JP2005351429A - Design method for pipe-in-pipe construction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide design for smoothly applying pipe-in-pipe construction method. <P>SOLUTION: It is considered whether a new pipe can pass through based on pipe line investigation data of existing pipe and pipe length of new pipe which can pass through is determined when design of pipe-in-pipe construction method in which the new pipe is inserted into the existing pipe is performed. Bending angle of a joint of the new pipe when the new pipe is inserted in the existing pipe is determined based on pipe line investigation data. If the bending angle is in a tolerance range, insertion propulsion force of the new pipe is determined. If the determined insertion propulsion force is in a range of allowable resistant force of the new pipe, adoption of the new pipe is determined. If the bending angle exceeds the tolerance range, the type of the new pipe corresponding to that or length of the new pipe is determined, or laying length of the new pipe is reconsidered. If the insertion propulsion force exceeds allowable resistant force of the new pipe, the type of the new pipe corresponding to that is determined or laying length of the new pipe is reconsidered. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a design method for a pipe-in-pipe method.

The pipe-in-pipe method for inserting a new pipe into an existing pipe is positioned and developed as a method for renewing an old pipe (for example, Patent Document 1). In this case, there is no problem if the old pipe is laid in a straight line, but if this old pipe is bent at the joint between the pipes, the length of the new pipe to be laid is limited. At the same time, it is affected by the bending angle of the joint portion between the new pipes, and the insertion force of the new pipe becomes larger than that in the case of a straight line, which may cause various obstacles.
JP 11-193882 A

  Then, an object of this invention is to enable the design which can construct a pipe-in-pipe construction method smoothly.

  In order to achieve this object, the present invention determines whether or not a new pipe can be passed based on the pipe survey data of the existing pipe when designing a pipe-in-pipe method for inserting a new pipe into the existing pipe. The pipe length of the new pipe that can be passed is determined, and the bending angle of the new pipe joint when the new pipe is inserted into the existing pipe is determined based on the pipe survey data. If it is within the allowable range, the insertion thrust of the new pipe is obtained.If the calculated insertion thrust is within the allowable resistance of the new pipe, the adoption of the new pipe is determined, and the bending angle is If the allowable range is exceeded, determine the type of new pipe and / or the length of the new pipe, or review the laying length of the new pipe, and the insertion propulsive force will increase the allowable resistance of the new pipe. If so, decide the type of new pipe corresponding to it, Rui is characterized in carrying out the review of laying lengths of new pipe.

According to the present invention, in the above, when a new pipe is inserted into a pipe line of an existing pipe that is not uniform in bending angle in each joint and bends in the same direction, the pipe length of the new pipe is When the pipe length is equal to or larger than the existing pipe length,
Let L be the new pipe length,
Let n be the number of existing pipes,
The L ₁ ~L _n and tube length of the existing pipe,
_Let θ _{1 to} θ _{n be} the bending angles of existing pipe joints,
γ is a coefficient determined by the state in which the new pipe passes through the existing pipe,
The bending angle φ of the new pipe joint is

により求めることが好適である。

It is preferable to obtain by

According to the present invention, in the above, when a new pipe is inserted into a pipe line of an existing pipe that is not uniform in bending angle in each joint and bends in different directions, the pipe length of the new pipe is When the pipe length is equal to or larger than the existing pipe length,
Let D _{0 be} the inner diameter of the existing pipe,
Let L _{0 be} the length of the existing pipe,
θ is the bending angle in the existing pipe joint,
Let δ ₁ be the radial gap between the new pipe and the existing pipe,
m is a coefficient determined by the difference between the outer diameter of the new pipe and the inner diameter of the existing pipe,
The D ₅ as the outer diameter of the new pipe,
The bending angle φ of the new pipe joint is

により求めることが好適である。

It is preferable to obtain by

According to the invention, in the above,
μ is the coefficient of friction between the new pipe and the existing pipe,
Let W be the mass per new tube,
N is the number of new tubes inserted,
κ is an additional rate considering the bending of the joint,
New tube insertion force F
F = μ ・ W ・ N ・ κ
It is preferable to obtain by

According to the present invention, in the above, it is preferable that the premium rate κ is a variable that changes depending on the central angle of the bend of the pipe.
According to the present invention, in the above, the central angle of the bend of the pipe is Θ, and the rate of increase κ is κ = V · Θ + 1
However, V is preferably a variable that varies depending on the inner surface properties of the existing pipe.

