CN113868735A

CN113868735A - Method and device for rapidly evaluating safety of tunnel based on parametric modeling

Info

Publication number: CN113868735A
Application number: CN202111053790.6A
Authority: CN
Inventors: 李斌; 魏中华
Original assignee: Wuhan University of Technology WUT
Current assignee: Wuhan University of Technology WUT
Priority date: 2021-09-09
Filing date: 2021-09-09
Publication date: 2021-12-31
Anticipated expiration: 2041-09-09
Also published as: CN113868735B

Abstract

The invention provides a tunnel rapid safety evaluation method and a tunnel rapid safety evaluation device based on parametric modeling, which can accurately, rapidly and comprehensively reflect the safety performance of a tunnel unit, and the method comprises the following steps: step 1, discretizing; step 2, determining basic parameters; step 3, determining key parameter variables of the n-center circular tunnel section for parametric modeling, wherein the key parameter variables comprise the arc radius and the angle, and determining the position of the tunnel section; step 4, determining unit types, material parameters and real constants; step 5, drawing a tunnel section; step 6, restraining and applying load; and 7, extracting results and displaying a safety coefficient cloud chart: and recording the obtained safety coefficient result into a preset array, replacing the array for recording the magnitude of the safety coefficient value with the array for recording the magnitude of the bending moment, and displaying the safety coefficient of each unit according to the form of a bending moment diagram.

Description

Method and device for rapidly evaluating safety of tunnel based on parametric modeling

Technical Field

The invention belongs to the field of tunnel structure design, and particularly relates to a tunnel rapid safety evaluation method and device based on parametric modeling.

Background

The safety factor (factor of safety) is a coefficient used in the engineering structure design method to reflect the degree of structure safety. In the design process of the railway tunnel structure, the safety factor of the composite lining structure determines the safety of the structure, and the safety factor is higher for the same structure in different states, so that the stability of the structure is better and safer. Therefore, in order to determine the safety capability of the structure, the existing research follows the basic flow of the safety coefficient operation of the railway tunnel lining unit, namely, the safety coefficient of the tunnel lining unit is obtained by firstly utilizing finite element software for modeling, then extracting the internal force of the structure and finally utilizing calculation software or a manual operation mode.

The disadvantages of the existing safety factor determination methods include the following aspects.

1. For a certain tunnel, the modeling process cannot be used for other tunnel sections, namely command streams can only be one-to-one, so that when different tunnel structures are designed, the tunnel size can only be manually adjusted, the command streams are respectively compiled, and the problem that errors occur easily after long-term consumption is solved;

2. bending moment, axial force and shearing force need to be led out, the tensile and compression resistant state of the concrete and the large and small eccentric states of the reinforced concrete are judged manually, and then the tensile and compression resistant state and the large and small eccentric states of the reinforced concrete are led into a calculation formula to obtain a result, so that the process is complicated and the efficiency is low;

3. for the reinforced concrete lining unit, carrying out reinforcement checking calculation according to the result;

4. structural safety cannot be intuitively reflected.

Disclosure of Invention

The invention is made to solve the above problems, and aims to provide a tunnel rapid security evaluation method and device based on parametric modeling, which can accurately and rapidly obtain a security coefficient cloud chart that comprehensively reflects the security performance of a tunnel unit.

As shown in fig. 1, in order to achieve the above object, the present invention adopts the following scheme:

< method >

Step 1, discretization:

discretizing a tunnel structure system consisting of a lining and surrounding rocks into a limited number of lining units and spring units;

step 2, determining basic parameters:

determining a basic parameter value as a model input parameter according to the actual measurement data of the tunnel to be evaluated;

and 3, determining key parameter variables of the n-center circle tunnel section for parametric modeling, wherein the key parameter variables comprise the arc radius and the angle, n is more than or equal to 1, and determining the position of the tunnel section. For example, assuming that n is 4, the radius and the angle of each circular arc of the four-center circular tunnel are used as basic parameters, the radius and the angle of the circular arc are subjected to parameter assignment according to the actual railway tunnel section size, other important parameters are determined according to the triangular relation in the circular arc of the multi-center circular tunnel, and the four-center circular railway tunnel section model shown in fig. 2 is established in finite element software.

Step 4, determining unit type, material parameters and real constants:

determining a Beam unit (Beam3) of a composite lining structure of the reaction tunnel section and a rod unit (Link10) simulating the action of surrounding rocks, and defining a specific real constant according to the size of the actual size;

step 5, drawing the section of the tunnel, comprising the following substeps:

step 5-1, according to the circle center O shown in figure 2₁～O₄Sequentially inputting the circle center positions of the arcs, generating the circle center coordinates of the arcs into class 1 key points by using a 'k' command, and generating the key points at the vault positions in the same way;

step 5-2, utilizing a circle command, sequentially making arcs corresponding to the cross section of the n-center circular tunnel by taking the type 1 key points generated in the previous step as the circle center, taking r as the radius and taking alpha as the circle center, and according to the characteristic that the serial numbers of the key points on the ANSYS working interface are accumulated continuously, recording the point with the largest serial number as the type 2 key point by using a get command after the arc generation is finished in each step, and drawing the arc by taking the type 2 key point as the starting point in the process of drawing the arc each time;

5-3, using a circle command to make the center of a circle of the key point of the type 1, wherein r is a radius, and alpha/2 is an arc corresponding to the angle in sequence, repeating the operation of the step 5-2, generating the key point after each arc is finished as the key point of the type 3, dividing each arc line into two sections in parallel, and simultaneously recording the midpoint position of the arcs, thereby obtaining the starting point, the midpoint and the ending point of each arc on the half side of the n-center circle section;

