JP2002047880A - Method of estimating displacement of facing peripheral part of tunnel, and method of determining prelining member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of easily and accurately estimating the displacement of a facing peripheral part of a tunnel at a low cost, and a method of determining a prelining member of the tunnel. SOLUTION: An equation for estimating the displacement of the facing peripheral part of the tunnel generated when the tunnel is excavated comprises an equation expressing a curve R based on a circular tunnel theoretical equation which is a dynamical theoretical equation, and an equation expressing a prediction curve P formed referring to an initial earth pressure release rate curve based on a finite element method analysis. A curve of the estimation equation is formed of the continuation of the curve R of the circular tunnel theoretical equation and the prediction curve P. Since the equation expressing the prediction curve P shows the displacement relatively accurately in a region where the displacement cannot be accurately computed by the dynamical theoretical equation, the estimation equation of the displacement becomes accurate over the whole region. The force applied to the prelining member of the tunnel from the ground is easily and accurately estimated using the estimation equation, so that the dimensions, shape and installed state of the prelining member can be easily and appropriately determined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for estimating a displacement around a face of a tunnel and a method for deciding a receiving member.

[0002]

2. Description of the Related Art Conventionally, in a tunnel construction, there is a prior construction method as shown in FIG. 8 as an auxiliary construction method for stabilizing a face and a tunnel wall surface. FIG. 8 is a longitudinal sectional view of the tunnel. In this pre-receiving method, first, a ring-supporting soil 104 is constructed on the tunnel wall surface 101 of the tunnel T, and then concrete is sprayed onto the lining concrete layer 106 having a predetermined thickness.
After that, a steel pipe 103 as a receiving member is inserted at a position behind the face 102 at a predetermined angle with respect to the tunnel axis and radially in the tunnel cross section toward the front of the face 102. I do. Subsequently, a hardening material is injected into the ground around the steel pipe 103 through a hole provided in the steel pipe 103, and thereafter, the tunnel T is dug. Then, the ground in front of the face 102 of the tunnel T and around the tip of the tunnel T is loosened and tends to be displaced toward the inner space side of the tunnel, but the force for displacing the ground is supported by the steel pipe 103, The front of the face 102 of the tunnel T and the wall surface 101 of the tunnel T are stabilized.

[0003] In the above-mentioned prior receiving method, the dimensions and arrangement of the steel pipe 103 are determined in the vicinity of the face of the tunnel T (the front of the face 102 and the periphery of the tip of the tunnel T are referred to as the face periphery). At the end of the tunnel T, it is assumed that a ground load corresponding to the size of the slack region acts as a dead load from above the steel pipe 103. It functions as a structure of a cantilever having a fixed end, and assumes that a supporting force is exhibited from its bending rigidity. First, after examining the rock quality of the ground around the face of the tunnel T, the size of the loose area corresponding to the shape of the tunnel and the shape of the tunnel, and the size of the soil cover were determined by model experiments and Estimated based on past construction results. The value obtained by multiplying the volume of the loose area by the unit volume weight of the ground is the force acting on the steel pipe 103.

[0004]

However, the method of estimating the loose volume around the face of the tunnel T is based on empirical estimation based on rock quality and conventional construction and model tests. Inaccurate. Accordingly, the force acting on the steel pipe 103 estimated from the loose volume becomes inaccurate, and therefore, the construction cost of the tunnel T is increased by using a steel pipe that is larger than the actually required steel pipe, or
There is a problem that the face 102 and the wall surface 101 of the tunnel T become unstable because a force from the ground cannot be supported by using a steel pipe smaller than an actually necessary steel pipe.

Therefore, in order to accurately grasp the force acting on the steel pipe 103, the displacement of the periphery of the face of the tunnel T is estimated by numerical analysis such as a finite element method. Although a method of calculating the acting force is also conceivable, it is necessary to create a model over the entire length of the tunnel T and perform a numerical analysis, and furthermore, in order to obtain an increment of displacement, an analysis is performed for each predetermined face traveling length in the tunnel traveling direction. Requires a great deal of labor and cost.

