JPH04272388A - Bottom water cut-off method of vertical shaft - Google Patents

Abstract

PURPOSE:To allow the bottom concrete resist pressure acting on the bottom surely to cut-off water completely. CONSTITUTION:After the construction of a vertical shaft 4, boring guide pipes 5 inserting and fitting rising and falling pipes 5' into the front ends of them so that they are capable of rising and falling are erected, and boring rods 9 are inserted in the guide pipes 5 to bore holes in the bottom ground. Tension members are inserted into the holes from above, and fixed anchors 11 are made by solidifying the tension members with hardening materials filled in the holes. After that, the tension members 10 are strained and, at the same time, the rising and falling pipes 5' of the guide pipes 5 are pulled up to a required height to expose the tension members 10. Underwater concrete is placed on the bottom ground downward of them to fix exposed parts of the tension members 10 to the bottom concrete slab 15. A temporary construction in the vertical shaft 4 is removed and, at the sane time, the inside thereof is drained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-stopping method for the bottom of a shaft, and more particularly to a water-stopping method for placing underwater concrete at the bottom of a shaft.

0002

[Prior Art] Conventionally, in order to prevent boiling, slab bulging, etc. that occur when excavating inside a shaft, it has been common practice to extend the penetration of earth retaining walls, and If there is no suitable impermeable ground, water at the bottom of the shaft will be stopped by ground improvement.

Known ground improvement methods for stopping water at the bottom of a shaft include a jet grouting method, a chemical injection method, and the like, which improve the ground prior to excavating the inside of the shaft.

However, in the above-mentioned conventional ground improvement method, the strength of the improved body is low, so it is necessary to increase the thickness of the improved body in order to stop water at the bottom of a deep shaft that is subject to large uplift pressure. There was a problem in that the quality of the improved radius, strength of the improved body, permeability coefficient, etc. by boring varied widely, and there was a lack of certainty.

[0005] Furthermore, as the depth of boring increases, the drilling position tends to deviate from the predetermined location due to drilling accuracy, which may result in insufficient wrapping of the improved body and the possibility of not being able to ensure water stoppage. The problem was that a large safety factor had to be taken into consideration.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to develop a reliable bottom water stoppage method that does not involve soil improvement, in view of the instability of the bottom water stoppage method due to ground improvement.

[0007]

[Means for Solving the Problems] In order to solve the above-mentioned conventional problems, the present invention provides a vertical shaft 4 with a continuous underground wall 1 as a side wall.
After constructing a vertical shaft 4 by submerging an open caisson 3 by excavating the inside of the shaft underwater, or by sinking an open caisson 3 while performing internal excavation, a boring guide pipe 5 having a lifting pipe 5' inserted into the tip so as to be freely raised and lowered is erected. , this guide pipe 5
Insert the boring rod 9 inside to drill a hole in the bottom ground,
By inserting the tensile material 10 into the hole from above and solidifying it with the hardened material filled in the hole, the fixing anchor 11
After creating the tension member 10, the tension member 10 is tensed, and the elevator pipe 5' of the guide pipe 5 is raised to the required height to expose the tension member 10, and underwater concrete is placed on the bottom ground below it. The present invention proposes a water-stopping method for the bottom of a shaft, in which the exposed portion of the tensile material 10 is fixed on a concrete plate 15, temporary structures inside the shaft 4 are removed, and the interior is drained.

[0008]

[Operation] The bottom concrete plate 15 is fixed to the anchor 11
Since it is supported under tension via the tension member 10,
Resists the uplift pressure of the ground and reliably prevents boiling and blistering.

[0009]

[Embodiment] First, as shown in FIG. 1, the inside of a shaft whose side walls are made up of continuous underground walls 1 is excavated underwater with a drilling device 2 as shown in FIG. 2, or with a drilling device 2 as shown in FIG. Each vertical shaft 4 is constructed by sinking an open caisson 3 while performing internal excavation.

Inside this shaft 4, a boring guide pipe 5, in which a lifting pipe 5' which can be raised and lowered as shown in FIG. , the upper end is supported by a guide pipe hanging jig 7.

