Method and system for judging influence of foundation pit excavation influence factors on tunnel deformation

Abstract

The invention relates to a method and system for judging the influence of foundation pit excavation influence factors on tunnel deformation. The method comprises the following steps that working conditions are set according to the relative positions of a tunnel and a foundation pit; foundation pit excavation influence factors are set for each working condition, and the foundation pit excavation influence factors are classified; actual measurement data are obtained, and different types of foundation pit excavation influence factor databases are established according to the classification; and performing data processing on each group of foundation pit excavation influence factor database, establishing a'tunnel deformation-influence factor 'image, and obtaining influence trends of different foundation pit excavation influence factors on tunnel deformation. Compared with the prior art, the influence trend of different foundation pit excavation influence factors on tunnel deformation in the foundation pit excavation process is comprehensively analyzed.

Description

Technical Field

[0001] The invention relates to the technical field of foundation pit engineering, and in particular to a method and a system for judging the influence of foundation pit excavation influencing factors on tunnel deformation. Background Art

[0002] At present, the traditional prediction methods for the deformation of adjacent tunnels induced by foundation pit excavation mainly include model tests, field measurement analysis, theoretical calculations, numerical simulations and other methods. For example, patent application CN 116227267A discloses a method for predicting the displacement of the influence zone of foundation pit excavation and the existing tunnel outside the pit, which involves the field of geotechnical engineering technology and includes the following steps: determining the foundation pit, tunnel parameters and site geology, hydrology and other information in the project to be evaluated; using numerical simulation methods to obtain the maximum displacement of the tunnel at different positions outside the pit under different foundation pit excavation depths He and maximum lateral displacement of the retaining structure δhm; determining the tunnel displacement contour range corresponding to the three-level control standards of tunnel displacement, that is, the influence zone; defining and obtaining the quantitative determination parameters of the influence zone range; analyzing the influence of He and δhm on the influence zone range, and proposing a prediction method for the influence zone range under arbitrary He and δhm conditions; predicting the displacement that may be caused by the tunnel according to the actual influence zone where the tunnel is located; determining the excavation influence zone according to the basic parameters of the foundation pit, and then realizing a simplified prediction of the tunnel displacement according to the actual influence zone where the tunnel is located. According to the different relative positions between the tunnel and the foundation pit, it is divided into two situations: the excavation of the foundation pit on the side of the tunnel and the excavation of the foundation pit above the tunnel. In the actual production and life process, the influence mechanism of the foundation pit excavation on the deformation of the adjacent tunnel is relatively complex, which is affected by many factors such as the size of the foundation pit, the relative position of the tunnel and the foundation pit, and the construction method of the retaining structure. The influencing mechanisms and laws on the overall displacement of the tunnel and the convergence of the pipe segments are not the same. Existing studies have failed to comprehensively consider the influence trend of different influencing factors on tunnel deformation during the foundation pit excavation process based on the statistics and fitting of measured data. Summary of the invention

[0003] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a method and system for judging the influence of foundation pit excavation influencing factors on tunnel deformation, thereby realizing a comprehensive analysis of the influence trend of different foundation pit excavation influencing factors on tunnel deformation during foundation pit excavation.

[0004] The purpose of the present invention can be achieved by the following technical solutions:

[0005] A method for determining the influence of factors affecting foundation pit excavation on tunnel deformation comprises the following steps:

[0006] Set the working conditions according to the relative positions of the tunnel and the foundation pit;

[0007] Setting the factors affecting foundation pit excavation for each of the working conditions, and classifying the factors affecting foundation pit excavation;

[0008] Acquire measured data, and establish a database of factors affecting foundation pit excavation of different categories according to the classification;

[0009] Data processing is performed on each group of the foundation pit excavation influencing factors database to establish a "tunnel deformation-influencing factors" image, and the influence trend of different foundation pit excavation influencing factors on tunnel deformation is obtained.

[0010] Furthermore, the working conditions include deformation of the side tunnel caused by foundation pit excavation and deformation of the lower tunnel caused by foundation pit excavation.

