CN106126775A - Method is analyzed in the land movement that double track tunnel shield-tunneling construction causes - Google Patents

Abstract

The invention discloses a kind of land movement analysis method that double track tunnel shield-tunneling construction causes, each execution conditions, engineering equipment, geological conditions are analyzed, obtain the composition size of each factor of shield-tunneling construction based on Rankine's earth pressure theory, finite difference simulator set up by application FLAC 3D software.Respectively model being carried out single tunnel excavation in numerical model space, double track tunnel excavates simultaneously, right line is excavated after having excavated by left line, the soil body situation of movement that construction causes by simulation result analysis.Consider that the analytical expression that ground loss is caused by geological conditions is modified, the ground settlement expression formula caused in conjunction with each factor of constructing obtained based on Mindlin displacement solution, estimate ground settlement that in numerical simulation background, each construction method causes and compared with numerical simulation result, checking method for numerical simulation and the reliability of expression formula estimation.The present invention compensate for the defect that industry standard is not enough, has the directive significance of reality for Shield Tunneling technology and is widely applied prospect.

Description

Method is analyzed in the land movement that double track tunnel shield-tunneling construction causes

Technical field

The present invention relates to shield tunnel construction field, refer in particular to the land movement that a kind of double track tunnel shield-tunneling construction causes Analysis method.

Background technology

Urban rail transit in China is in the stage of a high speed development, and shield tunnel construction location is in building, ground Underground pipelines, the phenomenon such as road and bridge compact district is more and more universal.Shield tunnel construction can cause surrounding soil move horizontally and Vertical Settlement.And then, from many aspects the environment of surrounding being produced a series of impact, serious soil movement will be to building Bring severe consequence.

In tunneling shield work progress, shield machine, the impact between the soil body and building is a sufficiently complex process, The factor being directed to is numerous, thus, inevitable some defects of existence in the research of forefathers.Mainly execute in analysis tunnel Mostly have employed ideal boundary when that surrounding enviroment being affected by work simplify calculating or use empirical equation to be fitted, but institute Obtain is often excessive with reality gap.Along with the development of computer, numerical simulation is to execute by simulating reality to greatest extent Work factor, meanwhile, numerical simulation also has not reproducible use, and cost cost is big waits deficiency.Actual engineering background is past Toward being complicated, multifactor impact, how these factors in view of in numerical simulation, be that analog result is more fitted reality Border, this problem still needs carefully to consider.

At present, in the engineering practice and academic research of China, close to buildings risk is commented by underground soil excavation Estimate aspect, go back the evaluation criterion of neither one system.China defines the ground settlement upper limit that underground excavation causes in each district Value, the ground such as such as Beijing is 30mm.But the higher limit of regulation has empirical and general.Risk for different buildings Assessment and reinforcement measure are not necessarily suitable for.Therefore, the constructing tunnel impact on surrounding and the control of sedimentation are carried out in a deep going way Benchmark study processed is very important.

Summary of the invention

It is an object of the invention to overcome the deficiencies in the prior art, it is provided that the soil body that a kind of double track tunnel shield-tunneling construction causes Displacement Analysis method, the result that the method obtains has the higher goodness of fit compared with Practical Project, compensate for industry standard not The defect of foot, has innovative significance, has the directive significance of reality for Shield Tunneling technology and is widely applied prospect.

For achieving the above object, technical scheme provided by the present invention is: the soil body position that double track tunnel shield-tunneling construction causes Move analysis method, comprise the following steps:

1) double track tunnel construction earth's surface evaluated settlement

During subway shield tunnel construction, the active force to surrounding soil mainly has propelling resistance and torque resistance, wherein advances Resistance mainly has the friction between face thrust, grouting pressure and shield body and surrounding soil, and torque resistance is mainly by cutterhead The side friction of front friction and cutterhead causes, and meanwhile, shield machine deadweight causes the displacement of the periphery soil body to be contemplated that In the construction in tunnel, by the Mindlin basic solution of the displacement deformation of elastic half-space, double track tunnel construction is caused Ground settlement is estimated；

The active force being distributed on face is integrated, obtains the soil movement that single-track tunnel face thrust causes:

$w_{1q}(x,y,z,q)={\∫}_0^{2\mathrm{\π}}{\∫}_0^R{w}_{h1}(x,y,z,r,\mathrm{\θ},q)rdrd\mathrm{\θ}---\left(1\right)$

$R_1=\sqrt{x^2+{(y-rcos\mathrm{\θ})}^2+{(z-H+rsin\mathrm{\θ})}^2}---\left(2\right)$

$R_2=\sqrt{x^2+{(y-rcos\mathrm{\θ})}^2+{(z+H-rsin\mathrm{\θ})}^2}---\left(3\right)$

w_h1Vertical displacement

Now, what face thrust caused earth's surface is settled into w_1q(x, y, 0), at most numerical simulation and analytic expression In estimation, the usual value of face additional thrust, at ± 20kpa, is constructed for earth pressure balanced shield, EPBS, is considered various construction Empirical equation is given in the case of factor:

