Prediction method of surface settlement distribution during jacking construction of bundled rectangular pipe jacking groups

Abstract

The present invention discloses a method for predicting the surface settlement distribution during the jacking construction of a bundled rectangular jacking pipe group, comprising the following steps: 1. importing the design section of the bundled structure composed of the rectangular jacking pipe group and establishing a global coordinate system; 2. formulating the jacking sequence of the rectangular jacking pipe group of the bundled structure and storing the jacking sequence in numbers; 3. establishing a local coordinate system for each rectangular jacking pipe in the bundled structure; 4. defining the soil layer distribution within the bundled structure section and assigning the internal friction angle of the soil; 5. inputting the calculation parameters of each rectangular jacking pipe; 6. calculating the surface settlement distribution of the first rectangular jacking pipe during the jacking construction; 7. starting from the second rectangular jacking pipe, iteratively calculating the surface settlement distribution of each rectangular jacking pipe during the jacking construction in the numbered order; 8. after iteratively calculating the last rectangular jacking pipe, plotting the output surface settlement distribution function Z(x) into a corresponding curve. The present invention can conveniently and efficiently predict the surface settlement during the design stage, providing a basis for the comparison and selection of pipe segment construction plans.

Description

Technical Field

[0001] The present invention relates to the technical field of computer-aided design, and in particular to a method for predicting surface settlement distribution during jacking construction of a bundled-structure rectangular jacking pipe group. Background Art

[0002] As a new type of underground excavation technology, the bundled structure uses transverse prestressed tendons to bundle the discrete, rectangular jacking pipe groups that are pushed longitudinally into an integral structure that can bear transverse forces. This solves the problem of underground excavation in water-rich soft soil areas without temporary support, soil reinforcement, full-section excavation, and the integration of advanced support and permanent structure. It has been successfully applied in underground projects with busy traffic sections, dense buildings, and shallow cover and large sections.

[0003] During the construction of bundled structures, densely packed rectangular pipe jacking inevitably disturbs the soil, causing surface subsidence, especially in shallow underground projects in water-rich soft soil. Furthermore, urban core areas have strict environmental protection requirements, further necessitating strict control of surface subsidence. Currently, existing technologies primarily focus on circular pipe jacking or single large rectangular pipe jacking. However, there are few methods or software available for calculating surface subsidence for clusters of micro-rectangular pipe jacking in bundled structures.

[0004] Therefore, how to fully consider the top pipe shape, cross-section cutting rate, pipe segment size, soil layer characteristics, spacing and disturbance, and overlapping effects to achieve convenient and efficient prediction in the design stage has become a technical problem that technical personnel in this field urgently need to solve. Summary of the Invention

[0005] In view of the above-mentioned defects of the prior art, the present invention provides a method for predicting the surface settlement distribution during the jacking construction of a bundled structure rectangular jacking pipe group. The purpose of the method is to achieve convenient and efficient prediction in the design stage, and to provide a basis for the comparison and selection of subsequent construction schemes such as pipe segment arrangement, jacking sequence, and control measures. The method is particularly suitable for calculating the surface settlement caused by the construction of ultra-close-range, small-section, rectangular jacking pipe groups in bundled structures.

[0006] To achieve the above-mentioned purpose, the present invention discloses a method for predicting the surface settlement distribution during the jacking construction of a bundled rectangular jacking pipe group. The method uses programmed software that can realize parameter input, complex equation calculation, and cyclic iteration, and performs the following steps:

[0007] Step 1: Import the design section of the bundled structure consisting of a group of rectangular jacking pipes and establish the overall coordinate system;

[0008] Step 2: Based on the imported design section of the bundled structure, a jacking sequence of the rectangular jacking pipe group of the bundled structure is formulated and numbered and stored;

[0009] Step 3: establishing a local coordinate system for each rectangular jacking tube in the bundled structure;

[0010] Step 4: defining the soil layer distribution within the cross section of the bundled structure and assigning the soil internal friction angle;

[0011] Step 5: inputting the calculation parameters of each rectangular jacking pipe;

[0012] Step 6: Calculate the surface settlement distribution of the first rectangular jacking pipe during jacking construction;

[0013] Step 7: Starting from the second rectangular jacking pipe, iteratively calculate the surface settlement distribution of each rectangular jacking pipe jacking construction in the order of the numbers;

[0014] Step 8: According to step 7, after iterative calculation to the last rectangular jacking pipe, the output surface settlement distribution function Z(x) is plotted into a corresponding curve.