According to the results of the field behavior measurement of the steel pipe 103, it has been clarified that the supporting force exerted by the steel pipe is mainly induced not by the bending rigidity of the steel pipe but by the vertical rigidity in the axial direction of the steel pipe. Therefore, it can be said that the supporting force expression mechanism assuming the above-mentioned beam structure is inappropriate, and it is necessary to improve the cross-sectional performance of the steel pipe by considering the load load with bending rigidity,
There is a high possibility of overdesign.

Accordingly, an object of the present invention is to provide a method for easily and inexpensively estimating the displacement of the periphery of a face of a tunnel in spite of that, and a method for determining a precedent member of a tunnel using the method. It is in.

[0008]

In order to achieve the above object, a method for estimating the displacement of a portion around a face of a tunnel according to the present invention comprises: It is characterized by the following.

According to the method for determining a precedent member of a tunnel according to the present invention, the method is provided around a face of an excavated tunnel,
In the method for determining a front end member of a tunnel which stabilizes a face and a wall surface of the tunnel by supporting a force induced by the displacement of the ground, the method for estimating a displacement of a periphery of a face of the tunnel may be used to determine The present invention is characterized in that at least one of a size, a shape, a casting interval, and a casting angle of the receiving member is determined by obtaining a force acting on the receiving member.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments.

FIGS. 1 (a) and 1 (b) are curves of a displacement estimating equation according to the displacement estimating method of a portion around a face of a tunnel according to the present invention. It is a curve which shows the displacement distribution which arises. The vertical axis in FIG. 1A is the dimensionless displacement in the tunnel axis direction.
u ^* _z, and a positive sign indicates the direction in which the face moves. The vertical axis in FIG. 1 (b) indicates the dimensionless displacement u ^* _y in the vertical direction,
The negative sign is the direction toward the inside of the tunnel. FIG. 1 (a),
The horizontal axis in (b) is the tunnel radius a with the face position as the origin.
Shows the dimension z / a of the tunnel axis in the dimensionless direction. Figure 1
The curves (a) and (b) consist of a curve R and an expected curve P, and the two curves P and R are based on the following equations.

[0012]

(Equation 3)

Where u is the displacement of the ground in the radial direction of the tunnel, a is the radius of the tunnel, ν is the Poisson's ratio of the ground, E is the Young's modulus of the ground, P _{0 is} the ground pressure before tunnel excavation, and P _{i is the} tunnel excavation. Immediately after earth pressure, r: moving radius in polar coordinates with the origin at the center of the face of the tunnel cross section.

This equation (1) is obtained by the circular tunnel theory. In a circular cross section tunnel, the elastic displacement in the cross section direction of the tunnel is obtained from the difference in ground pressure before and after excavation of the tunnel. Function. First, the curve R is obtained as follows. First, for convenience, consider a circular tunnel indicated by a dotted line in FIG. 2 whose center coincides with the center position of the cutting face in the longitudinal direction, and polar coordinates (r, θ) having the origin at the center of the circular tunnel are introduced. Is the same as equation (1). This equation (1) And expand (Q × a / r) to Young's modulus, Poisson's ratio,
Expressing as a dimensionless displacement u ^* that does not depend on the initial ground pressure, and further transforming the coordinate system of this equation (1) into an orthogonal coordinate system of the tunnel axis direction and the vertical direction, u ^* is expressed by the following equation, respectively. Equation (2) and equation (3) are obtained.

[0015]

(Equation 4)

[0016]

(Equation 5)

Where u ^* _z : dimensionless displacement of the ground in the direction of the tunnel axis, u ^* _y : dimensionless displacement of the ground in the vertical direction, z: coordinate in the direction of the tunnel axis with the tunnel face as the origin, y: tunnel vertical coordinate as the origin wall of the top, a: tunnel radius, Q: the initial locations pressure release rate _{(1-p i / p 0} ).

