JP3423705B2 - Construction method of large diameter improved soil column - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved soil column which has been chemically solidified by adding a solidifying material to the excavated soil at the current position of the ground, mechanically mixing and stirring it. The present invention relates to a method for building a large-diameter improved soil column having an improved diameter exceeding, for example, 1.5 m in a ground improvement method for building. 2. Description of the Related Art In a deep mixing ground improvement method, an excavation shaft is generally provided on a base machine so as to be rotatable and excavated, a stirring blade, a solidified material discharge port and the like are provided at the tip of the excavation shaft. Using a drilling and stirring device, for example, when the drilling shaft reaches a predetermined depth by rotating and drilling, the drilling and mixing and stirring is performed while discharging the solidified material in a slurry state, and when it reaches the bottom end, the drilling shaft is reversed. It is mixed and stirred again while pulling up, and an improved earth pillar is being built in the ground. [0003] When an improved earth column with a large diameter is constructed using such an excavating and stirring device, the length of the excavating blade and the stirring blade can be simply increased. On the other hand, regarding the discharge of the solidified material slurry, if the improved diameter is up to about 1.2 m to 1.5 m, the solidified material slurry such as cement milk is discharged at a low pressure from the discharge port provided on the side surface at the tip of the excavation shaft. With this configuration, it is possible to uniformly disperse and stir and mix in the cross section of the borehole.
However, in order to construct a large-diameter improved soil column having a diameter exceeding 1.5 m, it is important to consider that the solidified material slurry is uniformly distributed over the entire cross section of the excavation hole. Various types of excavating and stirring devices have been developed in the past. As a technique for uniformly dispersing the solidified material slurry over the entire cross section of excavated soil, for example, the following technology has been proposed. . Drilling blade guide system [0005] As described in, for example, JP-A-7-76826 (cutting mixer), a downward gutter-shaped cutter spoke and a large number of cuts arranged in the gutter are provided at the tip of a drilling shaft. A drilling wing consisting of a blade is attached, and the cement milk supplied in the supply pipe in the drilling shaft is received by the diffusion plate provided at the tip of the drilling shaft and simultaneously diffuses horizontally, and this cement milk is guided in a gutter-like cutter spoke. It leads to the space and spreads the cement milk throughout the cutter spokes. [0006] A method of extending the position of the discharge port to a digging blade or a stirring blade, for example, in Japanese Patent Application Laid-Open No. 62-273316 (ground improvement device), a diametrical direction is applied to the stirring blade or the digging blade at the tip of the digging shaft. A large number of discharge ports are provided at intervals. In JP-A-6-146264 (co-rotation prevention forced stirring device), a supply pipe for supplying cement milk extends to a drilling wing, and an injection nozzle at the tip thereof is located at a radially central portion of the drilling wing. Like that. [0007] The above-mentioned excavation wing guide system is designed to uniformly spread the cement milk spread horizontally by the diffusion plate over the entire cross section using the excavation wing as a guide. It is a mechanism that cannot directly control cement milk. Therefore, although the cement milk may be stirred and mixed uniformly over the entire cross section, it has a disadvantage that it may not work well, and lacks certainty.
