JP2005273137A - Ground improvement method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ground improvement method capable of providing the ground having predetermined strength, by supplying and uniformly dispersing a predetermined quantity of a solidifying material. <P>SOLUTION: This ground improvement method includes a process of constructing a structure 2 and an underground wall 1 for surrounding the periphery of the ground 3a for supporting the structure 2 by mixing soil and the solidifying material by supplying the solidifying material to the soil around the structure 2, a process of drilling a hole 4 extending up to the ground 3a for supporting the structure 2 by penetrating through the underground wall 1, and a process of injecting chemicals by mixing compressed air from a chemical injection pipe 6 inserted into the hole 4. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a ground improvement method for preventing liquefaction of the ground, and in particular, the ground in a place where liquefaction damage due to a large earthquake is assumed, such as the foundation of an oil storage tank installed along the coast. It is related with the method of improving.

  Generally, the ground where liquefaction is assumed has many loose sand layers, and the N value is 30 or less. Here, liquefaction means that sand is pushed up by strong water due to an earthquake or the like, and the supporting force is lost, resulting in a state close to liquid. The N value means the number of hits required to allow the sampler to penetrate 0.3 m into the ground. In general, the N value can be obtained by a standard penetration test (JIS A 1219-1995) performed by the following procedure.

  First, a sampler (steel pipe that can be divided in two vertically) with an inner diameter of 0.035 m and an outer diameter of 0.0.51 m is set up at the bottom of a borehole that is vertically drilled in the ground. Second, a 63.5 kg cylindrical hammer is freely dropped from a height of 0.75 m onto a knocking head fixed to a rod (steel round bar) attached on the sampler. Third, record the number of strikes required to allow the sampler to penetrate 0.3 m into the ground as an N value. Fourth, collect a soil sample from the sampler. This sample can measure particle size distribution, soil particle specific gravity and clay water content. Fifth, drill the borehole and measure the N value every 1 m.

  The N value is widely used as an index of soil strength or firmness, but the same value varies depending on soil depth and soil type (for example, sand, clay). For example, sand with an N value of 10 at a depth of 10 m is loose sand that may be liquefied during an earthquake, but clay with an N value of 10 is stable soil and supports low-rise buildings. Has sufficient strength.

  In the ground where the damage of liquefaction is assumed, liquefaction does not occur if the N value can be increased to 30 or more. Conventionally, a ground improvement method for preventing liquefaction by a method of boring the ground and injecting grout has been adopted. In order to improve the ground where the oil storage tank etc. are installed, for example, drilling obliquely with respect to the ground surface, through the drilling rod used for boring, or inserting another injection pipe, A method of supplying grout (solidifying material such as cement) through an injection pipe is employed. In addition, a method is employed in which a periphery of the oil storage tank is excavated, a boring base is formed at the excavated location, and the grout is supplied from the boring base using the rod or the injection pipe. In these methods, although the ground strength in the range where the grout is supplied can be increased and an N value of 30 or more at which liquefaction does not occur, it can be supplied almost uniformly to the entire ground where the oil storage tank is installed. However, it was difficult to obtain a stable ground.

  Many oil storage tanks are built along the coast for imports from overseas and for accident prevention. Inevitably, a lot of landfill is used, so the strength can be increased by sand compaction pile method during construction. However, in recent years, the scale of earthquakes assumed has increased, and if the ground strength is not increased, sufficient liquefaction prevention cannot be achieved.

  In view of the above-described problems, a method has been proposed that can uniformly supply grout to the ground in a predetermined range (see, for example, Non-Patent Document 1 and Non-Patent Document 2). The first method is to drill the ground floor directly from the adjacent location without stopping the use of facilities and existing structures, and grout multiple ground points in a skewer shape from one drilling line. It is a method of construction by pouring. This method uses a small gyro that measures the absolute direction, detects the rod position in the drilling hole with high accuracy, and monitors the rod tip data such as the bending amount of the tip rod and the gyro position in the driver's seat in real time. By drilling holes and injecting grout in a skewer shape from a plurality of points, the pore water in the ground is replaced with grout. In this method, since the rod position can be detected and operated with high accuracy, the grout can be uniformly supplied into the ground.

  The second method is a method for avoiding liquefaction by mixing a sand ground that is liable to be liquefied with a cement-based solidifying material and solidifying the ground itself. In this method, a shaft with blades (wings) is rotated to push the ground while stirring, and at the same time, a solidified material or slurry (solution containing the solidified material) is injected from a nozzle at the tip of the shaft, thereby allowing a diameter of 1 m. It is possible to build a solid ground pillar of uniform degree in the ground.

  The third method is a high-pressure jet agitation method in which the ground and the solidified material are efficiently mixed by the injection force of ultrahigh-pressure water. In this method, the solidifying material slurry is jetted from a nozzle at the tip of a rotating shaft at an ultrahigh pressure of 30 MPa or more, and mixed with the solidifying material at the same time while disturbing the ground by the jetting force. By this injection force, the solidified material can be spread over a range of about 2.5 m at the maximum, and a solid ground column with a maximum diameter of 5 m can be built in the ground.

  The fourth method is a method in which the second method and the third method are combined. The ground can be solidified while spraying the ultrahigh pressure slurry so as to cross from the tip of the blades arranged in two upper and lower stages.

  The fifth method is a chemical solution injection method in which liquefaction is prevented by injecting a chemical solution into the ground and replacing it with groundwater to give a stickiness to the entire ground. This construction method uses a special bit attached to the tip of the drilling pipe to advance while digging while rotating straight, stop rotating when turning, and advance while digging while turning in the direction in which the tip of the sleigh faces. A chemical solution is injected from the tip of the pipe, and a spherical improvement body having a diameter of 2 to 3 m is constructed at a time.

