Shield tunnel construction disturbance range determination method

Abstract

The invention discloses a method for determining the disturbance range of shield tunnel construction, and aims to solve the problem that the disturbance range cannot be pre-judged through a real-time monitoring result in an existing method. The method comprises the following steps: selecting a typical monitoring section, selecting a proper position for arranging a sensor, and monitoring soil mass deep layer horizontal displacement and ground surface settlement of a shield tunneling machine passing through the section; meanwhile, establishing a numerical calculation model in the shield tunneling process, and verifying the numerical calculation model according to a field monitoring result; calculating and analyzing the influence of shield tunnel construction on ground surface settlement according to shield tunneling conditions under different strata and burial depth conditions; the Peck formula is corrected by fitting the ground surface settlement data; according to the corrected Peck formula, ground surface settlement of shield tunnel construction is predicted, and the disturbance range of the ground surface settlement is determined. According to the method, the prediction precision of deformation and settlement of the shield tunnel construction stratum under different stratum conditions and burial depth conditions can be improved, and the purpose of judging the disturbance range is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of geotechnical engineering, and in particular to a method for determining a disturbance range in shield tunnel construction. Background Art

[0002] Shield tunnel construction disturbs the soil around the tunnel, which in turn causes ground settlement within a certain area of ​​the tunnel. Once the displacement and deformation exceed the predetermined range, it will endanger the safety of nearby ground buildings and underground pipelines. The ground disturbance effect of shield tunnel construction and its impact on the surrounding environment have always been a hot topic of concern in academia and industry.

[0003] In order to strictly control the impact of shield tunnel construction on surrounding buildings and structures, ensure the normal use of existing buildings and structures along the line and the smooth progress of subway construction when the subway passes through, it is necessary to reasonably determine the disturbance range of shield tunnel construction. At present, the surface settlement deformation of different sections is achieved by real-time monitoring of the strata under shield construction, and the disturbance range of the corresponding interval is determined by the surface settlement deformation of different sections. However, the deficiency of this method is that it is impossible to predict the disturbance range through real-time monitoring results. In addition, the traditional Peck formula is used to predict surface settlement, which also requires a large amount of monitoring results to correct the formula.

[0004] Therefore, based on the limited real-time monitoring results, by taking advantage of the advantages of numerical calculation, a large number of simulation calculations of surface settlement of shield construction under different formation conditions and different burial depth conditions can be carried out. Based on the numerical calculation results, the original Peck formula is corrected, and then the corrected Peck formula is used to predict the disturbance range of shield tunnel construction. Compared with the traditional disturbance determination method, this method is a more scientific and efficient method for determining the disturbance range of shield tunnel construction. Summary of the invention

[0005] In view of the above-mentioned technical deficiencies, the purpose of the present invention is to provide a method for determining the disturbance range of shield tunnel construction, which is based on the displacement monitoring data of a limited number of measuring points and combined with numerical calculation methods to obtain an accurate Peck settlement prediction formula and its settlement curve suitable for the formation conditions, and determine the disturbance range of shield tunnel construction based on the modified Peck formula.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: A method for determining a disturbance range of shield tunnel construction comprises the following steps: Step 1: Select the shield tunnel construction displacement monitoring section and set up surface settlement monitoring points and deep horizontal displacement monitoring points; Step 2: Monitor the surface settlement and deep horizontal displacement of the soil from the shield construction section 50m away to the shield construction section 50m away from the monitoring section; analyze and process the monitoring data to obtain the foundation settlement and deformation characteristics under the shield construction condition; Step 3: Taking the monitoring section as the object, establish a numerical calculation model and carry out numerical simulation calculation of surface deformation during shield construction; Step 4: Based on the surface settlement deformation and deep horizontal deformation characteristics of the soil obtained in step 3, the numerical calculation model is verified; Step 5: Change the stratum structure and soil parameters of the numerical calculation model, calculate the shield tunneling conditions under different strata and burial depths, and analyze the impact of shield tunnel construction on surface settlement; Step 6: Fit the surface settlement data obtained by numerical calculation, correct the Peck formula, and obtain the correction coefficient under different rock and soil parameters and different burial depth conditions; Step 7: Based on the ground conditions of shield construction, the surface settlement of shield tunnel construction is predicted according to the modified Peck formula, and the disturbance range of shield tunnel construction is determined based on the result.

