CN105401954A - Tunnel anti-expansion support design method - Google Patents

Abstract

The invention discloses a tunnel anti-expansion support design method. The method comprises the following steps that firstly, the lateral confinement free expansion test and the expansion force and time test are carried out; secondly, according to a test result, parameters of an expansion constitutive equation containing the time effect are obtained; thirdly, according to the expansion constitutive equation containing the time effect, a relation equation of tunnel expansion deformation and support anti-expansion force is established; fourthly, under the boundary condition that the support force is equal to zero, the expansion deformation of the tunnel construction period is worked out, expansion deformation is considered in the reserved deformation design based on the calculation result, and the problems of instability and beyond limit caused by expansibility in the construction period are effectively solved; and fifthly, under the boundary condition of displacement restraint, the expansion force borne by a tunnel running period secondary lining is worked out, the anti-hydrostatic pressure design is added in the secondary lining, the anti-hydrostatic pressure value is not smaller than the maximum expansion force value in the running period, and the problem of stability in the running period is effectively solved.

Description

The anti-expansion support design method in a kind of tunnel

Technical field

The present invention relates to the anti-expansion support design method in a kind of tunnel.

Background technology

In underground geotechnical engineering is built, particularly for construction of tunnel, the dilatancy of expansive rock can produce the bulbs of pressure to structure wherein, and have a strong impact on the stability of engineering, the harm of expansive rock dilatancy to tunnel is mainly reflected in:

1) construction period, expansion can cause the unstability of preliminary bracing and invade limit.

2) run the phase, expansion force can be applied to two and be lining with, and causes the destruction of two linings, affects the long-time stability in tunnel.

The anti-expansion support design method in existing tunnel, how based on engineering experience, the inadequate economical rationality of the design parameters provided, do not have set of system, science, can the method for designing of accurate quantitative analysis.

Summary of the invention

For above shortcomings in prior art, the invention provides a kind of can Accurate Prediction expansion deformation allowance size and the anti-expansion support design method in tunnel of anti-expansion force size can be served as a contrast by Accurate Prediction two.

In order to solve the problems of the technologies described above, present invention employs following technical scheme:

The anti-expansion support design method in a kind of tunnel, the method comprises the steps:

1) expansion test: get core to the tunnel surrounding that will simulate, is processed into diameter 61mm height 20mm patty test specimen;

1.1) side limit free wxpansion test: use consolidometer to test, vaseline oil is coated at the test specimen ring inwall of consolidometer water box, again test specimen is put into test specimen ring, place thin filter paper and porous disc at test specimen upper and lower side, fixed metal plate is placed at top, and installs vertical dial gauge, slowly to water filling in water box, the water surface exceeds test specimen 5mm, adopts computer sampling, record dilatancy and the relation of time;

1.2) expansion force and time test: choose multiple test specimen, adopt step 1.1) in method, allow its free wxpansion, after expanding into different time, pressurization, pushes back distortion, when test specimen is pressed onto zero distortion, required pressure is the bulbs of pressure, sets up the relation of the bulbs of pressure and time;

2) according to the following expansion constitutive equation containing time effect, matching is carried out to expansion test result;

2.1) parameter of rock expansion strain-equation of time is obtained by side limit free wxpansion test;

${\mathrm{\ϵ}}_t=\frac{m}{1+{\mathrm{at}}^{-b}}---\left(1\right)$

In formula, t is Bulking Time; ε _tfor t expansion strain; M, a and b are rock expansion strain-equation of time parameter, wherein m>0, b>0; Model parameter, is obtained by the result of side limit free wxpansion test;

2.2) test by expansion force and time the parameter obtaining rock expansion stress-equation of time, equation is as follows:

σ _t＝c(1-e ^-dt)(2)

In formula, t is Bulking Time, and e is natural constant, σ _tfor t swelling stress, c>0, d>0 are material characteristic parameter, are obtained by test matching;

2.3) containing the expansion constitutive equation of time effect:

$\mathrm{\ϵ}=\frac{m{\[\mathrm{\σ}-c(1-e^{-dt})\]}^2}{c^2(1+{\mathrm{at}}^{-b}){(1-e^{-dt})}^2}---\left(3\right)$

A, b, c, d and m of simulating before are substituted into (3) formula must containing the expansion constitutive model of time effect;

3) according to the expansion constitutive model of equation (3) containing time effect, tunnel dilatancy is set up and supporting anti-expansion force relation equation is as follows:

$U=kD\frac{m{\[p-c(1-e^{-dt})\]}^2}{c^2(1+{\mathrm{at}}^{-b}){(1-e^{-dt})}^2}---\left(4\right)$

In formula, U is dilatancy; P is the anti-expansion force of supporting; K is the coefficient relevant with tunnel geology condition; D is the tunnel excavation radius of influence; A, b, c and d are coefficient, are obtained by test;