Although the above-mentioned method has characteristics such as no need for a shaft, there are restrictions such as the need for a dedicated machine and a dedicated chemical solution, and their use increases construction costs and can be easily constructed. There was a problem that construction could take a long time. Therefore, for example, a general-purpose chemical solution can be provided at a low cost, and a method that enables a chemical solution to be distributed widely and uniformly without performing drilling and chemical injection while detecting a rod position or the like. Is desired.
"Developed a curved hole drilling method for liquefaction countermeasures", [on line], January 22, 2004, Goyo Construction Co., Ltd., [Search February 21, 2004], Internet <URL: http: // www.penta-ocean.co.jp/news/d_news20040122.html> "Techno Library: Liquefaction Countermeasure Technology", [on line], September 2002, Kashima Construction Co., Ltd. [searched on February 21, 2004], Internet <http://www.kajima.co.jp/ news / digest / sep_2002 / techno / techno.htm>

  The present invention has been made to solve the above-mentioned problems, and can be applied at low cost without the need for a dedicated machine or a dedicated chemical solution, and can easily and widely spread the chemical solution. It is an object of the present invention to provide a method that makes it possible to obtain a ground having a predetermined strength.

  The present invention prevents the chemical solution from penetrating to the outside by constructing the underground wall, and reliably injects a predetermined amount of the chemical solution into the soil range (the range surrounded by the underground wall). In addition, by supplying the chemical liquid together with the compressed air, it is possible for the compressed air to widen the gap and inject more chemical liquid, and to raise the chemical liquid as the compressed air rises to the ground surface, It was made by finding that it can diffuse upwards. As a result, a sufficient amount of the chemical solution can be injected in a short time, can be evenly distributed over a predetermined soil range, and the number of holes drilled by boring can be reduced. The above object of the present invention is achieved by providing the ground improvement method of the present invention.

That is, according to the invention of claim 1 of the present invention, the solidification material is supplied to the soil around the structure, the soil and the solidification material are mixed, and the structure and the surrounding of the ground supporting the structure Building an underground wall that surrounds
Drilling a hole that extends through the underground wall to the ground supporting the structure;
There is provided a ground improvement method including a step of injecting a chemical liquid mixed with compressed air from a chemical injection pipe inserted into the hole.

  According to the second aspect of the present invention, the method further includes a step of excavating the soil adjacent to the underground wall and constructing a shaft, and the step of drilling penetrates the underground wall from the shaft. Thus, a ground improvement method for drilling the hole extending to the ground supporting the structure is provided.

According to the invention of claim 3 of the present invention, the step of constructing the underground wall comprises at least one cutting member disposed at a tip portion, a blade at a peripheral portion, and an edge of the blade. A step of excavating the soil by rotating and lowering a stirring member provided with a solidifying material injection tube by a supporting means that supports the stirring member to be rotatable and liftable; and
While rotating and raising the stirring member, a slurry containing the solidification material or a gas in which the solidification material is dispersed in compressed air or nitrogen is supplied from the at least one solidification material injection pipe toward the soil. Process,
Mixing the soil and the slurry or the gas by rotating the blades,
Repeating the excavating step, the supplying step, and the mixing step, and constructing the underground wall in which a columnar solidified body is continuous around the structure and the ground supporting the structure. A featured ground improvement method is provided.

  According to a fourth aspect of the present invention, in the excavating step, the stirring member is rotated in a predetermined direction to excavate to a predetermined depth of the soil, and the soil is stirred, supplied, and mixed. In the process, the agitation member is rotated in a direction opposite to the predetermined direction to be raised toward the ground surface, the slurry or the gas is supplied, and the soil is agitated. Is provided.

  According to the invention of claim 5 of the present invention, the agitating member is provided around a tip conduit provided with the cutting member at a tip portion, a hollow shaft connected to the tip conduit, and the shaft. A spiral blade, a plurality of projecting members disposed on the upper surface and the lower surface of the spiral blade, and an interior of the shaft body, penetrating the shaft body toward the edge of the spiral blade And the at least one solidifying material injection pipe for supplying the slurry or the gas, and the shaft body has a large diameter at a central portion along the length direction, and both end portions. The ground improvement method characterized by being formed so that a diameter may become small is provided.

  According to a sixth aspect of the present invention, the support means includes a traveling part for moving, a rod for connecting the stirring member, and a clamp for rotating the rod in both forward and reverse directions and supporting the rod. And the lifting and lowering means for lifting and lowering the rod, and the excavating step includes a step of rotating the rod by the clamping portion and lowering the rod by the lifting and lowering means, the supplying step, and the mixing step The step of performing provides the ground improvement method including the step of rotating the rod by the clamping part and raising the rod by the elevating means.

  According to the invention of claim 7 of the present invention, the chemical injection pipe is composed of a hollow pipe provided with a cutting member at a tip portion thereof and a plurality of connecting pipes connectable to the hollow pipe, and the step of drilling the hole. Then, the hole is drilled and the connecting pipe is connected, and in the step of injecting, the connected connecting pipe is removed each time the chemical solution is injected for a predetermined time. A ground improvement method is provided.

  According to claim 8 of the present invention, in the step of injecting, the chemical liquid is injected, and the compressed air is supplied in a direction opposite to the flow direction of the chemical liquid, whereby the injected chemical liquid is Provided is a ground improvement method characterized by mixing compressed air as bubbles.

  According to the ninth aspect of the present invention, two shafts are constructed so as to face each other through the structure, and an angle formed by two adjacent holes in each shaft is 5 ° to 10 °. There is provided a ground improvement method characterized in that a plurality of holes are drilled so as to have an angle of 0 °.

  According to invention of Claim 10 of this invention, the said hole is formed so that it may have a curved part, The ground improvement method characterized by the above-mentioned is provided.

  By providing the ground improvement method of the present invention, it is possible to supply a predetermined amount of a chemical solution and easily and uniformly disperse it, and to obtain a ground having a predetermined strength. Since the method of the present invention does not require a dedicated machine or a dedicated chemical solution, it can be constructed at low cost, and since it does not drill while checking the drilling direction with a dedicated machine, it can be performed in a short period of time. It can be constructed with. Further, in the method of the present invention, in order to construct the underground wall, the injected chemical liquid is prevented from penetrating outside the soil area surrounded by the underground wall, and the chemical liquid supplied in a predetermined amount is supplied to the underground wall. Can be reliably and uniformly infiltrated into the soil area surrounded by the above, and thereby, it is possible to construct at a lower cost without requiring additional chemical injection. Further, since the chemical liquid is supplied together with the compressed air, an additional chemical liquid can be injected in addition to the predetermined amount of the chemical liquid. In this case, higher ground strength can be obtained.

