CN102734556A - Trenchless construction method for power pipes - Google Patents

Abstract

The invention discloses a trenchless construction method for power pipes, and belongs to the field of construction. The trenchless construction method for the power pipes comprises a horizontal directional drilling construction method. The trenchless construction method for the power pipes at least comprises the following steps of: drilling a guide hole according to a design curve; forming a composite structure of a power pipe bundle by using a plurality of power pipes; pulling the power pipe bundle back into a guide hole along the guide hole to finish pipeline crossing work, wherein in a pullback process, a multi-pipe pullback effect is considered, the power pipe bundle is regarded as a whole, and water injection pullback is not considered; on the premises of considering the multi-pipe pullback effect, regarding the power pipe bundle as the whole and considering the water injection pullback in the pullback process, the total tension of the pipe bundle of the power pipes at each point along a drilling track in a pullback process, the average axial tension stress corresponding to each pipeline and the tension safety condition of a pullback pipeline are determined; after the power pipe bundle is pulled back in a position and when compaction grouting is performed, the grouting pressure is considered as an external pressure of the pipeline; and by the method, the safety in power pipe construction is ensured. The trenchless construction method for the power pipes can be widely used in the field such as the design, the construction and the management of power pipelines.

Description

A kind of non-excavating construction method of electric power comb

Technical field

The invention belongs to construction field, relate in particular to a kind of laying method that is used for the electric power comb.

Background technique

Along with the fast development and the quickening of urbanization process of urban economy, the power engineering construction project is increasing.Need not set up shaft tower and lead on the road surface, not take up an area of space of planes, be easy to keep the power cable engineering of appearance of the city neat appearance more and more yet.

The construction of normal cable engineering all is that fluting is laid power pipe, causes to make the disgustful road of citizen " slide fastener phenomenon ".In building the power channel process, run into unavoidably and can't excavate node such as all kinds of municipal pipelines point of intersection, highway, railway, bridge, river course and the above ground structure etc. that technology is passed through simultaneously by tradition.Therefore, the conventional heavy excavation construction technology needs of incompatibility urban development more and more.

An emerging technology---trenchless technology has obtained application more and more widely in the power pipe engineering in recent years.Though trenchless technology is started late, to popularize along with what use, no matter in theory trenchless technology still aspect construction process, has all had the development of advancing by leaps and bounds.Though trenchless technology comes out first with high-tech advantage, also there are many direct and indirect risks in trenchless technology in construction.Because the face of land down construction has scene property, complexity, discontinuity and comprehensive feature, be prone to cause damage or the like the problem of surface buildings depression, roadbed subsidence cracking, underground structure and underground existing pipeline in the construction.

Because the horizontal orientation technology of creeping into has many advantages with respect to the method for tradition excavation, make it more and more widely in the application of laying the urban electric power pipeline.

Power pipe construction exists multitube to make up back to drag and construction characteristic such as compaction grouting; Not only make back the resistance when dragging increase; And the grouting pressure that acts on the pipeline outer wall can reduce pipeline critical external compressive resistance ability simultaneously, drags construction that significant difference is arranged with returning of single pipe.

Be to guarantee the safety and the quality of engineering of pipeline self, the pull-back force during reply is constructed before going back to the hauling pipe road calculates, and the electric power comb is carried out force analysis, thus guarantee pipeline return drag with mortar depositing construction in safety.

Summary of the invention

Technical problem to be solved by this invention provides a kind of non-excavating construction method of electric power comb; Its consideration multitube returns and drags effect; Regard the tube bank of comb as whole; Utilize the equivalent redius of tube bank and the equivalent friction factor of tube bank and hole wall, ASTM pull-back force computational methods commonly used are improved, make its more suitable power pipeline pull-back force calculating; Simultaneously with grouting pressure as the suffered pressure outside of pipeline, the stress of pipeline when analyzing slip casting, thus guarantee pipeline return drag with mortar depositing construction in safety.

Technological scheme of the present invention is: the non-excavating construction method that a kind of electric power comb is provided; Comprise that horizontal orientation creeps into construction method; It is characterized in that described non-excavating construction method comprises the following steps: to bore a pilot hole according to design curve earlier at least, described pilot hole is by the point that buries, first inclination section that connect successively; Horizontal segment, second inclination section and unearthed point constitute; The composite structure of many electric power combs being formed an electric power comb tube bank; Return electric power comb tube bank along pilot hole and to be dragged in the pilot hole, accomplish pipeline and pass through work; Wherein, drag in the process returning, to consider that multitube returns to drag effect, to regard the tube bank of electric power comb as whole, and not consider that water filling is returned and drag; Putting before this, confirming that the electric power comb drags in the process along the suffered total pulling force of the tube bank of drilling track each point, the average every corresponding axial tension stress of pipeline and goes back to the hauling pipe road and drawn safety condition returning; The electric power comb is restrained back and is dragged when carrying out compaction grouting after in place, takes grouting pressure into account as the suffered external pressure of pipeline; Through said method, guarantee the electric power comb return drag with mortar depositing construction in safety.