5-4, deleting lines by using an 'ldele' command, then using a 'larc' command to take the key points of the type 2 and the key points of the vault position as two end points of the circular arc, taking the key points of the type 3 as important points through which the circular arc passes to make circular arcs, and sequentially connecting the connected circular arcs by using an 'lcomb' command to serve as circular arc lines 1, wherein the result is shown in fig. 3;

step 5-5, generating a complete tunnel profile map by using an 'lsymm' command to be symmetrical along the y axis;

step 5-6, "lsel" selects all lines, "size" command divides the arc line into the desired number of units, "lmesh" command performs unit division, then "nummrg" command performs node integration, avoiding the occurrence of repeated numbering in the same position;

step 5-7, selecting a point with the ordinate of 0, namely the origin of a coordinate system, by using the 'get' as a starting point, and selecting a node generated on the left side by using the 'nsel';

step 5-8, in order to avoid that a cyclic command cannot act due to disordered node numbers or the applied load is too complicated in the load applying process, defining each node by using a plurality of groups, defining a plurality of groups a as a tunnel lining unit node storage array, and a (1) as an inverted arch bottom initial point unit number;

step 5-9, executing the circular operation on the left node by using a circular command 'do', and continuously selecting the node at the position closest to the node as the node of the next numbering sequence by using a 'nnear' command from the point a (1), wherein in order to avoid the defined nodes from being repeatedly selected, the 'nsel' command excludes the defined nodes in each step;

step 5-10, selecting the node on the right side of the tunnel section, taking the node at the vault position as an initial point, and recording the nodes in the array a in sequence by circularly utilizing a 'near' command in the same way as the step 5-9 to successfully order the nodes, wherein the schematic reference numeral diagram is shown in FIG. 4;

5-11, selecting all nodes in the array a, obtaining the maximum node of the abscissa by using a get command, and calculating the collapse height of the deep and shallow buried tunnel by substituting the maximum node of the abscissa into a collapse formula;

step 5-12, selecting a Beam unit (Beam3) to successively connect each node represented by the array through an 'e' command by using a cyclic program, and simultaneously carrying out parameter assignment;

step 5-13, entering a preprocessing module, and eliminating the influence of redundant lines by using a 'lclerar' command;

step 5-14, setting a node of an outer ring rod unit end point for simulating the surrounding rock action, wherein the length of the rod unit is not influenced on the result due to structural characteristics, the radius l of the outer ring can be set to be l ═ r +1, the operation steps 5-2 to 5-10 are repeated, the node of the rod unit end point part is set to be a plurality of groups b, the distribution position of the plurality of groups b can be referred to the sequence of the figure 4 and the array a and is positioned on the outer ring of the lining unit, and the tunnel model outline graph shown in the figure 5 is obtained, wherein the inner ring corresponds to the array a and the outer ring corresponds to the array b;

step 5-15, selecting a rod unit, correspondingly connecting each node represented by the array a and the array b sequentially through an 'e' command by using a cyclic program, and simultaneously carrying out parameter assignment, wherein the result is shown in figure 6, and completing parametric modeling;

and 6, restraining and applying a load, comprising the following substeps:

step 6-1, entering a post-processing module, firstly selecting the rod unit end point represented by the array b to be restrained and fixed by using a'd' command through a cyclic program, and enabling the rod unit end point to be equivalent to a 'spring' structure, as shown in fig. 7;

step 6-2, applying equivalent load to the building nodes by adopting a cyclic command 'do', applying positive transverse load to the left half-side structure, applying negative transverse load to the right half-side structure, and applying symmetrical load of the symmetrical structure;

step 6-3, selecting the serial number of the point with the abscissa equal to the maximum value appearing in the abscissa in the step 5-11 in the process from the nodes represented by the array a by using a cyclic command, and exiting the cycle once the serial number is selected so as to obtain the serial numbers of the leftmost end node and the rightmost end node of the point, wherein the point is the tunnel contour;

6-4, performing negative vertical load application on the upper part of the structure by using a cyclic command according to the array number obtained in the step 6-3 to finish load constraint and application of the model, wherein the result is shown in FIG. 8;

and 7: and (3) result extraction and safety factor cloud picture display, comprising the following substeps:

7-1, solving the structure through finite element software ANSYS APDL to obtain the bending moment and the axial force of each unit, and extracting the bending moment and the axial force into an array;

7-2, selecting a target unit, namely a lining unit, extracting bending moment, axial force and shearing force of each unit by using an 'etable' command, and introducing the bending moment and the axial force into arrays of 'mm' and 'nn' which are designed in advance by using a 'get' command;

7-3, performing size eccentricity judgment and numerical operation on the units by using the cyclic command do and the selection command if to obtain the safety coefficients corresponding to the units;

in the formula: f_sThe safety factor of the tunnel lining units, the structural resistance when the R-structure reaches the load-bearing capacity limit, the S-effect, which is the force that the stressed part of the project theoretically can take must be greater than the force that it actually takes to prevent consequences due to the drawbacks of materials, deviations of operation, sudden increases of external forces, etc. when the project design of civil engineering, machinery, etc. is carried out;

and 7-4, recording the obtained safety coefficient result into a preset array, obtaining an array related to the bending moment in the step 7-2 of the process, replacing the array for recording the safety coefficient value with the array for recording the bending moment value, and displaying the safety coefficient of each unit according to the form of a bending moment diagram by using a plls command.

Based on the above contents, in the railway tunnel rapid safety evaluation method based on parametric modeling, the calibration and visual display of the safety coefficient of the rapid lining unit can be completed only by changing the radius and the angle of the multi-center circle determining the section size of the tunnel.

Preferably, the tunnel rapid safety evaluation method based on intensity reduction method and parametric modeling provided by the invention can also have the following characteristics: in step 2, the determined basic parameters include: the thickness of the lining unit, the diameter, arrangement mode, elastic modulus, Poisson ratio, weight and tensile strength standard values of steel bars in the reinforced concrete lining, the compression strength standard value, the elastic modulus and the protective layer thickness of concrete, and surrounding rock environment parameters.

