A prediction method for lateral displacement of surrounding rock caused by steep slope TBM construction

Abstract

The present invention discloses a method for predicting the lateral displacement of surrounding rock caused by high-slope TBM construction, comprising the following steps: based on the three-dimensional random medium theory, deriving a theoretical formula for the lateral deformation of surrounding rock caused by surrounding rock loss during tunneling by TBM; establishing a three-dimensional spatial model of a high-slope tunnel, combining the construction path of the high-slope tunnel, the outer diameter R of the TBM and the percentage of stratum loss; or , and obtain the radius of the tunnel's surrounding rock convergence deformation boundary r ; The unit volume "gap" generated by the surrounding rock loss is integrated in the volume domain of the actual three-dimensional construction gap to obtain the calculation formula for the lateral displacement of the surrounding rock caused by the three-dimensional construction gap of the TBM. The advantages of the present invention are: based on the three-dimensional random medium theory, it fully considers the actual construction characteristics of the large-slope TBM, can accurately predict the lateral displacement of the surrounding rock, and provides a research basis for the calculation method of surrounding rock deformation caused by the asymmetric surrounding rock loss on the horizon in the future.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel engineering, and in particular relates to a method for predicting lateral displacement of surrounding rock caused by large-slope TBM construction. Background Art

[0002] Shield or TBM (full-section hard rock tunnel boring machine) construction has the advantage of little impact on surrounding rock deformation. Currently, there are many prediction devices and methods for surrounding rock deformation caused by TBM construction gaps, but most of the projects are straight tunnels in the horizontal plane, and the main equipment and storage media are used to obtain vertical deformation of surrounding rocks. There are few prediction devices or methods for lateral displacement of surrounding rocks caused by construction gaps in steep tunnels. For shield or TBM excavation along steep paths, the tunnel axis elevation is constantly changing, and conventional prediction methods are obviously not applicable. Summary of the invention

[0003] The purpose of the present invention is to provide a method for predicting the lateral displacement of surrounding rock caused by steep slope TBM construction in light of the deficiencies in the above-mentioned prior art. The prediction method can accurately calculate the convergence deformation boundary of the surrounding rock caused by the three-dimensional construction gap of the TBM in three-dimensional space by combining the construction process of the TBM during excavation along the steep slope construction path, thereby accurately predicting the lateral displacement of the surrounding rock caused by the three-dimensional construction gap of the TBM.

[0004] The purpose of the present invention is achieved by the following technical solutions:

[0005] A method for predicting lateral displacement of surrounding rock caused by steep slope TBM construction, characterized in that the prediction method comprises the following steps:

[0006] (1) The TBM excavates a tunnel along a steep construction path, and based on the three-dimensional random medium theory, a theoretical formula for the lateral deformation of the surrounding rock caused by the surrounding rock loss when the TBM excavates the tunnel is derived; wherein the steep slope in the steep construction path refers to the angle γ between the axis of the tunnel and the horizontal straight line;

[0007] (2) establishing a three-dimensional spatial model of a steep-slope tunnel, and obtaining the radius r of the surrounding rock convergence deformation boundary of the tunnel by combining the steep-slope tunnel construction path, the TBM outer diameter R, and the formation loss percentage η;

[0008] (3) Integrating the unit volume "void" generated by the surrounding rock loss within the volume domain of the actual three-dimensional construction gap to obtain a calculation formula for the lateral displacement of the surrounding rock caused by the three-dimensional construction gap of the TBM.

[0009] Step (1) comprises the following steps:

[0010] Establish a three-dimensional rectangular coordinate system, where the origin of the coordinate system and the x-axis and y-axis are all located on the horizontal surface, and the z-axis is vertically downward; assume that point F(x 0 ,y 0 ,z 0 ), the lateral displacements of any point P(x,y,z) in the deep surrounding rock along the x-axis and y-axis caused by the unit volume void are:

[0011]

[0012]

[0013] Where:

[0014] β is the main influencing angle of the surrounding rock above the tunnel, and its value is determined by referring to geological survey data.