$q=\frac{10.13(1-v)E_u\mathrm{\π}v{(1-\mathrm{\ξ})}^2}{(1+v)(3-4v)Dkw}+{\mathrm{\Δp}}^{\′}---\left(4\right)$

Wherein:

The thrust that the Δ p ' otch incision soil body produces, span 10-25kpa；

E_uThe soil body not draining elastic modelling quantity, value is (36～80) E_s0.1-0.2；

E_s0.1-0.2Modulus of compressibility；

V shield machine driving speed；

W cutterhead rotating speed；

K cutterhead is remained silent part width number；

D cutter diameter；

ξ cutterhead aperture opening ratio；

It is integrated on shield length direction, obtains the friction of single line shield body as follows to the displacement expression formula of surrounding soil:

$w_{2f}(x,y,z,f)={\∫}_0^L{\∫}_0^{2\mathrm{\π}}{w}_{h1}(x-W-l,y,z,r,\mathrm{\θ},f)Rd\mathrm{\θ}dl---\left(5\right)$

$R_1=\sqrt{{(y-Rsin\mathrm{\θ})}^2+{(x-W-l)}^2+{(z-H+Rsin\mathrm{\θ})}^2}---\left(6\right)$

$R_2=\sqrt{{(y-Rsin\mathrm{\θ})}^2+{(x-W-l)}^2+{(z+H-Rsin\mathrm{\θ})}^2}---\left(7\right)$

Wherein:

w_h1(x-W-l, y, z, r, θ, f) vertical displacement

F shield body and the frictional force of surrounding soil；

The arbitrarily vertical and horizontal component on tool position is represented by following formula:

${\mathrm{pv}}_1=\frac{P_1\·rcos\mathrm{\α}}{R}---\left(8\right)$

${\mathrm{ph}}_1=\frac{P_1\·rcos\mathrm{\α}}{R}---\left(9\right)$

${\mathrm{pv}}_2=\frac{P_2\·rsin\mathrm{\α}}{R}---\left(10\right)$

${\mathrm{ph}}_2=\frac{P_2\·rcos\mathrm{\α}}{R}---\left(11\right)$

α=φ+2k π/n (12)

$p_1=\frac{3(T_1+T_3)}{{\mathrm{nR}}^2}---\left(13\right)$

$p_2=\frac{T_2}{2{\mathrm{\πR}}^{2}w}---\left(14\right)$

Wherein:

p₁The maximal friction that above each width cutter, distalmost end is subject to；

p₂Cutterhead side is considered by uniform frictional force；

Pv Vertical Concentrated Force；

The horizontal concentration power of ph；

φ is cutterhead entrance angle；

N is cutter width number；

K is kth width cutter；

T₁Cutterhead front friction torque；

T₂Dish periphery friction torque；

T₃Moment of torsion required for knife cutting dregs；

Integration obtains the soil body evaluated settlement expression formula that gravity causes and is in the vertical:

$w_{5G}(x,y,z,P)={\∫}_0^L{\∫}_{\mathrm{\π}}^{2\mathrm{\π}}{w}_{v2}(x-W-l,y,z,R,\mathrm{\θ},P\sin \mathrm{\θ})Rd\mathrm{\θ}dl---\left(15\right)$

Wherein:

w_v2(x-W-l, y, z, R, θ, Psin θ) any one gravity even distributed force component P₁The displacement component caused

Weight component at P tunnel axis；

Superposition Mindlin displacement calculation result out, therefore, is got over more than real data at face rear value of calculation Close to the soil layer in tunnel, the impact that the space between section of jurisdiction and shield settles for the soil body is the biggest, calculates based on formula Between result and reality, error is the biggest, therefore, it is possible to cause during knowing constructing tunnel is settled into numerous construction factor and soil The sedimentation that bulk diffusion causes and；

2) foundation of numerical model

It is solid element that model uses FLAC 3D finite difference software to carry out model, the soil body and slip casting, uses mole coulomb Elastic-plastic model, shield shell and lining cutting use shell unit to be simulated, for isotropic elasticity material；

Set up double-circuit tunnel model, model is applied gravity, make model be issued to balance conduct oneself with dignity, obtain model former Beginning self-weight stress field, resets the stress field of model；Then excavating tunnel, concrete excavation step is as follows:

2.1) excavate out the soil body within Grouting Circle, to excavation face apply preset even distributed force, simulation shield area Face thrust, is simplified to four width cutting dies and intends knife cutting moment of torsion, and apply side friction on the soft layer of backbreaking of cutterhead side, Apply even distributed force on shield shell and simulate jacking force for overcoming between shield shell and the soil body part of friction, apply shield in shield shell lower end Structure self gravitation, runs the time step preset, the determination mode of time step, carries out runin and dig, determine shield tunneling process before excavation At middle tunnel axis, the displacement of the top soil body is the time step less than surrounding soil activity space, tunnel, and around tunnel movable space Value U_iEstimated by following formula:

$\frac{U_i}{R}=1-{\left\{\frac{1}{1+\frac{2(1+v_u)c_u}{E_u}{\[\exp \left(\frac{N-1}{2}\right)\]}^2}\right\}}^{1/2}$

