CN101899981B - Method for reducing abnormal damage of hob in tunnel excavating process of shield machine - Google Patents

Abstract

The invention discloses a method for reducing abnormal damage of a hob in the tunnel excavating process of a shield machine. In the method, critical minimum penetration and critical maximum penetration of the shield machine in the excavating process are calculated by acquiring relevant parameters of the hob and stratigraphic rocks, so that the thrust of the shield machine in the excavating process is adjusted to control the actual penetration to be in the range of the critical minimum penetration and the critical maximum penetration. In the method, the penetration range can be adjusted according to the change of the rock strength and the cutter wear condition in the excavating process to be controlled to between the critical minimum penetration and the critical maximum penetration, so that the abnormal damage of the hob in the hard rock excavating process of the shield machine is reduced, the rock-breaking efficiency of the hob is improved, the design and the arrangement of the cutters are improved, the excavating parameters are optimized, and the like.

Description

Be applied to shield machine and in tunnel excavating process, reduce the unusual method of damaging of hobboing cutter

Technical field

The present invention relates to the tunnel piercing technology of shield machine, the special various factors that influences broken rock load of hobboing cutter and the critical pile penetration of influence that is directed against is analyzed, and proposes the method for a kind of effective minimizing hobboing cutter unusual damage in tunneling process.

Background technology

Along with the development of shield machine manufacturing technology, the range of application of shield machine constantly enlarges.Particularly along with the high speed development of metro construction all over the world, the stratum that shield tunnel is run into becomes increasingly complex, and an often same tunnel not only will pass through soil layer, also will pass through hard rock simultaneously.In order to satisfy this growing needs, compound shield machine has appearred, traditional shield machine only is applicable to soil layer, expanded to also and can be applied to ground consisting of hard rock.But a large amount of engineering practices prove that shield machine is applied to hard rock or compound stratum has run into a lot of difficulties; Cause the unusual well damage of cutter (cutter ring eccentric wear, damage of bearings etc.); The cutter consumption is big, and drivage efficiency hangs down inferior problem, has greatly restricted the application of shield machine in hard rock.

Therefore, how effectively reducing hobboing cutter, to damage, improve the hobboing cutter efficiency of breaking rock be the main difficult problem that shield machine faces in the hard rock driving.

Summary of the invention

Based on above-mentioned situation; The present invention is through investigate and analyse the damaged condition of shield structure hobboing cutter in the hard rock in a large number; Principal mode and mechanical mechanism that the further investigation hobboing cutter damages; Purpose is to provide a kind of hobboing cutter unusual method of damaging in tunneling process that reduces, to realize that shield machine effectively reduces hobboing cutter and damages, improves the hobboing cutter efficiency of breaking rock, improves Tool Design and layout, optimizes boring parameter etc. in hard rock.

The technical scheme that the present invention adopted: a kind of shield machine that is applied to reduces the unusual method of damaging of hobboing cutter in tunnel excavating process, may further comprise the steps:

(1) gathers the relevant parameter of hobboing cutter and formation rock, comprise nominal load, rock uniaxiality strength and the Tensile Strength of Rock of hobboing cutter radius, hobboing cutter point of a knife width, point width, point of a knife pressure distribution coefficient, hobboing cutter;

(2) utilize the above-mentioned relevant parameter that collects to calculate the drag overall square that the hobboing cutter rotation process receives;

(3) relevant parameter that combines above-mentioned steps (1), (2) to obtain calculates the critical minimum pile penetration and the critical maximum pile penetration of hobboing cutter;

(4) thrust of adjustment shield machine in tunneling process is controlled within the span of critical minimum pile penetration and critical maximum pile penetration its actual pile penetration.

Critical minimum pile penetration h in the above-mentioned steps (3) _MinDesign formulas following:

$h_{\min }={\left(\frac{{\mathrm{CR}}^{2}T}{99.3(1+\mathrm{\ψ})T_f}\sqrt[3]{\frac{S}{\sqrt{\mathrm{RT}}}{{\mathrm{\σ}}_c}^2{\mathrm{\σ}}_t}\right)}^{-1.196}$

In the formula:

C---dimensionless factor;

R---hobboing cutter radius;

T---hobboing cutter point of a knife width;

ψ---point of a knife pressure distribution coefficient;

S---point width;

σ _c---rock uniaxiality strength;

σ _t---Tensile Strength of Rock;

T _f---the drag overall square that the hobboing cutter rotation process receives.