[0015] Step (2) comprises the following steps:

[0016] The three-dimensional spatial model of the steep-slope tunnel is established. The slope of the tunnel is γ, and it is agreed that the TBM excavating downward is positive and excavating upward is negative; the buried depth of the center of the tunnel face is h; the buried depth at the x coordinate on the tunnel axis is a non-fixed value that varies with x and γ; F(x 0 ,y 0 ,z 0 ) at the buried depth h(x 0 ) is calculated as:

[0017] h(x 0 )=h+x 0 tanγ

[0018] The length of the TBM excavation along the steep slope construction path is l, and the three-dimensional construction gap generated by the TBM after excavation without support is V s , the calculation formula is:

[0019] V s =ηπR 2

[0020] Where: R is the outer diameter of the TBM; η is the formation loss percentage;

[0021] According to the uniform stratum movement mode, the radius r of the surrounding rock convergence deformation boundary is obtained, and the calculation formula is:

[0022]

[0023] Step (3) comprises the following steps:

[0024] The unit volume "gap" obtained in step (1) is integrated in the volume domain of the three-dimensional construction gap in step (2), wherein the volume domain includes the space volume A enclosed by the TBM boundary ring along the tunnel axis for a distance of l and the space volume B enclosed by the surrounding rock convergence deformation boundary along the tunnel axis for a distance of l. The space volume A is subtracted from the space volume B to obtain the calculation formulas for the lateral displacement of the surrounding rock along the x-axis and the y-axis caused by the three-dimensional construction gap during the TBM excavation process, respectively:

[0025]

[0026]

[0027] The advantages of the present invention are: based on the three-dimensional random medium theory, the actual construction characteristics of large-slope TBM are fully considered, the lateral displacement of surrounding rock can be accurately predicted, and a research basis is provided for the calculation method of surrounding rock deformation caused by asymmetric surrounding rock loss on the horizon in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic flow chart of a method for predicting lateral displacement of surrounding rock caused by large-slope TBM construction in the present invention;

[0029] Figure 2 It is a schematic diagram of a three-dimensional rectangular coordinate system in the present invention;

[0030] Figure 3 Schematic diagram of the convergent deformation boundary of the TBM boundary and the surrounding rock in the present invention. DETAILED DESCRIPTION

[0031] The features of the present invention and other related features are further described in detail below through embodiments in conjunction with the accompanying drawings to facilitate understanding by those skilled in the art:

[0032] like Figure 1-3 , the marks in the figure are: R is the outer diameter of TBM; r is the radius of the convergent deformation boundary of the surrounding rock;.

[0033] Example: Figure 1 , 2 As shown in FIG. 3 , this embodiment specifically relates to a method for predicting lateral displacement of surrounding rock caused by large-slope TBM construction, and the prediction method mainly includes the following steps:

[0034] (1) When a TBM excavates a tunnel along a steep construction path, based on the three-dimensional random medium theory proposed by Litwiniszyn, a theoretical formula for the lateral deformation of the surrounding rock caused by the surrounding rock loss (i.e., the unit volume "voids" in the elastic semi-infinite body) during TBM tunneling is derived. The steep construction path here refers to the angle γ between the axis of the tunnel and the horizontal line. The specific method is described as follows:

[0035] Based on the three-dimensional random medium theory proposed by Litwiniszyn, a three-dimensional rectangular coordinate system is established. The origin of the coordinate system and the x-axis and y-axis are all located on the horizontal surface, and the z-axis is vertically downward. Assume that point F(x 0 ,y 0 ,z 0 ), the lateral displacements along the x-axis and y-axis at any point P(x,y,z) in the deep surrounding rock are:

[0036]

[0037]

[0038] Where:

[0039] β is the main influence angle of the surrounding rock above the tunnel, and its value is determined by consulting geological survey data;

[0040] The deep surrounding rock mentioned above refers to the strata below the surface (x, y, 0). Other two-dimensional theories obtain the displacement at the surface, while the three-dimensional theory can obtain the displacement of the strata below the surface.

[0041] (2) A three-dimensional spatial model of a steep-slope tunnel is established. The radius r of the tunnel's surrounding rock convergence deformation boundary is obtained by combining the steep-slope tunnel construction path, TBM outer diameter R, and stratum loss percentage η. The specific method is described as follows:

[0042] A three-dimensional spatial model of a steep tunnel is established. The slope of the tunnel is γ, in degrees. It is agreed that the TBM excavating downward is positive and excavating upward is negative. The buried depth of the center of the tunnel face is h, in meters. The buried depth at the x coordinate on the tunnel axis is a non-fixed value that varies with x and γ. This embodiment only discusses the point F(x 0 ,y 0 ,z 0 ) at the buried depth h(x 0 ) is calculated as:

[0043] h(x 0 )=h+x 0 tanγ.

[0044] The length of the TBM excavation along the steep slope construction path is l, in meters. Assuming that the TBM is not supported in time after excavation, the resulting three-dimensional construction gap (unit length) is V s , the calculation formula is:

[0045] V s =ηπR 2

[0046] Where: R is the outer diameter of the TBM; η is the percentage of formation loss, which is assumed to have nothing to do with the burial depth of the TBM, but only with the engineering geological conditions and other factors such as construction technology.

