JPH0615769B2 - Construction method of steel pipe mortar pile - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for implementing a steel pipe mortar pile that enhances the ground bearing capacity of soft ground.

[Prior art] Conventionally, in the execution of civil engineering and construction work, the structure which is to be carried out on the ground where the ground strength is insufficient, such as silt layer, loam landfill, etc., which has many water-containing layers and extremely low N value, has been used for many years. When it was difficult to stabilize the entire area, the normal pile driving work was taken to obtain the required bearing capacity. Concretely, there is a heavy equipment to the site, impacting the head of the steel pipe pile with a heavy hammer, driving, or press-fitting with hydraulic pressure, or a digging method, etc. Was increasing.

[Problems to be Solved by the Invention] However, in the above-mentioned public relations, there is a problem that noise and vibration are generated because the heavy equipment is used for driving the steel pipe piles, and the execution cost is high. There has been a problem that after many years, the steel pipe piles are corroded and the bearing capacity deteriorates.

The present invention has been made to solve the above-mentioned problems, and without using heavy machinery, there is no fear of noise and vibration pollution, and the cost is low and the steel pipe piles will corrode even after many years. It is intended to provide an enforcement method for steel pipe mortar piles that do not have any.

[Means to be Solved by the Invention] In the present invention, a joined steel pipe is formed of relatively short steel pipes so that they can be joined and fixed in the vertical direction, respectively, while a soil solidifying agent milk is formed on the outer peripheral surface of the steel pipe provided with a downward opening. A plurality of injection holes are provided for injection, and projecting pieces are provided in the lengthwise direction between the injection holes so as to have a diameter larger than that of the joined steel pipe to form a hole expansion portion, and The hole expansion part is fixed to the lower part of the joining steel pipe at the lowermost stage, and further, a plurality of connecting pipes are connected and fixed below the connecting pipe whose upper end is connected to the pressure-feeding hose of the soil solidifying agent milk, and each connecting pipe is connected. Through the jointed steel pipes joined to each other so that their ends face the inside of the hole expansion part, and the joints of the jointed steel pipes and the hole expansion part bonded and fixed thereto are integrated into the ground by a rotary pressurizing device. Then, excavate the ground that is larger than the joined steel pipe. , The soil solidifying agent milk is injected into the ground through the injection hole and the lower opening through the pressure injection nozzle fixed to the tip of the lowermost connecting pipe, and the soil solidifying agent milk is mixed with the local soil. At least fill the inside and outside of the joint public pipe, make the local soil into a slurry state, join and fix the jointed steel pipe upward at a predetermined depth, and further inject the soil solidifying agent milk after reaching the predetermined depth. A bulb-shaped milk layer is formed around the hole expansion part and the connecting pipe is removed, and after that the mortar support layer is formed inside and outside each bonded steel pipe by solidifying the soil-solidified milk, and at the same time the swelling around the hole expansion part occurs. By adopting the means of forming the mortar support layer having a part by connecting them,
The above problems were solved.

[Operation] According to the method of the present invention having the above-described structure, the mortar support layer is formed inside and outside each joined steel pipe by solidifying the soil-solidifying agent milk, and the mortar support layer having the bulb-shaped enlarged portion around the hole expansion portion is formed. Are connected to each other, and a strong friction is applied to each joined steel pipe by these mortar support layers to enhance the bearing capacity of the ground.

Example An example of the method of the present invention will be described with reference to the drawings.

According to the method of the present invention, among a plurality of joined steel pipes that are joined and fixed at the execution site, the tip of the joined steel pipe at the lowermost stage is fixed with a hole expansion portion having a projecting piece having a diameter larger than that of the joined steel pipe and an injection hole. Then, by using the rotary pressurizing device, the jointed steel pipes and the hole expanding portion joined and fixed to the pipes are integrally pressed into the ground, and the soil solidifying agent milk is injected into the ground through the injection holes of the hole expanding portion. By injecting, a ground having a diameter larger than that of the joined steel pipe is excavated by the projecting piece, the local soil is mixed with the soil solidifying agent milk, and further joined steel pipes are successively joined upward.
By rotating and pressurizing to a predetermined depth and continuously injecting the soil solidifying agent milk, a mortar support layer is formed inside and outside each joined steel pipe, and a mortar support layer having an enlarged part around the hole expansion part is connected. To form. Hereinafter, the method of the present invention will be described in detail.