Equation (2) is an equation representing a curve R indicating the displacement distribution in the tunnel axis direction of FIG. 1A, and equation (3) is
In the curve (b) showing the vertical displacement distribution of the ground, it is an equation representing the curve R in the region of 0 ≦ z.

On the other hand, in FIG. 1B, the curve in the region where z <0 is a curve P. The equation representing the curve P is an equation as shown in the following equations (4) and (5).

[0020]

(Equation 6)

[0021]

(Equation 7)

Where u ^* _y : dimensionless displacement of the ground in the vertical direction, z: coordinate in the direction of the tunnel axis with the origin at the tunnel face, y: vertical coordinate with the origin at the top of the tunnel wall, a: radius of the tunnel , E: base of natural logarithm.

Equations (4) and (5) are determined with reference to the curve shown in FIG. The curve in FIG. 3 is an initial ground pressure release rate curve obtained by modeling a process of excavating a tunnel having a circular cross section on the ground and a face thereof, and analyzing the model by a finite element method. Since this initial ground pressure release rate curve is obtained from the wall displacement occurrence rate based on the convergence displacement at a position sufficiently distant from the face of the above analysis result, there is a correlation with the ground displacement, and furthermore, this curve Estimation formula (3) created based on the value at z = 0 and the mechanical theoretical formula (1)
The values at z = 0 are assumed to be substantially equal, and this is connected to this estimation formula (3) to estimate the displacement of the ground at z <0. Also, since this curve converges to a substantially constant value at z <−4a, the equation in the region of z <−4a is: -4a ≦ z <
The formula is different from the region of 0.

In order to verify the accuracy of the estimation equation consisting of the above equations (2), (3), (4), and (5), FIG.
A comparison is made between the curves P and R shown in FIG. 4B and the curve shown in FIG.
The curve in FIG. 4 is a curve showing the displacement distribution when the tunnel is excavated in the vicinity of the face of the tunnel. The curve of the finite element method analysis using the same model as the case where the above-mentioned initial soil pressure release rate curve is obtained. The result. In addition, Q was set to 1/4 based on the analysis result. In FIG. 4, u ^* _z is a dimensionless displacement of the ground in the tunnel axis direction, and u ^* _y is a vertical dimensionless displacement of the ground. The curve R shown in FIG. 1A substantially matches the curve of u ^* _{z in} FIG. 4, and the curves R and P shown in FIG. 1B substantially match the curve of u ^* _{y in} FIG. . That is, the estimation formulas (2), (3), (4), and (5) can estimate the displacement around the face of the tunnel as accurately as the estimation by the finite element analysis. Finally, E, v, P ₀ of the ground to be excavated is obtained by measurement or the like, The u ^* Nizorezore u ^* _z, by substituting u ^* _y, displacement is estimated.

A method of determining the size, shape, and arrangement of the precedent member in the preceding method of the tunnel using this estimation formula will be described below.

FIG. 5 shows a tunnel excavation procedure in which a precedent member is determined by the displacement estimating method of the periphery of the face of the tunnel in the above embodiment in the tunnel construction using the precedent construction method as an auxiliary construction method at the time of tunnel excavation. It is a longitudinal cross-sectional view. First, when the face of the tunnel T is at the position K0, the steel pipe P0 as a receiving member is formed at a predetermined angle with respect to the tunnel axis, slightly behind the face K0 of the tunnel wall 2, and the face K0 is formed. Insert toward the front. Then, the lining concrete 3 is provided on the tunnel wall surface 2 up to the face K0, and the lining concrete 3 fixes the end of the steel pipe P0 on the tunnel side. Thereafter, the tunnel T is excavated by the unit excavation amount b, and the tunnel T is dug to the position of the face K1. Thus, the tunnel wall 2 slightly behind the face Kn
Steel pipe Pn is inserted into the lining concrete 3 to cut the face Kn.
After that, one cycle of tunnel excavation is completed by excavating the unit excavation amount b. FIG. 5 shows a state immediately after the steel pipe P5 is inserted into the tunnel wall 2 slightly behind the face K5 and the lining concrete 3 is extended to the face K5 after repeating the above-described cycle five times from the face K0. I have.