  The ground improvement method of the present invention comprises a dedicated machine suitable for the machine, including a sensor at the tip of the drilling line, a bent part in the middle of the line, and a means for arbitrarily bending the bent part, and a monitoring means. It is a method that makes it possible to spread a predetermined amount of a chemical solution to a soil area to be strengthened reliably and uniformly without using a chemical solution and to make the ground in the range to a predetermined strength easily and in a short time. . The ground improvement method of the present invention supplies a solidifying material to soil surrounding a structure such as an oil storage tank, mixes the soil and the solidifying material, and surrounds the ground around the structure and the ground supporting the structure. A step of drilling a hole extending through the underground wall to the ground supporting the structure, and a step of injecting a chemical solution mixed with compressed air from a chemical solution injection tube inserted into the hole including. The method of the present invention will be described with reference to FIG.

  Fig.1 (a) is the figure which showed the place which has built the underground wall around the circumference | surroundings of a structure and the ground which supports a structure. The underground wall 1 shown to Fig.1 (a) can be constructed | assembled using the system shown in FIG. 2, and the stirring member shown in FIG. Details of the stirring member and the system will be described later. The underground wall 1 shown in FIG. 1 (a) is excavated to a predetermined depth without discharging soil, and a solidified material is supplied to the soil, and is stirred and mixed. The inner wall 1 can be constructed. Generally, the foundation of the structure 2 is formed by excavating the ground 3, embedding a reinforcing bar, and placing concrete. Therefore, the foundation of the structure 2 is buried in the ground. In the present invention, the underground wall 1 is constructed around the foundation that is a part of the structure 2 and around the ground 3 a that supports the structure 2. The underground wall 1 may be constructed so as to be adjacent to the foundation or may be constructed so as to be separated from each other. The underground wall 1 is constructed so as to surround the soil of the ground 3a supporting the structure 2 so as to separate the soil of the ground 3a supporting the structure 2 from the surrounding soil.

  Although the underground wall 1 shown to Fig.1 (a) can determine the thickness and the length to the depth direction of the ground 3 suitably according to the construction area, height, etc. of the structure 2, The thickness can be 1 m to 3 m and the depth from the ground surface can be 10 m to 20 m. In addition, it is preferable that the depth from the ground surface is deeper than the depth of the foundation of the structure 2, and it is preferable that it is 2-5 m deep. This underground wall 1 plays the role which raises ground strength and prevents that the chemical | medical solution inject | poured in a later process permeate | transmits widely outside a target range.

  The underground wall 1 shown to Fig.1 (a) can be constructed | assembled using the member and system shown to FIG. 2 and FIG. Specifically, when the stirring member shown in FIG. 3 is rotated and lowered, the soil is excavated and excavated to a predetermined depth. When the stirring member is rotated and raised, at least one solidifying material provided in the stirring member is injected. Slurry containing solidified material or gas in which the solidified material is dispersed in compressed air or nitrogen is supplied from the tube toward the surrounding soil, and the soil and the slurry or gas are mixed by rotating blades provided on the stirring member By doing so, a cylindrical solidified material mixing region can be formed in the soil. The excavation position by the agitation member is changed, the excavation, the supply, the agitation, and the mixing are repeated, and the solidified material mixing region in the columnar shape is formed to overlap, and the soil is solidified by the solidified material. It is possible to construct the underground wall 1 in which a columnar solidified body is continuous around the foundation of 2 and the ground 3 supporting the structure 2. When the solidified material mixing region having a diameter of 2.5 m is formed, the excavation position by the stirring member can be determined so as to overlap at least 0.2 m.

In the present invention, cement, lime, gypsum and the like can be used as the solidifying material. Further, as the solidifying material, gypsum, granulated slag, fly ash or the like can be added to cement, and gypsum, cement, slag powder, fly ash or the like can be added to quick lime or slaked lime. In addition, bentonite, a mixture of the above cement and the like can also be used. The solidifying material can be supplied by being dispersed in a slurry such as cement milk in which cement and water are mixed, or as a powder in compressed air or nitrogen gas. When cement is used as the solidifying material, the amount of cement supplied to 1 m ³ of soil can be 100 kg to 200 kg. For example, when 150 kg of cement is mixed with 1 m ^{3 of} soil, the ground strength after 4 weeks elapses is 3 MPa or more in terms of uniaxial compressive strength.

  FIG.1 (b) is the figure which showed the place which drilled the hole extended to the ground which penetrates an underground wall and supports a structure. The hole 4 shown in FIG. 1 (b) is formed so as to extend to the ground 3 supporting the structure 2 that is surrounded by the underground wall 1 through the underground wall 1 using the boring machine 5. The In the present invention, a plurality of holes 4 can be drilled. In this case, the angle formed by two adjacent holes can be drilled so as to be, for example, 5 ° to 10 °. For example, if the angle is 7 °, the distance between the adjacent ends of two holes drilled by 20 m is about 2.5 m, and this distance is sufficient for the soil interposed between the two holes. The chemical solution can be infiltrated.

  In the present invention, drilling can be performed using a hollow pipe provided with a cutting member at the tip and a plurality of connecting pipes connectable to the hollow pipe. That is, a hollow pipe is attached to a boring machine and drilled to a predetermined position, then one connecting pipe is connected and further drilled, and this is repeated to drill a hole of a predetermined length. . These injection pipes and connecting pipes prevent the ground from being disturbed during drilling, and also prevent soil from entering the pipes and making it impossible to inject chemicals. Water can be supplied. Moreover, what can be used also as a chemical | medical solution injection tube which supplies a chemical | medical solution can be used for a hollow pipe and a connection pipe. Pipes that can also be used as the chemical solution injection pipe are provided with an internal pipe inside the hollow pipe and the connecting pipe, and a hole is provided on the side of the hollow pipe to supply the chemical liquid through the internal pipe. It can be set as the structure which can eject a chemical | medical solution from the hole provided in a part. In the present invention, a drilling pipe or rod that can be bent at an arbitrary position can also be used. In this case, drilling can be started obliquely with respect to the ground surface, and after drilling through the underground wall, the drilling pipe or rod can be bent so as to be parallel to the ground surface. In addition, when using the said pipe or rod for drilling, a sensor is provided in the front-end | tip part, and a drilling position can be detected with the signal from the sensor. For detection, the position can be detected by using a computer and wirelessly communicating with the sensor.

