Mountain tunnel earthquake damage risk grade assessment method

Abstract

The invention discloses a mountain tunnel earthquake damage risk grade assessment method, which specifically comprises the following steps: investigating and surveying earthquake events at home and abroad, carrying out statistical analysis on tunnels with earthquake damage, and establishing a tunnel earthquake risk assessment index system; introducing a subjective and objective comprehensive weighting method, calculating an entropy value of each index according to the variation degree of the selected index, and performing normalization processing; determining a risk evaluation level; different earthquake risk evaluation grades are determined by combining tunnel aseismic design related specifications and engineering practice; calculating the comprehensive weight of the evaluation index by adopting a distance function; determining a correlation function; obtaining a comprehensive correlation degree under the risk level through the correlation degree and a corresponding weight coefficient; and determining a tunnel earthquake damage risk level. According to the method, the earthquake damage risk of the tunnel can be evaluated in the preliminary design stage of the tunnel, targeted design can be performed in the design stage according to the risk level, the risk of tunnel collapse is reduced, and harm caused by earthquakes is reduced.

Description

Technical Field

[0001] The invention belongs to the field of tunnel risk assessment and management, and in particular relates to a method for assessing the earthquake damage risk level of a mountain tunnel. Background Art

[0002] Earthquake damage surveys show that tunnel structures have suffered varying degrees of damage, with common damages including tunnel deformation and cracking, lining seepage and leakage, concrete block falling, tunnel portal collapse and tunnel collapse. Post-earthquake repair of tunnels is a difficult task, especially for tunnels located on important routes. If earthquake damage occurs, the losses will be immeasurable. With the increase in the use of underground space, the number of tunnels located in high-intensity earthquake zones is also increasing. How to quantify the earthquake risk of tunnels is a complex research task. Reasonable earthquake risk assessment of tunnels is conducive to understanding the safety of tunnels, and targeted reinforcement of tunnel structures with higher earthquake risks can be carried out to reduce the loss of life and property caused by tunnel damage during earthquakes. Summary of the invention

[0003] In view of the above problems, the present invention provides a method for assessing the earthquake damage risk level of a mountain tunnel.

[0004] A method for assessing the earthquake damage risk level of a mountain tunnel of the present invention comprises the following steps:

[0005] Step 1: Investigate earthquake events at home and abroad, conduct statistical analysis on tunnels that have suffered earthquake damage, and establish a tunnel earthquake risk assessment indicator system.

[0006] Step 2: Introduce the subjective and objective comprehensive weighting method, calculate the entropy value of each indicator according to the variation degree of the selected indicator, and perform normalization processing:

[0007]

[0008]

[0009] Among them, P ij represents the weight of the jth tunnel under the i-th evaluation index, r ij represents the value of the i-th evaluation index of the j-th tunnel, and x and y represent the number of evaluation indexes and the number of tunnels.

[0010] The entropy weight, i.e., the objective weight, of each evaluation index is calculated according to the following formula:

[0011]

[0012] Invite n experts in the industry to score, construct a judgment matrix and use hierarchical analysis method, use the geometric mean method to obtain the weight vector, and multiply each row of the judgment matrix:

[0013]

[0014] In the formula, x t Represents the elements of each row of the judgment matrix.

[0015] right Normalize and get the subjective weight W of each indicator i ;

[0016]

[0017] Step 3: Determine the risk assessment level; determine different earthquake risk assessment levels based on relevant tunnel seismic design specifications and engineering practices.

[0018] Step 4: Use the distance function to calculate the comprehensive weight of the evaluation index according to the following formula:

[0019]

[0020]

[0021] Where α and β represent the weights obtained by the analytic hierarchy process and the adjustment coefficients multiplied by the weights obtained by the improved entropy weight method.