FIGS. 6 (a) and 6 (b) show 0.5 to 0.5 from K0 in FIG. 5 for the face K0 whose face length is 0 m.
It is the curve which showed the displacement distribution which arises in the ground of the steel pipe insertion direction position from the back of m. These curves are obtained by examining the ground displacement distribution in the direction in which the steel pipe is inserted and in the direction perpendicular thereto, and these distributions include the effects of the steel pipe being inserted into the ground. Absent. FIG. 6 (a)
The vertical axis indicates the non-dimensional ground displacement u ^* _s0 in the axial direction of the steel pipe P0, and the horizontal axis indicates the axial position s / a of the non-dimensional steel pipe P0 with the tunnel radius a. On the other hand, the vertical axis in FIG. 6B shows the dimensionless ground displacement u ^* _t0 in the direction perpendicular to the axis of the steel pipe P0, and the horizontal axis shows the dimensionless steel pipe P with the tunnel radius a as in FIG. Indicates the axial position s / a of P0. FIG. 6 (a), (b)
Curve shows that the steel pipe P0 is 0 ° with respect to the tunnel axis,
The displacements of the ground in the angular directions of 30 ° and 60 ° are respectively shown, and the coordinate system of the above estimation equations (2), (3), (4), and (5) is converted into a coordinate system along the steel pipe P0. It is calculated from the formula.

FIG. 6A shows the cumulative displacement from the unexcavated state of the ground to the face K0, which occurs in the direction of inserting the steel pipe P0 at a predetermined angle with respect to the tunnel axis. On the other hand, according to FIG. 6B, the cumulative displacement from the unexcavated state of the ground to the face K0, which occurs in a direction perpendicular to the direction in which the steel pipe P0 is inserted at a predetermined angle with respect to the tunnel axis, can be seen.

Next, the amount of change in ground displacement accompanying the progress of the face is determined. The displacement shown in FIG.
It is a cumulative displacement up to 0, but in the case of the precedent method, construction is generally started from a certain face position in the tunnel, and the axial force generated in the steel pipe is the change in ground displacement accompanying the progress of the face. This is because they are induced by the minute. FIG.
(A) and (b) are curves for estimating the amount of change in ground displacement in the axial direction of the steel pipe P0 when the excavation of the tunnel T proceeds from the face K1 to the face K5 on the ground at the position where the steel pipe P0 is arranged. . The vertical axis in FIGS. 7 (a) and 7 (b) is the dimensionless displacement change amount Δu ^* _sn.
From 0 to K1 (n = 1), K3 (n = 3), and K5 (n
= 5) indicates the dimensionless displacement change amount that occurs at the position of the steel pipe P0 when the process proceeds to (5). On the other hand, FIG.
The horizontal axis in (b) is the dimensionless steel pipe P with the tunnel radius a.
0 is the axial position s / a. The curve in FIG. 7A shows the dimensionless displacement change amount of the ground in the steel pipe axis direction when the steel pipe P0 is arranged at 20 ° to the tunnel axis, and FIG. 7B shows the steel pipe P0. Shows the dimensionless displacement change amount in the steel pipe axis direction of the ground when the ground is arranged at 30 ° to the tunnel axis. The curves in FIGS. 7A and 7B are obtained by calculating the travel length (n) of one face from the equation representing the curve in FIG.
= 1) is 1 m and the tunnel radius is 5 m. These curves were obtained by examining the distribution of the change in ground displacement in the direction in which the steel pipe was inserted.
These distributions do not include the effects of inserting steel pipes into the ground. From the amount of change in the displacement, a force acting on the steel pipe P0 in the axial direction from the ground can be obtained using, for example, a shear coefficient between the ground and the steel pipe P0. In this way, the force acting on the steel pipe P0 is accurately determined, and the dimensions and thickness of the steel pipe that can withstand the force are determined. Then, the size and type of the steel pipe P0 can be appropriately determined, and a steel pipe larger than the actually required dimension is selected to increase the material cost, or the steel pipe P0 smaller than the actually required dimension is selected. There is no danger that the ground support will be insufficient by selecting.