It is difficult to apply to large-diameter improved soil columns. In addition, the above-described method in which a number of discharge ports are provided in the stirring blade has a disadvantage that the discharge amount from each discharge port decreases as the distance from the excavation axis decreases, and uniform stirring and mixing cannot be performed. Furthermore, in the method in which the injection nozzle is provided at the center of the excavation wing, cement milk is uniformly filled in the outer portion of the excavated soil cross section, but conversely, cement milk is not supplied in the inner portion, and the entire improved soil column is There is a disadvantage that it results in a non-uniform improvement. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to ensure that a solidified material slurry is uniformly and uniformly applied to an excavated soil cross section even for a large-diameter improved soil column. Digging that can be spread and excavated by the excavation wing
An object of the present invention is to provide a construction method capable of easily constructing a uniform large-diameter improved earth column over the entire cross-section of a shaved soil. According to the present invention, there is provided a drilling / stirring apparatus provided with a drilling blade and a stirring blade at a tip portion of a drilling shaft. In the method for constructing an improved earth column, a discharge port is provided at a lower portion and an upper portion at a tip portion of a drilling shaft, and the lower discharge port is provided with a discharge port provided at a side portion at a tip portion of the drilling shaft, a cutting blade or a stirring blade. And a discharge port provided at a radially intermediate portion of the excavator, the discharge port at the radially intermediate portion is oriented in a direction perpendicular to the blade extending direction in plan view, and further, the upper discharge port is formed by a drilling shaft. And a discharge port provided at a radially intermediate portion of the stirring blade, and the discharge port at the radially intermediate portion is in a direction perpendicular to the blade extending direction in plan view. So that the lower discharge port A large-diameter excavation and stirring device is provided in which an independent solidified material liquid supply passage is connected to each of the outlet and the radially intermediate outlet and the side outlet of the upper outlet and the radially intermediate outlet. When the specified depth is reached ,
In the plan view of the discharge port on the side of the excavation shaft and the middle part in the radial direction,
Perform excavation and mixed stirring while ejecting an ejection outlet or al solidifying material solution (cement milk, etc.) facing the direction perpendicular to the extension direction, and reaches the lowermost end, the supply of the solidifying material liquid from the lower discharge port Stop and move the discharge port on the side of the excavation shaft of the upper discharge port and the direction perpendicular to the blade extension direction in plan view of the radially intermediate portion.
The discharge port or we solidified material liquid that faces toward the (cement milk, etc.) injection
By performing the raising and mixed stirring while out, drilling
Solidified material over the entire cross section of excavated soil excavated with wings
Make sure that the liquid is evenly and
Large-diameter improvement over the entire cross section of excavated soil
This is a method for constructing a large-diameter improved earth pillar, which is characterized by building a pillar. The method of discharging the solidified material liquid includes a method in which the liquid is discharged from a lower discharge port at a lower portion (in the vicinity of a digging wing) at a tip portion of the digging shaft only when the digging / stirring head penetrates (when digging and stirring), and when a drawing is performed. A method of discharging from the upper discharge port in the upper part (near the uppermost stirring blade) at the tip of the excavation shaft only at the time of ascent and stirring, or discharging at both the time of penetration and the time of withdrawal (the lower discharge port at the time of penetration) Therefore, there is a method of discharging from the upper discharge port at the time of drawing out). The present invention is a method of discharging both at the time of penetration and at the time of withdrawal (discharge from the lower discharge port at the time of penetration and from the upper discharge port at the time of withdrawal). Use the lower discharge port (discharge port on the side surface, discharge port in the radial middle part of the excavator blade or the stirring blade) provided at the lower part (such as the position of the excavator blade or the lowermost stirring blade) at the tip of the shaft. , At the time of withdrawal, an upper discharge port (a discharge port on a side portion,
The discharge port at the radially intermediate portion of the stirring blade will be used. The lower discharge port and the upper discharge port may be provided in the vicinity of the excavation axis and the radial center of the excavation blade or the stirring blade. It is preferable to provide it at a radially intermediate portion of the stirring blade from the viewpoint of the structure and the like. In addition, independent solidified material liquid supply passages are connected to the inner discharge port on the excavation axis side and the outer discharge port in the middle portion of the blade, respectively.