[0011] At this time, reinforcing bars, steel materials, etc. for reinforcing the bottom concrete, which will be described later, are installed.

Next, as shown in FIG. 5, a boring rod 9 of a boring machine 8 is inserted into the guide pipe 5, and the bottom ground is bored for an anchor. The fixing anchor 11 is created by inserting the fixing anchor 11 and filling it with a hardened material such as concrete.

Then, as shown in FIG. 6, the tensile member 10 is tensioned at the tensile part 12 at its upper end, and the elevator pipe 5' of the guide pipe 5 is pulled up to a required height, exposing the tensile member 10 at this pulled-up portion. .

[0014] Furthermore, around this exposed portion of the tensile material 10, a fixing material 13 is placed in advance to strengthen the fixation of the concrete.
It is desirable to attach the following.

Next, as shown in FIG. 7, the tremie tube 14
By this, underwater concrete is integrally cast at the bottom of the shaft up to the lower end of the elevator pipe 5' to create a bottom concrete plate 15, and the exposed portion of the tensile member 10 under tension is fixed to this.

After the concrete in the bottom concrete plate 15 has hardened, the inside of the shaft 4 is drained, temporary structures inside the shaft such as the guide pipe 5, spacer 6, guide pipe hanging jig 7, etc. are removed, and the water level is further lowered. After lowering, the unnecessary tensile material 10 on the upper part of the bottom concrete plate 15 is cut off to complete the construction as shown in FIGS. 8 and 9.

[0017]

[Effects of the Invention] Even if there is no suitable impermeable ground below the flooring depth of the shaft, it is not necessary to install the earth retaining wall for a long time to prevent boiling, slab bulging, etc.

[0018] Since there is no pour seam in the bottom concrete plate, water leakage due to insufficient wrapping of the improved body does not occur as in the case of soil improvement.

[0019] The bottom concrete slab has less variation in quality such as strength and water-stopping properties than an improved body made by soil improvement.
Highly reliable.

[0020] The bottom concrete slab is supported by anchors via tensile members under tension, and the uplift force acting on the bottom is resisted, so the uplift force is resisted only by the concrete's own weight and the shear resistance of the shaft side wall. It is economical because the concrete thickness can be reduced compared to conventional methods.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a side wall of a shaft according to the present invention constructed from a continuous underground wall.

FIG. 2 is a sectional view showing the state of excavation of a vertical shaft using a continuous underground wall according to the present invention.

FIG. 3 is a sectional view showing how the shaft according to the present invention is constructed using an open caisson.

FIG. 4 is a sectional view showing the construction state of the present invention.

FIG. 5 is a sectional view showing the construction state of the present invention.

FIG. 6 is a sectional view showing the construction state of the present invention.

FIG. 7 is a sectional view showing the construction state of the present invention.

FIG. 8 is a sectional view showing one aspect of the present invention in a completed construction state.

FIG. 9 is a sectional view showing another aspect of the present invention in a completed construction state.

[Explanation of symbols]

1. Continuous underground wall 2 Drilling equipment 3 Open caisson 4 Vertical shaft 5 Guide pipe 5’ Elevator pipe 6 Spacer 7 Guide pipe hanging jig 8. Boring machine 9 Boring rod 10 Tensile material 11 Fixation anchor 12 Tension area 13 Fixing material 14. Tremy tube 15 Bottom concrete board

Claims (1)

[Claims] [Claim 1] A step of constructing a vertical shaft whose interior is excavated underwater to the bottom, and a guide pipe having a lift pipe attached to the lower end that can be raised and lowered freely from the bottom to the top of the shaft, and boring inside the guide pipe. A step of inserting a rod to drill a hole in the bottom ground; a step of inserting a tensile material into the hole from above and solidifying it with a hardened material filled in the hole to create a fixing anchor; a step of tensioning the tensile material, raising the lift pipe of the guide pipe to a required height, placing underwater concrete on the bottom ground below the tensile material, and fixing the tension material on the bottom concrete plate; A method for stopping water at the bottom of a shaft, which comprises the steps of removing temporary structures inside the shaft and draining the inside of the shaft after the board has hardened.