Preferably, the tunnel rapid safety evaluation method based on intensity reduction method and parametric modeling provided by the invention can also have the following characteristics: in step 3, for the cross section of the four-center circular tunnel, four sections of circular arcs r₁r₂r₃r₄And angle alpha of the arc₁α₂α₃α₄，α₁+α₂+α₃+α₄＝180°；

The tunnel inverted arch bottom position is set as a coordinate system origin position, and the coordinates of each circle center are determined as follows:

O₁：(0，(r₂-r₃)cos(α₃+α₄)+r₄-(r₄-r₃)cosα₄+(r₂-r₁)cosα₁)，

O₂：((r₂-r₁)sinα₁，(r₂-r₃)cos(α₃+α₄)+r₄-(r₄-r₃)cosα₄)，

O₃：((r₃-r₄)sinα₄，r₄-(r₄-r₃)cosα₄)，

O₄：(0，r₄)。

the other n-center circles are the same.

Preferably, the tunnel rapid safety evaluation method based on intensity reduction method and parametric modeling provided by the invention can also have the following characteristics: in the step 7-3, in the unit safety coefficient equation for calculating the concrete lining, the action effect is shown as the formula (1), and the structural resistance is shown as the formula (2) and the formula (3):

S＝N (1)

a) when eccentricity e₀When the time is more than 0.2h, the bearing capacity of the cross section of the lining structure is determined by the tensile limit state, and then the safety coefficient calculation equation is as follows:

b) when eccentricity e₀When the bearing capacity of the cross section of the lining structure is in a tensile limit state less than 0.2h, the safety coefficient in the calculation equation is as follows: .

R＝αf_cbh (3)

Wherein, S-effect; r-bearing capacity; m-bending moment; n-axial force; b-section width, b ═ 1; h-section height; f. of_t-core tensile strength of the lining concrete; gamma ray_p-the coefficient of resistance of the concrete section to the effects of the moment and plasticity is constant; f. of_c-axial compressive strength (MPa) of the lining concrete; the alpha-axial force eccentricity influence coefficient;

the structural resistance in the calculation of the safety coefficient of the reinforced concrete lining is shown as the formula (4), and the action effect is shown as the formula (5):

in the formula, alpha₁-a concrete strength factor, alpha, when the concrete strength rating is not greater than C50₁Taking 1.0, when the concrete strength grade is C80, alpha₁Take alpha at 0.94, other intensity levels₁Values, interpolation may be used; x-concrete compression zone height; h is₀-cutting offEffective height of the surface, h₀＝h-a_s；σ′_s-reinforcement compressive strength; a'_s-longitudinal rebar cross-sectional area of the compression zone; a'_s-the distance from the centroid of the longitudinal bars of the compression zone to the compression edge of the section; a is_s-distance of longitudinal rebar centroid to cross-sectional tensile edge of tensile zone; e.g. of the type_aAdditional eccentricity, taking the greater of both 20mm and 1/30, the maximum dimension of the cross section in the direction of eccentricity.

< apparatus >

Further, the invention also provides a tunnel rapid safety evaluation device based on parametric modeling, which is characterized by comprising the following steps:

the discrete part is used for discretizing a tunnel structure system consisting of a lining and surrounding rocks into a limited number of lining units and spring units;

a basic parameter determining part, which determines a basic parameter value as a model input parameter according to the actual measurement data of the tunnel to be evaluated;

the tunnel section variable and position determining part is used for determining key parameter variables of the n-center circle tunnel section for parametric modeling, wherein the n is larger than or equal to 1 and comprises the arc radius and the angle, and determining the position of the tunnel section;

a unit determining part for determining a beam unit of a reaction tunnel section composite lining structure and a rod unit for simulating the action of surrounding rocks, and defining a specific real constant according to the size of the actual size;

a tunnel section drawing section for drawing a tunnel section according to the following steps 5-1 to 5-15;

step 5-1, enabling an operator to input the circle center positions of the circular arcs in sequence, generating the circle center coordinates of the circular arcs into class 1 key points, and generating key points at the vault positions in the same way;

step 5-2, sequentially making arcs corresponding to the n-center tunnel section by taking the class 1 key points generated in the previous step as the circle center, taking r as the radius and taking alpha as the circle center, recording the point with the largest number as a class 2 key point by using a get command after the generation of the arc in each step according to the characteristic that the serial numbers of the key points of the ANSYS work interface are accumulated continuously, and drawing the arc by taking the class 2 key point as an initial point in the process of drawing the arc in each step;

step 5-3, making the circle center of the type 1 key point, wherein r is the radius, and alpha/2 is the arc corresponding to the angle in sequence, repeating the operation of step 5-2, generating the key point after each arc is finished, using the key point as the type 3 key point, dividing each arc line into two sections, and recording the midpoint position of the arcs, thereby obtaining the starting point, the midpoint and the ending point of each arc on the half side of the n-center circular section;

