JPH0819670B2 - Ground improvement method and equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a ground improvement method and an apparatus.

(B) Conventional technology Conventionally, as a method for improving soft ground, a hardening material such as mortar is poured and stirred into excavated soil in an excavation hole drilled in the ground, and the ground strength is increased by hardening this kneaded material. There was a construction method called.

Also, in order to improve the soft ground, an excavation blade and a stirring blade are installed at the lower end of the rotary shaft, and in the excavation hole by the blade, excavated soil and a hardening agent such as mortar injected separately make it soft. There was a ground improvement device that improved the ground.

(C) Problems to be Solved by the Invention However, the ground that needs improvement is often a sedimentary layer in terms of geology, and such a sedimentary layer is a fine-grained silt layer or peat layer, or various soil types. In many cases, it is constructed in alternate layers, for example, when the ground is improved by using cement-based hardening material for the formation of alternating layers of fine-grained sand layer and fine-grained silt layer. Since the result of hardening in the part of the silt layer is extremely inferior to that in the part of the sand layer, sufficient ground strength cannot be obtained, and therefore there is a drawback that variations in the strength are generated. In order to eliminate this drawback, an excessive amount of hardener has been mixed, but this cannot reduce the sufficient ground strength and variation, and the peat layer is hard to cure. It was difficult to get the effect.

In addition, if mortar, which was prepared by mixing cement and sand with water in advance, is poured into this ground and stirred, the mortar has poor fluidity and dispersibility, so the mortar penetrates into the voids of the excavated soil structure and mixes. It takes a long time to complete, so the volume of the mixture in the middle of mixing and stirring increases, the mixture overflows to the ground surface and the consolidation effect decreases, and the effect of ground improvement is not sufficient, and this overflowed further. The excavated soil must be transported in order to dispose of it, resulting in extra work.
When the injection of mortar is stopped, there is a drawback that sand and cement are separated in the injection device, which hinders the subsequent work.

(D) Means for Solving the Problems In the present invention, in the excavated soil in the excavation hole drilled in the ground,
First, the ground powder is mixed and stirred, and then a hardening material is poured into the mixture of the above-mentioned excavated soil and the granulated powder and stirred, and the excavating blade body is provided at the lower end of the cylindrical rotary shaft. And a stirring blade are connected in series, and the cylindrical rotation shaft is constituted by an outer shaft and an inner shaft that rotate in mutually opposite directions, and moreover, granular powder can be accommodated between the outer shaft and the inner shaft. In addition to being configured, a granular powder quantitative discharge mechanism is arranged below the accommodated granular powder, and the granular powder quantitative discharge mechanism is a pocket that is connected to one of the inner and outer shafts for accommodating a certain amount of granular powder. And an openable / closable lid body for discharging the granular powder from the pocket, and an engagement pin for opening the lid, which is connected to the other of the inner and outer shafts and engages with the lid body by rotation of the inner and outer shafts in opposite directions. Providing a ground improvement device configured to stir and knead the granular powder discharged from the mechanism and the excavated soil by the excavating blade with the stirring blade. One in which cents to.

(E) Action / Effect According to the present invention, attention is paid to the fact that the granular powder simple substance has better fluidity and dispersibility than a mixture such as mortar,
By first mixing only the granular powder into the excavated soil in the excavation hole and stirring it, the soil quality is improved prior to the mixing and stirring of the hardened material, and the dispersion of the granular powder in the structure of the excavated soil, that is, mixing It is carried out quickly, and for this reason, the volume increase of the mixture during mixing and stirring is stopped to a slight extent, so that the overflow of the mixture to the ground surface is suppressed and the consolidation effect is sufficiently performed, and no soil disposal work is required. Becomes

As described above, by improving the soil quality before the hardening material is mixed, the kneading with the hardening material is performed uniformly, and the variation in the improvement result is eliminated.

Further, since the granular powder quantitative discharge mechanism of the device of the present invention can control the discharge speed by the rotation speed of the rotary shaft, the amount of granular powder suitable for the soil quality of the formation at the depth where the mechanism is located. It is possible to discharge the body and mix and knead the optimum amount of granular powder for each layer, not only for a single layer of silty material but also for the ground where the sand layer and the silt layer cross each other, for example. As a result, the soil quality can be improved to enhance the effect after hardening, and the ground strength after hardening can be increased. In addition, the curing material can be effectively acted on the peat layer by mixing the granular powder.

