Shield tunnel segment structure prototype test load equivalence method considering joint influence

Abstract

The invention discloses a shield tunnel segment structure prototype test load equivalence method considering joint influence, and belongs to the technical field of shield tunnel segment structure prototype tests, and the method comprises the following steps: respectively building two beam spring finite element models considering joint influence in ANSYS software; five actual load parameters actually borne by the shield tunnel segmental lining structure are substituted into a beam spring finite element model, and actual axial force, actual bending moment and actual displacement are obtained; substituting the three equivalent load parameters into another beam spring finite element model to obtain an equivalent axial force, an equivalent bending moment and an equivalent displacement; the average value relative error between the equivalent axial force and the actual axial force, the similarity coefficient between the equivalent bending moment and the actual bending moment and the similarity coefficient between the equivalent displacement and the actual displacement are made to meet the conditions, and the final three equivalent load parameters are determined. According to the method, the calculation precision and the equivalent precision are remarkably improved, and the equivalent load in the test better conforms to the actual load.

Description

Technical Field

[0001] The invention belongs to the technical field of prototype test of shield tunnel segment structure, and specifically relates to a load equivalence method for prototype test of shield tunnel segment structure, and in particular to a load equivalence method for prototype test of shield tunnel segment structure taking into account the influence of joints. Background Art

[0002] As an important transportation infrastructure, shield tunnels have been continuously developing towards ultra-large diameters, ultra-high water pressures and deep burial depths in recent years. In this process, a lot of analysis work on structural mechanical behavior and bearing performance is required. The prototype test of shield tunnel segment structure is the most direct and effective method to study the mechanical properties of segment structure. It can simulate the stress, displacement and damage of segment structure under different load conditions, so as to provide reliable technical advice and support for the design and construction of shield tunnel structure. In the prototype test of shield tunnel segment structure, before conducting the test, it is necessary to first clarify the corresponding relationship between the equivalent load of the prototype structure test and the actual load, and convert the complex actual load pattern into an equivalent load pattern that is convenient for test loading.

[0003] There are five actual load parameters in the actual load mode of shield tunnel segment lining structure, as shown in the attached figure. Figure 1 As shown in the figure, namely, water pressure Pw, vertical earth pressure P, lateral upper earth pressure e1, lateral lower earth pressure e2 and stratum resistance Pk; there are only three equivalent load parameters in the equivalent load mode in the prototype test of shield tunnel segment structure, as shown in the figure. Figure 2 As shown in the figure, the water pressure Pew, the main tension P1 and the secondary tension P2, that is, the five actual load parameters actually borne by the shield tunnel segment lining structure in the prototype test of the shield tunnel segment structure are equivalent to the three equivalent load parameters in the prototype test of the shield tunnel segment structure. This method is the load equivalence method of the prototype test of the shield tunnel segment structure.

[0004] The traditional prototype test load equivalence method for shield tunnel segment structure has the following defects: the tunnel structure is regarded as a homogeneous circular ring structure, the influence of the segment joint is not considered, the segment structure is regarded as a homogeneous elastic circular ring, and a load equivalence conversion relationship is established through a series of theoretical derivations, the complex actual load mode is converted into an equivalent load mode that is convenient for test loading, and the load coefficient is used to increase the influence of the load simulation joint, so that the loading mode of the simulation test is not in line with the actual situation, and the actual situation that the joint structure is weaker than other structural parts under the structural load cannot be accurately simulated, so the test is not rigorous and accurate enough; when the number of segment joints is small, the prototype test load equivalence method of the traditional shield tunnel segment structure has a high calculation accuracy, but for the large-section segment lining structure, the cross-section is large and the number of joints is often more than 8 to 10, the weakening effect of the joint on the overall structure is more obvious, and the influence on the structure is significantly increased, and the prototype test load equivalence method of the traditional shield tunnel segment structure has a problem of significantly reduced calculation accuracy. Summary of the invention

[0005] The purpose of the present invention is to solve the above-mentioned problem and to provide a prototype test load equivalence method for shield tunnel segment structure taking into account the influence of joints, which can significantly improve the calculation accuracy for large-section segment lining structures with a large number of joints.

