Cross-sea immersed tube tunnel siltation and sudden siltation load calculation method

Abstract

The application discloses a kind of cross-sea immersed tunnel siltation and sudden silt load calculation method, comprising: sufficient investigation, collect tunnel area marine environment monitoring data basis, theoretical analysis, according to field test results, establish siltation thickness theoretical model and calculation method under two conditions of sand mining open period and closed period.According to the characteristics of the project area, the siltation load calculation model is established, and the siltation thickness is layered and stacked based on the siltation thickness model.The total load and the incremental load of the tunnel siltation under the siltation state are established.According to the collapse and formation characteristics of the sudden silt material in seawater, a marine sudden silt geometric model is established.The probability density function is used to establish the sudden silt spatial distribution function and the corresponding sudden silt load distribution function.According to the application, the theoretical model and calculation method of the marine environment siltation load and the disaster load formed by the rare sudden siltation in the project area are established, which provides a practical method for calculating the dynamic load on the immersed tunnel during operation.

Description

Technical Field

[0001] This invention relates to the technical field of immersed tunnel engineering, and in particular to a method for calculating siltation and sudden siltation loads in cross-sea immersed tunnels. Background Technology

[0002] Due to a combination of factors, including tidal forces, regional environmental factors (sand mining, shipping, etc.), changes in seabed topography and geomorphology, tidal current velocity and direction, wave factors (shallow sea), seasonal climate change, and abrupt changes such as shipwrecks, underwater immersed tunnels are inevitably subject to the periodic reciprocating action of siltation loads and the potential threat of sudden siltation loads. Furthermore, due to the complexity of the formation process and spatiotemporal distribution of siltation loads, the uncertainty of sudden siltation events, and the spatial variability of sudden siltation load distribution, there is currently no universally accepted mechanical model or calculation method for siltation loads that can accurately and effectively describe the characteristics of siltation and sudden siltation in the marine environment.

[0003] In light of the above reasons, it is urgent to conduct research on the potential siltation loads and sudden siltation loads on immersed tunnels caused by the siltation environment and siltation state in the tunnel site area. This research aims to establish theoretical models and calculation methods for siltation loads in the marine environment of the engineering area and catastrophic loads caused by rare and sudden siltation. This will provide practical methods for calculating the dynamic load changes on the superstructure of immersed tunnels during their operational period. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method for calculating siltation and sudden siltation loads in cross-sea immersed tunnels. This method establishes a theoretical model and calculation method for siltation loads in the marine environment of the engineering area and catastrophic loads caused by rare and sudden siltation, providing a practical method for calculating the dynamic load changes above the tunnel during its operation. To achieve the above-mentioned objectives and other advantages of this invention, a method for calculating siltation and sudden siltation loads in cross-sea immersed tunnels is provided, comprising the following steps:

[0005] S1. Establish a local polar coordinate system for the tunnel site area of ​​the immersed tunnel;

[0006] S2. Calculate the siltation thickness based on surveys and mathematical statistics;

[0007] S3. Calculate the siltation load;

[0008] S4. Calculate the distribution pattern of sudden siltation and its catastrophic load.

[0009] Preferably, the local polar coordinate system in step S1 includes taking the tunnel K0 position as the origin, the tunnel axis forward as the positive direction, and counterclockwise as the positive angle, and the coordinates of any point are (a, S).

[0010] Preferably, in step S2, the sedimentation thickness Z(a,S,x) at any point (a,S) in the tunnel site area is calculated using partitioned bilinear regression, with the following formula:

[0011]

[0012] ξ was determined by in-situ measurements at no less than 9 points. i With η i The time equilibrium coefficient for sedimentation is λj, which is obtained as follows:

[0013]

[0014] Preferably, in step S3, a layered siltation superposition method is used on the basis of the siltation thickness to establish the total siltation load and the incremental siltation load of the siltation tunnel, and a siltation load calculation model is established according to the siltation characteristics of the engineering area.

[0015] Preferably, the sediment load and its increment are calculated according to the sediment load calculation model as shown in equations (1) and (2):

[0016] P i (α,S,x)=γ w h w +γ x h x +γ g Z i,sum (α,S,x)

[0017] ΔP i (α,S,x)=P i (α,S,x)-γ w {h w +h x +Z i,sum (α,S,x)}

[0018] Where x is the equivalent tidal range;

[0019] γ w -Specific density of seawater, kg / m³ 3 ;

[0020] γ x -Bulk density of the medium in the sediment suspension zone, kg / m³ 3

[0021] γ g -Specific density of the medium in the siltation consolidation zone, kg / m³ 3 .