Further, after described guiding hole drill is intact, pilot hole is carried out reaming; Return electric power comb tube bank along the pilot hole that has enlarged and to be dragged in the pilot hole, accomplish pipeline and pass through work.

Concrete, its said electric power comb drags in the process along the suffered total pulling force parameter of the tube bank of pilot hole track each point returning, and confirms according to following representation:

$T_1=e^{{\mathrm{\&upsi;}}_a\mathrm{\&alpha;}}\left[{\mathrm{\&upsi;}}_a{\mathrm{\&omega;}}_a(L_1+{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">L</figure-callout>}}_2+{\mathrm{<figure-callout\; id="3"\; label="L"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">L</figure-callout>}}_3+L_4)\right]$

${\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">T</figure-callout>}}_2=e^{{\mathrm{\&upsi;}}_b\mathrm{\&alpha;}}(T_1+T_h+{\mathrm{\&upsi;}}_b|{\mathrm{\&omega;}}_b|{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">L</figure-callout>}}_2+{\mathrm{\&omega;}}_{b}H-{\mathrm{\&upsi;}}_a{\mathrm{\&omega;}}_a{L}_2{e}^{{\mathrm{\&upsi;}}_a\mathrm{\&alpha;}})$

${\mathrm{<figure-callout\; id="3"\; label="T"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">T</figure-callout>}}_3=T_2-e^{{\mathrm{\&upsi;}}_b\mathrm{\&alpha;}}\left({\mathrm{\&upsi;}}_a{\mathrm{\&omega;}}_a{L}_3{e}^{{\mathrm{\&upsi;}}_a\mathrm{\&alpha;}}\right)+T_h+{\mathrm{\&upsi;}}_b\left|{\mathrm{\&omega;}}_b\right|{\mathrm{<figure-callout\; id="3"\; label="L"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">L</figure-callout>}}_3$

${\mathrm{<figure-callout\; id="4"\; label="T"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">T</figure-callout>}}_4=e^{{\mathrm{\&upsi;}}_a\mathrm{\&beta;}}[{\mathrm{<figure-callout\; id="3"\; label="T"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">T</figure-callout>}}_3+T_h+{\mathrm{\&upsi;}}_b|{\mathrm{\&omega;}}_b|L_4-{\mathrm{\&omega;}}_{b}H-e^{{\mathrm{\&upsi;}}_a\mathrm{\&alpha;}}\left({\mathrm{\&upsi;}}_a{\mathrm{\&omega;}}_a{L}_4{e}^{{\mathrm{\&upsi;}}_a\mathrm{\&alpha;}}\right)]$

$T_h=P_h\frac{\mathrm{\&pi;}}{8}(D_h^2-D_m^2)$

$D_m=\sqrt{n}D$

${\mathrm{\&omega;}}_a=\frac{1.06\mathrm{n\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">D</figure-callout>}}^2{\mathrm{\&gamma;}}_a(\mathrm{DR}-1)}{{\mathrm{<figure-callout\; id="2"\; label="DR"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">DR</figure-callout>}}^2}$

${\mathrm{\&omega;}}_b=\frac{\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">D</figure-callout>}}^2{\mathrm{\&gamma;}}_b}{4}-\frac{1.06\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">D</figure-callout>}}^2{\mathrm{\&gamma;}}_a(\mathrm{DR}-1)}{{\mathrm{<figure-callout\; id="2"\; label="DR"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">DR</figure-callout>}}^2}$

Wherein, T ₁Locate to restrain total pull-back force (KN) for burying; T ₂It is the total pull-back force (KN) of first inclination section destination county tube bank; T ₃It is the total pull-back force (KN) of second inclination section starting point place tube bank; T ₄Be the total pull-back force (KN) of unearthed point place tube bank; L ₁Additional length (m) for tube bank; L ₂Be bury the some horizontal length (m) of deflecting terminal point of tube bank; L ₃Be tube bank horizontal section length (m); L ₄Be the horizontal length (m) of tube bank horizontal segment terminal point to unearthed point; H is the height (m) of tube bank apart from ground; υ _aFor the friction factor of tube bank, get 0.5 usually with ground; υ _bFor the friction factor of tube bank in the hole, get 0.3 usually, multitube returns when dragging between 0.3 ~ 0.5, and maximum is got υ _aω _aBe the total weight (KN/m) of unit length blank pipe bundle; ω _bBe unit length tube bank net buoyancy (KN/m) upwards; The penetrating angle (rad) of tube bank when α is back to drag; The unearthed angle (rad) of tube bank when β is back to drag; γ _aWeight for the per unit volume pipeline material; γ _bWeight (KN/m for mud in the per unit volume annular space and landwaste mixture ³); P _hFor the kinetic pressure of annular space mud, get 0.035 ~ 0.070MPa usually to pipeline; D is the external diameter (m) of single pipe; D _hBe bore diameter (m); D _mBe diameter (m) behind the tube bank area equivalent; DR is the ratio of single pipe external diameter and wall thickness; N is for comprising the number of pipeline in the tube bank.