5-4, deleting lines by using an 'ldele' command, then using a 'larc' command to take the key points of the type 2 and the key points of the vault positions as two end points of the circular arc, taking the key points of the type 3 as important points through which the circular arc passes to make the circular arc, and connecting the connected circular arcs in sequence by using an 'lcomb' command to serve as a circular arc line 1;

step 5-6, "lsel" selects all lines, "size" command divides the arc line into the desired number of units, "lmesh" command performs unit division, and then "nummrg" command performs node integration;

step 5-8, defining each node by adopting an array, defining an array a as a tunnel lining unit node storage array, and defining a (1) as an inverted arch bottom initial point unit number;

step 5-10, selecting the node on the right side of the tunnel section, taking the node at the vault position as an initial point, and recording the nodes in the array a in sequence by circularly utilizing a 'near' command to order the nodes like the step 5-9;

step 5-12, selecting a beam unit to successively connect each node represented by the array through an e command by using a cyclic program, and performing parameter assignment at the same time;

step 5-14, setting a node of an outer ring rod unit end point for simulating the surrounding rock action, setting the outer ring radius l as r +1, repeating the operation steps 5-2 to 5-10, setting the node of the rod unit end point part as an array b, wherein the array b is consistent with the array a in sequence and is positioned on the outer ring of the lining unit;

step 5-15, selecting a rod unit, correspondingly connecting each node represented by the array a and the array b sequentially through an 'e' command by using a cyclic program, and simultaneously carrying out parameter assignment to complete parametric modeling;

a restraining and load applying part for applying a load on the tunnel cross-section structure according to the following steps 6-1 to 6-4;

step 6-1, entering a post-processing module, firstly, selecting the rod unit end point represented by the array b to be restrained and fixed by using a'd' command through a cyclic program, and enabling the rod unit end point to be equivalent to a 'spring' structure;

6-4, performing negative vertical load application on the upper part of the structure by using a cyclic command according to the array number obtained in the step 6-3 to finish load constraint and application of the model;

a result extraction unit for obtaining safety factors corresponding to the units according to the following steps 7-1 to 7-3;

7-1, solving the structure through finite element software ANSYSAPDL to obtain the bending moment and the axial force of each unit, and extracting the bending moment and the axial force into an array;

7-2, selecting lining units, extracting bending moment, axial force and shearing force of each unit by using an 'etable' command, and introducing the bending moment and the axial force into arrays of 'mm' and 'nn' which are designed in advance by using a 'get' command to obtain arrays of bending moment;

7-3, utilizing a cyclic command do and a selection command if to judge the size eccentricity of the unit and calculate the numerical value;

the safety coefficient cloud chart generating part records the obtained safety coefficient result into a preset array, replaces the array for recording the magnitude of the safety coefficient value with the array for recording the magnitude of the bending moment, and displays the safety coefficient of each unit in a bending moment chart form by using a 'plls' command to obtain a safety coefficient cloud chart;

the input display part is used for enabling a user to input an operation instruction and carrying out corresponding display;

and the control part is in communication connection with the dispersion part, the basic parameter determination part, the tunnel section variable and position determination part, the unit determination part, the tunnel section drawing part, the constraint and load application part, the result extraction part, the safety coefficient cloud picture generation part and the input display part and controls the operation of the dispersion part, the basic parameter determination part, the tunnel section variable and position determination part, the unit determination part, the tunnel section drawing part, the constraint and load application part, the result extraction part, the safety coefficient cloud picture generation part and the input display part.

Preferably, the device for evaluating the rapid safety of the tunnel based on the parametric modeling provided by the present invention may further include: in the basic parameter determination part, an operator inputs the thickness of the lining unit, the diameter, arrangement mode, elastic modulus, Poisson ratio, weight and tensile strength standard values of the steel bars in the reinforced concrete lining, the compression strength standard value, elastic modulus and protective layer thickness of the concrete, and surrounding rock environment parameters as model input parameters according to the measured data of the tunnel to be evaluated.

Preferably, the device for evaluating the tunnel rapid safety based on the parametric modeling provided by the invention can further have the following characteristics: and the input display part displays the safety coefficient cloud picture generated by the safety coefficient cloud picture generation part, and displays the specific safety coefficient at the corresponding position of the tunnel section structure in different colors according to the numerical range.

Action and Effect of the invention

According to the tunnel rapid safety evaluation method and device based on parametric modeling, the traditional node positions are replaced by the arrays, one-key parametric modeling is realized, modeling, finite element calculation and safety coefficient calculation are matched with each other in a coordinated mode, a large amount of time can be shortened in tunnel section design, internal force data do not need to be led into calculation software, the error probability is reduced, the design efficiency is greatly improved, safety coefficients are displayed through a safety coefficient cloud picture, an operator can rapidly, intuitively and comprehensively obtain tunnel safety coefficient information, and convenience, rapidness, intuition, refinement, accuracy and high efficiency are really achieved.

Drawings

FIG. 1 is a flow chart of a rapid safety evaluation method for a railway tunnel based on parametric modeling according to the present invention;

FIG. 2 is a cross-sectional view of a multi-centered circular tunnel according to the present invention;

FIG. 3 is a cross-sectional half profile of a tunnel according to the present invention;

FIG. 4 is a diagram illustrating node numbers represented by arrays according to the present invention;

FIG. 5 is a profile view of a tunnel model according to the present invention;

FIG. 6 is a drawing of a cross-sectional model of a tunnel according to the present invention;

FIG. 7 is a diagram of the effects of constraints on a model according to the present invention;

FIG. 8 is a load applying diagram of a structure according to the present invention;

FIG. 9 is a modular view of a lining structural unit according to the present invention;

FIG. 10 is a graph of constraints and applied loads to which the present invention relates;

FIG. 11 is a graph showing the safety factor involved in the present invention;

FIG. 12 is a cross-sectional style drawing generated by CAD using a prior art method in a comparative example;

FIG. 13 is a node numbering diagram after partitioning by a prior art method in a comparative example;

FIG. 14 is a schematic view of a lining structural unit obtained by the method of the present invention in a comparative example;

FIG. 15 is a graph showing the safety factor obtained by the method of the present invention in the comparative example;

FIG. 16 is a cloud of safety coefficient results for linings of different thicknesses obtained by the method of the invention in a comparative example: FIG. 16(a) Lining 0.45 m; FIG. 16(b) Lining 0.46 m; FIG. 16(c) Lining 0.47 m; FIG. 16(d) Lining 0.48 m; FIG. 16(e) Lining 0.49 m; FIG. 16(f) Lining 0.50 m; FIG. 16(g) Lining 0.51 m; FIG. 16(h) Lining 0.52 m; FIG. 16(i) Lining 0.53 m; FIG. 16(j) Lining 0.54 m; FIG. 16(k) Lining 0.55 m; FIG. 16(l) Lining 0.56 m.