Wherein:

It is used for weighing and removes the shear strength of the soil body after mean boundary stress；

E_u,C_u,V_uIt is respectively the elastic modelling quantity of soil, modulus of shearing, Poisson's ratio under und rained condition；

The unit weight of γ soil；2.2) shield shield shell is installed outside Grouting Circle, is disturbed soil outside shield shell, the physics ginseng of soil layer Number is the reduction soil layer with layer；

2.3) at distance face preset value, remove shield shell and soft layer of backbreaking, and apply to be set to soil layer To grouting pressure, run and preset time step；

2.4) removing grouting pressure, the soil layer now weakened has obtained the reinforcing of serosity, now gives the slip casting soil body and reduction Layer assignment generates grouting layer, runs and presets time step；

2.5) shield shell departs from the grouting layer solidified, and now to installation section of jurisdiction, tunnel, cyclization is laid in section of jurisdiction can be with lining Build and bear resistance to shear of soil together, with shell unit simulation lining cutting, and run and preset time step；

3) stratum deformation law-analysing

Respectively tunnel being carried out single line and two-wire excavates simultaneously, in simulation tunnel tunneling process, soil body sedimentation gradually forms Process, wherein the maximum protuberance in tunnel occurs at tunnel bottom, and maximum settlement occurs at tunnel top axis, front end, tunnel without Retaining portion simulation tunnel cutterhead is backbreak part motion the most around under soil pressure, the housing parts simulation shield soil to motion The support action of body, the xoncrete structure that the solidification of slip casting rear slurry is formed undertakes the support action of a part, the shell of shield end Body is the lining cutting simulation in tunnel, the soil pressure that lining cutting is born around tunnel as the structure division in tunnel after having mated formation；

Tunnel is used asynchronous excavation, and tunnel subsidence is not that both sides are identical symmetrical, and the left threaded list road first excavated exists Shield machine construction completes, and in tunnel, gross weight alleviates, and can slightly swell under soil pressure, now excavates right line, and right line is being executed Below work operating mode, the left line of settling ratio wants many, and therefore, left line is compared with right line, and the tunnel subsidence in construction sinks than the tunnel deposited Fall wants big；

4) evaluated settlement contrasts with numerical simulation

Surface subsidence is estimated by sedimentation expression formula and compares with the ground settlement curve of numerical simulation；Use each The sedimentation expression formula that construction factor causes is integrated and obtains Longitudinal Settlement and the Transverse Subsidence curve on single-track tunnel earth's surface, and Contrast with numerical simulation result, find that both sides' curvilinear trend coincide；Superposition list constructing tunnel evaluated settlement expression formula obtains curve The subsidence curve caused as synchronous construction is wider with finite difference contrast subsider, settles bigger；Asynchronous construction is sunk Fall curve, the subsidence curve of first construction tunnel ground loss curve with rear construction tunnel is folded by formula estimation algorithm according to conservative approach Adding, finite difference modelling result shows, in computing, rear construction tunnel settles increase under the influence of depositing tunnel, after superposition Curve maximum settlement at move toward the left side.

The present invention compared with prior art, has the advantage that and beneficial effect:

1, analytic method used in the present invention considers the additional thrust in work progress, cutter head torque, shield gravity, cutter Dish rubs, and grouting pressure, more system are specifically comprehensively reflected the construction factor impact for tunnel subsidence；The method uses The computational methods difference that settle with past ground loss of the expression formula revising ground loss, can effectively reflect the geology of the soil body The condition impact on tunnel subsidence.

2, analytic method used in the present invention sorts out a set of evaluated settlement method relevant with constructing tunnel sequencing, The sedimentation that the asynchronous construction of tunnel synchronous construction and tunnel causes can be calculated respectively.

3, method for numerical simulation used in the present invention considers practice of construction geological conditions, Suporting structure parameter, constructs Operation in journey, support conditions and various construction parameter, such as additional thrust, cutter head torque, shield gravity, cutterhead friction, note Slurry pressure.Reappeared the process of constructing tunnel the most truly, through the inspection result that obtains of the method with Practical Project is compared has the higher goodness of fit.

Accompanying drawing explanation

Fig. 1 is face thrust integration sketch.

Fig. 2 is shield lateral forces sketch.

Fig. 3 a is shield cutter front stress sketch.

Fig. 3 b is shield cutter lateral forces sketch.

Fig. 4 is shield weight distribution sketch.

Fig. 5 is that the soil layer of model divides and physical size figure.

Y=6m section Different Strata vertical displacement figure when Fig. 6 a is left line tunnel piercing 22.5m.

Y=6m section stratum horizontal displacement figure when Fig. 6 b is left line tunnel piercing 22.5m.

Y=6m section Different Strata horizontal displacement figure when Fig. 6 c is left line tunnel piercing 22.5m.

Tunnel axis section stratum vertical displacement figure when Fig. 6 d is left line driving 22.5m.