  According to the present invention, it is determined whether a new pipe can pass based on the pipe survey data of the existing pipe, the length of the new pipe that can be passed is determined, and the existing pipe is determined based on the pipe survey data. The bending angle at the joint of the new pipe when the new pipe is inserted into this pipe is obtained. If it is within the allowable resistance range, determine whether to adopt the new pipe, and if the bending angle exceeds the allowable range, determine the type and / or length of the new pipe Alternatively, review the laying length of the new pipe, and if the insertion propulsion force exceeds the allowable resistance of the new pipe, determine the type of the new pipe corresponding to it or review the laying length of the new pipe. Design for smooth construction of pipe-in-pipe method It can be carried out to become.

  FIG. 1 shows a flow of a design method of a pipe-in-pipe method according to an embodiment of the present invention. Hereinafter, it demonstrates according to this flow.

[The length of the inserted new pipe]
For example, in the case of water pipes, not only at the time of renewing aging existing pipes, but in recent years, in order to cope with the congestion of underground buried objects, fume pipes are promoted in advance to form sheath pipes. There are many works to insert ductile pipes inside. Therefore, in the following, a case where a new pipe is inserted into these existing pipes or sheath pipes will be described.

  First, in step S101 of FIG. 1, the length of a new pipe that can pass through the existing pipe or the sheath pipe based on the investigation of the bending state of the pipe pipe is examined. At this time, it is necessary to perform different examinations depending on whether the new pipe is passed through the above-mentioned old or new sheath.

  That is, the pipe length of an existing pipe bent at the joint or a new pipe that can be inserted into the sheath pipe can be obtained based on the “Ductile Pipe Pipe-in-Pipe Method” JDPAT 36 Japan Ductile Iron Pipe Association Technical Data. At this time, in the case of an aging existing pipe, an in-pipe investigation is performed to obtain data such as the pipe inner diameter, pipe length, joint bending angle, and pipe inner surface conditions. On the other hand, in the case of a new sheath, the design is based on the data of the curvature of the bent portion and the pipe length. However, it is necessary to confirm that the sheath pipes are laid in the linear form as planned at the time of propulsion.

  Next, based on whether the bending state of the existing pipe or sheath pipe is a Z-shape, the length of the new tube that can be inserted is obtained using a different model formula. These are hereinafter referred to as “Model I” and “Model II”.

(Model I)
As shown in FIG. 2, the existing pipe or sheath pipe 1 is bent in a Z shape at two joint portions. The new pipe 2 is inserted into the existing pipe or the sheath pipe 1 in a state where a plurality of the new pipes 2 are joined to each other at the joint portion and are not bent at the joint portion. Moreover, the new pipe 2 shall comprise the joint part for mutually joining by the receiving structure which has the receiving port 3 in one end, and has the insertion port 4 in the other end. 5 is the tube part. Further, it is assumed that the bending angles at the two bent portions of the existing pipe or sheath pipe 1 bent in a Z-shape are equal. here,
L: New pipe 2 length (effective length)
D ₂ : The outer diameter of the tube part of the new pipe 2 D ₅ : The outer diameter of the receiving port 3 of the new pipe 2 P: The squeezing dimension of the receiving port of the new pipe 2 L ₀ : The length of the existing pipe or sheath pipe 1 Long)
D ₀ : Minimum inner diameter of existing tube or sheath tube 1 θ: Bending angle of existing tube or sheath tube 1 φ ₁ , φ ₂ : Angle formed by existing tube or sheath tube 1 and new tube 2 at the bent portion

によって、Ｚ字形に屈曲した既設管またはさや管１に挿入可能な新管２の管長Ｌを求めることができる。

Thus, the pipe length L of the existing pipe bent into a Z shape or the new pipe 2 that can be inserted into the sheath pipe 1 can be obtained.

