Method for determining and applying a loss control coefficient of a shield settlement ideal stratum

Abstract

This invention relates to a method for determining and applying the ideal ground loss control coefficient for shield tunnel settlement, comprising the following steps: collecting a dataset, calculating... I C , I B as well as I T Obtain the interval of I; obtain the initial ideal formation loss control coefficient. K 0 Calculate the formation loss coefficient; establish a numerical model to calculate formation subsidence; K Dynamic adjustment; obtained from the tunnel model K The database; calling the corresponding database based on the characteristic parameters of the target construction section. K The value is used as the initial ideal formation loss control coefficient input into the calculation model to calculate the formation volume convergence deformation and settlement response. This invention addresses the characteristic that differences in shield tunneling parameters across different sections lead to varying volume balance states in the cutterhead, shield body, and tail sections. It provides a unified core parameter basis, adaptable to parameter differences under different formations and operating conditions, yielding reasonable, accurate, and convergent results.

Description

Technical Field

[0001] This invention relates to the field of settlement control technology in shield tunneling construction, and in particular to a method for determining and applying the ideal ground loss control coefficient for shield tunneling settlement. Background Technology

[0002] With the continuous expansion of urban rail transit, suburban railways, and municipal underground space construction, the risks of constructing shield tunnels in soft strata, close proximity to existing railways and important buildings are becoming increasingly prominent. For example, in a shield tunneling project in a large city, the tunnel needs to run parallel to an existing railway over a long distance, with the closest horizontal distance in some areas being less than 10 meters. The overlying strata are mainly composed of silty soil, silty clay, and silty sand, making it highly susceptible to construction disturbances that could affect the stability of the existing high-speed railway subgrade. Therefore, high-precision and real-time settlement control methods have become crucial for construction safety.

[0003] Currently, the mainstream approach in this field is settlement control based on monitoring data and parameter inversion. This method analyzes the correlation between parameters such as tunneling speed, grouting volume, and soil removal volume and settlement results, and then uses on-site monitoring data to correct the model. However, this approach still has the following problems: 1) Although monitoring can be done in real time, control is still lagging behind, lacking feedforward and adaptive adjustment capabilities; 2) Inversion parameters rely on measured settlement data, making it impossible to achieve proactive control during construction; 3) A unified set of core parameters to describe the intensity of shield tunneling disturbance has not yet been established, making it difficult to achieve intelligent control; 4) A dynamically updated parameter database system is lacking, making it impossible to support rapid decision-making under different geological conditions and working conditions.

[0004] Ground settlement caused by shield tunneling is essentially controlled by multiple factors, including the balance of excavated soil in the cutterhead area, the filling of voids in the shield body area, and the synchronous grouting compensation in the tail area. Only when the control coefficients corresponding to the three key physical areas—the cutterhead area, the shield body area, and the tail area—are all within the ideal range can the ground loss caused by construction be effectively controlled, thereby achieving effective control over ground settlement and displacement. Based on this, this invention defines an ideal ground loss control coefficient K to comprehensively characterize the balance between ground volume loss and compensation during shield tunneling. Although existing technologies can monitor or analyze construction parameters such as advance speed, excavated soil volume, and grouting volume individually, they cannot yet be uniformly transformed into core parameters reflecting the ground loss control state. In particular, existing technologies lack an ideal ground loss control coefficient K that can comprehensively characterize the disturbance effects of the cutterhead area, the shield body area, and the tail area, and reflect the controllable settlement boundary. This makes it difficult to uniformly quantify the degree of construction disturbance under different segments and working conditions, and also makes it difficult to provide effective support for intelligent early warning and active control. Summary of the Invention

[0005] The purpose of this invention is to provide a method for determining and applying the ideal ground loss control coefficient for shield tunnel settlement, so as to solve the above-mentioned problems.

[0006] The technical solution of this invention is: a method for determining and applying the ideal ground loss control coefficient for shield tunnel settlement, comprising the following steps:

[0007] Step (1): Collect typical engineering datasets and calculate the cutterhead area balance coefficient I based on shield tunneling parameters for different sections. C Shield body area filling coefficient I B and shield tail zone filling coefficient I T According to I C I B I T Construct a set of characteristic parameters X for disturbance during shield tunneling construction, and define the ground loss coefficient I as a comprehensive mapping between the parameter set X and the ground loss control results to obtain the interval of I;

[0008] Step (2): Take the midpoint of the interval of I as the initial ideal formation loss control coefficient K0, which is used to calculate the formation loss coefficient and is equivalent to the volume shrinkage strain in the numerical simulation.