[0022] The comprehensive weight of the evaluation index is a linear combination of the results obtained by calculating the subjective weight and the objective weight:

[0023]

[0024] Step 5: Determine the correlation function; the correlation function expresses the degree of membership of each indicator of the object to be evaluated with respect to each evaluation level. The correlation degree of the indicator is calculated according to the definition of distance in extenics. The calculation formula is:

[0025]

[0026] In the formula, ρ(u i ,U ij ) represents u i with U ij =[a ij ,b ij ], the calculation method is according to formula (10):

[0027]

[0028] D(u i ,U ij ,U ip ) represents point u i About interval U ij and interval U ip The place value of The calculation method is according to formula (11). The position value and distance can quantitatively express the position relationship between the point and the interval;

[0029]

[0030] In the formula, u i is the value of the object element to be evaluated after normalization, U ij is the normalized classical domain, U ip is the normalized section domain; α ij is the lower bound of the classical domain, b ij is the upper bound of the classical domain.

[0031] Step 6: Determine the tunnel earthquake damage risk level; obtain the comprehensive correlation degree K under risk level J through the correlation degree and the corresponding weight coefficient j (p):

[0032]

[0033] Where: i Represents the weight coefficient of the i-th evaluation index; K j (u i ) represents the correlation degree of the i-th evaluation index at level J.

[0034] K of the matter-element p to be evaluated j The larger the (p) value, the smaller the deviation of the indicator from the evaluation level. j0 (p) = max[K j (p)(j=1,2,…,m)], then the seismic risk of the tunnel to be evaluated is level j0;

[0035]

[0036] j * is the grade variable of the tunnel to be evaluated, reflecting the degree to which P is biased towards the adjacent grade.

[0037] Furthermore, earthquake risk assessment indicators are divided into three categories: geological conditions of the tunnel site, tunnel status, structural conditions and earthquakes; among them, the geological conditions of the tunnel site include surrounding rock grade, surrounding rock weathering conditions and tunnel entrance slope angle; the tunnel status includes the maximum burial depth of the tunnel, tunnel disease conditions and cross-sectional size and form; the structural conditions and earthquakes include the length of the fault's fracture zone, the earthquake intensity of the tunnel site and the adverse geology of the tunnel site.

[0038] Furthermore, earthquake risk assessment levels are defined as low risk I, moderate risk II, high risk III, and extremely high risk IV.

[0039] The beneficial technical effects of the present invention are:

[0040] The present invention integrates the advantages of subjective and objective weighting methods, combines subjective judgment based on actual problems with theoretical calculations based on objective data to determine the comprehensive weights of indicators, tries to make the weights of each indicator consistent with the actual importance, improves the credibility of the indicator weights, and improves the accuracy of the evaluation results. The present invention can evaluate the earthquake damage risk of the tunnel in the preliminary design stage, and can make targeted designs in the design stage according to the risk level, reduce the risk of tunnel collapse, and reduce the harm caused by earthquakes. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a diagram of the index system for assessing the earthquake damage risk level of mountain tunnels.

[0042] Figure 2 This is a classification diagram of earthquake damage risk levels for mountain tunnels. DETAILED DESCRIPTION

[0043] The present invention is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0044] A method for assessing the earthquake damage risk level of a mountain tunnel of the present invention comprises the following steps:

[0045] Step 1: Investigate earthquake events at home and abroad, conduct statistical analysis on tunnels that have suffered earthquake damage, and establish a tunnel earthquake risk assessment indicator system.

[0046] The stability of tunnel surrounding rock is greatly affected by its own strength and integrity. Generally speaking, the lower the surrounding rock grade, the more likely it is to become unstable and cause earthquake disasters during an earthquake. Weathering will reduce the mechanical properties of the surrounding rock, and the degree of weathering has a great relationship with the stability of the surrounding rock. If the strata at the entrance and exit of the tunnel are loose or the slope angle is large, the slope collapse and rockfall caused by the earthquake may cause cracking and damage of the tunnel door, blockage of the tunnel entrance and other disasters.

[0047] The condition of the tunnel lining itself, including the tunnel disease situation, tunnel burial depth and size, etc., all determine whether the lining can withstand the earthquake and maintain its integrity when an earthquake occurs; tunnel diseases include cavities, cracks, water leakage behind the lining, etc., which will reduce the bearing capacity of the structure and thus reduce the seismic performance of the tunnel. Statistics on earthquake damage to tunnels around the world show that the extent of earthquake damage to the tunnel is related to the tunnel burial depth, and the span of the tunnel will also affect its seismic characteristics. The seismic intensity of the tunnel site reflects the average level of ground vibration strength in the region when an earthquake occurs. The higher the seismic intensity, the greater the damage that may occur when an earthquake occurs, and poor geology will aggravate the destructive power of an earthquake.

