JP4196289B2 - Pile construction method - Google Patents

Description

  The present invention relates to a method for constructing a pile body for driving a pile body such as a steel sheet pile from above an obstacle such as a pipe to the lower ground.

  Some oil tanks designed and constructed according to past standards do not meet the current seismic performance standards, especially because the strength of the supporting ground against liquefaction is not sufficient, which can cause damage due to ground liquefaction during large earthquakes. Because there are things that can be assumed, countermeasures are urgently needed.

  Various methods have been proposed as liquefaction prevention measures for the supporting ground of existing oil tanks. As a method that can be implemented relatively easily and inexpensively, as shown in FIG. The construction method of providing the middle wall body 2 is considered promising. According to such a construction method, the liquefied layer 3 immediately below the tank 1 is isolated from the surroundings by the underground wall body 2, and the deformation of the liquefied layer 3 is restrained by the ring effect of the underground wall body 2 to be liquid. It is said that the strength against liquefaction can be increased, thereby effectively preventing liquefaction.

By the way, such a closed annular underground wall body 2 is generally provided by driving steel sheet piles while connecting them in the circumferential direction via joints. In this case, the closed annular underground wall body 2 is laid on the ground surface and connected to the tank 1. Since the steel sheet pile cannot be driven directly into the lower ground of the existing pipe 4 by a normal construction method, conventionally, the service of the tank 1 is temporarily stopped and the pipe 4 is dismantled and removed. He was trying to recover after driving a sheet pile. However, since such a method is inefficient, recently, for example, as shown in Patent Document 1, a construction method for driving a steel sheet pile without dismantling and removing the pipe 4 has been proposed. This is because two steel sheet piles driven on both sides of the pipe 4 are connected to each other by a bonded steel plate below the pipe 4, and the two connected steel sheet piles are pressed into the ground simultaneously by two driving machines. That's it.
Japanese Patent No. 325283

  However, in the construction method shown in Patent Document 1, not only the operation of connecting the bonded steel sheet to the steel sheet pile but also two driving machines are required, and two steel sheet piles connected by the bonded steel sheet are used. Since press-fitting at the same time is not always easy, development of an effective method capable of performing such work more efficiently has been desired.

  In view of the above circumstances, the pile body construction method of the present invention is basically driven by a pile driving machine such as a vibro hammer while adding a short unit pile body below the obstacle, When driving the unit pile body, a frame body that can move up and down outside the obstacle is interposed between the pile driver and the unit pile body, and the unit pile body is driven through the frame body. Is.

  That is, in the construction method of the pile body of the present invention, the pile driving machine can be connected to the upper part, the lower part has an opening of a size through which an obstacle can pass, and can be attached to the outside of the obstacle. Using a highly rigid frame body whose internal effective height dimension is set to be greater than the driving stroke of the unit pile body, the frame body is connected to the pile driving machine and attached to the outside of the obstacle so that it can move up and down. Attach a gripping tool to the opening of the unit and hold the unit pile body on the gripping tool, and from the state where the obstacle is located in the lower part inside the frame body, The unit after driving into the ground below the obstacle, and when the unit pile body is driven to the position where the obstacle reaches the inside upper part of the frame body, the driving is interrupted, and the unit after the frame body is pulled up and a new unit pile body is driven in Add to pile Is obtained by further typing is going as it brought gripped both gripper.

  According to the present invention, a frame body that can move up and down with respect to an obstacle is interposed between the pile driving machine and the pile body, and the unit pile body is driven through the frame body while being added below the obstacle. Thus, various pile bodies can be driven efficiently from the upper side of the obstacle to the lower ground in the same manner as a normal pile driving operation by a conventional pile driving machine.

  An embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 8, the present embodiment is applied to a case where a closed annular underground wall 2 made of a steel sheet pile is provided around the tank 1 as a liquefaction prevention measure for the supporting ground of an existing oil tank. In this case, the steel sheet pile is driven into the lower ground from above the existing pipe 4 that becomes an obstacle for the steel sheet pile driving operation.