[0015] Preferably, the programmed software capable of realizing parameter input, complex equation calculation, and loop iteration may be Matlab software or Python software.

[0016] Preferably, in step 1,

[0017] The horizontal axis of the overall coordinate system is x, and the vertical axis is z;

[0018] The z-axis of the global coordinate system passes through the center point of the designed cross section of the bundled structure;

[0019] The coordinate origin of the global coordinate system is the intersection of the z-axis and the ground surface line.

[0020] More preferably, in step 2, all the rectangular jacking pipes are numbered 1, 2, 3...n in sequence according to the planned jacking order of the rectangular jacking pipe group.

[0021] More preferably, in step 3,

[0022] The horizontal axis of the local coordinate system of each rectangular jacking tube is p, and the vertical axis is w;

[0023] The w axis of each local coordinate system passes through the center point of the cross section of the corresponding rectangular jacking pipe;

[0024] The coordinate origin of each local coordinate system is the intersection of the w-axis and the ground surface line.

[0025] More preferably, in step 5, the calculation parameters of each rectangular jacking pipe include the cross-sectional side length a of the rectangular jacking machine, the cross-sectional cutting rate f of the rectangular jacking machine, and the net distance Δl between the rectangular jacking pipes.

[0026] More preferably, step 6 is as follows:

[0027] Step 6.1: The calculation program calculates the horizontal distance Δx between the w axis and the z axis of the n-th rectangular top pipe according to the global coordinate system and each local coordinate system. n ;

[0028] When the w axis of each local coordinate system is located to the right of the z axis, that is, when the axis is offset, a negative sign is used to convert the global coordinate system and the corresponding local coordinate system, that is, x-Δx n ;

[0029] When the w axis of each local coordinate system is located to the left of the z axis, that is, when the axial offset is negative, the positive sign is used to convert the axis shift between the global coordinate system and the corresponding local coordinate system, that is, x+Δx n ;

[0030] Step 6.2: Calculate the vertical distance h from the cross-section center of the rectangular jacking pipe to the ground surface line based on the position of the nth rectangular jacking pipe in the global coordinate system. n ;

[0031] Step 6.3: According to the position of the nth rectangular jacking pipe in the global coordinate system and the definition of the soil layer at the location, search the database and assign the corresponding soil loss rate η of the rectangular jacking pipe jacking construction. 1,n and the corresponding correction coefficient η of the inflection point of the surface settlement curve of the rectangular jacking construction 2,n ;

[0032] Step 6.4, according to h n ,η 2,n Combined with a and f entered in step 5, the following formulas are used to calculate the cross-sectional shape correction coefficient μ1 of the rectangular pipe jacking machine, the cross-sectional cutting rate correction coefficient μ2 of the rectangular pipe jacking machine, and the horizontal distance i from the inflection point of the surface settlement curve to the center of the rectangular pipe jacking section. n ;

[0033]

[0034] Where A is the total area of ​​the rectangular top tube, and A' is the area of ​​the circular cross section with a as the diameter;

[0035] Step 6.5, the calculation program is based on the obtained η 1,n , μ1, μ2, i n , according to the following formula, calculate the maximum surface settlement W of the nth rectangular jacking pipe n,max ;

[0036]

[0037] Step 6.6, the calculation program is based on the obtained Δx n 、i n、W n,max , defined by the following formula, calculate the surface settlement distribution function Z n (x):

[0038]

[0039]

[0040] Where n represents the nth rectangular jacking pipe being calculated; x is the x-coordinate value of the surface settlement calculation point in the global coordinate system; the vertical axis z is positive to the right and negative to the left; e is the natural logarithm;

[0041] Step 6.7: Output the Δx of the nth rectangular jacking pipe obtained during the program calculation process. n , Z n (x);

[0042] Where n=1.

