JP2012219569A - Method and device for creating ground hardening layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problems in using a spiral screw blade as a mixed agitating blade of an injection rod that: because the outer peripheral surface of a rod body and a screw blade surface are in close contact with each other between which there is no gap space, this restricts the fluidity of excavation earth due to agitation, increasing the rotational torque; and that the pull-up speed and rotational speed of agitating blade are forced to be kept constant, making it difficult to perform injection adjustment.SOLUTION: Lower stage agitating blades 12A and 12B intersecting upper stage agitating blades 11A and 11B in a cross shape are set at prescribed intervals at the lower part of the upper stage agitating blades projecting to right and left, and belt-like rotation blades 2A and 2B are connected from the tip of upper stage agitating blade 11A to the tip of lower stage agitating blade 12A and from the tip of upper stage agitating blade 11B to the tip of lower stage agitating blade 12B respectively to constitute an agitating blade body.

Description

  In the present invention, an upper stirring blade extending left and right and a stirring blade extending in a direction intersecting with the upper stirring blade and a cross at a predetermined interval are provided in two stages, and located at 270 degrees downward from the tip of the upper stirring blade. A swirling swirl that swirls and descends to the tip of the corresponding lower stirrer blade and joins to the tip of the lower stirrer blade, and swivels to the tip of the corresponding lower stirrer blade located 270 degrees below the tip of the other upper stirrer blade A stir-injection rod in which a belt-like swirling blade that descends and is joined to the tip is set, and a horizontal injection nozzle is set at the upper part of the lower base of the lower stirring blade and the lower part of the lower base of the lower stirring blade. In addition, the hardened material is pumped and sprayed at a high pressure from each nozzle, while the stirring injection rod is rotated and lowered and raised to the target ground to create a ground hardened layer construction method in the ground. It relates to the apparatus.

  Conventionally, for foundation support and reinforcement support for soft ground, there have been many ground hardening material injection methods for stirring and excavating the target ground by rotating the ground hardening material injection rod while jetting the ground hardening material at high pressure. However, depending on the construction environment and the softness of the ground, there is a problem that the efficiency is poor and the stirring force is insufficient.

  Correspondingly, direct stirring by a stirring blade is performed, and in order to increase the diameter of the hardened material injection layer, as shown in Patent Document 1, for example, an injection nozzle is provided at the tip of the stirring blade. In some cases, an injection nozzle is set on the agitating blade, such as injecting a curing material in the horizontal direction.

  However, since the conventional curing material injection is mainly in the horizontal direction, there is a problem in the adjustment of the direct stirring by the stirring blade and the fluid stirring by the curing material jet, the curing material does not spread sufficiently in the stirring area, Uneven mixing of the soil and the hardener is likely to occur, and a further problem remains in the reliable and uniform stirring and mixing of the soil.

  In order to reduce the burden of rotational torque and make the operation of the rod smooth in order to cope with the problem of ground pressure applied to rotational torque due to such uneven mixing and deep drilling, for example, as shown in Patent Document 2 In addition, the upper and lower blade tips constituted by the spiral spacing of the spiral blades may be connected at predetermined intervals by swirl blade struts that direct the swirl in a direction opposite to the swirl direction of the screw, to constitute a rod. Has been done.

In addition, if the lifting speed and rotation speed of the stirring blade are set to be constant, the lifting and rotating screw blade cannot discharge the amount of earth and sand commensurate with the supply amount of the solidifying slurry, and the soil caused by excess soil removal. In order to prevent a decrease in pressure or an increase in earth pressure due to lack of soil discharge, as shown in Patent Document 3, a screw rod having a spiral screw blade, a drilling stirring blade, and a solidifying material discharge port It has also been proposed to use a ground improvement device provided with a solidifying material supply means comprising
JP 50-107714 A Japanese Patent No. 3453351 Japanese Patent No. 3527574

  When stirring directly with a stirring blade, an increase in rotational torque generated by the resistance of the ground applied to the rotation of the injection rod is a problem, which greatly affects work efficiency. In addition, since the earth is discharged only by the outer peripheral surface of the rod body and the stirring blade that performs the stirring action, there is no room for adjustment of the earth removal, and the volume ratio is only about 60 to 70% with respect to the total amount of the hardener. There is a problem that the ground pressure may be lost and the ground pressure may be lost due to the earth not being discharged to the surface.