Fig. 6 e is double track tunnel tunnel Y=6m section Different Strata vertical displacement figure when simultaneously tunneling 22.5m.

Fig. 6 f is double track tunnel horizontal displacement figure of tunnel y=6m section diverse location when simultaneously tunneling 22.5m.

Fig. 6 g is double track tunnel horizontal displacement figure of tunnel y=6m section Different Strata when simultaneously tunneling 22.5m.

Fig. 6 h is that left line completes y=6m section Different Strata sedigraph in tunnel during rear right line tunnel piercing 22.5m.

Fig. 6 i is left line left threaded list road y=6m section diverse location horizontal displacement figure when becoming rear right line tunnel piercing 22.5m.

Fig. 6 j is the horizontal displacement figure that left line completes rear right line tunnel piercing 22.5m tunnel y=6m section Different Strata.

Fig. 7 a is that left line tunnel piercing 16.5m construction Longitudinal Settlement numerical simulation estimates comparison diagram with formula.

Fig. 7 b is that left line construction face (y=0m) section Transverse Subsidence numerical simulation estimates comparison diagram with formula.

When Fig. 7 c is left line construction driving 22.5m, y=6m section Transverse Subsidence numerical simulation estimates comparison diagram with formula.

Fig. 7 d is for revising soil body damage sedimentation formula and Wei Gang soil body damage formula comparison diagram.

Fig. 7 e is that two-wire synchronizes y=6m section Transverse Subsidence numerical simulation and formula estimation comparison diagram during driving 22.5m.

When Fig. 7 f is for depositing right line left line construction driving 22.5m, y=6m section Transverse Subsidence numerical simulation is estimated with formula Comparison diagram.

Detailed description of the invention

Below in conjunction with specific embodiment, the invention will be further described.

Method is analyzed in the land movement that double track tunnel shield-tunneling construction described in the present embodiment causes, and comprises the following steps:

1. double track tunnel construction earth's surface evaluated settlement

During subway shield tunnel construction, the active force to surrounding soil mainly has propelling resistance and torque resistance, wherein advances Resistance mainly has the friction between face thrust, grouting pressure and shield body and surrounding soil, and torque resistance is mainly by cutterhead The side friction of front friction and cutterhead causes.Meanwhile, shield machine deadweight causes the displacement of the periphery soil body to be contemplated that In the construction in tunnel.By the Mindlin basic solution of the displacement deformation of elastic half-space, double track tunnel construction is caused Ground settlement is estimated.Face thrust integration sketch is as shown in Figure 1.

The active force being distributed on face is integrated, the soil layer position that single-track tunnel face thrust causes can be obtained Move:

$w_{1q}(x,y,z,q)={\∫}_0^{2\mathrm{\π}}{\∫}_0^R{w}_{h1}(x,y,z,r,\mathrm{\θ},q)rdrd\mathrm{\θ}---\left(16\right)$

$R_1=\sqrt{x^2+{(y-rcos\mathrm{\θ})}^2+{(z-H+r\sin \mathrm{\θ})}^2}---\left(17\right)$

$R_2=\sqrt{x^2+{(y-rcos\mathrm{\θ})}^2+{(z+H-rsin\mathrm{\θ})}^2}---\left(18\right)$

w_h1Vertical displacement

Now, what face thrust caused earth's surface is settled into w_1q(x,y,0).At most numerical simulation and analytic expression In estimation, the general value of face additional thrust is at ± 20kpa.Earth pressure balanced shield, EPBS is constructed, considers various construction Empirical equation is given in the case of factor:

$q=\frac{10.13(1-v)E_u\mathrm{\π}v{(1-\mathrm{\ξ})}^2}{(1+v)(3-4v)Dkw}+{\mathrm{\Δp}}^{\′}---\left(19\right)$

Wherein:

The thrust that the Δ p ' otch incision soil body produces, span 10-25kpa；

E_uThe soil body not draining elastic modelling quantity, value is (36～80) E_s0.1-0.2；

E_s0.1-0.2Modulus of compressibility (MPa)；

V shield machine driving speed (cm/min)；

W cutterhead rotating speed (r/min)；

K cutterhead is remained silent part width number；

D cutter diameter；

ξ cutterhead aperture opening ratio (%)；

Shield lateral forces sketch is as shown in Figure 2.

It is integrated on shield length direction, single line shield body can be obtained and rub the displacement expression formula to surrounding soil such as Under:

$w_{2f}(x,y,z,f)={\∫}_0^L{\∫}_0^{2\mathrm{\π}}{w}_{h1}(x-W-l,y,z,r,\mathrm{\θ},f)Rd\mathrm{\θ}dl---\left(20\right)$

$R_1=\sqrt{{(y-Rsin\mathrm{\θ})}^2+{(x-W-l)}^2+{(z-H+Rsin\mathrm{\θ})}^2}---\left(21\right)$

$R_2=\sqrt{{(y-Rsin\mathrm{\θ})}^2+{(x-W-l)}^2+{(z+H-Rsin\mathrm{\θ})}^2}---\left(22\right)$

Wherein:

w_h1(x-W-l, y, z, r, θ, f) vertical displacement

F shield body and the frictional force of surrounding soil；

Shield cutter front is with lateral forces sketch as best shown in figures 3 a and 3b.