[0043] More preferably, step 7 is as follows:

[0044] Step 7.1: Same as step 6, calculate the Δx of the nth rectangular jacking pipe without considering the superposition, disturbance and mutual influence of the rectangular jacking pipe groups constructed successively. n 、h n 、i n , Z n (x);

[0045] Step 7.2: Import the Δx calculated and output in the previous step n-1 ;

[0046] Step 7.3: Assign a vertical disturbance factor β based on the position of the nth rectangular jacking pipe in the global coordinate system and the soil characteristics at the location. v,n , when there is no obstruction on the top, it is 1; when there is obstruction on the top, the value depends on the soil layer;

[0047] Step 7.4: The calculation program calculates the horizontal disturbance factor β according to the position of the nth rectangular jacking pipe in the global coordinate system, the soil characteristics at its location, and the horizontal distance from the previous (n-1)th rectangular jacking pipe using the following formula: h,n :

[0048]

[0049] Where ξ is the influencing parameter of the jacking pipe spacing; in the formula, the nth and the preceding n-1th rectangular jacking pipes are positive when they are located on both sides of the vertical axis z of the overall coordinate system of the bundled structure, and negative when they are on the same side; is the internal friction angle of the soil;

[0050] Step 7.5: According to the obtained βv,n , β h,n , Δx n-1 、i n , combined with a and Δl input in step 5, the construction influence function r of the bundled structure jacking group is calculated according to the following formula: n-1 (x) represents the disturbance and support effect caused by the jacking of the previous (n-1) rectangular jacking pipe when the nth rectangular jacking pipe is jacked:

[0051]

[0052] Step 7.6, according to the obtained r n-1 (x), Z n (x), calculate the surface settlement distribution function Z(x) according to the following formula;

[0053] Z(x)=Z1(x)+r1(x)Z2(x)+r2(x)Z3(x)+...+r n-1 (x)Z n (x);

[0054] Step 7.7, the obtained Δx of the nth rectangular top pipe n , Z(x).

[0055] More preferably, the η 1,n ,η 2,n , β v,n The database, combined with soil layer characteristics, takes the following values:

[0056] The soil type is silt or silty soil, η 1,n is 1.5%, η 2,n is 1.30, β v,n is 0.7;

[0057] The soil type is fill, η 1,n is 2.0%, η 2,n is 1.20, β v,n is 0.6;

[0058] The soil type is clay soil with a liquid index ≥ 0.8, η 1,n is 0.7%, η 2,n is 1.30, β v,n is 0.25;

[0059] The soil type is large-scale compacted fill, and the soil is silt with a compaction coefficient greater than 0.95 and a clay content ≥10%. 1,n is 0.8%, η 2,n is 1.15, β v,n is 0.4;

[0060] The soil type is large-scale compacted fill, and the dry density is ≥20kg / m3 graded sand and gravel, η 1,n is 0.5%, η 2,n is 1.00, β v,n is 0.15;

[0061] The soil type is silt, and the clay content is ≥10%, η 1,n is 0.6%, η 2,n is 1.10, β v,n is 0.3;

[0062] The soil type is silt, and the clay content is less than 10%, η 1,n is 0.7%, η 2,n is 1.05, β v,n is 0.2;

[0063] The soil type is clay soil with liquid index < 0.8, β 1,n is 0.8%, η 2,n is 1.20, β v,n is 0.6;

[0064] The soil type is silt sand or fine sand, η 1,n is 0.6%, η 2,n is 1.00, β v,n is 0.15;

[0065] The soil type is medium, coarse sand, gravel sand or crushed stone soil, η 1,n is 0.5%, η 2,n is 1.00, β v,n is 0.15.

[0066] Beneficial effects of the present invention:

[0067] The present invention can achieve convenient and efficient prediction in the design stage of the bundled structure, and provide a basis for the comparison and selection of subsequent construction plans such as pipe segment arrangement, jacking sequence, and control measures.

[0068] The present invention is particularly suitable for the construction of ultra-close-range, micro-section, rectangular jacking pipe groups in bundled structures, and for calculating surface settlement that takes into account the effects of jacking pipe shape, section cutting rate, pipe segment size, soil layer characteristics, spacing and disturbance, and overlap.

[0069] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 The cross section and overall coordinate system of the bundled structure design in one embodiment of the present invention are shown.

[0071] Figure 2 A simplified calculation diagram and a local coordinate system for the first pipe jacking in one embodiment of the present invention are shown.

[0072] Figure 3 A simplified diagram of the superposition calculation of the first and second jacking pipes and a local coordinate system are shown in one embodiment of the present invention.

[0073] Figure 4 A simplified diagram of the superposition calculation of the first, second and third jacking pipes and a local coordinate system are shown in one embodiment of the present invention.

[0074] Figure 5 A simplified diagram of top pipe stacking calculation in one embodiment of the present invention is shown.