  In the present embodiment, the basic unit is that a short unit steel sheet pile 5 obtained by cutting a normal steel sheet pile into a predetermined length is sequentially driven by a pile driving machine 6 such as a vibro hammer while being added below the pipe 4. When the unit steel sheet pile 5 is driven in, the frame body 7 is interposed between the pile driving machine 6 and the unit steel sheet pile 5 and the unit steel sheet pile 5 is driven through the frame body 7. It is what.

  As shown in FIG. 2, the frame body 7 used in the present embodiment is a highly rigid thing in the form of a downward-facing rectangular three-way frame with the lower part opened, and the upper part is against the pile driving machine 6 such as a vibro hammer. And an opening 8 through which the pipe 4 can pass is formed in the lower part, and the internal effective height dimension h is the unit steel sheet pile. 5 or more (more strictly speaking, the driving stroke + the outer diameter of the pipe 4 + the margin). A holding tool 9 that holds the upper part of the unit steel sheet pile 5 can be attached to the opening 8 at the lower part of the frame body 7.

  The construction procedure of the construction method of the present embodiment will be specifically described. First, as shown in FIG. 1, a work pit 10 for setting the unit steel sheet pile 5 directly under the pipe 4 is excavated. At that time, if necessary, the groundwater level may be lowered by, for example, a well point method. Then, the temporary beam 11 is installed so as to straddle the work pit 10, the upper part of the unit steel sheet pile 5 to be driven first is held by the holding tool 9, and the holding tool 9 is supported on the temporary beam 11 by a crane or the like. Slide it to just below the pipe 4 at least.

  As shown in FIG. 2, the frame body 7 connected to the pile driving machine 6 is lowered from a position directly above the gripping tool 9 arranged immediately below the pipe 4, and passes through the pipe 4 into the opening 8 at the lower part thereof. The gripping tool 9 is attached to the opening 8. As a result, as shown in FIG. 3, the frame body 7 is mounted on the outside of the pipe 4 so as to be movable up and down, and the unit steel sheet pile 5 naturally faces the driving position, so that the temporary beam 11 is retracted at that time. .

  As shown in FIG. 3, driving is started from a state where the pipe 4 is located at the lower inner side of the frame body 7 (upper limit position), and the pipe 4 is placed on the inner upper side of the frame body 7 as shown in FIG. 4. Once the driving position is reached (lower limit position), further driving is impossible because the pipe 4 and the frame body 7 interfere with each other, and the driving is interrupted at that time.

  Therefore, the gripping of the unit steel sheet pile 5 by the gripping tool 9 is released, the frame body 7 is lifted together with the gripping tool 9 and returned to the upper limit position, and a new unit steel sheet pile 5 is driven as shown in FIG. After the steel sheet pile 5 is added and the gripping tool 9 is gripped, the driving is resumed.

  After the above procedure is repeated and a predetermined number of unit pile steel sheet piles 5 are added to reach a predetermined depth, normal steel sheet piles 12 are attached to both sides of the steel sheet pile as shown in FIG. The work is completed by driving in while being connected by a joint, constructing a closed annular underground wall 2 as shown in FIG. 8 and finally filling back the work pit 10.

  According to the above construction method, the unit steel sheet pile 5 is added in a state where the frame body 7 is pulled up to the upper limit position, and the driving operation is repeated until the frame body 7 reaches the lower limit position. The sheet pile can be driven without hindrance. In addition, the pile driving machine 6 itself can be used as it is by simply using the highly rigid frame body 7, and there is no need for complicated mechanisms and troublesome operations other than the frame body 7, The operation can be performed very efficiently.

