Method for calculating earth pressure load on a tunnel

Abstract

A method for calculating an earth pressure load on a tunnel includes the following steps: (1) taking interaction between external soil and a tunnel structure in an actual operation condition as an earth pressure load acting on the tunnel structure; (2) establishing a physical model for the tunnel structure; (3) designing, on the basis of the physical model for the tunnel structure, a plurality of structural loads in different operation conditions to obtain a plurality of different structural deformations; and (4) drawing an inference according Betti's theorem, and establishing a physical model for an original structure, such that a load on the original structure, namely an earth pressure load on the tunnel, can be directly calculated according to a load-deformation relationship of the physical model and deformation of the original structure. The above method can determine distribution and size of an actual earth pressure load on a tunnel.

Claims

1. A method for calculating earth pressure load on a tunnel, characterized in comprising the following steps: (1) regarding the interaction between the external soil and the tunnel as the earth pressure load on the tunnel structure, under the action of the soil load [X].sub.n*1, the deformation of the tunnel structure [W].sub.n*1 is formed, where n is the equal parts number of the tube segments, [X].sub.n*1 is the earth pressure load, expressed as a matrix of n rows and 1 column; [W].sub.n*1 is the deformation of the segment, expressed as a matrix of n rows and 1 column; (2) establishing physical model of the tunnel structure; (3) based on said physical model of the tunnel structure, designing n groups of different loads to obtain n groups of different deformation values, and expressed in matrix form as the load matrix [s].sub.n*n, and the structural deformation matrix [v].sub.n*n; (4) based on Betty's theorem theory, constructing the equation [s].sub.n*n*[X].sub.n*1=[V].sub.n*n*[W].sub.n*1; (5) solving to get [Xi].sub.n*1, which is the earth pressure load on the tunnel; and (6) evaluating structural performance and applying measures to control tunnel diseases based on the earth pressure load; wherein in the step (1), the deformation of the tunnel structure is a whole circumferential deformation or a whole spatial deformation, and according to the physical model in the step (2), in case the physical model is a plane model, the deformation of the tunnel is a whole circumferential deformation; in case the tunnel structure is a three-dimensional model, the deformation of the tunnel is a whole spatial deformation; and wherein in the step (1), the deformation of tunnel structure is acquired by using a three-dimensional laser scanner, through detecting and acquiring the point cloud of the surface of the tunnel structure, to establish a tunnel structure model based on the point cloud, the tunnel structure deformation value [W].sub.n*1 can be obtained.

2. The method for calculating earth pressure load on a tunnel according to claim 1, wherein the earth pressure load in the step (1) is an arbitrary direction load, including a surface force perpendicular to the segment or a surface force not perpendicular to the segment.

3. The method for calculating earth pressure load on a tunnel according to claim 1, wherein the earth pressure load in the step (1) is a non-uniform distributed load, which is divided into n groups of loads with different values on the surface of the tunnel, and when the tunnel is a shield segment assembly type tunnel, n is the number of segments; when the tunnel is a pouring in site type tunnel, the value of n is determined according to the structural characteristics.

4. The method for calculating earth pressure load on a tunnel according to claim 1, wherein in the step (1), the deformation of the tunnel structure is a whole circumferential deformation or a whole spatial deformation, and according to the physical model in the step (2), in case the physical model is a plane model, the deformation of the tunnel is a whole circumferential deformation; in case the tunnel structure is a three-dimensional model, the deformation of the tunnel is a whole spatial deformation.

5. The method for calculating earth pressure load on a tunnel according to claim 1, wherein the matrix composed of a plurality of load-deformation relationships in the step (3) is a non-singular matrix.

6. The method for calculating earth pressure load on a tunnel according to claim 1, wherein the matrix dimension in the step (3) is greater than or equal to the number of loads in the step (1).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a diagram showing the load-deformation relationship of a tunnel structure in the actual environment of the present invention;

(2) FIG. 2 is a structural load-deformation relationship diagram of a physical model of a tunnel structure according to the present invention;

(3) FIG. 3 is a three-dimensional finite element tunnel structure model in an embodiment of the present invention;

(4) FIG. 4 is a schematic diagram of structural deformation obtained under a real working condition by using a three-dimensional laser scanning method.

(5) FIG. 5 is a calculated value of the tunnel earth pressure of the method of the present invention, wherein FIG. 5a shows the tunnel earth pressure distribution trend, and FIG. 5b shows the tunnel earth pressure value.

DETAILED DESCRIPTION OF THE INVENTION

(6) The present invention is further described below by combining with the drawings and embodiment.

Embodiment

(7) A method for calculating earth pressure load on a tunnel, comprising the following steps:

(8) (1) Expressing the relationship between the earth pressure load and the structural deformation of tunnel under real working conditions.

(9) As shown in FIG. 1, the earth load, including foundation resistance and earth pressure, is regarded as the full space structural load outside the tunnel. All loads are differentiated into n unknown forces {X.sub.i}, resulting in corresponding full-space shift {W.sub.i}, where i is the position of the tunnel location i, that is, {X.sub.i} is the load at position i and {W.sub.i} is the shift at position i. The full-space loads under real working conditions are expressed by [X].sub.n*1, and the full-space deformation under real working conditions is expressed by [W].sub.n*1.

(10) (2) Expressing the relationship between earth pressure load and structural deformation under design conditions.

(11) A three-dimensional finite element model of tunnel structure (shown in FIG. 3) is established to reflect the load-deformation relationship more truthfully. The n-group load combination {S.sub.ij} is designed and the n-group structural deformation {V.sub.ij} is obtained, where is the position of the tunnel location i, and j is the design condition of group j. That is to say, {S.sub.ij} is the load at position i under load condition of group j, and {V.sub.ij} is the deformation at position i under load condition of group j. The full-space load under design condition is expressed by [s].sub.n*n, and the full-space deformation under design condition is expressed by [v].sub.n*n.

(12) (3) FIG. 4 shows the full-space structural deformation [W].sub.n*1 under real working conditions acquired by a three-dimensional laser scanning method.

(13) (4) Constructing the equation [S.sub.ij].sub.n*n*[x.sub.i].sub.n*1[V.sub.ij].sub.n*n*[W.sub.i].sub.n*1 based on Betty's theorem.

(14) (5) The solution of [X.sub.i].sub.n*1 is the earth pressure load of tunnel.

(15) Making formula in the step (4) full rank, the load [q].sub.n*1 can be obtained by solving the formula by matrix method. The earth pressure load of the tunnel can be obtained. As shown in FIG. 5, the method of the invention calculates the earth pressure. FIG. 5a is the trend of soil pressure distribution in tunnel, and FIG. 5b is the numerical value of soil pressure in tunnel.