  The hollow pipe and the connecting pipe can be hollow pipes having a predetermined diameter and a predetermined length, and carbon steel pipes or stainless steel pipes can be used. The connection can be performed using a color joint, a socket joint, or the like.

  FIG.1 (c) is the figure which showed the place which ejects the chemical | medical solution which mixed compressed air from the chemical | medical solution injection tube inserted in the hole. After the hole 4 is drilled as shown in FIG. 1 (b), the chemical solution injection pipe 6 is inserted, and the chemical solution is supplied to the chemical solution injection pipe 6, whereby the chemical solution can be sprayed toward the soil. In the case of drilling using the hollow pipe and the connecting pipe that can also be used as the chemical solution injection pipe described above, the chemical solution can be supplied using these pipes. When drilling using a dedicated drilling rod or the like, the chemical solution can be supplied by pulling out the drilling rod and inserting the chemical solution injection tube 6. The chemical liquid injection tube 6 has a hole 7 at the tip side, and the chemical liquid can be ejected from the hole 7. In the present invention, a plurality of holes 7 can be provided in the side portion of the chemical solution injection tube 6, and the chemical solution can be ejected from the plurality of holes 7. In addition, a chemical | medical solution is accommodated in the container 8, for example, using the supply means 9 called a grout pump, and after compressed air is mixed in the middle, it is supplied to the chemical | medical solution injection tube 6. FIG.

  When the above-described hollow pipe and connection pipe are used, after supplying the chemical solution for a predetermined time, the injection of the chemical solution is stopped, one connection pipe is pulled out, and the chemical solution can be supplied for a predetermined time, and this is repeated. Thus, the chemical liquid can be ejected at a plurality of positions in one hole 4. In the present invention, the distance between two adjacent holes approaches the pipe insertion position, that is, as the connecting pipe is removed, the soil volume to which the chemical solution must be injected from one chemical solution injection pipe 6 is reduced. Therefore, the chemical solution supply time can be shortened. For example, if the hole 4 has a length of 20 m, the chemical solution injection pipe 6 is inserted 20 m, and the time for injecting the chemical solution is 3 minutes, the connection pipe is removed and 10 m is inserted. It can be set as the time for injecting the chemical solution in minutes. In the present invention, in addition to the injection time, the injection amount of the chemical solution can be reduced.

  In the present invention, cement milk, cement bentonite liquid or the like can be used as the chemical liquid. In addition, a material mainly composed of alkali metal silicate, silicate gel, calcium silicate, or the like can be used. A water glass can be mentioned as a chemical | medical solution which has an alkali metal silicate as a main component. In the present invention, the chemical solution is supplied together with the compressed air. In addition, it is preferable that compressed air is supplied in the state mixed with the chemical | medical solution as a bubble, and is injected from the chemical | medical solution injection tube 6. FIG. Compressed air can widen the gaps between soil particles, and can easily displace moisture and gas contained in the soil and replace them with chemicals, allowing it to penetrate into a wide range. Further, by expanding the gap and forming a space, it is possible to inject a larger amount of the chemical solution and to strengthen the ground by making the soil dense. Furthermore, the chemical solution is pushed up toward the ground surface, and moisture and gas contained in the soil are discharged onto the ground surface. The present invention can obtain a high-strength ground by substituting and solidifying moisture and gas contained in soil with a chemical solution. The compressed air is supplied from a compressed air supply means (not shown), mixed in a chemical solution in a mixing device (not shown), and the chemical solution mixed with the compressed air is injected from the hole 7 of the chemical solution injection pipe 6.

In the present invention, when the chemical liquid cement milk, to soil 1 m ^3, may be 0.01 m 3 0.5 m ^3. When the distance between the two adjacent holes described above is about 2.5 m, injection per 1 m is performed at that position (tip position of the chemical injection pipe 6 when 20 m of the chemical injection pipe 6 is inserted into the hole 4). When the amount of soil to be targeted is about 2.5 m ³ and is injected at a rate of 0.01 m ³ per minute, it can be 2.5 to 125 minutes. The injection pressure is preferably as high as possible in order to spread over a wide range, but if it is too high, there is a possibility that ground cracking or the like may occur due to mixed compressed air, so 0.7 MPa is preferable, for example.

  FIG. 2 is a schematic view of a system used for constructing an underground wall in the ground improvement method of the present invention. Here, a case where a slurry prepared by dispersing a solidifying material in water is used will be described. The system shown in FIG. 2 includes a stirring member 13 having a cutting member 10 at a tip portion, a spiral blade 12 and a solidifying material injection pipe (not shown) for supplying slurry to a peripheral portion of a shaft body 11, and a stirring member 13 Supporting means 14 having a line connected to a solidifying material injection pipe or the like of the stirring member 13, a container 15 in which slurry is accommodated, and a container 15 connected to the container 15. , A supply means 16 for supplying the slurry, and a line 17 for supplying the slurry. In order to supply compressed air during excavation, the system further includes a compressed air supply means and a compressed air supply line (not shown).