(Model II)
As shown in FIG. 3, the existing pipe or sheath pipe 1 is bent in a dogleg shape at the joint portion. in this case,
φ ₀ : The angle formed by the existing pipe or sheath pipe 1 and the new pipe 2 at the bent portion,

によって、くの字形に屈曲した既設管またはさや管１に挿入可能な新管２の管長Ｌを求めることができる。

Thus, the pipe length L of the existing pipe bent into a dogleg shape or the new pipe 2 that can be inserted into the sheath pipe 1 can be obtained.

  From the calculation results of the above-described formulas (1) and (2), whether or not the existing pipe or the sheath pipe 1 can pass through the bent portion when the new pipe 2 is a regular pipe in step S102 of FIG. Determine. If it is possible to pass, the tube length is adopted, and if it is not possible to pass, in step S103, based on the calculation results by the above-described equations (1) and (2), the tube length that can be passed (becomes shorter than the regular tube). ) Is calculated.

[Calculation of bending angle φ of new pipe based on survey data]
Next, in step S104 of FIG. 1, the maximum joint bending angle φ of the inserted new pipe 2 is calculated based on the pipe survey data of the existing pipe or sheath pipe 1 described above.

(A) When inserting into an existing pipe or sheath tube that bends in the same direction (A-1) When the new tube 2 is longer than the existing tube or sheath tube 1 (L ≧ L ₀ ) (A-1-1) )
The case where the bending angle is not uniform in each of the plurality of joint portions in the existing pipe or sheath pipe 1 will be described. FIG. 4 shows the relationship between the existing pipe or sheath pipe 1 and the new pipe 2 in this case. Here, the bending angle φ of the joint portion of the new pipe 2 to be inserted largely depends on the inner diameter D ₀ of the existing pipe or sheath pipe 1, its pipe length L ₀ , and its bending angle θ. Assuming that the sheath pipes 1 are laid in the number of n or less, the following formula (3) is used.

ここで、
Ｌ_１〜Ｌ_ｎ：既設管またはさや管１の長さ
θ_１〜θ_ｎ：既設管またはさや管１の屈曲角
γ：新管が既設の管の内部を通過する状態によって決定される係数
とし、新管２の外径は前述のＤ_５であるとする。

here,
L _{1 to} L _n : Length of existing pipe or sheath pipe 1 θ ₁ to θ _n : Bending angle of existing pipe or sheath pipe 1 γ: A coefficient determined by a state in which the new pipe passes through the existing pipe , the outer diameter of the new pipe 2 is assumed to be D ₅ above.

The expression L ′ will be described. L ′ indicates the penetration length when the new pipe 2 starts to bend in the existing pipe or sheath pipe 1 into which it has newly entered. As shown in FIG. 5, when the new pipe 2 having a smaller diameter than the existing pipe or sheath pipe 1 is inserted into a straight portion of the existing pipe or sheath pipe 1, the existing pipe or sheath pipe 1 is It will be in the state supported by the bottom part. At this time, the center C ₂ of the new pipe 2 exists at a position lower than the center C ₁ of the existing pipe or the sheath pipe 1. When the existing tube or sheath tube 1 is bent, the new tube 2 is theoretically when it hits the side of the existing tube or sheath tube 1 as shown by the phantom line in FIG. The bending is started by being guided by the existing pipe or sheath pipe 1. However, in order to thus Shinkan 2 receives the guide against the existing pipe or side of the sheath tube 1, until Shinkan 2 As shown the height of the center C ₁ of the center C ₂ of sheath tube 1 It is necessary to lift up. However, in reality, it is reasonable to think that the new tube 2 starts to bend before it rises to such a height. Therefore, here, as shown in FIG. 5, from the side of the new pipe 2 to the side of the existing pipe or sheath 1 when the new pipe 2 is supported on the bottom of the existing pipe or sheath 1 The new tube 2 is d = (D ₀ −D ₅ ) / γ sin θ ₁
It is assumed that the new pipe 2 starts to bend when it is shifted to the side and has a height corresponding thereto, and the above-described equation L ′ is derived based on this concept. Note that the value of the coefficient γ is determined empirically depending on the state in which the new pipe 2 passes through the existing pipe or the sheath pipe 1, and specifically takes a value in the range of 2 to 10. There are many cases.