  As an application example of the above embodiment, as shown in FIG. 7, when the outer diameter dimension of the pipe 4 is equal to or greater than the width dimension of the unit steel sheet pile 5, or a plurality of pipes 4 are arranged in parallel. In such a case, the unit steel sheet pile 5 may be driven in the same manner by using the frame body 7 not only directly below the pipe 4 but also at a position adjacent thereto. In that case, the frame body 7 It is only necessary to increase the internal effective width dimension of the frame so that the frame body 7 can be displaced laterally with respect to the pipe 4 (in FIG. 7, the steel sheet piles directly below the pipe 4 and on both sides thereof are driven. The inner effective width dimension is equivalent to three steel sheet piles). Of course, the opening width dimension w of the opening 8 provided in the lower part of the frame body 7 needs to be increased according to the pipe diameter so that the pipe 4 can pass through.

  Although the embodiment of the present invention has been described above, the present invention is only applied to a case where a steel sheet pile is driven directly under a pipe when constructing an underground wall body as a countermeasure for preventing liquefaction of a supporting ground of an existing oil tank. First, when the frame body as described above is mounted on the outside of the obstacle so as to be movable up and down and driven through the frame body, not only the steel sheet pile but also various pile bodies can be used for various obstacles. It can be widely applied in general when driving directly below. Further, the pile driving machine used in the present invention is not limited to the vibro hammer, and an appropriate one may be used in consideration of various conditions such as the pile body to be driven, the ground condition, and the surrounding environment. Further, the work pit 10 and the temporary beam 11 in the above embodiment may be omitted if they are not necessary.

  In any case, the shape and size of the frame body, the required strength, the shape and size of the obstacle, its position, the type of pile driver, the pile driving method, etc. What is necessary is just to set optimally so that a pile body can be driven in the procedure similar to. Of course, as described above, the internal effective height dimension h of the frame body may be set according to the driving stroke of the unit pile body, but conversely, the internal effective height dimension h of the frame body is naturally due to some restrictions. Needless to say, if determined, the length of the unit pile body and the driving stroke thereof may be set accordingly.

FIG. 1 is a view showing a state in which a short unit steel sheet pile to be driven directly under piping is set according to an embodiment of the present invention. It is a figure which shows the condition which mounts | wears a frame body with a unit steel sheet pile via a holding tool. It is a figure which shows the condition which drives a steel sheet pile through a frame body same as the above. It is a figure which shows the state after driving in the same. It is a figure which shows the condition which adds a steel sheet pile and drives further. It is a figure which shows the state after construction completion same as the above. It is a figure which shows an application example same as the above. It is a figure which shows the example of the liquefaction prevention measure by the underground wall with respect to the support ground of the existing tank.

Explanation of symbols

1 Tank 2 Underground Wall 3 Liquefaction Layer 4 Piping (obstacle)
5 Unit steel sheet pile (unit pile)
6 Pile driver (Vibro hammer)
7 Frame body 8 Opening 9 Grasping tool 10 Work pit 11 Temporary beam 12 Steel sheet pile

Claims (1)

When driving piles such as steel sheet piles from above the obstacles such as pipes laid on the ground surface to the lower ground of the obstacles, the pile driving machine while adding short unit pile bodies below the obstacles It is a construction method of a pile body that is driven in sequentially by
The pile driving machine can be connected to the upper part, and the lower part has an opening that allows obstacles to pass through, so that it can be attached to the outside of the obstacle, and the internal effective height dimension is the driving stroke of the unit pile body Using the highly rigid frame body set above,
The frame body is connected to a pile driving machine and attached to the outside of the obstacle so that it can move up and down. A gripping tool is attached to the opening of the frame body and the unit pile body is gripped by the gripping tool. From the state where the obstacle is located in the lower part, the unit pile body is driven into the lower ground of the obstacle through the frame body by the pile driving machine until the obstacle reaches the inner upper part of the frame body. The construction of the pile body is characterized by interrupting the hammering when it is driven, and pulling up the frame body and adding a new unit pile body to the unit pile body after being driven, and holding it in the gripping tool and driving further Method.

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