Theoretical calculation method for influence of stratum additional stress by using all-inhomogeneous gram mud effect construction method

Abstract

The invention discloses a theoretical calculation method for the influence of a total non-uniform gram mud effect construction method on stratum additional stress, and relates to the technical field. Comprising the following steps: S1, establishing a model; and S2, based on the model established in the step S1, analyzing the stratum settlement additional stress caused by shield tunneling. According to the method, the model is established, and the additional stress deformation in the stratum caused by the over-excavation gap of the shield and the shield tail integration gap is finally calculated, so that a second use method of using the mud-resisting effect construction method is known and judged, namely, the influence of further filling the shield tail integration gap on the additional stress of the stratum is known and judged.

Description

Technical Field

[0001] This invention belongs to the field of shield tunneling technology, and more specifically, it relates to a theoretical calculation method for the influence of the fully non-uniform mud-effect method on the additional stress of the stratum. Background Technology

[0002] Due to its convenience and safety, the shield tunneling method is increasingly widely used in underground structural engineering, especially tunnel engineering. With the development of technology and changing demands, the diameter of traditional shield tunneling machines is constantly increasing, reaching up to 16 meters. However, this increase in diameter also brings a series of engineering challenges. The main purpose of proposing the mud-effect method is to solve the practical engineering problem of excessive soil voids caused by large shield tunneling, leading to excessive ground settlement and seriously affecting the surface soil and internal structures or buildings.

[0003] When designing a tunnel boring machine (TBM), engineers typically set the cutterhead diameter slightly larger than the outer diameter of the shield shell to ensure smooth tunneling. During tunneling, some TBM routes require small-radius turns, necessitating the use of an over-cutting cutterhead. Both of these situations result in gaps behind the cutterhead and on the outer surface of the shield shell. The first application of the grouting method involves filling the area behind the cutterhead or the shield shell with grout from the inside out to ensure the gaps are filled and control ground settlement. This method is widely used in current TBM projects, especially in large or super-large TBMs. To ensure smooth demolding of the shield end sections, the outer diameter of the segments after simultaneous grouting must be smaller than the inner diameter of the shield. The second application of the grouting method involves injecting grout again outside the simultaneous grouting to further fill the integrated tail section (IGST). This second method is rarely used currently, but based on available data, it has been used in TBM projects for the Shanghai Metro.

[0004] The two methods have many limitations and requirements in practical engineering applications. The main purpose of the first method is to fill the void behind the cutterhead. However, the actual filling situation cannot be determined through visual inspection or monitoring. The main control quantity is limited to the amount of slurry used; generally, the void should ideally be completely filled on-site. The first method is more commonly used and more effective in controlling the strata. The biggest limitation of the second grouting method is the limited operating space, making it more advantageous in large and super-large shield tunnels. Although the grouting effect of the second method is intuitive, its specific strata control effect is unclear, and it is rarely used. Therefore, it is necessary to discuss the specific scope, form, and effect of the second grouting method. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a theoretical calculation method for the influence of the full non-uniform mud-effect method on the additional stress of the formation. This method establishes a model and finally calculates the amount of deformation of the internal additional stress of the formation caused by the over-excavation gap of the shield and the shield tail integration gap. In this way, we can understand and judge the influence of the second method of using the mud-effect method, namely, further filling the shield tail integration gap, on the additional stress of the formation.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a theoretical calculation method for the influence of the fully non-uniform mud-effect method on the additional stress of the formation, comprising the following steps:

[0007] S1. Establishing a Model

[0008] The cladding layer is cast inside the shield tail after the tunnel segments are assembled. The casting area is the upper half of the entire shield segment, and the casting thickness is uneven. The cladding layer is the thickest at the very top of the shield segment, and its thickness decreases uniformly as the height of each point on the shield segment decreases, and the outer curve of the cladding layer becomes elliptical. The grouting ring has a uniform thickness and is divided into upper and lower parts. It is circular in the lower half of the shield segment and becomes elliptical in the upper half of the segment along with the cladding layer. The shield segment, cladding layer, and grouting layer do not exceed the shield excavation range, and the segment and cladding layer can be normally removed from the shield tail. The contact points between the above-built model and the shield excavation range are C and D, where point C is the highest point and point D is the lowest point, resulting in the following formula:

[0009] (1)

[0010] (2)

[0011] In the formula, r is the outer diameter of the tube segment, and h c h is the thickness of the mud-effect layer. g The thickness of the synchronous grouting layer is given by R, where R is the diameter of the tunnel boring machine, and h is the diameter of the shield tunneling machine. s The thickness of the tunnel boring machine's outer shell;