Since the joined steel pipes 1 need to be joined one after another until reaching a predetermined depth at the working site, the medium-diameter steel pipe 2 is short, and it is not particularly limited, but preferably cut to about 1.5 m, Moreover, an upper vertical surface 3 is provided at the upper end of the steel pipe 2 in the longitudinal direction.
And a spiral-shaped upper inclined surface 4 reaching the counterclockwise circumferential surface from the bottom of the vertical surface 3 are continuously cut out to form a concave joint portion 5, and the upper vertical surface 3 is provided at the lower end of the steel pipe 2. A lower vertical surface 6 of the same length on the same axis, and a lower inclined surface 7 of a spiral having the same inclination angle as the upper inclined surface 45 reaching the counterclockwise circumferential surface from the bottom of the lower vertical surface 6. Is formed in a continuous manner by projecting a protruding joint portion 8, and a connecting steel pipe 9 is tightly fitted and fixed to the upper inner peripheral surface of the steel pipe 2 by projecting approximately half of the connecting steel pipe 9 upward. The inner peripheral surface of the lower joining portion 8b of the joining steel pipe 1b located at the upper stage is tightly fitted and fixed to the connecting steel pipe 9 which is projected substantially half upward from the joining steel pipe 1a located at the lower stage, and the concave joint portion 5a of the joining steel pipe 1a is fixed. The protruding joint portion 8b of the joined steel pipe 1b is placed on and closely attached to the joined steel pipe 1a, The tube 1b is for each fixed. In the following, the joined steel pipes 1c, ... Are formed so that they can be placed in close contact with each other and fixed.

Further, in order to be in close contact with the protruding joint portion 8a of the joint steel pipe 1a located at the lowermost portion of the joint steel pipe 1, the lower vertical surface 6 and the lower inclined surface 7 of the protruding joint portion 8 of the joint steel pipe 1 have the same length. Welded steel pipe 1 provided with a joint 12 formed by notching a vertical surface 10 and a spiral inclined surface 11 having a slant and an inclination angle at the upper end portion
A plurality of injection holes 14 for injecting the soil solidifying agent milk M are formed on the outer peripheral surface of the steel pipe 13 having the same downward diameter and a lower opening 13a, and the diameter is larger than that of the joined steel pipe 1. An arc-shaped projection piece 15 is provided between each of the injection holes 14 so as to project in the length direction of the number of floating sheets to form a hole expansion portion 16. The arc-shaped projecting piece 15 is such that the diameter of the hole expanding portion 16 is larger than that of the joined steel pipe 1, and its shape is not particularly limited, but is preferably as shown in FIG. It is preferable that the curved protrusion 15a is curved counterclockwise. Further, the hole expanding portion 16 is provided on the inner peripheral surface of the upper portion of the steel pipe 13 by projecting approximately half of the connecting steel pipe 9 upward, and the connecting steel pipe 9 of the hole expanding portion 16 is at the lowermost stage. Is tightly fitted and fixed to the inner peripheral surface of the lower portion of the aligned steel pipe 1a located at the position 1 and the protruding joint portion 8a of the joined steel pipe 1a is joined to the joint portion 1 of the hole expanding portion 16.
The bonded steel pipe 1a and the hole expanding portion 16 are fixed to each other by closely mounting them on the No. 2 pipe.