As described above, according to the soil properties of the formation, by mixing and kneading an appropriate amount of granular powder for each, the factor relating to the ground strength after hardening of each layer is increased and homogenized, and the ground improvement work results and This has the effect of improving reliability.

(F) Embodiments An embodiment of the present invention will be described in detail with reference to the drawings.
Indicates a ground improvement device, and the device (A) is composed of a movable base machine (1) and a hardening material supply device (2). The base machine (1) is rotated by a leader (3) by a rotary shaft (4). ) Is vertically supported, and the excavating blade (6) is connected to the rotary shaft (4) and the lower end of the coaxial shaft (4) by a motor (5) interposed between the leader (3) and the rotary shaft (4). ) And the stirring blade (7) are rotated while the coaxial (4) is lowered along the leader (3) to form a drill hole (H) perpendicular to the ground (G).

The rotating shaft (4) is composed of a double shaft, that is, a hollow tubular outer shaft (9) and an inner shaft (10) inserted through the outer shaft (9). The inner and outer shafts (10) and (9) are configured to rotate in opposite directions by a counter rotating gear mechanism (11) provided between the upper end and the motor (5). Extends further downward than the outer shaft (9), and at the lower end of the inner shaft (10) the excavating blade (6)
Are lined up.

A stirring blade (7) is arranged above the excavating blade body (6), and the stirring blade (7) is a large / medium / small stirring blade body (7a) (7).
b) (7c), each wing body (7a) (7b) (7
c) is formed in a substantially trapezoidal frame shape when viewed from the side surface, and a predetermined number of them are arranged radially around the rotation axis (4).

The small stirring blade body (7c) has upper and lower ends fixed to the lower end of the outer shaft (9), and the middle stirring blade body (7b) is smaller than the small stirring blade body (7c). It is formed in a large trapezoidal frame shape,
The small stirring blade body (7c) is arranged so as to surround the outside, the lower end of the middle stirring blade body (7b) is fixed to the lower end of the inner shaft (10), and the upper end is the small stirring blade body (7c). ) Above the fixed position of the upper end, it is axially supported by the outer shaft (9), the large stirring blade (7a) surrounds the outside of the middle stirring blade (7b), and its upper end is located on the outer shaft (9). ), And the lower end is pivotally supported by the inner shaft (10).

Therefore, the medium stirring blades (7b) are large and small stirring blades (7a) (7
In the middle of c), they will rotate in the opposite direction.

The lower end of the hollow tubular outer shaft (9) is located below the lower end of the small stirring blade (7c), and a substantially conical closing plate (12) is connected to the lower end of the outer shaft (9). A discharge hole (13) for the granular powder (8) described later is provided in (12).

Further, a granular powder quantitative discharge mechanism (B) described below is provided at the lower end of the rotary shaft (4).

That is, a hopper (14) communicating with the inside of the hollow tubular outer shaft (9) is provided at the upper end of the outer shaft (9),
A screw (15) is continuously provided on the outer peripheral surface of the inner shaft (10) below the hopper (14) and is surrounded by a transfer inner cylinder (16) having a smaller diameter than the outer shaft (9). The upper edge of (16) is connected to the inner peripheral surface of the outer shaft (9) through a substantially funnel-shaped shaping cylinder (17),
The lower end is opened downward, and the opening edge is obliquely cut.

Therefore, the granular powder (8) falling and deposited on the measuring mechanism (18) described later does not rise above the upper end of the oblique cutout opening end of the lower end of the inner transfer cylinder (16) due to the self-regulating action.

Further, a measuring mechanism (18) is arranged below the inner conveying cylinder (16), and the measuring mechanism (18) includes an inner peripheral surface of the outer shaft (9) and an outer peripheral surface of the inner shaft (10). Upper and lower discs (18
A measuring vessel (18c) is hung vertically on the upper disc (18a) between a) and (18b), and the granular powder (8) in the measuring vessel (18c) is transferred to the outer shaft (9).
When the measuring basin (18c) coincides with the hole (18d) formed in the lower disc (18b) by rotating on the circumference by rotating, the granular powder (8) inside the measuring basin (18c) By making it fall downward, a certain amount of granular powder (8) is made to fall downward for each relative rotation of the inner shaft (10) and the outer shaft (9).

