A method for determining the disturbance range during shield tunnel construction

Abstract

This invention discloses a method for determining the disturbance range during shield tunnel construction, aiming to solve the problem that existing methods cannot predict the disturbance range based on real-time monitoring results. The method involves selecting a typical monitoring section and deploying sensors at appropriate locations to monitor the deep horizontal displacement of the soil and surface settlement as the shield machine passes through that section. Simultaneously, a numerical calculation model of the shield tunneling process is established and verified based on on-site monitoring results. The impact of shield tunnel construction on surface settlement is calculated and analyzed under different geological conditions and burial depths. The Peck formula is modified by fitting surface settlement data. Based on the modified Peck formula, the surface settlement during shield tunnel construction is predicted, thus determining the disturbance range. This method improves the accuracy of predicting ground deformation and settlement during shield tunnel construction under different geological conditions and burial depths, thereby achieving the goal of determining the disturbance range.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering technology, specifically a method for determining the disturbance range during shield tunnel construction. Background Technology

[0002] The construction of shield tunnels disturbs the surrounding soil, leading to ground settlement within a certain area. If the displacement and deformation exceed predetermined limits, it can jeopardize nearby buildings and underground pipelines. The ground disturbance effects of shield tunneling and their impact on the surrounding environment have long been a hot topic of concern for both academia and industry.

[0003] To strictly control the impact on surrounding buildings and structures during shield tunnel construction and ensure the normal use of existing buildings and structures along the subway line and the smooth progress of subway construction, it is essential to rationally determine the disturbance range of shield tunnel construction. Currently, surface settlement deformation at different cross-sections is achieved through real-time monitoring of the strata beneath the shield tunnel. The disturbance range for corresponding sections is determined based on the surface settlement deformation at different cross-sections. However, this method has the drawback of being unable to predict the disturbance range based on real-time monitoring results. Furthermore, predicting surface settlement using the traditional Peck formula also requires extensive monitoring data to refine the formula.

[0004] Therefore, based on limited real-time monitoring results, and leveraging the advantages of numerical computation, numerous simulation calculations of surface settlement during shield tunneling construction under different geological conditions and burial depths can be performed. The original Peck formula is then modified based on the numerical calculation results, and the modified Peck formula is used to predict the disturbance range during shield tunnel construction. Compared to traditional disturbance determination methods, this method is a more scientific and efficient approach for determining the disturbance range during shield tunnel construction. Summary of the Invention

[0005] To address the aforementioned technical shortcomings, the purpose of this invention is to provide a method for determining the disturbance range during shield tunnel construction. This method is based on displacement monitoring data from a limited number of measuring points, combined with numerical calculations, to obtain an accurate Peck settlement prediction formula and its settlement curve applicable to the geological conditions. The disturbance range during shield tunnel construction is then determined based on the modified Peck formula.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A method for determining the disturbance range during shield tunnel construction includes the following steps:

[0008] Step 1: Select the cross-section for monitoring displacement during shield tunnel construction, and set up surface settlement monitoring points and deep horizontal displacement monitoring points;

[0009] Step 2: Monitor the surface settlement and deep horizontal displacement of the soil from 50m away from the monitoring section during shield tunneling to 50m away from the monitoring section during shield tunneling; analyze and process the monitoring data to obtain the characteristics of foundation settlement and deformation under shield tunneling conditions.

[0010] 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 tunneling construction;

[0011] Step 4: Based on the surface settlement deformation and deep horizontal deformation characteristics of the soil obtained in Step 3, verify the numerical calculation model;

[0012] Step 5: Change the geological structure and soil parameters of the numerical calculation model, calculate the shield tunneling under different geological conditions and burial depth, and analyze the impact of shield tunnel construction on surface settlement.

[0013] Step 6: Fit the surface settlement data obtained from the numerical calculation to correct the Peck formula and obtain correction coefficients for different soil and rock parameters and different burial depths.

[0014] Step 7: Based on the geological conditions of the shield tunneling construction, predict the surface settlement of the shield tunnel construction according to the modified Peck formula, and determine the disturbance range of the shield tunnel construction based on the results.

[0015] Furthermore, the specific steps for setting up displacement monitoring points in step 1 are as follows: Elevation benchmarks for vertical displacement observation are set up outside the project's influence area; displacement measurement points are set up on the monitoring cross-section perpendicular to the tunnel centerline, totaling 9-15 monitoring points. The monitoring points are symmetrically arranged about the tunnel axis, with a spacing of 3-6m between the measurement points. Simultaneously, inclinometer tubes are drilled at a distance of 5-10m from the axis on the ground, and measurements are taken every 1.0m along the entire length of the guide channel from bottom to top to conduct deep horizontal displacement monitoring of the soil. The borehole depth is greater than the depth of the tunnel floor.