Then, the construction method using the joined steel pipe 1 and the hole expanding portion 16 configured as described above will be explained. At the working site, the joining steel pipe 1 and the hole expanding portion 16 are sequentially joined and fixed, respectively. It is necessary to provide a comparatively heavy rotary press-fitting device A for rotary press-fitting into the ground. This rotary press-fitting device A
Is not particularly limited, but may be as shown in FIGS. 1 and 2, for example. That is, the chucking parts 19 and 20 are vertically movably mounted on the column 18 fixed to the lower frame 17 and capable of rotatably holding the joined steel pipes 1 vertically. Rotating means 21 having a motor built in between 19 and 20
Are integrally fixed to each other to form the rotary press-fitting device A. Further, a pressure pump P for pumping the soil solidifying agent milk M is installed at the execution site, and a milk hose 22 is extended from the pressure pump P to a position above the joining steel pipe 1, and each tip of the milk hose 22 is joined to each joint. Each jointed steel pipe 1 and a connecting pipe 23 having a substantially copper length are connected to each other so as to penetrate through the steel pipe 1 and reach the hole expanding portion 16. Steel pipe 13 in opening 16
A pressure injection nozzle 24 for injecting the soil solidifying agent milk M from the lower opening 13a and the injection hole 14 is fixed.

Then, first, the joining steel pipe 1 is connected to the connecting steel pipe 9 on the hole expanding portion 16.
While tightly fitting and fixing the lower part of a, the joint steel pipe 1a located at the lowest stage is placed on the hole expanding portion 16, the projecting joint portion 8a is closely fixed to the joint portion 12, and the joint steel pipe 1a is rotated. A connecting pipe 2 for causing the soil-solidifying agent milk M to be pressure-fed by the pressure-injection device A with the locking portions 19 and 20.
3 is connected to the milk hose 22, and the soil solidifying agent milk M is injected from the pressure injection nozzle 24 into the injection hole 14 and the lower opening 13a.
When the joined steel pipe 1a is rotated by the rotary press-fitting device A to the clock method while pressure-injecting through the hole, the hole expanding portion 16
And the lower vertical surface 6 of the projecting joint 8a of the joined steel pipe 1a are in surface contact with each other, and the lower vertical surface 6 of the joined steel pipe 1a presses the vertical surface 10 of the hole expanding portion 16 in the clockwise direction. Therefore, the hole expanding portion 16 also rotates without separating.
By the rotary pressurizing device A, the joined steel pipes 1 and the hole expanding portions 16 joined to the joined steel pipes 1 are rotationally pressed into the ground, and the soil solidifying agent milk M is injected from the injection holes 14 of the hole expanding portions 16. When pressure is injected into the ground, each of the protrusions 15
The soil having a diameter larger than that of the joined steel pipe 1 is excavated by the above, and the soil solidifying agent milk M pressurized and injected is rotating.
6 is pressed against the local soil at the back of each projecting piece 15 and is mixed with the ground soil, and the soil mortar is in the form of a slurry, so the hole expanding portion 16 is relatively heavy. The hole expanding portion 16 and the joined steel pipe 1a can be easily rotated and pressed into the local soil. Then, when the bottom of the rotary press-fitting device A comes into contact with the ground, the rotation of the rotary press-fitting device A is stopped and the chucking state of the chucking portions 19, 20 with respect to the upper portion of the joined steel pipe 1a is released, and the second stage Place the bonded steel pipe 1b on the lowermost bonded steel pipe 1a, and fix it firmly.
Rotary pressurizing device A via the wire 26 by the winch 25
, The upper part of the joined steel pipe 1b is chucked by the chucking portions 19 and 20, and the next joining pipe 23 is joined to the joining pipe 23. Then, the soil solidifying agent milk M is sprayed and each joining steel pipe is operated in the same manner as described above. 1a, 1b, ... are rotated and pressure-injected, and when a predetermined depth is reached, the soil solidifying agent milk M is further injected to fill the inside of the hole expanding portion 16 and the periphery of the hole expanding portion 16 of FIG. The bulb-shaped milk layer 27 is formed, and then the connecting pipes 23, ... Since the arc-shaped projecting piece 15 of the hole expanding portion 16 projects outward from the joint steel pipe 1, the soil solidifying agent milk M is filled also in the outer periphery of the joint steel pipe 1, and the inside of the joint steel pipe 1 is also solidified. The soil solidifying agent milk is filled with the agent milk M, and the soil solidifying agent milk is solidified by finishing the chemical change in about 2 hours to 20 hours at the beginning and forms a mortar support layer 29 inside and outside each of the joined steel pipes 1 as well as the hole expanding portion. The mortar support layer 29 having the enlarged portion 28 is formed around the periphery of 16. The solidified mortar support layer 29 cooperates with the bulb-shaped bulge 28 so that the joined joint steel pipes 1 become steel pipe piles to add strong friction to the joint steel pipes 1 themselves to enhance the supporting force and to join the joint steel pipes. It plays the role of rust prevention inside and outside.