Concrete, its described average every corresponding axial tension stress parameter of pipeline, adopt following representation to confirm:

${\mathrm{\&sigma;}}_x=\frac{T_x}{\mathrm{n\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">D</figure-callout>}}^2}\frac{{\mathrm{<figure-callout\; id="2"\; label="DR"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">DR</figure-callout>}}^2}{\mathrm{DR}-1}$

Wherein, σ _xBe axial tension stress (MPa) in the average every pipeline of pilot hole respective point; T _xBe the total pull-back force (KN) of pilot hole respective point tube bank.

Concrete, its described time hauling pipe road drawn the security parameter condition, must satisfy following condition:

σ _p<σ _allow

Wherein, σ _p=σ _x+ σ _a

${\mathrm{\&sigma;}}_a=\frac{E_{24}D}{2R_{\mathrm{avg}}}$

$R_{\mathrm{avg}}=\frac{2H}{{\mathrm{\&theta;}}^2}$

σ _pBending section interior conduit maximum tension stress (MPa) for the respective point place; σ _aBe respective point place bending section interior conduit maximum stress in bend (MPa); E ₂₄Be the Young's modulus (MPa) in the pipeline 24 hours; R _AvgBe the mean radius of curvature (m) of pipeline in the hole; θ is penetrating angle or unearthed angle (rad) of pipeline.

Concrete, when the tension checking computations are carried out in described tube bank, the allowable tensile stress parameter of every pipeline in the tube bank, must less than its axial tension stress and flexural stress and, that is: σ _Allow<σ _x+ σ _a

Wherein, C _AllowBe the allowable tensile stress of every pipeline, σ _xBe axial tension stress (MPa) in the average every pipeline of pilot hole respective point, σ _aBe respective point place bending section interior conduit maximum stress in bend (MPa).

Concrete, when carrying out said compaction grouting, the suffered pressure outside parameter of pipeline adopts following representation to confirm:

P _net=p+γ _csH+P _ch-P _i

Wherein, P is grouting pressure (MPa); γ _CsWeight (KN/m for the per unit volume cement slurry ³); H is the thickness (m) of last overburden layer; P _ChFor the kinetic pressure (MPa) of cement slurry, be approximately equal to P to pipeline _hP _hFor annular space mud acts on the kinetic pressure (MPa) on the pipeline; P _iFor acting on the internal pressure (MPa) on the pipeline.

Above-mentioned method of construction and each parameter are confirmed representation, are applicable to the administrative standard of design to electric power comb trenchless engineering, construction, tubing aspect, also are applicable to corresponding construction Supervision standard.

Compare with existing technology, advantage of the present invention is:

1. trenchless technology is combined with laying of power cable; Be the safety of assurance pipeline self and the quality of engineering; Pull-back force before going back to the hauling pipe road in the reply construction calculates, and the electric power comb is carried out force analysis, thus guarantee pipeline return drag with mortar depositing construction in safety.

2. current power transmission and transformation comb trenchless engineering method of construction has been carried out effectively replenishing, also standard management foundation and the management behaviors of management personnel in the construction of non-excavation laying power pipe.

Description of drawings

Fig. 1 is that horizontal directional drill passes through the track schematic representation;

Fig. 2 is hoop amount of deflection percentage and penalty coefficient curve.

Embodiment

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

Among Fig. 1, pilot hole buries a little by what connect successively that intersection point 3, the second inclination section L4 and the unearthed point 4 of intersection point 2, horizontal segment L3, horizontal segment and second inclination section of 1, the first inclination section L2, first inclination section and horizontal segment constitute.

Electric power comb and general horizontal directional drill pass through maximum difference performance both ways: the one, and multitube makes up back and drags; Not only cause the increase of pipeline net buoyancy; And cause pipeline directly to contact thus with hole wall; Cause friction factor to increase, the multitube effect also will change the suffered fluid resistance of pipeline, and the suffered pull-back force of pipeline will be heightened ^[7]The 2nd, pipeline will carry out compaction grouting at annular space after returning and dragging, and can apply an additional pressure outside to pipeline, thereby needs to analyze grouting pressure, makes it the anti-outer rupture pressure that squeezes less than pipeline.