  A stirring member 13 shown in FIG. 2 has a cutting member 10 for excavating soil at a tip portion facing in the excavation direction, and a shaft body 11 that allows compressed air to be injected from the tip portion in the excavation direction. And the spiral blade 12 that is provided around the shaft body 11 that enables the excavation to be performed smoothly and that can stir the soil, and the spiral so as to penetrate from the inside of the shaft body 11 to the outside. And at least one solidifying agent injection pipe (not shown) disposed toward the edge of the blade 12. The stirring member 13 is connected to the rod 18, and the soil can be excavated and the soil can be stirred by the rotation and elevation of the rod 18. Injecting compressed air through the shaft body 11 to reduce the impact on the ground during excavation, to give the agitating member 13 a rocking agitation effect to facilitate excavation, and to suppress heat generation during excavation of the cutting member 10 Can be done. This compressed air is supplied from a compressed air supply means (not shown) through a compressed air supply line (not shown). In addition, in order to supply the slurry and disperse it into the soil to purify the soil, the slurry can be supplied from the solidification material injection tube to the soil together with the stirring of the soil by the spiral blades 12. ing. The agitating member 13 can change the direction of rotation so as not to discharge soil during descent during excavation and during ascending and descending during agitation. The details of the stirring member 13 will be described below with reference to FIG.

  The support means 14 shown in FIG. 2 supports the traveling part 19, the rod 18, the clamping part 20, the rod 18, the arm 21 that can change the angle of the rod 18, and the lifting / lowering that allows the rod 18 to move up and down. And means 22. The traveling unit 19 is moved toward the soil position where the solidifying material is to be supplied next, and the position can be changed. The rod 18 enables rotation and elevation of the stirring member 13 disposed at the lower end facing the ground. The clamping part 20 clamps the rod 18 so that movement and rotation are possible. The clamping unit 20 can rotate the rod 18 in both forward and reverse directions by hydraulic drive or the like.

  The rod 18 shown in FIG. 2 connects a line 17 for supplying the slurry and a line for supplying the compressed air, and a line for connecting the shaft body 11 of the stirring member 13 and the solidifying material injection pipe. I have. The line provided inside the rod 18 has two lines corresponding to the two lines. The rod 18 can be connected to another rod depending on the depth of the soil.

  A container 15 shown in FIG. 2 is provided to contain water and a solidifying material, and to disperse the solidifying material in water to create a slurry. The slurry may be stored in the container 15 after being prepared in another container. Moreover, a dispersing agent can also be added to a slurry so that a solidification material may disperse | distribute easily. A stirring means (not shown) is provided inside the container 15, and the state where the solidified material is dispersed can be maintained by constantly stirring the slurry. The slurry in the container 15 is discharged from the lower part of the container 15, and a predetermined amount of slurry is supplied by the supply means 16.

  When supplying the solidified material together with the compressed air, a predetermined amount of the solidified material is placed in the container 15 and controlled to be discharged by a valve or the like. For example, a predetermined amount of the solidified material can be supplied by supplying a predetermined amount of compressed air to the lower portion of the container 15 and dropping a predetermined amount of the powdered solidified material into the compressed air. Since clogging may occur during discharge, a part of the compressed air is supplied to the container 15 to pressurize the inside, or a vibrator is disposed on the side of the container 15 to shake the container 15. Can be moved.

  In the present invention, the container 15 may have any capacity and may have any shape. Moreover, the container 15 can use steel hoppers, such as stainless steel, for example. When the inside is pressurized, a lid can be provided on the top. As the supply means 16, any pump can be used as long as it can supply a slurry in which a solidifying material is dispersed in water. Moreover, when supplying using compressed air, the supply means 16 can be made into an air compressor, an air cylinder, or an air curd, and in the case of nitrogen, it can be made into a nitrogen cylinder or a nitrogen curd.

  FIG. 3 is a view showing a stirring member used in the system shown in FIG. FIG. 3A is a perspective view of the stirring member 13, and FIG. 3B is a cross-sectional view. The agitating member 13 shown in FIG. 3 includes a hollow pipe body 11 having a tip conduit 30 provided with a cutting member 10 at the tip and a diameter at the center along the length direction and a diameter at both ends reduced. The spiral blades 12 provided around the outer surface of the shaft body 11, the plurality of projecting members 31 provided on the upper and lower surfaces of the spiral blade 12, and the diameter of the shaft body 11 in the length direction are increased. Further, it is composed of two solidification material injection pipes 32 and 33 that pass through the shaft body 11 at the central portion and are arranged toward the edge of the spiral blade 12. In the present invention, the number of solidifying material injection pipes 32 and 33 may be one, or three or more.

  The tip conduit 30 shown in FIG. 3 is connected to the shaft body 11 using a connecting member such as a flange 34, and the cutting member 10 is provided at the tip. The flange 34 is also provided with a cutting member 10 a so as to face the same direction as the cutting member 10. The cutting members 10 and 10a shown in FIG. 3 are provided with sharply pointed tips, which can cut hard soil, stones, and the like, and are welded to the tip of the tip conduit 30 and the flange 34. Can be joined together. The tip conduit 30 shown in FIG. 3 may be a pipe having any diameter and length, but can have the same diameter as that of both ends of the shaft body 11. Further, the shape, structure and material of the cutting members 10 and 10a may be any as long as they can excavate the soil appropriately. Further, any number of the cutting members 10 and 10a may be provided at the tip portion of the leading conduit 30 and the flange 34.

  The shaft body 11 shown in FIG. 3 has a shape in which the diameter of the central part is increased, the diameter is constant at a predetermined length of the central part, and the diameter is reduced at a constant rate toward both ends. It is said that. Moreover, it is hollow and a part of the solidification material injection pipes 32 and 33 for supplying the slurry therein is inserted. Compressed air is allowed to flow in the space excluding the solidifying material injection pipes 32 and 33, reducing the impact on the ground during excavation, and giving the agitating member 13 a rocking agitation effect for excavation. While making it easy, it is possible to suppress the heat generation of the cutting member 10. In the present invention, for example, the shaft 11 has a constant diameter of 0.8 m as a whole, a constant diameter of 0.4 m at a center length of 0.16 m, and 0 in a range of 0.32 m at both ends in the length direction. A structure that is enlarged at a constant rate from a diameter of .14 m to 0.4 m can be obtained. In this case, the taper angle that expands at a constant rate is 22 °.