Detailed Description

The following describes in detail specific embodiments of the tunnel rapid security evaluation method and apparatus based on parametric modeling according to the present invention with reference to the accompanying drawings.

< example one >

In this embodiment, by using the tunnel rapid safety evaluation method based on parametric modeling of the present invention, taking a standard tunnel section of a two-track railway with a speed per hour of 200km as an example, the safety coefficients of the units under the condition of deep burying in a v-level surrounding rock environment are calculated.

1. Determining basic parameters and assigning values

The tunnel is structurally designed by adopting values recommended in the current specification, the secondary lining is made of C35 strength concrete, the inner side and the outer side of the tunnel are made of HRB335 strength steel bars, the design parameters are shown in table 1, the parameters of the V-level surrounding rock are shown in table 2, the load bearing ratio is 0.7, the parameters of the HRB335 strength steel bars are shown in table 3, the parameters of the C35 strength concrete are shown in table 4, and the number of lining units is determined to be 90 in order to ensure the calculation accuracy.

TABLE 1 Reinforcement parameters of double-track tunnel standard diagram for passenger-cargo collinear railways at 200 km/h

TABLE 2 surrounding rock parameters of class V

TABLE 3 HRB335 Steel Bar parameters

TABLE 4C 35 concrete parameters

2. Inputting key parameters to carry out parametric modeling

According to a section diagram recommended in railway tunnel specifications, determining that the radius of each circular arc of a multi-center circle of a double-track railway tunnel at the speed of 200km per hour is r₁＝6.03、r₂＝6.03、r₃＝2.5、r₄The angles corresponding to the arcs are respectively 72 °, 35 ° and 50 °, and a lining structure load-structural method calculation model is constructed as shown in fig. 9, and the array a is determined as an array representing the node of the lining unit, the array b is determined as an array representing the node of the rod unit, and the arrays are sequentially connected by using a cyclic command.

3. Setting a restraining applied load

For the model completed in the previous step, the cyclic command is used to apply the horizontal and longitudinal constraints on the rod unit node represented by the array b, and the cyclic command is used to apply the horizontal and vertical loads on the lining unit node represented by the array a, and the result is shown in fig. 10.

4. Solve and extract the results

And (4) solving the structure by using finite element software ANSYSAPDL, obtaining the bending moment and the axial force of each unit, and extracting the bending moment and the axial force into an array.

5. Judging lining type

The structure is a reinforced concrete structure, so the calculation is carried out by adopting the formula (3) and the formula (4), and the size eccentricity judgment and the calculation of the safety coefficient of the reinforced concrete lining unit are completed in the program.

In the case of concrete lining (without reinforcement), the calculation is carried out according to equations (1) to (3).

6. Visual result display

The calculated result is imported into an array of statistical bending moment data, the safety factors of all units are displayed by utilizing a plls command as shown in fig. 11, the result data are displayed, and weak positions and distribution in the structure can be displayed; the control section of the obtained reinforced concrete lining unit is arranged at the vault part, the minimum safety factor is 2.15734, the maximum safety factor is 12.5839, and the safety factor value of each unit can be directly given by an array.

Because the requirements on the safety coefficient are different under different environments, the basic parameters of the tunnel, such as concrete strength, steel bar diameter and the like, can be continuously adjusted through the process, so that the engineering requirements are met.

The embodiment is based on four-center circle modeling, for any n-center circle, the arc parts can be disassembled into the arc parts with the same radius and the same circle center, the central angles are added to meet the multi-section arc form of the arc, the multi-section arc form is then brought into a program to finish the calibration of the safety coefficient of the tunnel lining unit, and the selection, judgment and calculation appearing in the graph can be finished by using ANSYSAPDL.

< example two >

The second embodiment provides a device for rapidly determining section safety factor conditions by using a tunnel rapid safety evaluation method based on parametric modeling, and the device comprises a dispersion part, a basic parameter determination part, a tunnel section variable and position determination part, a unit determination part, a tunnel section drawing part, a constraint and load application part, a result extraction part, a safety factor cloud picture generation part, an input display part and a control part.

The discrete part is used for discretizing a tunnel structure system consisting of the lining and the surrounding rock into a limited number of lining units and spring units.

The basic parameter determining part determines a basic parameter value as a model input parameter according to actual measurement data of the tunnel to be evaluated; in the basic parameter determining part, an operator inputs the thickness of the lining unit, the diameter, arrangement mode, elastic modulus, Poisson's ratio, weight and tensile strength standard values of the steel bars in the reinforced concrete lining, the compression strength standard value, elastic modulus and protective layer thickness of the concrete, and surrounding rock environment parameters as model input parameters according to the measured data of the tunnel to be evaluated.

The tunnel section variable and position determining part determines key parameter variables of the n-center circle tunnel section for parametric modeling, wherein the n-center circle tunnel section comprises the arc radius and the angle, n is larger than or equal to 1, and the position of the tunnel section is determined.

And a unit determination part which determines a beam unit of a reaction tunnel section composite lining structure and a rod unit for simulating the action of surrounding rocks, and defines a specific real constant according to the size of the actual size.

The tunnel section drawing section draws a tunnel section according to the following steps 5-1 to 5-15:

step 5-1, sequentially inputting the circle center positions of the arcs, generating the circle center coordinates of the arcs into class 1 key points, and generating key points at the dome top positions;

and 5-15, selecting a rod unit, correspondingly connecting each node represented by the array a and the array b sequentially through an e command by using a cyclic program, and simultaneously carrying out parameter assignment to complete parametric modeling.