[0009] Step (3): Establish a numerical model that includes strata, tunnel and shield construction parameters and the strata loss coefficient to calculate strata settlement;

[0010] Step (4): Compare the numerically calculated settlement with the actual measured settlement calculation error. If the error exceeds the limit, use the bisection method to iteratively adjust K until the settlement threshold is met, thereby determining the range of K.

[0011] Step (5): Calculate the K value corresponding to each model unit of the tunnel model and establish a database of ideal stratum loss control coefficient K values;

[0012] Step (6): Based on the characteristic parameters of the target construction section, perform similarity matching in the K-value database to obtain the corresponding K-value or interval, and input it as the initial ideal formation loss control coefficient of the target section into the subsequent calculation model to calculate the formation volume convergence deformation and settlement response.

[0013] The balance coefficient I of the cutter head area C The calculation is shown in equation (1):

[0014] (1)

[0015] In the formula, ω is the rotational speed of the screw conveyor; m is the mass discharged per revolution of the screw conveyor; ρ is the soil density; v is the tunnel boring machine's advance speed; S0 is the over-excavation area; and S1 is the excavation area.

[0016] Shield area filling coefficient I BThe calculation is shown in equation (5):

[0017] (5)

[0018] In the formula Q mi S2 is the single-hole injection flow rate for the shield body; S2 is the axial projected area of ​​the shield body voids; v is the shield tunneling speed.

[0019] Shield tail zone filling coefficient I T The calculation is shown in equation (7):

[0020] (7)

[0021] Among them, Q gj S3 is the single-hole injection flow rate for synchronous grouting; S3 is the axial projected area of ​​the shield tail void; v is the shield advance speed.

[0022] The specific expression of the formation loss control coefficient I is shown in equation (11).

[0023] (11)

[0024] The formation loss coefficient I E The calculation is shown in equation (13):

[0025] (13)

[0026] In the formula, Δ V V represents the equivalent volume loss. t Where K is the theoretical excavation volume, I is the ideal formation loss control coefficient, and K is the formation loss control coefficient.

[0027] In step (4), the value of K in the bisection method is (a k +k) / 2 or (k+b) k ) / 2.

[0028] In step (5), the modeling units are divided, and the ideal formation loss control coefficient K corresponding to each modeling unit is obtained. i ; the K i The corresponding formation characteristic parameters, environmental characteristic parameters, and construction condition parameters are associated and stored to form a database of the ideal formation loss control coefficient K.

[0029] In step (6), the characteristic parameters of the target construction section include at least one or more of the following: stratum type, burial depth, overburden thickness, groundwater conditions, surrounding sensitive structures conditions, and advance speed, soil discharge volume and synchronous grouting volume.

[0030] This invention aims to more rationally determine the ideal ground loss control parameters in shield tunneling settlement control. Based on the theory of "ground loss control of ground settlement caused by shield tunneling construction," and addressing the differences in volume balance states between the cutterhead area, shield body area, and shield tail area due to variations in shield construction parameters across different sections, a method for determining and applying the ideal ground loss control coefficient for shield tunneling settlement is established. This invention can comprehensively utilize multi-source real-time construction parameters and numerical simulation results to achieve dynamic solution and fine calibration of the ideal ground loss control coefficient, yielding reasonable, highly accurate, and convergent results. Compared with existing methods relying on empirical indicators or post-hoc inversion, this invention has the following characteristics:

[0031] (1) Calculation of I based on the construction parameters of the partitioned sections C I B I T The calibration process, which establishes error constraints by defining the I interval with I and using K0 as the initial value, can adapt to parameter differences under different formations and operating conditions.

[0032] (2) The error of “numerical settlement - measured settlement” is used as a constraint, and the bisection method is used for adaptive iteration to make the solution process of K stable and convergent with strong repeatability;

[0033] (3) By establishing the K database, storage and retrieval across sections / projects can be realized, and dynamic correction based on newly added monitoring data can be supported, providing a unified core parameter basis for settlement simulation, risk control and parameter inversion. Attached Figure Description

[0034] Figure 1 This is a flowchart of the method of the present invention.

