CPC G06F 30/23 (2020.01) [G06F 30/13 (2020.01); G05B 2219/23006 (2013.01); G06F 2111/10 (2020.01); G06F 2119/14 (2020.01)] | 3 Claims |
1. A design method for parameters of cross sections of a single-hole four- lane highway tunnel, wherein comprising the following steps:
(1) determining surrounding rock pressure:
calculating, based on grade parameters of surrounding rock, surrounding rock pressure of the single-hole four-lane highway tunnel, wherein the surrounding rock pressure of the single-hole four-lane highway tunnel comprises vertical uniform pressure q and horizontal uniform pressure e;
(2) constructing numerical models under different flatness ratios:
selecting, based on a construction limit of the tunnel, a series of cross section flatness ratio parameters, and respectively constructing tunnel numerical calculation models by using MIDAS/GTS finite element software, wherein when the tunnel has a cross section with an inverted arch, flatness ratios select multiple groups of different numerical values from 0.500 to 0.750, and when the tunnel has a cross section without an inverted arch, flatness ratios select multiple groups of different numerical values from 0.400-0.560;
(3) calculating internal force of lining structures:
calculating stress on the lining structures of the cross sections of the tunnel under different flatness ratios by using the MIDAS/GTS finite element software, to obtain axial force N and bending moments M of the lining structures;
(4) calculating safety coefficients of the lining structures:
calculating, based on calculation results of the axial force N and the bending moments M of linings at different positions of the cross sections, and physical and mechanical parameters of lining materials, the safety coefficients K of the lining structures at different positions of the cross sections;
(5) performing contrastive analysis on the cross sections under different flatness ratios:
respectively performing contrastive analysis of safety and economic efficiency on cross section forms under different flatness ratios; and
(6) obtaining reasonable cross section forms:
summarizing analysis results of safety and economic efficiency of the lining structures of the tunnel, taking a flatness ratio overlapping range of an optimal safety interval and an optimal economic efficiency interval as a flatness ratio optimal interval, and selecting flatness ratio parameters in the flatness ratio optimal interval to perform design of the cross sections of the single-hole four-lane highway tunnel;
wherein the embodiment of step [4] is as follows:
for a pre-designed lining reinforced concrete component, a depth x of compression zone of each cross section may be calculated first according to the formula below, in a direction perpendicular to the cross sections, and based on a tension and compression balance:
Rg(Ag−A′g)=Rwbx;
when the depth x of compression zone of the cross sections of the tunnel is less than or equal to 0.55h02, a secondary lining is a component with large eccentricity, and the safety coefficient of each cross section is calculated according to the formula below:
![]() at the moment, a position of a neutral axis is determined according to the formula below:
Rg(Age∓A′ge′)=Rwbx(e−h0+x/2);
when the axial force N acts between a gravity center of a rebar Ag and a gravity center of a rebar A′g, a second term on a left side of the above formula takes a positive sign; and when the axial force N acts outside rather than between the gravity center of the rebar Ag and the gravity center of the rebar A′g, the second term takes a negative sign;
when a stressed rebar is considered during calculation, a depth of compression zone of concrete should meet the requirement that x is greater than or equal to 2a′, and if the requirement is not met, calculation is performed according to the formula below:
![]() when the depth x of compression zone of the cross sections of the tunnel is greater than 0.55h0, a secondary lining is a component with small eccentricity, and the safety coefficient of each cross section is calculated according to the formula below:
![]() and
when the axial force N acts between the gravity center of the rebar Ag and the gravity center of the rebar A′g, the following requirements should be met:
![]() in the formula: N represents axial force (MN); M represents a bending moment (MN·m); Rg represents a standard value of tensile strength or compressive strength of a rebar; Rw represents limit bending compressive strength of concrete, and Rw=1.25 Ra; Ag and A′g represent cross section areas (m2) of a rebar in a tensile zone and a compressive zone; a′ represents a distance (m) from the gravity center of the rebar A′g to a nearest edge of a cross section; a represents a distance (m) from the gravity center of the rebar Ag to the nearest edge of the cross section; h represents a height of a cross section; h0 represents an effective height (m) of a cross section, and h0=h−a; x represents a depth (m) of compression zone of concrete; b represents a width (m) of a rectangular cross section; e and e′ represent distances from the gravity centers of the rebars Ag and A′g to an acting point of the axial force; and K represents a safety coefficient.
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