  On the other hand, in the case of the prior art using the screw blade, since the spiral screw blade is used as a stirring blade and a propulsion blade as it is, there is no void space between the outer peripheral surface of the rod body and the blade surface that performs the stirring action, and mixing is performed. Since the stirring operation is performed in close contact with the outer peripheral surface of the rod, there is a problem in that the fluidity of the excavated soil by stirring is restricted, and the lifting speed and rotation speed of the stirring blade must be constant.

  The present invention is intended to address the above-described problems, and is provided with a lower stirrer blade extending in a cross shape and the upper stirrer blade at a lower portion at a predetermined interval from the upper stirrer blade, and the tip of the upper one stirrer blade 270 degrees downward from the tip of the corresponding lower agitating blade and swirling down to join the tip of the lower agitating blade, and 270 degrees below the tip of the other upper agitating blade By setting a swirl swirl that swirls and lowers at the tip of the lower stirring blade that joins to the tip, a direct gap and a step gap are formed between the outer peripheral surface of the injection rod and the swirl swirl that connects the upper and lower stages. By creating, the fluid lift applied to the excavated soil by agitation is utilized through the gap and further contributes to the reduction of the injection rod rotational torque.

  In other words, the upper stirrer blade and the lower stirrer blade are divided into two stages at predetermined intervals, and the corresponding tip portions are connected by the belt-shaped swirl blades to maintain the propulsion function of the screw blades, thereby increasing the total injection amount of the hardener. On the other hand, soil removal up to 80 to 100% in volume ratio was enabled to maintain the balance of ground pressure and suppress ground displacement.

  Also, set the horizontal injection nozzles at the upper part of the lower base stirring blade attachment base and the lower lower stirring blade lower attachment base of the stirring injection rod, respectively, and pump the hardener to inject high pressure from each nozzle. In this way, the hardened material was injected into the target ground, and the lift force was promoted by directing the swirling fluidity given to the excavated earth and sand by the swirling blades by the injection force of the hardened material jet.

  Furthermore, in order to enhance the swirl fluidity and mixing effect of the excavated sediment due to the rotation of the rod, each stirring blade paired in the upper and lower stages corresponds to each with a twist angle inclined in the opposite direction with respect to the rod. The horizontal injection nozzle set in the upper part of the lower base blade mounting base is injected in the downward direction, and the horizontal injection nozzle set in the lower part of the base is injected in the upward direction. did.

  By injecting the hardened material horizontally from the mounting base of the lower stirrer blade along the stirrer blade, the directions of the digging jet flow are mixed to prevent co-rotation in the viscous ground, and the ground crushing force and the hardened material Since the reach of the jet is also extended, it is possible to construct large-diameter ground improvements that were previously impossible with small machines.

  By configuring the present invention as described above, a gap and a step gap are directly created between the outer peripheral surface of the injection rod and the swirl swirl blade connecting the upper stage and the lower stage. The wing surface that was in close contact with the surface of the slab is eliminated to create a void, and the swirl fluidity of the excavated soil provided by the swirl propulsion force through this space allows the free pressure along the rod outer peripheral surface to be released to release the ground pressure. Got.

  In addition, the restriction that the lifting speed and rotation speed of the stirring blade, which could not be avoided in the case of screw blades, must be constant can be removed by the creation of the above-mentioned gap. It is possible to adjust the injection amount of the hardened material according to the rotation speed, and avoiding ground displacement based on the effect of adjusting the rotation speed according to the ground pressure of the target ground and creating a balanced ground hardened layer The above-described effects such as reduction of rotational torque can be obtained.

The embodiment of the present invention shows an upper stirring blade, a lower stirring blade, and a swirling blade connected to each corresponding tip, and a stirring injection rod tip monitor portion showing a setting state of a base injection nozzle of the lower stirring blade. Enlarged perspective view Similarly, an enlarged vertical cross-sectional side view of the stirring injection rod tip monitoring portion showing the state of the hardened material flow passage in the rod, with the stirring injection rod tip monitoring portion of FIG. 1 taken as a longitudinal section along the rod axis. Similarly, a construction diagram with the target ground as a longitudinal section showing the fluidity of the excavated soil in the state where the stirring rod is rotated and lowered into the target ground. Similarly, the perspective view of the whole apparatus showing the construction state flaw that inserts the stirring injection rod into the target ground and creates a ground hardened layer

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Reference numeral 1 denotes a stirring injection rod. Upper stirring blades 11A and 11B are set to protrude from the left and right on the tip monitoring unit M, and the lower stirring blades 12A and 12B are formed in a cross shape with the upper stirring blade with an interval of about 300 mm below. Set to intersect.

