Method and system for calculating settlement of immersed tube tunnel under deposition load and medium

Abstract

The invention relates to the technical field of immersed tunnels, in particular to an immersed tunnel settlement calculation method, system and medium under a sedimentation load.The method comprises the steps that basic assumption is made based on stress deformation characteristics of an immersed tunnel, and the circulation form of the sedimentation load is determined based on the basic assumption; obtaining a calculation expression of the siltation load changing along with time; calculating the non-linear consolidation settlement of the soil layer of the underlying foundation caused by the sedimentation load; through the compression modulus, the drainage distance, the consolidation coefficient and the cycle period of the foundation soil layer, a Taylor expansion is combined to obtain a calculation expression of foundation settlement changing along with time; based on the bending moment and the shearing force of the Timoshenko beam model, the deflection of the immersed tube tunnel with the different dredging frequencies is determined; determining a settlement value at the left end joint of any pipe joint and a settlement value at the right end joint of any pipe joint according to the transmission deflection difference and the rotation angle between the adjacent pipe joints in the immersed tunnel; according to the method, the calculation accuracy of immersed tunnel sedimentation caused by the sedimentation effect can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of immersed tube tunnels, and in particular to a method, system and medium for calculating the settlement of an immersed tube tunnel under siltation load. Background Art

[0002] In modern cross-sea projects, immersed tube tunnels have become a widely used solution due to their short construction period, excellent waterproof performance and strong geological adaptability. Compared with traditional immersed tube tunnels, shallow buried immersed tube tunnels are relatively simple to construct and maintain, but in the actual operation and maintenance process, they are often faced with the effect of siltation load. Especially during the operation and maintenance period, the effect of siltation load on tunnel deformation has not been fully studied. In recent years, with the acceleration of coastal and waterway construction in my country, many immersed tube tunnels cross busy waterways, most of which are deep-buried immersed tube tunnels. Especially in this case, the pipe sections will be subject to more complex siltation loads during operation. Studies have found that the siltation rate can reach up to 5cm·d-1, and the settlement of the pipe sections caused by siltation loads accounts for about 13% of the total settlement. Especially at the pipe section joints, the influence of settlement differences on the structure is particularly significant. The settlement differences at the pipe section joints will cause uneven settlement in local areas, which can easily lead to excessive settlement or fatigue damage at the joints of the immersed tube tunnel, further affecting the safety of the tunnel structure. Therefore, studying the long-term settlement of immersed tube tunnels under siltation load during operation and maintenance period has important theoretical and practical significance.

[0003] Most existing studies focus on the bending and shear deformation of tunnels, however, the displacement difference of the joints at the pipe joints is often ignored. The displacement difference at the pipe joints has a crucial impact on the overall stability and safety of the tunnel. If this is ignored, it may lead to inaccurate assessment of tunnel deformation, thereby underestimating or ignoring potential risks. Therefore, it is necessary to improve the accuracy of settlement calculation of immersed tube tunnels under siltation loads. Summary of the invention

[0004] The present invention aims to provide a method, system and medium for calculating the settlement of an immersed tube tunnel under siltation load, so as to improve the calculation accuracy of the settlement of an immersed tube tunnel caused by siltation.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] In a first aspect, an embodiment of the present invention provides a method for calculating the settlement of an immersed tube tunnel under a siltation load, the method comprising the following steps:

[0007] S100, obtaining stress-deformation characteristics of the immersed tube tunnel, making basic assumptions based on the stress-deformation characteristics of the immersed tube tunnel, determining the cyclic form of the siltation load based on the basic assumptions, and obtaining a calculation expression of the siltation load changing with time;

[0008] S200, based on Terzaghi's one-dimensional consolidation theory differential equation, calculates the nonlinear consolidation settlement of the underlying foundation soil layer caused by siltation load; through the compression modulus, drainage distance, consolidation coefficient and cycle period of the foundation soil layer, combined with Taylor expansion, the calculation expression of foundation settlement changing with time is obtained;

[0009] S300, determining the bending moment and shear force of the sunken tube tunnel under the Timoshenko beam model, and determining the deflection of the sunken tube tunnel under different desilting frequencies based on the bending moment and shear force of the Timoshenko beam model;

[0010] S400, determining the transfer deflection difference between adjacent pipe sections in the immersed tube tunnel based on the deflection of the immersed tube tunnel, and determining the settlement value at the left end joint of any pipe section and the settlement value at the right end joint of any pipe section according to the transfer deflection difference and the rotation angle between adjacent pipe sections in the immersed tube tunnel.

