A method for designing jacking sequence of multi-wire parallel pipeline construction

Abstract

The application discloses a kind of multi-line parallel pipeline jacking reasonable construction sequence design methods, using numerical calculation means, respectively calculate the stability safety factor K of different pipeline cover layer thickness H, different interlayer width D etc. ij Between different pipeline jacking sequence of the i-th working condition, compare the stability safety factor K of pipeline cavern ij Size, sequentially select the minimum value K ijmin Of each pipeline safety factor under the i-th working condition, compare the K ijmin Value size under different working conditions and select the maximum max [K ijmin ], the pipeline construction cavern max [K ijmin ] corresponding working condition under the pipeline construction jacking sequence of multi-line parallel pipeline is optimal jacking sequence.The application uses finite element strength reduction method to obtain the stability safety factor K of pipeline cavern, compares the stability safety factor K of cavern under different jacking sequence of working condition, and the pipeline construction jacking sequence with maximum safety factor is taken as the reasonable jacking sequence of pipeline construction under the working condition.

Description

Technical Field

[0001] This invention relates to the field of underground pipeline jacking technology, specifically a method for designing the jacking sequence in multi-line parallel pipeline construction. Background Technology

[0002] With the rapid development of urban construction in my country, surface space can no longer meet the needs of urban infrastructure construction, and the development and utilization of underground space is receiving increasing attention. Pipe jacking, as a trenchless construction technology, is increasingly widely used in urban infrastructure construction due to its advantages such as minimal impact on the surrounding environment, safety, speed, and efficiency. However, the characteristics of multi-line pipe jacking construction inevitably lead to disturbance during construction, causing deformation of the surrounding soil. Excessive deformation may harm surrounding waterways and other structures. Furthermore, the construction of multiple pipelines also involves mutual influence, making the stress redistribution of the surrounding strata more complex. To ensure the safety of construction under rivers, it is essential to rationally and scientifically determine the construction sequence of multi-line pipe jacking, thereby reducing the potential dangers of multi-line pipe jacking construction.

[0003] Currently, research on the construction of shallow-buried, large-diameter pipelines with thin overburden and small clearances under rivers mainly focuses on reinforcing weak riverbeds or studying the jacking parameters of individual pipe jacking operations, without addressing the issue of a reasonable construction sequence for multiple pipelines. However, multi-pipeline construction is increasingly common in practical projects, and an unreasonable construction sequence for multiple pipelines can easily jeopardize pipeline construction safety. Blindly following the construction experience of a single pipeline ignores the mutual constraints between multiple pipelines, which is an unreasonable and unscientific construction method. Therefore, it is necessary to propose a reasonable construction sequence that scientifically guides actual construction sites, taking into account the cross-sectional spatial distribution of multiple pipelines, thereby ensuring the safe construction of multi-pipeline pipelines under rivers. Summary of the Invention

[0004] The purpose of this invention is to provide a method for designing the jacking sequence of multi-line parallel pipeline construction. This method allows for the selection of the pipeline jacking sequence with the highest safety factor for pipeline tunnel stability from multiple jacking sequence types, based on different working conditions, in order to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for designing the jacking sequence in multi-line parallel pipeline construction, the method comprising the following steps:

[0006] S1. Obtain the basic parameters of the multi-line parallel pipeline and the basic parameters of the strata where the pipeline is located. The basic parameters of the multi-line parallel pipeline include the number of pipelines n, the thickness of the overburden layer H, the diameter of the pipeline d, the width of the interlayer between pipelines D, and the external load q. The basic parameters of the strata where the pipeline is located include the elastic modulus E, Poisson's ratio μ, the specific weight γ, the cohesion c, and the internal friction angle.

[0007] S2. Establish a numerical model of the stratigraphic structure with stress and deformation characteristics around the multi-line parallel pipe jacking;

[0008] S3. Based on the parameters obtained in S1 and the numerical model analysis of the stress and deformation characteristics of the surrounding strata in S2, the stress state of the surrounding strata at any point after the pipeline excavation can be obtained, and the vertical displacement deformation value S1 at the pipeline arch can be recorded.

