JP5156989B1 - Ground improvement method and ground improvement equipment - Google Patents

Abstract

[Problem] To provide a ground improvement method and a ground improvement device capable of performing ground improvement by injecting a chemical solution very efficiently by performing ground investigation, boring and ground injection as a series of continuous work processes. To do.
A casing rod for drilling, a bundling injection pipe installed in the casing rod and penetrating into the ground together with the casing rod, and bundling the casing rod by continuous striking by a natural fall of a hammer. It consists of an automatic continuous striking device 2 that penetrates into the ground together with the injection tube, and a counter 9 that records the number of times of striking of the casing rod 1 by the hammer 7 with a certain amount of penetration. The casing rod 1 is pulled out after penetrating into the ground. An injection material is injected into the ground after pulling out the casing rod 1 through a bundle injection tube.
[Selection] Figure 1

Description

  The present invention relates to a ground improvement method and a ground improvement device mainly used for liquefaction countermeasures, and in particular, in a single land divided into a plurality of areas, such as a residential area such as a subdivision where a detached house is densely built, a gas pipe, It is possible to easily carry out liquefaction countermeasures and ground improvement of ground where lifelines such as water pipes and sewer pipes are laid.

  As a liquefaction countermeasure in a residential area, there is known a chemical liquid injection method in which an injection pipe is inserted into a drilling hole formed by boring after a ground survey and the ground is injected through the injection pipe.

  In this case, the ground survey uses a method that uses a machine that dynamically penetrates the steel pipe into the ground, such as an automatic ram sounding tester or a single pipe driven well, and rotary percussion is used for boring. Is used. Rotary percussion is said to be particularly suitable for boring on the ground such as large depths of 30m or more and raked ground.

JP 2010-242343 A JP 2010-242369 A JP 2012-21269 A Japanese Patent Laid-Open No. 2003-90032

  However, in the seismic reinforcement of lifelines such as gas pipes and water and sewage pipes, economic efficiency, workability, and rapid construction are important.

  Especially, in the ground where the improvement layer is shallow and the soil contains a sand with a silt layer or a lot of sand with a sand layer, the drilling by rotary percussion is too expensive, and the cost increases for the construction scale, In confined places such as residential land, there were problems such as when it was difficult to load and install machines.

  In addition, prior to boring, there is a problem that work efficiency is poor because it is necessary to use a dedicated device and perform ground surveys in a separate process.

  Furthermore, in recent earthquake disasters, it is extremely difficult to take measures against liquefaction, especially in residential areas such as subdivisions where single-family houses are densely built, or in residential areas adjacent to public roads. Met.

  The reason is that even if only one section is improved, if the other sections are liquefied, the living functions of the entire area are lost. In addition, carrying various devices necessary for ground improvement work into a densely populated residential area not only hinders the lives of residents, but also may contaminate the residential area.

  The present invention has been made to solve the above-described problems, and effectively implements countermeasures against liquefaction while using a lifeline extending in a linear shape such as a gas pipe, a sewer pipe, a water pipe, and a telephone line. Also, in liquefaction countermeasures such as harbors, revetments, railways, etc., we provide technology that allows continuous construction by arranging one or more injection lines along these facilities, Even in a liquefaction countermeasure work on a site having a large area such as an airport, it is possible to continuously improve the ground by arranging one or a plurality of injection lines.

  In particular, liquefaction countermeasures can be carried out in a well-balanced, effective and economical manner in a residential area where a number of detached houses are densely lined up, such as subdivisions. It is possible to perform ground survey, drilling, injection pipe installation, and ground injection of this construction as a series of continuous work processes using the same equipment, and to perform construction while using a lifeline An object of the present invention is to provide a possible ground improvement method and a ground improvement device.

  The ground improvement apparatus of the present invention penetrates a casing rod for drilling with a built-in injection tube into the ground together with the injection tube by continuous hammering, and records the number of times the hammer hits the casing rod at a constant penetration amount. The injection rod is left in the ground, the casing rod is pulled out, and the injection material is injected into the ground after the casing rod is pulled out through the injection pipe. Is.

  According to the present invention, each of the ground investigation, boring, injection pipe installation, and original chemical injection performed in advance by ground improvement by chemical injection is performed by the same apparatus and as a series of continuous work processes. As a result, the ground improvement by the chemical solution injection can be performed very efficiently.