[0048] In summary, the factors for earthquake risk assessment of mountain tunnels can be divided into three categories: geological conditions of the tunnel site, tunnel status, structural conditions and earthquakes; among them, the geological conditions of the tunnel site include the surrounding rock grade, surrounding rock weathering and tunnel entrance slope angle; the tunnel status includes the maximum tunnel burial depth, tunnel disease conditions and cross-section size; structural conditions and earthquakes include the length of the fault fracture zone, the earthquake intensity of the tunnel site and the adverse geology of the tunnel site. Figure 1 shown.

[0049] Step 2: Introduce the subjective and objective comprehensive weighting method, calculate the entropy value of each indicator according to the variation degree of the selected indicator, and perform normalization processing:

[0050]

[0051]

[0052] Among them, P ij represents the weight of the jth tunnel under the i-th evaluation index, r ij represents the value of the i-th evaluation index of the j-th tunnel, and x and y represent the number of evaluation indexes and the number of tunnels.

[0053] The entropy weight (objective weight) of each evaluation index is calculated according to the following formula:

[0054]

[0055] Invite n experts in the industry to score, construct a judgment matrix and use hierarchical analysis method, use the geometric mean method to obtain the weight vector, and multiply each row of the judgment matrix:

[0056]

[0057] In the formula, x t Represents the elements of each row of the judgment matrix.

[0058] right Normalize and get the subjective weight W of each indicator i ;

[0059]

[0060] Step 3: Determine the risk assessment level; Combine the relevant specifications of tunnel seismic design and engineering practice to determine different earthquake risk assessment levels. The earthquake risk assessment level is defined as low risk (I), medium risk (II), high risk (III), and extremely high risk (IV). For specific classification, see Figure 2 .

[0061] Step 4: Use the distance function to calculate the comprehensive weight of the evaluation index according to the following formula:

[0062]

[0063] In the formula, x t Represents the elements of each row of the judgment matrix;

[0064] right Normalize and get the subjective weight W of each indicator i ;

[0065]

[0066] Step 3: Determine the risk assessment level; determine different earthquake risk assessment levels based on relevant tunnel seismic design specifications and engineering practice;

[0067] Step 4: Use the distance function to calculate the comprehensive weight of the evaluation index according to the following formula:

[0068]

[0069]

[0070] Where α and β represent the weights obtained by the analytic hierarchy process and the adjustment coefficients multiplied by the weights obtained by the improved entropy weight method.

[0071] The comprehensive weight of the evaluation index is a linear combination of the results obtained by calculating the subjective weight and the objective weight:

[0072]

[0073] Step 5: Determine the correlation function; the correlation function expresses the degree of membership of each indicator of the object to be evaluated with respect to each evaluation level. The correlation degree of the indicator is calculated according to the definition of distance in extenics. The calculation formula is:

[0074]

[0075] In the formula, ρ(u i ,U ij ) represents u i with U ij =[a ij ,b ij ], the calculation method is according to formula (10):

[0076]

[0077] D(u i ,U ij ,U ip ) represents point u i About interval U ij and interval U ip The place value of The calculation method is according to formula (11). The position value and distance can quantitatively express the position relationship between the point and the interval;

[0078]

[0079] In the formula, u i is the value of the object element to be evaluated after normalization, U ij is the normalized classical domain, U ip is the normalized section area; a ij is the lower bound of the classical domain, b ij is the upper bound of the classical domain.

[0080] Step 6: Determine the tunnel earthquake damage risk level; obtain the comprehensive correlation degree K under risk level J through the correlation degree and the corresponding weight coefficient j (p):

[0081]

[0082] Where: i Represents the weight coefficient of the i-th evaluation index; K j (u i ) represents the correlation degree of the i-th evaluation index at level J.