The solidified material liquid can be individually supplied from the solidified material liquid tank outside the excavating and stirring device, and the solidified material liquid is ejected from each discharge port at an arbitrary discharge amount. In the above construction, the solidified material liquid is simultaneously ejected from the inner discharge port on the side surface of the excavation shaft and the outer discharge port on the intermediate portion of the blade, and the solidified material slurry (solidified material liquid) is discharged from the inner discharge port. Is sufficiently supplied to the inside of the excavated soil near the excavation axis,
The solidified material slurry (solidified material liquid) from the outer discharge port reaches the surrounding portion of the excavated soil and is sufficiently supplied to the outer portion of the excavated soil. Further, since an independent solidified material liquid supply passage is connected to each of the discharge ports, the discharge amount of the solidified material liquid from each of the discharge ports is arbitrarily set according to the size of the diameter, so that each of the discharge ports predetermined discharge amount can be reliably discharged from excavation, even during agitation, increased, even at the time of stirring, the solidifying material liquid in improved soil columns having a large diameter as a diameter of more than 1.5 m, the drilling blade Can be uniformly and reliably spread over the entire cross-section of the excavated soil excavated at . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in the drawings. FIG. 1 shows a tip portion of a drilling shaft in a large diameter drilling and stirring device used in the construction method of the present invention,
FIG. 2 shows the cross section. In FIG. 1, a digging and stirring head A is attached to a tip portion of a digging shaft body (not shown),
An excavating shaft 1 of the excavating and stirring head A is supported, in order from the bottom, on an excavating bit 2 at the tip of the excavating shaft, two excavating blades 3 having a plurality of excavating blades, and a rotatable shaft with respect to the excavating shaft 1. A co-rotation prevention blade 4 for preventing co-rotation of soil in a fixed state and a plurality of stages of stirring blades 5 are attached. The excavating shaft main body has a rotary driving device at an upper portion, and is supported by a leader of the device main body via the rotary driving device so as to be vertically movable, and the rotary driving device is raised and lowered by a hanging wire rope. The excavation / stirring head rotates and excavates and descends, and also lifts and rises (not shown). In such an excavating and stirring head A, as shown in FIGS. 1 and 2, a discharge port 10 is provided on a side surface at the lower end of the excavating shaft 1, and a discharge port 11 is provided on one of a pair of excavating blades 3.
And the lower discharge port is constituted by the inner excavation axis discharge port 10 and the outer excavation blade discharge port 11. Drilling shaft discharge port 10
Is provided at one location between the mounting portions of the pair of digging wings 3, and the digging wing discharge port 11 is formed at the tip of a horizontal supply pipe 12 attached to the inclined back surface of the digging wing 3 from the digging shaft 1. And one location at the radial center of the excavation wing 3. In this embodiment, the discharge directions of the excavation shaft discharge port 10 and the excavation blade discharge port 11 are set to be opposite to each other (see FIG. 2). Drilling shaft discharge port 10 and drilling blade discharge port 11
The solid supply material slurry (solidification material liquid) supply passages 13 and 14 are respectively connected to the horizontal supply pipe 12. The solidified material slurry (solidified material liquid) supply passages 13 and 14 are a supply pipe or a supply hole provided in the excavation shaft 1 and the excavation shaft main body, and are connected via a swivel, a hose, or the like provided at an upper end portion of the excavation shaft main body. Then, it is connected to a pump of a mixing plant installed outside, so that a solidified material slurry (solidified material liquid) can be individually supplied to each of the discharge ports 10 and 11. Further, two pumps are installed, and a hose for the excavation shaft discharge port 10 and a hose for the excavation blade discharge port 11 are connected to each pump via a flow rate control valve. , 11 are set and adjusted. The excavation shaft discharge ports 10 may be provided as a pair on opposing side surfaces of the excavation shaft 1. Drilling wing discharge port 11
May be provided on the other excavating wing 3 or the excavating wing 3
May be arranged at intervals in the radially intermediate portion of the above. The excavation blade discharge port 11 is provided at the lowermost stirring blade 5.
_-1 through a horizontal supply pipe 12 ', and the lower discharge port may be constituted by the stirring blade discharge port 11' and the excavation shaft discharge port 10. Furthermore, eliminating the drilling shaft discharge port 10, the drilling shaft discharge port 10 on the side surface of the excavating shaft 1 in the vicinity of the lowermost stirring blade 5 _-1 'to provided, the drilling shaft discharge port 10' and the stirring blade discharge port 11 ' The lower discharge port may be constituted by the above. In addition, the excavation shaft discharge ports 10 and 10 ′ are eliminated, and the excavation blade discharge port 11 or the stirring blade discharge port 11 ′ is provided in the vicinity of the excavation shaft 1 and the radial center of the excavation blade 3 or the stirring blade 5. Is also good. When a plurality of excavation shaft discharge ports 10, 10 'or blade discharge ports 11, 11' are provided, a solidified material slurry (common to the plurality of discharge ports 10, 10 'or 11, 11') is used. A solidified material slurry (solidified material liquid) may be supplied from a supply passage, or a plurality of discharge ports 1 may be supplied.
