A comprehensive assessment method for determining the impact of adjacent construction on existing tunnels

Abstract

The present invention discloses a comprehensive assessment method for determining the impact of proximity construction on existing tunnels, comprising the following steps: Step S1, establishing an attribute set of the existing tunnel structure and the surrounding environment of the tunnel; Step S2, obtaining the value of each attribute in the attribute set under different proximity levels through numerical simulation, model testing, field testing, etc.; Step S3, fitting the functional relationship between each specific attribute and the proximity level; Step S4, standardizing the original functional relationship in combination with the hierarchical assessment standards of each attribute in the attribute set; Step S5, obtaining a comprehensive score using the hierarchical analysis method or other methods to complete the hierarchical assessment of the impact of proximity construction on existing tunnels. The present invention has diverse evaluation angles and a wide range of applications. It can comprehensively consider the impact of multiple attributes of existing tunnels under proximity construction and obtain an assessment system with unified evaluation standards, which has strong guiding significance.

Description

Technical Field

[0001] The present invention belongs to the technical field of underground engineering, and in particular relates to a comprehensive evaluation method for determining the impact of adjacent construction on an existing tunnel. Background Art

[0002] As my country's urban rail transit network continues to improve, construction work around existing tunnels is becoming increasingly frequent. This can cause structural deformation or damage, which can seriously impact rail transit operations. Generally speaking, the closer construction is to existing tunnels, the greater the impact. Therefore, if we can quantitatively characterize the impact of adjacent construction and categorize impact zones based on proximity, we can predict project risks, providing important guidance.

[0003] Existing methods for assessing the impact of adjacent construction on existing tunnels often rely on a single evaluation metric, or analyze the same issue multiple times using different metrics to develop targeted proximity zones. However, a single metric can only reflect a single aspect of the structural safety status or environmental impact, lacking comprehensiveness and adapting to today's increasingly complex and restrictive engineering requirements. Therefore, new technical approaches are needed to address these shortcomings. Summary of the Invention

[0004] In order to solve the above-mentioned technical problems, the present invention provides a comprehensive assessment method for determining the impact of adjacent construction on existing tunnels. The method aims to use multiple evaluation criteria to analyze the impact of adjacent construction on existing tunnels and obtain a comprehensive classification that can meet various control requirements. This method can be applied to the impact analysis under different engineering requirements and scientifically and accurately evaluate engineering risks.

[0005] In order to achieve the above object, the technical solution adopted by the present invention includes:

[0006] Step S1: Establishing an attribute set of the existing tunnel structure and the surrounding environment of the tunnel, wherein the attributes include the internal force of the existing tunnel structure, the additional stress of the existing tunnel structure, the deformation and deformation rate of the existing tunnel, the surface settlement and settlement rate, the surface uplift and uplift rate, the plastic state of the soil and the connectivity state of the plastic zone, the displacement of a specific area, and the differential displacement of a designated area;

[0007] Step S2: determining the value of each attribute in the attribute set at different proximity levels, wherein the proximity level refers to the absolute distance or relative distance between the proximate construction site and the existing tunnel structure;

[0008] Step S3, fitting the functional relationship between each specific attribute and the degree of proximity;

[0009] Step S4: combining the grading standards of each attribute in the attribute set, standardizing the functional relationship in step S3, wherein the standardization includes eliminating the difference in the values of different attributes through a constructor method, so that the constructed functions have the same function value at the proximity threshold;

[0010] Step S5: Based on the attribute values obtained under the constructor, a comprehensive score is calculated to complete the graded assessment of the impact of adjacent construction on the existing tunnel.

[0011] According to an embodiment of the present invention, in step S2, the value of each attribute in the attribute set at different proximity levels is determined by numerical simulation, model test or field test.

[0012] According to an embodiment of the present invention, the functional relationship in step S3 is a fitting function of the attribute value and the degree of proximity, which takes the form of an exponential function with an intercept:

[0013] I=f(x)=Ae Bx +c

[0014] Where:

[0015] I is the value of an attribute in the attribute set;

[0016] x is the degree of proximity;

[0017] A, B, and C are the unknown coefficients of the fitting.

[0018] According to the implementation scheme of the present invention, in step S4, the grading assessment standard includes the control value and warning value of the attribute in the existing specification, the impact grading value of the attribute obtained by the engineering analogy method, and the restriction value of the attribute in the special project. According to the grading assessment standard value, the grading assessment is divided into multiple levels, and based on the attribute value corresponding to the dividing boundary, multiple proximity thresholds are obtained by inverse calculation according to the fitting function.