So the non-excavating construction method that the present technique scheme provides comprises the following steps: at least

Bore a pilot hole according to design curve earlier, described pilot hole is by the point that buries, first inclination section that connect successively; Horizontal segment, second inclination section and unearthed point constitute;

The composite structure of many electric power combs being formed an electric power comb tube bank;

Return electric power comb tube bank along pilot hole and to be dragged in the pilot hole, accomplish pipeline and pass through work;

Wherein, drag in the process returning, to consider that multitube returns to drag effect, to regard the tube bank of electric power comb as whole, and not consider that water filling is returned and drag;

Putting before this, confirming that the electric power comb drags in the process along the suffered total pulling force of the tube bank of drilling track each point, the average every corresponding axial tension stress of pipeline and goes back to the hauling pipe road and drawn safety condition returning;

The electric power comb is restrained back and is dragged when carrying out compaction grouting after in place, takes grouting pressure into account as the suffered external pressure of pipeline;

Through said method, guarantee the electric power comb return drag with mortar depositing construction in safety.

Further, after described guiding hole drill is intact, pilot hole is carried out reaming; Return electric power comb tube bank along the pilot hole that has enlarged and to be dragged in the pilot hole, accomplish pipeline and pass through work.

Concrete, the present technique scheme is considered that multitube returns and is dragged effect, regards the tube bank of comb as whole, and does not consider that water filling is returned and drag; The ASTM method is calculated the formula of pull-back force and is revised, obtain the electric power comb and return and drag in the process that to restrain suffered total pulling force along drilling track each point shown in Figure 1 following:

$T_1=e^{{\mathrm{\&upsi;}}_a\mathrm{\&alpha;}}\left[{\mathrm{\&upsi;}}_a{\mathrm{\&omega;}}_a(L_1+{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">L</figure-callout>}}_2+{\mathrm{<figure-callout\; id="3"\; label="L"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">L</figure-callout>}}_3+L_4)\right]---\left(1\right)$

${\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">T</figure-callout>}}_2=e^{{\mathrm{\&upsi;}}_b\mathrm{\&alpha;}}(T_1+T_h+{\mathrm{\&upsi;}}_b|{\mathrm{\&omega;}}_b|{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">L</figure-callout>}}_2+{\mathrm{\&omega;}}_{b}H-{\mathrm{\&upsi;}}_a{\mathrm{\&omega;}}_a{L}_2{e}^{{\mathrm{\&upsi;}}_a\mathrm{\&alpha;}})---\left(2\right)$

${\mathrm{<figure-callout\; id="3"\; label="T"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">T</figure-callout>}}_3=T_2-e^{{\mathrm{\&upsi;}}_b\mathrm{\&alpha;}}\left({\mathrm{\&upsi;}}_a{\mathrm{\&omega;}}_a{L}_3{e}^{{\mathrm{\&upsi;}}_a\mathrm{\&alpha;}}\right)+T_h+{\mathrm{\&upsi;}}_b\left|{\mathrm{\&omega;}}_b\right|L_3---\left(3\right)$

${\mathrm{<figure-callout\; id="4"\; label="T"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">T</figure-callout>}}_4=e^{{\mathrm{\&upsi;}}_a\mathrm{\&beta;}}[{\mathrm{<figure-callout\; id="3"\; label="T"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">T</figure-callout>}}_3+T_h+{\mathrm{\&upsi;}}_b|{\mathrm{\&omega;}}_b|L_4-{\mathrm{\&omega;}}_{b}H-e^{{\mathrm{\&upsi;}}_a\mathrm{\&alpha;}}\left({\mathrm{\&upsi;}}_a{\mathrm{\&omega;}}_a{L}_4{e}^{{\mathrm{\&upsi;}}_a\mathrm{\&alpha;}}\right)]---\left(4\right)$

$T_h=P_h\frac{\mathrm{\&pi;}}{8}(D_h^2-D_m^2)---\left(5\right)$

$D_m=\sqrt{n}D---\left(6\right)$

${\mathrm{\&omega;}}_a=\frac{1.06\mathrm{n\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">D</figure-callout>}}^2{\mathrm{\&gamma;}}_a(\mathrm{DR}-1)}{{\mathrm{DR}}^2}---\left(7\right)$

${\mathrm{\&omega;}}_b=\frac{\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">D</figure-callout>}}^2{\mathrm{\&gamma;}}_b}{4}-\frac{1.06\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">D</figure-callout>}}^2{\mathrm{\&gamma;}}_a(\mathrm{DR}-1)}{{\mathrm{DR}}^2}---\left(8\right)$

Wherein, T ₁---the total pull-back force (KN) of Fig. 1 mid point 1 place tube bank;

T ₂---the total pull-back force (KN) of Fig. 1 mid point 2 places tube bank;

T ₃---the total pull-back force (KN) of Fig. 1 mid point 3 places tube bank;

T ₄---the total pull-back force (KN) of Fig. 1 mid point 4 places tube bank;

L ₁---the additional length (m) of tube bank;