The arbitrarily vertical and horizontal component on tool position can be represented by following formula:

${\mathrm{pv}}_1=\frac{P_1\·rcos\mathrm{\α}}{R}---\left(23\right)$

${\mathrm{ph}}_1=\frac{P_1\·rcos\mathrm{\α}}{R}---\left(24\right)$

${\mathrm{pv}}_2=\frac{P_2\·rsin\mathrm{\α}}{R}---\left(25\right)$

${\mathrm{ph}}_2=\frac{P_2\·rcos\mathrm{\α}}{R}---\left(26\right)$

α=φ+2k π/n (27)

$p_1=\frac{3(T_1+T_3)}{{\mathrm{nR}}^2}---\left(28\right)$

$p_2=\frac{T_2}{2{\mathrm{\πR}}^{2}w}---\left(29\right)$

Wherein:

p₁The maximal friction that above each width cutter, distalmost end is subject to；

p₂Cutterhead side is considered by uniform frictional force；

Pv Vertical Concentrated Force；

The horizontal concentration power of ph；

φ is cutterhead entrance angle；

N is cutter width number；

K is kth width cutter；

T₁Cutterhead front friction torque；

T₂Dish periphery friction torque；

T₃Moment of torsion required for knife cutting dregs；

Shield weight distribution sketch is as shown in Figure 4.

Integration can obtain the soil body evaluated settlement expression formula that gravity causes and is in the vertical:

$w_{5G}(x,y,z,P)={\∫}_0^L{\∫}_{\mathrm{\π}}^{2\mathrm{\π}}{w}_{v2}(x-W-l,y,z,R,\mathrm{\θ},P\sin \mathrm{\θ})Rd\mathrm{\θ}dl---\left(30\right)$

Wherein:

w_v2(x-W-l, y, z, R, θ, Psin θ) any one gravity even distributed force component P₁The displacement component caused

Weight component at P tunnel axis；

Superposition Mindlin displacement calculation result out, therefore, is got over more than real data at face rear value of calculation Close to the soil layer in tunnel, the impact that the space between section of jurisdiction and shield settles for the soil body is the biggest, calculates based on formula Between result and reality, error is the biggest.In sum, it is known that cause during constructing tunnel be settled into numerous construction because of The sedimentation that causes with ground loss of element and.

2. the foundation of numerical model

Stratum and mechanical parameters that shield interval uses are as shown in the table:

It is solid element that model uses FLAC 3D finite difference software to carry out model, the soil body and slip casting, uses mole coulomb Elastic-plastic model, shield shell and lining cutting use shell unit to be simulated, for isotropic elasticity material.

Set up double-circuit tunnel model, model is applied gravity, make model be issued to balance conduct oneself with dignity, obtain model former Beginning self-weight stress field, resets the stress field of model.Then excavating tunnel, the every ring width in tunnel is 1.5m, specifically opens Dig step as follows:

2.1: excavate out the soil body 1.5m within Grouting Circle, excavation face is applied the even distributed force of-0.3Mpa, simulation shield Face thrust, be simplified to four width cutting dies intend knife cutting moments of torsion, and on the soft layer of backbreaking of cutterhead side apply side Friction, applies even distributed force on shield shell and simulates jacking force for overcoming between shield shell and the soil body part of friction, under shield shell End applies shield self gravitation, runs certain time step.The determination mode of time step, carries out runin and digs, determine shield before excavation In tunneling process, at tunnel axis, the displacement of the top soil body is the time step less than surrounding soil activity space, tunnel, around tunnel Movable gap value U_iEstimated by following formula:

$\frac{U_i}{R}=1-{\left\{\frac{1}{1+\frac{2(1+v_u)c_u}{E_u}{\[\exp \left(\frac{N-1}{2}\right)\]}^2}\right\}}^{1/2}$

Wherein:

It is used for weighing and removes the shear strength of the soil body after mean boundary stress；

E_u,C_u,V_uIt is respectively the elastic modelling quantity of soil, modulus of shearing, Poisson's ratio under und rained condition；

The unit weight of γ soil；2.2: shield shield shell is installed outside Grouting Circle, is the disturbed soil of thickness 7cm outside shield shell, soil The reduction soil layer that physical parameter is same layer of layer, advances 3 rings for this；

2.3: at distance face 6～7.5m, remove shield shell and soft layer of backbreaking, and soil layer is applied 0.2Mpa Grouting pressure, run certain time step；

2.4: remove grouting pressure, the soil layer now weakened has obtained the reinforcing of serosity, now gives the slip casting soil body and reduction Layer assignment generates grouting layer, runs certain time step；

2.5: shield shell departs from the grouting layer solidified, now to installation section of jurisdiction, tunnel, cyclization is laid in section of jurisdiction can be with lining Build and bear resistance to shear of soil together, with shell unit simulation lining cutting, and run certain time step.