[0019] According to an embodiment of the present invention, the graded assessment is divided into three levels, corresponding to strong impact, weak impact, and no impact of adjacent construction, and two proximity thresholds are obtained by inverse calculation based on the fitting function.

[0020] According to an embodiment of the present invention, in step S4, the constructed function is a function whose linear trend is consistent with the fitting function and whose calculated values at two proximity thresholds are equal to 1 and 2 respectively, and adopts the following exponential function form:

[0021]

[0022] Where:

[0023] α I is a certain attribute value after standardization;

[0024] k is the unknown coefficient. The specific value is obtained by solving the problem based on the property that the calculated values of the constructor at the proximity threshold are equal to 1 and 2 respectively:

[0025]

[0026] Among them, x1 and x2 are two proximity thresholds.

[0027] According to the embodiment of the present invention, in step S5, the comprehensive score refers to the calculated value obtained by superimposing each attribute value according to a certain weight, which is specifically expressed as:

[0028]

[0029] Where:

[0030] I c Calculate the comprehensive score of each attribute;

[0031] n is the number of attributes involved in the calculation of the comprehensive score;

[0032] ω i is the weight of the i-th attribute;

[0033] α I,i is the normalized attribute value of the i-th attribute.

[0034] According to the embodiment of the present invention, the grading assessment in step S5 is to grade the impact of the adjacent construction according to the relationship between the calculated comprehensive score and 1 and 2. The comprehensive score inherits the property that the normalized function is equal to 1 and 2 at the proximity threshold. Therefore, when the comprehensive score I c >2, the adjacent construction has a strong impact on the existing tunnel; when the attribute value is 1 c <2, the adjacent construction has a weak impact on the existing tunnel; when the attribute value I c When the pressure is less than 1, the adjacent construction will have no impact on the existing tunnel.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] (1) Diverse evaluation angles and strong engineering guidance significance. The present invention comprehensively considers multiple attributes, can quantitatively evaluate the impact of adjacent construction, and obtain a unified standard evaluation score, thereby comprehensively considering the control requirements of engineering construction in multiple aspects and using a relatively simple comparison method to obtain specific classification, which has strong guiding significance.

[0037] ​(2) The method is highly applicable and has a wide range of uses. This method is suitable for evaluating the impact of various types of adjacent construction on existing tunnels, such as the impact of adjacent foundation pit excavation, adjacent tunnel construction, temporary building construction, and other common working conditions on existing tunnels. It has a wide range of applications. At the same time, the evaluation method can flexibly adjust the engineering properties of interest and is suitable for engineering assessments in different strata and with different actual control requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of a flow chart of a comprehensive assessment method for determining the impact of adjacent construction on an existing tunnel according to an embodiment of the present invention;

[0039] Figure 2 is a functional relationship diagram of horizontal tunnel construction proximity and various attributes according to an embodiment of the present invention;

[0040] Figure 3 is a graph showing the relationship between the construction proximity of a horizontal tunnel and the normalized functions of various attributes according to an embodiment of the present invention;

[0041] Figure 4 Schematic diagram of a partition function for the comprehensive impact of adjacent parallel tunnel construction on existing tunnels according to an embodiment of the present invention;

[0042] Figure 5 This is a comprehensive assessment zoning for the impact of adjacent parallel tunnel construction on existing tunnels according to the implementation plan of the present invention. DETAILED DESCRIPTION

[0043] The present invention will be further described below in detail through specific embodiments in conjunction with the accompanying drawings. The illustrated contents are used to fully illustrate the contents of the present invention but are not used to limit the present invention.

[0044] Taking the impact of adjacent parallel construction of a new tunnel on an existing shield tunnel as an example, the comprehensive evaluation method for determining the impact of adjacent construction on an existing tunnel of the present invention is described in detail. Figure 1 As shown, the method of the present invention is carried out according to the following steps:

[0045] Step S1: Establishing an attribute set of the existing tunnel structure and the tunnel surrounding environment:

[0046] The key control indicators of interest in the project are ground settlement above the existing shield tunnel, the ellipticity of the existing shield tunnel, and the maximum stress in the existing shield tunnel. These three attributes form an attribute set for subsequent assessment. It should be understood that different projects may determine different attributes and attribute sets.

[0047] Step S2: By means of numerical simulation, model test, field test, etc., the values of each attribute in the attribute set at different proximity levels are obtained:

[0048] This embodiment uses numerical simulation methods to establish finite element models for the conditions of different tunnel clearances when a new tunnel is parallel to an existing tunnel. Based on the model calculation results, the values of each attribute in the attribute set are summarized. Finite element simulation is well known in the art and will not be described in detail here.