[0012] To ensure that the shield tail integration gap (IGST) is filled with synchronous grout as much as possible, the design is carried out by directly taking the equal sign when using formula (1) and formula (2) for calculation;

[0013] S2. Based on the model established in step S1, analyze the additional stress caused by ground settlement during shield tunneling:

[0014] The equations for each interface are as follows:

[0015] Super-dig interface:

[0016] Excavation interface:

[0017] Kelp Effect Interface:

[0018] On the grouting interface:

[0019] Below the grouting interface:

[0020] Inner side of the segment:

[0021] outer side of the segment:

[0022] The internal spatial gap between the excavation interface and the grouting interface represents the soil loss caused by the shield tunneling under the model established in step S1. Combining this with the existing rewritten three-dimensional semi-infinite elastic general solution, a triple integral is performed in three-dimensional coordinates on the internal spatial gap between the excavation interface and the grouting interface to obtain the analytical solution of the additional stress caused by the ground settlement due to shield tunneling under the model established in step S1; the shield tail integration gap... The additional stress caused by soil loss in each part of the stratum due to the lack of mud-effect grouting was calculated by substituting the values ​​into the calculation:

[0023] Additional stress caused by ground settlement due to over-excavation gaps:

[0024] (3)

[0025] Additional stress on formation settlement caused by the shield tail conformity gap (IGST):

[0026] (4)

[0027] In the formula, This is an extension of the analytical solution for vertical settlement at any point inside the stratum caused by a void in the soil under semi-infinite conditions, derived by Sagaseta, combined with the Cerruti solution. It is a semi-infinite range rewrite of the analytical solution for various additional stresses at any point inside the stratum caused by a void in the soil. 1 represents the radians after the segment length has been converted. For the slope of the tunnel boring machine, This refers to the turning radius of the tunnel boring machine within this section. This refers to the actual over-excavation gap. This represents the initial burial depth of the tunnel boring machine.

[0028] The beneficial effects of adopting the above technical solution are as follows: In shield tunneling, especially in large shield tunneling projects, the grouting behind the shield wall directly determines the stability of the strata where the shield is located. The use of the mud-effect method is basically accompanied by shield tunneling, but the application of the mud-effect method mainly relies on the experience of engineers and lacks a systematic guidance method. The method of this invention provides a theoretical approach for the specific application of the mud-effect method in shield tunneling, connecting the mud-effect dosage and method with the additional stress inside the strata, thus providing a safety guarantee for the control of additional stress on the construction site. At the same time, this method can also serve as an important theoretical indicator for judging the effectiveness of the mud-effect method, helping to deal with practical problems encountered on site in a timely manner, and solving practical problems on site from a theoretical perspective. Attached Figure Description

[0029] Figure 1 This is the instruction manual for the mud-effect construction method;

[0030] Figure 2 It is a "sinking shield" section that uses all non-uniform mud-effect construction methods;

[0031] Figure 3 This is a schematic diagram of the boundaries of the shield tunnel cross section under all non-uniform mud-effect construction methods. Detailed Implementation

[0032] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0033] All non-uniform mud-effect construction methods such as Figure 1 As shown, the grouting layer still covers the upper half of the entire tunnel segment, but it is not uniform. Specifically, it is thickest at the top of the segment, and decreases uniformly as the height of each point on the tunnel segment decreases. Under these conditions, the outer curve of the grouting layer becomes an ellipse. At the same time, the grouting ring, due to its uniform thickness, is also divided into two parts. It remains circular in the lower half of the segment, while in the upper half, it becomes elliptical due to the grouting layer.

[0034] The parameters of the tunnel boring machine (TBM) in this model have relatively simple constraints and relationships. The remaining requirements are to ensure that the segments, slurry layer, and grouting layer do not exceed the TBM's excavation range, and that the segments and slurry layer can exit the shield tail normally. The contact points between this model and the TBM's excavation range are points C and D shown in the diagram, representing the highest and lowest points, respectively. Therefore, the above parameters have the following interrelationships:

[0035] (1)

[0036] (2)

[0037] In the formula, r is the outer diameter of the tube segment, and h c h is the thickness of the mud-effect layer. g The thickness of the synchronous grouting layer is given by R, where R is the diameter of the tunnel boring machine, and h is the diameter of the shield tunneling machine. s This refers to the thickness of the tunnel boring machine's outer shell.