  Upper stirrer blades 11A and 11B are set with a twist angle inclined in opposite directions with respect to the rod, and lower stirrer blades set at a portion of 270 degrees below and spaced from the tip of 11A. The base end of the swirl swirl blade 2A to be joined to the tip of 12A is joined, and the tip of the upper stirring blade 11B is joined to the tip of the lower stirring blade 12B set at a position of 270 degrees below the same distance as described above. The base end of the belt-like swirl vane 2B is joined.

  The lower stirring blades 12A and 12B are planted with a torsional inclination with respect to the rod 1 at an interval of about 300 mm from the upper stirring blade 11 and equipped with a cutter bit 3 on one side of the lower surface side. The horizontal injection nozzle 31a is set in the lower direction toward the blade surface of the lower stirring blade 12A, and the horizontal injection nozzle 31b is formed in the lower portion of the mounting base of the lower stirring blade 12B. It is set in the upward direction toward the blade surface of 12B.

  The stirring injection rod 1 includes an upper stage stirring blade 11 and a lower stage stirring blade 12 configured as described above at the tip part, and the belt-like swirl blades 2 communicate with the upper and lower stages between the tip parts of the corresponding blade bodies, A screw structure is formed entirely through a swirl space 21 that forms a gap, and a rod that can be extended and joined by a claw joint 13 with a monitor M having an excavating blade 14 at the tip is mounted.

  The rear end is connected to a curing material supply hose 41 connected to the curing material plant via a swivel 15, and receives the slurry-like curing material prepared and supplied in the curing material plant through this, and the lower stage is provided by the curing material pumping flow path 4. The stirring blades 12A are pumped to the horizontal injection nozzle 31a at the upper part of the attachment base and the horizontal injection nozzle 31b at the lower part of the 12B attachment base, and are injected into the target ground from each nozzle.

  Reference numeral 16 denotes a spindle leader that leads the raising / lowering drive of the stirring injection rod 1 and is supported by the mother machine installed on the construction ground, the leader machine 17, and the stirring injection rod 1 is rotatably held to drive the raising / lowering drive. It takes the lead as a main shaft and gives the rod 1 rotational drive by the rotational drive mechanism 18.

  If the stirring injection rod 1 configured as described above is lowered into the target ground while being rotationally driven in the forward rotation direction of a screw structure composed of upper and lower stirring blades and a belt-like swirling blade connected to each tip. The excavated soil excavated in a swirling manner by the cutter bit 3 on the lower surface of the lower stirring blades 12A and 12B is given an upward conveying force by the swirling swirl blade, while the earth and sand in the swirling space 21 descends the rod outer peripheral surface. Because of this, the entire excavated soil is given random fluidity.

  Further, if the hardener is pumped from the hardener plant to the stirring injection rod 1, the hardener is injected from the horizontal injection nozzles 31 a and 31 b set at the mounting base of the lower stirrer blade 12 through the pumping flow path 4. The nozzle 31a is aimed at the tip of the blade from the upper part of the mounting base of the stirring blade 12A, and repels viscous soil and the like that sticks to the blade surface as the jet is struck obliquely along the upper surface of the stirring blade. At the same time, the flight distance is extended by being guided to the wing surface.

  The excavated soil imparted with random fluidity in this manner is not forced to be conveyed upward like the screw auger due to the presence of the swirling space 21, and therefore the ground pressure density due to the injection of the hardener is the ground pressure of the target ground. It is possible to adjust by changing the rotational speed of the stirring injection rod 1 corresponding to the internal pressure.

  The descent of the agitating and pouring rod 1 to the target ground keeps a balance between the ground pressure by the discharge amount by the hardening material injection from the injection nozzles 31a and 31b and the soil discharge by the lift due to the random fluidity of the excavated soil as described above. When the predetermined depth is reached, the stirring and injection rod 1 is moved forward while the hardener is being injected or the hardener is not sprayed depending on the state of the target ground and the state of the hardened ground layer. It is determined whether to lift and extract while rotating, or to perform the injection of the curing material or to lift and extract the stirring injection rod 1 without rotating.