[0009] S4. Combine cohesion c and internal friction angle After reduction, the reduced parameters are re-input into the numerical model for recalculation, and the vertical displacement deformation value S2 at the pipe arch is recorded. The reduction formula is as follows:

[0010]

[0011]

[0012] Where c′ is the reduced cohesion. The angle of internal friction is the reduced angle, and k′ is the reduction factor;

[0013] S5. Combine cohesion c and internal friction angle The reduction is performed continuously according to the reduction formula in S4, and the reduced parameters are re-input into the numerical model for recalculation until the calculation fails to converge, indicating that the pipeline has failed. During the calculation process, the vertical displacement deformation value at the pipeline arch after each reduction calculation is recorded sequentially and denoted as {S3, S4, S5, ... S... n};

[0014] S6. Calculate the safety factor K for the stability of the pipeline cavern based on the obtained vertical displacement deformation value S at the top of the pipeline arch and the reduction factor k′.

[0015] S7. Based on the number of pipelines n, determine m different excavation sequences for multi-line parallel pipe jacking, and calculate the safety factor K for pipeline tunnel stability under each of the m different excavation sequences. ij Where i takes the values ​​1, 2, 3, 4, ... m, and j takes the values ​​1, 2, 3, ... n;

[0016] S8. Compare the safety factor K for pipeline tunnel stability among different pipeline jacking sequences under the i-th working condition. ijThe size of the safety factor K is selected sequentially for each pipeline under the i-th working condition, using the minimum value K. ijmin ;

[0017] S9. Compare m K under m different working conditions. ijmin Size, select the minimum safety factor K under m working conditions ijmin The maximum value of max[K ijmin The safe pipeline excavation sequence corresponding to this safety factor under the working conditions is the determined optimal jacking sequence method for multi-line parallel pipeline construction.

[0018] Compared with existing technologies, this invention uses the finite element strength reduction method to obtain the safety factor of pipeline tunnel stability, compares the size of the safety factor of tunnel stability under different jacking sequences under different working conditions, and takes the pipeline construction jacking sequence with the maximum safety factor as the reasonable jacking sequence for pipeline construction under that working condition. It proposes a method that can scientifically guide the construction sequence on the actual construction site, thereby ensuring the safe construction of multi-line pipelines crossing rivers and reducing the probability of safety accidents during construction. Attached Figure Description

[0019] Figure 1 This is a flowchart of the jacking sequence design method for multi-line parallel pipeline construction in this invention;

[0020] Figure 2 This is a schematic diagram of the different pipe jacking sequences when n is 3 in an embodiment of the present invention. Detailed Implementation

[0021] 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.

[0022] The finite element strength reduction method essentially involves continuously reducing the strength parameters of the soil and rock material under a certain external load until the strata around the pipeline reach a limit state, thereby revealing the failure surface and obtaining the safety factor k. When k>1, it indicates no failure; k<1, it indicates failure; and k=1, it indicates a critical state.

[0023] This invention provides a method for designing the jacking sequence in multi-line parallel pipeline construction, comprising the following steps:

[0024] S1. Obtain the basic parameters of the multi-line parallel pipeline and the basic parameters of the strata where the pipeline is located. The basic parameters of the multi-line parallel pipeline include the number of pipelines n, the thickness of the overburden layer H, the diameter of the pipeline d, the width of the interlayer between pipelines D, and the external load q. The basic parameters of the strata where the pipeline is located include the elastic modulus E, Poisson's ratio μ, the specific weight γ, the cohesion c, and the internal friction angle.

[0025] The basic geological parameters of the strata where the pipeline is located are used to calculate the minimum pipeline overburden thickness H. min Minimum pipe gap width D min The specific calculation method will be described below; the basic parameters of the multi-line parallel pipe are used in the numerical calculation software described below. Specifically, the basic pipe parameters need to be set during the modeling process in this software in order to build a suitable model. In this embodiment, the Midas GTS NX numerical analysis software is used.

[0026] S2. Establish a numerical model of the stress and deformation characteristics of the strata surrounding the multi-line parallel pipe jacking project, including the following steps:

[0027] Step 1: Establish the geometric model of the pipe jacking and soil: In the numerical analysis software, obtain the data in S1 to establish a multi-line parallel pipe jacking and stratum geometric model;

[0028] Step 2: Input formation parameters and set material parameter properties in numerical analysis software: When establishing the soil and pipeline calculation model, select the appropriate element type and assign the corresponding parameters;

[0029] Step 3: Mesh generation and structural unit creation: The established geometric model is meshed using the built-in automatic hybrid mesh generation function of the numerical analysis software. The mesh size increases radially from the center of the jacking pipe.