Critical maximum pile penetration h in the above-mentioned steps (3) _MaxDesign formulas following:

$h_{\max }={\left\{\frac{0.2094\×\mathrm{CRT}}{(1+\mathrm{\ψ})F_m}\sqrt[3]{\frac{S}{\sqrt{\mathrm{RT}}}{{\mathrm{\σ}}_c}^2{\mathrm{\σ}}_t}\right\}}^{-2.976}$

In the formula:

C---dimensionless factor;

R---hobboing cutter radius;

T---hobboing cutter point of a knife width;

ψ---point of a knife pressure distribution coefficient;

S---point width;

σ _c---rock uniaxiality strength;

σ _t---Tensile Strength of Rock;

The nominal load of Fm---hobboing cutter.

The shield machine that is applied to according to the invention reduces the unusual method of damaging of hobboing cutter in tunnel excavating process, can realize through following concrete step:

(1) gathers the relevant parameter of boring parameter and hobboing cutter, comprise the nominal load of native cabin average pressure, dregs friction factor, compressive strength of rock and hobboing cutter;

(2) according to the graph of relation of native cabin average pressure and frictional resistance moment, the drag overall square that the hobboing cutter rotation process receives when tabling look-up the dregs friction factor that obtains collection in above-mentioned steps (1), i.e. frictional resistance moment;

(3) according to the graph of relation of critical minimum pile penetration and frictional resistance moment, the critical minimum pile penetration of hobboing cutter under the compressive strength of rock that obtains in above-mentioned steps (1), to gather of tabling look-up;

(4) according to the graph of relation of critical maximum pile penetration and compressive strength of rock, the critical maximum pile penetration of hobboing cutter under the nominal load that obtains the hobboing cutter of collection in above-mentioned steps (1) of tabling look-up;

(5) thrust of adjustment shield machine in tunneling process is controlled within the span of critical minimum pile penetration and critical maximum pile penetration its actual pile penetration.

In addition, the shield machine that is applied to according to the invention reduces the unusual method of damaging of hobboing cutter in tunnel excavating process, also can realize through following concrete step:

(1) gathers the relevant parameter of boring parameter and hobboing cutter, comprise the point of a knife width of native cabin average pressure, dregs friction factor, compressive strength of rock and hobboing cutter;

(2) according to the graph of relation of native cabin average pressure and frictional resistance moment, the drag overall square that the hobboing cutter rotation process receives when tabling look-up the dregs friction factor that obtains collection in above-mentioned steps (1), i.e. frictional resistance moment;

(3) according to the graph of relation of critical minimum pile penetration and frictional resistance moment, the critical minimum pile penetration of hobboing cutter under the compressive strength of rock that obtains in above-mentioned steps (1), to gather of tabling look-up;

(4) according to the graph of relation of critical maximum pile penetration and compressive strength of rock, the critical maximum pile penetration of hobboing cutter under the point of a knife width that obtains the hobboing cutter of collection in above-mentioned steps (1) of tabling look-up;

(5) thrust of adjustment shield machine in tunneling process is controlled within the span of critical minimum pile penetration and critical maximum pile penetration its actual pile penetration.

Wherein, In the graph of relation of the above-mentioned critical minimum pile penetration of stating step (3) and frictional resistance moment; If the curve of friction factor that does not collect or compressive strength of rock; At first search adjacent curve values, estimate the frictional resistance moment or the critical minimum pile penetration of relevant parameter value then through interpolation method.In the critical maximum pile penetration of step (4) and the graph of relation of compressive strength of rock; If the curve of the nominal load of the hobboing cutter that does not collect or point of a knife width; At first search adjacent curve values, estimate the critical maximum pile penetration of relevant parameter value then through interpolation method.

The present invention investigates and analyses through the damaged condition to shield machine roller cutter; Mechanical mechanism through hobboing cutter is damaged is studied; Using the CSM model finds the solution the broken rock load of hobboing cutter; The critical maximum pile penetration of hobboing cutter damage and the critical minimum pile penetration account form that hobboing cutter can not rotate (eccentric wear) have been obtained; And analyze with the various factors of the critical pile penetration of influence influencing the broken rock load of hobboing cutter, a kind of hobboing cutter unusual method of damaging in tunneling process that reduces is proposed, adjust the pile penetration scope according to the rock strength of tunneling process and the variation of tool wear situation; It is controlled between critical minimum pile penetration and the critical maximum pile penetration, damages, improved the hobboing cutter efficiency of breaking rock unusually, improve Tool Design and layout, optimize boring parameter etc. thereby reduced the hobboing cutter of shield machine in hard rock.

