CN117027952A - Monitoring and early warning method for river bed scouring risk in subway river-crossing tunnel region - Google Patents

Abstract

The invention provides a monitoring and early warning method for the scouring risk of a river bed in a tunnel region crossing a river of a subway, belongs to the technical field of water conservancy and hydropower engineering, is based on the monitoring of a conventional tunnel protection region crossing the river and a tunnel line position upstream and downstream scouring region which possibly affects the safety of the tunnel crossing the river, provides a control section for monitoring the deformation of the river bed in the tunnel region crossing the river for the first time and a determination method thereof, and provides a method for classifying and early warning the scouring risk of the river bed in the tunnel region crossing the river according to the monitoring result of the river bed of the control section, and can provide technical basis for guaranteeing the safety of the tunnel crossing the river and the operation management of the tunnel crossing the river.

Description

Monitoring and early warning method for river bed scouring risk in subway river-crossing tunnel region

Technical Field

The invention relates to a monitoring and early warning method for river bed scouring risk in a tunnel region crossing a river of a subway, and belongs to the technical field of water conservancy and hydropower engineering.

Background

The main body structure of the river crossing tunnel of the estuary urban rail transit project is buried under a river bed, complex runoff flood, tidal reciprocating flow, local hydraulic phenomenon of adjacent river-related buildings, human activity influence and the like tend to cause the river bed to produce a flushing and silting change, further the thickness of an upper covering layer of the river crossing tunnel of the rail transit project is changed, and once the river bed is continuously cut down, the thickness of the upper covering layer of the tunnel is smaller than the minimum safe covering thickness, the floating stability of the river crossing tunnel structure is likely to be unsatisfied, and further the operation safety of the rail transit project is influenced. Therefore, the risk of the danger of the river crossing tunnel of the track traffic engineering is required to be emphasized and prevented, and the risk of the river bed scouring in the river crossing tunnel area is very necessary to be monitored and early warned.

At present, for the monitoring of the riverbed of a river crossing tunnel area of a large river, the main emphasis is on analyzing the river bed erosion and siltation form change of the river crossing tunnel area and the soil covering thickness change at the top of the river crossing tunnel, and no monitoring and early warning method aiming at the river bed erosion and deformation risk of the river crossing tunnel area exists, so that a tunnel operation management unit cannot effectively make early warning response according to the river bed monitoring result of the river crossing tunnel area.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a monitoring and early warning method for the scouring risk of the river bed in a tunnel region crossing a river of a subway, which comprises the following steps:

(1) Analyzing the evolution of the river bed of the river-crossing tunnel section, and determining the evolution trend of the river bed of the river-crossing tunnel section and main scouring risk sources;

(2) A river bed deformation monitoring scheme of the river-crossing tunnel area is formulated;

(3) Determining the position of a cross section of a river bed deformation monitoring control section in a river-crossing tunnel protection area;

(4) And providing a river bed scouring deformation risk classification and early warning scheme in the river-crossing tunnel region.

Preferably, the step (1) specifically includes: collecting historical actual measurement topographic data of a river section of a river-crossing tunnel, sleeving and drawing river terrains of different years, analyzing the characteristics of river bed plane and section erosion and siltation change of the river section of the river-crossing tunnel, studying and judging the evolution trend of the river bed of the river-crossing tunnel, and analyzing the main cause of the river bed erosion aiming at the flushed river-crossing tunnel, thereby determining the main risk source for the river bed erosion.

Preferably, the main scouring risk sources of the river bed in the step (1) specifically include: flood scouring, tidal reciprocation, river dredging and excavation, and local hydraulic scouring influence of river-related buildings of engineering river reach.

