the ground surface settlement control measures should be strengthened, and secondary ground surface disturbance caused by the backward shield propulsion is reduced as much as possible.

It should be noted that the above-mentioned embodiments are exemplary, and that those skilled in the art, having benefit of the present disclosure, may devise various arrangements that are within the scope of the present disclosure and that fall within the scope of the invention. It should be understood by those skilled in the art that the present specification and figures are illustrative only and are not limiting upon the claims. The scope of the invention is defined by the claims and their equivalents. The present description contains several inventive concepts, such as "preferably", "according to a preferred embodiment" or "optionally", each indicating that the respective paragraph discloses a separate concept, the applicant reserves the right to submit divisional applications according to each inventive concept.

Claims

1. A method for monitoring a complete stacking section of an up-and-down stacking type tunnel is characterized by at least comprising the following steps:

selecting at least one vertical surface vertical to the axis of the stacked tunnel as a monitoring section of the stacked tunnel based on the stacking degree between the stacked tunnels,

determining the number of monitoring points arranged on the monitoring section based on the net distance and/or angle between the stacked tunnels corresponding to the monitoring section,

and carrying out settlement data processing and analysis based on the settlement data sent by the monitoring points.

2. The full stacking segment monitoring method of an up-down stacking type tunnel according to claim 1, wherein the stacking degree is related to a horizontal distance, a vertical distance and a radius of a tunnel axis between at least two tunnels,

，

the radius of the first tunnel is indicated,

representing the radius of the second tunnel.

3. The method of monitoring full landing stages of an up-down landing tunnel according to claim 2, wherein the net spacing and/or angle between the landing tunnels is related to a maximum settlement value,

the number of monitoring points and the distribution range are set based on the relative association of the net spacing and/or angle between tunnels and the maximum settlement value.

4. The full stacking segment monitoring method of an up-down stacking type tunnel according to any one of claims 1 to 3, further comprising:

adjusting the frequency of settlement data collection based on changes in the first and/or second distances of the excavation face from the monitored face.

5. The method of monitoring a complete stacking section of an up-down stacking type tunnel according to claim 4,

when the first and/or second distance between the tunneling surface and the monitoring section is not larger than a first threshold value, the collection frequency of the settlement data is a first frequency;

when the first and/or second distance between the tunneling surface and the monitoring section is larger than a first threshold and not larger than a second threshold, the collection frequency of the settlement data is a second frequency;

and when the first and/or second distance between the heading face and the monitoring section is larger than a second threshold value, the collection frequency of the settlement data is a third frequency.

6. The method of monitoring a complete stacking section of an up-down stacking type tunnel according to claim 4, further comprising:

and in the case of stable ground surface settlement, adjusting the collection frequency of settlement data to be a fourth frequency.

7. The method of monitoring a complete stacking section of an up-down stacking type tunnel according to claim 6, further comprising:

8. The method of monitoring a complete stacking section of an up-down stacking type tunnel according to claim 7, further comprising:

and predicting the maximum sedimentation amount based on a sedimentation-time distribution fitting curve of the surface sedimentation.

9. The method for monitoring the complete stacking section of the up-down stacking type tunnel according to claim 8, wherein the condition that the ground surface settlement is stable at least comprises the following steps:

the amount of convergence is 80% or more of the total amount of convergence.

10. A monitoring device for the complete overlapping section of an up-down overlapping type tunnel at least comprises a plurality of monitoring units, and is characterized in that the monitoring units form monitoring points for monitoring the surface subsidence after being buried underground,

the monitoring section where the monitoring point is located is at least one vertical surface which is selected based on the stacking degree among the stacking type tunnels and is vertical to the axis of the stacking type tunnels,

the number of monitoring points of the monitoring section is determined based on the net distance and/or angle between the stacked tunnels corresponding to the monitoring section.