L ₂---tube bank is buried and is a little arrived the horizontal length (m) of deflecting terminal point;

L ₃---tube bank horizontal section length (m);

L ₄---tube bank horizontal segment terminal point is to the horizontal length (m) of unearthed point;

H---tube bank is apart from the height (m) on ground;

υ _a---the friction factor on tube bank and ground, get 0.5 usually;

υ _b---the friction factor of tube bank in the hole, get 0.3 usually, multitube returns when dragging between 0.3 ~ 0.5, and maximum is got υ _a

ω _a---the weight (KN/m) that unit length blank pipe bundle is total;

ω _b---unit length tube bank net buoyancy (KN/m) upwards;

α---return the penetrating angle (rad) of tube bank when dragging;

β---go back to the unearthed angle (rad) of tube bank when dragging;

γ _a---the weight of per unit volume pipeline material;

γ _b---the weight (KN/m of mud and landwaste mixture in the per unit volume annular space ³);

P _h---annular space mud is got 0.035 ~ 0.070MPa usually to the kinetic pressure of pipeline ^[1]

The external diameter of D---single pipe (m);

D _h-bore diameter (m);

D _m---diameter (m) behind the tube bank area equivalent;

DR---the ratio of single pipe external diameter and wall thickness;

N---comprise the number of pipeline in the tube bank.

Pull-back force by the tube bank each point can get on average every corresponding axial tension stress formula of pipeline:

${\mathrm{\&sigma;}}_x=\frac{T_x}{\mathrm{n\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">D</figure-callout>}}^2}\frac{{\mathrm{<figure-callout\; id="2"\; label="DR"\; filenames="HDA00001772637000011.png"\; state="\{\{state\}\}">DR</figure-callout>}}^2}{\mathrm{DR}-1}---\left(9\right)$

σ _x---axial tension stress (MPa) in the average every pipeline of respective point;

T _xThe pull-back force (KN) that the tube bank of-respective point is total.

Pipeline produces flexural stress at bending section owing to self is crooked ^[10], flexural stress and the suffered maximum stress of axial tension stress stack back pipeline can be represented with following formula:

σ _p=σ _x+σ _a (10)

${\mathrm{\&sigma;}}_a=\frac{E_{24}D}{2R_{\mathrm{avg}}}---\left(11\right)$

$R_{\mathrm{avg}}=\frac{2H}{{\mathrm{\&theta;}}^2}---\left(12\right)$

Wherein, σ _p---the bending section interior conduit maximum tension stress (MPa) at respective point place;

σ _a---respective point place bending section interior conduit maximum stress in bend (MPa);

E ₂₄---the Young's modulus (MPa) in the pipeline 24 hours;

R _Avg---the mean radius of curvature (m) of pipeline in the hole;

The penetrating angle of θ---pipeline or unearthed angle (rad);

In sum, can go back to the hauling pipe road is drawn safety condition to be: σ _p<σ _Allow(allowable tensile stress of pipeline material).

Be in underground pipeline no matter in the process that still operation is installed, all can receive effect in outer year of various combination.Pipeline can produce circumferential pressure in tube wall under external load function, initial ring is to deflection thus.The load that makes pipeline produce the hoop deflection has pressure outside, bending load and buoyancy etc. such as last overburden layer pressure and mud pressure.

Pipeline returns the stability that pressure outside suffered when dragging depends primarily on hole wall, returns that pipeline is surrounded by annular space mud and detrital mixture when dragging, and the similar bury of the character of this mixture is not considered its supporting effect to pipeline usually during calculating.

Therefore the pressure that earthing pressure, groundwater pressure and live load produce under the condition that hole wall caves in there being the suffered pressure outside of pipeline; Drag the pressure outside that receives to be mainly mud pressure and hydrodynamic pressure and return at the complete boring interior conduit of hole wall, formula is following:

The suffered external pressure formula of pipeline during hole wall collapse:

P _net=γ _sH _s+P _w+P _l-P _i (13)

The suffered external pressure formula of pipeline when hole wall is stablized:

P _net=γ _bH+P _h-P _i (14)

P _Net---the pressure outside (MPa) that pipeline is suffered;

γ _s---go up the weight (KN/m of overburden layer per unit volume ³);

H _sThe thickness (m) of-last overburden layer;

P _w---the pressure outside (MPa) of groundwater effect on pipeline;

P _l-live load acts on the pressure outside (MPa) on the pipeline;

P _i-act on the internal pressure (MPa) on the pipeline;

P _h---annular space mud acts on the kinetic pressure (MPa) on the pipeline.

Generally the pipe ring more than phreatic surface reach 20% to deflection will unstability, be in pipe ring below the phreatic surface and reach 15% to deflection unstability will take place.Pipe ring to surrender and destruction be the key factor of decision pipe safety, thereby must carry out the critical external compressive resistance failure analysis to pipeline.