In addition, since the granular powder (8) has a constant density due to the self-adjusting action described above, accurate weighing is performed.

A pocket (19) is vertically provided on the lower disc (18b) below the weighing mechanism (18), and the pocket (19) is gradually narrowed at its lower portion as shown in FIGS. 2 and 3. The upper open end of the pocket (19) matches the hole (18d) of the lower disc (18b), and the lower open end of the pocket (19) is covered with a lid (19a) that can be opened and closed. It is blocked.

That is, the lid (19a) is attached to the left and right flat support plates (19a).
b) and a plate-like lid portion (19c) that is curved in a substantially arc shape in a side view.
With, it is configured in a substantially U shape when viewed from the front, and the left and right support plates (19b)
The upper end of the pocket is pivotally attached (19d) to the left and right side plates of the pocket (19), and the lid (19c) is pivoted back and forth to move the pocket (1
The lower open end of 9) is opened and closed.

The lower opening end and the lid portion (19c) are formed so that the sliding contact surfaces of them are located on a virtual cylindrical surface with the pivotal attachment portion (19d) as the central axis.

Further, an engaging claw (19e) is rotatably and pivotally attached to a support plate (19b) on the inner shaft (10) side of the lid (19a) via a pin (19f). The lower end of 19e) is made to hang below the lid (19c), and the long hole (19g) formed in the claw (19e) is inserted into the stopper pin (19h) protruding from the side plate of the pocket (19). Regulates the drooping position.

On the other hand, an engaging pin (19j) is provided at a position corresponding to the engaging claw (19e) on the outer peripheral surface of the inner shaft (10) to project the inner and outer shafts (10).
The relative rotation of (9) causes the same pin (19j) to engage the pawl (19e).
The lid (19a) is opened via the pawl (19e) by abutting against the lid, and the lid (19j) and the pawl (19e) are unlocked when the lid (19a) is released. 19a) is a spring (19k) provided between the lid (19a) and the side plate of the pocket (19).
The lid is closed by the bias of.

By the opening, the granular powder (8) in the pocket (19) falls into the discharge hole (13) of the closing plate (12) and is closed by the fluid ejected from the nozzle (13a) provided on the inner shaft (10). It is extruded to the outside of the plate (12) and mixed into the excavated soil by the stirring blade (7). In the figure, (12a) is the closing plate (12) and the lower disc (18).
b) A shutter that can be freely opened and closed to prevent the intrusion of earth and sand into the space between them, and (12b) is an earth discharge plate that forms an operating space of the shutter (12a).

When the inner and outer shafts (10) and (9) are rotated relative to each other in the opposite direction to the above, the engagement pin (19j) slides on the lower end of the engagement claw (19e), and the claw (19e) moves upward. The lid body (19a) is lifted and the engaging action is not performed, and the lid body (19a) maintains the closed state.

Then, the granular powder discharged from the discharge hole (13) at the lower end of the outer shaft (9) is mixed with the soil in the excavation hole (H) by the large and medium stirring blades (7a) (7b) (7c). To be done.

In the figure, (20) shows a hose for injecting a liquid hardening material, and the hose (20) is a hardening material supply device (2).
The hose (20) is connected to a pump for hardening material, and through the swivel (20a) at the tip of the hose (20), it passes through the inner shaft (10) and the liquid hardening material is discharged from the nozzle (20b) at the lower end of the coaxial (10). It is to be ejected into the soil.

The embodiment of the present invention is configured as described above, and at the time of ground improvement work, first, by operating the motor (5), the excavating blade body (6) is rotated and lowered through the rotary shaft (4), The excavation hole (H) having a substantially cylindrical shape is bored in the ground, but the excavated soil is not discharged at this time, and the excavation blade body (6) and the stirring blade (7) are buried in the excavated soil. State.

During the above-mentioned excavation work, the granular powder (8) supplied to the hopper (14) is appropriately excavated from the granular powder quantitative discharge mechanism (B) in accordance with the soil quality of the formation where the stirring blade (7) is located. It is discharged into the inside and kneaded with the excavated soil by the stirring blade (7).