[0011] Optionally, in S200, making basic assumptions based on stress and deformation characteristics of the immersed tunnel includes:

[0012] Constructing a flexible beam model of the immersed tube tunnel based on the stress-deformation characteristics;

[0013] Assuming that the immersed tube tunnel is placed on a Vlasov two-parameter foundation, the soil stiffness is set to be a constant or a function that varies with the depth of the foundation; wherein the Vlasov two-parameter foundation is continuous and its stiffness varies with depth;

[0014] It is assumed that the sedimentation load changes with time in a cyclical manner;

[0015] The deformation of the pipe segment is modeled by a dislocation deformation mode, wherein the deformation of the pipe segment includes bending deformation and shear deformation.

[0016] Optionally, the calculation expression of the siltation load changing with time is:

[0017]

[0018] Where q(t) is the sedimentation load in any time period, t is the loading duration in any time period; Q0 is the initial load; α t is the accumulated silt load that increases linearly with time, α is the accumulation rate; ΔL is the load reduction caused by each dredging event; represents the number of desilting operations completed within time t, Indicates rounding down; T q is the desilting cycle, the subscript q represents the number of the desilting cycle, and q is a positive integer. It indicates a specific desilting cycle, and the calculation expression of the desilting cycle is:

[0019]

[0020] Among them, n is the number of dredging times in a year, that is, the dredging frequency.

[0021] Optionally, in S200, the calculation expression of the change of foundation settlement over time is obtained by combining the compression modulus, drainage distance, consolidation coefficient and cycle period of the foundation soil layer with Taylor expansion, including:

[0022] The consolidation coefficient of the foundation c v Considered as constant, the Terzaghi one-dimensional consolidation theory differential equation is introduced:

[0023]

[0024] Among them, c v , z, u are the consolidation coefficient of the foundation, soil depth, and excess pore water pressure, respectively, and f(t) is the load loading rate;

[0025] According to the orthogonal relationship of trigonometric functions and Laplace inverse transformation, referring to the analytical solution of one-dimensional nonlinear consolidation of soil under continuous drainage boundary conditions, the foundation settlement S(t) at time t is calculated by the following formula:

[0026]

[0027] Where A=H / E S , B = 2 / M; H is the drainage distance; E S is the compression modulus of the foundation; M = (2a-1)π / 2, a is a positive integer; N is the number of complete load cycles; T m1 (t), T m2 (t) is the time function to be calculated, m is the index of the summation; T q is the load cycle period; i, j are the accumulated indexes; βT q The adjustment factor for the time interval is used to scale the time offset of the accumulated item.

[0028] Optionally, in S300, the calculation method for determining the deformation of the pipe segment under different dredging frequencies based on the bending moment expression and the shear force expression of the Timoshenko beam model includes:

[0029] Determine the cross-sectional rotation angle of the beam based on the deflection and shear strain of the beam, and determine the bending moment of the Timoshenko beam model that varies with position based on the cross-sectional rotation angle, elastic modulus and moment of inertia of the beam;

[0030] The shear strain of the beam is determined based on the deflection, section rotation angle and shear coefficient of the beam, and the shear force of the Timoshenko beam model with position variation is determined based on the shear strain, shear modulus and effective area of ​​the beam;

[0031] The deflection of the immersed tunnel is obtained based on the bending moment and shear force of the Timoshenko beam model.

[0032] Optionally, the deflection of the immersed tunnel is calculated by the following formula:

[0033]

[0034] Where, s is the deflection of the immersed tunnel, T k is the prestress generated during the construction of the immersed tube tunnel; EI and GA are the bending stiffness and shear stiffness of the tube segment, respectively; K is the curvature of the neutral axis; ds / dx is the rotation angle of the neutral axis, i.e., θ. For the turning angle, is the cross-sectional shear angle caused by shear deformation, i.e., γ, f s is the non-uniform distribution coefficient of cross-sectional shear stress; α, β and γ are all intermediate quantities; P(t) is the load.

[0035] Optionally, the load expression is:

[0036] P(t) = q(t)·B;

[0037] Among them, q(t) is the sedimentation load, B is the transverse width of the pipe segment;

[0038] The expression of the deflection of the right end of the pipe segment is:

[0039]

[0040] Among them, s0 is the initial deflection; θ0 is the initial rotation angle; M0 is the initial bending moment; Q0 is the initial shear force;

[0041] The bending moment of the immersed tube tunnel is obtained based on the bending moment of the Timoshenko beam model and the deflection of the right end of the tube segment;

[0042] The bending moment expression of immersed tube tunnel is:

[0043]

[0044] According to the relationship between bending moment and shear force, the shear force of the immersed tube tunnel is obtained;

[0045] The shear force expression of immersed tube tunnel is:

[0046]

[0047] Among them, M(x) and Q(x) are the bending moment and shear force of the immersed tube tunnel, respectively.