The hoop amount of deflection percentage formula of pipeline is under the external pressure effect:

$\%\mathrm{\&Delta;D}=\frac{0.0125P_{\mathrm{net}}}{\frac{E_L}{12{(\mathrm{DR}-1)}^3}}\&times;100---\left(15\right)$

The hoop amount of deflection percentage formula of pipeline under the floating function:

$\%\mathrm{\&Delta;}{D}_b=\frac{0.088{\mathrm{\&gamma;}}_{b}D}{E_L}\frac{{(\mathrm{DR}-1)}^4}{\mathrm{DR}}---\left(16\right)$

E _L---the long-run elasticity modulus (MPa) of pipeline.

Usually get under the external pressure effect and amount of deflection percentage maximum value calculation under the floating function.

Afterwards carry out compaction grouting for the electric power comb owing to returning to drag, also need consider the influence of grouting pressure at annular space.Therefore the failure analysis of electric power comb critical external compressive resistance comprises two-part: the one, and return and drag the critical external compressive resistance failure analysis in the process, the 2nd, the critical external compressive resistance failure analysis in the slip casting process.

Because the stable case of hole wall is different, the external pressure combination difference that pipeline is suffered selects formula (13) or (14) to calculate the suffered external pressure of pipeline according to actual conditions in the actual checking computations.

According to the Levy formula, the critical surrender pressure outside that gets pipeline is:

$P_u=\frac{2E_L}{1-{\mathrm{\&mu;}}^2}{\left(\frac{1}{\mathrm{DR}-1}\right)}^3\frac{f_o}{N}---\left(17\right)$

The Poisson's ratio of μ---pipeline material;

f _o-ovality penalty coefficient;

N---safety coefficient gets 2 usually.

Ovality penalty coefficient f ₀The maximum loop that can pass through to calculate pipeline is tried to achieve by hoop amount of deflection percentage shown in Figure 2 and penalty coefficient curve to amount of deflection percentage % Δ D.

The critical external compressive resistance yield factor of safety of pipeline:

When safety coefficient greater than 1 the time, pipeline can not surrendered under external pressure; Otherwise then surrender.

Return in reality and to drag in the process, pipeline often receives axial tension and pressure outside effect simultaneously.Because the effect of axial tension can make pipeline produce contraction strain radially, this effect can reduce the critical external compressive resistance performance of pipeline.Therefore calculate critical rupture pressure and need multiply by the axial stress reduction coefficient the critical pressure that the Levy formula calculates.

The critical destruction pressure outside of pipeline formula:

$P_{\mathrm{cr}}=\frac{2E_{24}}{1-{\mathrm{\&mu;}}^2}{\left(\frac{1}{\mathrm{DR}-1}\right)}^3\frac{f_o{f}_R}{N}---\left(18\right)$

$f_R=\sqrt{[5.57-{(\frac{{\mathrm{\&sigma;}}_x}{2{\mathrm{\&sigma;}}_{\mathrm{sp}}}+1.09)}^2]}-1.09---\left(19\right)$

${\mathrm{\&sigma;}}_{\mathrm{sp}}={\mathrm{\&sigma;}}_{\mathrm{allow}}-\frac{\mathrm{ED}}{2R_{\mathrm{avg}}}---\left(20\right)$

f _R---the axial stress reduction coefficient;

σ _Allow---the allowable tensile stress (MPa) of pipeline material;

σ _Sp---pipe safety returns the tensile stress (MPa) of dragging.

The pipeline critical external compressive resistance destroys safety coefficient:

When safety coefficient greater than 1 the time, pipeline can not destroy under external pressure; Otherwise then destroy.The suffered pressure outside of pipeline during compaction grouting:

P _net=p+γ _csH+P _ch-P _i (21)

P---grouting pressure (MPa);

γ _Cs---the weight (KN/m of per unit volume cement slurry ³);

P _Ch---cement slurry is approximately equal to P to the kinetic pressure (MPa) of pipeline _h

Critical external compressive resistance failure analysis formula during compaction grouting and step and return when dragging basic identically, just external pressure changes.With above-mentioned external pressure formula substitution formula (17), the critical external compressive resistance yield factor of safety and the critical external compressive resistance that calculate pipeline respectively destroy safety coefficient, and whether the checking computations grouting pressure satisfies safety requirement.

In sum; (1) the electric power comb makes the suffered mud resistance of pipeline increase because multitube makes up back and drags on the one hand, on the other hand along with number of tubes increases; Restraining suffered gravity or net buoyancy increases; Tube bank directly contacts with hole wall, thereby increases its suffered surface friction drag, and this all makes pull-back force heighten.