(A-1-2)
Next, as shown in FIG. 6, a case where the bending angle is uniform in each of the plurality of joint portions in the existing pipe or sheath pipe 1 will be described. In this case, the bending angle φ of the new tube 2 can be obtained using the following equation (4).

(A-2) When the new pipe 2 is shorter than the existing pipe or sheath pipe 1 (L <L ₀ ) In this case,
φ = θ
It becomes.

(B) When inserting into an existing pipe or sheath pipe that bends in a different direction (B-1) When the new pipe 2 is longer than the existing pipe or sheath pipe 1 (L ≧ L ₀ ) Existing pipe by pipe test Or it turned out that the angle of the joint of the new pipe 2 to be inserted becomes smaller when the sheath 1 is bent in a different direction than when the sheath 1 is bent in the same direction. Therefore, the bending angle φ of the new pipe 2 in this case is calculated by the following formula (5) in consideration of the inner diameter D ₀ , the pipe length L ₀ , and the bending angle θ of the existing pipe or sheath pipe 1 based on FIG. .

ここで、
δ_１：新管２と既設管またはさや管１との径方向の隙間（＝Ｄ_０−Ｄ_５）
ｍ：新管の外径と既設の管の内径との差によって決定される係数（新管の外径と既設の管の内径との差にもとづいて経験的に求められるものであって、具体的には２〜２０の範囲内の値をとることが多い）
である。このとき、δ_２＝Ｌ_０ｓｉｎθ＋δ_１／ｍとして、δ_２＞δ_１のときに新管２は屈曲可能であるが、そうでない場合は屈曲しない。また、図７に示すように、αは新管２が屈曲したときの角度、βは新管２が屈曲していないときの角度である。

here,
δ ₁ : Clearance in the radial direction between the new pipe 2 and the existing pipe or sheath pipe 1 (= D ₀ -D ₅ )
m: a coefficient determined by the difference between the outer diameter of the new pipe and the inner diameter of the existing pipe (which is obtained empirically based on the difference between the outer diameter of the new pipe and the inner diameter of the existing pipe, In many cases, it takes a value in the range of 2 to 20)
It is. At this time, assuming that δ ₂ = L ₀ sin θ + δ ₁ / m, the new tube 2 can be bent when δ ₂ > δ ₁ , but does not bend otherwise. Further, as shown in FIG. 7, α is an angle when the new tube 2 is bent, and β is an angle when the new tube 2 is not bent.

(B-2) When the new pipe 2 is shorter than the existing pipe or sheath pipe 1 (L <L ₀ ) In this case,
φ = θ
It becomes.

[Application of calculation formula for bending angle φ of new pipe]
Next, based on the result of the investigation of the existing pipe or sheath pipe described above, whether the existing pipe or sheath pipe is bent in the same direction as in (A) above or different from that in (B) above. A method for determining whether or not the vehicle is bent in the direction will be described. Table 1 shows an example of the investigation result of the existing pipe or sheath pipe and the determination result of the bending direction. Here, the bending angle in the vertical direction is + for upward and-for downward, and in the left-right direction is + for right and-for left.

In Table 1, “single distance” indicates the length of each existing pipe constituting the existing pipe, and “cumulative distance” indicates the distance from the starting point of the pipe to each pipe, that is, the single distance to each pipe. Indicates the sum of That is, Table 1 shows the survey results for 11 existing pipes. The “inner diameter of the existing pipe” is measured in the horizontal direction and the vertical direction, and the smaller one is set as the minimum inner diameter D ₀ . The body size, that is, the size of the gap between the distal end of the insertion port and the rear end of the reception port in the joint of the reception structure is measured at four positions on the right, lower, and left along the horizontal end surface of the pipe. ing.

