A multi-factor quantitative analysis method for deformation of small-spacing mountain tunnel

Abstract

The application discloses a kind of small clear spacing mountain tunnel deformation multi-factor quantitative analysis method, comprising the following steps: tunnel field monitoring data analysis, tunnel shallow buried section collapse accident simulation, determine the influence degree of each factor on tunnel and stratum and determine the quantitative influence of each factor on tunnel deformation;The present application takes tunnel shallow buried section collapse accident as the breakthrough point, takes field monitoring data and finite element simulation as analysis means, analyzes the ground surface subsidence and tunnel deformation law in the process of tunnel excavation, analyzes the collapse accident of shallow buried section, determines the cause of collapse accident, obtains the correlation degree of each factor on tunnel deformation based on this, carries out correlation deformation quantitative analysis to each factor, obtains the key index of small clear spacing tunnel on influencing factor, can provide accurate theoretical basis for small clear spacing tunnel shallow buried section construction, and help tunnel safety construction and cost saving.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tunnel construction, in particular to a multi-factor quantitative analysis method for deformation of a small-spacing mountain tunnel. BACKGROUND

[0002] China ranks third in the global ranking of national land area, with a land area of 9.6 million square kilometers, vast territory, and various landforms throughout the country. The land area of China is mainly composed of plains, plateaus, hills and mountains, among which the mountainous area accounts for 33%. The infrastructure construction is difficult. As an important part of China's transportation network, expressways bear the heavy burden of realizing traffic modernization and national modernization, and promote the rapid development of China's economy and society. In the construction of expressways, tunnels, as an important part of the transportation line, are increasing in number and total length.

[0003] At present, due to the constraints of objective conditions such as geological conditions, topography, line selection requirements, construction technology and engineering cost factors, small-spacing tunnels are often used in highway engineering. However, compared with traditional tunnel types, small-spacing tunnels have complex stress conditions and are prone to bias pressure in mountainous areas. During the construction of shallow-buried sections of tunnels, landslides and other geological disasters are prone to occur. Therefore, it is of great significance to study the deformation law of surrounding rock and the response of small-spacing tunnels in shallow-buried sections.

[0004] Although the existing small-spacing tunnel deformation research method studies the deformation mechanism and response law of surrounding rock of small-spacing tunnels from different aspects, obtains many valuable results, and determines the mechanical mechanism of small-spacing tunnels and the reasonable process during construction, the number of research results on geological disasters of small-spacing tunnel projects is small, and the disaster evolution mechanism is not studied in depth. The response law of each factor to the tunnel is not analyzed, so the key indicators of the small-spacing tunnel to the influencing factors cannot be obtained, and thus accurate theoretical basis cannot be provided for the construction of the shallow-buried section of the small-spacing tunnel, which cannot help the safe construction of the tunnel and cost saving. Therefore, the present application proposes a multi-factor quantitative analysis method for deformation of a small-spacing mountain tunnel to solve the problems existing in the prior art. SUMMARY

[0005] In view of the above problems, the purpose of the present application is to provide a multi-factor quantitative analysis method for deformation of a small-spacing mountain tunnel to solve the problem that the existing small-spacing tunnel deformation research method does not deeply study the disaster evolution mechanism, so the key indicators of the small-spacing tunnel to the influencing factors cannot be obtained.

[0006] In order to achieve the purpose of the present application, the present application realizes the following technical scheme: a multi-factor quantitative analysis method for deformation of a small-spacing mountain tunnel, comprising the following steps:

[0007] Step one: Theoretical analysis of surrounding rock pressure of the tunnel to be analyzed is performed, and the tunnel site is monitored in combination with tunnel design data, and then the tunnel site monitoring data is collected, analyzed, summarized and concluded;

[0008] Step two: Taking tunnel shallow section collapse as a breakthrough point, the tunnel site data summarized and tunnel deformation theory are combined to analyze the collapse causes, determine the main causes of the tunnel collapse accident, use finite element numerical simulation software to simulate the straight-through surface collapse accident occurring during tunnel construction, extract the numerical simulation results, obtain the deformation characteristics in the tunnel construction process, analyze the tunnel displacement field at different distances before the tunnel excavation collapses, and determine the displacement and stress response when the tunnel collapse accident occurs;

[0009] Step three: According to the displacement and stress response when the tunnel collapse accident occurs, the factors affecting the tunnel deformation and surrounding rock instability are analyzed as control variables, the deformation response law of strata and tunnels to each factor is obtained, and the deformation correlation fitting of each factor is performed based on the data to determine the influence degree of each factor on the tunnel and strata;

[0010] Step four: Using the statistical analysis method of grey correlation analysis-entropy method, the factors affecting the tunnel deformation are quantitatively calculated in relation to the extracted numerical simulation results and the influence degree of each factor on the tunnel and strata, the correlation degree of each factor on the deformation of the tunnel shallow buried section is sorted, the main influencing factor of the tunnel deformation is obtained, and the quantitative influence of each factor on the tunnel deformation is determined.