[0075] Figure 6 Shows the measured data and calculated results of surface settlement after all pipe jacking in one embodiment of the present invention. DETAILED DESCRIPTION

[0076] Example

[0077] Taking the bundled structure of an underground pedestrian passage project as an example, the surface settlement distribution prediction method for the jacking construction of a bundled rectangular pipe group is explained:

[0078] The bundled structure of this embodiment includes a total of 21 jacking pipes that are pushed in successively. Among them, the first jacking pipe is the test pipe S0, and the rest are standard pipes. The order of on-site jacking construction is: 1) After the first S0 is pushed in first, the 7 standard pipes above S0 are pushed in sequence to serve as the top of the bundled structure; 2) 6 standard pipes on both sides of S0 are pushed in, 3 on each side, to serve as the sides of the bundled structure; 3) 7 standard pipes below S0 are pushed in to serve as the bottom of the bundled structure to complete the closure. The top of the formed bundled structure is covered with 3m of soil, with a height of 5.4m and a span of 7.6m; the cross-sectional size of the jacking pipe is 1.0m, and the distance between each two jacking pipes is 100mm; the jacking construction adopts a planetary single-disc rectangular jacking machine, and the cross-sectional cutting rate of the jacking machine is 0.975.

[0079] Use Matlab, Python, or other programming software that can implement parameter input, complex equation calculation, and loop iteration to write code and execute the following steps:

[0080] Step 1: Import the design section of the bundled structure and establish the overall coordinate system;

[0081] Import the design section of the bundled structure of the embodiment and establish the overall coordinate system with the horizontal axis x and the vertical axis z; the z axis passes through the center point of the design section; the coordinate origin is the intersection of the z axis and the surface line, see the attached Figure 1 .

[0082] Step 2: Based on the imported bundled structure design section, a jacking sequence of the bundled structure rectangular jacking pipe group is formulated and numbered and stored;

[0083] According to the on-site jacking sequence, each rectangular jacking pipe is numbered n=1, 2, 3...21, see attached. Figure 1 .

[0084] Step 3: Establish a local coordinate system for each rectangular jacking pipe in the bundled structure;

[0085] The horizontal axis of the local coordinate system of each rectangular jacking pipe is p, and the vertical axis is w; the w axis passes through the cross-section center point of the calculated single rectangular jacking pipe; the coordinate origin is the intersection of the w axis and the ground surface line.

[0086] Step 4: Define the soil layer distribution within the cross section of the bundled structure and assign the internal friction angle of the soil;

[0087] The soil layer where each jacking pipe of the bundled structure is located is clay with a liquid index of ≥ 0.8, and the internal friction angle of the soil layer is

[0088] Step 5: Input the relevant calculation parameters of the rectangular jacking pipe;

[0089] The cross-section side length of the rectangular pipe jacking machine is a=1;

[0090] The cross-section cutting rate of the rectangular pipe jacking machine is f = 0.975;

[0091] The net distance between rectangular top pipes is Δl=0.1.

[0092] Step 6: Calculate the surface settlement distribution of the first (n=1) rectangular pipe jacking construction;

[0093] Step 6.1: The first (n=1) rectangular jacking pipe is the test pipe. The calculation diagram and local coordinate system are shown in the attached Figure 2 , the global coordinate system xz is the same as the local coordinate system pw of the rectangular jacking tube;

[0094] The calculation program automatically calculates the horizontal distance Δx1=0 between the vertical axis w of the local coordinate system of the rectangular jacking pipe and the vertical axis z of the global coordinate system;

[0095] Step 6.2: The calculation program automatically calculates the vertical distance h1=6.1 from the cross-section center of the rectangular jacking pipe to the ground surface based on the position of the rectangular jacking pipe in the global coordinate system.

[0096] Step 6.3: The calculation program searches the database and automatically assigns the soil loss rate η of the rectangular pipe jacking construction based on the fact that the soil layer where the rectangular pipe is located is clay with a liquid index ≥ 0.8. 1,1 =0.07 and the correction coefficient η of the inflection point of the surface settlement curve for rectangular pipe jacking construction2,1 =1.3;

[0097] Step 6.4, calculation program based on the obtained h1, η 2,1 , combined with a and f entered in step 5, automatically calculate according to the following formula:

[0098] Cross-sectional shape correction factor of rectangular pipe jacking machine Correction coefficient of cross-section cutting rate of rectangular pipe jacking machine The horizontal distance from the inflection point of the surface settlement curve to the center of the rectangular jacking pipe section

[0099] Step 6.5, the calculation program is based on the obtained η 1,1 , μ1, μ2, i1, defined by the following formula, automatically calculate the maximum surface settlement W of the rectangular jacking pipe 1,max ;

[0100]

[0101] Step 6.6, the calculation program is based on the obtained Δx1, i1, W 1,max , defined by the following formula, the surface settlement distribution function Z1(x) during the construction of a single rectangular jacking pipe is automatically calculated:

[0102]

[0103] Step 6.7: Output the Δx of the first rectangular jacking pipe obtained during the program calculation process. n , Z n (x).