  In addition, it is possible to grasp the general ground condition from the state of penetration of the casing rod by continuous hammering and the like, so that the optimum composition and the optimum amount of the injection material can be injected.

  Furthermore, the value (Nd) obtained by correcting the number of hits per 20cm of penetration obtained by letting a hammer with a mass of 63.5kg drop naturally from a height of 50cm and penetrating the casing rod into the ground is the standard penetration. Since it can be evaluated almost equal to the N value of the test, a more accurate ground condition can be grasped.

  In particular, ground improvement within a depth of 10 m, which is relatively close to the ground surface, can be easily and effectively performed over a wide range in liquefaction countermeasures and the like.

  The injection rods of the casing rod for drilling holes and the bundling injection tube are both formed by detachably connecting a plurality of units formed in a short length of about 1 to 4 m. The length can be set arbitrarily according to the depth, and handling is facilitated during transportation and storage. Of course, one injection tube can be built in one casing rod in accordance with the improved depth and ground conditions.

  In addition, a plurality of injection tubules are bundled in the tube axis direction to form a bundled injection tube, and the injection material discharge ports at the tip of each injection tubule are arranged at intervals in the tube axis direction to inject into a plurality of formations. The material can be injected simultaneously.

  The injection material is silica injection chemical, clay injection, clay cement injection, or microbubble, gas from compressor, silica grout mixed with bubbles, soil purification agent, slag injection, cement slag injection. A material etc. can be used.

The ground improvement method according to the present invention is the ground improvement method using the ground improvement device according to claim 1 or 2, wherein a casing rod for drilling with a built-in injection pipe is penetrated into the ground together with the injection pipe by a hammer. the hammer and record the number of hits per predetermined penetration of the casing rods by the injection tube punching pull the casing rod leaving in the ground, and the injection tube in the ground after withdrawal of the said casing rod it is characterized in that injecting the injection material through.
In addition, an injection tube is arranged at each of a plurality of injection points, and the injection tube at each injection point is connected to an injection material manufacturing plant via an injection pump, a pressure / flow rate detector, and a liquid supply tube, and these are connected by a controller. By batch control, ground injection at multiple injection points can be performed simultaneously or by selecting one or more injection points. At each injection point, a casing rod for drilling with a built-in injection tube is connected to the hammer continuously. It penetrated into the ground together with the injection pipe by striking, recorded the number of times the hammer was struck by a constant penetration amount of the casing rod, pulled out the casing rod leaving the injection pipe in the ground, and pulled out the casing rod The injection material is injected into the ground after that through the injection pipe.

  By filling the casing rod with a low-strength sealing material made of cement-based slurry, clay-based slurry or the like, it is possible to prevent hole wall collapse after the casing rod is pulled out.

  Further, the gap between the injection tube and the hole wall can be sealed by filling the sealing material to prevent the injection material from being discharged to the ground surface.

  In addition, as shown in FIG. 5 (a), the ground improvement devices are arranged at a plurality of injection points, and the injection pipes of the local improvement devices are inserted into the ground at each injection point. Based on the ground survey results, the injection pipe is connected to the injection material production plant from the injection and management unit 21 via the injection pump, pressure / flow rate detector, and liquid supply pipe, and these are collectively controlled by the controller. By performing ground injection at a plurality of injection points simultaneously or selectively and optimally, liquefaction countermeasures in a certain region can be performed extremely efficiently and reliably.

  Further, as shown in FIG. 5 (b), a plurality of ground improvement devices are installed on the ground where a laying structure that is linearly continuous in one direction such as a gas pipe and a water and sewage pipe is installed. Place one row or laying object at regular intervals along the object in multiple rows on both sides or on the line, and inject the injection pipes of the local improvement devices into the ground respectively, and the injection pipes of the local improvement devices Is connected to the injection material production plant, the injection pump, and the pressure / flow rate detector through one or more liquid supply pipes, and the injection, selection of injection points, injection sequence, etc. are controlled by the controller in a batch. Therefore, it is possible to perform injection at multiple injection points at the same time or at multiple injection points at the optimal injection volume, injection speed, injection sequence, and optimal injection depth according to the ground survey results. In addition, liquefaction measures around these laying structures can be performed extremely efficiently and reliably.