The restraining and load applying part applies a load on the tunnel section structure according to the following steps 6-1 to 6-4:

and 6-4, performing negative vertical load application on the upper part of the structure by using a cyclic command according to the array number obtained in the step 6-3 to finish load constraint and application of the model.

The result extraction unit obtains the safety factor corresponding to each cell in accordance with the following steps 7-1 to 7-3:

and 7-3, performing size eccentricity judgment and numerical operation on the unit by using the cyclic command do and the selection command if.

And the safety coefficient cloud picture generation part records the obtained safety coefficient result into a preset array, replaces the array for recording the magnitude of the safety coefficient value with the array for recording the magnitude of the bending moment, and displays the safety coefficient of each unit according to the form of the bending moment picture by using a 'plls' command to obtain the safety coefficient cloud picture.

The input display part is used for allowing a user to input an operation instruction and performing corresponding display; specifically, the input display part can display the parameters to be input in the basic parameter determination part, so that an operator can input actual measurement parameter values; the input display part can also display the circle center number, the coordinates, the arc radius and the angle of the tunnel section determined by the tunnel section variable and position determination part according to the instruction; the input display part can also display the tunnel section diagram drawn by the tunnel section drawing part according to the instruction, display the load constraint of the model and the applied tunnel section diagram according to the instruction display constraint and the load applying part, display the safety factor of each unit acquired by the instruction display result extraction part, display the safety factor cloud diagram generated by the safety factor cloud diagram generation part, and display the specific safety factor at the corresponding position of the tunnel section structure in different colors according to the numerical range.

The control part is in communication connection with the discrete part, the basic parameter determining part, the tunnel section variable and position determining part, the unit determining part, the tunnel section drawing part, the constraint and load applying part, the result extracting part, the safety coefficient cloud picture generating part and the input display part, and controls the operation of the discrete part, the basic parameter determining part, the tunnel section variable and position determining part, the unit determining part, the tunnel section drawing part, the constraint and load applying part, the result extracting part, the safety coefficient cloud picture generating part and the input display part.

< comparative example >

The safety factor is obtained by adopting the prior art:

and (3) selecting the parameters given in the step 1 in the first embodiment, and performing safety coefficient operation by using a traditional method.

1. Drawing a cross-sectional view

And (4) constructing a standard section diagram of the tunnel in the CAD, outputting the standard section diagram as a surface area, and generating an SAT file.

2. Determining node location

Importing a sat file into ANSYSAPDL, deleting redundant lines in the middle, connecting circular arcs, displaying a complete tunnel modeling lining node and a contour map of a rod unit node simulating the surrounding rock action by using a symmetrical command, randomly setting unit types and numbering, dividing the four circular arcs by using a 'lesize' command to generate the required number of nodes, clicking List > nodes > coordinatestonoly, and obtaining the number and the coordinates of each node.

3. Node arrangement

In order to save time by using a cyclic command in the load application process, the corresponding node numbers and coordinates are imported into the excel, and the nodes are sequentially adjusted in the excel with reference to the positions of the node numbers in fig. 13.

4. Modeling

According to a normal modeling sequence, node numbers and coordinates of nodes are input step by step through an 'n' command, then lining nodes and rod unit nodes are connected step by step through an 'e' command, and units are generated and assigned.

5. Solving for

And (3) restraining the displacement of the node of the rod unit, applying a load, and obtaining the internal force of the structure through the solving function of finite element software.

6. Factor of safety calculation

Due to the symmetry of the model, only half of the model units need to be calculated, and the internal forces of all the units of the structure are extracted, as shown in table 5.

TABLE 5 internal force of each unit

The bending moment and the axial force are introduced into the equation for solving the safety coefficient in the above formula, and the safety coefficient of each unit is obtained, as shown in table 6.

TABLE 6 safety factor of each unit

The control section of the obtained reinforced concrete lining unit is located at the vault part, the minimum safety factor is 2.2648, the maximum safety factor is 12.6008, the difference in safety factors is not large and the accuracy is equivalent in the first comparative embodiment of the invention, and the first embodiment and the prior art method are used for calculating the simplest standard section. The method can be used for modeling by one-key parameterization, integrates modeling, finite element calculation and safety coefficient calculation, and can also be used for generating a safety coefficient cloud chart to visually display the safety coefficients at different positions of the section of the tunnel, so that the processing time is greatly saved, error data caused by complicated processing is effectively avoided, and the accuracy of the result is ensured.

For tunnel design under different geological conditions or engineering requirements, the safety coefficient of a lining unit of the tunnel design needs to meet different values, and if the lining thickness needs to be changed, the self weight of the structure can affect internal force, so that modeling calculation needs to be carried out again by adopting the method in the prior art, the internal force is derived and is brought into calculation software for calculation, the optimal design effect is achieved after calculation for many times, complexity and redundancy are realized, the efficiency is low, and mistakes are easy to make.

The method can directly change the parameter value to be changed in the command, change the lining thickness, the diameter of the steel bar, the reinforcement ratio and other values in the basic variable input stage, and quickly and accurately obtain the result.

The method can also be adopted to design the sections of railway tunnels with different speed per hour, for example, the radius of each circular arc of a multi-center circle of a railway with 160km speed per hour is r respectively under the same design environment₁＝5.40、r₂＝7.72、r₃＝1.70、r₄13.5, the angles corresponding to the arcs are respectively 60 degrees, 40 degrees and 59 degrees, a lining structure load-structure method calculation model is constructed as shown in figure 14,the safety factor results are illustrated in the cloud graph of fig. 15.