[0104] Step 7: Starting from the second pipe (n=2), iteratively calculate the surface settlement distribution of the rectangular pipe jacking construction in the order of the numbers;

[0105] The calculation diagram and local coordinate system of the second (n=2) rectangular jacking pipe are shown in the attached Figure 3 , the global coordinate system xz is the same as the local coordinate system pw of the rectangular jacking tube;

[0106] Step 7.1: Same as step 6. Without considering the overlapping, disturbance, and mutual influence of supports during the sequential construction of the bundled rectangular jacking pipe group, automatically calculate the second rectangular jacking pipe:

[0107] Δx2=0, h2=3.5, i2=0.5×1.3×3.5=2.275,

[0108]

[0109] Step 7.2: Import Δx1=0 calculated and output in the previous step;

[0110] Step 7.3: No vertical support influence, the calculation program automatically assigns the vertical disturbance factor β v,2 =1;

[0111] Step 7.4: There is no disturbance effect in the horizontal direction, and the calculation program automatically assigns the horizontal disturbance factor β h,2 =0:

[0112] Step 7.5, the calculation program is based on the obtained β v,2 , β h,2 , Δx1, i2, combined with a and Δl input in step 5, automatically calculate the construction influence function of the bundled structure jacking group:

[0113]

[0114] Step 7.6: The calculation program automatically calculates the surface settlement distribution function Z(x) after the second rectangular jacking pipe is inserted based on the obtained r1(x) and Z2(x).

[0115]

[0116] Step 7.7. Output Δx2 and Z(x) of the second rectangular top pipe obtained during the program calculation process.

[0117] Iterate the third (n=3) rectangular jacking pipe, calculation diagram and local coordinate system, see attached Figure 4 , the local coordinate system pw of the rectangular jacking tube has a positive axial horizontal offset relative to the global coordinate system xz;

[0118] Step 7.1: Same as step 6. Without considering the overlapping, disturbance, and mutual influence of supports during the sequential construction of the bundled rectangular jacking pipe group, automatically calculate the third rectangular jacking pipe:

[0119] Δx3=a+Δl=1.1, h3=3.5, i3=0.5×1.3×3.5=2.275,

[0120]

[0121] The positive axis is horizontally offset, and after the axis shift conversion of x-Δx3=x-1.1,

[0122]

[0123] Step 7.2: Import Δx2=0 calculated and output in the previous step;

[0124] Step 7.3: No vertical support influence, the calculation program automatically assigns the vertical disturbance factor β v,3 =1;

[0125] Step 7.4: Calculation program automatically calculates Combined soil internal friction angle According to the following formula

[0126]

[0127] Automatically calculate and assign

[0128] Step 7.5, the calculation program is based on the obtained β v,3 , β h,3 , Δx2, i3, combined with a and Δl input in step 5, automatically calculate the construction influence function of the bundled structure jacking group:

[0129]

[0130] Step 7.6: The calculation program automatically calculates the surface settlement distribution function Z(x) after the third rectangular jacking pipe is completed based on the obtained r2(x) and Z3(x).

[0131]

[0132] Step 7.7. Output Δx3 and Z(x) of the third rectangular jacking pipe obtained during the program calculation process.