  In addition, a ground displacement sensor is placed at a predetermined position to monitor the ground structure, laying material, and underground buried material from being damaged by the ground displacement caused by the injection, and the injection is stopped through the controller and other injection points By switching the injection, etc., it is possible to prevent deformation, damage, etc. due to injection of overground structures, laying structures, underground structures, etc., and prevent damage to surrounding structures, and easily take measures to prevent liquefaction. It can be carried out.

  In this case, ground injection as a countermeasure against liquefaction does not necessarily have to be performed over the entire length of the lifeline such as a gas pipe, a sewer pipe, and a water pipe. In the case of these lifelines, the ground support is injected into each joint (connecting part) between the laying pipes that are liable to break down due to liquefaction during an earthquake, and a solid support body that supports the joint part between each laying pipe in the ground. It may be formed.

  In this way, lifeline where liquefaction countermeasures have been made, even if liquefaction occurs in the surrounding ground, the joint part of each laying pipe is supported by the solidified support, so that the elasticity of the pipe itself Will cause some deflection but will not lead to destruction.

  According to the present invention, it is possible to perform each of the preliminary ground investigation, boring, and original chemical injection performed as countermeasures for liquefaction by chemical injection with the same apparatus and as a series of continuous work steps. The liquefaction countermeasure work by injection can be performed very efficiently.

  In addition, it is possible to grasp the general ground condition from the penetration state of the casing rod by continuous hammering, etc., so that the optimum composition and the optimal amount of injection material can be injected into the formation where liquefaction is expected. it can.

FIG. 1 (a) is a front view and FIG. 1 (b) is a side view showing an embodiment of the ground improvement device of the present invention. Fig. 2 (a) is a longitudinal sectional view of the distal end portion, Fig. 2 (b) is a transverse sectional view, and Fig. 2 (c) is a casing rod distal end portion containing a single injection tube. It is sectional drawing. FIG. 3 (a) to FIG. 3 (d) are longitudinal sectional views of the tip portion of the casing rod showing the construction procedure of the ground improvement method of the present invention. It is a columnar figure created by estimating from the number of hits for every 20 cm of penetration depth of the casing rod that penetrates by continuous hitting due to the natural fall of the hammer. FIG. 5 (a) is a plan view of the ground showing a method for performing ground injection by placing ground improvement devices at a plurality of points, and FIG. Fig. 5 (c) is a ground plan view showing a method for continuously injecting ground by placing the improved equipment at multiple points on the ground where the lifeline extends linearly, such as a gas pipe. It is the longitudinal cross-sectional view of the ground which shows the method of arrange | positioning in multiple points of the laying ground of the lifeline extended linearly, such as a pipe | tube, and performing ground injection continuously. FIG. 6 is a vertical sectional view of the ground showing the ground improvement method shown in FIGS. 5 (a) and 5 (b). This is a vertical cross-sectional view of the ground showing how to improve the ground by placing ground improvement devices at multiple points on the laying ground of the lifeline extending linearly, such as water pipes, and continuously injecting injection material into each injection point is there. Figures 8 (a) and 8 (b) show how to improve the ground by placing multiple injection pipes around the structure and injecting the injected material into the ground directly below the structure from each injection point. FIG.

  1 and 2 show an embodiment of the ground improvement device of the present invention, FIG. 1 is a front view of the ground improvement device, and FIG. 2 is a side view. In the figure, reference numeral 1 is a casing rod penetrating into the ground, 2 is directly above the casing rod 1, and an automatic continuous striking device for penetrating the casing rod 1 into the ground by continuously striking the casing rod 1. The mast supports the automatic continuous striking device 2 so as to be movable up and down and guides the casing rod 1 vertically on the ground surface via the guide member 4. Reference numeral 5 denotes a bundling injection pipe for injecting an injection material into the ground for each of a plurality of layers.

  The casing rod 1 is formed of a plurality of casing rod units 1a. The casing rod unit 1a is formed to a length of about 1 m to 4 m from the steel pipe, and is extended to an arbitrary length by being detachably connected in the pipe axis direction. It is made possible. Thereby, the casing rod 1 can respond | correspond arbitrarily to penetration depth.