[0006] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0007] A load equivalence method for prototype test of shield tunnel segment structure considering the influence of joints comprises the following steps:

[0008] Step 1, respectively establish the following two models in ANSYS software: a first beam spring finite element model including five load parameters, namely water pressure Pw, vertical earth pressure P, lateral upper earth pressure e1, lateral lower earth pressure e2 and stratum resistance Pk; a second beam spring finite element model including three load parameters, namely water pressure Pew, main tension P1 and auxiliary tension P2; the segments in the first beam spring finite element model and the second beam spring finite element model are all beams and are simulated by Beam3 unit to consider the plastic damage characteristics of the material; the joints are all springs and are simulated by COMBIN39 unit, and the nonlinear stiffness of the joints is used as the input parameter of the spring to consider the iterative algorithm of the bending stiffness of the joints; wherein ANSYS software is a large-scale general finite element analysis software developed by ANSYS Corporation of the United States; BEAM3 unit is a uniaxial unit that can withstand axial tension, compression and bending, and is a two-dimensional elastic beam unit; COMBIN39 unit is called nonlinear spring unit, which is a nonlinear unidirectional unit with a generalized force-displacement curve; these are all prior arts;

[0009] Step 2, substituting five actual load parameters of the water pressure Pw, vertical earth pressure P, lateral upper earth pressure e1, lateral lower earth pressure e2 and stratum resistance Pk actually exerted on a shield tunnel segment lining structure into the first beam-spring finite element model to obtain the actual axial force, actual bending moment and actual displacement of the segment lining structure;

[0010] Step 3, obtain the three equivalent load parameters of water pressure Pew, main tension P1 and auxiliary tension P2 according to the general method (i.e., traditional method), substitute them into the second beam spring finite element model, and obtain the equivalent axial force, equivalent bending moment and equivalent displacement of the segment lining structure;

[0011] Step 4, calculate (using conventional calculation methods, which can be achieved using ANSYS software) the average relative error between the equivalent axial force and the actual axial force, the similarity coefficient R1 between the equivalent bending moment and the actual bending moment, and the similarity coefficient R2 between the equivalent displacement and the actual displacement. If the average relative error is greater than 2%, or the similarity coefficient R1 is less than 0.85, or the similarity coefficient R2 is less than 0.95, then change (the change method depends on the actual calculation results, as long as there is a trend of making the average relative error smaller and the similarity coefficient R1 and the similarity coefficient R2 larger) the three equivalent load parameters of water pressure Pew, main tension P1 and auxiliary tension P2, and re-substitute them into the second beam spring finite element model to obtain new equivalent axial force, equivalent bending moment and equivalent displacement, and repeat this step until the average relative error is not greater than 2%, or the similarity coefficient R1 is not less than 0.85, or the similarity coefficient R2 is not less than 0.95, and use the corresponding water pressure Pew, main tension P1 and auxiliary tension P2 as the last three equivalent load parameters.

[0012] Preferably, in order to reduce the workload in the test preparation stage and save a lot of time, the load equivalence method for prototype test of shield tunnel segment structure considering the influence of joints further includes the following steps after step 4:

[0013] Step 5, substitute the five actual load parameters of water pressure Pw, vertical earth pressure P, lateral upper earth pressure e1, lateral lower earth pressure e2 and stratum resistance Pk actually exerted on different shield tunnel segment lining structures into the first beam-spring finite element model, repeat steps 2 to 4, and obtain three new equivalent load parameters; repeat this step to obtain multiple groups of five actual load parameters and corresponding three equivalent load parameters to form a data sample set;

[0014] Step 6: Establish a neural network model based on the data sample set obtained in step 5. The input parameter is 5, the output parameter is 3, the number of hidden layers is 3, and each hidden layer contains 8 neurons. A stable neural network model is obtained through a large amount of training.

[0015] Preferably, the number of groups of five actual load parameters and corresponding three equivalent load parameters obtained in step 5 is 100.

[0016] The beneficial effects of the present invention are:

[0017] The present invention establishes two models taking into account the influence of the pipe segment joint in the ANSYS software, and respectively calculates the average relative error between the equivalent axial force and the actual axial force, the similarity coefficient R1 between the equivalent bending moment and the actual bending moment, and the similarity coefficient R2 between the equivalent displacement and the actual displacement. Only after the conditions of "average relative error is not greater than 2%, similarity coefficient R1 is not less than 0.85, and similarity coefficient R2 is not less than 0.95" are met, the three optimized equivalent load parameters are determined, and the function of quantifying the equivalent load in the test and the actual load on the pipe segment structure is realized, and the calculation accuracy and equivalent accuracy are significantly improved, so that the equivalent load in the test is more consistent with the actual load; by calculating multiple groups of five actual load parameters and the corresponding three equivalent load parameters, a data sample set is formed, and a neural network model is established, and a large number of trainings are performed to obtain a stable neural network model. When applied, only five actual load parameters need to be input to immediately obtain the corresponding three equivalent load parameters, thereby reducing a large amount of workload in the test preparation stage, saving a large amount of time (the calculation time requirement for a set of data exceeds 24 hours), and significantly improving the test efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic diagram of an actual load mode of the shield tunnel segment lining structure according to the present invention;