[0035] Figure 2 For I C I B I T The calculation results of I value changing over time (a) and the database of I (b).

[0036] Figure 3 Numerical simulation results for settlement prediction of the Airport Link Line Section 12 project: (a) Model displacement cloud map; (b) Settlement results of strata at a specific ring number.

[0037] Figure 4 The dynamic adaptive adjustment process for the ideal formation loss control coefficient K.

[0038] Figure 5 The process and results of establishing a database for the ideal formation loss control coefficient K. Detailed Implementation

[0039] 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.

[0040] A method for determining and applying the ideal ground loss control coefficient for shield tunnel settlement, including, for example... Figure 1 The steps shown in this embodiment are illustrated using the shield tunneling section of the Airport Link Line Section 12 as an example. The strata in this section mainly consist of silty clay, silty clay, and silty sand, with significant variations in the thickness of the overlying soil layer. This example selects the multi-source dataset already acquired from this project as the input data basis for the method of this invention, including real-time collected data on grouting volume, soil removal volume, screw conveyor speed, propulsion speed, and shield machine attitude information.

[0041] Step (1): Collect typical engineering datasets and calculate I based on shield tunneling construction parameters for different sections. C I B I T Find the value of I, determine the range of I, and establish a database of I.

[0042] Specifically, the collected datasets were organized, and key parameters constituting the mass and volume balance analysis were extracted. Statistical analysis was conducted on shield tunneling data from multiple rings in typical sections, and the cutterhead area balance coefficient I was calculated. C Shield body area filling coefficient I B and shield tail zone filling coefficient I T The time series distribution and value range of the data. Among them, the balance coefficient I of the cutterhead area. C The calculation is shown in equation (1):

[0043] (1)

[0044] In the formula, ω is the rotational speed of the screw conveyor (obtained from the shield machine data acquisition system); m is the mass discharged by the screw conveyor in a single revolution, as shown in formula (2); ρ is the density of the stratum (provided by engineering geological survey data); v is the shield advance speed (obtained from the shield machine data acquisition system); S0 is the over-excavation area, as shown in formula (3); S1 is the excavation area, as shown in formula (4).

[0045] (2)

[0046] In the formula, β is the inclination coefficient (obtained from the shield machine data acquisition system), φ is the slag filling coefficient (obtained from the shield machine data acquisition system), D is the effective radius of the auger blade, and H is the auger pitch.

[0047] (3)

[0048] (4)

[0049] In the formula, r is the cutterhead excavation diameter, l is the over-excavation cutter extension, and θ is the over-excavation angle.

[0050] Shield area filling coefficient I B The calculation is shown in equation (5):

[0051] (5)

[0052] In the formula Q mi The injection flow rate of the single hole (i-th hole) of the shield body is monitored by the flow sensor on the mud injection pipeline; S2 is the axial projected area of ​​the shield body void, as shown in Equation (6); v is the shield advance speed (obtained from the shield machine data acquisition system).

[0053] (6)

[0054] In the formula, S1 is the excavation area and d1 is the diameter of the shield.

[0055] Shield tail zone filling coefficient I T The calculation is shown in equation (7):

[0056] (7)

[0057] Among them, Q gj The flow rate injected into the synchronous grouting single hole (the i-th synchronous grouting hole) is monitored by the flow sensor on the grouting pipeline; S3 is the axial projected area of ​​the shield tail gap, as shown in Equation (8); v is the shield advance speed.

[0058] (8)

[0059] In the formula, S1 is the excavation area and d2 is the outer diameter of the segment.

[0060] According to I C I B I T The formation loss coefficient I is calculated based on the combination relationship, and its mean, extreme values, and variance characteristics are obtained, such as... Figure 3 As shown.

[0061] The formation loss coefficient I is not directly determined by a single construction parameter, but rather by the cutterhead zone control parameter I. C Shield body area control parameters I B and shield tail zone control parameters I TThe comprehensive characterization result formed by the combined effects. To this end, the present invention first constructs a set of characteristic parameters of shield tunneling disturbance, as shown in equation (9).

[0062] (9)

[0063] Based on this, the formation loss coefficient I is defined as a comprehensive mapping between the parameter set X and the formation loss control result, as shown in Equation (10).