Description of drawings

Fig. 1 (a), Fig. 1 (b) are the force analysis sketch map of hobboing cutter;

Fig. 2 is the graph of relation of contact angle according to the invention

and pile penetration h;

Fig. 3 is the graph of relation of

according to the invention and pile penetration h;

Fig. 4 is the physical dimension sketch map of hobboing cutter according to the invention;

Fig. 5 is the graph of relation of hobboing cutter frictional resistance moment according to the invention and native cabin average pressure;

Fig. 6 is the graph of relation of critical minimum pile penetration according to the invention and hobboing cutter frictional resistance moment;

Fig. 7 is one of the graph of relation of critical maximum pile penetration according to the invention and rock uniaxiality strength (the point of a knife width is 20mm);

Fig. 8 is two (nominal load is 250kN) of the graph of relation of critical maximum pile penetration according to the invention and rock uniaxiality strength.

The specific embodiment

Below in conjunction with accompanying drawing the present invention is done further description.

1. principal mode and the reason damaged of hobboing cutter

Through a large amount of investigation and analysis, though the hobboing cutter damage type has variedly in the hard rock, conclude to get up can be divided into: cutter ring damage, damage of bearings, oil sealing damage and other damages etc. four types, and wherein cutter ring eccentric wear, damage of bearings are modal damage types.

2. the mechanical analysis of hobboing cutter damage mechanism

2.1. hobboing cutter force analysis

Shown in Fig. 1 (a), Fig. 1 (b), the external force that hobboing cutter receives in the broken rock process comprises: rock to the active force of blade, rock slag to moments of resistance such as the frictional force of tool surface, bearings etc.Wherein: rock can be decomposed into normal force Fn perpendicular to rock excavation face, be parallel to the cutting force Fr of scar and the lateral force Fs that is parallel to cutter shaft the directed force F t of blade.Usually, the hobboing cutter lateral force is less, omits during calculating and does not remember.The rock slag can be represented with the moment of resistance the effect of hobboing cutter the frictional resistance of tool surface, comprises cutter ring moment of resistance Tq and cutter hub moment of resistance Tt.The moment of resistance that hobboing cutter self rotates generally is called starting torque To.

2.2. hobboing cutter breaks the rock cutting Force Model

The computation model of the broken rock cutting force of relevant disk cutter has experienced by the variation of single factor forecast model to multifactor forecast model, and wherein the CSM model is one of the most famous, that application is the widest model.

2.2.1. cutting Force Model---CSM model

The CSM model is to set up according to the broken rock experimental data of the cutting of hobboing cutter, and through repeatedly improving the model of a comparative maturity that forms, its design formulas is following:

$F_t=\frac{{\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="HSA00000226468200021.png,HSA00000226468200022.png"\; state="\{\{state\}\}">P</figure-callout>}}^0\mathrm{\&phi;<figure-callout\; id="1"\; label="RT"\; filenames="HSA00000226468200021.png"\; state="\{\{state\}\}">RT</figure-callout>}}{1+\mathrm{\&psi;}}---\left(1\right)$

In the formula:

F _t---hobboing cutter is suffered makes a concerted effort kN;

R---hobboing cutter radius, mm;

T---hobboing cutter point of a knife width, mm;

ψ---point of a knife pressure distribution coefficient reduces ψ=0.2～-0.2 with the increase of point of a knife width;

φ---hobboing cutter blade and rock contact angle (radian):

$\mathrm{\&phi;}=\mathrm{Arc}\cos \left(\frac{R-h}{R}\right)---\left(2\right)$

H---the cutterhead penetraction depth that rotates a circle, i.e. pile penetration, mm;

P ⁰---fracture area pressure, relevant with rock strength, hobboing cutter size, cutting edge shape:

${\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="HSA00000226468200021.png,HSA00000226468200022.png"\; state="\{\{state\}\}">P</figure-callout>}}^0=C\sqrt[3]{\frac{S}{\mathrm{\&phi;}\sqrt{\mathrm{RT}}}{{\mathrm{\&sigma;}}_c}^2{\mathrm{\&sigma;}}_t}---\left(3\right)$

In the formula:

σ _c---rock uniaxiality strength, MPa;

σ _t---Tensile Strength of Rock, MPa;

S---point width, mm;

C---be similar to the dimensionless factor at φ angle, C ≈ 2.12.

Formula (1) is the suffered design formulas of making a concerted effort of hobboing cutter, and vertical force and horizontal force are according to computes:

$F_n=F_t\mathrm{Cos}\left(\frac{\mathrm{\&phi;}}{2}\right);$ $F_r=F_t\mathrm{Sin}\left(\frac{\mathrm{\&phi;}}{2}\right)---\left(4\right)$

In the formula:

F _r---hobboing cutter level (tangential) cutting force;

F _n---vertical (normal direction) thrust of hobboing cutter.