Preferably, the step (2) specifically includes: based on the evolution trend of the river bed of the river-crossing tunnel engineering area and the main scouring risk source determined in the step (1), a river bed deformation monitoring scheme of the river-crossing tunnel area is formulated; the monitoring range comprises a tunnel line position upstream and downstream flushing area and a tunnel protection range which can influence the safety of the tunnel passing through the river; monitoring for 2 times a year, wherein the time is the first time before the flood season, and the time is the last time after the flood season; performing terrain monitoring by adopting RTK and multi-beam sounding system equipment; the river bed monitoring adopts the precision not lower than 1:500.

Preferably, the key monitoring content in the step (2) includes deformation of the cross section of the tunnel line and elevation change of the deepest point of the cross section, deformation of the river bed of the cross section and elevation change of the deepest point of the cross section controlled by the protection area of the cross section of the tunnel, development situation of the flushing area on the upstream and downstream of the tunnel line and elevation change of the deepest point of the tunnel line, which may affect the safety of the cross section of the tunnel.

Preferably, the step (3) specifically includes: the control section is located in the protection area of the river-crossing tunnel, the control section is not too far away from the river-crossing tunnel, the risk brought by the terrain change to the river-crossing tunnel can not be accurately transmitted too far, so that the monitoring significance is lost, the safety margin is insufficient if the control section is too close, the risk feedback of the river bed scouring is not timely, and the risk degree is increased; the river bed scouring deformation disclosed by the control section and the river bed scouring deformation of the tunnel line section can be required to establish a certain connection, and the influence of the river bed deformation of the river bed scouring region on the upstream and downstream of the river crossing tunnel line position on the thickness of the safety overburden layer at the top of the river crossing tunnel can be determined and early warned through the monitoring result of the river bed scouring deformation of the control section.

Preferably, in the step (3), in order to reasonably determine the position of the control section, introducing a critical slope rate i0 of a natural scouring pit of a river bed and a minimum surplus thickness h of a soil covering layer at the top of the tunnel; i0 is obtained by statistical analysis of a plurality of actual measurement scour pit slope rates of a river where a river-crossing tunnel project is located in different years, and i0 corresponds to a scour pit minimum slope rate obtained by statistical analysis according to a plurality of actual measurement scour pit data; h is the difference value of the highest point elevation Z1 of the river bed at the top of the tunnel minus the flushing depth control elevation Z2 of the river bed of the river-crossing tunnel, and if the thickness of the soil covering layer at the top of the tunnel meets the safety requirement, the requirement h is more than 0; the control section position is jointly determined by i0 and h, and the horizontal projection distance L=h/i 0 between the control section and the outer side of the outer line of the tunnel structure.

Preferably, the step (4) specifically includes: introducing a river bed scouring deformation risk monitoring early warning value (expressed by delta H, unit m) of the river-crossing tunnel region, wherein delta H is the difference value between the deepest point of the control section and the scouring depth control elevation of the river-crossing tunnel in the step 3; dividing the river bed scouring risk of the river-crossing tunnel region into 4 grades, wherein the river bed scouring risk is as follows:

(1) blue early warning, risk level IV, early warning value is more than or equal to 0 and less than 0.5H, and the scouring has little influence on the thickness of the soil covering at the top of the tunnel passing through the river;

(2) yellow early warning, risk level III, early warning value range 0 > [ delta ] H not less than-0.5H, wherein the flushing can have a large influence on the thickness of the earth covering at the top of the river-crossing tunnel, the safety margin of the earth covering of the river-crossing tunnel can be reduced to 0.5H to the maximum, and a certain threat is generated on the safety of the river-crossing tunnel;

(3) orange early warning, risk level II, early warning value range-0.5H >. DELTA.H is more than or equal to-H, and at the moment, flushing can possibly cause the maximum reduction of the soil covering thickness safety margin of the river-crossing tunnel to 0m, so that a great threat is generated to the safety of the river-crossing tunnel;

(4) red early warning, risk level I, early warning value range DeltaH < -H, and the scour at this time can possibly cause insufficient thickness of the safety earthing at the top of the river-crossing tunnel to influence the safety of the river-crossing tunnel.