[0064] (10)

[0065] Wherein, Φ(X) represents the comprehensive mapping function, used to describe the formation loss state under the combined effects of construction disturbance in the cutterhead area, shield body area, and shield tail area. This expression indicates that I is essentially a unified quantitative result after multi-regional and multi-parameter coupling effects, rather than a simple characterization of single parameters such as advance speed, soil removal volume, or grouting volume. Based on this, the specific expression of the formation loss control coefficient I is shown in equation (11).

[0066] (11)

[0067] like Figure 2 As shown, there are significant differences in the construction disturbance characteristics between different segments of this interval, with a large range of parameter fluctuations, reflecting the significant impact of changes in formation conditions, grouting status, and construction conditions on the degree of disturbance.

[0068] Step (2): Take the midpoint of the interval of I as the initial ideal formation loss control coefficient K0, which is used to calculate the formation loss coefficient and is equivalent to the volumetric shrinkage strain in the numerical simulation.

[0069] Based on the statistical analysis of the above I values, an I value database is constructed, with a range of [1.42, 1.82]. The median of this range is used as the initial estimate of the ideal formation loss control coefficient K, as shown in equation (12):

[0070] (12)

[0071] In the formula I min I is the minimum value in the interval. max This represents the maximum value within the interval. In this example, the initial value of K, K0, is set to 1.62.

[0072] Calculate the formation loss coefficient I according to formula (11) E The value was equivalent to the volumetric shrinkage strain in the numerical model, and then substituted into the numerical model to calculate the surface settlement. The result was then compared with the actual settlement data measured on site.

[0073] (13)

[0074] In the formula, Δ V V represents the equivalent volume loss. t Where K is the theoretical excavation volume, I is the ideal formation loss control coefficient, and K is the formation loss control coefficient.

[0075] Step (3): Establish a numerical model that includes strata, tunnel and shield construction parameters, and the strata loss coefficient to calculate strata settlement. In this embodiment, PLAXIS 3D software is selected to establish the numerical model.

[0076] Step (4): Compare the numerically calculated settlement with the actual measured settlement on site. If the error exceeds the limit, use the bisection method to iteratively adjust K until the settlement threshold is met, thereby determining the range of K.

[0077] Preliminary calculations show that there is a certain deviation between the numerical model results and the measured values, such as... Figure 3 As shown, the K value needs to be calibrated. Therefore, the dynamic adaptive adjustment strategy proposed in this invention is adopted, which involves iteratively optimizing the K value using a bisection method and recalculating the numerical value until the error between simulated and measured settlement meets a preset threshold. Finally, the ideal formation loss control coefficient K, after inversion calibration, is obtained. The dynamic adaptive adjustment process is as follows: Figure 4 As shown: the value of K in the bisection method is (a k +k) / 2 or (k+b) k ) / 2.

[0078] Step (5): Taking each 10-20 rings as a model unit, calculate and obtain the corresponding K for each unit. i The values ​​are then compiled and a database of ideal formation loss control coefficient K values ​​is established.

[0079] Specifically, a database of ideal formation loss control coefficients K should be established. For example... Figure 5 As shown, each modeling unit consists of 10 to 20 rings. Numerical models are constructed for each modeling unit, and dynamically and adaptively adjusted based on the geological conditions, construction conditions, and monitoring feedback results of the corresponding section to obtain the ideal geological loss control coefficient K for each modeling unit. i The K i The corresponding formation characteristic parameters, environmental characteristic parameters, and construction condition parameters are associated and stored to form a database of the ideal formation loss control coefficient K.

[0080] Step (6): The database is used to establish a mapping relationship between the ideal formation loss control coefficient K and the characteristics of the target construction section; wherein, the characteristics of the target construction section include at least one or more of the following: formation type, burial depth, overburden thickness, groundwater conditions, surrounding sensitive structures, and advancing speed, soil removal volume, and synchronous grouting volume. When invoked, similarity matching is performed in the database based on the characteristic parameters of the target construction section to obtain the corresponding K. i The value or K i The range of values ​​is selected and used as the initial ideal formation loss control coefficient for the target section. This coefficient is then input into the subsequent calculation model to calculate the formation volume convergence deformation and settlement response. Subsequently, the K value is corrected and updated by combining real-time monitoring data.