This model derives from indoor rock cutting test data, has considered the influence of rock strength, cutter structure size and driving pile penetration etc., and Consideration is more comprehensive, in a lot of engineerings, obtains checking, and it is higher to calculate accuracy rate.

2.2.2.CSM the simplification of cutting Force Model

Can find out the hobboing cutter that obtains after formula (2), (3) substitution formula (1) expression formula of making a concerted effort very complicatedly, and be the transcendental equation about the hobboing cutter pile penetration, can't directly find the solution, and is not easy to use, and needs simplify it for this reason.

In hard rock, pile penetration generally less (being generally less than 30mm) is for commonly used 17 " hobboing cutter (Φ 432mm), hobboing cutter blade that obtains according to formula (2) and the relation curve of rock contact angle φ and pile penetration h are as shown in Figure 2.

Through regression treatment, the both sides relation that obtains is:

φ＝0.0958h ^0.504 (5)

The index of correlation of regression equation is up to 0.998, the average error of this formula only-0.05%, worst error 0.27% satisfies the practical applications requirement.

Equally; simplified; It is as shown in Figure 3 with the relation curve of pile penetration h to obtain

; Through regression treatment, the both sides relation that obtains is:

$\mathrm{Sin}\left(\frac{\mathrm{\&phi;}}{2}\right)={0.0481h}^{0.5}---\left(6\right)$

The average error of following formula only-0.026%, so this simplification is rational.

With formula (5), (6) substitution formula (1), (4), put in order:

$F_t=\frac{0.2094\&times;\mathrm{<figure-callout\; id="1"\; label="CRT"\; filenames="HSA00000226468200021.png"\; state="\{\{state\}\}">CRT</figure-callout>}}{1+\mathrm{\&psi;}}\sqrt[3]{\frac{S}{\sqrt{\mathrm{RT}}}{{\mathrm{\&sigma;}}_c}^2{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="3"\; label="t"\; filenames="HSA00000226468200032.png"\; state="\{\{state\}\}">t</figure-callout>}}}\&times;h^{0.336}---\left(7\right)$

$F_r=\frac{\mathrm{CRT}}{99.3(1+\mathrm{\&psi;})}\sqrt[3]{\frac{S}{\sqrt{\mathrm{RT}}}{{\mathrm{\&sigma;}}_c}^2{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="3"\; label="t"\; filenames="HSA00000226468200032.png"\; state="\{\{state\}\}">t</figure-callout>}}}\&times;h^{0.836}---\left(8\right)$

2.3. the broken rock process rotating torque of hobboing cutter is calculated

2.3.1. the hobboing cutter rotational resistance torque calculates

The rotational resistance torque that the broken rock process of hobboing cutter receives comprises: the rock slag is to cutter ring surface and the moment of resistance of cutter hub skin friction generation and the driving torque (being starting torque) of hobboing cutter itself.

The frictional resistance moment that the cutter ring surface receives the rock slag is:

T _q＝μA _qpR _q (9)

In the formula:

Tq---the frictional resistance moment of the suffered rock slag in cutter ring surface, N.m;

μ---dregs and hobboing cutter skin-friction coefficient, dimensionless;

P---rock slag is to the average pressure (native cabin average pressure) on cutter ring surface, kg/cm ²

Aq---hobboing cutter cutter ring surface area, mm ²

Rq---cutter ring is to the mean radius at hobboing cutter center, mm.

The frictional resistance moment that the cutter hub surface receives the rock slag is:

T _t＝μA _tpR _t (10)

In the formula:

Tt---the frictional resistance moment of the suffered rock slag in cutter hub surface, N.m;

At---hobboing cutter cutter hub surface area, mm ²

Rt---the cutter hub surface is to the mean radius at hobboing cutter center, mm.

Then the rotation drag overall square that receives of the broken rock process of hobboing cutter is:

T _f＝T _q+T _t+T _o (11)

In the formula:

T _f---the drag overall square that the hobboing cutter rotation process receives, N.m;

T _o---the starting torque of hobboing cutter, N.m;

2.3.2. the broken rock driving moment of hobboing cutter is calculated

The active moment Ta that drives the hobboing cutter rotation is provided by the broken suffered cutting force of rock process of hobboing cutter:

T _a＝F _r.R

Formula (8) substitution following formula is got:

$T_a=\frac{C{R}^{2}T}{99.3(1+\mathrm{\&psi;})}\sqrt[3]{\frac{S}{\sqrt{\mathrm{RT}}}{{\mathrm{\&sigma;}}_c}^2{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="3"\; label="t"\; filenames="HSA00000226468200032.png"\; state="\{\{state\}\}">t</figure-callout>}}}\&times;h^{0.836}---\left(12\right)$

In the formula:

Ta---the active moment that hobboing cutter cutting force is produced, N.m; Other symbol is the same.