The invention provides a river bed deformation monitoring control section of a river-crossing tunnel region and a determination method thereof for the first time based on the monitoring of a conventional river-crossing tunnel protection region and a tunnel line position upstream and downstream flushing region which possibly affects the safety of the river-crossing tunnel, and provides a method for classifying and early warning the river bed flushing risk level of the river-crossing tunnel region according to the monitoring result of the river bed of the control section, which can provide technical basis for guaranteeing the safety of the river-crossing tunnel and the operation management of the river-crossing tunnel.

Drawings

FIG. 1 is a form view of a 2022 year riverbed of the Huzhou rail transit No. 1 river-crossing section;

FIG. 2 is a schematic diagram of a river bed scouring risk monitoring scheme of Fuzhou rail transit No. 1 line river-crossing section;

FIG. 3 is a graph showing the statistical result of natural scour pit slope rate of the river bed in the North and south of Minjiang.

Detailed Description

The invention is described in detail below with reference to the accompanying drawings.

Example 1

As shown in fig. 1, 2 and 3, the monitoring and early warning of the river bed change in the operating period of the tunnel in the north port of the downgoing Min river of track traffic engineering No. 1 in Fuzhou city are taken as an example for illustration.

1. And (5) analyzing the evolution of the river bed of the river-crossing section of track traffic No. 1 line in Fuzhou city and main scouring risk sources. The actual measurement data show that the river bed in the river-crossing tunnel area of the No. 1 line is complex in shape, the river bed is divided into branches, the left branch of a river is taken as a main river groove, local flushing pits exist in the left branch of a river and the right branch of a river of the river-crossing tunnel and the liberation bridge, the flushing pit of the left branch of a river is obviously larger than the flushing pit of the right branch of a river, the flushing pit of the left branch of a river is closer to the river-crossing tunnel line (the deepest point is positioned at the upper stream of the river-crossing tunnel by about 100 m), the river-crossing tunnel is threatened greatly, and the river bed in 2022 years is in shape as shown in fig. 1. According to the comparative analysis of the topographic data of the same mapping scale in 2011, 2017 and 2022, the flushing pit has a tendency to further develop due to the fact that the plane is enlarged and the longitudinal direction of the flushing pit is brushed in recent years, as shown in table 1. Analysis of the evolution of the river bed shows that the bridge pier of the liberation bridge and the riprap foundation transversely stretching at the bottom of the bridge are obvious in water accumulation, so that the water level difference between the upper part and the lower part of the bridge is large, the flow speed under the bridge is large, the flow state is very complex, in addition, the left bank forms a folded angle at the liberation bridge and forms a large included angle with the water flow line, the water flow direction is greatly deflected and swirled, and the river bed between the left branch of a river of the Zhongzhou island and the line-through tunnel line of line 1 of the liberation bridge is greatly flushed, and the safety of the line-through tunnel of line 1 is threatened. Namely, the river bed flushing threat of the No. 1 line river-crossing tunnel area mainly comes from the development of a left branch of a river flushing pit.

TABLE 1 Fuzhou rail transit No. 1 line and free bridge interval scour pit variation

2. And (5) making a river bed deformation monitoring and analyzing scheme in the river-crossing tunnel region. And (3) based on the river bed evolution and main scouring risk source analysis results of the river bed crossing tunnel engineering area in the step (1), a river bed deformation monitoring scheme of the river bed crossing tunnel area is formulated. The monitoring range comprises a flushing pit between the amplifying bridge and the river-crossing tunnel and the protection range of the river-crossing tunnel (taking the range of 100m on the upstream and downstream of the outer edge of the tunnel structure). The monitoring is carried out for 2 times a year, the time is before the flood season, and the time is after the flood season. And adopting RTK and multi-beam sounding system equipment to perform terrain monitoring. The mapping precision is not lower than 1:500. The key monitoring content comprises the deformation of the section of the river-crossing tunnel line and the elevation change of the deepest point of the section, the control of the deformation of the river bed of the section of the river-crossing tunnel protection area and the elevation change of the deepest point of the section, the flushing and silting change of the river bed plane of the river-crossing tunnel protection area, the development situation of the scouring pit of the left branch of a river of the Zhongzhou island and the elevation change of the deepest point of the scouring pit, and the monitoring scheme is shown in figure 2.