3. stratum deformation law-analysing

Respectively tunnel being carried out single line and two-wire excavates simultaneously, in simulation tunnel tunneling process, soil body sedimentation gradually forms Process.Wherein the maximum protuberance in tunnel occurs at tunnel bottom, and maximum settlement occurs at tunnel top axis.Front end, tunnel without Retaining portion simulation tunnel cutterhead is backbreak part motion the most around under soil pressure, the housing parts simulation shield soil to motion The support action of body, the xoncrete structure that the solidification of slip casting rear slurry is formed undertakes the support action of a part.The shell of shield end Body is the lining cutting simulation in tunnel, the soil pressure that lining cutting is born around tunnel as the structure division in tunnel after having mated formation.

Tunnel is used asynchronous excavation, and tunnel subsidence is not that both sides are identical symmetrical, and the left threaded list road first excavated exists Shield machine construction completes, and in tunnel, gross weight alleviates, and can slightly swell under soil pressure.Now excavating right line, right line is being executed Below work operating mode, the left line of settling ratio wants many, and therefore, left line is compared with right line, and the tunnel subsidence in construction sinks than the tunnel deposited Fall wants big.

4. evaluated settlement contrasts with numerical simulation

Surface subsidence is estimated by sedimentation expression formula and compares with the ground settlement curve of numerical simulation.Use each The sedimentation expression formula that construction factor causes is integrated and obtains Longitudinal Settlement and the Transverse Subsidence curve on single-track tunnel earth's surface, and After contrasting with numerical simulation result, finding that both sides' curvilinear trend coincide, size is basically identical.The sedimentation of superposition list constructing tunnel is estimated It is wider with finite difference contrast subsider that operator expression formula obtains the subsidence curve that curve causes as synchronous construction, settles bigger. For the subsidence curve of asynchronous construction, formula estimation algorithm according to conservative approach by elder generation's construction tunnel ground loss curve and rear construction The subsidence curve superposition in tunnel, finite difference modelling result shows, in computing, rear construction tunnel is under the influence of depositing tunnel Sedimentation increases, and moves toward the left side at the curve maximum settlement after superposition.

We are with station, No. three line Milky Way five mountains of Guangzhou Underground as engineering background below, to each execution conditions, engineering equipment, Geological conditions is analyzed, and obtains the composition size of each factor of shield-tunneling construction based on Rankine's earth pressure theory, applies FLAC 3D Finite difference simulator set up by software.Respectively model is carried out single tunnel excavation in numerical model space, double track tunnel is opened simultaneously Dig, right line is excavated after having excavated by left line, the soil body situation of movement that construction causes by simulation result analysis.Consider ground The analytical expression that ground loss is caused by matter condition is modified, in conjunction with the construction obtained based on Mindlin displacement solution each because of The ground settlement expression formula that element causes, has estimated ground settlement and Numerical-Mode that in numerical simulation background, each construction method causes Intend result to compare, checking method for numerical simulation and the reliability of expression formula estimation.Specific as follows:

1. use classical mathematics, mechanics answer and Mindlin displacement solution to face thrust, cutter head torque, grouting pressure, The sedimentation that shield body friction, these construction factors of shield gravity cause calculates, and obtains reflecting connection between soil property and subsider The half theoretical semiempirical formula that the suitability of system is stronger comprehensively analyzes the ground settlement that single line shield-tunneling construction disturbance causes.Use Principle of stacking takes the left line of construction disturbance impact and right line into consideration, obtains the earth's surface construction settlement expression that two-wire tunnels simultaneously Formula.Ground settlement after stable for the ground loss ground settlement after Smax has been constructed as left line, and consider with right line The ground settlement that construction disturbance causes is overlapped, and obtains the ground settlement field of the asynchronous driving in left and right.

2. from Rankine's earth pressure theory, determine shield tunnelling parameters according to engineering geological condition, construction parameter come Finally determining the type selecting of shield machine, the soil layer of model divides with physical size as shown in Figure 5.Based on a determination that construction parameter set up Numerical model, carries out numerical value excavation according to concrete construction procedure in the model space, and become more meticulous construction simulation process.

3. it is analyzed based on Angiostrangylus cantonensis five mountain double track tunnel engineering, it is considered to practice of construction geological conditions, equipment etc. Determine the load of numerical simulation, the size of structural model, the parameters for numerical simulation such as step number of excavation.By to the FLAC set up 3D model is analyzed, and obtains the vertically movable of each soil layer and transverse shifting rule, as shown in Fig. 6 a～6j.

4. research two-wire synchronizes excavation, and the asynchronous excavation of two-wire causes the land movement of periphery, uses Matlab to estimation public affairs Formula is integrated calculating, and finite difference modelling result is contrasted with ground settlement estimation result, sums up its characteristic rule, As shown in Fig. 7 a～7f.It will be seen that single line is constructed, two-wire is constructed, the formula of the asynchronous construction of two-wire is estimated result and has simultaneously The analog result of limit difference is consistent, also demonstrates the reliability of formula estimation algorithm and Method for Numerical.