  The shaft body 11 shown in FIG. 3 is provided with a spiral blade 12 formed in a spiral shape on the outer surface. The spiral blade 12 is formed so that the diameter of the spiral blade 12 increases toward the center of the shaft body 11, and a plurality of projecting members 31 are provided on the upper and lower surfaces of the spiral blade 12. . Similar to the shaft body 11, the spiral blade 12 is formed so that the diameter of the blade increases from both end portions in the length direction of the shaft body 11 toward the central portion, and smoothly moves up and down in the soil. The structure can be agitated. In the present invention, as long as mixing and stirring can be performed, the shape is not limited to the spiral blade 12, and any shape blade may be used.

  The protruding member 31 shown in FIG. 3 is a rectangular plate, and is disposed so that the rectangular surface faces the shaft body 11. Further, the protruding member 31 is provided at the edge of the spiral blade 12 and the inner edge near the shaft body 11 and has a structure in which rectangular corners are chamfered. By adopting a structure in which the corners on the side facing the rotation direction of the rectangular plate-like projecting member 31 are chamfered, the spiral blade 12 can be smoothly rotated and effectively stirred. In the stirring member 13 shown in FIG. 3, when excavating the soil, the protruding member 31 provided on the lower surface of the spiral blade 12 sharply impregnates the soil while effectively stirring the soil, and the protruding member 31 provided on the upper surface. Can smoothly feed the cut and agitated earth and sand, and even if the soil contains stones and the like, it is difficult to chew. When the stirring member 13 is raised from the ground toward the ground surface, the protruding member 31 provided on the upper surface of the spiral blade 12 effectively cuts and stirs, and the protruding member 31 provided on the lower surface. Can smoothly send earth and sand backwards. Therefore, when excavating soil using the stirring member 13 shown in FIG. 3, the excavated earth and sand are not discharged to the ground. In the present invention, any number of the protruding members 31 may be provided, and the shape is not the rectangular plate shape described above, and the rectangular plate is bent along the spiral shape of the spiral blade 12. May be.

  In the hollow portion of the shaft body shown in FIG. 3, a part of the solidifying material injection pipes 32 and 33 is inserted as described above, and the hollow portion of the shaft body 11 other than the solidifying material injection pipes 32 and 33 is Compressed air can be passed. The solidifying material injection pipes 32 and 33 shown in FIG. 3 are bent vertically at the center in the longitudinal direction of the shaft body 11, penetrate the shaft body 11, and the edge of the spiral blade 12. It has a structure extending toward the part. Further, the solidifying material injection pipes 32 and 33 are arranged so that the solidifying material injection pipe 33 penetrates one surface of the shaft body 11, that is, the back surface of one surface thereof, that is, the solidifying material injection pipe 33. It is provided at an angle of 180 ° in the circumferential direction from the protruding position. In the present invention, the respective solidifying material injection pipes 32 and 33 are located at the same position in the length direction of the shaft body 11 so that the slurry can come into contact with the soil and appropriately cause the decomposition reaction of the pollutant. It is preferable that the lengths projecting from the shaft body 11 along the spiral blade 12 are the same. In addition, the diameter of the solidification material injection pipes 32 and 33 may be any diameter, and, for example, a 1 to 1.5 inch diameter can be used.

  In the present invention, the solidifying material injection pipes 32 and 33 do not need to extend to the edge of the spiral blade 12, and may be up to the center or inner edge of the spiral blade 12. In the present invention, since the solidified material is mixed with the soil, the slurry may be simply supplied. However, the slurry may be supplied at a high pressure and injected from the solidified material injection pipes 32 and 33. In this case, it is preferable that the solidifying material injection pipes 32 and 33 extend to the edge of the spiral blade 12 in order to spray over a wide range. In addition, the solidification material mixing area | region of the said about 2.5 m diameter can be formed by using the thing of the diameter of the center part which becomes the largest of the helical blade | wing 12 about 1.5 m.

  FIG. 4 is a cross-sectional view of the ejector device 40 used in the mixing device. The mixing device is used in the chemical solution injection, and includes an ejector device 40. An ejector device 40 shown in FIG. 4 is installed between the boring machine 5 and the supply means 9 shown in FIG. 1 (c), and includes an outer tube 41, an inner tube 42 disposed inside the outer tube 41, A flow path reducing portion 43 and a branching portion 44 are provided. The flow path reducing portion 43 forms a taper that makes the flow path smaller, and the chemical solution is ejected through the opening 45 having the smallest flow path. The inner tube 42 is disposed so as to face the opening 45, and a chemical solution flowing through the opening 45 flows through the inner tube 42. In the embodiment shown in FIG. 4, the diameter of the inner tube 42 facing the opening 45 is expanded so that the chemical liquid flowing through the opening 45 flows appropriately through the inner tube 42. Further, a branch portion 44 is provided at a predetermined position of the outer tube 41 so that compressed air is supplied toward the outer tube wall of the inner tube 42, and the compressed air supplied through the branch portion 44 is connected to the outer tube 41. It passes between the inner pipes 42 and is supplied along the taper in the direction opposite to the direction of the flow of the chemical solution. Thereby, the compressed air is appropriately mixed as bubbles in the chemical liquid injected through the opening 45. The chemical liquid containing bubbles is supplied through the inner tube 42 to the boring machine 5 shown in FIG. In the present invention, by containing compressed air in the form of bubbles in the chemical solution, the above-described gap can be appropriately expanded, and water and gas contained in the soil are appropriately expelled and the chemical solution is supplied to the expelled space. can do. If the air is not supplied in a bubble state, the compressed air and the chemical solution are supplied in a two-phase state. When discharged from the discharge port, the compressed air is supplied upward and the chemical solution is supplied downward. The In this case, in the soil to which only the chemical solution is supplied, the gap cannot be widened, and moisture and gas contained in the soil cannot be expelled, and the chemical solution cannot be spread over a wide range.