[0048] Optionally, in S400, determining the settlement value at the left end joint of any pipe segment and the settlement value at the right end joint of any pipe segment according to the transfer deflection difference and the rotation angle between adjacent pipe segments of the immersed tube tunnel includes:

[0049] The transfer deflection difference Δs and rotation angle Δθ between adjacent tube segments in the immersed tube tunnel are calculated by the following formula:

[0050] Δs=Q(i) / k j ;

[0051] Δθ=M(i) / k W ;

[0052] Where Δs is the transfer deflection difference between adjacent segments of the immersed tunnel, Δθ is the rotation angle between adjacent segments of the immersed tunnel, Q(i) and M(i) are the shear force between the i-th segment and the i-1-th segment and the bending moment of the immersed tunnel, respectively, and k j and k w are the shear stiffness and bending stiffness of the joint respectively;

[0053] The sum of the settlement value at the right end of the previous pipe section and the transfer deflection difference between the adjacent joints of the previous pipe section is taken as the settlement value at the left end joint of the current pipe section, and the sum of the settlement value at the left end of the pipe section and the deflection value of the pipe section is taken as the settlement value at the right end joint of the current pipe section.

[0054] In a second aspect, an embodiment of the present invention provides a system for calculating the settlement of an immersed tunnel under siltation load, the system comprising:

[0055] at least one processor;

[0056] at least one memory for storing at least one program;

[0057] When the at least one program is executed by the at least one processor, the at least one processor implements the method for calculating the settlement of an immersed tube tunnel under siltation load as described in any one of the above.

[0058] In a third aspect, an embodiment of the present invention provides a computer-readable storage medium storing a program executable by a processor, wherein the program executable by the processor is used to execute the method for calculating the settlement of an immersed tube tunnel under siltation load as described in any one of the above when executed by the processor.

[0059] The beneficial effects of the present invention are as follows: the present invention discloses a method, system and medium for calculating the settlement of an immersed tube tunnel under siltation load, based on the Vlasov dual-parameter foundation model and the Timoshenko beam model, by considering the continuity of the foundation soil and the shear deformation of the immersed tube structure, a calculation method capable of accurately predicting the long-term settlement of an immersed tube tunnel under siltation cyclic load is established. The present invention is easy to operate and cost-effective, and helps monitoring personnel optimize the design and management of immersed tube tunnels, make plans for the settlement deformation of immersed tube tunnels in advance, and improve their long-term safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0061] Figure 1 1 is a flow chart of a method for calculating the settlement of an immersed tube tunnel under siltation load in an embodiment of the present invention;

[0062] Figure 2 It is a function diagram of the variation trend of the sedimentation load over time in the present invention;

[0063] Figure 3 It is a schematic diagram of an immersed tube tunnel in a certain engineering example provided by an embodiment of the present invention;

[0064] Figure 4 yes Figure 3 Curve diagram of the change of sedimentation load on the medium immersed tube tunnel;

[0065] Figure 5 yes Figure 3 Comparison chart of model calculation and measured data of medium immersed tube tunnel;

[0066] Figure 6 yes Figure 3 Comparison chart of the difference between the calculated and measured data of the medium immersed tube tunnel model;

[0067] Figure 7 It is a structural diagram of a settlement calculation system for an immersed tube tunnel under siltation load in an embodiment of the present invention. DETAILED DESCRIPTION

[0068] The following will be combined with the embodiments and drawings to clearly and completely describe the concept, specific structure and technical effects of the present invention, so as to fully understand the purpose, scheme and effect of the present invention. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0069] In order to solve the technical problems in the background technology, the embodiment provided by the present invention analyzes the stress and deformation of the tunnel joint based on the Timoshenko beam model, and carries out joint stress analysis based on the Timoshenko beam model, thereby improving the accuracy of predicting the settlement deformation of the immersed tube tunnel, thereby improving the safety and reliability of the long-term operation of the tunnel.

[0070] See also Figure 1 , Figure 1 The present invention provides a method for calculating the settlement of an immersed tube tunnel under siltation load, the method comprising the following steps:

[0071] S100, obtaining stress-deformation characteristics of the immersed tube tunnel, making basic assumptions based on the stress-deformation characteristics of the immersed tube tunnel, determining the cyclic form of the siltation load based on the basic assumptions, and obtaining a calculation expression of the siltation load changing with time;

[0072] S200, based on Terzaghi's one-dimensional consolidation theory differential equation, calculates the nonlinear consolidation settlement of the underlying foundation soil layer caused by siltation load; through the compression modulus, drainage distance, consolidation coefficient and cycle period of the foundation soil layer, combined with Taylor expansion, the calculation expression of foundation settlement changing with time is obtained;

[0073] S300, determining the bending moment and shear force of the sunken tube tunnel under the Timoshenko beam model, and determining the deflection of the sunken tube tunnel under different desilting frequencies based on the bending moment and shear force of the Timoshenko beam model;

[0074] Specifically, after determining the bending moment and shear force of the immersed tube tunnel under the Timoshenko beam model, the deflection under different desilting frequencies is determined, and the deformation of the pipe segment of the immersed tube tunnel is obtained.