[0022] Preferably, in step S4, based on the collapse and formation characteristics of the silt deposits in seawater, a probability density function is used to establish the spatial distribution function of the silt deposits and the corresponding silt load distribution function, wherein the formula for the geometric morphology function of the silt deposits is:

[0023] The specific calculation function for Z(x,y) can be determined based on the collapse angle α, height H, and width L.

[0024] The formula for the distribution function of sudden siltation load is:

[0025] This function can effectively simulate arbitrary siltation thickness and siltation load by varying the collapse angle, accumulation height, and siltation width.

[0026] Compared with the prior art, the beneficial effects of this invention are: to establish a theoretical model and calculation method for the marine environmental siltation load and the catastrophic load formed by rare sudden siltation in the engineering area, to provide a practical method for calculating the dynamic change load of the upper part of the immersed tunnel during the operation period, so that the method can be used to calculate the dynamic change load of any type of marine environmental siltation on the immersed tunnel and to calculate the load formed by marine siltation on the tunnel. Attached Figure Description

[0027] Figure 1 A diagram showing the relationship between equivalent tidal range and sediment content in the engineering area based on the calculation method for siltation and sudden siltation loads of the cross-sea immersed tunnel according to the present invention.

[0028] Figure 2 A diagram showing the relationship between siltation thickness and sediment content in the tunnel site area according to the calculation method for siltation and sudden siltation load of the cross-sea immersed tunnel of the present invention.

[0029] Figure 3 This diagram illustrates the relationship between the siltation thickness and the equivalent tidal range in the tunnel site area, based on the calculation method for siltation and sudden siltation loads of the cross-sea immersed tunnel according to the present invention.

[0030] Figure 4 This is a local coordinate system diagram of the tunnel site area based on the calculation method for siltation and sudden siltation loads of the cross-sea immersed tunnel according to the present invention;

[0031] Figure 5 A diagram of a siltation load calculation model based on the siltation distribution characteristics, according to the siltation and sudden siltation load calculation method for cross-sea immersed tunnels of the present invention.

[0032] Figure 6 This is a geometric model of marine siltation morphology based on the calculation method for siltation and sudden siltation load of the cross-sea immersed tunnel according to the present invention. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Reference Figure 1-6 A method for calculating siltation and sudden siltation loads in a cross-sea immersed tunnel includes the following steps: S1, establishing a local polar coordinate system for the tunnel site area;

[0035] S2. Calculate the siltation thickness based on surveys and mathematical statistics;

[0036] S3. Calculate the siltation load;

[0037] S4. Calculate the distribution pattern of sudden siltation and its catastrophic load.

[0038] Furthermore, the local polar coordinate system in step S1 includes taking the tunnel K0 position as the origin, the tunnel axis forward as the positive direction, and counterclockwise as the positive angle, with the coordinates of any point being (a, S). Through the analysis of comprehensive factors such as tidal factors, regional environmental factors (sand mining, shipping, etc.), seabed topography, geomorphological change factors, tidal current velocity, flow direction, wave factors (shallow sea), and seasonal climate change, and taking the tunnel K0 position as the origin, the tunnel axis as the positive direction, and the counterclockwise as the positive angle, a formula for calculating the siltation thickness at any location in the tunnel area is established.

[0039] Furthermore, considering the actual conditions of the Shenzhen-Zhongshan immersed tunnel project, the risk posed by siltation to the tunnel is the vertical displacement of the entire tunnel segment and the rotation or shear displacement of the tunnel segment joints caused by uneven additional loads. The greatest risk is the vertical deflection and shear displacement of the tunnel segment joints. To minimize the workload while better reflecting tunnel risk control, it is recommended to use a partitioned bilinear regression method. In step S2, the siltation thickness Z(a,S,x) at any point (a,S) in the tunnel site area is calculated using partitioned bilinear regression, with the formula:

[0040]

[0041] ξ was determined by in-situ measurements at no less than 9 points. i With η i The time equilibrium coefficient for sedimentation is λj, which is obtained as follows:

[0042]

[0043] Furthermore, in step S3, a layered siltation superposition method is adopted based on the siltation thickness to establish the total siltation load and the incremental siltation load of the siltation tunnel, and a siltation load calculation model is established according to the siltation characteristics of the engineering area.