[0011] Furthermore, the factors affecting foundation pit excavation include ground conditions, foundation pit excavation size, retaining wall and internal support layout, and the relative position of the tunnel and the foundation pit.

[0012] Furthermore, the foundation pit excavation dimensions include the foundation pit excavation depth H p , the excavation width b of the foundation pit along the direction perpendicular to the tunnel and the excavation width a of the foundation pit along the direction parallel to the tunnel.

[0013] Furthermore, the retaining wall and internal support layout include the retaining wall embedding depth and the internal support vertical layout density.

[0014] Furthermore, the relative position of the tunnel and the foundation pit includes the horizontal clearance L between the tunnel and the foundation pit. t and the height difference H between the tunnel vault and the foundation pit bottom t .

[0015] Furthermore, the tunnel deformation includes the horizontal displacement of the tunnel δ h , tunnel vertical displacement δ v and the horizontal radial extension ΔD of the tunnel.

[0016] Furthermore, the embedding depth of the retaining wall, the vertical arrangement density of the internal support, and the horizontal clearance L between the tunnel and the foundation pit are t and the height difference H between the tunnel vault and the foundation pit bottom t Divide by the excavation depth H p Perform normalization.

[0017] Furthermore, the data processing is to perform data mining on the measured data.

[0018] According to another aspect of the present invention, a system for determining the influence of factors affecting foundation pit excavation on tunnel deformation is provided, comprising:

[0019] The working condition setting module is used to set the working condition according to the relative position of the tunnel and the foundation pit;

[0020] The influencing factor classification module is used to set the influencing factors of foundation pit excavation for each working condition and classify the influencing factors of foundation pit excavation;

[0021] An influencing factor database establishment module is used to obtain measured data and establish a database of influencing factors of different categories of foundation pit excavation according to the classification;

[0022] The data processing module is used to process the data of each group of foundation pit excavation influencing factors database, establish the "tunnel deformation-influencing factors" image, and obtain the influence trend of different foundation pit excavation influencing factors on tunnel deformation.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. Based on the measured data of engineering cases, the present invention summarizes and analyzes the influencing factors of various foundation pit excavation under different working conditions during the foundation pit excavation process, comprehensively determines the key factors affecting the tunnel deformation during the foundation pit excavation process, and reduces engineering risks.

[0025] 2. The present invention performs data mining on the database of factors affecting foundation pit excavation, establishes a "tunnel deformation-influencing factor" image, and qualitatively analyzes the influence trend of different foundation pit excavation influencing factors on tunnel deformation according to the rules presented by the "tunnel deformation-influencing factor" image, which helps to adjust the size of each foundation pit excavation influencing factor during the foundation pit excavation process, optimize the construction plan, and guide production and life. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of the method flow for determining the influence of factors affecting foundation pit excavation on tunnel deformation;

[0027] Figure 2 is a schematic diagram of the foundation pit and the side tunnel, where (2a) is a plan view of the foundation pit and the side tunnel, where a is the excavation width of the foundation pit parallel to the tunnel, b is the excavation width of the foundation pit perpendicular to the tunnel, D is the outer diameter of the tunnel, and L t is the horizontal clearance between the tunnel haunch and the foundation pit, (2b) is the cross-sectional view of the foundation pit and the side tunnel, where H p is the excavation depth of the foundation pit, a is the excavation width of the foundation pit parallel to the tunnel direction, b is the excavation width of the foundation pit perpendicular to the tunnel direction, l is the length of the retaining wall, d is the thickness of the retaining wall, h i is the installation depth of the vertical support, D is the outer diameter of the tunnel, L t It is the horizontal clear distance between the tunnel haunch and the foundation pit;