  The bending angle of the joint can be obtained by calculation in the vertical direction and the horizontal direction from the measurement result of the body size. Table 1 shows the results. Further, the sum of the absolute values of the bending angles in the vertical direction and the horizontal direction of the joints adjacent to each other is obtained. Table 1 also shows the results.

  First, the sum of the absolute values of the bending angles in the vertical direction and the sum of the absolute values of the bending angles in the left and right directions of two joints adjacent to each other is compared. Is generally in the up-down direction or left-right direction. Next, look at the bending direction of two consecutive joints in either the up-down direction or the left-right direction determined as described above. If “+”, “+”, or “−” “−” If it is “+”, “−” or “−”, “+”, it is determined that it is “bent in different directions”.

  Based on the above, either the calculation formula of “when inserting into an existing pipe or sheath tube that bends in the same direction” or the calculation formula of “when inserting into an existing pipe or sheath tube that bends in a different direction” described above. Can be determined.

As the value of the bending angle θ of the existing pipe or sheath pipe, the value of the combined angle obtained by vector synthesis of the value of the bending angle in the vertical direction and the value of the bending angle in the horizontal direction shown in Table 1 is applied.
Among the values for the new pipe, the outer diameter (D ₅ ) applies the reference value of the outer diameter of the receiving port. Further, the length (L) of the new pipe is applied as (effective length reference value) + (receiving port swallowing dimension reference value).

[Examination of allowable bending angle]
Next, when the new pipe 2 is inserted into the existing pipe or sheath pipe 1 bent in this way, the pipe for pipe-in-pipe method used as the new pipe 2 can be piped within the allowable bending angle range. Whether or not it is possible will be examined based on the calculation results using the above-described equations.

Table 2 shows examples of allowable bending angles of pipes for pipe-in-pipe method. Here, the allowable bending angle theta _a design-time and the original allowable bending angle theta _b is shown. Allowable bending angle theta _a design time, in anticipation of safety, it is set to 1/2 of the original allowable bending angle theta _b.

That is, it is determined in step S105 in FIG. 1, the value of the bending angle φ of the new tube 2 obtained by using the equations described above, whether it is less than the allowable bending angle theta _a design time. If was allowable bending angle theta _a more design-time, in step S106 of FIG. 1, determines whether less than the original allowable bending angle theta _b. If the original allowable bending angle θ _{b is} greater than or equal to the original allowable bending angle θ _b , the pipe length of the new pipe satisfying φ <θ _b is calculated in step S107 of FIG. 1, and the new pipe 2 having a length L shorter than the initial setting is laid. To consider.

[Calculation of insertion force considering the bending angle φ of the new tube]
Consider the pipeline shown in plan view in FIG. Here 7 starting pit, the arrival pit 8, L _C is the length of the curved portion of the conduit, BC is the starting point of the curve section, EC is the curved portion ending, L ₁ is the attainment pit from the end EC curved portion 8 the distance to, L ₂ is the distance from the starting pit 7 to the start point BC of the curve section. In such pipes that can be used for curve propulsion with the pipe-in-pipe method, the propulsive force for that is expressed in the following formula (6) according to “Guidelines and Explanation of Sewerage Promotion Method-2000 Version”, etc. Can be calculated.

ここで、
Ｆ：総推力
Ｆ_０：先端抵抗力
ｆ：直線推進の場合の単位長さあたりの抵抗力
ｊ：曲線部における推進管の本数
である。Ｋは、曲線部を超えた直線部について乗じる係数で、

here,
F: total thrust F ₀ : tip resistance force f: resistance force per unit length in the case of linear propulsion j: the number of propulsion pipes in the curved portion. K is a coefficient by which the linear part exceeding the curved part is multiplied,

ここで、
ｋ：曲線部における推進方向に対する法線方向の摩擦抵抗にかかわる係数
である。λは、曲線部と直線部との推進抵抗の比で、

here,
k: a coefficient related to the frictional resistance in the normal direction to the propulsion direction in the curved portion. λ is the ratio of the driving resistance between the curved part and the straight part,

である。

It is.