3. And (5) determining the position of the section of the river bed deformation monitoring control section in the river-crossing tunnel protection area. The control section position is determined by the critical slope rate i0 of a natural scouring pit of a river bed and the minimum surplus thickness h of a soil covering layer at the top of a tunnel, and the horizontal projection distance L=h/i between the control section and the outer side of the outer line of the tunnel structure ₀ 。i ₀ According to a plurality of actual measurement scour pit slope rates in different years of a river (river section) where a river-crossing tunnel engineering is located, obtaining i ₀ And the minimum slope rate of the flushing pit is obtained according to statistical analysis of a large number of measured flushing pit data. According to the statistics result of 580 groups of flushing pit slope rate data of different years of the south-north harbor downstream of Minjian, the natural flushing pit slope rate of the Minjian south-north harbor riverbed is between 0.1 and 0.2 and accounts for about 53.1 percent, about 24.14 percent of 0.2 to 0.25, about 8.97 percent of 0.25 to 0.3, about 6.90 percent of 0.3 to 0.33 and about 6.90 percent of more than 0.33, which is shown in figure 3. Therefore, the flushing pit slope rate is not more than 0.1, namely, the minimum slope rate i0 of the river flushing pit where the line 1 is located is determined to be 0.1.h is the difference value of the highest point elevation Z1 of the river bed at the top of the tunnel minus the flushing depth control elevation Z2 of the river bed of the river-crossing tunnel, and the actual measurement data Z is used ₁ Is-15.57 m, Z ₂ Is-18.57 m, and the preparation method is as follows: h=z ₁ -Z ₂ ＝3m；L＝h/i ₀ =30m, i.e. control section is located on line 130m upstream of the cross section.

4. And determining the grade division and early warning scheme of the river bed scouring deformation risk in the river-crossing tunnel region.

And (3) introducing a river bed scouring deformation risk monitoring and early warning value (expressed as delta H, in unit m) in the river-crossing tunnel region, wherein delta H is the difference value between the deepest point of the control section and the scouring depth control elevation of the river-crossing tunnel in the step (3). Dividing the river bed scouring risk of the river-crossing tunnel region into 4 grades, wherein the river bed scouring risk is as follows: (1) blue early warning, risk level IV, early warning value is more than or equal to 0 and less than 0.5H, and the scouring has little influence on the thickness of the soil covering at the top of the tunnel passing through the river; (2) yellow early warning, risk level III, early warning value range 0 > [ delta ] H not less than-0.5H, wherein the flushing can have a large influence on the thickness of the earth covering at the top of the river-crossing tunnel, the safety margin of the earth covering of the river-crossing tunnel can be reduced to 0.5H to the maximum, and a certain threat is generated on the safety of the river-crossing tunnel; (3) orange early warning, risk level II, early warning value range-0.5H >. DELTA.H is more than or equal to-H, and at the moment, flushing can possibly cause the maximum reduction of the soil covering thickness safety margin of the river-crossing tunnel to 0m, so that a great threat is generated to the safety of the river-crossing tunnel; (4) red early warning, risk level I, early warning value range DeltaH < -H, and the scour at this time can possibly cause insufficient thickness of the safety earthing at the top of the river-crossing tunnel to influence the safety of the river-crossing tunnel.