  The process of constructing the underground wall using the system and the stirring member shown in FIGS. 2 and 3 will be described in detail. First, the rod 18 is disposed at a position to be purified by the traveling unit 19, and the arm 21 is used to adjust the rod so that it is perpendicular to the ground. The rod 18 is rotated by the clamping unit 20 and the rod 18 is lowered by the lifting means 22 to excavate the soil. The excavation of the soil can be performed using the cutting member 10 provided at the tip of the stirring member 13. In addition, compressed air is supplied from the compressed air supply means in order to reduce the impact on the ground during excavation and to give excavation stirring effect to the stirring member 13 to facilitate excavation. The compressed air passes through a compressed air supply line (not shown), and is jetted from the tip through the line in the rod 18 and the shaft 11 of the stirring member 13. In addition, the jet of compressed air has the effect of preventing the soil from entering the shaft body 11 in addition to the rocking stirring effect of the stirring member and the cooling effect of the cutting member 10. When the length of the rod 18 is insufficient, the rod 18 is stopped from rotating by the clamping portion 20, the connecting portion connecting the rod 18 and the line 17 is removed, and the rod extending between the connecting portion and the rod 18 is removed. Can be connected. After connection, the rod 18 can be rotated again to continue excavating the soil.

  In the present invention, a hole to the extent that the stirring member 13 enters is excavated in advance, and the earth and sand generated by the excavation are temporarily placed in another place so that the earth and sand rising during excavation by the stirring member 13 does not overflow from the hole. It can also be. This temporarily placed earth and sand can be backfilled by adding a predetermined amount of solidifying material using a backhoe or the like, mixing, and mixing.

  Next, after excavating the soil to a predetermined depth, the direction of rotation of the rod 18 by the clamping unit 20 is changed. Do not raise until the slurry is supplied, but keep rotating. In the present invention, the rotation of the rod 18 can be stopped. The supply means 16 is activated and the supply of slurry from the container 15 is started. For example, the slurry from the container 15 to the supply unit 16 can be filled in advance, and the slurry can be supplied to the stirring member 13 by starting the supply unit 16.

  When the slurry is supplied to the stirring member 13, as shown in FIG. 2, the slurry is supplied from the respective injection tubes toward the soil. The slurry is continuously supplied in the circumferential direction of the spiral blade 12, and the soil is further stirred by the rotating spiral blade 12 to mix the slurry and the soil. Next, the rod 18 is raised at a predetermined speed by the elevating means 22 while supplying the slurry and stirring by the spiral blade 12. By carrying out like this, a solidification material can be uniformly supplied to the soil to the predetermined depth in the original position, without accompanying soil. In the present invention, in order to sufficiently mix the soil and the solidified material, it is preferable that the rising speed is small. However, if it is too small, the working efficiency is lowered. For example, at 0.05 m / min to 0.3 m / min. Can be raised.

  In the present invention, when the stirring member 13 rises to the vicinity of the ground surface, the supply means 16 is stopped, and the supply of compressed air by the compressed air supply means is stopped. However, the compressed air injected from the tip end of the shaft 11 of the stirring member 13 is continuously supplied for the next excavation. After the stirring member 13 is further raised and the stirring member 13 is separated from the ground surface, the next excavation position, that is, a position determined so that a part of the solidified material mixing region overlaps by the traveling unit. And excavation, slurry supply, and agitation can be performed again as described above. The excavation position is preferably determined so that a part of the solidified material mixing region 50 overlaps, for example, as shown in FIG. In FIG. 5, the solidified material mixing region 50 is indicated by a solid line, and the rotation region 51 of the spiral blade 12 of the stirring member 13 is indicated by a broken line. For example, the rotation area 51 by the spiral blade 12 is a circle having a diameter of about 1.5 m centering on the shaft body, and the solidifying material mixing area 50 is a circle having a diameter of about 2.5 m. The reason why the solidifying material mixing region 50 is wider than the rotation region 51 is that slurry is injected from the solidifying material injection pipes 32 and 33, and not only the soil adjacent to the spiral blade 12 but also the soil adjacent thereto rotates the spiral blade 12. This is because of stirring.

  One region 50a is formed by performing the drilling, feeding, stirring and mixing steps using the system and stirring member shown in FIGS. In the present invention, the next position is determined so as to overlap with a part of one region 50a, and similar steps are executed to form a continuous region 50b. As shown in FIG. 5, the operation is performed so as to surround the structure 2, and the soil wall is solidified by the solidifying material after the lapse of a predetermined period, whereby the underground wall 1 is constructed. The underground wall 1 has a structure in which a plurality of solid cylindrical bodies are continuous, and separates the soil on the ground supporting the structure 2 from the surrounding soil. In the present invention, it is preferable to use the above system in that the underground wall 1 can be constructed by excavating to a predetermined depth without discharging soil, supplying slurry, and mixing them. The underground wall 1 can also be constructed by excavating and mixing the solidified material and then backfilling.

  FIG. 6 is a diagram showing a shaft constructed adjacent to the underground wall after the underground wall has been constructed. The ground improvement method of the present invention may further include a step of constructing the shaft 60. The shaft 60 can be constructed adjacent to or adjacent to the underground wall 1. The construction of the shaft 60 is particularly that the hole 4 can be drilled directly toward the soil adjacent to the structure 2 (soil immediately below the structure), and chemicals can be supplied to the soil. preferable. The vertical shaft 60 can be constructed in a predetermined shape using excavation means such as the backhoe described above.

  6A shows a cross-sectional view in which the underground wall 1 is constructed around the foundation of the structure 2 and the shaft 60 is constructed adjacent to the underground wall 1, and FIG. The plan view is shown. In addition, in FIG. 6, the several hole 4 is also shown with a continuous line. The structure 2 has a cylindrical shape, and a foundation is buried in the ground. A hollow substantially cylindrical underground wall 1 is constructed so as to surround the periphery of the foundation. Two shafts 60 having an area where the boring machine 5 can be installed adjacent to the underground wall 1 are constructed to face each other with the structure 2 therebetween. In the present invention, the underground wall 1 having a thickness of 2.5 m and a depth of 10 m can be constructed, and the shaft 60 having a width of 5 m, a depth of 5 m, and a depth of 2 m can be adjacently constructed. A boring machine 5 is installed in the shaft 60, and a plurality of holes 4 penetrating the underground wall 1 are drilled. In the present invention, as described above, each hole can be drilled so that the angle α formed by two adjacent holes is 5 ° to 10 °. The holes 4 are drilled so as to penetrate the underground wall 1 in each of the vertical holes 60, as shown in FIGS. 6 (a) and 6 (b).