Embodiment described above is only the preferred embodiments of the invention, not limits the practical range of the present invention with this, therefore The change that all shapes according to the present invention, principle are made, all should contain within the scope of the present invention.

Claims (1)

1. method is analyzed in the land movement that double track tunnel shield-tunneling construction causes, it is characterised in that comprise the following steps:

1) double track tunnel construction earth's surface evaluated settlement

During subway shield tunnel construction, the active force to surrounding soil mainly has propelling resistance and torque resistance, wherein propelling resistance Mainly having the friction between face thrust, grouting pressure and shield body and surrounding soil, torque resistance is mainly by cutterhead front The side friction of friction and cutterhead causes, and meanwhile, shield machine deadweight causes the displacement of the periphery soil body it is contemplated that tunnel In the construction in road, by the Mindlin basic solution of the displacement deformation of elastic half-space, the earth's surface caused that double track tunnel is constructed Sedimentation is estimated；

The active force being distributed on face is integrated, obtains the soil movement that single-track tunnel face thrust causes:

$w_{1q}(x,y,z,q)={\∫}_0^{2\mathrm{\π}}{\∫}_0^R{w}_{h1}(x,y,z,r,\mathrm{\θ},q)rdrd\mathrm{\θ}---\left(1\right)$

$R_1=\sqrt{x^2+{(y-rcos\mathrm{\θ})}^2+{(z-H+rsin\mathrm{\θ})}^2}---\left(2\right)$

$R_2=\sqrt{x^2+{(y-rcos\mathrm{\θ})}^2+{(z+H-rsin\mathrm{\θ})}^2}---\left(3\right)$

w_h1Vertical displacement

Now, what face thrust caused earth's surface is settled into w_1q(x, y, 0), estimates in most numerical simulation and analytic expression In, the usual value of face additional thrust, at ± 20kpa, is constructed for earth pressure balanced shield, EPBS, is considered various construction factor In the case of provide empirical equation:

$q=\frac{10.13(1-v)E_u\mathrm{\π}v{(1-\mathrm{\ξ})}^2}{(1+v)(3-4v)Dkw}+{\mathrm{\Δp}}^{\′}---\left(4\right)$

Wherein:

The thrust that the Δ p ' otch incision soil body produces, span 10-25kpa；

E_uThe soil body not draining elastic modelling quantity, value is

E_s0.1-0.2Modulus of compressibility；

V shield machine driving speed；

W cutterhead rotating speed；

K cutterhead is remained silent part width number；

D cutter diameter；

ξ cutterhead aperture opening ratio；

It is integrated on shield length direction, obtains the friction of single line shield body as follows to the displacement expression formula of surrounding soil:

$w_{2f}(x,y,z,f)={\∫}_0^L{\∫}_0^{2\mathrm{\π}}{w}_{h1}(x-W-l,y,z,r,\mathrm{\θ},f)Rd\mathrm{\θ}dl---\left(5\right)$

$R_1=\sqrt{{(y-Rsin\mathrm{\θ})}^2+{(x-W-l)}^2+{(z-H+Rsin\mathrm{\θ})}^2}---\left(6\right)$

$R_2=\sqrt{{(y-Rsin\mathrm{\θ})}^2+{(x-W-l)}^2+{(z+H-Rsin\mathrm{\θ})}^2}---\left(7\right)$

Wherein:

w_h1(x-W-l, y, z, r, θ, f) vertical displacement

F shield body and the frictional force of surrounding soil；

The arbitrarily vertical and horizontal component on tool position is represented by following formula:

${\mathrm{pv}}_1=\frac{P_1\·rcos\mathrm{\α}}{R}---\left(8\right)$

${\mathrm{ph}}_1=\frac{P_1\·rcos\mathrm{\α}}{R}---\left(9\right)$

${\mathrm{pv}}_2=\frac{P_2\·rsin\mathrm{\α}}{R}---\left(10\right)$

${\mathrm{ph}}_2=\frac{P_2\·rcos\mathrm{\α}}{R}---\left(11\right)$

α=φ+2k π/n (12)

$p_1=\frac{3(T_1+T_3)}{{\mathrm{nR}}^2}---\left(13\right)$

$p_2=\frac{T_2}{2{\mathrm{\πR}}^{2}w}---\left(14\right)$

Wherein:

p₁The maximal friction that above each width cutter, distalmost end is subject to；

p₂Cutterhead side is considered by uniform frictional force；

Pv Vertical Concentrated Force；

The horizontal concentration power of ph；

φ is cutterhead entrance angle；

N is cutter width number；

K is kth width cutter；

T₁Cutterhead front friction torque；

T₂Dish periphery friction torque；

T₃Moment of torsion required for knife cutting dregs；

Integration obtains the soil body evaluated settlement expression formula that gravity causes and is in the vertical:

$w_{5G}(x,y,z,P)={\∫}_0^L{\∫}_{\mathrm{\π}}^{2\mathrm{\π}}{w}_{v2}(x-W-l,y,z,R,\mathrm{\θ},Psin\mathrm{\θ})Rd\mathrm{\θ}dl---\left(15\right)$