[0075] S400, determining the transfer deflection difference between adjacent pipe sections in the immersed tube tunnel based on the deflection of the immersed tube tunnel, and determining the settlement value at the left end joint of any pipe section and the settlement value at the right end joint of any pipe section according to the transfer deflection difference and the rotation angle between adjacent pipe sections in the immersed tube tunnel.

[0076] In the embodiment provided by the present invention, based on the stress and deformation characteristics of the flexible immersed tube tunnel under load, the tunnel pipe segment is simplified into a Timoshenko beam, placed on the Vlasov dual-parameter foundation model, and the continuity of the foundation soil and the enhancement of the soil stiffness are taken into account. The invention further takes into account the bending and shear deformation of the pipe segment, adopts the dislocation deformation mode to model the deformation of the pipe segment, and derives the calculation formula for vertical settlement. Combined with the actual working conditions, the settlement value at the left end joint of each pipe segment and the settlement value at the right end joint of each pipe segment can be determined according to the transfer deflection difference and rotation angle between adjacent pipe segments of the immersed tube tunnel. The invention is easy to operate, has high economic benefits, can provide strong support for tunnel design and management, and help monitoring personnel to timely predict the settlement deformation of the immersed tube tunnel, thereby improving the safety and reliability of the long-term operation of the tunnel.

[0077] In some embodiments, in S200, making basic assumptions based on the stress and deformation characteristics of the immersed tunnel includes:

[0078] Constructing a flexible beam model of the immersed tube tunnel based on the stress-deformation characteristics;

[0079] Specifically, the immersed tube tunnel behaves as a flexible structure under load, so the immersed tube tunnel can be simplified as a flexible beam and the rigidity effect of the structure can be ignored;

[0080] Assuming that the immersed tube tunnel is placed on a Vlasov two-parameter foundation, the soil stiffness is set to be a constant or a function that varies with the depth of the foundation; wherein the Vlasov two-parameter foundation is continuous and its stiffness varies with depth;

[0081] Specifically, the immersed tunnel is placed on the Vlasov two-parameter foundation, assuming that the foundation soil is continuous and its stiffness varies with depth. The soil stiffness can be considered as a constant or a function that varies with the foundation depth;

[0082] It is assumed that the sedimentation load changes with time in a cyclical manner;

[0083] In this step, it is assumed that the distribution of the sedimentation load follows the periodic characteristics of time variation, and the variation of the sedimentation load is assumed to conform to the typical cycle law of the sedimentation load;

[0084] The deformation of the pipe segment is modeled by a dislocation deformation mode, wherein the deformation of the pipe segment includes bending deformation and shear deformation.

[0085] Specifically, the deformation of the pipe segment mainly manifests as bending deformation and shear deformation, and the deformation of the pipe segment can be modeled by the dislocation deformation mode.

[0086] In some embodiments, the calculation expression of the siltation load changing with time is:

[0087]

[0088] Where q(t) is the sedimentation load in any time period, t is the loading duration in any time period; Q0 is the initial load; α t is the accumulated silt load that increases linearly with time, α is the accumulation rate; ΔL is the load reduction caused by each dredging event; represents the number of desilting operations completed within time t, Indicates rounding down; T q is the desilting cycle, the subscript q represents the number of the desilting cycle, and q is a positive integer. It indicates a specific desilting cycle, and the calculation expression of the desilting cycle is:

[0089]

[0090] Among them, n is the number of dredging times in a year, that is, the dredging frequency.