3. hobboing cutter does not change or the critical pile penetration of transshipping is calculated

3.1. hobboing cutter does not change the critical pile penetration of (eccentric wear)

When the active moment Ta that drives the hobboing cutter rotation less than the suffered rotational resistance torque T of hobboing cutter _fThe time, hobboing cutter can't rotation, promptly produces eccentric wear.So the critical condition of hobboing cutter eccentric wear can be expressed as:

Ta＝Tf (13)

Formula (12) substitution is got:

$\frac{C{R}^{2}T}{99.3(1+\mathrm{\&psi;})}\sqrt[3]{\frac{S}{\sqrt{\mathrm{RT}}}{{\mathrm{\&sigma;}}_c}^2{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="3"\; label="t"\; filenames="HSA00000226468200032.png"\; state="\{\{state\}\}">t</figure-callout>}}}\&times;h^{0.836}=T_f---\left(14\right)$

Transposition is put in order:

$h_{\min }={\left(\frac{{\mathrm{CR}}^{2}T}{99.3(1+\mathrm{\&psi;})T_f}\sqrt[3]{\frac{S}{\sqrt{\mathrm{RT}}}{{\mathrm{\&sigma;}}_c}^2{\mathrm{\&sigma;}}_t}\right)}^{-1.196}---\left(15\right)$

Following formula promptly is the critical minimum pile penetration h that prevents the hobboing cutter eccentric wear _MinDesign formulas.

3.2. the critical pile penetration of hobboing cutter overload (damage)

The suffered load of hobboing cutter (making a concerted effort) is directly proportional with pile penetration, when pile penetration is too big, will cause hobboing cutter overload (being that the suffered load Ft of hobboing cutter is greater than nominal load Fm), makes cutter ring or damage of bearings.So the critical condition of hobboing cutter overload (damage) can be expressed as:

F _t＝F _m (16)

In the formula: Fm---the nominal load of hobboing cutter, kN;

Formula (7) substitution is got:

$\frac{0.2094\&times;\mathrm{<figure-callout\; id="1"\; label="CR\; T"\; filenames="HSA00000226468200021.png"\; state="\{\{state\}\}">CR</figure-callout>}T}{1+\mathrm{\&psi;}}\sqrt[3]{\frac{S}{\sqrt{\mathrm{RT}}}{{\mathrm{\&sigma;}}_c}^2{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="3"\; label="t"\; filenames="HSA00000226468200032.png"\; state="\{\{state\}\}">t</figure-callout>}}}\&times;h^{0.336}=F_m---\left(17\right)$

Transposition is put in order:

$h_{\max }={\left\{\frac{0.2094\&times;\mathrm{CRT}}{(1+\mathrm{\&psi;})F_m}\sqrt[3]{\frac{S}{\sqrt{\mathrm{RT}}}{{\mathrm{\&sigma;}}_c}^2{\mathrm{\&sigma;}}_t}\right\}}^{-2.976}---\left(18\right)$

Following formula promptly is the critical maximum pile penetration h that prevents that the hobboing cutter overload from damaging _MaxDesign formulas.

4. result of calculation and applying examples

4.1. calculating parameter and result

(1) calculating parameter

With on 6 meters left and right sides shield machines of present diameter the most frequently used 17 " hobboing cutter is example, the correlation computations parameter value is (the hobboing cutter structure is seen Fig. 4) as follows, wherein:

Hobboing cutter radius: R=216mm

Hobboing cutter point of a knife width: T=20mm

Point width: S=100mm

Hobboing cutter nominal load: Fm=250kN

Hobboing cutter cutter hub surface area: At=146000mm ²

The hobboing cutter cutter hub to the mean radius at center is: Rt=150mm

Hobboing cutter cutter ring surface area: Aq=187000mm ²

Cutter ring to the mean radius at center is: Rq=190mm

Point of a knife pressure distribution coefficient: ψ=0.15

Rock slag and hobboing cutter skin-friction coefficient: μ=0.1

Compressive strength of rock: σ c=100Mpa

Tensile Strength of Rock: σ t=10Mpa

Hobboing cutter pile penetration: h=10mm/rev

The starting torque of hobboing cutter: T _o=30N.m;