  A tip cone 6 is detachably attached to the tip of the casing rod unit 1a connected to the forefront of the casing rod 1. The tip cone 6 has a conical tip portion with a tip angle of 90 ° and an outer diameter of about 45 mm from a biodegradable resin that is decomposed within a certain period by the action of metal or microorganisms, and is formed in a cylindrical shape.

  The automatic continuous striking device 2 lifts the hammer 7 having a mass of 63.5 kg free-falling from the position of 50 cm to the upper end of the casing rod 1 and the height of the hammer 7 from the upper end of the casing rod 1 to a position of 50 cm in height. In addition, the amount of penetration of the casing rod 1 by hitting the hammer 8 with the driving device 8 that automatically and repeatedly drops freely from the position of 50 cm to the upper end of the casing rod 1, that is, the amount of penetration of the tip cone 6 is 20 cm. The counter 9 is configured to automatically record the number of hits for each.

  And the condition of the ground into which the casing rod 1 has penetrated can be estimated from the penetration condition of the tip cone 6 every 20 cm, etc., thereby creating a columnar diagram (geological sectional view) as shown in FIG. Is possible.

  FIG. 4 shows that the hammer 7 is automatically dropped freely from the position of 50 cm in height to the upper end of the casing rod 1 and the number of hits of the hammer 7 required for the tip cone 6 to penetrate 20 cm is counted. Is a value recorded as the number of hits (Nd).

  The number of hits (Nd) after correction can be handled in the same manner as the N value of the standard penetration test. Further, the number of hits (Nd) can be obtained by correcting using the following equation.

Nd = Ndm-NmaNtle = Nd-0.00041Mv
here,
Nd: Corrected number of hits
Ndm: Number of hits measured
Nmantle: Number of hits equivalent to peripheral friction
Mv: Rotational torque (N · cm)

  Torque measurement for correcting circumferential friction is performed by the following method. When the value of Ndm exceeds 5 times, the casing rod 1 is rotated twice with a torque wrench for every 20 cm of penetration, and the maximum torque (Mv) at that time is measured.

  When the value of Ndm is 5 times or less, the maximum torque (Mv) is not measured (Mv = 0) only by rotating the rod twice when the casing rod unit 1a is connected.

  The drive device 8 is configured to lift the hammer 7 to a position with a height of 50 cm and lift it to a free position, or lift it with a winch to a position with a height of 50 cm and let it fall freely.

  The bundling injection tube 5 is formed by bundling a plurality of injection thin tubes 10 in parallel in the tube axis direction, and is continuously inserted to the tip in the tube axis direction in the casing rod 1. The rod 1 is held at a substantially central portion by a plurality of spacers 11.

  The spacer 11 includes a ring portion 11a through which the bundling injection tube 5 passes and a plurality of arm portions 11b protruding radially from the ring portion 11a, and is integrally formed from metal or hard wood.

  The injection thin tube 10 is formed of a plurality of injection thin tube units 10a, and the injection thin tube unit 10a is formed in the same length of about 1 to 4 m from a steel tube or a hard resin tube in the same manner as the casing rod unit 1a. They are bundled together in the tube axis direction. And it is formed so that it can be extended to any length by detachably connecting in the tube axis direction.

Further, the tip discharge ports 10b of the injection tube unit 10a connected to the forefront of each injection tube 10 are arranged at regular intervals in the tube axis direction, whereby the ground around the bundle injection tube 5 is obtained. On the other hand, the injection material sent from the ground is simultaneously injected into a plurality of layers.
On the other hand, the upper end side of each injection thin tube 10 is detachably connected to an injection installed on the ground and a liquid supply tube 13 extending from the injection material production plant 12 of the management unit 21.

  When the injection thin tubes 10 are arranged at a plurality of points, the injection thin tubes 10 are connected to each other via the liquid supply tube 13 and are connected to the liquid supply tube 13 via the flow path conversion valve 17. (FIGS. 5 (a) to (c)).

  The spacer 11 is not necessarily required, and a single injection tube may be installed instead of the bundled injection tube composed of a plurality of injection thin tubes 10a. Further, these injection pipes may be inserted into the casing rod 1 after the casing rod 1 has penetrated to the deepest depth.

  Next, the construction procedure of the ground improvement method using the ground improvement device shown in FIGS.