[0011] Further improvement lies in that in step one, the tunnel site monitoring content includes mandatory items and selected items, the mandatory items include in-hole and out-hole observation during tunnel construction, ground subsidence, vault settlement and horizontal convergence, and the selected items include internal force measurement of steel arch, seepage pressure, tunnel surrounding rock pressure and shaft force of anchor rod.

[0012] Further improvement lies in that in step one, when collecting, analyzing, summarizing and concluding the tunnel site monitoring data, relying on advanced geological prediction, the proportion of tunnel face area of grade III, grade IV and grade V surrounding rock is determined, tunnel deformation data of different surrounding rock grades are summarized and analyzed to determine different deformation stages of tunnel surrounding rock.

[0013] Further improvement lies in that the deformation stage of the tunnel surrounding rock is divided into a growth stage and a stable stage, and the growth stage is divided into an increasing stage and a slow increasing stage.

[0014] Further improvement lies in that: in the step two, the whole process of tunnel construction is reproduced in the finite element numerical simulation software, the three-dimensional inversion of the collapse accident during the tunnel construction is carried out, the whole process of tunnel deformation and surrounding rock damage when the tunnel collapse accident occurs is determined by combining the simulation data and the cause analysis.

[0015] Further improvement lies in that: in the step three, the factors influencing the tunnel deformation and the surrounding rock instability include overbreak height, face offset distance and surrounding rock elastic modulus, and the overbreak height, the face offset distance and the surrounding rock elastic modulus are set with different gradients when the control variable analysis is carried out.

[0016] Further improvement lies in that: in the step three, when the influence degree of each factor on the tunnel and the stratum is determined, the stratum settlement, the intercalated rock and the tunnel deformation are taken as the judgment criteria, the deformation curves under different working conditions are obtained, the surface and the tunnel deformation data are extracted and summarized, the response law of different factors on the tunnel and the stratum is obtained, and the characteristic values of each factor are obtained.

[0017] Further improvement lies in that: in the step four, when the deformation correlation quantitative calculation is carried out, the tunnel vault deformation and the horizontal convergence are taken as the judgment basis, the correlation degree of each factor on the tunnel deformation is calculated, and the correlation degrees are sorted from large to small.

[0018] The beneficial effects of the present application are that: the present application takes the tunnel shallow buried section collapse accident as the breakthrough point, takes the field monitoring data and the finite element simulation as the analysis means, analyzes the surface settlement and the tunnel deformation law in the tunnel excavation process, analyzes the collapse accident of the shallow buried section, determines the cause of the collapse accident, obtains the correlation degree of each factor on the tunnel deformation on the basis, and uses the control variable method to analyze the influence of different factors on the tunnel deformation, and uses the grey correlation analysis-entropy method to quantitatively analyze the correlation deformation of each factor, obtains the key index of the influence factors of the small clear distance tunnel, can provide accurate theoretical basis for the shallow buried section construction of the small clear distance tunnel, and helps the tunnel safety construction and cost saving. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only show some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative labor.

[0020] Figure 1 is a method flowchart of the present application;

[0021] Figure 2 is a monitoring point schematic diagram of the tunnel in the embodiment of the present application;

[0022] Figure 3 is a schematic diagram of a tunnel portal segment top ground surface monitoring point in the embodiment of the present application;

[0023] Figure 4 is a tunnel portal ground surface monitoring comparison diagram in the embodiment of the present application. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0025] Referring to Figure 1 , Figure 2 , Figure 3 , Figure 4 , the embodiment provides a multi-factor quantitative analysis method for deformation of a small-clearance mountain tunnel, comprising the following steps:

[0026] Step 1: Taking the Huangjiaceng Tunnel in Weihai City, Shandong Province as a research object, the surrounding rock pressure of the Huangjiaceng Tunnel is theoretically analyzed, and a targeted monitoring scheme is proposed in combination with the tunnel design data to monitor the tunnel site, wherein the tunnel site monitoring content includes mandatory items and selected items, the mandatory items include in-hole and out-hole observation during tunnel construction, ground subsidence, vault settlement and horizontal convergence, the selected items include internal force measurement of steel arches, seepage pressure, tunnel surrounding rock pressure and axial force of anchor rods, and then the tunnel site monitoring data is collected, analyzed, summarized and concluded, relying on the advanced geological prediction, it is determined that the proportion of grade V surrounding rock in the Huangjiaceng Tunnel is high, and the proportions of grade III and grade IV surrounding rock are low, the tunnel deformation data of different surrounding rock grades are summarized and analyzed, it is determined that the surrounding rock deformation of the Huangjiaceng Tunnel is divided into two stages, a growth stage and a stable stage, wherein the growth stage is divided into a rapid growth stage and a slow growth stage, the tunnel deformation under grade V surrounding rock is larger than that under grade III and grade IV, and the time required for the stable state is longer, the differences in ground subsidence at the tunnel portal under different buried depths are compared, it is determined that the deformation of the pilot tunnel of the small-clearance tunnel at the portal segment of the Huangjiaceng Tunnel is greatly affected by the following tunnel, and the influence of the following tunnel on the pilot tunnel gradually decreases with the increase of the buried depth;