  That is, when the stirring / injecting rod 1 is lifted and removed while rotating forward, the swirl swirl blade 2 acts as a propulsive force in the downward direction, but acts on the excavated soil in the direction of pushing up and discharging the excavated soil. The belt-shaped swirling blades 2 act as a driving force in the upward direction when excavating the excavated soil. Since the excavated soil is arranged downward and is pulled out by the driving up of the leader machine 17, it is selected as a finishing method depending on the state of the target ground and the state of the ground hardened layer formed.

  In the first embodiment, the stirring injection rod 1 is inserted into the target ground while being rotated forward along the swirling direction of the swirl swirl blades, and is lifted and removed while rotating in the normal direction. The cement milk is rotated at 40 to 50 rpm while being injected at a discharge rate of 100 liters / min as a hardener at a jet pressure of 5 to 15 Mpa from the lower stirring blade base nozzle at the time of lowering the insertion into the target ground.

  In this case, the excavated sediment is pushed up in the ground surface direction by the swirling swirl blade 2, while a hardened material in which cement milk is injected at a discharge rate of 100 liters / min as a hardener from the lower stirring blade base nozzle with an injection pressure of 5 to 15 Mpa. Although the ground is injected, unlike the conventional screw blades, the presence of the swirl space 21 suppresses the earth to be discharged to the ground surface. Therefore, by adjusting the rotation speed of the stirring injection rod 1, it is substantially the same as the hardened material to be injected. A large amount of earth and sand is discharged to the surface of the earth and the balance of ground pressure is maintained.

  When the ground pressure balance is maintained at the bottom dead center of the stirring injection rod 1 as described above, the stirring injection rod 1 is rotated forward so that the upward removal of the stirring injection rod 1 suppresses the influence on the surrounding ground. However, since the stirring soil is further pushed up and discharged, the rotational speed is suppressed to about 10 to 30 rpm, and the hardened material having the injection pressure from the lower stirring blade nozzles 31 a and 31 b of 5 to 15 Mpa. The soil was compensated for by jetting.

  Due to the presence of the swirl space 21, the rotational torque at the time of lowering of the rod while jetting the hardener from the lower stirring blade base nozzle is reduced, and rotation at 40-50 rpm is possible. By rotating at 10-30 rpm while injecting at a discharge rate of 100 liters / min, the balance of the ground pressure was kept constant, and it was possible to create without causing ground displacement.

  In the case of the conventional example, the reference diameter layer of φ1000 is rotated at 30 to 50 rpm while being injected at a cement milk injection pressure of 5 to 15 MPa and a discharge amount of 100 liters / min.

  In Example 2, when the stirring injection rod 1 was lowered and inserted, the hardened material was not injected from the lower stirring blade nozzles 31a and 31b. By the way, while rotating the curing material from the lower stirring blade nozzles 31a and 31b at an injection pressure of 10 to 20 Mpa and a discharge amount of 150 liters / min, the rotation is increased at 40 to 50 rpm.

  In this method, when the rod 1 is lowered and inserted, the excavated soil is pushed up by the belt-like swirl vanes 2 and the soil agitated by the push-down through the swirling space 21 by the pressure contact of the descending rod outer peripheral surface is relatively low. Even if the injection pressure is applied, a hardened material with a high discharge amount can be handled, and by adjusting the rod rotation speed, the earth lifting force can balance the ground pressure and the ground displacement can be kept low.

  According to the method of the second embodiment, the ground having a high N value is targeted. According to this, the rotational torque is reduced by the swivel space 21, and therefore the hardening material can not be injected when the stirring injection rod 1 is inserted and lowered. Time and labor for material saving and construction can be greatly reduced.

  In the third embodiment, when the agitating / injecting rod 1 is lifted and removed, the rod is reversed and lifted, and the depressing action of the excavated soil by the upward propulsion by the belt-like swirl blades 2 suppresses the earth and sand in the hardened layer W formation part. Although consolidation is strengthened, it corresponds to the case where the soil is excessively dense or dense at the time of the rod descending insertion, or when the target ground is composed of alternate layers.