  (1) First, the casing rod unit 1a connected to the forefront of the casing rod 1 is set vertically under the automatic continuous striking device 2.

  In addition, an injection thin tube unit 10a connected to the foremost end of the bundled injection tube 5 is inserted into the casing rod unit 1a, and a plurality of spacers 11 are set at a substantially central portion in the casing rod unit 1a. In this case, the upper end portion of the injection thin tube unit 10a is positioned below the upper end surface of the casing rod unit 1a. The injection thin tube 10 may be inserted into the casing rod after the casing rod 1 has penetrated into the ground.

  (2) Next, the driving device 8 is actuated to repeatedly drop the hammer 7 on the upper end of the casing rod 1 to freely drop the casing rod 1 (tip cone 6) together with the thin tube unit 10a in the casing rod 1 into the ground. The counter 9 records the number of hits per 20 cm of penetration of the casing rod 1 (tip cone 6).

  (3) When the casing rod 1 (the most advanced casing rod unit 1a) has penetrated to a certain depth, the casing rod unit 1a and the thin tube unit 10a are newly connected to each other, the drive device 8 is actuated again, and the hammer 7 is moved. By repeatedly dropping naturally, the casing rod 1 (tip cone 6) penetrates into the ground together with the thin tube unit 10a in the casing rod 1, and the number of hits per 20 cm of penetration of the casing rod 1 (tip cone 6) is determined. Record by counter 9.

  In this way, the casing rod 1 is continuously penetrated into the ground, and the counter 9 records the number of hits by the hammer 7 for every 20 cm of penetration of the tip cone 6. Then, the ground situation is estimated from the penetration situation of the casing rod 1, that is, the tip cone 6 every 20 cm, and a columnar diagram (geological sectional view) as shown in FIG. 4 is created.

  (4) After the casing rod 1 has been penetrated to a predetermined depth together with the bundling injection tube 5, then from the ground through one of the injection thin tubes 10 or through the gap between the casing rod 1 and the injection tube thin tube 10a. The casing rod 1 is filled with the sealing material b by injecting the sealing material b into the casing rod 1.

  In this case, a low-strength sealing material made of, for example, a cement-based or clay-based slurry can be used as the sealing material b.

  (5) Next, the casing rod 1 is pulled out leaving the binding injection pipe 5 in the ground. For pulling out the casing rod 1, an existing rod pulling device is used, and the casing rod 1 is pulled out before the sealing material b is cured.

  The tip cone 6 can be separated from the tip of the casing rod 1 and left in the ground by increasing the filling pressure of the sealing material b.

  (6) When the casing rod 1 is completely pulled out, the injection material is fed into the ground from the injection material manufacturing plant 12 on the ground through a plurality of injection thin tubes 10 that form the bundle injection tube 5, and in the ground around the bundle injection tube 5. Inject the injection material into At that time, it is possible to inject the optimal amount and the optimal mixture of the injection material while confirming the ground condition from the columnar diagram shown in FIG.

  Moreover, the hole formed by pulling out the casing rod 1 is not filled with the sealing material b so that the hole wall does not collapse.

  Selection of these injection tubes, injection depth, injection amount, injection speed switching, ground displacement measurement, injection control, and injection switching are all instructed and controlled by the injection and management plant 19.

  5 (a) and 5 (b) show another embodiment of the present invention, and FIG. 5 (a) shows that the ground improvement devices 14 shown in FIGS. 1 and 2 are arranged at a plurality of points in the ground improvement area. At the same time, the injection pipe 10 of each place improvement device 14 penetrates into the ground, and the injection pipe 10 at each injection point is connected to the injection material production plant 12 through an injection pump, a pressure / flow rate detector 19 and a liquid supply pipe 13. .

  These are collectively controlled by the controller 15 so that ground investigation, boring and ground injection at a plurality of injection points can be performed simultaneously or at one or a plurality of injection points.

  In addition, a flow path conversion electromagnetic valve 17 is installed in each of the liquid supply pipes 13 communicating with the injection pipe 10 of the local board improvement device 14, and each flow path conversion electromagnetic valve 17 is collectively controlled by the controller 15.