An independent solidification material slurry (solidification material liquid) supply passage may be connected to 0 or 11, respectively. Although only the configuration of the lower discharge port used for excavation and agitation in the present invention has been described above, when the discharge method at the time of extraction or the discharge method at the time of penetration or extraction is performed as in the present invention, the upper discharge port is used. Discharge ports are provided. Like the lower discharge port, the upper discharge port has a digging shaft discharge port 10 ″ provided on the side surface of the digging shaft 1 slightly above the mounting portion of the uppermost stirring blade _5-4 , and the stirring blade _5-4. Stirring impeller discharge port 11 "provided through a horizontal supply pipe 12" at the radially intermediate portion of
It consists of. In addition, in the case of the excavating shaft discharge port 10 "and the stirring blade discharge port 11", similarly to the lower discharge port, a plurality of the excavation shaft discharge ports are arranged at appropriate upper positions. Various modes can be adopted, such as providing the stirring blade near the excavation axis and at the center in the radial direction. Also, the excavation shaft discharge port 10 ″ and the stirring blade discharge port 1
The solidified material slurry (solidified material liquid) supply passages 13 "and 14" of 1 "are respectively independent of the solidified material slurry (solidified material liquid) supply passages 13 and 14 of the lower discharge port. In this case, for example, 13 ″ and 13 are 2
13 ″ communicates with the drilling shaft discharge port 10 ″, 13 communicates with the drilling shaft discharge port 10, and 13 ″ and 13 are connected by a flow path switching device provided at the upper part of the drilling shaft body. The upper excavation shaft discharge port 10 ″ and the lower excavation shaft discharge port 10 are arbitrarily selected, and a predetermined amount of solidified material slurry (solidified material liquid) can be ejected from each of them. 1
The same applies to 4 "and 14. In the above configuration, the diameter is 1.5.
For improved soil columns exceeding m, deep ground improvement is performed by the following procedure, for example. (1) The discharge amount from each of the discharge ports 10 and 11 is set according to the diameter of the improved earth pillar to be built,
The drilling shaft is lowered while rotating. (2) When a predetermined depth is reached, solidification material slurry (solidification material liquid) is simultaneously ejected from each of the discharge ports 10 and 11, and excavation and mixing and stirring are performed. (3) When reaching the lowermost end, the lower discharge port 1
0, 11 is switched to the upper discharge ports 10 ″, 11 ″, and while the drilling axis is reversed and lifted, the solidified material slurry (solidified material liquid) is simultaneously ejected from the upper discharge ports 10 ″, 11 ″ and mixed again. Stir. When the injection, agitation, and withdrawal of the ground improvement section are completed, the ejection of the solidified material slurry (solidified material liquid) from each of the discharge ports 10 "and 11" is stopped, the excavation shaft is rotated while being lifted, and the construction is completed. . A solidified material slurry (solidified material liquid) is ejected from the inner excavating shaft discharge port 10 or 10 "and the outer excavating blade discharge port 11 or 11" at a predetermined discharge amount individually set, and the solidified material slurry is discharged. The slurry (solidified material liquid) is uniformly and reliably dispersed over the entire cross section of the excavated soil, and is agitated and mixed to obtain a uniform improved soil column throughout. Although the above description has been made on the deep ground improvement method, it goes without saying that the present invention is not limited to this and can be applied to other ground improvement methods. As described above, according to the present invention, the excavated soil is added to the excavated soil using the excavating agitating device having the excavating blade and the agitating blade at the tip of the excavating shaft while mixing and stirring. In the method for constructing an improved earth column, a discharge port is provided at a lower portion and an upper portion at a tip portion of a drilling shaft, and the lower discharge port is provided with a discharge port provided at a side portion at a tip portion of the drilling shaft, a cutting blade or a stirring blade. And a discharge port provided at a radially intermediate portion of the excavator, the discharge port at the radially intermediate portion is oriented in a direction perpendicular to the blade extending direction in plan view, and further, the upper discharge port is formed by a drilling shaft. And a discharge port provided at a radially intermediate portion of the stirring blade, and the discharge port at the radially intermediate portion is in a direction perpendicular to the blade extending direction in plan view. So that the lower discharge port A large-diameter excavating and stirring device is provided in which an independent solidified material liquid supply passage is connected to each of the outlet and the radially intermediate outlet and the side outlet of the upper outlet and the radially intermediate outlet. use of lower discharge port reaches a predetermined depth
In the plan view of the discharge port on the side of the excavation shaft and the middle part in the radial direction,
Solidified material liquid from the discharge port facing in the direction perpendicular to the existing direction.