[0030] Step 4: Set loads and boundary conditions: Use the automatic boundary conditions provided by the numerical analysis software program.

[0031] Step 5: Define the construction stages: The construction stages are divided into the initial stress stage and each pipe excavation stage. In the numerical analysis software, "passivate data" is used to simulate soil excavation within the pipe, and "activate data" is used to simulate the jacking of the pipe structure. It is important to note that before simulating the step-by-step jacking, the displacement generated by the initial stress field should be reset to zero.

[0032] Step 6: Add working condition analysis: Add an analysis case and select an appropriate analysis type. For the multi-line parallel pipe jacking construction process, the analysis type can be selected as "Construction Stage", and "Stress Analysis Initial Stage" can be checked in the "Analysis Control" option;

[0033] Step 7: Analyze and solve;

[0034] Step 8: Post-processing and result analysis.

[0035] S3. Based on the parameters obtained in S1 and the numerical model analysis of the stress deformation characteristics of the surrounding strata in S2, the stress state of the surrounding strata at any point after the pipeline excavation can be obtained, and the vertical displacement deformation value at the pipeline arch is recorded as S1.

[0036] S4. Combine cohesion c and internal friction angle After reduction, the reduced parameters are re-inputted into the model and recalculated. During the calculation, the vertical displacement deformation value at the pipe arch is recorded and denoted as S2. The reduction formula is as follows:

[0037]

[0038]

[0039] Where c′ is the reduced cohesion. is the reduced internal friction angle, and k′ is the reduction coefficient.

[0040] S5. Combine cohesion c and internal friction angle The parameters are continuously reduced according to the formula in S4, and the reduced parameters are re-inputted into the model for recalculation until the calculation fails to converge, indicating that the pipeline has failed. During the calculation process, the vertical displacement deformation value at the pipeline arch after each reduction calculation is continuously recorded and denoted as {S3, S4, S5, ... S... n};

[0041] S6. Calculate the safety factor K for the stability of the pipeline tunnel based on the obtained vertical displacement deformation value S at the pipeline arch and the reduction factor k′. This includes the following steps:

[0042] Step 1: Plot the Sk′ curve based on the relevant data of the vertical displacement deformation value s at the top of the pipe obtained from the numerical analysis model and the reduction coefficient k′;

[0043] Step 2: Perform a fourth-order polynomial fitting on the vertical displacement deformation value S of the surrounding strata crown and the multiple reduction coefficients k′ to obtain the fitting equation:

[0044] S=a0+a1k′+a2k′ 2 +a3k′ 3 +a4k′ 4

[0045] In the formula, a0 to a4 are undetermined coefficients;

[0046] Step 3: Standardize the fitted equation from Step 2 to obtain the function:

[0047] V = x 4 +ux 2 +vx

[0048] In this function, u and v are respectively:

[0049]

[0050]

[0051] Step 4: Based on the data obtained in Step 3, calculate the following equations:

[0052] Δ=8u 3 +27v 2

[0053] When Δ = 0 in the equation, the reduction factor k′ = the safety factor k;

[0054] S7. Determine m different excavation sequences for multi-line parallel pipe jacking based on the number of pipes n. The specific method is as follows:

[0055] Calculate the minimum pipe cover thickness H based on the safety factor k for pipe cavity stability. min and minimum pipe gap width D min ;

[0056] When the pipe cover thickness H is at H min When <H, the interlayer thickness D between pipes is at D min When <D, determine the type of pipe jacking sequence.

[0057] Among them, the minimum pipe cover thickness H min The calculation method is as follows:

[0058] Using numerical calculation software, and inputting the basic parameters of the strata where the pipeline is located, calculations were performed. Pipe jacking excavation was conducted within the strata, and the least bisection method was used to calculate the pipeline cavern stability safety factor *k* for different pipeline overburden thicknesses. Based on the aforementioned cusp catastrophe theory, the pipeline overburden thickness when the pipeline cavern stability safety factor *k* = 1 can be obtained. When the pipeline cavern stability safety factor *k* = 1, the pipeline excavation is under ultimate stress, and the pipeline overburden thickness at this point is the minimum pipeline overburden thickness *H*. min .