[0007] Furthermore, the arrangement of displacement monitoring points in step 1 is specifically as follows: arranging elevation reference points for vertical displacement observation outside the scope of the project influence, arranging displacement measurement points on the monitoring cross section perpendicular to the tunnel centerline, arranging 9-15 monitoring points in total, and the monitoring points are arranged symmetrically about the tunnel axis, with a spacing of 3 to 6 m between the measuring points; at the same time, drilling a depth measuring tube at a distance of 5 to 10 m from the axis on the ground, measuring every 1.0 m along the entire length of the guide groove from bottom to top, and carrying out deep horizontal displacement monitoring of the soil, with the drilling depth being greater than the tunnel floor depth.

[0008] Furthermore, the analysis and processing of the monitoring data in step 2 is specifically as follows: monitoring the deep horizontal displacement of the soil and the surface settlement when the shield machine passes through the section, the monitoring interval is 50 meters before and after the shield excavation face is away from the monitoring section, and the maximum ground settlement curve in the cross-sectional direction and the distribution characteristics of the horizontal displacement of the soil at different depths are obtained by analysis.

[0009] Furthermore, the establishment of the numerical calculation model in step 3 is specifically as follows: a three-dimensional model is constructed using numerical software, the length of which is greater than the length of the monitoring interval (generally 100m long), the width of which is greater than the total width of the measuring points on the monitoring cross section (generally 50m wide), and the model soil layers are divided according to the results of on-site drilling cataloging.

[0010] Furthermore, the verification of the numerical calculation model in step 4 is specifically as follows: determining the parameters of each soil layer of the model based on a comprehensive analysis of the on-site soil layer identification, in-situ testing and geotechnical test results during exploration, selecting an appropriate solver and solution algorithm to run the simulation, extracting the node displacement data of each location of the model monitoring point corresponding to the on-site monitoring point, and verifying the accuracy of the model by comparing the numerical calculation results with the on-site monitoring results and optimizing the model mesh quality.

[0011] Furthermore, the calculation of the influence of tunnel construction on surface settlement in step 5 is specifically as follows: in order to predict the surface settlement characteristics of shield tunnel construction under different geological conditions in the region, a large number of numerical calculations are performed on working conditions with different geological structures, rock and soil parameters and different burial depths.

[0012] Furthermore, the Peck formula correction in step 6 is specifically as follows: according to the calculation results of the surface settlement characteristics under different shield construction conditions, the surface lateral settlement trough curves under different working conditions are fitted based on the least squares method, and the formation loss rate and the width parameters of the settlement trough in the Peck formula are corrected.

[0013] Furthermore, the construction disturbance range determination of step 7 is specifically as follows: according to the formation conditions of the construction section, the modified Peck formula is applied, and the correction coefficient corresponding to the formation conditions is selected to predict the surface settlement of the shield tunnel construction; according to the predicted surface settlement curve, combined with the sensitivity of deformation of the surrounding buildings of the tunnel section and the allowable value of deformation, the disturbance range of the shield construction is determined.

[0014] The beneficial effects of the present invention are as follows: The method of the present invention uses the monitoring results of the ground settlement of the typical section and the deep soil displacement as the model verification data to perform numerical simulation on the shield construction of the typical section; on this basis, a large number of numerical simulations are performed by taking advantage of the numerical simulation to calculate the shield excavation conditions under different strata and burial depths, and the traditional Peck formula is corrected according to the numerical calculation results, and the surface settlement is predicted using the corrected Peck formula to determine the disturbance range. The method of the present invention can predict the disturbance range while reducing the workload of on-site monitoring. It is a more scientific and efficient method for determining the disturbance range of shield tunnel construction, and has a large application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 A flow chart of a method for determining a disturbance range in shield tunnel construction according to the present invention; Figure 2 Schematic diagram of the arrangement of monitoring points in a typical monitoring section of the present invention, where H is the distance between the surface settlement monitoring points; h is the distance between the inclinometer tube and the tunnel centerline; Figure 3 A numerical model diagram of shield tunneling construction in an embodiment of the present invention; Figure 4 It is a comparison diagram of the settlement curves of the shield tunnel construction numerical simulation and on-site monitoring in the present invention.