Excavation and mixing and agitation are performed while jetting , and when it reaches the lowermost end, the supply of the solidifying material liquid from the lower discharge port is stopped, and the discharge port on the side of the excavation shaft of the upper discharge port and the radially intermediate portion are viewed in plan.
In order to carry out lifting and mixing while ejecting the solidified material liquid from the discharge port oriented at right angles to the blade extension direction, the solidified material liquid is applied to the inside and outside of the excavated soil during excavation stirring and ascent stirring. it is possible to supply the respective ejection amount can be arbitrarily set, beyond the example 1.5m
Drilling of solidified material liquid even for large-diameter improved soil columns
Uniformly over the entire cross section of excavated soil excavated with wings ,
And can be reliably spread over
It is possible to easily build a uniform large-diameter improved soil column over the entire cross section of the excavated soil .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view showing one embodiment of a distal end portion of a large-diameter excavating and stirring apparatus used in the construction method of the present invention. FIG. 2 is a cross-sectional view of FIG. [Description of Signs] 1 ... Drilling shaft 2 ... Drilling bit 3 ... Drilling blade 4 ... Anti-rotating blade 5 ... Stirring blade 10 ... Drilling shaft discharge port 10 for lower discharge port "... Drilling shaft discharge port for upper discharge port 11 ... Excavation blade discharge port 11 "for lower discharge port Drilling blade discharge port 12 for upper discharge port ... Horizontal supply pipe 12" ... Horizontal supply pipe 13 ... Solidified material slurry for excavation shaft discharge port for lower discharge port (Solidified material liquid) supply passage 13 ″ solidified material slurry for the excavation shaft discharge port for the upper discharge port (solidified material liquid) supply passage 14 solidified material slurry for the excavation blade discharge port for the lower discharge port (solidified material) Liquid) supply passage 14 "... solidified material slurry (solidified material liquid) supply passage for the excavating blade discharge port for the upper discharge port

Claims (1)

(57) [Claims 1] An improved soil by mixing and stirring while adding a solidifying material liquid to an excavated soil using an excavating and stirring device having an excavating blade and a stirring blade at a tip portion of an excavating shaft. In the method of constructing a pillar, a discharge port is provided at a lower portion and an upper portion at a tip portion of a drilling shaft, and the lower discharge port is provided with a discharge port provided at a side portion at a tip portion of the drilling shaft, and a radius of a drilling blade or a stirring blade. A discharge port provided in the middle part in the direction, the discharge port in the middle part in the radial direction is oriented in a direction perpendicular to the blade extending direction in a plan view, and further the upper discharge port is formed on the side surface of the excavation shaft. And a discharge port provided at a radially intermediate portion of the stirring blade, and the discharge port at the radially intermediate portion faces in a direction perpendicular to the blade extending direction in plan view. And radially intermediate the outlets on the side of these lower outlets Using a large-diameter excavation and stirring device that connects an independent solidification material liquid supply passage to each of the discharge port of the part and the discharge port of the side part of the upper discharge port and the discharge port of the middle part in the radial direction, When the depth is reached, the discharge port on the side of the excavation shaft at the lower discharge port
And at right angles to the blade extension direction
Excavation and mixing and stirring are performed while ejecting the solidified material liquid from the discharge port facing in the direction, and when the solidified material liquid is reached to the lowermost end, the supply of the solidified material liquid from the lower discharge port is stopped, and the excavation shaft side portion of the upper discharge port is
Discharge port and radially intermediate portion
By performing the pulling-mixed stirred while ejecting the solidified material liquid from the discharge port facing the perpendicular direction, of drilling at drilling blades
The solidified liquid uniformly over the entire cross section of the excavated soil,
Of the excavated soil excavated by the excavator
A method for constructing a large-diameter improved soil column, comprising: building a large-diameter improved pillar uniformly over the entire cross section .