  The ground pressure of the target ground can be measured by using a measuring device, but as shown in FIG. 3, it is grasped by comparing the amount of soil discharged from the excavated soil into the rod insertion port and the amount of hardened material discharged. Therefore, while adjusting the rod rotation speed and switching between reverse rotation and forward rotation, the hardened layer has a larger diameter and the foundation for construction is created without breaking the balance of ground pressure.

  The ground hardened layer construction method and its apparatus according to the present invention are as follows. It is possible to create a homogeneous improved mixed layer with an extremely high degree of mixing of materials without breaking the balance of ground pressure, and actively utilizing land that could not be used due to soft geology by efficiently strengthening soft ground Can be used to push forward.

DESCRIPTION OF SYMBOLS 1 Stirring injection rod 11A Upper stirrer blade 11B Upper stirrer blade 12A Lower stirrer blade 12B Lower stirrer blade 13 Claw joint 14 Excavation blade 15 at the tip of the monitor part Swivel 16 Spindle leader 17 Leader machine 18 Rod rotational drive mechanism 2 Strip swirl blade 21 Rod Swivel space 3 between the blade and the swirling blade 3 Cutter bit 31a Horizontal injection nozzle 31b of the lower stirring blade 12A Horizontal injection nozzle 4 of the lower stirring blade 12B Hardening material feed channel 41 Hardening material supply hose G Target ground M Monitor the rod tip Part W Preparation hardened material layer

Claims (6)

  An upper stirrer blade extending to the left and right of the rod and a lower stirrer blade extending in a cross shape with a predetermined interval below the upper stirrer blade are provided, and located at 270 degrees below the tip of the upper one stirrer blade. A swirling swirl that swirls and descends to the tip of the corresponding lower stirrer blade and joins to the tip of the lower stirrer blade, and swivels to the tip of the corresponding lower stirrer blade located 270 degrees below the tip of the other upper stirrer blade A stir-injection rod in which a belt-like swirling blade that descends and is joined to the tip is set, and a horizontal injection nozzle is set at the upper part of the lower base of the lower stirring blade and the lower part of the lower base of the lower stirring blade. In addition, the hardened material is pumped and high-pressure jetted from each nozzle, and the stir-injection rod is rotated, and then the ground hardened layer is constructed while being lowered, raised, or both to the target ground.   While the hardened material is jetted from the lower stirrer blade base nozzle at a high pressure, the stirrer injection rod is rotated forward along the swirl direction of the swirl swirl blade and inserted downward into the target ground. The ground hardened layer construction method according to claim 1, wherein the same is rotated in the forward direction so that the hardened material is lifted and extracted from the lower stirring blade base nozzle while being injected at high pressure.   The stirring injection rod is rotated forward without lowering the curing material from the lower stirring blade base nozzle, and when the predetermined depth is reached, the stirring injection rod is rotated forward while the curing material is jetted from the lower stirring blade base nozzle at a high pressure. The ground hardened layer construction method according to claim 1, wherein the ground hardened layer is constructed so as to be lifted and removed.   The ground hardened layer construction method according to claim 1, wherein the stirring injection rod inserted at a predetermined depth of the target ground is configured to be lifted and removed by rotating in a reverse direction while high pressure jetting the hardener from the lower stirring blade base nozzle.   The operation of lowering the high-pressure injection rotation to the target ground of the stirring injection rod and increasing the high-pressure injection rotation is configured to adjust the rotation speed in accordance with the ground pressure of the target ground. The ground hardened layer construction method described   An upper stirrer blade extending to the left and right of the rod and a lower stirrer blade extending in a cross shape with a predetermined interval below the upper stirrer blade are provided, and located at 270 degrees below the tip of the upper one stirrer blade. A swirling swirl that swirls and descends to the tip of the corresponding lower stirrer blade and joins to the tip of the lower stirrer blade, and swivels to the tip of the corresponding lower stirrer blade located 270 degrees below the tip of the other upper stirrer blade A stir-injection rod in which a belt-like swirling blade that descends and is joined to the tip is set, and a horizontal injection nozzle is set at the upper part of the lower base of the lower stirring blade and the lower part of the lower base of the lower stirring blade. Hardened ground layer forming device, which is supported by rotating vertical drive mechanism

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