[0028] Figure 3 is a schematic diagram of the foundation pit and the tunnel below, where (3a) is a plan view of the foundation pit and the tunnel below, where l1 is the length of the tunnel passing through the foundation pit, α is the angle between the tunnel and the intersection of the foundation pit, l2 is the distance from the center of the foundation pit plane to the tunnel axis, and (3b) is a cross-sectional view of the foundation pit and the tunnel below, where H pis the excavation depth of the foundation pit, is the excavation width of the foundation pit parallel to the tunnel direction, b is the excavation width of the foundation pit perpendicular to the tunnel direction, l is the length of the retaining wall, d is the thickness of the retaining wall, h i is the installation depth of the vertical support, D is the outer diameter of the tunnel, H t It is the height difference between the tunnel vault and the bottom of the foundation pit;

[0029] Figure 4 The data images are of the deformation of the lateral tunnel caused by the change of the vertical density of the internal support during the excavation of the foundation pit in different strata, wherein (4a) is the data image of the horizontal displacement of the tunnel caused by the change of the vertical density of the internal support in soft clay, silt soil and gravel and pebble (hard clay)-weathered rock, (4b) is the data image of the vertical displacement of the tunnel caused by the change of the vertical density of the internal support in soft clay, silt soil and gravel and pebble (hard clay)-weathered rock, (4c) is the data image of the horizontal radial elongation of the tunnel caused by the change of the vertical density of the internal support in soft clay and silt soil;

[0030] Figure 5 These are data images of the deformation of the tunnel below caused by foundation pit excavation in different strata, among which (5a) is a data image of the vertical displacement of the tunnel in soft clay, silt and gravel (hard clay)-weathered rock, (5b) is a data image of the vertical radial elongation of the tunnel in soft clay and silt, and (5c) is a data image of the horizontal radial convergence of the tunnel in soft clay and silt. DETAILED DESCRIPTION

[0031] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0032] Example 1

[0033] This embodiment provides a method for determining the influence of factors affecting foundation pit excavation on tunnel deformation, such as Figure 1 As shown, the following steps are included:

[0034] S1. Set the working conditions according to the relative positions of the tunnel and the foundation pit.

[0035] According to domestic and foreign engineering cases, two working conditions are set: deformation of the side tunnel caused by foundation pit excavation and deformation of the lower tunnel caused by foundation pit excavation.

[0036] S2. Set the factors affecting foundation pit excavation for each working condition and classify them.

[0037] For each working condition, four factors affecting the excavation of the foundation pit are set: ground conditions, excavation size of the foundation pit, layout of retaining walls and internal supports, and relative position of the foundation pit and tunnel. Figure 2 As shown, Figure 2 (2a) is the plan view of the foundation pit and the side tunnel. Figure 2 (2b) is a cross-sectional view of the foundation pit and the side tunnel. Figure 3 As shown, Figure 3 (3a) is the plan view of the foundation pit and the tunnel below. Figure 3 (3b) is a cross-sectional view of the foundation pit and the tunnel below.

[0038] Among them, the excavation dimensions of the foundation pit include the excavation depth of the foundation pit, the excavation width of the foundation pit in the direction perpendicular to the tunnel, and the excavation width of the foundation pit in the direction parallel to the tunnel; the layout of the retaining wall and the internal support includes the embedding depth of the retaining wall and the vertical layout density of the internal support; the relative position of the foundation pit and the tunnel includes the horizontal clear distance between the tunnel and the foundation pit and the height difference between the tunnel vault and the bottom of the foundation pit; the dimensions of the foundation pit and the tunnel, the layout of the retaining wall and the internal support, and the relative position of the foundation pit and the tunnel are shown in the figure below: Figure 2 and Figure 3 As shown. Among them, H p is the excavation depth of the foundation pit, a is the excavation width of the foundation pit parallel to the tunnel direction, and b is the excavation width of the foundation pit perpendicular to the tunnel direction; l is the length of the retaining wall, and d is the thickness of the retaining wall (the pile row is equivalent to the bending stiffness); h i is the installation depth of the vertical support of the i-th column; D is the outer diameter of the tunnel, L t is the horizontal clear distance between the tunnel haunch and the foundation pit (if the two are not completely parallel, the minimum distance is taken to reflect the maximum deformation of the tunnel), H t is the height difference between the tunnel vault and the bottom of the foundation pit (positive when the tunnel vault depth is less than the foundation pit excavation depth); δ h is the maximum horizontal displacement of the tunnel (positive towards the inside of the pit), δ v is the maximum vertical displacement of the tunnel (uplift is positive, settlement is negative), ΔD is the maximum horizontal radial extension of the tunnel; for the schematic diagram of the foundation pit and the tunnel below, l1 is the length of the tunnel passing through the foundation pit, α is the angle between the tunnel and the intersection of the foundation pit, and l2 is the distance from the center of the foundation pit plane to the tunnel axis.