Step 3 shows that the minimum margin thickness h of the top soil covering layer of the Fuzhou No. 1 line tunnel is 3m, namely, for Fuzhou No. 1 line, the early warning and dividing of the river bed scouring deformation risk is specifically as follows: (1) blue early warning, risk level IV, early warning value is more than or equal to 0 and less than 1.5, and the scouring has little influence on the thickness of the soil covering at the top of the tunnel passing through the river; (2) yellow early warning, risk level III, early warning value range 0 > [ delta ] H not less than-1.5, wherein the scouring can have a great influence on the thickness of the earth covering at the top of the river-crossing tunnel, the safety margin of the earth covering of the river-crossing tunnel can be reduced to 1.5 to the maximum, and a certain threat is generated on the safety of the river-crossing tunnel; (3) orange early warning, risk level II, early warning value range-1.5 >. DELTA.H is more than or equal to-3, and at the moment, the flushing can possibly cause the maximum reduction of the soil covering thickness safety margin of the river-crossing tunnel to 0m, so that a great threat is generated to the safety of the river-crossing tunnel; (4) red early warning, risk level I, early warning value range DeltaH < -3, and the scour at this time can possibly cause insufficient thickness of the safety earthing at the top of the river-crossing tunnel to influence the safety of the river-crossing tunnel.

According to the monitoring result of the river bed in 2022, the elevation of the deepest point of the section is controlled to be-17.5 m, the obtained delta H is 1.07, the early warning value is more than or equal to 0 and less than 1.5, and the river bed scouring risk grade of the current No. 1 line river-crossing tunnel area is judged to be grade IV.

The examples described above only represent preferred embodiments of the present invention, which are described in more detail, but the present invention is not limited to these examples, and it should be noted that it is obvious to those skilled in the art that the present invention is not limited to these examples. Any modifications thereof fall within the scope of the present invention without departing from the spirit of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims (8)

1. The monitoring and early warning method for the river bed scouring risk of the subway river-crossing tunnel area is characterized by comprising the following steps of:

(1) Analyzing the evolution of the river bed of the river-crossing tunnel section, and determining the evolution trend of the river bed of the river-crossing tunnel section and main scouring risk sources;

(2) A river bed deformation monitoring scheme of the river-crossing tunnel area is formulated;

(3) Determining the position of a cross section of a river bed deformation monitoring control section in a river-crossing tunnel protection area;

(4) And providing a river bed scouring deformation risk classification and early warning scheme in the river-crossing tunnel region.

2. The method for monitoring and early warning the scouring risk of the river bed in the tunnel region crossing the river of the subway according to claim 1, wherein the step (1) specifically comprises the following steps: collecting historical actual measurement topographic data of a river section of a river-crossing tunnel, sleeving and drawing river terrains of different years, analyzing the characteristics of river bed plane and section erosion and siltation change of the river section of the river-crossing tunnel, studying and judging the evolution trend of the river bed of the river-crossing tunnel, and analyzing the main cause of the river bed erosion aiming at the flushed river-crossing tunnel, thereby determining the main risk source for the river bed erosion.

3. The method for monitoring and early warning the risk of river bed flushing in a tunnel region crossing a river of a subway according to claim 2, wherein the main source of the risk of river bed flushing in the step (1) specifically comprises: flood scouring, tidal reciprocation, river dredging and excavation, and local hydraulic scouring influence of river-related buildings of engineering river reach.

4. The method for monitoring and early warning the scouring risk of the river bed in the tunnel region crossing the river of the subway according to claim 3, wherein the step (2) specifically comprises the following steps: based on the evolution trend of the river bed of the river-crossing tunnel engineering area and the main scouring risk source determined in the step (1), a river bed deformation monitoring scheme of the river-crossing tunnel area is formulated; the monitoring range comprises a tunnel line position upstream and downstream flushing area and a tunnel protection range which can influence the safety of the tunnel passing through the river; monitoring for 2 times a year, wherein the time is the first time before the flood season, and the time is the last time after the flood season; performing terrain monitoring by adopting RTK and multi-beam sounding system equipment; the river bed monitoring adopts the precision not lower than 1:500.