  Then, when an instruction is given from the controller 15 via the electric signal circuit 16 at a certain injection point, the flow path conversion electromagnetic valve 17 is activated, and the flow path conversion electromagnetic valve 17 at the injection point Xi is connected to the injection pipe 10 in the ground. The flow path conversion electromagnetic valve 17 from the injection point X1 to Xi−1 opens only in the direction of the injection point Xi.

  Therefore, when a predetermined injection amount is injected into the injection pipe 10 at the injection point Xi or the injection pressure rises above the predetermined pressure, the flow path conversion electromagnetic valve 17 is similarly operated to send the injection liquid to other injection points. Thus, the ground can be improved continuously by injecting into a plurality of injection points while changing the injection point. For example, when one flow path conversion electromagnetic valve 17 is opened and the other flow path conversion electromagnetic valve 17 is closed, the injection liquid is injected into the ground only from a predetermined injection pipe 10.

  Of course, the flow path converting electromagnetic valve 17 may be configured to operate manually. However, the lifeline can be used even in a limited work space as long as it is configured to operate when instructed through a telegraph circuit from the management center. However, liquefaction countermeasures can be implemented.

  In addition, a plurality of ground displacement sensors 18 are arranged at predetermined positions, and the various ground displacement sensors 18 are collectively managed by the controller 15. Then, the ground displacement sensor 18 is used to monitor through the controller 15 so as not to cause damage to the ground structure and underground buried objects. When an abnormal ground displacement is observed at a certain injection point, the injection at the injection point is stopped. Therefore, the liquefaction prevention injection can be easily performed from around the structure by switching the injection to another injection point.

  Each flow path conversion electromagnetic valve 17 is a three-way cock, and is equipped with a water washing tube, which is also managed by the controller 15 and can be washed immediately after the injection from the predetermined three-way cock is completed. The road can always be injected at a predetermined injection point.

  In addition, according to the embodiment shown in FIG. 5 (a), the liquefaction countermeasure work is particularly efficiently and reliably performed in an area where a single land is divided into a plurality of areas and a detached house is built in each section. be able to.

  In the figure, reference numerals X1, X2, X5, X6, X2, X3, X4, X5, X4, Xn, Xi, X5, X5, X6, X7, Xi are respectively detached houses A1, A2, Ai, The injection point arranged so as to surround An is shown.

  The injection points may be arranged at intervals so that the solidified support formed by hardening the ground by injection of the injection material is continuous, but as described later, a laying structure such as a gas pipe May be installed at intervals so as to be able to support (see FIG. 7).

The ground improvement device 14 at each injection point may be installed vertically on the ground, may be installed obliquely under the foundation of a detached house, and may be used in combination with vertical installation and diagonal installation.
Further, there may be a plurality of liquid supply paths to each injection point by the liquid supply pipe 13. Further, the injection at each injection point is collectively controlled by the injection and management plant 21.

  In this way, the liquefaction countermeasures for the entire detached residential area can be performed collectively, and the ground improvement of the entire residential area can be easily and economically performed. In addition, the ground can be improved without hindering the living environment of the residential area.

  Here, houses A1, A2, Ai, An are examples of detached houses, but they may be continuous roads or airport runways, etc. An injection line may be formed, and a solidified body may be continuously formed on the injection line. In addition, an injection line means the line of the liquid feeding pipe | tube which makes injection pipes continuous.

  Further, according to the embodiment shown in FIG. 5 (b), buried pipes and cables such as common grooves, subways, gas pipes, water and sewage pipes, telegraph telephone lines, or linear lifelines such as roads and railways. Liquefaction countermeasures can be performed very efficiently and reliably. FIG. 5 (b) shows an example in which the injection line is arranged along the lifeline.

  Of course, even in the case of ground improvement over a wide range in a plane, continuous ground improvement can be performed by combining line arrangements as shown in FIG. 5 (a).

  That is, using the ground improvement device 14 shown in FIGS. 1 and 2, the injection pipes are arranged at regular intervals along these facilities on the ground where the laying pipes 20 such as pipelines and water and sewage pipes are laid. To do. Of course, in FIG. 5, the injection tube may not be an injection tube using the ground improvement apparatus shown in FIGS. 1 and 2, and any injection tube may be used.

  Further, the local ground improvement device 14 is connected to the injection material manufacturing plant 12 via an injection pump, a pressure / flow rate detector 19 and a liquid feed pipe 13, and the local ground improvement device 14 is collectively controlled by the controller 15.