[0017] Description of reference numerals: 1. Surface settlement observation point; 2. Inclinometer tube; 3. Tunnel floor; 4. Tunnel centerline. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Example 1 like Figure 1 As shown, a method for determining the disturbance range of shield tunnel construction includes the following steps: Step 1: Select the shield tunnel construction displacement monitoring section, and set up surface settlement monitoring points and deep horizontal displacement monitoring points; A monitoring section is set perpendicular to the tunnel axis; On the selected monitoring section, the elevation reference points for vertical displacement observation are arranged outside the project influence range; Arrange displacement measurement points on the monitoring cross section, with a total of 9-15 monitoring points arranged symmetrically about the tunnel axis, with a spacing of 3-6m between the points; Drill holes at a certain distance (5-10 m) from the axis on the monitoring cross section, and record the formation information, structural characteristics, lithological characteristics, etc. The drilling depth is greater than the tunnel floor depth, and the hole diameter is slightly larger than the outer diameter of the buried inclinometer tube. The inclinometer tube connected on the ground is placed in the borehole, and the gap between the inclinometer tube and the borehole is backfilled with fine sand or cement and bentonite mortar. The measurement is taken every 1.0 m along the entire length of the guide groove from bottom to top to carry out deep horizontal displacement monitoring of the soil.

[0020] Step 2: Monitor each measuring point of a typical section during construction. The main monitoring interval is from 50m from the shield construction monitoring section to 50m from the shield construction monitoring section. Analyze and process the monitoring data to obtain the foundation settlement deformation characteristics under shield construction conditions; Set up sensor monitoring intervals, within 50m before and after the excavation face and the monitoring section, to monitor surface settlement and deep horizontal displacement, with observations made once in the morning and once in the evening during the monitoring cycle; The collected monitoring data are processed and analyzed to obtain the cumulative settlement curve of each measuring point on the monitoring section and the maximum settlement distribution characteristics of each measuring point, and the horizontal displacement distribution curve of the deep soil body; Step 3: Taking the monitoring section as the object, a three-dimensional numerical calculation model is established to carry out numerical simulation calculation of surface deformation during shield construction to obtain the ground deformation law of shield tunneling; A three-dimensional numerical calculation model is established based on the monitoring section drilling data, profile data, and plane geological map. The model length is greater than the monitoring interval length (generally 100m long), the width is greater than the total width of the measuring points on the monitoring cross section (generally 50m wide), and the depth is greater than the depth of the inclined hole in the section. The model soil layer is divided based on the stratigraphic information and lithological characteristics recorded by the on-site drilling; The model grid division takes calculation accuracy into consideration and adopts uneven grid. A denser grid is used in the area near the excavated tunnel. The grid gradually becomes sparser from the tunnel centerline to both sides of the model, with a minimum of 1.0 m and a maximum of 10.0 m. There is one grid layer every 1.0 m in the depth direction.

[0021] Step 4: Based on the foundation settlement deformation data of the monitoring section under shield construction conditions obtained in step 2, the stratum deformation law obtained by numerical calculation in step 3 is verified. If the calculated results are inconsistent with the measured results, the model is optimized and calculated again until they match; Determine the parameters of each soil layer in the model based on comprehensive analysis of on-site soil layer identification, in-situ testing and geotechnical test results during exploration, set boundary conditions based on actual construction environment and conditions, and select appropriate solvers and solution algorithms to run simulations; The node displacement data of each model monitoring point corresponding to the on-site monitoring point are extracted, and the accuracy of the model is verified by comparing the numerical calculation results with the on-site monitoring results and optimizing the model mesh quality.