3.1) constructing tunnel phase anti-inflated design: according to dilatancy and the anti-expansion force relation of supporting, P=0 and t=t ₀substitution formula (4) can calculate U=U ₀; Then in the design of tunnel deformation allowance, additionally consider U ₀thick dilatancy, reaches construction period anti-expansion effect; Above-mentioned t=t ₀for preliminary bracing in actual condition and two serves as a contrast interval time;

3.2) tunnel operation phase anti-inflated design: according to dilatancy and the anti-expansion force relation of supporting, t=t ₁and U=U ₁substitution formula (4) can calculate P=P ₁; Be then the opposing bulbs of pressure, in tunnel double-lining design, extra consideration is not less than P ₁hydrostatic pressure resistant power, reach operation phase anti-expansion effect; Above-mentioned t=t ₁for the tunnel service time limit, U=U ₁for the country rock dilatancy amount of construction period.

Technique effect of the present invention is: according to the dilatancy set up and the anti-expansion force relation equation of supporting, calculate constructing tunnel phase country rock dilatancy amount and the anti-expansion force born of two linings, based on result of calculation, consider dilatancy in being designed by deformation allowance, effectively solve unstability that the construction period causes by dilatancy, invade limit problem; By increasing the design of hydrostatic pressure resistant power in two linings are anti-, and make the value of hydrostatic pressure equal the value of maximum swelling power, and then effectively solve operation phase stability problem.

Accompanying drawing explanation

Fig. 1 is the modelling effect figure obtained by side limit free wxpansion test;

Fig. 2 tests by expansion force and time the modelling effect figure obtained;

Fig. 3 is the expansion constitutive model design sketch containing time effect.

Detailed description of the invention

Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail.

The anti-expansion support design method in a kind of tunnel, the method comprises the steps:

1) expansion test: get core to the tunnel surrounding that will simulate, is processed into diameter 61mm height 20mm patty test specimen;

1.1) side limit free wxpansion test: use consolidometer to test, vaseline oil is coated at the test specimen ring inwall of consolidometer water box, again test specimen is put into test specimen ring, place thin filter paper and porous disc at test specimen upper and lower side, fixed metal plate is placed at top, and installs vertical dial gauge, slowly to water filling in water box, the water surface exceeds test specimen 5mm, adopts computer sampling, record dilatancy and the relation of time;

1.2) expansion force and time test: choose multiple test specimen, adopt step 1.1) in method, allow its free wxpansion, after expanding into different time, pressurization, pushes back distortion, when test specimen is pressed onto zero distortion, required pressure is the bulbs of pressure, sets up the relation of the bulbs of pressure and time.

2) according to the following expansion constitutive equation containing time effect, matching is carried out to expansion test result;

2.1) parameter of rock expansion strain-equation of time is obtained by side limit free wxpansion test;

${\mathrm{\ϵ}}_t=\frac{m}{1+{\mathrm{at}}^{-b}}---\left(1\right)$

In formula, t is Bulking Time; ε _tfor t expansion strain; M, a and b are rock expansion strain-equation of time parameter, wherein m>0, b>0; Model parameter, obtained by the result of side limit free wxpansion test, modelling effect is as shown in Figure 1;

2.2) test by expansion force and time the parameter obtaining rock expansion stress-equation of time, equation is as follows:

σ _t＝c(1-e ^-dt)(2)

In formula, t is Bulking Time, and e is natural constant, σ _tfor t swelling stress, c>0, d>0 are material characteristic parameter, and obtained by test matching, modelling effect as shown in Figure 2;

2.3) containing the expansion constitutive equation of time effect:

$\mathrm{\ϵ}=\frac{m{\[\mathrm{\σ}-c(1-e^{-dt})\]}^2}{c^2(1+{\mathrm{at}}^{-b}){(1-e^{-dt})}^2}---\left(3\right)$

A, b, c, d and m of simulating before are substituted into (3) formula must containing the expansion constitutive model of time effect, and modelling effect as shown in Figure 3.

3) according to the expansion constitutive model of equation (3) containing time effect, tunnel dilatancy is set up and supporting anti-expansion force relation equation is as follows:

$U=kD\frac{m{\[p-c(1-e^{-dt})\]}^2}{c^2(1+{\mathrm{at}}^{-b}){(1-e^{-dt})}^2}---\left(4\right)$

In formula, U is dilatancy; P is the anti-expansion force of supporting; K is the coefficient relevant with tunnel geology condition; D is the tunnel excavation radius of influence; A, b, c and d are coefficient, are obtained by test;

3.1) constructing tunnel phase anti-inflated design: according to dilatancy and the anti-expansion force relation of supporting, P=0 and t=t ₀substitution formula (4) can calculate U=U ₀; Then in the design of tunnel deformation allowance, additionally consider U ₀thick dilatancy, reaches construction period anti-expansion effect.Above-mentioned t=t ₀for preliminary bracing in actual condition and two serves as a contrast interval time.