In the case of the pipe-in-pipe method, the tip resistance force F ₀ is 0, so equation (6) is

となる。式（９）の右辺の第１項は曲線部の終点ＥＣから到達立坑８までの区間についての推力、第２項は曲線部についての推力、第３項は発進立坑７から曲線部の始点ＢＣまでの区間についての推力である。

It becomes. The first term on the right side of Equation (9) is the thrust for the section from the end point EC of the curved portion to the reaching shaft 8, the second term is the thrust for the curved portion, the third term is the starting point BC from the starting shaft 7 to the curved portion. This is the thrust for the interval up to.

Here, as a typical value, when L = 4 m and k = 0.4, the result of calculating the value of K ^j −λ is shown for the range where the central angle of the curved portion is less than 90 degrees. 9 shows. From FIG. 9, it can be seen that when the propulsion extension is 20 to 400 m (50 to 100 tubes having an effective length L = 4 m), K ^j −λ> 0, that is, K ^j > λ.

  Therefore, although the thrust is calculated to be somewhat large, the equation (9) can be simplified as the following equation (10).

さらに、既設の管路の内面にライニングが施され、この既設の管路の曲線部の曲率半径が１００〜５００ｍで、推進延長が２０〜４００ｍ（有効長Ｌ＝４ｍの管が５０〜１００本）の場合の、曲線部の中心角とＫ^ｊとの関係について求めた結果を図１０に示す。図１０より、Ｋ^ｊの値は、曲線部の曲率半径に関係なく、中心角によって同程度の値となることがわかる。また、実用的と考えられる中心角が７０度以下の範囲では、曲線部の中心角をΘ度として、
Ｋ^ｊ＝０．０１Θ＋１
と考えて問題ないことがわかる。

Furthermore, the inner surface of the existing pipe line is lined, the radius of curvature of the curved part of the existing pipe line is 100 to 500 m, the propulsion extension is 20 to 400 m (50 to 100 pipes having an effective length L = 4 m) FIG. 10 shows the result obtained for the relationship between the central angle of the curved portion and K ^{j in} the case of). From FIG. 10, it can be seen that the value of K ^j is approximately the same depending on the central angle regardless of the radius of curvature of the curved portion. Moreover, in the range where the central angle considered to be practical is 70 degrees or less, the central angle of the curved portion is defined as Θ degrees,
K ^j = 0.01Θ + 1
It turns out that there is no problem.

  Therefore, the thrust can be obtained using the following equation (11).

この式（１１）は、図８に示すように曲線部と直線部とにより構成されかつ内面ライニングが施された新設のさや管内にダクタイル管を挿入する場合に使用することができるが、さや管が既設管である場合のように継手の屈曲角が一様でない管路を含む場合は、下記の式（１２）を用いて計算することができる。

This equation (11) can be used when a ductile tube is inserted into a newly formed sheath tube having a curved portion and a straight portion as shown in FIG. Can be calculated using the following equation (12) when the pipe includes a pipe with a non-uniform bend angle, as in the case of an existing pipe.

ここで、
Ｌ_Ｔ：管路の全長
である。

here,
L _T is the total length of the pipeline.

  The expression (12) can be rewritten as the following expression (13) in consideration of the safety factor.

ここで、
μ：摩擦係数
Ｗ：新管の１本あたりの質量（基準値）
Ｎ：挿入本数
κ：継手の曲がりを考慮した割増率
である。なお、摩擦係数μの値は、既設管またはさや管の種類や内面状況によって適宜決定されるものであり、たとえばライニング無しの場合はμ＝０．２〜０．５、ライニング有りまたはコンクリート管の場合はμ＝０．４〜０．９などとなる。

here,
μ: Friction coefficient W: Mass per new pipe (reference value)
N: Number of insertions κ: Additional rate considering bending of the joint. Note that the value of the coefficient of friction μ is appropriately determined depending on the type of existing pipe or sheath pipe and the inner surface condition. For example, when there is no lining, μ = 0.2 to 0.5, with lining or with concrete pipe In this case, μ = 0.4 to 0.9 or the like.