[0039] S3. Obtain measured data and establish a database of factors affecting excavation of different types of foundation pits.

[0040] Establish a "tunnel deformation-influencing factors" database. Tunnel deformation includes: tunnel horizontal displacement δ h , tunnel vertical displacement δ v , horizontal radial extension of the tunnel ΔD.

[0041] Through literature research, 70 engineering cases of tunnel side excavation (75 tunnels in total) were obtained, and the factors affecting the excavation of the foundation pit in each case were recorded. The tunnel deformation of all cases was measured on site, which can reflect the combined effect of multiple factors affecting the excavation of the foundation pit. The factors affecting the excavation of the foundation pit include: stratum conditions, excavation depth H p , the excavation width of the foundation pit parallel to the tunnel direction α, the excavation width of the foundation pit perpendicular to the tunnel direction b, the embedding depth of the retaining wall (lH p ) / H p , vertical layout density of internal supports Horizontal clearance between tunnel and foundation pit L t / H p and the height difference H between the tunnel vault and the bottom of the foundation pit t / H p , where the retaining wall embedding depth, the vertical layout density of the internal support, the horizontal clearance between the tunnel and the foundation pit, and the height difference between the tunnel vault and the foundation pit bottom are all calculated by dividing the representative value of step S2 by the foundation pit excavation depth H p To achieve the normalization effect; according to the principle of comprehensive testing, there are 2×3×8=48 groups of databases.

[0042] Through investigation, 41 engineering cases of foundation pit excavation above tunnels (52 tunnels in total) were obtained, and the influencing factors of foundation pit excavation in each case were recorded. The tunnel deformation of all cases were measured on site, and the influencing factors of foundation pit excavation were the same as above. There were 2×3×8=48 sets of databases.

[0043] S4. Perform data processing on each group of foundation pit excavation influencing factors database, establish a "tunnel deformation-influencing factors" image, and obtain the influence trend of different foundation pit excavation influencing factors on tunnel deformation.

[0044] Data mining is performed on each group of foundation pit excavation influencing factors database to establish a "tunnel deformation-influencing factor" image, and the influence trend of different foundation pit excavation influencing factors on tunnel deformation is analyzed.

[0045] For the working condition of lateral tunnel deformation caused by foundation pit excavation, the vertical layout density of internal supports is taken as an example to establish the “tunnel deformation-influencing factors” image, such as Figure 4 shown.

[0046] In the image, data of different strata are represented by points of different colors; for images with obvious changing trends, straight lines or curves can be used to represent the trends, such as Figure 4 As shown in (4a), the horizontal displacement of the tunnel decreases as the internal support density increases.

[0047] The tunnel deformation and the corresponding vertical density of the side foundation pit support in three typical strata are as follows: Figure 4 As shown, Figure 4(4a) is a data image of the horizontal displacement of the tunnel caused by the change of the vertical density of the internal support in soft clay, silt soil and gravel pebble (hard clay)-weathered rock. Figure 4 (4b) is a data image of the vertical displacement of the tunnel caused by the change of the vertical density of the internal support in soft clay, silt soil and gravel pebble (hard clay)-weathered rock. Figure 4 (4c) is a data image of the horizontal radial elongation of the tunnel caused by the change of the vertical arrangement density of the internal support in soft clay and silt soil. The tunnel deformation is very small, because the excavation depth of the corresponding case foundation pit does not exceed 9.0m. At the same time, in different strata The increase in tunnel horizontal displacement δ h are significantly reduced. Figure 4 Available, when When the vertical displacement of the tunnel is v Follow Increase and increase, Time δ v Follow Increase and decrease, it can be considered When compared with the internal support density, the excavation depth H p δ v The influence of the vertical displacement of the tunnel is greater. v <0, δ v Follow The change pattern of is not obvious, which may be due to too few samples. There are few cases where ΔD and internal support information are recorded at the same time, and the pattern is not obvious.