  Although the present invention has been described in detail with the above-described embodiment, the ground improvement method of the present invention is not limited to the above-described embodiment, and the same effect can be obtained. The stirring member is not limited to the shape described above, and may have any size, the number of turns of the spiral blade, the position where the iron powder and oxidant injection pipes are disposed, and the container may have any shape and structure. Also, the mixing ratio and supply amount of solidifying material such as cement, lime, gypsum and the amount of water, the type of chemical solution, the injection amount of the chemical solution depends on the moisture content of the soil, the ground strength, the angle formed by the two adjacent holes, etc. It can be set to an appropriate value. In order to measure the amount of the injected chemical at the time of injecting the chemical, a level gauge can be provided in the container for storing the chemical.

The figure which illustrated each process of the ground improvement method of the present invention. The figure which illustrated the system for carrying out the process of constructing an underground wall. The figure which showed the stirring member used for the system shown in FIG. The figure which showed the mixing apparatus used when inject | pouring a chemical | medical solution. The figure which showed each position which excavates soil, supplies a slurry, and mixes a soil and a slurry in the process of constructing an underground wall using the system shown in FIG. The figure which showed the place which constructed the shaft and drilled several holes from the shaft.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ground wall 2 ... Structure 3, 3a ... Ground 4 ... Hole 5 ... Boring machine 6 ... Chemical injection pipe 7 ... Hole 8 ... Container 9 ... Supply means 10, 10a ... Cutting member 11 ... Shaft body 12 ... Spiral shape Blade 13 ... Stirring member 14 ... Supporting means 15 ... Container 16 ... Supply means 17 ... Line 18 ... Rod 19 ... Traveling part 20 ... Clamping part 21 ... Arm 22 ... Lifting means 30 ... Pre-conduit 31 ... Protruding members 32, 33 ... Injection Pipe 34 ... Flange 40 ... Ejector device 41 ... Outer pipe 42 ... Inner pipe 43 ... Flow path reducing part 44 ... Branching part 45 ... Opening part 50 ... Solidified material mixing area 50a, 50b ... Area 51 ... Rotating area 60 ... Vertical shaft

Claims (10)

Supplying a solidifying material to the soil around the structure, mixing the soil and the solidified material, and constructing an underground wall surrounding the structure and the ground surrounding the structure;
Drilling a hole that extends through the underground wall to the ground supporting the structure;
And a step of spraying a chemical liquid mixed with compressed air from a chemical liquid injection tube inserted into the hole.   The method further includes the step of excavating the soil adjacent to the underground wall and constructing a shaft, and the drilling step extends from the shaft to the ground that supports the structure through the underground wall. The ground improvement method according to claim 1, wherein the hole is drilled. The step of constructing the underground wall includes a stirring member including a cutting member at a tip portion, a blade at a peripheral portion, and at least one solidifying material injection pipe disposed toward an edge of the blade, A step of excavating the soil by rotating and lowering by a support means for supporting the stirring member rotatably and ascending and descending;
While rotating and raising the stirring member, a slurry containing the solidification material or a gas in which the solidification material is dispersed in compressed air or nitrogen is supplied from the at least one solidification material injection pipe toward the soil. Process,
Mixing the soil and the slurry or the gas by rotating the blades,
Repeating the excavating step, the supplying step, and the mixing step, and constructing the underground wall in which a columnar solidified body is continuous around the structure and the ground supporting the structure. The ground improvement method according to claim 1, wherein the ground improvement method is characterized.   In the excavating step, the stirring member is rotated in a predetermined direction to excavate to a predetermined depth of soil and the soil is stirred, and in the supplying step and the mixing step, the stirring member is defined as the predetermined direction. The ground improvement method according to claim 3, wherein the slurry is rotated in the reverse direction to be raised toward the ground surface, the slurry or the gas is supplied, and the soil is stirred.   The stirring member includes a tip conduit provided with the cutting member at a tip portion, a hollow shaft body to which the tip conduit is connected, a spiral blade provided around the shaft body, an upper surface of the spiral blade, and A plurality of projecting members disposed on the lower surface and disposed through the inside of the shaft body, disposed through the shaft body toward the edge of the spiral blade, and supply the slurry or the gas The shaft body is formed so that the diameter is large at the center along the length direction and the diameter is small at both ends. The ground improvement method of Claim 3 or 4 characterized by these.   The support means includes a traveling part for moving, a rod for connecting the stirring member, a holding part for rotating the rod in both forward and reverse directions and supporting the rod, and an elevating means for raising and lowering the rod. And the excavating step includes a step of rotating the rod by the clamping unit and a step of lowering the rod by the elevating means, and the supplying step and the mixing step rotate the rod by the clamping unit. The ground improvement method according to any one of claims 3 to 5, further comprising a step of raising the rod by the lifting means.   The chemical solution injection pipe is composed of a hollow pipe having a cutting member at a tip portion and a plurality of connection pipes connectable to the hollow pipe. In the step of drilling, the hole is drilled and the The connecting pipe is connected, and in the step of injecting, the connected pipe is removed every time the chemical solution is injected for a predetermined time. The ground improvement method of description.   In the jetting step, the chemical liquid is jetted and the compressed air is supplied in a direction opposite to the flow direction of the chemical liquid, thereby mixing the compressed air as bubbles in the jetted chemical liquid. The ground improvement method of any one of Claims 1-7.   Two shafts are constructed so as to face each other through the structure. In each shaft, a plurality of holes are drilled so that an angle formed by two adjacent holes is 5 ° to 10 °. The ground improvement method according to claim 2, wherein:   The ground improvement method according to claim 1, wherein the hole is formed to have a curved portion.

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