[0022] Step 5: On the basis that the calculated results are consistent with the measured results, the stratum structure and soil parameters of the numerical calculation model are changed, the shield tunneling conditions under different strata and burial depths are calculated, and the impact of shield tunnel construction on surface settlement is analyzed; Step 6: Fit the surface settlement data obtained by numerical calculation, correct the Peck formula, and obtain the correction coefficient under different rock and soil parameters and different burial depth conditions; The calculation results of surface settlement characteristics under different shield construction conditions are analyzed. Based on the law that the surface lateral settlement curve conforms to the Gaussian distribution, the Peck formula is used for fitting inversion analysis. The Peck formula is corrected by two important parameters of the Peck formula, namely the settlement trough width coefficient K and the stratum soil loss rate η. Using the data of numerical simulation of surface settlement, according to the fitting results, the maximum surface settlement correction coefficient and the settlement trough width correction coefficient under different working conditions are determined, and then the correction coefficient of Peck's formula under different rock and soil conditions and different burial depths is determined.

[0023] Step 7: Based on the ground conditions of shield construction, the surface settlement of shield tunnel construction is predicted according to the modified Peck formula, and the disturbance range of shield tunnel construction is determined based on the result.

[0024] According to the ground conditions of the construction area, the modified Peck formula is applied, and the correction coefficient corresponding to the ground conditions is selected to predict the surface settlement of shield tunnel construction. Based on the predicted surface settlement curve, combined with the sensitivity of deformation of buildings around the tunnel section and the allowable value of deformation, the disturbance range of shield construction is determined.

[0025] Taking the shield construction of a certain section of the Xuzhou Metro Line 3 Phase II project as an example, a typical section of the construction section was selected as the object. The strata of the selected section are mixed fill, silt, clay, strongly weathered limestone, and moderately weathered limestone. The tunnel burial depth is 11.13m. Measurement points are arranged on the selected section. The measurement point arrangement is as follows: Figure 2 The distance between the surface settlement measurement points is 3 m, and the distance between the inclinometer tube and the tunnel centerline is set to 5 m.

[0026] A three-dimensional numerical calculation model is constructed with the selected typical section as the research object, such as Figure 3 The model soil layers are divided based on the stratigraphic information and lithological characteristics recorded by on-site drilling. The parameters of each soil layer in the model are determined by comprehensive analysis of on-site soil layer identification, in-situ testing and geotechnical test results during exploration. The numerical calculation results are compared with the on-site measured results. Figure 4As shown in the figure, the absolute error between the simulation data and the monitoring data is no more than 2 mm, which is relatively consistent. The numerical calculation results show that the settlement curve caused by tunnel excavation conforms to the normal distribution curve and can be fitted by the Peck formula. Under the conditions of further changing the stratum structure and soil parameters of the numerical calculation model, the shield excavation conditions under different strata and burial depths are calculated, the surface settlement data obtained by numerical calculation are fitted, and the Peck formula is corrected to obtain the correction coefficient under different rock and soil parameters and different burial depths. Based on the corrected Peck formula, the surface settlement of shield tunnel construction can be predicted, and the disturbance range of shield construction can be determined based on the predicted surface settlement curve. Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for determining the disturbance range of shield tunnel construction, characterized in that: The following steps are involved: Step 1: Select the shield tunnel construction displacement monitoring section and set up surface settlement monitoring points and deep horizontal displacement monitoring points; Step 2: Monitor the surface settlement and deep horizontal displacement of the soil from the shield construction section 50m away to the shield construction section 50m away from the monitoring section; analyze and process the monitoring data to obtain the foundation settlement and deformation characteristics under the shield construction condition; Step 3: Taking the monitoring section as the object, establish a numerical calculation model and carry out numerical simulation calculation of surface deformation during shield construction; Step 4: Based on the surface settlement deformation and deep horizontal deformation characteristics of the soil obtained in step 3, the numerical calculation model is verified; Step 5: Change the stratum structure and soil parameters of the numerical calculation model, calculate the shield tunneling conditions under different strata and burial depths, and analyze the impact of shield tunnel construction on surface settlement; Step 6: Fit the surface settlement data obtained by numerical calculation, correct the Peck formula, and obtain the correction coefficient under different rock and soil parameters and different burial depth conditions; Step 7: Based on the ground conditions of shield construction, the surface settlement of shield tunnel construction is predicted according to the modified Peck formula, and the disturbance range of shield tunnel construction is determined based on the result.