The premium rate κ will be described. This rate of increase κ corresponds to (0.01Θ + 1) in equation (12), that is, K ^j , and as described above, the thrust and the straight line when the propelling pipe is propelled by the curved portion of the sheath pipe are expressed as follows. The ratio with the thrust in the case of propulsion hardly changes even if the diameter and the curvature radius of the propulsion pipe are different, and becomes almost constant depending on the central angle of the curved portion. For this reason, as shown in equations (12) and (13), it is appropriate to calculate the total thrust by multiplying the thrust calculated on the assumption of a straight line by an additional rate κ based on the central angle of the curved portion. is there.

  (0.01Θ + 1) in the equation (12) indicates the additional rate κ for the existing pipe lined on the inner surface as described above. The value of κ is the value of the existing pipe line. It is appropriate to change as follows according to the state of the inner surface of the plate.

κ = 0.005Θ + 1 No lining κ = 0.01Θ + 1 Lining or concrete pipe Next, the center angle Θ of the curved portion will be described. As shown in FIG. 11 (a), if the bending angle at each joint portion of the existing pipe or sheath pipe 1 that is uniformly curved is θ _i , the central angle Θ is the sum of the bending angles θ _i , that is,
Θ = Σθ _i
It becomes. Further, when the curve is not uniform as shown in FIG. 11B, Θ is similarly expressed by the sum of the bending angles θ _i in the joint portions of the existing pipes or the sheath pipes 1, that is, the above equation. . Therefore, the central angle Θ can be easily calculated by using the bending angle θ _i obtained as shown in Table 1.

  Based on the above, in step S108 of FIG.

[Examination of allowable resistance]
As an example of the joint portion of the new pipe 2 to be propelled, as shown in FIG. 12, an annular lock ring 12 divided in the circumferential direction accommodated in the accommodation groove 11 on the inner circumference of the receptacle 3 is connected to the receptacle 3. The inner peripheral side of the lock ring 12 is fitted in the annular groove 14 on the outer periphery of the insertion port 4 by reducing the diameter by a plurality of set bolts 13 in the circumferential direction screwed into the wall portion of the receiving port 3 from the outer surface. There is a standard system that can be embedded. In such a case, the propulsive force can be transmitted between the insertion port 4 and the receiving port 3 by the lock ring 12.

  As another example of the joint portion of the new pipe to be propelled, as shown in FIG. 13, a flange 16 reinforced with a rib 15 is provided on the outer surface of the insertion port 4, and this flange 16 is brought into contact with the end surface of the receiving port 3. There is a flange-rib type that transmits the propulsive force between the insertion port 4 and the receiving port 3, and this flange-rib type joint is higher than the standard type joint described above. Has allowable resistance.

In step S109 in FIG. 1, the allowable resistance force F _A of the coupling of the standard scheme of Figure 12, to determine whether it exceeds the thrust F obtained as described above. If so, in step S110, it is determined to use a standard pipe having the standard joint.

If the allowable resistance force F _A of the coupling of the standard scheme of Figure 12 is less than thrust F, at step S111, it adopts the flange ribbed tubes of a large 13 allowable resistance than that. Table 3, the allowable resistance F ₁ of the joint of the tube of the flange rib method, and the tube type or tube wall thickness, a representation based on the nominal diameter of the tube. The unit of the numerical value is [kN]. Therefore, in step S112, the allowable resistance force F ₁ of the flange ribbed tube it is determined whether it exceeds the thrust F obtained as described above. When exceeding, in step S113, adoption of the pipe with a flange and a rib is determined. If the allowed resistance force F ₁ of the flange ribbed tube is less thrust F, it can be determined that the conduit length of the propulsion tube to be a cause of thrust F is too long. Therefore, in step S114, a countermeasure such as reviewing the construction extension is taken.