[0027] Step two: Taking the tunnel collapse of the shallow buried section as the breakthrough point, combined with the summary of the tunnel site data and the tunnel deformation theory, the cause of the collapse is analyzed, and the main cause of the tunnel collapse accident is determined to be the excavation near the tunnel, the nature of the surrounding rock and overbreak. The finite element numerical simulation software MIDAS GTS NX is used to simulate the straight-through surface collapse accident occurring during tunnel construction, and the numerical simulation results are extracted. The whole process of tunnel construction is reproduced in the finite element numerical simulation software, and the three-dimensional inversion of the tunnel collapse accident during construction is carried out. Combined with the simulation data and cause analysis, the whole process of tunnel deformation and surrounding rock failure when the tunnel collapse accident occurs is determined, the deformation characteristics in the process of tunnel construction are obtained, the displacement field of the tunnel at different distances before the tunnel excavation to the collapse is analyzed, and the displacement and stress response when the tunnel collapse accident occurs are determined, which corresponds to the analysis and determination of the cause of the collapse;

[0028] Step three: According to the displacement and stress response when the tunnel collapse accident occurs, the factors affecting the tunnel deformation and surrounding rock instability, including overbreak height, face offset distance and surrounding rock elastic modulus, are set to different gradients and controlled variable analysis is carried out. The deformation response law of the stratum and the tunnel to each factor is obtained. Based on the data, the deformation correlation fitting of each factor is determined, and the influence degree of each factor on the tunnel and the stratum is determined. When determining the influence degree of each factor on the tunnel and the stratum, the stratum settlement, the intermediate rock and the tunnel deformation are used as the judgment criteria, the deformation curves under different working conditions are obtained, the surface and tunnel deformation data are extracted and summarized, the response law of different factors on the tunnel and the stratum is obtained, and the characteristic value of each factor is obtained.

[0029] Step four: Using the statistical analysis method of grey correlation analysis-entropy method, the numerical simulation results and the influence degree of each factor on the tunnel and the stratum are used to carry out deformation correlation quantitative calculation of the factors affecting the tunnel deformation. The correlation degree of each factor on the deformation of the tunnel shallow buried section is sorted, the main influencing factor of the tunnel deformation is obtained, and the quantitative influence of each factor on the tunnel deformation is determined. When carrying out the deformation correlation quantitative calculation, the tunnel vault deformation and horizontal convergence are used as the judgment basis, the correlation degree of each factor on the tunnel deformation is calculated, and the correlation degree is sorted from large to small.

[0030] The vault settlement monitoring point of Huangjiaceng Tunnel is located at the position of the tunnel vault, and there is one measuring point. According to different construction methods, different measuring lines are set, and there are at most 6 measuring lines. The horizontal convergence is measured by the horizontal convergence measuring line, and the horizontal convergence measuring line is set according to the different construction methods. Figure 2 The following is the monitoring point schematic diagram of Huangjiaceng Tunnel, including the vault settlement monitoring point and the horizontal convergence measuring line.

[0031] The following is the monitoring point schematic diagram of Huangjiaceng Tunnel, including the vault settlement monitoring point and the horizontal convergence measuring line. Figure 3As shown in the drawings, ground monitoring points are arranged at the top of the tunnel portal section, and there are 15 monitoring points in total, wherein the interval of monitoring points 1-6 and 10-15 is 5 m, and the interval of monitoring points 6-10 is 2.5 m. A 2.5 m monitoring interval is arranged at monitoring points 6-10. The ground settlement detection generally adopts a strip-type and cross-type observation network, and the observation points are arranged using the method of steel nails and concrete piles.