[0048] For the deformation of the tunnel below caused by foundation pit excavation, taking the stratum conditions and as an example, a "tunnel deformation-influencing factors" image is established. For those with unclear change trends, their classification can be displayed. According to the different distribution of different color points in the image, it is divided vertically. The deformation of the tunnel below induced by foundation pit excavation in different strata is shown in the figure. Figure 5 As shown, Figure 5 (5a) is a data image of the vertical displacement of the tunnel in soft clay, silt and gravel (hard clay)-weathered rock. Figure 5 (5b) is the data image of the vertical radial extension of the tunnel in soft clay and silt soil. Figure 5 (5c) is a data image of the horizontal radial convergence of the tunnel in soft clay and silt.

[0049] In general, the influence of foundation pit excavation on the tunnel below varies significantly in different strata types. v Generally large, second in silt sand layer, and in gravel and pebble (hard clay)-weathered rock layer. vSmall; ΔD in soft clay and silt sand layers v and ΔD h Similar in size but with fewer samples, no ΔD was recorded in the case of gravel (hard clay)-weathered rock formation v and ΔD h Although the overall influence of stratum type on tunnel deformation is obvious, the discreteness of tunnel deformation values ​​of the same stratum type is also large, indicating that the specific physical and mechanical properties of the soil and other factors such as construction and geometry have a great influence on tunnel deformation.

[0050] Similar analysis ideas are applied to other factors under the two working conditions, and the results are as follows:

[0051] The factors and rules affecting the side tunnel deformation induced by foundation pit excavation are as follows: ① The stratum properties have a great influence on tunnel deformation. In general, the influence of foundation pit excavation on tunnel in different strata is ranked as follows: soft clay stratum > silt sand stratum > gravel and pebble (hard clay)-weathered rock stratum; ② Tunnel deformation increases with the depth of foundation pit excavation H. p ③ The horizontal displacement and vertical displacement of the tunnel increase with the increase of the excavation width a in the direction parallel to the tunnel and the excavation width b in the direction perpendicular to the tunnel; ④ The increase of the retaining wall embedding depth (lH p ) has a certain limiting effect on tunnel deformation, but has no obvious effect when the tunnel is vertically uplifted; ⑤ Increase the density of support erection It has a significant limiting effect on the horizontal displacement of the tunnel, but has no significant effect on limiting the vertical displacement and deformation of the segment; ⑥ The tunnel deformation increases with the horizontal clear distance L between the foundation pit and the tunnel. t , height difference between pit bottom and tunnel vault H t The increase was significantly reduced.

[0052] The factors and rules affecting the deformation of the tunnel induced by the foundation pit excavation are as follows: ① The stratum properties have a great influence on the tunnel deformation. The order of the influence of the foundation pit excavation on the tunnel is: soft clay stratum > silt sand stratum > gravel and pebble (hard clay)-weathered rock stratum; ② The tunnel deformation increases with the depth of the foundation pit excavation H. p and the excavation area A increases; ③ Increase the embedding depth of the retaining wall (lH p ) has no significant effect on the deformation of the tunnel below, increasing the density of support erection Although it can limit the deformation of the tunnel, the effect is not obvious; ④ The deformation of the tunnel increases with the length of the foundation pit l1, and with the distance l2 from the center of the foundation pit plane to the tunnel axis and the height difference H between the pit bottom and the tunnel vault. t decreases with the increase of .