[0081] In this embodiment, the final range of the K-value database within the project interval is determined to be [1.53, 1.93]. Through the above method, the ideal formation loss control coefficient K is achieved through partitioned database construction, on-demand retrieval, and dynamic updating, providing parameter support for formation settlement prediction and construction risk early warning.

[0082] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and not restrictive.

Claims

1. A method for determining and applying the ideal ground loss control coefficient for shield tunnel settlement, characterized in that, Includes the following steps: Step (1): Collect typical engineering datasets and calculate the cutterhead area balance coefficient I based on shield tunneling parameters for different sections. C Shield body area filling coefficient I B and shield tail zone filling coefficient I T According to I C I B I T Construct a set of characteristic parameters X for disturbance during shield tunneling construction, and define the ground loss coefficient I as a comprehensive mapping between the parameter set X and the ground loss control results to obtain the interval of I; Step (2): Take the midpoint of the interval of I as the initial ideal formation loss control coefficient K0, which is used to calculate the formation loss coefficient and is equivalent to the volume shrinkage strain in the numerical simulation. Step (3): Establish a numerical model that includes strata, tunnel and shield construction parameters and the strata loss coefficient to calculate strata settlement; Step (4): Compare the numerically calculated settlement with the actual measured settlement on site. If the error exceeds the limit, use the bisection method to iteratively adjust K until the settlement threshold is met, thereby determining the range of K. Step (5): Calculate the K value corresponding to each model unit of the tunnel model and establish a database of ideal stratum loss control coefficient K values; Step (6): Based on the characteristic parameters of the target construction section, perform similarity matching in the K-value database to obtain the corresponding K-value or interval, and input it as the initial ideal formation loss control coefficient of the target section into the subsequent calculation model to calculate the formation volume convergence deformation and settlement response.

2. The method for determining and applying the ideal ground loss control coefficient for shield tunnel settlement according to claim 1, characterized in that, The balance coefficient I of the cutter head area C The calculation is shown in equation (1): （1） In the formula, ω is the rotational speed of the screw conveyor; m is the mass discharged per revolution of the screw conveyor; ρ is the soil density; v is the tunnel boring machine's advance speed; S0 is the over-excavation area; and S1 is the excavation area. Shield area filling coefficient I B The calculation is shown in equation (5): （5） In the formula Q mi S2 is the single-hole injection flow rate for the shield body; S2 is the axial projected area of ​​the shield body voids; v is the shield tunneling speed. Shield tail zone filling coefficient I T The calculation is shown in equation (7): （7） Among them, Q gj S3 is the single-hole injection flow rate for synchronous grouting; S3 is the axial projected area of ​​the shield tail void; v is the shield advance speed.

3. The method for determining and applying the ideal ground loss control coefficient for shield tunnel settlement according to claim 2, characterized in that, The specific expression of the formation loss control coefficient I is shown in equation (11). (11).

4. The method for determining and applying the ideal ground loss control coefficient for shield tunnel settlement according to claim 3, characterized in that, The formation loss coefficient I E The calculation is shown in equation (13): （13） In the formula, Δ V V represents the equivalent volume loss. t Where K is the theoretical excavation volume, I is the ideal formation loss control coefficient, and K is the formation loss control coefficient.

5. The method for determining and applying the ideal ground loss control coefficient for shield tunnel settlement according to claim 1, characterized in that, In step (4), the value of K in the bisection method is (a k +k) / 2 or (k+b) k ) / 2.

6. The method for determining and applying the ideal ground loss control coefficient for shield tunnel settlement according to claim 1, characterized in that, In step (5), the modeling units are divided, and the ideal formation loss control coefficient K corresponding to each modeling unit is obtained. i ; the K i The corresponding formation characteristic parameters, environmental characteristic parameters, and construction condition parameters are associated and stored to form a database of the ideal formation loss control coefficient K.

7. The method for determining and applying the ideal ground loss control coefficient for shield tunnel settlement according to claim 1, characterized in that, In step (6), the characteristic parameters of the target construction section include at least one or more of the following: stratum type, burial depth, overburden thickness, groundwater conditions, surrounding sensitive structures conditions, and advance speed, soil discharge volume and synchronous grouting volume.

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