[0133] By analogy, when iterating the fourth (n=4) rectangular jacking pipe, the local coordinate system pw has a positive axial horizontal offset relative to the global coordinate system xz;

[0134] Step 7.1: Same as step 6, automatically calculate the fourth rectangular jacking pipe:

[0135] Δx4=2×(a+Δl)=2.2, h4=3.5, i4=0.5×1.3×3.5=2.275,

[0136]

[0137] The positive axis is horizontally offset, and after the axis shift conversion of x-Δx4=x-2.2,

[0138]

[0139] Step 7.2, import Δx3=1.1 calculated and output in the previous step;

[0140] Step 7.3: No vertical support influence, the calculation program automatically assigns the vertical disturbance factor β v,4 =1;

[0141] Step 7.4: Calculation program automatically calculates Combined soil internal friction angle According to the following formula

[0142]

[0143] Automatically calculate and assign

[0144] Step 7.5, the calculation program is based on the obtained β v,4 , β h,4 , Δx3, i4, combined with a and Δl input in step 5, automatically calculate the construction influence function of the bundled structure jacking group:

[0145]

[0146] Step 7.6: The calculation program automatically calculates the surface settlement distribution function Z(x) after the fourth rectangular jacking pipe is installed based on the obtained r3(x) and Z4(x).

[0147]

[0148] Step 7.7. Output Δx4 and Z(x) of the third rectangular top pipe obtained during the program calculation process.

[0149] By analogy, when iterating the fifth (n=5) rectangular jacking pipe, the local coordinate system pw has a negative axial horizontal offset relative to the global coordinate system xz;

[0150] Step 7.1: Same as step 6, automatically calculate the third rectangular jacking pipe:

[0151] Δx5=a+Δl=1.1, h5=3.5, i5=0.5×1.3×3.5=2.275,

[0152]

[0153] Negative axial horizontal offset, after the axis shift conversion of x+Δx5=x+1.1,

[0154]

[0155] Step 7.2, import Δx4=2.2 calculated and output in the previous step;

[0156] Step 7.3: No vertical support influence, the calculation program automatically assigns the vertical disturbance factor β v,4 =1;

[0157] Step 7.4: Calculation program automatically calculates According to the following formula

[0158]

[0159] Automatically calculate and assign β h,5 =0.1:

[0160] Step 7.5, the calculation program is based on the obtained β v,5 , β h,5 , Δx4, i5, combined with a and Δl input in step 5, automatically calculate the construction influence function of the bundled structure jacking group:

[0161]

[0162] Step 7.6: The calculation program automatically calculates the surface settlement distribution function Z(x) after the fifth rectangular jacking pipe is jacked, considering the mutual influence, based on the obtained r4(x) and Z5(x).

[0163]

[0164] Step 7.7. Output Δx5 and Z(x) of the third rectangular jacking pipe obtained during the program calculation process.

[0165] Similarly, calculate the surface settlement after all the top pipes are completed. The calculation diagram is attached. Figure 5 .

[0166] The construction condition corresponding to the side and bottom pipe groups is "up first, then down". The calculation process is the same. It is only necessary to search the following database according to the characteristics of the local stratum and consider the vertical disturbance factor β of the support effect. v,n =1.

[0167] The η 1,n ,η 2,n , β v,n The database, combined with soil layer characteristics, takes the following values:

[0168] The soil type is silt or silty soil, η 1,n is 1.5%, η 2,n is 1.30, β v,n is 0.7;

[0169] The soil type is fill, η 1,n is 2.0%, η 2,n is 1.20, β v,n is 0.6;

[0170] The soil type is clay soil with a liquid index ≥ 0.8, η 1,n is 0.7%, η 2,n is 1.30, β v,n is 0.25;

[0171] The soil type is large-scale compacted fill, and the soil is silt with a compaction coefficient greater than 0.95 and a clay content ≥10%. 1,nis 0.8%, η 2,n is 1.15, β v,n is 0.4;

[0172] The soil type is large-scale compacted fill, and the dry density is ≥20kg / m3 graded sand and gravel, η 1,n is 0.5%, η 2,n is 1.00, β v,n is 0.15;

[0173] The soil type is silt, and the clay content is ≥10%, η 1,n is 0.6%, η 2,n is 1.10, β v,n is 0.3;

[0174] The soil type is silt, and the clay content is less than 10%, η 1,n is 0.7%, η 2,n is 1.05, β v,n is 0.2;

[0175] The soil type is clay soil with a liquid index of less than 0.8, η 1,n is 0.8%, η 2,n is 1.20, β v,n is 0.6;

[0176] The soil type is silt sand or fine sand, η 1,n is 0.6%, η 2,n is 1.00, β v,n is 0.15;

[0177] The soil type is medium, coarse sand, gravel sand or crushed stone soil, η 1,n is 0.5%, η 2,n is 1.00, β v,n is 0.15.

[0178] Step 8. According to step 7, after iterative calculation to the last rectangular jacking pipe, the output Z(x) is plotted into a corresponding curve.