When (2) the tension checking computations are carried out in tube bank, should make every pipeline wherein allowable tensile stress must less than its axial tension stress and flexural stress with, i.e. σ _Allow<σ _x+ σ _a

(3) pipeline produces contraction strain radially under external pressure effect and axial tension effect, and this effect can reduce the critical external compressive resistance performance of pipeline, will multiply by the axial stress reduction coefficient so calculate the critical destruction pressure outside of pipeline.

(4) the electric power comb returns to drag and will carry out compaction grouting after in place, take grouting pressure into account as the suffered external pressure of pipeline, therefore will be respectively to pipeline return drag in the process with the slip casting process in critical external compressive resistance destroy and analyze.

Because the consideration multitube returns and drags effect in the technological scheme of the present invention; Regard the tube bank of electric power comb as whole; Utilize the equivalent redius of tube bank and the equivalent friction factor of tube bank and hole wall, ASTM pull-back force computational methods commonly used are improved, make its more suitable power pipeline pull-back force calculating; Simultaneously with grouting pressure as the suffered pressure outside of pipeline, the stress of pipeline when analyzing slip casting, thus guarantee pipeline return drag with mortar depositing construction in safety.

The present invention can be widely used in design, construction and the management field of power pipe.

Claims (8)

1. the non-excavating construction method of an electric power comb comprises that horizontal orientation creeps into construction method, it is characterized in that described non-excavating construction method comprises the following steps: at least

Bore a pilot hole according to design curve earlier, described pilot hole is by the point that buries, first inclination section that connect successively; Horizontal segment, second inclination section and unearthed point constitute;

The composite structure of many electric power combs being formed an electric power comb tube bank;

Return electric power comb tube bank along pilot hole and to be dragged in the pilot hole, accomplish pipeline and pass through work;

Wherein, drag in the process returning, to consider that multitube returns to drag effect, to regard the tube bank of electric power comb as whole, and not consider that water filling is returned and drag;

Putting before this, confirming that the electric power comb drags in the process along the suffered total pulling force of the tube bank of drilling track each point, the average every corresponding axial tension stress of pipeline and goes back to the hauling pipe road and drawn safety condition returning;

The electric power comb is restrained back and is dragged when carrying out compaction grouting after in place, takes grouting pressure into account as the suffered external pressure of pipeline;

Through said method, guarantee the electric power comb return drag with mortar depositing construction in safety.

2. according to the non-excavating construction method of the described electric power comb of claim 1, it is characterized in that after described guiding hole drill is intact, pilot hole being carried out reaming; Return electric power comb tube bank along the pilot hole that has enlarged and to be dragged in the pilot hole, accomplish pipeline and pass through work.

3. according to the non-excavating construction method of the described electric power comb of claim 1, it is characterized in that said electric power comb drags in the process along the suffered total pulling force parameter of the tube bank of pilot hole track each point returning, and confirms according to following representation:

$T_1=e^{{\mathrm{\&upsi;}}_a\mathrm{\&alpha;}}\left[{\mathrm{\&upsi;}}_a{\mathrm{\&omega;}}_a(L_1+L_2+L_3+L_4)\right]$

$T_2=e^{{\mathrm{\&upsi;}}_b\mathrm{\&alpha;}}(T_1+T_h+{\mathrm{\&upsi;}}_b|{\mathrm{\&omega;}}_b|L_2+{\mathrm{\&omega;}}_{b}H-{\mathrm{\&upsi;}}_a{\mathrm{\&omega;}}_a{L}_2{e}^{{\mathrm{\&upsi;}}_a\mathrm{\&alpha;}})$

$T_3=T_2-e^{{\mathrm{\&upsi;}}_b\mathrm{\&alpha;}}\left({\mathrm{\&upsi;}}_a{\mathrm{\&omega;}}_a{L}_3{e}^{{\mathrm{\&upsi;}}_a\mathrm{\&alpha;}}\right)+T_h+{\mathrm{\&upsi;}}_b\left|{\mathrm{\&omega;}}_b\right|L_3$

$T_4=e^{{\mathrm{\&upsi;}}_a\mathrm{\&beta;}}[T_3+T_h+{\mathrm{\&upsi;}}_b|{\mathrm{\&omega;}}_b|L_4-{\mathrm{\&omega;}}_{b}H-e^{{\mathrm{\&upsi;}}_a\mathrm{\&alpha;}}\left({\mathrm{\&upsi;}}_a{\mathrm{\&omega;}}_a{L}_4{e}^{{\mathrm{\&upsi;}}_a\mathrm{\&alpha;}}\right)]$

$T_h=P_h\frac{\mathrm{\&pi;}}{8}(D_h^2-D_m^2)$

$D_m=\sqrt{n}D$

${\mathrm{\&omega;}}_a=\frac{1.06\mathrm{n\&pi;}{D}^2{\mathrm{\&gamma;}}_a(\mathrm{DR}-1)}{{\mathrm{DR}}^2}$