Soil cabin average pressure (as the average pressure of rock slag): p=1.0kg/cm to the cutter ring surface ²

(2) result of calculation

According to formula (7)～(18), relevant parameter result of calculation is following:

Hobboing cutter is suffered makes a concerted effort: Ft=192.8kN

The suffered cutting force of hobboing cutter: Fr=29.3kN

Blade and rock contact angle: φ=17.7 degree

The frictional resistance moment of the suffered rock slag in cutter ring surface: Tq=355.3N.m;

The frictional resistance moment of the suffered rock slag in cutter hub surface: Tt=219N.m;

The drag overall square that the hobboing cutter rotation process receives: Tf=604.3N.m;

The active moment that hobboing cutter cutting force is produced: Ta=6337N.m;

Critical minimum pile penetration: h _Min=0.6mm

Critical maximum pile penetration: h _Max=21.6mm

According to the aforementioned calculation result, tunneling process hobboing cutter pile penetration h should be controlled at 0.6mm～21.6mm scope in such stratum, can guarantee that like this hobboing cutter neither can or not damage because of overload because of not transferring eccentric wear yet.

4.2. application note and example

The aforementioned calculation formula is too numerous and diverse, for ease of The field, design formulas is processed curve map (seeing Fig. 5～8).

4.2.1. critical minimum pile penetration chart usage example

For example: native cabin average pressure (as the average pressure of rock slag) p=1.0kg/cm to the cutter ring surface ², dregs friction factor (dregs and hobboing cutter skin-friction coefficient) μ=0.2, compressive strength of rock (rock uniaxiality strength) σ c=30Mpa, can find critical minimum pile penetration value in two steps from Fig. 5, Fig. 6:

The 1st step: according to native cabin average pressure p=1.0kg/cm ²With dregs coefficientoffriction=0.2, can find hobboing cutter frictional resistance moment (the drag overall square that the hobboing cutter rotation process receives) T by Fig. 5 _f≈ 1170N.m;

The 2nd step: according to frictional resistance moment T _f=1170N.m and compressive strength of rock σ c=30Mpa can find the critical minimum pile penetration h of hobboing cutter by Fig. 6 _Min≈ 5.5mm/rev, promptly pile penetration h must just can prevent the hobboing cutter eccentric wear greater than 5.5mm/rev.

Use Fig. 5, at 6 o'clock, needing explanation:

1. for friction factor that does not have in the chart and compressive strength of rock curve, can search the adjacent curve value earlier, adopt the interpolation method estimation then.

2. the dregs friction factor can be by test determination, general desirable μ=0.15～0.35, and compressive strength of rock σ c can provide with reference to the geotechnical investigation report.

4.2.2. critical maximum pile penetration chart usage example

Example 1: compressive strength of rock σ c=100Mpa, point of a knife width are 20mm, and hobboing cutter maximum allowable bearing capacity (nominal load of hobboing cutter) Fmax is respectively 200kN and 250kN, then can find the critical maximum pile penetration h of hobboing cutter by Fig. 7 _MaxBe respectively 11mm and 21mm, promptly pile penetration h must just can prevent hobboing cutter overload destruction less than analog value.It is thus clear that the hobboing cutter nominal load has very big influence to the critical maximum pile penetration of hobboing cutter.

Example 2: compressive strength of rock σ c=100Mpa, hobboing cutter maximum allowable bearing capacity Fmax=250kN, the point of a knife width is respectively 20mm and 30mm, then can find the critical maximum pile penetration h of hobboing cutter by Fig. 8 _MaxBe respectively 21mm and 8mm, when visible point of a knife width increased, critical maximum pile penetration significantly reduced.So should reduce pile penetration or in time change cutter after the hobboing cutter wearing and tearing.

Use Fig. 7, at 8 o'clock, needing explanation:

1. for the hobboing cutter maximum allowable bearing capacity curve that does not occur in the chart, can search the adjacent curve value earlier, adopt the interpolation method estimation then.

2. 17 " the maximum allowable bearing capacity of hobboing cutter (diameter of phi 432mm) generally is no more than 250kN, desirable Fmax=200kN～250kN under the normal condition.

3. obtain critical minimum pile penetration h according to above each figure _MinWith critical maximum pile penetration h _MaxAfter, should adjust thrust in the tunneling process, make actual pile penetration h be controlled at following scope: hmin＜h＜hmax.