Wherein:

w_v2(x-W-l, y, z, R, θ, P sin θ) any one gravity even distributed force component P₁The displacement component caused

Weight component at P tunnel axis；

Superposition Mindlin displacement calculation result out at face rear value of calculation more than real data, therefore, closer to The soil layer in tunnel, the impact that the space between section of jurisdiction and shield settles for the soil body is the biggest, the result calculated based on formula And error is the biggest between reality, therefore, it is possible to the numerous construction factor that is settled into caused during knowing constructing tunnel damages with the soil body Lose the sedimentation that causes and；

2) foundation of numerical model

It is solid element that model uses FLAC 3D finite difference software to carry out model, the soil body and slip casting, uses a mole coulomb bullet to mould Property model, shield shell and lining cutting use shell unit to be simulated, for isotropic elasticity material；

Set up double-circuit tunnel model, model is applied gravity, make model be issued to balance conduct oneself with dignity, obtain model original certainly Weight stress field, resets the stress field of model；Then excavating tunnel, concrete excavation step is as follows:

2.1) excavate out the soil body within Grouting Circle, to excavation face apply preset even distributed force, simulation shield face push away Power, is simplified to four width cutting dies and intends knife cutting moment of torsion, and apply side friction on the soft layer of backbreaking of cutterhead side, at shield shell Upper applying even distributed force simulates jacking force for overcoming between shield shell and the soil body part of friction, apply in shield shell lower end shield from Heavy sensation of the body power, runs the time step preset, the determination mode of time step, carries out runin and dig, determine tunnel in shield tunneling process before excavation At road axis, the displacement of the top soil body is the time step less than surrounding soil activity space, tunnel, movable gap value U around tunnel_i Estimated by following formula:

$\frac{U_i}{R}=1-{\left\{\frac{1}{1+\frac{2(1+v_u)c_u}{E_u}{\[\exp \left(\frac{N-1}{2}\right)\]}^2}\right\}}^{1/2}$

Wherein:

It is used for weighing and removes the shear strength of the soil body after mean boundary stress；

E_u,C_u,V_uIt is respectively the elastic modelling quantity of soil, modulus of shearing, Poisson's ratio under und rained condition；

The unit weight of γ soil；

2.2) installing shield shield shell outside Grouting Circle, be disturbed soil outside shield shell, the physical parameter of soil layer is the reduction soil of same layer Layer；

2.3) at distance face preset value, remove shield shell and soft layer of backbreaking, and soil layer applying setting is noted Slurry pressure, runs and presets time step；

2.4) removing grouting pressure, the soil layer now weakened has obtained the reinforcing of serosity, now gives the slip casting soil body and weakens layer tax Value generates grouting layer, runs and presets time step；

2.5) shield shell departs from the grouting layer solidified, and now to installation section of jurisdiction, tunnel, cyclization is laid in section of jurisdiction can be with lining cutting one Rise and bear resistance to shear of soil, with shell unit simulation lining cutting, and run and preset time step；

3) stratum deformation law-analysing

Respectively tunnel being carried out single line and two-wire excavates simultaneously, in simulation tunnel tunneling process, the soil body settles the mistake gradually formed Journey, wherein the maximum protuberance in tunnel occurs at tunnel bottom, and maximum settlement occurs at tunnel top axis, and front end, tunnel is without propping up Protect partial simulation tunnel cutterhead to backbreak part motion the most around under soil pressure, the housing parts simulation shield soil body to motion Support action, slip casting rear slurry solidification formed xoncrete structure undertake a part support action, the housing of shield end Lining cutting for tunnel is simulated, the soil pressure that lining cutting is born around tunnel as the structure division in tunnel after having mated formation；

Tunnel is used asynchronous excavation, and tunnel subsidence is not that both sides are identical symmetrical, and the left threaded list road first excavated is in shield Machine has been constructed, and in tunnel, gross weight alleviates, and can slightly swell under soil pressure, now excavates right line, and right line is in construction work Below condition, the left line of settling ratio wants many, and therefore, left line is compared with right line, and the tunnel subsidence in construction is wanted than the tunnel subsidence deposited Greatly；

4) evaluated settlement contrasts with numerical simulation

Surface subsidence is estimated by sedimentation expression formula and compares with the ground settlement curve of numerical simulation；Use each construction The sedimentation expression formula that factor causes is integrated and obtains the Longitudinal Settlement on single-track tunnel earth's surface and Transverse Subsidence curve, and with number Value analog result contrast, finds that both sides' curvilinear trend coincide；Superposition list constructing tunnel evaluated settlement expression formula obtains curve conduct The subsidence curve that synchronous construction causes is wider with finite difference contrast subsider, settles bigger；Sedimentation for asynchronous construction is bent Line, first construction tunnel ground loss curve is superposed with the subsidence curve of rear construction tunnel by formula estimation algorithm according to conservative approach, Finite difference modelling result shows, in computing, rear construction tunnel settles increase, the song after superposition under the influence of depositing tunnel Move toward the left side at line maximum settlement.