According to the curve of FIG. 7 (a), when the excavation of the tunnel proceeds from the cutting face K1 to the cutting face K5, the amount of negative displacement change increases in the ground at a position making an angle of 20 ° with the tunnel axis. As the force toward the tunnel side end of the steel pipe P0 increases,
The positive displacement change amount increases, and the force toward the insertion side end of the steel pipe P0 also increases. Further, the area where the axial force acts on the steel pipe P0 also increases. Further, according to the curve in FIG. 7B, when the steel pipe P0 is arranged at 30 ° to the tunnel axis, when the excavation of the tunnel proceeds to the face K5, FIG.
As compared with the case where the steel pipe P0 is arranged at 20 ° in (a), particularly, the amount of negative displacement change, that is, the force toward the tunnel side end of the steel pipe P0 increases, and the area where the axial force acts on the steel pipe P0 is also increased. Increase. That is, when the excavation of the tunnel proceeds from the cutting face K1 to K5, an area where the ground is loosened in the ground around the tunnel expands, and as a result, a force acting on the steel pipe P0 toward the tunnel side increases. When the arrangement angle of the steel pipe P0 with respect to the tunnel axis is increased, the area where the ground is loosened further expands, and as a result, the force acting on the steel pipe P0 toward the tunnel side further increases.

Using the curves shown in FIGS. 7A and 7B, the force acting when the excavation of the tunnel T proceeds on the steel pipe P0 arranged at a predetermined angle with respect to the tunnel axis. It can be estimated accurately. Therefore, if the length and dimensions of the steel pipe P0 are selected so as to sufficiently support the above-mentioned force, it is possible to select the minimum necessary steel pipe P0, so that the material cost of the receiving member becomes economical. Moreover, the tunnel wall surface and the face can be stabilized.

Further, by using the method for estimating the displacement around the face of the tunnel according to the above-described embodiment, the lining member of the tunnel can be made thinner. That is, when the arrangement angle of the receiving member is 20 ° with respect to the tunnel axis, the force acting in the axial direction of the steel pipe P0 from the ground is applied to the tunnel side end using the ground displacement change curve of FIG. The length of the steel pipe P0 can be determined so as to be substantially balanced in both the direction and the insertion-side end direction. For example, the length of the steel pipe P0 is s /
When a = 2.0, when the excavation position of the tunnel is at the cutting face K5, the amount of change in the displacement of the ground in the axial direction of the steel pipe P0 is substantially equal in both the direction toward the tunnel side and the direction toward the insertion side. Moreover, when the excavation of the tunnel proceeds to the cutting face K1 and the cutting face K3, in each case, the amount of change in the axial displacement of the ground in the steel pipe P0 is larger in the insertion side end direction than in the tunnel side end direction. Therefore, the steel pipe P
As for the force acting on zero, the insertion side end direction always exceeds the tunnel side end direction. Therefore, almost no force acts on the steel pipe P0 in the direction of the tunnel side end.
It is not necessary to firmly fix and support the tunnel side end portion with the lining concrete 3. Therefore, the lining concrete 3 can be made thinner, and the tunnel construction cost is reduced.

In the above-described embodiment, the description has been given of the case where the force acting on the pre-receiving member is obtained by using the change amount of the displacement of the pre-receiving member in the insertion direction. The force acting on the steel pipe P0 in a direction perpendicular to the axis of the steel pipe P0 from the ground may be obtained from the change in the displacement using the change in the displacement in the perpendicular direction and the elasticity of the steel pipe P0 from the change in the displacement. May be used in combination. Further, in the excavation of the tunnel in which the precedent member is determined by the displacement estimating method of the periphery of the face of the tunnel in the above-described embodiment, a round steel pipe is used as the precedent member. It may be something.

The method for estimating the displacement around the face of a tunnel and the method for deciding the receiving member according to the present invention can be applied not only to tunnel construction but also to construction of underground cavities for oil storage, for example.