[0059] The minimum inter-pipeline interlayer width D min The calculation method is as follows:

[0060] Set the pipe cover thickness to the minimum pipe cover thickness H. minUsing numerical calculation software, and inputting basic geological parameters, a double-line pipe jacking excavation was performed within the soil. The safety factor k for different pipe interlayer widths was calculated using the least bisection method. Based on the aforementioned cusp catastrophe theory, the pipe interlayer width when the safety factor k = 1 can be obtained. When the safety factor k = 1, the double-line pipe excavation is in the ultimate stress state, and the pipe interlayer width at this point is the minimum pipe interlayer width d for double-line pipe excavation. min .

[0061] Both single-hole and multi-hole pipelines undergo stress release during construction. The difference lies in the stress redistribution: single-hole pipeline construction results in only one stress redistribution, while multi-hole pipeline construction involves multiple stress redistributions. When the pipeline overburden thickness H is within H... min When <H, the mezzanine width D is at D min When the value is less than D, there will inevitably be construction influences between the construction of each pipe during the construction of a multi-hole pipeline. The pipe jacking construction of each pipe cannot be regarded as the construction of a single pipe. That is, there is an optimization of the construction sequence between multiple pipes.

[0062] S8. Calculate the safety factor K for the stability of the pipeline tunnel under various jacking sequence conditions (denoted as m conditions) for multi-line parallel pipelines. ij Where i takes the values ​​1, 2, 3, 4, ... m, and j takes the values ​​1, 2, 3, ... n;

[0063] S9. Compare the safety factor K for pipeline tunnel stability among different pipeline jacking sequences under the i-th working condition. ij (i = 1, 2, 3, ... m, j = 1, 2, 3, ... n) are selected sequentially, choosing the minimum value K of the pipeline safety factor under the i-th working condition. ijmin (i=1, 2, 3,...m, j=1, 2, 3,...n)

[0064] S10. Compare m K values ​​under m different working conditions. ijmin Given a set of numbers (i = 1, 2, 3, ..., m, j = 1, 2, 3, ..., n), select the minimum safety factor K for each of the m working conditions. ijmin The maximum value of max[K ijmin (i = 1, 2, 3, ... m, j = 1, 2, 3, ... n), the safe pipeline excavation sequence under the working conditions corresponding to this safety factor is the determined optimal multi-line parallel pipeline construction jacking sequence method.

[0065] The following explanation uses the example of n=3 pipes.

[0066] When the number of pipes n=3, the number of pipe jacking sequence conditions is 3, that is, there are three conditions, or three types of pipe jacking sequences. These three conditions are as follows: Figure 2 The three mentioned above can be expressed in words as follows:

[0067] Working condition 1: First construct the leftmost pipe, then the middle pipe, and finally the rightmost pipe;

[0068] Working condition 2: First construct the leftmost pipe, then the rightmost pipe, and finally the middle pipe;

[0069] Working condition 3: First construct the middle pipe, then the leftmost pipe, and finally the rightmost pipe.

[0070] Then, the safety factor K for different working conditions is calculated; the calculated safety factor K values ​​for the three working conditions are shown in the table below:

[0071]

[0072] In the table above, "1", "2", and "3" represent the construction sequence of the three pipelines. That is, K 11 =1.549, K 12 =1.181, K 13 =1.086; K 21 =1.549, K 23 =1.482, K 22 =1.089; K 32 =1.549, K 31 =1.181, K 33 =1.091, the minimum K value in working condition one is 1.086; the minimum K value in working condition two is 1.091; the minimum K value in working condition three is 1.089.

[0073] Results Analysis: Due to K 33 =1.091>K 22 =1.089>K 13 =1.086, so K 33 =1.091 corresponds to the optimal excavation sequence for working condition 3, which is to excavate the middle pipe first, then the leftmost pipe, and finally the rightmost pipe.