${\mathrm{\&omega;}}_b=\frac{\mathrm{\&pi;}{D}^2{\mathrm{\&gamma;}}_b}{4}-\frac{1.06\mathrm{\&pi;}{D}^2{\mathrm{\&gamma;}}_a(\mathrm{DR}-1)}{{\mathrm{DR}}^2}$

Wherein, T ₁Locate to restrain total pull-back force (KN) for burying; T ₂It is the total pull-back force (KN) of first inclination section destination county tube bank; T ₃It is the total pull-back force (KN) of second inclination section starting point place tube bank; T ₄Be the total pull-back force (KN) of unearthed point place tube bank; L ₁Additional length (m) for tube bank; L ₂Be bury the some horizontal length (m) of deflecting terminal point of tube bank; L ₃Be tube bank horizontal section length (m); L ₄Be the horizontal length (m) of tube bank horizontal segment terminal point to unearthed point; H is the height (m) of tube bank apart from ground; υ _aFor the friction factor of tube bank, get 0.5 usually with ground; υ _bFor the friction factor of tube bank in the hole, get 0.3 usually, multitube returns when dragging between 0.3 ~ 0.5, and maximum is got υ _aω _aBe the total weight (KN/m) of unit length blank pipe bundle; ω _bBe unit length tube bank net buoyancy (KN/m) upwards; The penetrating angle (rad) of tube bank when α is back to drag; The unearthed angle (rad) of tube bank when β is back to drag; γ _aWeight for the per unit volume pipeline material; γ _bWeight (KN/m for mud in the per unit volume annular space and landwaste mixture ³); P _hFor the kinetic pressure of annular space mud, get 0.035 ~ 0.070MPa usually to pipeline; D is the external diameter (m) of single pipe; D _hBe bore diameter (m); D _mBe diameter (m) behind the tube bank area equivalent; DR is the ratio of single pipe external diameter and wall thickness; N is for comprising the number of pipeline in the tube bank.

4. according to the non-excavating construction method of the described electric power comb of claim 1, it is characterized in that described average every corresponding axial tension stress parameter of pipeline, adopt following representation to confirm:

${\mathrm{\&sigma;}}_x=\frac{T_x}{\mathrm{n\&pi;}{D}^2}\frac{{\mathrm{DR}}^2}{\mathrm{DR}-1}$

Wherein, σ _xBe axial tension stress (MPa) in the average every pipeline of pilot hole respective point; T _xBe the total pull-back force (KN) of pilot hole respective point tube bank.

5. according to the non-excavating construction method of the described electric power comb of claim 1, it is characterized in that described time hauling pipe road drawn the security parameter condition, must satisfy following condition:

σ _p<σ _allow

Wherein, σ _p=σ _x+ σ _a

${\mathrm{\&sigma;}}_a=\frac{E_{24}D}{2R_{\mathrm{avg}}}$

$R_{\mathrm{avg}}=\frac{2H}{{\mathrm{\&theta;}}^2}$

σ _pBending section interior conduit maximum tension stress (MPa) for the respective point place; σ _aBe respective point place bending section interior conduit maximum stress in bend (MPa); E ₂₄Be the Young's modulus (MPa) in the pipeline 24 hours; R _AvgBe the mean radius of curvature (m) of pipeline in the hole; θ is penetrating angle or unearthed angle (rad) of pipeline.

6. according to the non-excavating construction method of the described electric power comb of claim 5, it is characterized in that when the tension checking computations are carried out in described tube bank, the allowable tensile stress parameter of every pipeline in the tube bank, must less than its axial tension stress and flexural stress with, that is: σ _Allow<σ _x+ σ _a

Wherein, σ _AllowBe the allowable tensile stress of every pipeline, σ _xBe axial tension stress (MPa) in the average every pipeline of pilot hole respective point, σ _aBe respective point place bending section interior conduit maximum stress in bend (MPa).

7. according to the non-excavating construction method of the described electric power comb of claim 1, it is characterized in that when carrying out said compaction grouting that the suffered pressure outside parameter of pipeline adopts following representation to confirm:

P _net=p+γ _csH+P _ch-P _i

Wherein, P is grouting pressure (MPa); γ _CsWeight (KN/m for the per unit volume cement slurry ³); H is the thickness (m) of last overburden layer; P _ChFor the kinetic pressure (MPa) of cement slurry, be approximately equal to P to pipeline _hP _hFor annular space mud acts on the kinetic pressure (MPa) on the pipeline; P _iFor acting on the internal pressure (MPa) on the pipeline.

8. according to the non-excavating construction method of one of any described electric power comb of claim 1 to 7; It is characterized in that described method of construction and each parameter confirm representation; Be applicable to the administrative standard of design to electric power comb trenchless engineering, construction, tubing aspect, also be applicable to corresponding construction Supervision standard.

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