2. The method for determining the disturbance range of shield tunnel construction according to claim 1, characterized in that: The arrangement of displacement monitoring points in step 1 is specifically as follows: arranging elevation reference points for vertical displacement observation outside the scope of the project influence, arranging displacement measurement points on the monitoring cross section perpendicular to the tunnel centerline, arranging 9-15 monitoring points in total, and the monitoring points are arranged symmetrically about the tunnel axis, with a spacing of 3-6m between the measuring points; at the same time, drilling a depth measuring incline tube at a distance of 5-10m from the axis on the ground, measuring and reading it every 1.0m along the entire length of the guide groove from bottom to top, and carrying out deep horizontal displacement monitoring of the soil, with the drilling depth being greater than the tunnel floor depth.

3. A method for determining the disturbance range of shield tunnel construction according to claim 1 or 2, characterized in that: The analysis and processing of the monitoring data in step 2 is specifically as follows: monitoring the deep horizontal displacement of the soil and the surface settlement when the shield machine passes through the section, the monitoring interval is 50 meters before and after the shield excavation face is away from the monitoring section, and the maximum ground settlement curve in the cross-sectional direction and the distribution characteristics of the horizontal displacement of the soil at different depths are obtained by analysis.

4. The method for determining the disturbance range of shield tunnel construction according to claim 1, characterized in that: The establishment of the numerical calculation model in step 3 is specifically as follows: a three-dimensional model is constructed using numerical software, the length of which is greater than the length of the monitoring interval, the width of which is greater than the total width of the measuring points on the monitoring cross section, and the model soil layers are divided according to the on-site drilling cataloging results.

5. The method for determining the disturbance range of shield tunnel construction according to claim 1, characterized in that: The verification of the numerical calculation model in step 4 is specifically as follows: determining the parameters of each soil layer of the model based on a comprehensive analysis of the results of on-site soil layer identification, in-situ testing and geotechnical testing during exploration, selecting an appropriate solver and solution algorithm to run the simulation, extracting the node displacement data of each location of the model monitoring point corresponding to the on-site monitoring point, and verifying the accuracy of the model by comparing the numerical calculation results with the on-site monitoring results and optimizing the model mesh quality.

6. The method for determining the disturbance range of shield tunnel construction according to claim 1, characterized in that: The calculation of the impact of tunnel construction on surface settlement in step 5 is specifically as follows: in order to predict the surface settlement characteristics of shield tunnel construction under different geological conditions in the area, a large number of numerical calculations are performed on working conditions with different geological structures, rock and soil parameters and different burial depths.

7. The method for determining the disturbance range of shield tunnel construction according to claim 1, characterized in that: The Peck formula correction in step 6 is specifically as follows: according to the calculation results of the surface settlement characteristics generated under different shield construction conditions, the surface lateral settlement trough curves under different working conditions are fitted based on the least squares method, and the formation loss rate and the width parameters of the settlement trough in the Peck formula are corrected.

8. The method for determining the disturbance range of shield tunnel construction according to claim 1, characterized in that: The construction disturbance range determination of step 7 is specifically as follows: according to the formation conditions of the construction section, the modified Peck formula is applied, and the correction coefficient corresponding to the formation conditions is selected to predict the surface settlement of the shield tunnel construction; according to the predicted surface settlement curve, combined with the sensitivity of deformation of the surrounding buildings of the tunnel section and the deformation allowable value, the disturbance range of the shield construction is determined.

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