[0049] Step S3: Fitting the functional relationship between each specific attribute and the degree of proximity:

[0050] According to the calculation results in step S2, the attributes and the tunnel clearance are fitted in the form of an exponential function with an intercept, that is:

[0051] I=f(x)=Ae Bx +c

[0052] Where:

[0053] I is the value of a certain attribute in the attribute set. In this embodiment, I s Represents relative surface subsidence, I E Indicates the relative change value of ellipticity, I P is the relative change value of the maximum stress;

[0054] x is the degree of proximity, which in this embodiment is the ratio of the tunnel clearance S to the existing tunnel outer diameter D;

[0055] A, B, and C are the unknown coefficients of the fitting.

[0056] By using the least squares method and solving the unknown coefficients, we can get the relationship between a certain attribute and the degree of proximity. The unknown coefficients of relative surface settlement are A = 1.86168, B = -1.52968, and C = 0.77075. Similarly, we can get the relative change value of ellipticity I E , maximum stress relative change value I P The corresponding undetermined coefficients are shown in the attached Figure 2 shown.

[0057] Step S4: standardize the fitting function based on the grading criteria of each attribute in the attribute set:

[0058] Taking the classification standard of relative surface settlement as an example, it can be considered that I s When the settlement of the two tunnels exceeds 2, the settlement of the two tunnels has exceeded twice that of a single tunnel, which has a strong impact on the ground surface. s =2 is the boundary between strong and weak influence. Similarly, when I s When it is less than 1.5, it can be considered that the additional settlement caused by the new tunnel is less than half of the impact of the original tunnel construction, which can be used as the boundary between weak and no impact. s =2 and I s= 1.5, the threshold values of the proximity level are calculated to be x1 = 0.27 and x2 = 0.56. Based on the proximity level threshold, the constructor can be set as follows:

[0059]

[0060] Where:

[0061] α s is the relative surface settlement value after standardized processing;

[0062] k s is the unknown coefficient of the relative surface settlement function.

[0063] Constructor α s Trend, line type and fitting function I s By setting g(x1) = 2 and g(x2) = 1, the constructor can be made equal to 1 and 2 at the classification threshold, which is convenient for the subsequent evaluation of the comprehensive score. Based on this constraint, the undetermined coefficients in the constructor can be solved:

[0064]

[0065] For the relative surface settlement value, the undetermined coefficient k = 0.97233, and the standardized influence function is α I =g(x)=3.72336e -1.52968x -0.4585. Similarly, the relative change value of ellipticity I can be obtained E , maximum stress relative change value I P The corresponding undetermined coefficient k E 、k P And the normalized function α E , α P The results are as follows Figure 3 As shown in the figure, the function values of different attributes have a strong influence when they are greater than or equal to 2, no influence when they are less than or equal to 1, and a weak influence when they are between 1 and 2.

[0066] Step S5: Use the analytic hierarchy process or other methods to obtain a comprehensive score and complete the graded assessment of the impact of adjacent construction on existing tunnels:

[0067] In order to comprehensively consider the three attributes in the attribute set, the expert scoring method believes that the weights of all influence degrees in this example are equal, that is, the weights are expressed as:

[0068] ω i =1 / n

[0069] Where:

[0070] ω i is the weight of the i-th attribute;

[0071] n is the number of attributes involved in the calculation of the comprehensive score.

[0072] The unified score can be calculated based on the weight distribution, which is specifically expressed as:

[0073]

[0074] Where:

[0075] I c Calculate the comprehensive score of each attribute;

[0076] α I,i is the normalized attribute value of the i-th attribute.

[0077] Thus, the evaluation score of each attribute can be obtained. The comprehensive score inherits the property that the normalized function is equal to 1 or 2 at the classification threshold. Therefore, when the comprehensive score I c >2, the adjacent construction has a strong impact on the existing tunnel; when the attribute value is 1 c <2, the adjacent construction has a weak impact on the existing tunnel; when the attribute value I c When the pressure is less than 1, the adjacent construction will have no impact on the existing tunnel.

[0078] By combining the comprehensive scores of the new tunnel at different positions in the parallel tunnel, we can get a schematic diagram of the partition function of the impact of the parallel tunnel construction on the existing tunnel, as shown in the attached figure. Figure 4 Furthermore, the proximity threshold under the comprehensive judgment criterion can be calculated based on the comprehensive score to obtain a classification diagram of the impact of the existing tunnel on the new parallel tunnel, as shown in the attached figure. Figure 5 shown.