5. The method for monitoring and early warning the scouring risk of the river bed in the tunnel region of the subway passing through the river according to claim 4, wherein the key monitoring content in the step (2) comprises the deformation of the section of the tunnel line position of the river passing through the river and the elevation change of the deepest point of the section, the control of the deformation of the river bed of the section of the protection region of the tunnel passing through the river and the elevation change of the deepest point of the section, the development situation of the scouring region on the upstream and downstream of the tunnel line position of the river possibly affecting the safety of the tunnel passing through the river and the elevation change of the deepest point thereof.

6. The method for monitoring and early warning the scouring risk of the river bed in the tunnel region crossing the river of the subway according to claim 5, wherein the step (3) specifically comprises: the control section is located in the protection area of the river-crossing tunnel, the control section is not too far away from the river-crossing tunnel, the risk brought by the terrain change to the river-crossing tunnel can not be accurately transmitted too far, so that the monitoring significance is lost, the safety margin is insufficient if the control section is too close, the risk feedback of the river bed scouring is not timely, and the risk degree is increased; the river bed scouring deformation disclosed by the control section and the river bed scouring deformation of the tunnel line section can be required to establish a certain connection, and the influence of the river bed deformation of the river bed scouring region on the upstream and downstream of the river crossing tunnel line position on the thickness of the safety overburden layer at the top of the river crossing tunnel can be determined and early warned through the monitoring result of the river bed scouring deformation of the control section.

7. The method for monitoring and early warning the river bed scouring risk in a tunnel region crossing a river of a subway according to claim 6, wherein in the step (3), in order to reasonably determine the position of the control section, the critical slope rate i0 of a natural scouring pit of the river bed and the minimum surplus thickness h of a covering soil layer at the top of the tunnel are introduced; i0 is obtained by statistical analysis of a plurality of actual measurement scour pit slope rates of a river where a river-crossing tunnel project is located in different years, and i0 corresponds to a scour pit minimum slope rate obtained by statistical analysis according to a plurality of actual measurement scour pit data; h is the difference value of the highest point elevation Z1 of the river bed at the top of the tunnel minus the flushing depth control elevation Z2 of the river bed of the river-crossing tunnel, and if the thickness of the soil covering layer at the top of the tunnel meets the safety requirement, the requirement h is more than 0; the control section position is jointly determined by i0 and h, and the horizontal projection distance L=h/i 0 between the control section and the outer side of the outer line of the tunnel structure.

8. The method for monitoring and early warning the scouring risk of the river bed in the tunnel region crossing the river of the subway according to claim 7, wherein the step (4) specifically comprises: introducing a river bed scouring deformation risk monitoring early warning value (expressed by delta H, unit m) of the river-crossing tunnel region, wherein delta H is the difference value between the deepest point of the control section and the scouring depth control elevation of the river-crossing tunnel in the step 3; dividing the river bed scouring risk of the river-crossing tunnel region into 4 grades, wherein the river bed scouring risk is as follows:

(1) blue early warning, risk level IV, early warning value is more than or equal to 0 and less than 0.5H, and the scouring has little influence on the thickness of the soil covering at the top of the tunnel passing through the river;

(2) yellow early warning, risk level III, early warning value range 0 > [ delta ] H not less than-0.5H, wherein the flushing can have a large influence on the thickness of the earth covering at the top of the river-crossing tunnel, the safety margin of the earth covering of the river-crossing tunnel can be reduced to 0.5H to the maximum, and a certain threat is generated on the safety of the river-crossing tunnel;

(3) orange early warning, risk level II, early warning value range-0.5H >. DELTA.H is more than or equal to-H, and at the moment, flushing can possibly cause the maximum reduction of the soil covering thickness safety margin of the river-crossing tunnel to 0m, so that a great threat is generated to the safety of the river-crossing tunnel;

(4) red early warning, risk level I, early warning value range DeltaH < -H, and the scour at this time can possibly cause insufficient thickness of the safety earthing at the top of the river-crossing tunnel to influence the safety of the river-crossing tunnel.