[0091] In some embodiments, in S200, the calculation expression of the change of foundation settlement over time is obtained by combining the compression modulus, drainage distance, consolidation coefficient and cycle period of the foundation soil layer with the Taylor expansion, including:

[0092] The consolidation coefficient of the foundation c v Considered as constant, the Terzaghi one-dimensional consolidation theory differential equation is introduced:

[0093]

[0094] Among them, c v , z, u are the consolidation coefficient of the foundation, soil depth, and excess pore water pressure, respectively, and f(t) is the load loading rate;

[0095] According to the orthogonal relationship of trigonometric functions and Laplace inverse transformation, referring to the analytical solution of one-dimensional nonlinear consolidation of soil under continuous drainage boundary conditions, the foundation settlement S(t) at time t is calculated by the following formula:

[0096]

[0097] Where A=H / E S , B = 2 / M; H is the drainage distance; E S is the compression modulus of the foundation; M = (2a-1)π / 2, a is a positive integer; N is the number of complete load cycles; T m1 (t), T m2 (t) is the time function to be calculated, m is the index of the summation; T q is the load cycle period; i, j are the accumulated indexes; βT qThe adjustment factor for the time interval is used to scale the time offset of the accumulated item.

[0098] In some embodiments, in S300, the calculation method for determining the deformation of the pipe segment under different dredging frequencies based on the bending moment expression and the shear force expression of the Timoshenko beam model includes:

[0099] Determine the cross-sectional rotation angle of the beam based on the deflection and shear strain of the beam, and determine the bending moment of the Timoshenko beam model that varies with position based on the cross-sectional rotation angle, elastic modulus and moment of inertia of the beam;

[0100] The shear strain of the beam is determined based on the deflection, section rotation angle and shear coefficient of the beam, and the shear force of the Timoshenko beam model with position variation is determined based on the shear strain, shear modulus and effective area of ​​the beam;

[0101] The deflection of the immersed tunnel is obtained based on the bending moment and shear force of the Timoshenko beam model.

[0102] In some embodiments, the deflection of the immersed tunnel is calculated by the following formula:

[0103]

[0104]

[0105] Where, s is the deflection of the immersed tunnel, T k is the prestress generated during the construction of the immersed tube tunnel; EI and GA are the bending stiffness and shear stiffness of the tube segment, respectively; K is the curvature of the neutral axis; ds / dx is the rotation angle of the neutral axis, i.e., θ. For the turning angle, is the cross-sectional shear angle caused by shear deformation, i.e., γ, f s is the non-uniform distribution coefficient of cross-sectional shear stress; α, β and γ are all intermediate quantities; P(t) is the load.

[0106] In some embodiments, the load is expressed as:

[0107] P(t) = q(t)·B;

[0108] Among them, q(t) is the sedimentation load, B is the transverse width of the pipe segment;

[0109] The expression of the deflection of the right end of the pipe segment is:

[0110]

[0111] Among them, s0 is the initial deflection; θ0 is the initial rotation angle; M0 is the initial bending moment; Q0 is the initial shear force;

[0112] The bending moment of the immersed tube tunnel is obtained based on the bending moment of the Timoshenko beam model and the deflection of the right end of the tube segment;

[0113] The bending moment expression of immersed tube tunnel is:

[0114]

[0115] According to the relationship between bending moment and shear force, the shear force of the immersed tube tunnel is obtained;

[0116] The shear force expression of immersed tube tunnel is:

[0117]

[0118] Among them, M(x) and Q(x) are the bending moment and shear force of the immersed tube tunnel, respectively.

[0119] In some embodiments, in S400, determining the settlement value at the left end joint of any pipe segment and the settlement value at the right end joint of any pipe segment according to the transfer deflection difference and the rotation angle between adjacent pipe segments of the immersed tube tunnel includes:

[0120] The transfer deflection difference Δs and rotation angle Δθ between adjacent tube segments in the immersed tube tunnel are calculated by the following formula:

[0121] Δs=Q(i) / k j ;

[0122] Δθ=M(i) / k W ;

[0123] Where Δs is the transfer deflection difference between adjacent segments of the immersed tunnel, Δθ is the rotation angle between adjacent segments of the immersed tunnel, Q(i) and M(i) are the shear force between the i-th segment and the i-1-th segment and the bending moment of the immersed tunnel, respectively, and k j and k w are the shear stiffness and bending stiffness of the joint respectively;

[0124] The settlement value at the left end joint of the pipe segment is calculated by the following formula:

[0125] W i- =W (i-1)+ +Δs (i-1) ;

[0126] Among them, W i- is the settlement value at the left end joint of the i-th pipe segment, W (i-1)+ is the settlement value at the right end joint of the i-1th pipe segment, Δs (i-1) is the difference in transfer deflection between the adjacent joints of the i-th pipe segment and the i-1-th pipe segment;

[0127] The settlement value at the right end joint of the pipe segment is calculated by the following formula:

[0128] W i+ =W i- +s i ;

[0129] Among them, W i+ is the settlement value at the right end joint of the i-th pipe segment, s i is the deflection value of the ith pipe segment.