[0035]

As is apparent from the above description, the method for estimating the displacement of the periphery of a tunnel face according to the first aspect of the present invention calculates the displacement of the periphery of the tunnel face caused by excavation of the tunnel by a predetermined estimation formula. Since it is obtained, the displacement around the face of the tunnel can be easily estimated.

According to a second aspect of the present invention, there is provided a method for estimating a displacement of a portion around a face of a tunnel according to the first aspect, wherein the estimation formula comprises at least one dynamic theoretical formula and Since it is composed of the equation representing the determined expected curve, the equation representing the expected curve represents the displacement relatively accurately for the area that does not match the actual value when the above-mentioned dynamic theoretical equation is applied. The displacement can be accurately estimated.

According to a third aspect of the present invention, there is provided a method for estimating the displacement of a portion around a face of a tunnel according to the second aspect of the present invention, wherein the above-mentioned mechanical theoretical formula comprises an initial ground pressure of the tunnel and a tunnel excavation. Since the mechanical theory using the following ground pressure, ground Poisson's ratio, and ground Young's modulus as parameters, the displacement of the tunnel can be accurately obtained.

According to a fourth aspect of the present invention, there is provided the method for estimating the displacement of the periphery of a face of a tunnel according to the second or third aspect. Since the equation is predetermined with reference to the finite element method analysis solution of the displacement of the portion, the displacement can be accurately and easily estimated even in a region where the displacement cannot be calculated accurately by the above-mentioned mechanical theoretical formula.

According to a fifth aspect of the present invention, there is provided a method for estimating a displacement around a face of a tunnel according to the second or third aspect. Since the initial pressure release rate obtained from the displacement around the face of the tunnel, the influence of the initial pressure release rate can be accurately expressed, and the displacement can be calculated even in the area where the displacement cannot be calculated accurately by the above-mentioned mechanical theoretical formula. Can be accurately and easily estimated.

According to a sixth aspect of the present invention, there is provided a method for estimating a displacement around a face of a tunnel according to the second or third aspect. This is a curve obtained by referring to the initial ground pressure release rate obtained from the finite element method analysis solution of the displacement of the ground, and accurately represents the effect of the initial ground pressure release rate on the displacement without actually measuring it. In addition, since the displacement can be accurately obtained even in a region that cannot be accurately obtained by the above-mentioned mechanical theoretical formula, the above-mentioned estimation formula becomes accurate.

According to a seventh aspect of the present invention, there is provided a method for determining a front face of a tunnel, wherein the front face of the tunnel is installed around a face of an excavated tunnel to support a force induced by displacement of the ground. And a method for determining a receiving member of a tunnel for stabilizing a wall surface, wherein a force acting on the receiving member is easily and relatively accurately obtained by using the displacement estimating method of a portion around a face of a tunnel according to claims 1 to 6. Therefore, it is possible to easily and appropriately determine the size, shape, installation state, and the like of the receiving member.

According to a eighth aspect of the present invention, there is provided a method for determining a precedent member of a tunnel according to the seventh aspect, wherein the precedent member is provided with a shaft of the precedent member by displacement of the ground. Since the force acting in the direction is supported by the lining member fixing the end of the front receiving member on the side of the tunnel, the displacement of the ground can be estimated using the displacement estimating method of the periphery of the face of the tunnel according to claims 1 to 6. It is possible to easily and accurately determine the size, shape, installation state, and the like of the above-mentioned receiving member in a simple and appropriate manner. Therefore, the number of the above-mentioned receiving members can be minimized, and the material cost of the receiving members can be reduced.

According to a ninth aspect of the present invention, there is provided a method for determining a tunnel receiving member according to a seventh aspect of the present invention. Since the force acting in both directions has a length, an installation angle, and a dimension that balance the forces, the ground can be supported by only the front receiving member, and the periphery of the face of the tunnel can be stabilized. Therefore, it is not necessary to firmly fix the tunnel-side end of the receiving member, so that tunnel construction costs can be reduced.

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) are diagrams showing curves of an estimation formula by a displacement estimation method of a portion around a face of a tunnel according to the present invention.