[0016] Furthermore, the specific steps of step 2, which involve analyzing and processing the monitoring data, are as follows: monitoring the deep horizontal displacement of the soil and the surface settlement of the tunnel boring machine as it passes through the cross section. The monitoring interval is 50 meters before and after the tunnel boring machine's excavation face from the monitoring section. The analysis yields the maximum ground settlement curve in the cross section direction and the distribution characteristics of horizontal displacement of the soil at different depths.

[0017] Furthermore, the establishment of the numerical calculation model in step 3 is specifically as follows: a three-dimensional model is constructed using numerical software, with a length greater than the length of the monitoring interval (generally 100m long) and a width greater than the total width of the measuring points on the monitoring cross section (generally 50m wide). The soil layers in the model are divided according to the results of on-site borehole logging.

[0018] Furthermore, the numerical calculation model verification in step 4 specifically involves: determining the parameters of each soil layer in the model based on the 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 points corresponding to the on-site monitoring points; verifying the accuracy of the model by comparing the numerical calculation results with the on-site monitoring results and optimizing the model mesh quality.

[0019] Furthermore, the calculation of the impact of tunnel construction on surface settlement in step 5 is as follows: In order to predict the surface settlement characteristics of shield tunnel construction under different geological conditions in this region, a large number of numerical calculations are performed on different geological structures and soil parameters and different burial depths.

[0020] Furthermore, the Peck formula modification in step 6 specifically involves: based on the calculation results of surface settlement characteristics generated under different shield tunneling conditions, fitting the surface transverse settlement trough curves under different working conditions using the least squares method, and modifying the parameters of ground loss rate and settlement trough width in the Peck formula.

[0021] Furthermore, the determination of the construction disturbance range in step 7 specifically involves: based on the geological conditions of the construction section, applying the modified Peck formula, selecting a correction coefficient corresponding to the geological conditions, and predicting the surface settlement of the shield tunnel construction; based on the predicted surface settlement curve, combined with the sensitivity of the deformation of surrounding buildings in the tunnel section and the allowable deformation value, determining the disturbance range of the shield construction.

[0022] The beneficial effects of this invention are as follows: This method uses monitoring results of ground settlement and deep soil displacement at typical cross-sections as model verification data to numerically simulate shield tunneling construction at typical cross-sections. Based on this, it leverages the advantages of numerical simulation to perform extensive numerical simulations, calculating shield tunneling conditions under different geological formations and burial depths. The traditional Peck formula is then modified based on the numerical calculation results, and the modified Peck formula is used to predict surface settlement and determine the disturbance range. This method can reduce the workload of on-site monitoring while predicting the disturbance range, making it a more scientific and efficient method for determining the disturbance range in shield tunnel construction, with significant application prospects. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a flowchart of a method for determining the disturbance range during shield tunnel construction according to the present invention;

[0025] Figure 2 This is a schematic diagram of the layout of monitoring points in a typical monitoring section of the present invention, where H is the spacing between surface settlement monitoring points; h is the spacing between the inclinometer tube and the tunnel centerline;

[0026] Figure 3 This is a numerical model diagram of shield tunnel excavation construction in an embodiment of the present invention;

[0027] Figure 4 This is a comparison chart of settlement curves between numerical simulation and on-site monitoring during shield tunnel construction, as presented in this invention.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1. Surface settlement observation point; 2. Inclined tube; 3. Tunnel floor slab; 4. Tunnel centerline. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1

[0032] like Figure 1 As shown, a method for determining the disturbance range during shield tunnel construction includes the following steps:

[0033] Step 1: Select the cross-section for monitoring displacement during shield tunnel construction, and set up surface settlement monitoring points and deep horizontal displacement monitoring points.

[0034] A monitoring section is set up perpendicular to the tunnel axis;

[0035] On the selected monitoring section, elevation benchmarks for vertical displacement observation are set up outside the scope of the project's influence.

[0036] Displacement measurement points are arranged on the monitoring cross section, with a total of 9-15 monitoring points. The monitoring points are arranged symmetrically about the tunnel axis, and the spacing between the monitoring points is 3-6m.

[0037] Boreholes are drilled at a certain distance (5-10 m) from the axis on the monitoring cross-section. Stratigraphic information, structural features, and lithological characteristics are recorded in the boreholes. The borehole depth is greater than the tunnel floor depth, and the borehole diameter is slightly larger than the outer diameter of the buried inclinometer tube. The inclinometer tube, connected to the ground, is placed into the borehole, and the gap between the inclinometer tube and the borehole is backfilled with fine sand or a mortar mixture of cement and bentonite. Measurements are taken every 1.0 m along the entire length of the guide channel from bottom to top to monitor the deep horizontal displacement of the soil.