[0053] Example 2

[0054] This embodiment provides a system for determining the influence of factors affecting foundation pit excavation on tunnel deformation, including:

[0055] The working condition setting module is used to set the working condition according to the relative position of the tunnel and the foundation pit;

[0056] The influencing factor classification module is used to set the influencing factors of foundation pit excavation for each working condition and classify them;

[0057] The influencing factor database establishment module is used to obtain measured data and establish a database of influencing factors for different types of foundation pit excavation;

[0058] The data processing module is used to process the data of each group of foundation pit excavation influencing factors database, establish the "tunnel deformation-influencing factors" image, and obtain the influence trend of different foundation pit excavation influencing factors on tunnel deformation.

[0059] Example 3

[0060] This embodiment provides an optimized construction plan based on a method for determining the impact of factors affecting foundation pit excavation on tunnel deformation. The specific optimization method is the same as that of Embodiment 1.

[0061] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for determining the influence of factors affecting foundation pit excavation on tunnel deformation, characterized in that: The following steps are involved: Set the working conditions according to the relative positions of the tunnel and the foundation pit; Setting the factors affecting foundation pit excavation for each of the working conditions, and classifying the factors affecting foundation pit excavation; Acquire measured data, and establish a database of factors affecting foundation pit excavation of different categories according to the classification; Data processing is performed on each group of the foundation pit excavation influencing factors database to establish a "tunnel deformation-influencing factors" image, and the influence trend of different foundation pit excavation influencing factors on tunnel deformation is obtained.

2. The method for determining the influence of factors affecting foundation pit excavation on tunnel deformation according to claim 1, characterized in that: The working conditions include deformation of the side tunnel caused by foundation pit excavation and deformation of the lower tunnel caused by foundation pit excavation.

3. The method for determining the influence of factors affecting foundation pit excavation on tunnel deformation according to claim 1, characterized in that: The factors affecting foundation pit excavation include ground conditions, foundation pit excavation size, retaining wall and internal support layout, and the relative position of the tunnel and the foundation pit.

4. The method for determining the influence of factors affecting foundation pit excavation on tunnel deformation according to claim 3 is characterized in that: The foundation pit excavation dimensions include the foundation pit excavation depth H p , the excavation width b of the foundation pit along the direction perpendicular to the tunnel and the excavation width a of the foundation pit along the direction parallel to the tunnel.

5. The method for determining the influence of factors affecting foundation pit excavation on tunnel deformation according to claim 3 is characterized in that: The retaining wall and internal support layout includes the retaining wall embedding depth and the internal support vertical layout density.

6. The method for determining the influence of factors affecting foundation pit excavation on tunnel deformation according to claim 3 is characterized in that: The relative position of the tunnel and the foundation pit includes the horizontal clearance L between the tunnel and the foundation pit. t and the height difference H between the tunnel vault and the foundation pit bottom t .

7. The method for determining the influence of factors affecting foundation pit excavation on tunnel deformation according to claim 1, characterized in that: The tunnel deformation includes the tunnel horizontal displacement δ h , tunnel vertical displacement δ v and the horizontal radial extension ΔD of the tunnel.

8. The method for determining the influence of factors affecting foundation pit excavation on tunnel deformation according to claim 6, characterized in that: The embedding depth of the retaining wall, the vertical layout density of the internal support, the horizontal clearance L between the tunnel and the foundation pit t and the height difference H between the tunnel vault and the foundation pit bottom t Divide by the excavation depth H p Perform normalization.

9. The method for determining the influence of factors affecting foundation pit excavation on tunnel deformation according to claim 1, characterized in that: The data processing is to perform data mining on the measured data.

10. A system for determining the influence of factors affecting foundation pit excavation on tunnel deformation, characterized in that: include: The working condition setting module is used to set the working condition according to the relative position of the tunnel and the foundation pit; The influencing factor classification module is used to set the influencing factors of foundation pit excavation for each working condition and classify the influencing factors of foundation pit excavation; An influencing factor database establishment module is used to obtain measured data and establish a database of influencing factors of different categories of foundation pit excavation according to the classification; The data processing module is used to process the data of each group of foundation pit excavation influencing factors database, establish the "tunnel deformation-influencing factors" image, and obtain the influence trend of different foundation pit excavation influencing factors on tunnel deformation.

Images