[0179] After iterative calculation to the last rectangular jacking pipe, the measured data of surface settlement and the calculated results are shown in the attached Figure 6 It can be seen that due to the mutual influence of the jacking pipe group, the settlement trough has a significant offset phenomenon. The calculation method and programmed implementation proposed in this invention can take into account the jacking pipe shape, size, cross-section cutting rate, soil layer characteristics, spacing and disturbance, and overlap effects. It is particularly suitable for calculating surface settlement caused by the construction of bundled structure ultra-close-range, micro-section, and rectangular jacking pipe groups.

[0180] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A method for predicting surface settlement distribution during jacking construction of a bundled rectangular pipe jacking group; characterized by: Using programmed software that can implement parameter input, complex equation calculation, and loop iteration, perform the following steps: Step 1: Import the design section of the bundled structure consisting of a group of rectangular jacking pipes and establish the overall coordinate system; The horizontal axis of the overall coordinate system is x, and the vertical axis is z; The z-axis of the global coordinate system passes through the center point of the designed cross section of the bundled structure; The origin of the global coordinate system is the intersection of the z-axis and the ground surface line; Step 2: Based on the imported design section of the bundled structure, a jacking sequence of the rectangular jacking pipe group of the bundled structure is formulated and numbered and stored; all the rectangular jacking pipes are numbered 1, 2, 3, ..., n in sequence according to the formulated jacking sequence of the rectangular jacking pipe group; Step 3: establishing a local coordinate system for each rectangular jacking tube in the bundled structure; The horizontal axis of the local coordinate system of each rectangular jacking tube is p, and the vertical axis is w; The w axis of each local coordinate system passes through the center point of the cross section of the corresponding rectangular jacking pipe; The origin of each local coordinate system is the intersection of the w axis and the ground surface line; Step 4: defining the soil layer distribution within the cross section of the bundled structure and assigning the soil internal friction angle; Step 5: inputting the calculation parameters of each rectangular jacking pipe; The calculation parameters of each rectangular jacking pipe include the cross-sectional side length a of the rectangular jacking machine, the cross-sectional cutting rate f of the rectangular jacking machine, and the net distance Δl between the rectangular jacking pipes; Step 6: Calculate the surface settlement distribution of the first rectangular jacking pipe during jacking construction. Step 6 is as follows: Step 6.1: The calculation program calculates the horizontal distance Δx between the w axis and the z axis of the n-th rectangular top pipe according to the global coordinate system and each local coordinate system. n ; When the w axis of each local coordinate system is located to the right of the z axis, that is, when the axis is offset, a negative sign is used to convert the global coordinate system and the corresponding local coordinate system, that is, x-Δx n ; When the w axis of each local coordinate system is located to the left of the z axis, that is, when the axial offset is negative, the positive sign is used to convert the axis shift between the global coordinate system and the corresponding local coordinate system, that is, x+Δx n ; Step 6.2: Calculate the vertical distance h from the cross-section center of the rectangular jacking pipe to the ground surface line based on the position of the nth rectangular jacking pipe in the global coordinate system. n ; Step 6.3: According to the position of the nth rectangular jacking pipe in the global coordinate system and the definition of the soil layer at the location, search the database and assign the corresponding soil loss rate η of the rectangular jacking pipe jacking construction. 1,n and the corresponding correction coefficient η of the inflection point of the surface settlement curve of the rectangular jacking construction 2,n ; Step 6.4, according to h n ,η 2,n Combined with a and f entered in step 5, the following formulas are used to calculate the cross-sectional shape correction coefficient μ1 of the rectangular pipe jacking machine, the cross-sectional cutting rate correction coefficient μ2 of the rectangular pipe jacking machine, and the horizontal distance i from the inflection point of the surface settlement curve to the center of the rectangular pipe jacking section. n ; Where A is the total area of ​​the rectangular top tube, and A' is the area of ​​the circular cross section with a as the diameter; Step 6.5, the calculation program is based on the obtained η 1,n , μ1, μ2, i n , according to the following formula, calculate the maximum surface settlement W of the nth rectangular jacking pipe n,max ; Step 6.6, the calculation program is based on the obtained Δx n 、i n 、W n,max , defined by the following formula, calculate the surface settlement distribution function Z n (x): Where n represents the nth rectangular jacking pipe being calculated; x is the x-axis coordinate value of the surface settlement calculation point in the global coordinate system; the vertical axis z is positive to the right and negative to the left; e is the natural logarithm; Step 6.7: Output the Δx of the nth rectangular jacking pipe obtained during the program calculation process. n 、Z n (x); Where n = 1; Step 7: Starting from the second rectangular jacking pipe, iteratively calculate the surface settlement distribution of each rectangular jacking pipe jacking construction in the order of the numbers; Step 8: According to step 7, after iterative calculation to the last rectangular jacking pipe, the output surface settlement distribution function Z(x) is plotted into a corresponding curve.