[0047] According to the uniform stratum movement mode, the radius r of the surrounding rock convergence deformation boundary is obtained, and the calculation formula is:

[0048]

[0049] (3) The unit volume “void” generated by the surrounding rock loss is integrated in the volume domain of the actual three-dimensional construction gap to obtain a calculation formula for the lateral displacement of the surrounding rock caused by the three-dimensional construction gap of the TBM. The specific method is described in detail as follows:

[0050] The unit volume "gap" obtained in step (1) is integrated in the volume domain of the three-dimensional construction gap in step (2). The volume domain is divided into two parts, including the space volume A enclosed by the TBM boundary ring along the tunnel axis for a distance of l and the space volume B enclosed by the surrounding rock convergence deformation boundary along the tunnel axis for a distance of l. The space volume A is subtracted from the space volume B to obtain the calculation formulas for the lateral displacement of the surrounding rock along the x-axis and y-axis caused by the three-dimensional construction gap during the TBM excavation process, respectively:

[0051]

[0052]

[0053] Compared with the prior art, the prediction device for the lateral displacement of surrounding rock caused by the construction gap in a steep slope tunnel described in the present invention proposes a prediction formula for the lateral displacement of surrounding rock caused by the three-dimensional construction gap when a shield or TBM is excavating along a steep slope path based on the three-dimensional random medium theory. Combined with the steep slope tunnel construction path, it can accurately calculate the lateral displacement of surrounding rock caused by the TBM construction gap in three-dimensional space, and can provide a more practical answer for predicting the deformation of tunnel surrounding rock.

Claims

1. A prediction method for lateral displacement of surrounding rock caused by high-slope TBM construction. Features The prediction method comprises the following steps: (1) The TBM excavates a tunnel along a steep construction path, and based on the three-dimensional random medium theory, a theoretical formula for the lateral deformation of the surrounding rock caused by the surrounding rock loss when the TBM excavates the tunnel is derived; wherein the steep slope in the steep construction path refers to the angle γ between the axis of the tunnel and the horizontal straight line; (2) establishing a three-dimensional spatial model of a steep-slope tunnel, and obtaining the radius r of the surrounding rock convergence deformation boundary of the tunnel by combining the steep-slope tunnel construction path, the TBM outer diameter R, and the formation loss percentage η; (3) Integrating the unit volume "void" generated by the surrounding rock loss within the volume domain of the actual three-dimensional construction gap to obtain a calculation formula for the lateral displacement of the surrounding rock caused by the three-dimensional construction gap of the TBM; Step (1) comprises the following steps: Establish a three-dimensional rectangular coordinate system, where the origin of the coordinate system and the x-axis and y-axis are all located on the horizontal surface, and the z-axis is vertically downward; assume that point F(x 0 ,y 0 ,z 0 ), the lateral displacements of any point P(x,y,z) in the deep surrounding rock along the x-axis and y-axis caused by the unit volume void are: Where: β is the main influence angle of the surrounding rock above the tunnel, and its value is determined by consulting geological survey data; Step (2) comprises the following steps: The three-dimensional spatial model of the steep tunnel is established, and it is agreed that the TBM excavating downward is positive and excavating upward is negative; the buried depth of the center of the tunnel face is h; the buried depth at the x coordinate on the tunnel axis is a non-constant value that varies with x and γ; F(x 0 ,y 0 ,z 0 ) at the buried depth h(x 0 ) is calculated as: h(x 0 )=h+x 0 tanγ The length of the TBM excavation along the steep slope construction path is l, and the three-dimensional construction gap generated by the TBM after excavation without support is V s , the calculation formula is: V s =ηπR 2 Where: R is the outer diameter of the TBM; η is the formation loss percentage; According to the uniform stratum movement mode, the radius r of the surrounding rock convergence deformation boundary is obtained, and the calculation formula is:

2. According to claim 1, a method for predicting lateral displacement of surrounding rock caused by steep slope TBM construction, Features Step (3) comprises the following steps: The unit volume "gap" obtained in step (1) is integrated in the volume domain of the three-dimensional construction gap in step (2), wherein the volume domain includes the space volume A enclosed by the TBM boundary ring along the tunnel axis for a distance of l and the space volume B enclosed by the surrounding rock convergence deformation boundary along the tunnel axis for a distance of l. The space volume A is subtracted from the space volume B to obtain the calculation formulas for the lateral displacement of the surrounding rock along the x-axis and the y-axis caused by the three-dimensional construction gap during the TBM excavation process, respectively:

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