[0038] As shown in the figure, the internal space gap between the excavation interface and the grouting interface represents the soil loss caused by shield tunneling in this model. Combining this with the existing rewritten three-dimensional semi-infinite elastic general solution, we perform a triple integral in three-dimensional coordinates on this gap to obtain the analytical solution for ground settlement caused by shield tunneling in this model. It is worth noting that, for ease of calculation, the shield tail integration gap... The values ​​were substituted into the calculations without the use of mud-effect grouting.

[0039] The equations for each interface are as follows:

[0040] Super-dig interface:

[0041] Excavation interface:

[0042] Kelp Effect Interface:

[0043] On the grouting interface:

[0044] Below the grouting interface:

[0045] Inner side of the segment:

[0046] outer side of the segment:

[0047] Additional stress caused by ground settlement due to over-excavation gaps:

[0048] (3)

[0049] Additional stress on formation settlement caused by the shield tail conformity gap (IGST):

[0050] (4)

[0051] In the formula, This is an extension of the analytical solution for vertical settlement at any point inside the stratum caused by a void in the soil under semi-infinite conditions, derived by Sagaseta, combined with the Cerruti solution. It is a semi-infinite range rewrite of the analytical solution for various additional stresses at any point inside the stratum caused by a void in the soil. 1 represents the radians after the segment length has been converted. For the slope of the tunnel boring machine, This refers to the turning radius of the tunnel boring machine within this section. This refers to the actual over-excavation gap. This represents the initial burial depth of the tunnel boring machine.

[0052] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A theoretical calculation method for the influence of a fully non-uniform mud-effect method on formation additional stress, characterized in that, Includes the following steps: S1. Establishing a Model The cladding layer is cast inside the shield tail after the tunnel segments are assembled. The casting area is the upper half of the entire shield segment, and the casting thickness is uneven. The cladding layer is the thickest at the very top of the shield segment, and its thickness decreases uniformly as the height of each point on the shield segment decreases, and the outer curve of the cladding layer becomes elliptical. The grouting ring has a uniform thickness and is divided into upper and lower parts. It is circular in the lower half of the shield segment and becomes elliptical in the upper half of the segment along with the cladding layer. The shield segment, cladding layer, and grouting layer do not exceed the shield excavation range, and the segment and cladding layer can be normally removed from the shield tail. The contact points between the above-built model and the shield excavation range are C and D, where point C is the highest point and point D is the lowest point, resulting in the following formula: r+h c +h g ≤R (1) r+h c ≤R-h s (2) In the formula, r is the outer diameter of the tube segment, and h c h is the thickness of the mud-effect layer. g The thickness of the synchronous grouting layer is given by R, where R is the diameter of the tunnel boring machine, and h is the diameter of the shield tunneling machine. s The thickness of the tunnel boring machine's outer shell; To ensure that the shield tail integration gap (IGST) is filled with synchronous grout as much as possible, the design is carried out by directly taking the equal sign when using formula (1) and formula (2) for calculation; S2. Based on the model established in step S1, analyze the additional stress caused by ground settlement during shield tunneling: The equations for each interface are as follows: Super mining interface: (xQ) 2 +(zh) 2 =(R+ω) 2 Excavation interface: (xQ) 2 +(zh) 2 =R 2 Kelp Effect Interface: On the grouting interface: Below the grouting interface: Inside of the segment: outer side of the segment: The internal spatial gap between the excavation interface and the grouting interface represents the soil loss caused by the shield tunneling under the model established in step S1. Combining the existing rewritten three-dimensional semi-infinite elastic general solution, a triple integral is performed in three-dimensional coordinates on the internal spatial gap between the excavation interface and the grouting interface to obtain the analytical analysis of the additional stress on ground settlement caused by the shield tunneling under the model established in step S1. The calculation of the additional stress on ground settlement caused by soil loss in each part is as follows: Additional stress caused by ground settlement due to over-excavation gaps: Additional stress on formation settlement caused by the shield tail conformity gap (IGST): In the formula, σ m This is an extension of the analytical solution for vertical settlement at any point within the stratum caused by a void in the soil under semi-infinite conditions, derived by Sagaseta. It is combined with the Cerruti solution to obtain a semi-infinite range rewritten analytical solution for various additional stresses at any point within the stratum caused by a void in the soil. θ1 is the radian after the section length conversion, β is the shield tunneling slope, Q is the turning radius of the shield machine in this section, ω is the actual overcut gap, h is the initial shield burial depth, and G is the tail integration gap. t The values ​​were substituted into the calculations without the use of mud-effect grouting.

Images