[0032] The internal monitoring of Huangjiacun tunnel mainly includes vault settlement and horizontal convergence. The monitoring points are located directly above the vault of the tunnel excavation section. In the monitoring scheme, the vault settlement of the tunnel is monitored at a monitoring section of 5 m. There are 44 monitoring sections in the left-line tunnel and 42 monitoring sections in the right-line tunnel. Considering that there are too many monitoring points, the vault settlement and horizontal convergence under different surrounding rock grades are extracted as Figure 4 As shown in the drawings, according to the monitoring data, from Figure 4 It can be seen that the tunnel deformation trends under the three surrounding rock grades are roughly the same, and the curves are approximately logarithmic functions, which experience a process of rapid increase and gradual stability. Therefore, the entire settlement process is divided into two stages. The first stage is the growth stage, and the second stage is the stable stage. The first stage is divided into the rapid increase stage and the slow increase stage.

[0033] In special sections, it is also necessary to supplement the selected monitoring items and comprehensively judge the stability of the surrounding rock during construction. At the same time, the tunnel geological conditions in front of the working face are determined by using the advanced geological prediction method. The necessary monitoring items and monitoring scheme during tunnel construction are shown in Table 1.

[0034] Table 1: Necessary monitoring items of tunnel site monitoring

[0035]

[0036] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A multi-factor quantitative analysis method for deformation of mountain tunnels with small clearance, characterized in that, The method comprises the following steps: Step one: theoretically analyze the surrounding rock pressure of the tunnel to be analyzed, monitor the tunnel site in combination with the tunnel design data, and then collect, analyze, summarize and conclude the tunnel site monitoring data; Step two: taking the tunnel shallow-buried section collapse as the breakthrough point, combining the summarized tunnel site data and tunnel deformation theory to analyze the collapse causes, determining the main causes of the tunnel collapse accident, using finite element numerical simulation software to simulate the straight-through surface collapse accident occurring during tunnel construction, extracting the numerical simulation results to obtain the deformation characteristics in the tunnel construction process, analyzing the tunnel displacement field at different distances before the tunnel collapse, and determining the displacement and stress response when the tunnel collapse accident occurs; Step three: based on the displacement and stress response when the tunnel collapse accident occurs, the factors affecting the tunnel deformation and surrounding rock instability are analyzed by control variable analysis, the deformation response law of the stratum and the tunnel to each factor is obtained, and the deformation correlation fitting of each factor is carried out based on the data to determine the influence degree of each factor on the tunnel and the stratum; Step four: using the statistical analysis method of grey correlation analysis-entropy method, the factors affecting the tunnel deformation are quantitatively calculated by deformation correlation according to the extracted numerical simulation results and the influence degree of each factor on the tunnel and the stratum, the correlation degree of each factor on the deformation of the tunnel shallow-buried section is sorted, the main influencing factor of the tunnel deformation is obtained, and the quantitative influence of each factor on the tunnel deformation is determined. In step one, the tunnel site monitoring content includes mandatory items and selected items, the mandatory items include in-hole and out-hole observation during tunnel construction, ground subsidence, vault settlement and horizontal convergence, and the selected items include internal force measurement of steel arch, seepage pressure, tunnel surrounding rock pressure and shaft force of anchor rod. In step one, when collecting, analyzing, summarizing and concluding the tunnel site monitoring data, rely on advanced geological prediction to determine the proportion of tunnel face area of grade III, grade IV and grade V surrounding rock, and summarize and analyze the deformation data of different surrounding rock grades to determine the different deformation stages of tunnel surrounding rock.

2. The method according to claim 1, wherein the method is characterized by: The deformation stages of the tunnel surrounding rock are divided into growth stage and stable stage, and the growth stage is divided into rapid growth stage and slow growth stage.

3. The method according to claim 1, wherein the method is characterized by: In step two, the whole tunnel construction process is reproduced in the finite element numerical simulation software, the tunnel collapse accident during tunnel construction is three-dimensionally inversed, and the whole process of tunnel deformation and surrounding rock damage when the tunnel collapse accident occurs is determined in combination with the simulation data and cause analysis.

4. The method according to claim 1, wherein the method is characterized by: In step three, the factors affecting the tunnel deformation and surrounding rock instability include overbreak height, face offset distance and surrounding rock elastic modulus, and different gradients of overbreak height, face offset distance and surrounding rock elastic modulus are set when the control variable analysis is carried out.

5. The method according to claim 1, wherein the method is characterized by: In step three, when determining the influence degree of each factor on the tunnel and the stratum, the stratum settlement, intermediate rock and tunnel deformation are used as the judgment criteria to obtain the deformation curves under different working conditions, the surface and tunnel deformation data are extracted and summarized, the response law of different factors on the tunnel and the stratum is obtained, and the characteristic values of each factor are obtained.

6. The method according to claim 1, wherein the method is characterized by: In step four, when performing quantitative calculations of deformation correlation, the deformation of the tunnel arch and horizontal convergence are used as the criteria to calculate the correlation degree of each factor with the tunnel deformation, and the correlation degree is sorted from largest to smallest.

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