FIG. 2 is a diagram showing a coordinate system representing an estimation formula in a tunnel having a circular cross section.

FIG. 3 is an initial ground pressure release rate curve obtained by finite element analysis when a tunnel having a circular cross section is excavated in the ground.

FIG. 4 is a diagram showing displacement of a portion around a face of a tunnel by finite element analysis.

FIG. 5 is a diagram showing a tunnel excavation procedure using a receiving member determined by the displacement estimating method of a portion around a face of the tunnel shown in FIG. 1;

FIGS. 6 (a) and 6 (b) show the estimation of the displacement of the position of the receiving member when the tunnel is excavated with respect to the receiving member disposed at the approximate face position of the tunnel. It is a curve shown in the coordinate system of the receiving member.

FIGS. 7 (a) and 7 (b) show displacement changes in the position of the front receiving member when the excavation of the tunnel advances and the front face advances, with respect to the front receiving member arranged at the approximate face position of the tunnel. It is the curve which estimated the amount.

8 (a) and 8 (b) are views showing a pre-receiving method of a tunnel using a pre-receiving member determined by a conventional displacement estimating method for a portion around a face of a tunnel.

[Explanation of symbols]

 K0, K1, K2, K3, K4, K5 Face P0, P1, P2, P3, P4, P5 Steel pipe T Tunnel 2 Tunnel wall 3 Lining concrete

Claims (9)

[Claims] 1. A displacement estimating method for a section around a face of a tunnel, wherein a displacement generated by excavation of the section around the face of the tunnel is obtained by a predetermined estimation formula. 2. The displacement estimating method according to claim 1, wherein said estimating formula is created based on a dynamic theoretical formula. Estimation method. 3. A method according to claim 2, wherein said dynamic theoretical formula is the following formula assuming a circular tunnel and an isotropic initial ground pressure. Method for estimating the displacement around the face of the face. (Equation 1) Where u is the displacement of the ground in the radial direction of the tunnel, a is the radius of the tunnel, ν is the Poisson's ratio of the ground, E is the Young's modulus of the ground, P
_0: tunneling previous ground pressure, P _i: immediately after the tunnel excavation ground pressure, r: polar radius vector having an origin of the tunnel cross section Face center. 4. The displacement estimating method of a portion around a face of a tunnel according to claim 2 or 3, wherein the estimating formula is an equation determined with reference to a finite element method analytical solution of displacement of a portion around a face of the tunnel. A method for estimating a displacement around a face of a tunnel. 5. A method according to claim 2, wherein one of the elements of the estimation formula is an initial ground pressure release rate. Displacement estimation method. 6. A method according to claim 2, wherein one of said estimating formulas is represented by the following equation: Displacement estimation method. (Equation 2) Where u ^* _y : the dimensionless displacement of the ground in the vertical direction, z: the coordinate of the tunnel axis with the origin at the tunnel face, y: the vertical coordinate with the origin of the wall at the top of the tunnel, a: the radius of the tunnel, e: The base of the natural logarithm. 7. Determining a pre-loaded member of the tunnel which is installed around the face of the excavated tunnel to support the force induced by the displacement of the ground and to stabilize the face and wall surface of the tunnel. A method for estimating a force acting on the receiving member by using a displacement estimating method of a portion around a face of a tunnel according to claims 1 to 6, and determining a size, a shape, a driving interval and a driving angle of the receiving member. A method for determining a preceding member of a tunnel, wherein at least one is determined. 8. The method for determining a receiving member of a tunnel according to claim 7, wherein the receiving member applies a force acting in an axial direction of the receiving member by an increase in displacement of the ground to a tunnel of the receiving member. A method for deciding a preceding bearing member of a tunnel, wherein the side end portion is supported by a lining member that fixes the side end portion. 9. The method according to claim 7, wherein the force acting in both the axial direction of the support member induced by the displacement of the ground is substantially balanced. A method for determining a preceding bearing member of a tunnel, characterized by having a length, an installation angle and dimensions.