3.2) tunnel operation phase anti-inflated design: according to dilatancy and the anti-expansion force relation of supporting, t=t ₁and U=U ₁substitution formula (4) can calculate P=P ₁; Be then the opposing bulbs of pressure, in tunnel double-lining design, extra consideration is not less than P ₁hydrostatic pressure resistant power, reach operation phase anti-expansion effect.Above-mentioned t=t ₁for the tunnel service time limit, U=U ₁for the country rock dilatancy amount of construction period.

What finally illustrate is, above embodiment is only in order to illustrate technical scheme of the present invention and unrestricted, although with reference to preferred embodiment to invention has been detailed description, those of ordinary skill in the art is to be understood that, can modify to technical scheme of the present invention or equivalent replacement, and not departing from aim and the scope of technical solution of the present invention, it all should be encompassed in the middle of right of the present invention.

Claims (1)

1. the anti-expansion support design method in tunnel, it is characterized in that, the method comprises the steps:

1) expansion test: get core to the country rock of the tunnel expansive rock section that will build, is processed into diameter 61mm height 20mm patty test specimen;

1.1) side limit free wxpansion test: use consolidometer to test, vaseline oil is coated at the test specimen ring inwall of consolidometer water box, again test specimen is put into test specimen ring, place thin filter paper and porous disc at test specimen upper and lower side, fixed metal plate is placed at top, and installs vertical dial gauge, slowly to water filling in water box, the water surface exceeds test specimen 5mm, adopts computer sampling, record dilatancy and time;

1.2) expansion force and time test: choose multiple test specimen, adopt step 1.1) in method, allow its free wxpansion, after expanding into different time, pressurization, distortion is pushed back, and when test specimen is pressed onto zero distortion, required pressure is the maximum swelling pressure under this Bulking Time, sets up the relation of maximum swelling pressure and Bulking Time;

2) according to the following expansion constitutive equation containing time effect, matching is carried out to expansion test result;

2.1) parameter of rock expansion strain-equation of time is obtained by side limit free wxpansion test;

${\mathrm{\ϵ}}_t=\frac{m}{1+{\mathrm{at}}^{-b}}---\left(1\right)$

In formula, t is Bulking Time; ε _tfor t expansion strain; M, a and b are rock expansion strain-equation of time parameter, wherein m>0, b>0; Model parameter, is obtained by the result of side limit free wxpansion test;

2.2) test by expansion force and time the parameter obtaining rock expansion stress-equation of time, equation is as follows:

σ _t＝c(1-e ^-dt)(2)

In formula, t is Bulking Time, and e is natural constant, σ _tfor t swelling stress, c>0, d>0 are material characteristic parameter, are obtained by test matching;

2.3) containing the expansion constitutive equation of time effect:

$\mathrm{\ϵ}=\frac{m{\[\mathrm{\σ}-c(1-e^{-dt})\]}^2}{c^2(1+{\mathrm{at}}^{-b}){(1-e^{-dt})}^2}---\left(3\right)$ A, b, c, d and m of simulating before are substituted into (3) formula must containing the expansion constitutive model of time effect;

3) according to the expansion constitutive model of equation (3) containing time effect, tunnel dilatancy is set up and supporting anti-expansion force relation equation is as follows:

$U=kD\frac{m{\[p-c(1-e^{-dt})\]}^2}{c^2(1+{\mathrm{at}}^{-b}){(1-e^{-dt})}^2}---\left(4\right)$

In formula, U is dilatancy; P is the anti-expansion force of supporting; K is the coefficient (get 0 ~ 1) relevant with tunnel geology condition; D is the tunnel excavation radius of influence; A, b, c and d are coefficient, are obtained by test;

3.1) constructing tunnel phase anti-inflated design: according to dilatancy and the anti-expansion force relation of supporting, P=0 and t=t ₀substitution formula (4) can calculate U=U ₀; Then in the design of tunnel deformation allowance, additionally consider U ₀thick dilatancy, reaches construction period anti-expansion effect; Above-mentioned t=t ₀for preliminary bracing in actual condition and two serves as a contrast interval time;

3.2) tunnel operation phase anti-inflated design: according to dilatancy and the anti-expansion force relation of supporting, t=t ₁and U=U ₁substitution formula (4) can calculate P=P ₁; Be then the opposing bulbs of pressure, in tunnel double-lining design, extra consideration is not less than P ₁hydrostatic pressure resistant power, reach operation phase anti-expansion effect; Above-mentioned t=t ₁for the tunnel service time limit, U=U ₁for the country rock dilatancy amount of construction period.