EFFECTS OF THE INVENTION Since the present invention is as described above, the soil-solidifying agent milk forms a mortar support layer inside and outside each jointed steel pipe, and a mortar support layer having a bulb-shaped bulge around the hole expansion part. The mortar supporting layer, which is formed, adds a strong friction to the jointed steel pipe itself and enhances the bearing capacity of the ground. In addition, since the joint steel pipe and the hole expansion part are completely covered with the mortar support layer, they are rust-proof and there is no risk of corrosion, and they are excellent in strength. There is no need for cost.

[Brief description of drawings]

The figure shows an example of the present invention, FIG. 1 is an overall schematic view showing a construction state, FIG. 2 is a side view of the same, and FIG. 3 is a partial cutout of a joined steel pipe and a hole expanding portion. Fig. 4 is an exploded view of the assembly, Fig. 4 is a vertical sectional view showing a state in which the joined steel pipe and the hole expanding portion are connected and fixed, Fig. 5 is a sectional view taken along the line I-I of Fig. 4, and Fig. 6 is a sectional view of the hole expanding portion. FIG. 7 is a vertical sectional view showing a sprayed state of the soil solidifying agent milk, and FIG. 7 is a vertical sectional view showing a state after completion of construction. In the figure, 1 is a joined steel pipe, 13 is a steel pipe, 13a is a downward opening,
14 is an injection hole, 15 is a projecting piece, 16 is a hole expansion part, 22 is a milk hose, 23 is a connecting pipe, 24 is a pressure injection nozzle, 27 is a bulb-shaped milk layer, 28 is an enlarged part, 29 is mortar. A support layer, A is a rotary pressurizing device, and M is a soil-solidifying milk.

Claims (1)

[Claims] 1. A relatively short steel pipe is formed so that the steel pipes can be joined and fixed in the vertical direction, respectively, while a plurality of injection holes for injecting soil-solidifying milk are formed on the outer peripheral surface of the steel pipe having a lower opening. In addition, a projecting piece is projecting in the length direction between each of the injection holes so as to have a diameter larger than that of the joined steel pipe to form a hole expanding portion, and the hole expanding portion is joined at the lowest stage. It is fixed to the lower part of the steel pipe, and further, a plurality of connecting pipes are connected and fixed below the connecting pipe whose upper end is connected to the pressure-feeding hose for soil solidifying agent milk, and the connected connecting pipes penetrate the joined steel pipes. Then, the tip is exposed to the inside of the hole expansion part, and each joined steel pipe and the hole expansion part joined and fixed to this are integrally pressed into the ground by a rotary press-fitting device, and the diameter is larger than that of the joined steel pipe. While excavating the ground, the tip of the lowest connecting pipe Through the pressure injection nozzle fixed to the, the soil solidifying agent milk is injected into the ground from the injection hole and the lower opening, and the soil solidifying agent milk is mixed with the local soil to fill the inside and outside of the joined steel pipe, The local soil is made into a slurry, and the joined steel pipes are joined and fixed upward until it reaches a predetermined depth, and after reaching the predetermined depth, the soil solidifying agent milk is further injected to form a bulb-shaped milk around the hole expansion part. A layer is formed and the connecting pipe is removed, and then the soil solidifying agent milk is solidified to form a mortar support layer inside and outside each joined steel pipe, and a mortar support layer having an enlarged part around the hole expansion part is connected. A method for enforcing steel pipe mortar piles characterized by being formed by forming.