5. conclusion

How effectively reducing the hobboing cutter damage, improving the hobboing cutter efficiency of breaking rock is that shield machine tunnels a main difficult problem that faces in hard rock.The present invention uses the CSM model the broken rock load of hobboing cutter is calculated through broken the stressed of rock process of hobboing cutter analyzed, and has obtained the critical maximum pile penetration that hobboing cutter damages thus; Cutting force according to hobboing cutter has calculated the active moment that drives the hobboing cutter rotation, according to the rock slag the surperficial frictional resistance of hobboing cutter is calculated the hobboing cutter rotational resistance torque again, utilizes both equilibrium relations to obtain the critical minimum pile penetration that hobboing cutter does not change (eccentric wear).For the ease of The field, the aforementioned calculation formula has been processed curve map, and provided applying examples.

The present invention analyzes various factors that influences the broken rock load of hobboing cutter and the various factors that influences critical pile penetration, obtains to draw a conclusion:

(1) the active moment that drives the hobboing cutter rotation is to be produced by the suffered cutting force of the broken rock process of hobboing cutter, and when active moment during less than the suffered rotational resistance torque of hobboing cutter, hobboing cutter can't rotation, promptly produces eccentric wear.

(2) the suffered load of hobboing cutter is directly proportional with pile penetration, when pile penetration is too big, will cause the hobboing cutter overload, makes cutter ring or damage of bearings, and tunneling process should guarantee that the suffered load of hobboing cutter is less than its nominal load.

(3) under other condition same case, the hobboing cutter load is approximated to linear increasing with the increase of point of a knife width, and along with the blade wearing and tearing, the sharp increase of hobboing cutter load is so should in time change the wearing and tearing cutter in the hard rock driving.

(4) the hobboing cutter load increases with rock uniaxiality strength, and the hard rock tunneling process should be noted the variation adjustment driving pile penetration according to rock strength.

(5) critical maximum pile penetration increases with compressive strength of rock and sharply reduces, and in hard rock, should reduce pile penetration, and control thrust with pile penetration, in order to avoid hobboing cutter transships and destroys.

Claims (8)

1. one kind is applied to shield machine reduces the unusual damage of hobboing cutter in tunnel excavating process method, it is characterized in that, may further comprise the steps:

(1) gathers the relevant parameter of hobboing cutter and formation rock, comprise nominal load, rock uniaxiality strength and the Tensile Strength of Rock of hobboing cutter radius, hobboing cutter point of a knife width, point width, point of a knife pressure distribution coefficient, hobboing cutter;

(2) utilize the above-mentioned relevant parameter that collects to calculate the drag overall square that the hobboing cutter rotation process receives;

(3) relevant parameter that combines above-mentioned steps (1), (2) to obtain calculates critical minimum pile penetration and the critical maximum pile penetration of shield machine in tunneling process according to following formula;

Said critical minimum pile penetration h _MinDesign formulas following:

$h_{\mathrm{Min}}={\left(\frac{{\mathrm{CR}}^{2}T}{99.3(1+\mathrm{\&psi;})T_f}\sqrt[3]{\frac{S}{\sqrt{\mathrm{RT}}}{{\mathrm{\&sigma;}}_c}^2{\mathrm{\&sigma;}}_t}\right)}^{-1.196},$ In the formula:

C---dimensionless factor,

R---hobboing cutter radius,

T---hobboing cutter point of a knife width,

ψ---point of a knife pressure distribution coefficient,

S---point width,

σ _c---rock uniaxiality strength,

σ _t---Tensile Strength of Rock,

T _f---the drag overall square that the hobboing cutter rotation process receives;

Said critical maximum pile penetration h _MaxDesign formulas following:

$h_{\mathrm{Max}}={\left\{\frac{0.2094\&times;\mathrm{CRT}}{(1+\mathrm{\&psi;})F_m}\sqrt[3]{\frac{S}{\sqrt{\mathrm{RT}}}{{\mathrm{\&sigma;}}_c}^2{\mathrm{\&sigma;}}_t}\right\}}^{-2.976},$ In the formula:

C---dimensionless factor,

R---hobboing cutter radius,

T---hobboing cutter point of a knife width,

ψ---point of a knife pressure distribution coefficient,

S---point width,

σ _c---rock uniaxiality strength,

σ _t---Tensile Strength of Rock,

F _m---the nominal load of hobboing cutter;

(4) thrust of adjustment shield machine in tunneling process is controlled within the span of critical minimum pile penetration and critical maximum pile penetration its actual pile penetration.

2. in tunnel excavating process, reduce the unusual method of damaging of hobboing cutter according to the said shield machine that is applied to of claim 1, it is characterized in that the drag overall square T that said hobboing cutter rotation process receives _fDesign formulas be:

T _f＝T _q+T _t+T _o

In the formula:

Tq---the frictional resistance moment of the suffered rock slag in cutter ring surface;

Tt---the frictional resistance moment of the suffered rock slag in cutter hub surface;

T _o---the starting torque of hobboing cutter.