[0130] It should be noted that if Δs is a positive number, it means that the next pipe section is settled relative to the previous pipe section, and if Δs is a negative number, it means that the next pipe section is lifted relative to the previous pipe section. If Δθ is a positive number, it means that the pipe section rotates clockwise, and if Δθ is a negative number, it means that the pipe section rotates counterclockwise. The settlement value at the left end joint of any pipe section is the sum of the settlement value at the right end of the previous pipe section and the transfer deflection difference between the adjacent joints of the previous pipe section: then the settlement value at the right end joint of any pipe section is the sum of the settlement value at the left end of the pipe section and the deflection value of the pipe section.

[0131] The following is a specific experiment to illustrate the settlement calculation method of the immersed tube tunnel provided by the present invention:

[0132] In a certain immersed tube tunnel, the tunnel length is 1019.97m, the total length of the immersed tube section is 420m, and the immersed tube consists of 5 sections, which are marked as E1 to E5 (85m+80m+85m×3) from north to south. Figure 3 As shown. The maximum flow rate of the river water is 1.2-1.3m / s, the average flow rate is 0.36-0.37m / s, the mud and sand content is large, and the siltation is serious. The measured siltation intensity is 3cm / d. These mud and sand are mainly brought in from the open sea by the rising tide, that is, mud and sand backflow. In order to prevent the phenomenon of excessive settlement of the pipe section due to siltation, the tunnel management department carries out silt removal twice a year, and each silt removal takes about half a month.

[0133] According to step S100, it is assumed that the siltation load is a trapezoidal cyclic function such as Figure 2 As shown, the relevant parameters are determined as α=0.5, β=1.0, γ=0.9, and the silt removal frequency is discussed twice a year, T=182.5d, d represents the number of days, and the maximum value of the cyclic load function q(tu)=16.425KPa can be obtained according to the measured siltation intensity. According to the Timoshenko beam model (VT settlement model) of the Vlasov dual-parameter foundation proposed by the present invention, the basic parameters of the calculation model are obtained.

[0134] According to step S200, the nonlinear consolidation settlement of the underlying foundation soil layer caused by this is calculated based on the Terzaghi one-dimensional consolidation theory differential equation. The joint is made of rubber material. Within the range of the working water pressure range, the bending stiffness ratio of the joint to the pipe body is 1 / 600, the shear stiffness ratio is 1 / 50, and the joint bending stiffness k is taken. w =3.2×106kN·m / rad, shear stiffness k j =1.1×106kN / m, the shear correction coefficient fs of the beam section is taken as 2.0.

[0135]

[0136] The changes in sedimentation load on a certain immersed tube tunnel section are as follows: Figure 4 shown.

[0137] According to step S300, for the calculation model that only considers the one-dimensional nonlinear consolidation settlement theory of the underlying soil layer of the riverbed (one-dimensional settlement model), the bending moment of the immersed tube tunnel can be calculated by combining the bending moment expression M(x) of the Timoshenko beam model with the deflection expression s of the right end of the pipe segment:

[0138]

[0139] According to the relationship between bending moment and shear force, the shear force of the immersed tube tunnel is obtained as:

[0140]

[0141] Through MATLAB fitting, we can get the curve of the vertical displacement of the pipe joint section changing with time, as shown in Figure 5 As shown, compared with the one-dimensional settlement model, the settlement model used in the present invention is more consistent with the measured settlement.

[0142] According to step S400, the settlement value W at the left end joint of any pipe segment i- is the settlement value W at the right end of the previous pipe segment (i-1)+ and the transfer deflection difference Δs between the adjacent joints of the previous pipe section (i-1) sum:

[0143] W i- =W (i-1)+ +Δs (i-1) ;

[0144] At the same time, the settlement value W at the right end joint of any pipe segment i+ is the settlement value W at the left end of the pipe segment i- and the deflection value of the pipe segment s i sum:

[0145] W i+ =W i-+s i ;

[0146] The settlement value of the VT model is obtained by calculation. The settlement difference between the VT model and the measured data is the same as the difference between the one-dimensional settlement model and the measured data, such as Figure 6 Compared with the one-dimensional settlement model, the settlement model used in the present invention has a smaller error and is closer to the measured data.

[0147] In summary, the calculation results of the Timoshenko beam model based on the Vlasov dual-parameter foundation model and the joint deformation are well matched with the measured data, and the settlement results can be well predicted by calculation.

[0148] and Figure 1 Corresponding to the method, refer to Figure 7 The embodiment of the present invention provides a settlement calculation system for an immersed tunnel under siltation load, comprising:

[0149] at least one processor;

[0150] at least one memory for storing at least one program;

[0151] When the at least one program is executed by the at least one processor, the at least one processor implements the above method.