For the section design process in the reinforcement checking calculation, the structure dead weight is changed in the finite element calculation process due to the change of the thickness of the lining section, and modeling and real constant assignment are required to be carried out again in the modeling process of the prior art. For example, the safety factor of a certain section of tunnel section lining unit is set to be 2.20, the initial lining thickness of the lining unit is set to be 0.45m by adopting the environmental parameters given in the example, and the diameter of the steel bar is kept unchanged.

When designing according to the prior art method, it is necessary to build a model according to the method in the example, and then derive the internal force to perform the safety factor calculation:

(1) and when the lining thickness is 0.45m, repeating the steps, reestablishing a finite element model, deriving the internal force, obtaining the minimum safety factor of the lining unit in the calculation software, wherein the minimum safety factor is 2.092, the minimum safety factor does not meet the design requirement, the section thickness needs to be increased, and the thickness is adjusted to be 0.46 m.

(2) And when the lining thickness is 0.46m, repeating the steps, reestablishing a finite element model, deriving the internal force, obtaining the minimum value of the safety coefficient of the lining unit in the calculation software to be 2.100, not meeting the design requirement, needing to increase the section thickness and adjusting the thickness to be 0.47 m.

(3) And when the lining thickness is 0.47m, repeating the steps, reestablishing a finite element model, deriving the internal force, obtaining the minimum value of the safety coefficient of the lining unit in the calculation software to be 2.117, not meeting the design requirement, needing to increase the section thickness and adjusting the thickness to be 0.48 m.

(4) And when the lining thickness is 0.48m, repeating the steps, reestablishing a finite element model, deriving the internal force, obtaining the minimum safety factor of the lining unit in the calculation software, wherein the minimum safety factor is 2.132, the minimum safety factor does not meet the design requirement, the section thickness needs to be increased, and the thickness is adjusted to be 0.49 m.

(5) And when the lining thickness is 0.49m, repeating the steps, reestablishing a finite element model, deriving the internal force, obtaining the minimum value of the safety coefficient of the lining unit in the calculation software to be 2.145, not meeting the design requirement, needing to increase the section thickness, and adjusting the thickness to be 0.50 m.

(6) And when the lining thickness is 0.50m, repeating the steps, reestablishing a finite element model, deriving the internal force, obtaining the minimum value of the safety coefficient of the lining unit in the calculation software to be 2.157, not meeting the design requirement, needing to increase the section thickness, and adjusting the thickness to be 0.51 m.

(7) And when the lining thickness is 0.51m, repeating the steps, reestablishing a finite element model, deriving the internal force, obtaining the minimum value of the safety coefficient of the lining unit in the calculation software, wherein the minimum value is 2.168, the design requirement is not met, the section thickness needs to be increased, and the thickness is adjusted to be 0.52 m.

(8) And when the lining thickness is 0.52m, repeating the steps, reestablishing a finite element model, deriving the internal force, obtaining the minimum safety factor of the lining unit in the calculation software, wherein the minimum safety factor is 2.177, the minimum safety factor does not meet the design requirement, the section thickness needs to be increased, and the thickness is adjusted to be 0.53 m.

(9) And when the lining thickness is 0.53m, repeating the steps, reestablishing a finite element model, deriving the internal force, obtaining the minimum safety coefficient value of the lining unit in the calculation software, wherein the minimum safety coefficient value is 2.184, the minimum safety coefficient value does not meet the design requirement, the section thickness needs to be increased, and the thickness is adjusted to be 0.54 m.

(10) And when the lining thickness is 0.54m, repeating the steps, reestablishing a finite element model, deriving the internal force, obtaining the minimum safety coefficient value of the lining unit in the calculation software, wherein the minimum safety coefficient value is 2.190, the minimum safety coefficient value does not meet the design requirement, the section thickness needs to be increased, and the thickness is adjusted to be 0.55 m.

(11) And when the lining thickness is 0.55m, repeating the steps, reestablishing a finite element model, deriving the internal force, obtaining the minimum value of the safety coefficient of the lining unit in the calculation software to be 2.194, not meeting the design requirement, needing to increase the section thickness, and adjusting the thickness to be 0.55 m.

(12) When the thickness of the lining is 0.56m, repeating the steps, reestablishing a finite element model, deriving the internal force, and obtaining the minimum value of the safety coefficient of the lining unit in the calculation software to be 2.206, so that the design requirement is met. The safety factor requirement of the engineering can be met when the lining thickness is 0.56 m.

For the method, the model can be changed only by adjusting the parameters of the lining thickness, the safety coefficient calculation is directly carried out again, the calculation steps are greatly simplified, and when the lining thickness is locked, the safety coefficient cloud chart is directly output by one key to obtain the minimum safety coefficient value of the lining unit, as shown in fig. 16.

In the process, the thickness of the lining is changed, and the diameter of the steel bar can be continuously adjusted if the diameter of the steel bar needs to be changed. The safety factor obtained by the prior art method for the 12 sections takes more than 2 hours, and the 12 safety factor clouds shown in fig. 16 can be generated in less than 20 minutes by the method of the invention.

In conclusion, the method has the advantages that the traditional node positions are replaced by the arrays, the one-key parametric modeling can be realized only by a few parameters, the modeling, the finite element calculation and the safety coefficient calculation are integrated, the safety coefficient visual display program is compiled, and the convenience, the rapidness, the visual refining, the accuracy and the high efficiency are really realized. Meanwhile, in the design process of the sections with different shapes, the modeling can be quickly carried out through specific parameters, the problem that the modeling of the traditional scheme is complex and the time consumption is too long is solved, in the design process of the sections, the influence on structural stress caused by the change of the thickness of the lining in the traditional scheme needs to continuously repeat the modeling process, the design of the sections can be completed only by changing the parameters for controlling the thickness of the lining in the scheme, and the reinforcement can also be completed by changing the parameters for controlling various variables, so that the calculation of target results is realized in a program. Compared with the prior art, the method has the advantages of greatly improving time, operability and error rate avoidance.

