JP2007186946A - Underground anchor driving-installation construction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an underground anchor driving-installation construction method which suppresses a jet of grout caused by a force of pressurized water, and saves the work of pushing in a jet preventing stopper that suppresses the jet. <P>SOLUTION: In the underground anchor driving-installation construction method, pipes 1 connected in a multi-tier arrangement are driven into a drilled underground hole, and an anchor tension member 2 is inserted into the pipes. As grout is pressure-transferred into the pipe, the whole of the pipe is pulled out gradually to separate the pipes 1 sequentially from the pipe in the upper most tier exposed to the ground surface. After each pipe is pulled out, the grout is solidified to fix the anchor tension member. The jet preventing stopper which has a grout passage 3b with a check valve and a seal portion in slidable contact watertightly with the inner surface of the pipe is attached to the ground side front end of the anchor tension member before the pressure-transfer of the grout. The whole of one pipe is pulled out to locate the jet preventing stopper in the other pipe at the lower tier, and then the pipe at the uppermost tier is separated, at which a jet of the grout is prevented by the check valve 3d of the jet preventing stopper after the whole of the pipe is pulled out. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an underground anchor placing method.

  Conventionally, a pipe connected in multiple stages to a drilled underground hole is driven and an anchor tension member is inserted into the pipe, and the pipe is gradually pulled up while pumping the grout from above the pipe, and separated from the top pipe in order. An underground anchor placing method is known in which the grout is hardened in the underground hole and the anchor tension member is fixed to construct the underground anchor. By the way, in this technology, the grout pumped during the separation of the pulled pipe is easily ejected from the pipe in the underground hole due to the underwater pressure etc., and anchor anchoring of the anchor tension member has become incomplete due to insufficient grout. .

Therefore, a spout prevention plug having a structure with a grout passage with a check valve inside and a seal portion provided around the outer periphery is fitted into the upper part of the pipe, and the grout is removed from the opening of the spout passage of the spout prevention plug. The underground anchor placement method is to repeat the process of pulling up the entire pipe by one stage while pumping, pushing the spout prevention plug on the pulled-up uppermost pipe into the lower pipe, and then separating the uppermost pipe. This is proposed in Patent Document 1. However, in this technique, when the pipe is pulled up, the blowout stopper comes inside the uppermost pipe, so that it is necessary to push the blowout stopper into the lower pipe just before the separation, which requires work.
JP-A-8-81955

  The problem to be solved by the present invention is to solve these conventional problems, suppress the ejection of the grout due to the pressurized hydraulic force, and eliminate the operation of pushing the ejection preventing plug for suppressing the injection of the underground anchor. To provide a construction method.

The configuration of the present invention that solves this problem is as follows.
1) Drive pipes connected in multiple stages into the ground and insert anchor tension members into the pipes, gradually pulling up the entire pipe while pumping grout into the pipes, step by step from the uppermost pipe exposed on the ground. In the underground anchor placement method, where all the pipes are pulled up and then the grout is hardened and the anchor tension member is fixed to construct the underground anchor, the grout passage with a check valve inside A spout stopper having a seal portion that is slidably watertight with the inner surface of the pipe is attached to the head of the anchor tension member before grouting, and a spout stopper plug is placed in the lower pipe of the uppermost pipe. After pulling up the entire pipe so that it can be placed, the uppermost pipe is separated, and when the pipe is separated, the check valve of the blowout prevention plug prevents the grouting Underground anchor placement method 2), wherein the entire pipe can be pulled up, and the spout prevention plug forms a connecting portion connected to the head of the anchor tension member at the lower end portion of the plug body. 1) description above, wherein a check valve that penetrates the grout passageway from the upper central portion of the connecting portion along the outer peripheral position of the connection portion and blocks the outflow of the grout in the middle of the grout passageway is provided. It is in the underground anchor placement method.

  According to the present invention, since the ejection preventing plug is attached to the head of the anchor tension member, the ejection preventing plug does not come inside the pipe when the pipe is pulled up. It is possible to construct an underground anchor with good workability in a short time by omitting the work of pushing into the pipe.

  In the present invention, the grout includes a cement system and a synthetic resin system, and the cement system includes ordinary Portland cement and early-strength Portland cement, and the cement is paste or milk. Materials that do not corrode by grout, such as metal and plastic, are used for the pipe and spout stopper. As the anchor tension member, a PC steel wire, a PC steel strand, a deformed PC steel wire, a PC steel rod, or a deformed PC steel rod is used. Embodiments of the present invention will be specifically described below with reference to the drawings.

  FIG. 1 is an explanatory view of an ejection preventing plug of the embodiment, FIGS. 2 and 3 are process diagrams showing the construction of the underground anchor of the embodiment, FIGS. 4 and 5 are explanatory views showing the passage of the grout of the embodiment, and FIG. It is process drawing which shows construction of the underground anchor of an Example. In the figure, 1 is a pipe, 2 is an anchor tension member, 2a is a head, 3 is an ejection stopper, 3a is a connection part, 3b is a grout passage, 3c is a spring, 3d is a check valve, 3e is a seal part, 3f is a connecting part, 4 is a grout pressure feeding tool, 4a is a pressure feeding pipe, 5 is a pedestal, 6 is a bearing plate, 7 is a fixing member, 8 is a covering member, G is a ground, H is an underground hole, and M is a grout. .