[0152] It can be seen that the contents of the above method embodiments are all applicable to the present system embodiments, the functions specifically implemented by the present system embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0153] In addition, an embodiment of the present invention further discloses a computer program product or a computer program, which is stored in a computer-readable storage medium. A processor of a computer device can read the computer program from a computer-readable storage medium, and the processor executes the computer program, so that the computer device executes the above method. Similarly, the contents of the above method embodiment are all applicable to the storage medium embodiment, and the functions specifically implemented by the storage medium embodiment are the same as those of the above method embodiment, and the beneficial effects achieved are also the same as those achieved by the above method embodiment.

[0154] It will be appreciated by those skilled in the art that all or some of the methods disclosed above, the system can be implemented as software, firmware, hardware and appropriate combinations thereof. Some physical components or all physical components can be implemented as software executed by a processor, such as a central processing unit, a digital signal processor or a microprocessor, or implemented as hardware, or implemented as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, and the computer-readable medium can include a computer storage medium (or a non-transitory medium) and a communication medium (or a temporary medium). As known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disk (DVD) or other optical disk storage, magnetic cassettes, magnetic tapes, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically embodies computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0155] The above is a specific description of the preferred implementation of the present disclosure, but the present disclosure is not limited to the above-mentioned implementation mode. Technical personnel familiar with the field can also make various equivalent deformations or substitutions without violating the spirit of the present disclosure. These equivalent deformations or substitutions are all included in the scope defined by the claims of the present disclosure.

Claims

1. A method for calculating the settlement of an immersed tunnel under siltation load, characterized in that: The method comprises the following steps: S100, obtaining stress-deformation characteristics of the immersed tube tunnel, making basic assumptions based on the stress-deformation characteristics of the immersed tube tunnel, determining the cyclic form of the siltation load based on the basic assumptions, and obtaining a calculation expression of the siltation load changing with time; S200, based on Terzaghi's one-dimensional consolidation theory differential equation, calculates the nonlinear consolidation settlement of the underlying foundation soil layer caused by siltation load; through the compression modulus, drainage distance, consolidation coefficient and cycle period of the foundation soil layer, combined with Taylor expansion, the calculation expression of foundation settlement changing with time is obtained; S300, determining the bending moment and shear force of the sunken tube tunnel under the Timoshenko beam model, and determining the deflection of the sunken tube tunnel under different desilting frequencies based on the bending moment and shear force of the Timoshenko beam model; S400, determining the transfer deflection difference between adjacent pipe sections in the immersed tube tunnel based on the deflection of the immersed tube tunnel, and determining the settlement value at the left end joint of any pipe section and the settlement value at the right end joint of any pipe section according to the transfer deflection difference and the rotation angle between adjacent pipe sections in the immersed tube tunnel.

2. The method for calculating the settlement of an immersed tunnel under siltation load according to claim 1, characterized in that: In S200, the basic assumptions made based on the stress and deformation characteristics of the immersed tube tunnel include: Constructing a flexible beam model of the immersed tube tunnel based on the stress-deformation characteristics; Assuming that the immersed tube tunnel is placed on a Vlasov two-parameter foundation, the soil stiffness is set to be a constant or a function that varies with the depth of the foundation; wherein the Vlasov two-parameter foundation is continuous and its stiffness varies with depth; It is assumed that the sedimentation load changes with time in a cyclical manner; The deformation of the pipe segment is modeled by a dislocation deformation mode, wherein the deformation of the pipe segment includes bending deformation and shear deformation.

3. The method for calculating the settlement of an immersed tunnel under siltation load according to claim 2, characterized in that: The calculation expression of the sedimentation load changing with time is: Where q(t) is the sedimentation load in any time period, t is the loading duration in any time period; Q0 is the initial load; α t is the accumulated silt load that increases linearly with time, α is the accumulation rate; ΔL is the load reduction caused by each dredging event; represents the number of desilting operations completed within time t, Indicates rounding down; T q is the desilting cycle, the subscript q represents the number of the desilting cycle, and the calculation expression of the desilting cycle is: Among them, n is the number of dredging times in a year, that is, the dredging frequency.