[0083] K of the matter-element p to be evaluated j The larger the (p) value, the smaller the deviation of the indicator from the evaluation level. j0 (p) = max[K j (p)(j=1,2,…,m)], then the seismic risk of the tunnel to be evaluated is level j0;

[0084]

[0085] j * is the grade variable of the tunnel to be evaluated, reflecting the degree to which P is biased toward the adjacent grade. * =2.6, which means that p belongs to the second level and tends to the third level.

Claims

1. A method for assessing the earthquake risk level of mountain tunnels, characterized in that: The following steps are involved: Step 1: Investigate earthquake events at home and abroad, conduct statistical analysis on tunnels that have suffered earthquake damage, and establish an indicator system for tunnel earthquake risk assessment; Step 2: Introduce the subjective and objective comprehensive weighting method, calculate the entropy value of each indicator according to the variation degree of the selected indicator, and perform normalization processing: Among them, P ij represents the weight of the jth tunnel under the i-th evaluation index, r ij represents the value of the i-th evaluation index of the j-th tunnel, x and y represent the number of evaluation indexes and the number of tunnels; The entropy weight, i.e., the objective weight, of each evaluation index is calculated according to the following formula: Invite n experts in the industry to score, construct a judgment matrix and use hierarchical analysis method, use the geometric mean method to obtain the weight vector, and multiply each row of the judgment matrix: In the formula, x t Represents the elements of each row of the judgment matrix; right Normalize and get the subjective weight W of each indicator i ; Step 3: Determine the risk assessment level; determine different earthquake risk assessment levels based on relevant tunnel seismic design specifications and engineering practices; Step 4: Use the distance function to calculate the comprehensive weight of the evaluation index according to the following formula: In the formula, α and β represent the weights obtained by the hierarchical analysis method and the adjustment coefficients multiplied by the weights obtained by the improved entropy weight method; The comprehensive weight of the evaluation index is a linear combination of the results obtained by calculating the subjective weight and the objective weight: Step 5: Determine the correlation function; the correlation function expresses the degree of membership of each indicator of the object to be evaluated with respect to each evaluation level. The correlation degree of the indicator is calculated according to the definition of distance in extenics. The calculation formula is: In the formula, ρ(u i ,U ij ) represents u i with U ij =[a ij ,b ij ], the calculation method is according to formula (10): D(u i ,U ij ,U ip ) represents point u i About interval U ij and interval U ip The place value of The calculation method is according to formula (11). The position value and distance can quantitatively express the position relationship between the point and the interval; In the formula, u i is the value of the object element to be evaluated after normalization, U ij is the normalized classical domain, U ip is the normalized section area; a ij is the lower bound of the classical domain, b ij is the upper bound of the classical domain; Step 6: Determine the tunnel earthquake damage risk level; obtain the comprehensive correlation degree K under risk level J through the correlation degree and the corresponding weight coefficient j (p): Where: i represents the weight coefficient of the i-th evaluation index; K j (u i ) represents the correlation degree of the i-th evaluation index at level J; K of the matter-element p to be evaluated j The larger the (p) value, the smaller the deviation of the indicator from the evaluation level. j0 (p) = max[K j (p)(j=1,2,…,m)], then the seismic risk of the tunnel to be evaluated is level j0; j * is the grade variable of the tunnel to be evaluated, reflecting the degree to which P is biased towards the adjacent grade.

2. A method for assessing the earthquake risk level of a mountain tunnel according to claim 1, characterized in that: The earthquake risk assessment indicators are divided into three categories: geological conditions of the tunnel site, tunnel status, structural conditions and earthquakes; among them, the geological conditions of the tunnel site include surrounding rock grade, surrounding rock weathering conditions and tunnel entrance slope angle; the tunnel status includes the maximum burial depth of the tunnel, tunnel disease conditions and cross-sectional size and form; the structural conditions and earthquakes include the length of the fault's fracture zone, the earthquake intensity of the tunnel site and the poor geology of the tunnel site.

3. A method for assessing earthquake damage risk level of mountain tunnels according to claim 1, characterized in that: The earthquake risk assessment levels are defined as low risk I, moderate risk II, high risk III, and extremely high risk IV.

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