[0074] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for designing the jacking sequence in multi-line parallel pipeline construction, characterized in that, Includes the following steps: S1. Obtain the basic parameters of the multi-line parallel pipeline and the basic parameters of the strata where the pipeline is located. The basic parameters of the multi-line parallel pipeline include the number of pipelines n, the thickness of the overburden layer H, the diameter of the pipeline d, the width of the interlayer between pipelines D, and the external load q. The basic parameters of the strata where the pipeline is located include the elastic modulus E and Poisson's ratio. Severe Cohesion c and internal friction angle ; S2. Establish a numerical model of the stratigraphic structure with stress and deformation characteristics around multi-line parallel pipelines; S3. Based on the parameters obtained in S1 and the numerical model analysis of the stress deformation characteristics of the strata surrounding the multi-line parallel pipeline in S2, the stress state of the surrounding strata at any point after the pipeline excavation can be obtained, and the vertical displacement deformation value S1 at the pipeline arch can be recorded. S4. Combine cohesion c and internal friction angle After reduction, the reduced parameters are re-input into the numerical model for recalculation, and the vertical displacement deformation value S2 at the pipe arch is recorded. The reduction formula is as follows: in The reduced cohesion. This is the reduced internal friction angle. This is the reduction factor; S5. Combine cohesion c and internal friction angle The reduction is performed continuously according to the reduction formula in S4, and the reduced parameters are re-input into the numerical model for recalculation until the calculation fails to converge, indicating pipeline failure. During the calculation process, the vertical displacement deformation value at the pipeline arch after each reduction calculation is continuously recorded and denoted as . ; S6. Calculate the safety factor K for the stability of the pipeline cavern based on the obtained vertical displacement deformation value S at the top of the pipeline arch and the reduction factor k′. S7. The specific method for determining m different excavation sequences for multi-line parallel pipelines based on the number of pipelines n is as follows: Calculate the minimum pipe cover thickness H based on the safety factor k for pipe cavity stability. min and minimum pipe gap width D min ; When the pipe cover thickness H is at H min When <H, the interlayer thickness D between pipes is at D min When <D, determine the type of pipe jacking sequence; The minimum pipe cover thickness H min The calculation method is as follows: The basic parameters of the strata where the pipeline is located are input into the numerical calculation software, and the least bisection method is used to calculate the pipeline cavern stability safety factor k for different pipeline overburden thicknesses. The pipeline overburden thickness H is the minimum pipeline overburden thickness when k=1. min ; The minimum inter-pipeline interlayer width D min The calculation method is as follows: Set the pipe cover thickness to the minimum pipe cover thickness H. min Then, the basic geological parameters are input into the numerical calculation software, and the least bisection method is used to calculate the safety factor k of the pipe cavity stability for different pipe cavity widths. The pipe cavity width when k=1 is the minimum pipe cavity width D for double-line pipe excavation. min ; S8. Calculate the safety factor K for the stability of the pipeline tunnel under m different excavation sequences for multi-line parallel pipelines. ij Where i takes the values ​​1, 2, 3, 4, ... m, and j takes the values ​​1, 2, 3, ... n; S9. Compare the safety factor K for pipeline tunnel stability among different pipeline jacking sequences under the i-th working condition. ij The size of the safety factor K is selected sequentially for each pipeline under the i-th working condition, using the minimum value K. ijmin ; S10. Compare m K values ​​under m different working conditions. ijmin Size, select the minimum safety factor K under m working conditions ijmin The maximum value of max[K ijmin The safe pipeline excavation sequence corresponding to this safety factor under the working conditions is the determined optimal jacking sequence method for multi-line parallel pipeline construction.

2. The method for designing the jacking sequence of multi-line parallel pipeline construction according to claim 1, characterized in that: The numerical model of the stress and deformation characteristics of the strata surrounding the multi-line parallel pipeline in step S2 was obtained using Midas GTS NX numerical analysis software.

3. The method for designing the jacking sequence of multi-line parallel pipeline construction according to claim 1, characterized in that: Step S6 involves calculating the safety factor K for the stability of the pipeline cavity, specifically including the following steps: S61. Draw the Sk′ curve based on the obtained vertical displacement deformation value S at the top of the pipe arch and the reduction coefficient k′. S62. A fourth-order polynomial fitting was performed on the vertical displacement deformation value S of the surrounding strata crown and the multiple reduction coefficients k′ to obtain the fitting equation: S=a0+a1k′+a2k′ 2 +a3k′ 3 +a4k′ 4 In the formula, a0 to a4 are undetermined coefficients; S63. Standardize the fitted equation in step S62 to obtain the function: V=x 4 +ux 2 +vx Where u and v are respectively: S64. Based on the data obtained in step S63, calculate the following equations: Δ=8u 3 +27v 2 The reduction factor k′ when Δ=0 in the equation is the safety factor k.

Images