4. The method for calculating the settlement of an immersed tunnel under siltation load according to claim 3 is characterized in that: In S200, the calculation expression of the change of foundation settlement over time is obtained by combining the compression modulus, drainage distance, consolidation coefficient and cycle period of the foundation soil layer with the Taylor expansion, including: The consolidation coefficient c of the foundation v Considered as constant, the Terzaghi one-dimensional consolidation theory differential equation is introduced: Among them, c v , z, u are the consolidation coefficient of the foundation, soil depth, and excess pore water pressure, respectively, and f(t) is the load loading rate; According to the orthogonal relationship of trigonometric functions and Laplace inverse transformation, referring to the analytical solution of one-dimensional nonlinear consolidation of soil under continuous drainage boundary conditions, the foundation settlement S(t) at time t is calculated by the following formula: Where A=H / E S , B = 2 / M; H is the drainage distance; E S is the compression modulus of the foundation; M = (2a-1)π / 2, a is a positive integer; N is the number of complete load cycles; T m1 (t), T m2 (t) is the time function to be calculated, m is the index of the summation; T q is the load cycle period; i, j are the accumulated indexes; βT q The adjustment factor for the time interval is used to scale the time offset of the accumulated item.

5. The method for calculating the settlement of an immersed tunnel under siltation load according to claim 4, characterized in that: In S300, the calculation method for determining the deformation of the pipe segment under different dredging frequencies based on the bending moment expression and the shear force expression of the Timoshenko beam model includes: Determine the cross-sectional rotation angle of the beam based on the deflection and shear strain of the beam, and determine the bending moment of the Timoshenko beam model that varies with position based on the cross-sectional rotation angle, elastic modulus and moment of inertia of the beam; The shear strain of the beam is determined based on the deflection, section rotation angle and shear coefficient of the beam, and the shear force of the Timoshenko beam model with position variation is determined based on the shear strain, shear modulus and effective area of ​​the beam; The deflection of the immersed tunnel is obtained based on the bending moment and shear force of the Timoshenko beam model.

6. The method for calculating the settlement of an immersed tunnel under siltation load according to claim 5, characterized in that: The deflection of the immersed tunnel is calculated by the following formula: Where, s is the deflection of the immersed tunnel, T k is the prestress generated during the construction of the immersed tube tunnel; EI and GA are the bending stiffness and shear stiffness of the tube segment, respectively; K is the curvature of the neutral axis; ds / dx is the rotation angle of the neutral axis, i.e., θ. For the turning angle, is the cross-sectional shear angle caused by shear deformation, i.e., γ, f s is the non-uniform distribution coefficient of cross-sectional shear stress; α, β and γ are all intermediate quantities; P(t) is the load.

7. The method for calculating the settlement of an immersed tunnel under siltation load according to claim 6, characterized in that: The expression of the load is: P(t) = q(t)·B; Among them, q(t) is the sedimentation load, B is the transverse width of the pipe segment; The expression of the deflection of the right end of the pipe segment is: Among them, s0 is the initial deflection; θ0 is the initial rotation angle; M0 is the initial bending moment; Q0 is the initial shear force; The bending moment of the immersed tube tunnel is obtained based on the bending moment of the Timoshenko beam model and the deflection of the right end of the tube segment; The bending moment expression of immersed tube tunnel is: According to the relationship between bending moment and shear force, the shear force of the immersed tube tunnel is obtained; The shear force expression of immersed tube tunnel is: Among them, M(x) and Q(x) are the bending moment and shear force of the immersed tube tunnel, respectively.

8. The method for calculating the settlement of an immersed tunnel under siltation load according to claim 7, characterized in that: In S400, determining the settlement value at the left end joint of any pipe segment and the settlement value at the right end joint of any pipe segment according to the transfer deflection difference and the rotation angle between adjacent pipe segments of the immersed tube tunnel includes: The transfer deflection difference Δs and rotation angle Δθ between adjacent tube segments in the immersed tube tunnel are calculated by the following formula: Δs=Q(i) / kj; Δθ=M(i) / kW; Where Δs is the transfer deflection difference between adjacent segments of the immersed tunnel, Δθ is the rotation angle between adjacent segments of the immersed tunnel, Q(i) and M(i) are the shear force between the i-th segment and the i-1-th segment and the bending moment of the immersed tunnel, respectively, and k j and k w are the shear stiffness and bending stiffness of the joint respectively; The sum of the settlement value at the right end of the previous pipe section and the transfer deflection difference between the adjacent joints of the previous pipe section is taken as the settlement value at the left end joint of the current pipe section, and the sum of the settlement value at the left end of the pipe section and the deflection value of the pipe section is taken as the settlement value at the right end joint of the current pipe section.

9. A settlement calculation system for an immersed tunnel under siltation load, characterized in that: The system comprises: at least one processor; at least one memory for storing at least one program; When the at least one program is executed by the at least one processor, the at least one processor implements the method for calculating the settlement of an immersed tunnel under siltation load as described in any one of claims 1 to 8.

10. A computer-readable storage medium storing a program executable by a processor, characterized in that: The processor-executable program is used to perform the method according to any one of claims 1 to 8 when executed by the processor.

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