[0038] Step 2: Monitor each measuring point on a typical cross-section during construction. The main monitoring range is from 50m from the monitoring cross-section during shield tunneling to 50m away from the monitoring cross-section during shield tunneling. Analyze and process the monitoring data to obtain the characteristics of foundation settlement and deformation under shield tunneling conditions.

[0039] Set up a sensor monitoring zone within 50m before and after the monitoring section at the tunnel face to monitor surface settlement and deep horizontal displacement. The monitoring cycle is once in the morning and once in the evening.

[0040] The collected monitoring data is processed and analyzed to obtain the cumulative settlement curves of each measuring point on the monitoring section and the maximum settlement distribution characteristics of each measuring point, and to obtain the deep horizontal displacement distribution curve of the soil.

[0041] Step 3: Taking the monitoring section as the object, establish a three-dimensional numerical calculation model, carry out numerical simulation calculation of surface deformation during shield tunneling, and obtain the stratum deformation law during shield tunneling.

[0042] A three-dimensional numerical calculation model is established based on borehole data, profile data, and geological maps of the monitoring section. The model length is greater than the length of the monitoring interval (generally 100m), the width is greater than the total width of the measuring points on the monitoring cross section (generally 50m), and the depth is greater than the depth of the inclinometer boreholes of that section. The soil layers in the model are divided based on the stratigraphic information and lithological characteristics recorded in the field boreholes.

[0043] To ensure computational accuracy, the model mesh was divided using a non-uniform mesh. A denser mesh was used in the area near the excavated tunnel, and the mesh gradually thinned out from the tunnel's central axis to both sides of the model, with a minimum of 1.0m and a maximum of 10.0m. A mesh layer was used every 1.0m in the depth direction.

[0044] Step 4: Based on the foundation settlement and deformation data of the monitoring section under shield tunneling construction conditions obtained in Step 2, verify the stratum deformation law obtained by numerical calculation in Step 3. If the calculation results are inconsistent with the measured results, optimize the model and recalculate until they match.

[0045] Based on the comprehensive analysis of the results of on-site soil layer identification, in-situ testing and geotechnical tests during the exploration, the parameters of each soil layer in the model are determined. Boundary conditions are set according to the actual construction environment and conditions, and appropriate solvers and solving algorithms are selected to run the simulation.

[0046] The nodal displacement data of each model monitoring point corresponding to the field monitoring points are extracted. The accuracy of the model is verified by comparing the numerical calculation results with the field monitoring results and optimizing the model mesh quality.

[0047] Step 5: Based on the consistency between the calculation results and the measured results, change the geological structure and soil parameters of the numerical calculation model, calculate the shield tunneling under different geological conditions and burial depths, and analyze the impact of shield tunnel construction on surface settlement.

[0048] Step 6: Fit the surface settlement data obtained from the numerical calculation to correct the Peck formula and obtain correction coefficients for different soil and rock parameters and different burial depths.

[0049] The calculation results of surface settlement characteristics under different shield tunneling conditions are analyzed. Based on the fact that the surface transverse settlement curve conforms to the Gaussian distribution, the Peck formula is used for fitting and inversion analysis. The Peck formula is modified by two important parameters of the Peck formula, namely the settlement trough width coefficient K and the soil loss rate η.

[0050] By using data from numerical simulation of surface settlement, and based on the fitting results, the correction coefficients for maximum surface settlement and settlement trough width under different working conditions are determined, and then the correction coefficients for Peck's formula under different soil and rock conditions and different burial depths are determined.

[0051] Step 7: Based on the geological conditions of the shield tunneling construction, predict the surface settlement of the shield tunnel construction according to the modified Peck formula, and determine the disturbance range of the shield tunnel construction based on the results.

[0052] Based on the geological conditions of the construction section, the modified Peck formula is applied, and a correction coefficient corresponding to the geological conditions is selected to predict the surface settlement during shield tunnel construction.

[0053] Based on the predicted surface settlement curve, and combined with the sensitivity of the surrounding buildings in the tunnel section and the allowable deformation value, the disturbance range of the shield tunneling construction is determined.

[0054] Taking the shield tunneling construction of a section of the Xuzhou Metro Line 3 Phase II project as an example, a typical cross-section of this construction section was selected as the object. The selected cross-section consists of miscellaneous fill, silt, clay, strongly weathered limestone, and moderately weathered limestone, with a tunnel depth of 11.13m. Measuring points were set up on the selected cross-section as follows: Figure 2As shown, the spacing between surface settlement measuring points is 3 m, and the distance between the inclinometer tube and the tunnel centerline is set at 5 m.

