JPS5930861B2 - Buried piping construction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a buried piping construction method that prevents uneven settling of pipe bodies when pulling out protective sheet piles during construction of buried piping.

Generally, when constructing underground piping, as shown in the cross-sectional view in Figure 1, protective sheet piles 1, 1 are placed underground along the pipeline to a certain width and depth. Then, the earth and sand between the sheet piles 1 and 1 is removed to a predetermined depth to create a buried trench 2, and the pipe body 3 is laid on the bottom 2a of the buried trench 2 to form a conduit. The method used is to backfill with earth and sand, and then pull out and remove the 1.1 sheet pile.

In the above construction method, the sheet piles 1, 1 are driven in to protect the surrounding earth and sand from collapsing when forming the buried trench 2, but regulations require that they be pulled out and removed after the buried piping is constructed. It is mandatory.

However, when the sheet piles 1, 1 are pulled out, a void is created in the ground after being pulled out by the cross-sectional area of the sheet pile and the soil removed by the pulling out, and as a result, the soil moves to fill such a void. The ground sinks.

The amount of ground subsidence mentioned above is calculated as follows.

That is, in the plan explanatory view of FIG. 2A and the side explanatory view of the opening in the figure, the cross-sectional area S of the sheet pile 1 is 5=(HXt), where the width of the sheet pile is H1 and the thickness is t.

In addition, the gap created after pulling out one set of left and right sheet piles is as follows: Gap per set of sheet piles = SxLx2x (1+α) However, S
: Cross-sectional area of 1 sheet pile L: Length of sheet pile in the ground α: Adhesion rate of soil to 1 sheet pile.

Therefore, the amount of subsidence δ is expressed as.

For example, applying the above formula to a 5p-n type sheet pile, L: 600cm, U: 300, 771.
Since H: 40cm, t: 10crrL, and 1°A = 150 boxes, the amount of ground subsidence will be 16CrrL.

Such ground subsidence inevitably causes buried pipes to subside.

Subsidence of buried pipes does not pose any particular problem if the pipe body and the ground settle uniformly, but as shown in the explanatory diagram in Figure 3,
In the part where one end of the pipe body 3 is fixed by the pit 4 etc., the pipe body 3 buried in the ground as shown by the dotted line causes uneven settlement as shown by the solid line, and as a result, this part Excessive stress is generated in the tube body 3a, causing damage.

From the above-mentioned viewpoint, the present invention provides a buried piping construction method that does not cause uneven settling of the pipe body due to ground subsidence after pulling out the sheet pile. The feature is that the pipe body is buried by predicting the amount in advance and backfilling the trench with earth and sand while lifting the pipe body by an amount corresponding to the amount of ground subsidence. It is.

Next, the present invention will be explained with reference to examples and drawings.

4 to 9 show the method of the invention in the order of steps.

In each figure, A is a front view of the buried pipe body, and the opening is A- in figure A.
, is a sectional view taken along line A.

First, as shown in FIG. 4, after sheet piles 1, 1 are driven into the ground, earth and sand between the sheet piles 1, 1 is removed to create a burial trench 2.

3a is a pipe fixed to the pit 4, and 3e is an existing pipe on the other side.

Next, as shown in FIG. 5, a tube 3b is placed between the existing tubes 3a and 3c.

3c and 3d are laid, and the respective pipe bodies are connected by welding.

The length l of the pipe bodies 3b to 3d is, for example, 18 m, the depth h from the ground surface to the top surface of the pipe body is, for example, 1.5 m, and the diameter R of the pipe body is, for example, 600 groups.Thereafter, as shown in FIG. Connected pipe bodies 3b, 3
Suspend the hanging tools 6, 6 suspended from the tow truck 5.5 on the ground between c and 3d, predict the amount of ground subsidence that will occur after pulling out the sheet pile using the above formula, and calculate the amount commensurate with the predicted amount of subsidence. , that is, the amount of subsidence equal to or greater than the predicted subsidence.
It is hoisted upward by the tow truck 5, 5 by an amount of about 0.0 mm.

In this state, as shown in FIG. 7, the tube body ib. 3c, 3d
The space created on the lower surface is backfilled with earth and sand 7, and the backfilled earth and sand 7 is further compacted.

Note that the backfilling earth and sand 7 is applied to the lower half portion 12 in the circumferential direction of the pipe body.
A range r of about 0° is appropriate.

Next, the hanging tools 6, 6 are removed, and the entire buried trench 2 is backfilled with earth and sand, as shown in FIG. 8, and after that, the sheet piles 1, 1 are pulled out.

FIG. 9 shows the state after the sheet pile is pulled out. Due to the ground subsidence after the sheet pile is pulled out, the ground sinks from the state shown by the dotted line before the sheet pile is pulled out to the state shown by the solid line.

At this time, the buried pipes 3b, 3c, and 3d shown by dotted lines, which have been raised in advance by an amount corresponding to the amount of ground subsidence, sink with the ground subsidence and return to the normal state at the time of installation shown by solid lines.

Therefore, the pipe body will not settle unevenly due to ground subsidence.

As can be seen from the above description, according to the present invention, even if ground subsidence occurs due to the removal of protective sheet piles during construction of buried pipes, the buried pipe bodies will settle unevenly, causing excessive damage to the pipe bodies. This method does not generate any significant stress, allowing pipe bodies to be buried safely and accurately, and is effective not only against ground subsidence caused by pulling out sheet piles, but also against ground subsidence caused by other causes. Excellent effects are brought about.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the construction of the buried pipe, Figure 2 is an explanatory diagram of the amount of ground subsidence, Figure 3 is an explanatory diagram showing the state of uneven settlement of the buried pipe, and Figures 4 to 9 show the method of this invention. It is an explanatory diagram showing the order of steps. In the drawing, 1... Sheet pile, 2... Buried trench, 3...
・Pipe body, 4... Pit, 5... Tow truck, 6...
- Hanging equipment, 7...earth and sand.

Claims (1)

[Claims] 1 Buried piping consisting of laying a pipe body in a buried trench formed by sheet piles driven along a pipeline to be buried, then backfilling the buried trench with earth and sand, and then pulling out the sheet piles. In the construction method, the amount of ground subsidence caused by pulling out the sheet pile is predicted in advance, and the pipes laid in the buried trench are lifted by an amount corresponding to the amount of ground subsidence, and earth and sand is buried in the buried trench. A buried pipe construction method characterized by returning the pipe body and burying the pipe body.