[0019] Figure 2 is a schematic diagram of an equivalent load mode for a prototype test of a shield tunnel segment structure according to the present invention;

[0020] Figure 3 It is a flow chart of the load equivalence method for prototype test of shield tunnel segment structure considering the influence of joints according to the present invention;

[0021] Figure 4 It is a schematic diagram of comparison between equivalent axial force and actual axial force in the prototype test load equivalence method of shield tunnel segment structure considering the influence of joints according to the present invention;

[0022] Figure 5 It is a schematic diagram of comparison between equivalent bending moment and actual bending moment in the load equivalence method of the prototype test of the shield tunnel segment structure considering the influence of the joints according to the present invention;

[0023] Figure 6 It is a schematic diagram of comparison between equivalent displacement and actual displacement in the load equivalence method of the prototype test of the shield tunnel segment structure considering the influence of the joints according to the present invention;

[0024] Figure 7 It is a schematic diagram of a neural network model in the prototype test load equivalence method of a shield tunnel segment structure taking into account the influence of joints described in the present invention. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings:

[0026] like Figure 3 As shown, the prototype test load equivalence method of shield tunnel segment structure considering the influence of joints of the present invention comprises the following steps:

[0027] Step 1: Establish the following two models in ANSYS software: Figure 1 The first beam spring finite element model with five load parameters including water pressure Pw, vertical earth pressure P, lateral upper earth pressure e1, lateral lower earth pressure e2 and stratum resistance Pk shown in FIG. Figure 2 The second beam-spring finite element model with three load parameters of water pressure Pew, main tension force P1 and auxiliary tension force P2 shown in the figure, the tube segments in the first beam-spring finite element model and the second beam-spring finite element model are all beams and are simulated by Beam3 unit to consider the plastic damage characteristics of the material, the joints are all springs and are simulated by COMBIN39 unit, and the nonlinear stiffness of the joint is used as the input parameter of the spring to consider the iterative algorithm of the bending stiffness of the joint;

[0028] Step 2: Substitute the five actual load parameters of the water pressure Pw, vertical earth pressure P, lateral upper earth pressure e1, lateral lower earth pressure e2 and stratum resistance Pk actually received by a shield tunnel segment lining structure into the first beam-spring finite element model to obtain the actual axial force, actual bending moment and actual displacement of the segment lining structure, as shown in Figure 4 , Figure 5 and Figure 6 As shown, the actual axial force is the axial force of the actual load, the actual bending moment is the bending moment of the actual load, and the actual displacement is the displacement of the actual load;

[0029] Step 3: Obtain the three equivalent load parameters of water pressure Pew, primary tension P1 and secondary tension P2 according to the general method (i.e., traditional method), and substitute them into the second beam spring finite element model to obtain the equivalent axial force, equivalent bending moment and equivalent displacement of the segment lining structure, as shown in FIG. Figure 4 , Figure 5 and Figure 6 As shown, the equivalent axial force is the axial force of the equivalent load, the equivalent bending moment is the bending moment of the equivalent load, and the equivalent displacement is the displacement of the equivalent load;

[0030] Step 4, calculate (using conventional calculation methods, which can be achieved using ANSYS software) the average relative error between the equivalent axial force and the actual axial force, the similarity coefficient R1 between the equivalent bending moment and the actual bending moment, and the similarity coefficient R2 between the equivalent displacement and the actual displacement. If the average relative error is greater than 2%, or the similarity coefficient R1 is less than 0.85, or the similarity coefficient R2 is less than 0.95, then change (the change method depends on the actual calculation results, as long as there is a trend of making the average relative error smaller and the similarity coefficient R1 and the similarity coefficient R2 larger) the three equivalent load parameters of water pressure Pew, main tension P1 and auxiliary tension P2, and re-substitute them into the second beam spring finite element model to obtain new equivalent axial force, equivalent bending moment and equivalent displacement, and repeat this step until the average relative error is not greater than 2%, or the similarity coefficient R1 is not less than 0.85, or the similarity coefficient R2 is not less than 0.95, and use the corresponding water pressure Pew, main tension P1 and auxiliary tension P2 as the last three equivalent load parameters;

[0031] Step 5, substitute the five actual load parameters of water pressure Pw, vertical earth pressure P, lateral upper earth pressure e1, lateral lower earth pressure e2 and stratum resistance Pk actually received by different shield tunnel segment lining structures into the first beam-spring finite element model, repeat steps 2 to 4, and obtain three new equivalent load parameters; repeat this step to obtain multiple groups (preferably 100 groups) of five actual load parameters and corresponding three equivalent load parameters to form a data sample set;

[0032] Step 6: Establish a neural network model based on the data sample set obtained in step 5, such as Figure 7 As shown, the input parameter is 5, the output parameter is 3, the number of hidden layers is 3, each hidden layer contains 8 neurons, and a stable neural network model is obtained through a large amount of training.