[0044] Furthermore, the sediment load and its increment are calculated according to the sediment load calculation model, as shown in equations (1) and (2):

[0045] P i (α,S,x)=γ w h w +γ x h x +γ g Z i,sum (α,S,x)

[0046] ΔP i (α,S,x)=P i (α,S,x)-γ w {h w +h x +Z i,sum (α,S,x)}

[0047] Where x is the equivalent tidal range;

[0048] γ w -Specific density of seawater, kg / m³ 3 ;

[0049] γ x -Bulk density of the medium in the sediment suspension zone, kg / m³ 3

[0050] γ g -Specific density of the medium in the siltation consolidation zone, kg / m³ 3，

[0051] Specifically, bilinear calculation formulas for siltation thickness and load distribution are established according to the length of a single tunnel segment. When calculating the stress of the tunnel segment and performing strength analysis, the full load calculation formula is used. When calculating the vertical displacement of the tunnel segment and verifying the watertightness of the waterstop, the incremental load calculation formula is used.

[0052] Furthermore, the basic assumptions are:

[0053] [1] A sudden siltation object has the property of shear collapse under its own weight.

[0054] [2] The collapsed bodies have the same distribution along any orthogonal vertical plane.

[0055] [3] After the siltation material stabilizes, it becomes a three-dimensional distribution of a rotating surface.

[0056] Based on the above assumptions, the geometry of the siltation and its load model are established as follows: Figure 6 As shown.

[0057] In step S4, based on the collapse and formation characteristics of the silt deposits in seawater, a probability density function is used to establish the spatial distribution function of the silt deposits and the corresponding silt load distribution function. The formula for the geometric morphology function of the silt deposits is as follows:

[0058] The specific calculation function for Z(x,y) can be determined based on the collapse angle α, height H, and width L.

[0059] The formula for the distribution function of sudden siltation load is:

[0060] This function can effectively simulate arbitrary siltation thickness and siltation load by varying the collapse angle, accumulation height, and siltation width.

[0061] This algorithm can be used to i) calculate the dynamic load on immersed tunnels caused by siltation of any type of marine environment; ii) calculate the load on tunnels caused by sudden marine siltation.

[0062] Moreover, as Figure 1-3 As shown, based on thorough research and collection of marine environmental monitoring data in the tunnel area of ​​the Shenzhen-Zhongshan Bridge project, theoretical analysis and, based on field test results, establish formulas for calculating siltation thickness under two conditions: open and closed sand mining periods.

[0063] In the formula: Z - sediment thickness (m / d), x - equivalent tidal range (m)

[0064] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention, and applications, modifications and variations of the invention will be obvious to those skilled in the art.

[0065] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for calculating siltation and sudden siltation loads in a cross-sea immersed tunnel, characterized in that, Includes the following steps: S1. Establish a local polar coordinate system for the tunnel site area of ​​the immersed tunnel; S2. Based on surveys and mathematical statistics, the siltation thickness is calculated, using a local polar coordinate system including tunnel sections. K Position 0 is the origin of the coordinate system, the forward direction along the tunnel axis is the positive direction, and counterclockwise is the positive angle. The coordinates of any point are ( a , S ); By employing partitioned bilinear regression, the calculation of any point in the tunnel site area ( a , S The thickness of the sediment is Z ( a, S, x The formula is: Z i ( a, S, x )= ； Determined by in-situ measurements at no less than 9 points. and The time equilibrium coefficient of sedimentation is j obtains: ； S3. Calculate the siltation load. By using a layered siltation superposition method based on the siltation thickness, establish the total siltation load and the incremental siltation load of the siltation tunnel. Based on the siltation characteristics of the engineering area, establish a siltation load calculation model. The siltation load and its increment corresponding to the siltation load calculation model are calculated as shown in equations (1) and (2): ； in, - Equivalent tidal difference; -Specific density of seawater, kg / m³ 3 ; -Bulk density of the medium in the sediment suspension zone, kg / m³ 3 -Specific density of the medium in the siltation consolidation zone, kg / m³ 3 ; S4. Calculate the distribution morphology of sudden siltation and its catastrophic load. Based on the collapse and formation characteristics of sudden siltation material in seawater, a probability density function is used to establish the spatial distribution function of sudden siltation and the corresponding sudden siltation load distribution function. The formula for the geometric morphology function of sudden siltation is as follows: (3) Based on the collapse angle a ,high H ,width L The specific Z ( x, y )Specific calculation function; The formula for the distribution function of sudden siltation load is: (4) This function can effectively simulate arbitrary siltation thickness and siltation load by changing the collapse angle, siltation height and siltation width.

2. The method for calculating siltation and sudden siltation loads in a cross-sea immersed tunnel as described in claim 1, characterized in that, The local polar coordinate system in step S1 includes taking the tunnel. K Position 0 is the origin of the coordinate system, the forward direction along the tunnel axis is the positive direction, and counterclockwise is the positive angle. The coordinates of any point are ( a ,, S ).

Images