It is a flowchart which shows the design method of the pipe in pipe construction method of embodiment of this invention. It is a figure which shows a structure in case an existing pipe or a sheath pipe is bent in Z shape in two joint parts. It is a figure which shows a structure in case the existing pipe or a sheath pipe is bent in the shape of a dogleg in a joint part. It is a figure which shows the case where the bending angle in the some joint part in the existing pipe | tube or sheath pipe | tube bent in the same direction is not uniform. It is a cross-sectional view which shows a mode that a new pipe is inserted in an existing pipe or a sheath pipe. It is a figure which shows the case where the bending angle in the some joint part in the existing pipe | tube or sheath pipe | tube bent in the same direction is uniform. It is a figure which shows the case where a new pipe | tube is inserted in the existing pipe | tube or sheath pipe | tube bent in a different direction. It is a figure which shows the example of the pipe line of the existing pipe | tube or sheath pipe | tube comprised by a curved part and a linear part. Is a graph showing the calculation result of the K ^j 1-? For the conduit of Figure 8. It is a figure which shows the result calculated ^| required about the relationship between the central angle of the curve part about the pipe line of FIG. 8, and ^Kj . It is a figure for demonstrating center angle (theta) of a curve part. It is sectional drawing of a propulsion pipe joint of a standard system. It is sectional drawing of a propulsion pipe joint of a flange rib system.

Claims (6)

When designing a pipe-in-pipe method for inserting a new pipe into an existing pipe,
Based on the pipe survey data of the existing pipe, whether or not the new pipe can pass is determined, the pipe length of the new pipe that can pass is determined,
Based on the pipe survey data, find the bending angle in the joint of the new pipe when the new pipe is inserted into the existing pipe,
If this bend angle is within the allowable range, find the new tube insertion force,
If the required insertion propulsion force is within the allowable resistance of the new pipe, decide to adopt the new pipe,
If the bending angle exceeds the allowable range, determine the type of new pipe and / or the length of the new pipe, or review the laying length of the new pipe,
If the insertion propulsion force exceeds the allowable resistance of the new pipe, determine the type of the new pipe corresponding to it, or review the laying length of the new pipe.
Design method of pipe-in-pipe method characterized by this. When a new pipe is inserted into a pipe line of an existing pipe where the bending angle at each joint is not uniform and bends in the same direction, the pipe length of the new pipe is equal to or equal to the pipe length of the existing pipe When it is larger than the tube length,
Let L be the new pipe length,
Let n be the number of existing pipes,
The L ₁ ~L _n and tube length of the existing pipe,
_Let θ _{1 to} θ _{n be} the bending angles of existing pipe joints,
γ is a coefficient determined by the state in which the new pipe passes through the existing pipe,
The bending angle φ of the new pipe joint is

The pipe-in-pipe method design method according to claim 1, wherein the pipe-in-pipe method is calculated by: When a new pipe is inserted into a pipe line of an existing pipe where the bending angle at each joint is not uniform and bends in a different direction, the pipe length of the new pipe is equal to or equal to the pipe length of the existing pipe When it is larger than the tube length,
Let D _{0 be} the inner diameter of the existing pipe,
Let L _{0 be} the length of the existing pipe,
θ is the bending angle in the existing pipe joint,
Let δ ₁ be the radial gap between the new pipe and the existing pipe,
m is a coefficient determined by the difference between the outer diameter of the new pipe and the inner diameter of the existing pipe,
The D ₅ as the outer diameter of the new pipe,
The bending angle φ of the new pipe joint is

The pipe-in-pipe method design method according to claim 1, wherein the pipe-in-pipe method is calculated by: μ is the coefficient of friction between the new pipe and the existing pipe,
Let W be the mass per new tube,
N is the number of new tubes inserted,
κ is an additional rate considering the bending of the joint,
New tube insertion force F
F = μ ・ W ・ N ・ κ
The pipe-in-pipe method for designing a pipe-in-pipe method according to any one of claims 1 to 3, wherein the design method is obtained by:   5. The pipe-in-pipe design method according to claim 4, wherein the rate of increase κ is a variable that changes depending on the center angle of the bend of the pipe. With the center angle of the bend of the pipe as Θ,
κ = V ・ Θ + 1
6. The pipe-in-pipe design method according to claim 5, wherein V is a variable that varies depending on the inner surface properties of an existing pipe.

Images