[0033] When conducting a prototype test of a shield tunnel segment structure, if a stable neural network model has not yet been obtained (for example, it cannot be implemented because there is not enough data), the calculation is performed according to the above steps 1 to 4, and finally the three equivalent load parameters of water pressure Pew, main tension P1 and auxiliary tension P2 are obtained based on the five actual load parameters of water pressure Pw, vertical earth pressure P, lateral upper earth pressure e1, lateral lower earth pressure e2 and stratum resistance Pk. Compared with the water pressure Pew, main tension P1 and auxiliary tension P2 obtained by the traditional load equivalence method of the prototype test of the shield tunnel segment structure, the accuracy is much higher; if a stable neural network model has been obtained, the five actual load parameters of water pressure Pw, vertical earth pressure P, lateral upper earth pressure e1, lateral lower earth pressure e2 and stratum resistance Pk can be directly input into the neural network model to directly obtain the three equivalent load parameters of water pressure Pew, main tension P1 and auxiliary tension P2 with high accuracy, which is extremely efficient.

[0034] The above embodiments are only preferred embodiments of the present invention and are not limitations of the technical solutions of the present invention. Any technical solution that can be implemented on the basis of the above embodiments without creative work should be deemed to fall within the scope of protection of the patent of the present invention.

Claims

1. A prototype test load equivalence method for shield tunnel segment structure considering the influence of joints, characterized by: The following steps are involved: Step 1, respectively establish the following two models in ANSYS software: a first beam-spring finite element model including five load parameters, namely, water pressure Pw, vertical soil pressure P, lateral upper soil pressure e1, lateral lower soil pressure e2 and stratum resistance Pk; a second beam-spring finite element model including three load parameters, namely, water pressure Pew, primary tension P1 and secondary tension P2; the segments in the first beam-spring finite element model and the second beam-spring finite element model are all beams and are simulated by Beam3 units, the joints are all springs and are simulated by COMBIN39 units, and the nonlinear stiffness of the joints is used as the input parameter of the spring; Step 2, substituting the five actual load parameters of the shield tunnel segment lining structure, namely, the water pressure Pw, the vertical earth pressure P, the lateral upper earth pressure e1, the lateral lower earth pressure e2 and the stratum resistance Pk, into the first beam-spring finite element model to obtain the actual axial force, actual bending moment and actual displacement of the segment lining structure; Step 3, obtain the three equivalent load parameters of water pressure Pew, primary tension P1 and secondary tension P2 according to the general method, substitute them into the second beam spring finite element model, and obtain the equivalent axial force, equivalent bending moment and equivalent displacement of the segment lining structure; Step 4, calculate the average relative error between the equivalent axial force and the actual axial force, the similarity coefficient R1 between the equivalent bending moment and the actual bending moment, and the similarity coefficient R2 between the equivalent displacement and the actual displacement. If the average relative error is greater than 2%, or the similarity coefficient R1 is less than 0.85, or the similarity coefficient R2 is less than 0.95, then change the three equivalent load parameters of water pressure Pew, main tension P1 and auxiliary tension P2, and re-substitute them into the second beam spring finite element model to obtain new equivalent axial force, equivalent bending moment and equivalent displacement, and repeat this step until the average relative error is not greater than 2%, or the similarity coefficient R1 is not less than 0.85, or the similarity coefficient R2 is not less than 0.95, and use the corresponding water pressure Pew, main tension P1 and auxiliary tension P2 as the last three equivalent load parameters.

2. The prototype test load equivalence method for shield tunnel segment structure considering the influence of joints according to claim 1 is characterized by: The method for equivalent load of prototype test of shield tunnel segment structure considering the influence of joints further includes the following steps after step 4: Step 5, substitute the five actual load parameters of water pressure Pw, vertical earth pressure P, lateral upper earth pressure e1, lateral lower earth pressure e2 and stratum resistance Pk actually exerted on different shield tunnel segment lining structures into the first beam-spring finite element model, repeat steps 2 to 4, and obtain three new equivalent load parameters; repeat this step to obtain multiple groups of five actual load parameters and corresponding three equivalent load parameters to form a data sample set; Step 6: Establish a neural network model based on the data sample set obtained in step 5. The input parameter is 5, the output parameter is 3, the number of hidden layers is 3, and each hidden layer contains 8 neurons. A stable neural network model is obtained through training.

3. The prototype test load equivalence method for shield tunnel segment structure considering the influence of joints according to claim 2 is characterized by: In step 5, the number of groups of five actual load parameters and corresponding three equivalent load parameters is 100.

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