2. The surface settlement distribution prediction method for jacking construction of a bundled rectangular jacking pipe group according to claim 1 is characterized in that: The programmed software capable of realizing parameter input, complex equation calculation, and loop iteration is Matlab software and Python software.

3. The surface settlement distribution prediction method for jacking construction of a bundled rectangular jacking pipe group according to claim 1 is characterized in that: Step 7 is as follows: Step 7.1: Same as step 6, calculate the Δx of the nth rectangular jacking pipe without considering the superposition, disturbance and mutual influence of the rectangular jacking pipe groups constructed successively. n 、h n 、i n 、Z n (x); Step 7.2: Import the Δx calculated and output in the previous step n-1 ; Step 7.3: Assign a vertical disturbance factor β based on the position of the nth rectangular jacking pipe in the global coordinate system and the soil characteristics at the location. v,n , when there is no obstruction on the top, it is 1; when there is obstruction on the top, the value depends on the soil layer; Step 7.4: The calculation program calculates the horizontal disturbance factor β according to the position of the nth rectangular jacking pipe in the global coordinate system, the soil characteristics at its location, and the horizontal distance from the previous (n-1)th rectangular jacking pipe using the following formula: h,n : Where ξ is the influencing parameter of the jacking pipe spacing; in the formula, the nth and the preceding n-1th rectangular jacking pipes are positive when they are located on both sides of the vertical axis z of the overall coordinate system of the bundled structure, and negative when they are on the same side; is the internal friction angle of the soil; Step 7.5: According to the obtained β v,n , β h,n , Δx n-1 、i n , combined with a and Δl input in step 5, the construction influence function r of the bundled structure jacking group is calculated according to the following formula: n-1 (x) represents the disturbance and support effect caused by the jacking of the previous (n-1) rectangular jacking pipe when the nth rectangular jacking pipe is jacked: Step 7.6, according to the obtained r n-1 (x), Z n (x), calculate the surface settlement distribution function Z(x) according to the following formula; Z(x)=Z1(x)+r1(x)Z2(x)+r2(x)Z3(x)+…+r n-1 (x)Z n (x); Step 7.7, the obtained Δx of the nth rectangular top pipe n , Z(x).

4. The surface settlement distribution prediction method for jacking construction of a bundled rectangular jacking pipe group according to claim 3 is characterized in that: The η 1,n ,η 2,n , β v,n The database, combined with soil layer characteristics, takes the following values: The soil type is silt or silty soil, η 1,n is 1.5%, η 2,n is 1.30, β v,n is 0.7; The soil type is fill, η 1,n is 2.0%, η 2,n is 1.20, β v,n is 0.6; The soil type is clay soil with a liquid index ≥ 0.8, η 1,n is 0.7%, η 2,n is 1.30, β v,n is 0.25; The soil type is large-scale compacted fill, and the soil is silt with a compaction coefficient greater than 0.95 and a clay content ≥10%. 1,n is 0.8%, η 2,n is 1.15, β v,n is 0.4; The soil type is large-scale compacted fill, and the dry density is ≥20kg / m3 graded sand and gravel, η 1,n is 0.5%, η 2,n is 1.00, β v,n is 0.15; The soil type is silt, and the clay content is ≥10%, η 1,n is 0.6%, η 2,n is 1.10, β v,n is 0.3; The soil type is silt, and the clay content is less than 10%, η 1,n is 0.7%, η 2,n is 1.05, β v,n is 0.2; The soil type is clay soil with liquid index < 0.8, β 1,n is 0.8%, η 2,n is 1.20, β v,n is 0.6; The soil type is silt sand or fine sand, η 1,n is 0.6%, η 2,n is 1.00, β v,n is 0.15; The soil type is medium, coarse sand, gravel sand or crushed stone soil, η 1,n is 0.5%, η 2,n is 1.00, β v,n is 0.15.

Images