3. in tunnel excavating process, reduce the unusual method of damaging of hobboing cutter according to the said shield machine that is applied to of claim 2, it is characterized in that the design formulas of the frictional resistance moment Tq of the suffered rock slag in said cutter ring surface is:

T _q＝μA _qpR _q

In the formula:

μ---dregs and hobboing cutter skin-friction coefficient;

P---rock slag is to the average pressure on cutter ring surface;

Aq---hobboing cutter cutter ring surface area;

Rq---cutter ring is to the mean radius at hobboing cutter center.

4. in tunnel excavating process, reduce the unusual method of damaging of hobboing cutter according to the said shield machine that is applied to of claim 2, it is characterized in that the design formulas of the frictional resistance moment Tt of the suffered rock slag in said cutter hub surface is:

T _t＝μA _tpR _t

In the formula:

μ---dregs and hobboing cutter skin-friction coefficient;

P---rock slag is to the average pressure on cutter ring surface;

At---hobboing cutter cutter hub surface area;

Rt---the cutter hub surface is to the mean radius at hobboing cutter center.

5. one kind is applied to shield machine reduces the unusual damage of hobboing cutter in tunnel excavating process method, it is characterized in that, comprises following concrete steps:

(1) gathers the relevant parameter of hobboing cutter and formation rock, comprise the nominal load of native cabin average pressure, dregs friction factor, compressive strength of rock and hobboing cutter;

(2) according to the graph of relation of native cabin average pressure and frictional resistance moment, the drag overall square that the hobboing cutter rotation process receives under the dregs friction factor that obtains in above-mentioned steps (1), to gather of tabling look-up, i.e. frictional resistance moment;

(3) according to the graph of relation of critical minimum pile penetration and frictional resistance moment, the critical minimum pile penetration of hobboing cutter under the compressive strength of rock that obtains in above-mentioned steps (1), to gather of tabling look-up;

(4) according to the graph of relation of critical maximum pile penetration and compressive strength of rock, the critical maximum pile penetration of hobboing cutter under the nominal load that obtains the hobboing cutter of collection in above-mentioned steps (1) of tabling look-up;

(5) thrust of adjustment shield machine in tunneling process is controlled within the span of critical minimum pile penetration and critical maximum pile penetration its actual pile penetration.

6. one kind is applied to shield machine reduces the unusual damage of hobboing cutter in tunnel excavating process method, it is characterized in that, comprises following concrete steps:

(1) gathers the relevant parameter of hobboing cutter and formation rock, comprise the point of a knife width of native cabin average pressure, dregs friction factor, compressive strength of rock and hobboing cutter;

(2) according to the graph of relation of native cabin average pressure and frictional resistance moment, the drag overall square that the hobboing cutter rotation process receives under the dregs friction factor that obtains in above-mentioned steps (1), to gather of tabling look-up, i.e. frictional resistance moment;

(3) according to the graph of relation of critical minimum pile penetration and frictional resistance moment, the critical minimum pile penetration of hobboing cutter under the compressive strength of rock that obtains in above-mentioned steps (1), to gather of tabling look-up;

(4) according to the graph of relation of critical maximum pile penetration and compressive strength of rock, the critical maximum pile penetration of hobboing cutter under the point of a knife width that obtains the hobboing cutter of collection in above-mentioned steps (1) of tabling look-up;

(5) thrust of adjustment shield machine in tunneling process is controlled within the span of critical minimum pile penetration and critical maximum pile penetration its actual pile penetration.

7. in tunnel excavating process, reduce the unusual method of damaging of hobboing cutter according to claim 5 or the 6 said shield machines that are applied to; It is characterized in that; In the critical minimum pile penetration of said step (3) and the graph of relation of frictional resistance moment; If the dregs friction factor that does not collect or the curve of compressive strength of rock are at first searched adjacent curve values, estimate the frictional resistance moment or the critical minimum pile penetration of relevant parameter value then through interpolation method.

8. in tunnel excavating process, reduce the unusual method of damaging of hobboing cutter according to claim 5 or the 6 said shield machines that are applied to; It is characterized in that; In the critical maximum pile penetration of said step (4) and the graph of relation of compressive strength of rock; If the curve of the nominal load of the hobboing cutter that does not collect or point of a knife width is at first searched adjacent curve values, estimate the critical maximum pile penetration of relevant parameter value then through interpolation method.

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