  As shown in FIG. 1, the spout prevention plug 3 of the present embodiment has an outer diameter that can be inserted into the pipe 1, and a connection portion 3 a that is screwed with the head portion 2 a of the anchor tension member 2 is formed at the lower end portion. A grout passage 3b through which the grout M passes from the outer peripheral position of 3a along the upper central portion is formed, and the grout M passes through the grout M so as to pass the grout M only in one direction by the biasing force of the spring 3c above the grout passage 3b. A check valve 3d that closes the passage 3b so as to be openable and closable is attached, a seal portion 3e that is slidably watertight with the inner surface of the pipe 1 is provided on the outer peripheral surface, and a pumping tube 4a of the grout pumping tool 4 at the upper end. A connecting portion 3f to be screwed is provided.

  Explaining the process of constructing the underground anchor of this embodiment, as shown in FIG. 2 (a), the underground hole H having a predetermined depth is drilled in the ground G with a drill machine, and the pipe 1 having a predetermined length is screwed. Combined in multiple stages and driven into the underground hole H. Next, as shown in FIG. 2 (b), an anchor tension member 2 made of a PC steel rod is placed in the pipe 1 that has been driven in, and the connection portion 3 a of the ejection preventing plug 3 is attached to the head 2 a of the anchor tension member 2. It attaches by screwing and the seal | sticker part 3e of the ejection stopper 3 is closely_contact | adhered to the inner surface of the pipe 1. FIG.

  Next, as shown in FIG. 3 (a), the grout pressure feeder 4 is attached to the end of the uppermost pipe 1 and the pressure feed pipe 4a is screwed with the connection portion 3f of the ejection preventing plug 3, and supplied from the outside. A grout M made of mortar is pumped into the pipe 1. At this time, as shown in FIGS. 4 and 5, the check valve 3 d opens the grout passage 3 b with the flow pressure and the grout M passes, flows into the pipe 1 at the bottom of the underground hole H, and flows through the pipe 1. Fill with Grout M. Thereafter, as shown in FIG. 3B, the multistage pipe 1 is gradually pulled up to separate and remove the uppermost pipe 1. At this time, the grout M pumped into the pipe 1 is prevented from backflow by the check valve 3d of the ejection preventing plug 3, and the grout M does not spout outside during separation.

  Next, as shown in FIG. 6A, when all the pipes 1 that have been driven are pulled up, the ejection preventing plug 3 is also removed from the anchor tension member 2. Then, as shown in FIG. 6 (b), a base 5 is formed on the head 2 a of the anchor tension member 2 exposed on the ground surface, and is fixed by the fixing tool 7 through the bearing plate 6, and the head is fixed by the covering member 8. A ground anchor is constructed by covering. Thus, according to the present embodiment, since the ejection preventing plug 3 is attached to the anchor tension member 2, the ejection preventing plug 3 does not come into the pipe 1 when the pipe 1 is pulled up, and immediately before the separation. It is possible to construct an underground anchor with good workability in a short time by omitting the operation of pushing the spout prevention plug 3 into the lower pipe 1.

  Another example of the embodiment shown in FIG. 7 is an example of an ejection preventing plug when a PC steel wire (strand) is used as the anchor tension member. FIG. 7 is an explanatory view of an ejection preventing plug of another example of the embodiment. In the figure, 9 is an anchor tension member, 10 is a coupler, 10a is an insertion hole, and 11 is a wedge. In another example of the embodiment shown in FIG. 7, the anchor pulling member 9 is inserted into the insertion hole 10 a of the coupler 10, the head is crimped with the wedge 11, and this is screwed into the lower end portion of the ejection preventing plug 3. Yes. A plurality of grouting passages 3 b are opened on the outer periphery of the ejection preventing plug 3. In other respects, the reference numeral, the configuration, and the operational effects are the same as in the embodiment.

  The underground anchor placing method according to the present invention is useful for constructing an anchor at a place where underground water, pumped grout, and mud sand easily flow into the pipe that has been driven in.

It is explanatory drawing of the ejection prevention stopper of an Example. It is process drawing which shows construction of the underground anchor of an Example. It is process drawing which shows construction of the underground anchor of an Example. It is process drawing which shows passage of the grout of an Example. It is process drawing which shows passage of the grout of an Example. It is process drawing which shows construction of the underground anchor of an Example. It is explanatory drawing of the spout prevention stopper of the other example of an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pipe 2 Anchor tension | tensile_strength member 2a Head part 3 Ejection prevention plug 3a Connection part 3b Grout passage 3c Spring 3d Check valve 3e Seal part 3f Connection part 4 Grout pumping tool 4a Pressure feed pipe 5 Base 6 Supporting plate 7 Fixing member 8 Covering member 9 Anchor tension member 10 Coupler 10a Insertion hole 11 Wedge G Ground H Underground hole M Grout

Claims (2)

  The pipes connected in multiple stages are driven into the ground and anchor tension members are inserted into the pipes. While the grout is pumped into the pipes, the entire pipe is gradually pulled up and separated one by one from the uppermost pipe exposed on the surface. In the underground anchor placing method in which the grout is hardened by pulling up all the pipes and the anchor tension member is fixed and the underground anchor is constructed, it has a grout passage with a check valve inside. In addition, a spout stopper provided with a seal portion that is slidably water-tight with the inner surface of the pipe is attached to the head of the anchor tension member before grouting, and a spout stopper plug is disposed in the lower pipe of the uppermost pipe. After pulling up the entire pipe, the uppermost pipe is separated, and when the pipe is separated, the check valve of the blowout prevention plug prevents grouting from the pipe. Characterized in that to be able to pull up the whole ground anchoring hitting 設工 method.   A spout prevention plug forms a connection portion connected to the head of the anchor tension member at the lower end portion of the plug body, penetrates the grout passageway from the upper center portion of the plug body along the outer peripheral position of the connection portion, The underground anchor placing method according to claim 1, wherein a check valve for blocking outflow of the grout is attached in the middle of the passage.

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