[0079] The above description of the embodiments is intended to facilitate understanding and application of the present invention by those skilled in the art. It will be apparent to those skilled in the art that various modifications to these embodiments can be readily made and the general principles described herein can be applied to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the embodiments described herein. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be considered within the scope of protection of the present invention.​

Claims

1. A comprehensive assessment method for determining the impact of adjacent construction on existing tunnels, characterized in that: The following steps are involved: Step S1: establishing an attribute set of the existing tunnel structure and the surrounding environment of the tunnel, wherein the attributes include the internal force of the existing tunnel structure, the additional stress of the existing tunnel structure, the deformation and deformation rate of the existing tunnel, the surface settlement and settlement rate, the surface uplift and uplift rate, the plastic state of the soil and the connectivity state of the plastic zone, the displacement of a specific area, and the differential displacement of a designated area; Step S2: determining the value of each attribute in the attribute set at different proximity levels, wherein the proximity level is the absolute distance or relative distance between the proximate construction site and the existing tunnel structure; Step S3, fitting the functional relationship between each specific attribute and the degree of proximity; Step S4: combining the grading standards of each attribute in the attribute set, standardizing the functional relationship in step S3. The standardization includes eliminating the difference in the values of different attributes through a constructor method, so that the constructors have the same function value at the proximity threshold. Step S5: Based on the attribute values obtained in the constructor, a comprehensive score is calculated to complete the graded assessment of the impact of adjacent construction on the existing tunnel; The functional relationship in step S3 is a fitting function between the attribute value and the degree of proximity, and is in the form of an exponential function with an intercept: I=f(x)=Ae Bx +c Where: I is the value of a certain attribute in the attribute set; x is the degree of closeness; A, B, C are the coefficients to be determined for fitting; Among them, in step S4, the grading assessment standard includes the control value and warning value of the attribute in the existing specification, the impact grading value of the attribute obtained by the engineering analogy method, and the restriction value of the attribute in special engineering. According to the grading assessment standard value, the grading assessment is divided into multiple levels, and based on the attribute value corresponding to the dividing boundary, multiple proximity thresholds are obtained by inverse calculation according to the fitting function.

2. A comprehensive assessment method for determining the impact of adjacent construction on an existing tunnel according to claim 1, characterized in that: In step S2, the value of each attribute in the attribute set at different proximity levels is determined by numerical simulation, model test or field test.

3. The comprehensive assessment method for determining the impact of adjacent construction on an existing tunnel according to claim 1, characterized in that: The grading assessment is divided into three levels, corresponding to strong impact, weak impact, and no impact of nearby construction. Two proximity thresholds are obtained by inverse calculation based on the fitting function.

4. A comprehensive assessment method for determining the impact of adjacent construction on an existing tunnel according to claim 3, characterized in that: In step S4, the constructor is a function whose linear trend is consistent with the fitting function and whose calculated values at two proximity thresholds are equal to 1 and 2 respectively, and adopts the following exponential function form: Where: α I is a certain attribute value after standardization; k is the unknown coefficient. The specific value is obtained by solving the problem based on the property that the calculated values of the constructor at the proximity threshold are equal to 1 and 2 respectively: Among them, x1 and x2 are two proximity thresholds.

5. The comprehensive assessment method for determining the impact of adjacent construction on an existing tunnel according to claim 1, characterized in that: In step S5, the comprehensive score refers to the calculated value obtained by superimposing each attribute value according to a certain weight, which is specifically expressed as: Where: I c Calculate the comprehensive score of each attribute; n is the number of attributes involved in the calculation of the comprehensive score; ω i is the weight of the i-th attribute; α I,i is the normalized attribute value of the i-th attribute.

6. A comprehensive assessment method for determining the impact of adjacent construction on an existing tunnel according to claim 4, characterized in that: The grading evaluation in step S5 is to grade the impact of adjacent construction according to the relationship between the calculated comprehensive score and 1 and 2. The comprehensive score inherits the property that the normalized function is equal to 1 and 2 at the proximity threshold. Therefore, when the comprehensive score I c >2, the adjacent construction has a strong impact on the existing tunnel; when the comprehensive score is 1 c <2, the adjacent construction has a weak impact on the existing tunnel; when the comprehensive score I c When the pressure is less than 1, the adjacent construction will have no impact on the existing tunnel.​

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