[0055] A three-dimensional numerical calculation model is constructed using the selected typical cross-section as the research object, such as... Figure 3 As shown. The model soil layers are divided based on the stratigraphic information and lithological characteristics recorded in the field boreholes. The parameters of each soil layer in the model are determined through a comprehensive analysis of the results of field soil layer identification, in-situ testing, and geotechnical testing during exploration. The numerical calculation results are compared with the field measurement results. Figure 4 As shown, the absolute error between the simulated data and the monitoring data is no greater than 2 mm, indicating good consistency. Numerical calculations show that the settlement curve caused by tunnel excavation conforms to a normal distribution curve and can be fitted using the Peck formula. Further modifications to the geological structure and soil parameters of the numerical calculation model were made to calculate the shield tunneling under different geological conditions and burial depths. The surface settlement data obtained from the numerical calculations were then fitted to correct the Peck formula, yielding correction coefficients for different soil and rock parameters and burial depths. Based on the corrected Peck formula, surface settlement during shield tunnel construction can be predicted, and the disturbance range of the shield construction can be determined based on the predicted surface settlement curve.

[0056] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for determining the disturbance range during shield tunnel construction, characterized in that, Includes the following steps: Step 1: Select the cross-section for monitoring displacement during shield tunnel construction, 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 50m away from the monitoring section during shield tunneling to 50m away from the monitoring section during shield tunneling; analyze and process the monitoring data to obtain the characteristics of foundation settlement and deformation under shield tunneling conditions. 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 tunneling construction; Step 4: Based on the surface settlement deformation and deep horizontal deformation characteristics of the soil obtained in Step 3, verify the numerical calculation model; Step 5: Change the geological structure and soil parameters of the numerical calculation model, calculate the shield tunneling under different geological conditions and burial depth, and analyze the impact of shield tunnel construction on surface settlement. Step 6: Fit the surface settlement data obtained from the numerical calculation to correct the Peck formula and obtain correction coefficients for different soil and rock parameters and different burial depths. The specific steps for correcting the Peck formula are as follows: Based on the calculation results of surface settlement characteristics under different shield tunneling conditions, fit the surface transverse settlement trough curves under different working conditions using the least squares method, and correct the parameters of stratum loss rate and settlement trough width in the Peck formula. Step 7: Based on the geological conditions of the shield tunneling construction, predict the surface settlement of the shield tunnel construction according to the modified Peck formula, and determine the disturbance range of the shield tunnel construction based on the results. Specifically, according to the geological conditions of the construction section, apply the modified Peck formula, select the correction coefficient corresponding to the geological conditions, and predict the surface settlement of the shield tunnel construction; based on the predicted surface settlement curve, combined with the sensitivity of the deformation of the surrounding buildings in the tunnel section and the allowable deformation value, determine the disturbance range of the shield tunnel construction.

2. The method for determining the disturbance range during shield tunnel construction according to claim 1, characterized in that, The specific steps for setting up displacement monitoring points in step 1 are as follows: Elevation benchmarks for vertical displacement observation are set up outside the project's influence area; displacement measurement points are set up on the monitoring cross-section perpendicular to the tunnel centerline, totaling 9-15 monitoring points. The monitoring points are symmetrically arranged about the tunnel axis, with a spacing of 3-6m between the measurement points. Simultaneously, inclinometer tubes are drilled at a distance of 5-10m from the axis on the ground, and measurements are taken every 1.0m along the entire length of the guide channel from bottom to top to conduct deep horizontal displacement monitoring of the soil. The drilling depth is greater than the depth of the tunnel floor.

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

4. The method for determining the disturbance range during 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, with a length greater than the length of the monitoring interval and a width greater than the total width of the measuring points on the monitoring cross section. The soil layers in the model are divided according to the results of on-site borehole logging.

5. The method for determining the disturbance range during shield tunnel construction according to claim 1, characterized in that, The numerical calculation model verification in step 4 specifically involves: determining the parameters of each soil layer in the model based on the 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 points corresponding to the on-site monitoring points; verifying the accuracy of the model by comparing the numerical calculation results with the on-site monitoring results and by optimizing the model mesh quality.

6. The method for determining the disturbance range during 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 as follows: In order to predict the surface settlement characteristics of shield tunnel construction under different geological conditions in this area, a large number of numerical calculations are performed on different geological structures, soil and rock parameters, and different burial depths.

Images