US 12,163,429 B1 · Method of buffer layer with critical deformation of tunnel initial support as control target

Abstract

The present disclosure relates to the technical field of tunnel construction, in particular to a design method of a buffer layer with critical deformation of a tunnel initial support as a control target. The method includes the following steps: (1) establishing a mechanical model and calculating an ultimate bearing capacity of the tunnel initial support during critical damage based on a cusp catastrophe theory; (2) determining a critical deformation value of the tunnel initial support under the ultimate bearing capacity; (3) establishing a yielding control target of a tunnel buffer layer; (4) determining a performance index of the buffer layer according to the control target, and calculating corresponding index parameters. Compared with the prior art, the method has the following beneficial effects. The method aims to put forward the critical deformation value of the tunnel initial support under the ultimate bearing capacity, obtain an optimal yielding design parameters of the buffer layer by taking a compression and load transfer mode of the tunnel buffer layer as a link, and give a calculation method.

A method of designing and constructing a tunnel with a buffer layer having a tunnel initial support with critical deformation characteristics, the critical deformation characteristics of the tunnel initial support being a control target, wherein the method comprises the following steps:

(1) establishing a mechanical model, obtaining a function expression in a state of critical catastrophe instability of the tunnel initial support in combination with a cusp catastrophe theory, and considering mechanical and design parameters of the tunnel initial support to obtain an ultimate bearing capacity of the tunnel initial support;
(2) determining a critical deformation value of the tunnel initial support under the ultimate bearing capacity;
(3) establishing a yielding control target of a tunnel buffer layer;
(4) determining a performance index of the buffer layer according to the control target, and calculating corresponding index parameters, wherein
the function expression in the state of critical catastrophe instability of the tunnel initial support is calculated as follows:
1) a total system potential energy V(x) is a sum of bending strain energy V1, system potential energy variation V2 and external load work V3 of the tunnel initial support:
V(x)=V1+V2+V3;
2) the bending strain energy V1, the system potential energy variation V2 and the external load work V3 of the tunnel initial support are calculated, respectively;
3) the calculation relationship among the bending strain energy, the system potential energy variation and the external load work is substituted into an expression of the total system potential energy to obtain a potential function V:
V=V1−V2−V3
=
E
⁢
I
⁢
π
6
8
⁢
L
5
⁢
ω
4
+
π
2
4
⁢
L
[
4
⁢
EI
⁢
π
2
L
2
-
(
γ
⁢
H
⁢
cos
⁢
α
+
q
)
⁢
L
]
⁢
ω
2
-
1
2
⁢
tx
)
⁢
ω
⁢
γ
⁢
HL
⁢
cos
⁢
α
;
where α is an inclination angle, γ is a bulk density of tunnel initial support material, ω is a midpoint deflection of the initial support interception interval, H is a thickness of the initial support, L is a length, E is an elasticity modulus of initial support material, q is an overlying load of the tunnel, and/is a moment of inertia of an initial support section;
4) based on the cusp catastrophe theory, a standard form and a bifurcation set equation of the potential function of a tunnel initial support model are obtained;
5) when a control variable satisfies the bifurcation set equation, the critical catastrophe instability of the tunnel initial support occurs, and the function expression in the state of critical catastrophe instability of the tunnel initial support is obtained:
[
E
⁢
H
3
⁢
π
2
3
⁢
L
2
-
(
γ
⁢
H
⁢
cos
⁢
α
+
q
)
⁢
L
]
3
+
9
⁢
E
⁢
γ
2
⁢
H
5
⁢
cos
2
⁢
α
1
⁢
6
=
0
;
[
E
⁢
H
3
⁢
π
2
3
⁢
L
2
-
(
γ
⁢
H
⁢
cos
⁢
α
+
q
)
⁢
L
≤
0
;
and
constructing the tunnel with the buffer layer in accordance with the critical deformation characteristics of the tunnel initial support as determined.

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Method of buffer layer with critical deformation of tunnel initial support as control target

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Method of buffer layer with critical deformation of tunnel initial support as control target

Life of this patent

Abstract

Claims6