Then, when the excavating blade (6) reaches a predetermined depth, the descent of the blade (6) is stopped, the hardening material is injected into the kneaded material by the hardening material supply device (2), and the stirring blade is also used. While kneading in (7), the rotating shaft (4) is raised. In this example, the injection and kneading of the hardening material was repeated once more to improve the uniformity of the improved ground.

The ground improvement portion is effective after the curing period of the kneaded material of the hardened material, the excavated soil and the granular powder (8) has passed, and is continuously lapped during the curing period. By performing a lot of ground improvement work on the ground, it is possible to perform a continuous ground improvement work on the ground, and by constructing the ground continuously in a row, a continuous underground wall for stopping and stopping the soil in the ground. You can also build a body.

Especially for the ground that needs improvement, after the excavation of the drilling hole (H) and prior to the injection of the hardening material, the granular powder quantitative discharge mechanism of the present invention injects an optimum amount of the granular powder into each layer and kneads the mixture. By doing so, the sand or the like becomes an aggregate of the hardened ground and bears the pressure, so that strong ground improvement can be performed. In addition to sand, it is also possible to use granular foam such as granular furnace slag or pearlite as the granular powder used in the present invention.

According to the device of the present invention, it is possible to mix and stir only the granular powder in the formation, and stir and mix only the hardening material.
It is also possible to do both at the same time, and since a powdery hardener instead of granular powder can be injected into the soil, a ground improvement device for slurry hardener and a powdery hardener for powdery hardener The device of the present invention can be used as both of the above-mentioned devices, and conventionally, only one device of the present invention requires two kinds of devices.

Furthermore, by combining with steel materials etc. for ground improvement with the device of the present invention, it is possible to construct a support pile for a building using the local soil, and there is no need to dispose of soil. There is no need to transport soil and waste, and part of the bottleneck for construction will be eliminated.

Also, by providing a shutter at the discharge port of the granular powder into the soil, even if the discharge of the granular powder is stopped, the excavated soil is prevented from flowing back into the device. When using a solidified material to improve the ground at the bottom of the water, in the conventional equipment, in order to prevent water or mud from entering the equipment, pressure is applied to the equipment when removing the equipment from the ground at the bottom of the groove. However, there is a drawback that the head of the ground improved in breakage is destroyed by the fluid ejected at the above pressure when the device is removed, but in the device of the present invention, there is no need to apply pressure. Since invasion of water and mud is prevented, there is an advantage that the head of the same head is not destroyed by jetting of fluid and the ground floor is reliably improved.

As described above, according to the present invention, the strength of the improved ground is enhanced, and the applicable range of the ground improvement is applied to a super soft ground such as a silt layer having a particularly high water content, or a peat layer having a particularly high porosity. This has the effect of expanding the range.

[Brief description of drawings]

 FIG. 1 is an overall side view of a ground improvement device according to the present invention. FIG. 2 is a vertical cross-sectional view showing the main part of the present invention. FIG. 3 is a side view of the pocket. (A): Ground improvement device (B): Granular powder quantitative discharge mechanism (4): Rotating shaft (6): Excavator blade (7): Stirring blade (8): Granular powder

Claims (2)

[Claims] 1. A granular powder (8) is first mixed and stirred into excavated soil in an excavated hole (H) formed in a ground (G), and then a mixture of the excavated soil and granular powder (8). A ground improvement method characterized by injecting a stiffening agent into and stirring. 2. A cylindrical rotary shaft (4) in which a drill blade (6) and a stirring blade (7) are connected to the lower end of the cylindrical rotary shaft (4).
The outer shaft (9) and the inner shaft (10) that rotate in opposite directions.
In addition, the granular powder (8) can be housed between the outer shaft (9) and the inner shaft (10), and the granular powder is provided below the housed granular powder (8). A fixed amount discharge mechanism (B) is provided, and the fixed amount discharge mechanism (B) of the granular powder is the inner and outer shafts (10) (9).
A pocket (19) connected to one side for accommodating a certain amount of granular powder, an openable / closable lid (19a) for discharging the granular powder from the pocket (19), and an inner and outer shaft (10) (9) is connected to the other side and is constituted by an engagement pin (19j) for opening the lid that engages with the lid body (19a) by rotation of the inner and outer shafts (10) and (9) in opposite directions. A ground improvement device configured to stir and knead the granular powder (8) discharged from (B) and the excavated soil by the excavating blade (6) with a stirring blade (7).