The above embodiments are merely illustrative of the technical solutions of the present invention. The method and apparatus for evaluating tunnel safety based on parameterized modeling in the present invention are not limited to the content described in the above embodiments, but only to the scope defined by the claims. Any modification or supplement or equivalent replacement made by a person skilled in the art on the basis of this embodiment is within the scope of the invention as claimed in the claims.

Claims

1. A tunnel rapid safety evaluation method based on parametric modeling is characterized by comprising the following steps:

step 1, discretization:

step 2, determining basic parameters:

step 3, determining that the n-center circular tunnel section for parametric modeling contains key parameter variables of arc radius and angle, wherein n is more than or equal to 1, and determining the position of the tunnel section;

step 4, determining unit type, material parameters and real constants:

determining a beam unit of a composite lining structure of a reaction tunnel section and a rod unit for simulating the action of surrounding rocks, and defining a real constant according to the size of the actual size;

step 5, drawing the section of the tunnel, comprising the following substeps:

and 6, restraining and applying a load, comprising the following substeps:

step 6-1, entering a post-processing module, selecting the rod unit end point represented by the array b to restrain and fix by using a'd' command and a cyclic program, and enabling the rod unit end point to be equivalent to a 'spring' structure;

7-2, selecting lining units, extracting bending moment, axial force and shearing force of each unit by using an 'etable' command, and introducing the bending moment and the axial force into arrays of 'mm' and 'nn' which are designed in advance by using a 'get' command;

2. The method for rapidly evaluating the safety of the tunnel based on the parametric modeling according to claim 1, wherein:

in step 2, the determined basic parameters include: the thickness of the lining unit, the diameter, arrangement mode, elastic modulus, Poisson ratio, weight and tensile strength standard values of steel bars in the reinforced concrete lining, the compression strength standard value, the elastic modulus and the protective layer thickness of concrete, and surrounding rock environment parameters.

3. The method for rapidly evaluating the safety of the tunnel based on the parametric modeling according to claim 1, wherein:

wherein, in step 3, for the cross section of the four-center circular tunnel, four sections of circular arcs r₁ r₂ r₃ r₄And angle alpha of the arc₁ α₂ α₃α₄，α₁+α₂+α₃+α₄＝180°；

O₁:(0,(r₂-r₃)cos(α₃+α₄)+r₄-(r₄-r₃)cosα₄+(r₂-r₁)cosα₁)，

O₂:((r₂-r₁)sinα₁,(r₂-r₃)cos(α₃+α₄)+r₄-(r₄-r₃)cosα₄)，

O₃:((r₃-r₄)sinα₄,r₄-(r₄-r₃)cosα₄)，

O₄:(0,r₄)。

4. the method for rapidly evaluating the safety of the tunnel based on the parametric modeling according to claim 1, wherein:

in the step 7-3, in the calculation unit safety coefficient equation for the concrete lining, the action effect is shown as the formula (1), and the structural resistance is shown as the formula (2) and the formula (3):

S＝N (1)

a) when eccentricity e₀>When 0.2h is needed, the bearing capacity of the cross section of the lining structure is determined by the tensile limit state, and then the safety coefficient calculation equation is as follows:

b) when eccentricity e₀<When 0.2h, the bearing capacity of the cross section of the lining structure is in a tensile limit state, and then in a safety coefficient calculation equation: .

R＝αf_cbh (3)

Wherein, S-effect; r-bearing capacity; m-bending moment; n-axial force; b-section width, b ═ 1; h is the height of the section; f. of_t-lining concrete axial tensile strength; gamma ray_p-the coefficient of resistance of the concrete section to the effects of the moment and plasticity is a constant; f. of_c-lining concrete axial compressive strength; alpha-axial force eccentricity influence coefficient;

in the formula, alpha₁-concrete strength factor; x is the height of the concrete compression zone; h is₀-effective height of the section; sigma'_s-the compressive strength of the reinforcing bar; a'_s-longitudinal bar cross-sectional area of the compression zone; a'_s-the distance from the centroid of the longitudinal reinforcement of the compression zone to the compression edge of the section; a is_s-distance from centroid of longitudinal reinforcement of tension zone to tension edge of section; e.g. of the type_a-additional eccentricity.

5. A tunnel rapid safety evaluation device based on parametric modeling is characterized by comprising:

the safety coefficient cloud picture generation part records the obtained safety coefficient result into a preset array, replaces the array for recording the magnitude of the safety coefficient value with the array for recording the magnitude of the bending moment, and displays the safety coefficient of each unit in a bending moment picture form by using a 'plls' command to obtain a safety coefficient cloud picture;

and the control part is in communication connection with the dispersion part, the basic parameter determination part, the tunnel section variable and position determination part, the unit determination part, the tunnel section drawing part, the constraint and load application part, the result extraction part, the safety factor cloud picture generation part and the input display part to control the operation of the dispersion part, the basic parameter determination part, the tunnel section variable and position determination part and the unit determination part.

6. The device for rapidly evaluating the safety of the tunnel based on the parametric modeling according to claim 5, wherein:

in the basic parameter determining part, an operator inputs the thickness of the lining unit, the diameter, arrangement mode, elastic modulus, Poisson's ratio, weight and tensile strength standard values of the steel bars in the reinforced concrete lining, the compression strength standard value, elastic modulus and protective layer thickness of the concrete, and surrounding rock environment parameters as model input parameters according to the measured data of the tunnel to be evaluated.

7. The device for rapidly evaluating the safety of the tunnel based on the parametric modeling according to claim 5, wherein:

the input display part displays the safety coefficient cloud picture generated by the safety coefficient cloud picture generation part, and specific safety coefficients are displayed at corresponding positions of the tunnel section structure in different colors according to the numerical range.