  With this arrangement, ground investigation, boring and ground injection at multiple injection points can be performed at the same time or for each injection point, depending on the injection volume, injection pressure, and ground displacement conditions at each injection point. An injection can be performed.

  In addition, by arranging the flow path conversion electromagnetic valve 17 and the ground displacement sensor 18, the ground displacement due to injection is applied to the residential area where detached houses are densely populated, and the ground where gas pipes and water and sewage pipes are laid. The liquefaction prevention injection can be performed very simply and safely without destroying the building or the laying structure.

  In addition, a plurality of ground improvement devices 14 are arranged at regular intervals along the laying pipes 20 such as gas pipes and water and sewage pipes, and the injection pipes 10 of the local board improvement devices 14 are arranged linearly along the laying pipes 20. By using the minimum pipe work area without moving the pouring work point, the ground can be improved while operating the lifeline, by connecting with the liquid feed pipe 13 and arranging the pouring and management plant 21. Can do.

  FIG. 5 (c) shows a specific example using the flow path conversion electromagnetic valve 17. In the figure, when the injection is continuously performed while sequentially moving the injection point to the injection points Xi−1, Xi, Xi + 1,..., The flow paths are converted in three directions from the injection and management plant 21 through the electric signal circuit 16. The electromagnetic valve 17 that can be used is instructed to shut off the flow path to the injection pipe 10a of the three-way cock up to Xi−1 and release the flow path to Xi.

  At the injection point Xi, the flow path to the three-way cock Xi + 1 is blocked, and the flow path only to the injection pipe 10a at the injection point Xi is released. When the predetermined injection amount from the injection pipe 10a at the injection point xi is over, the flow path of the injection pipe 10a at the injection point Xi is blocked, the flow path to Xi + 1 is released, and the flow path to Xi + 2 is blocked. .

  In this way, the injection can be performed continuously. Since the injection amount and injection pressure of injection from each injection port 10b can be grasped by the injection amount and injection plant 21 for each location, when the predetermined injection is completed or the injection pressure rises excessively, the ground When abnormal information from the displacement sensor 18 is transmitted to the injection amount and the injection plant 21, the electromagnetic valve is instructed to shut off the electromagnetic valve 10a of Xi, and the injection liquid is sent to the injection point 4i + 1.

  FIG. 6 is a cross-sectional view showing a specific example of an embodiment of the present invention. In the figure, reference numeral 22 is a seal grout, L1 is a coarse sand layer, and L2 is a fine sand layer, both of which are expected to be liquefied.

  The injection solution is a water glass silica solution, a silica sol solution from which alkali is removed by mixing water glass and acid, a colloid solution by ion exchange method, ion exchange membrane method, metal silica method, colloid and water glass, or colloid. A mixture of water, water glass, acid and salt, a microbubble solution containing fine particles of several μm to 100 μm, a silica solution containing microbubbles, a suspension of clay, cement, slag, etc. or a silica solution and a suspension Any of these liquid mixtures or these may be used in combination.

  Of these, application is particularly effective by combining a suspension containing bentonite as an active ingredient, or a mixture of bentonite and a silica solution, and microbubbles or gas.

  For example, injecting bentonite or a mixture of bentonite and microbubbles, or a mixture of these with silica into the coarse sand layer L1, and injecting air into the fine sand layer L2 with microbubble liquid or a compressor will prevent liquefaction. As effective and economical.

  In particular, the microbubble liquid is a bubble mixed liquid of several μm to several tens of μm, and it is considered that the ground can be desaturated by injecting it under the groundwater surface to prevent liquefaction. However, there is a problem that the effect is difficult to sustain because it is washed away by groundwater flow or deviates to the ground surface.

  Moreover, since the injection of gas is easy to escape to the ground surface immediately, it is a problem to keep all in the ground for a long time.

  The present invention, for example, by injecting a grout containing bentonite as an active ingredient into the coarse sand layer L1 near the ground surface and injecting a grout containing microbubbles as an active ingredient into the fine sand layer L2 below it, for example. From the water tightness, electrochemical adsorbability and adhesiveness, it is possible to obtain the effect of preventing liquefaction by adsorbing the microbubbles so that the microbubbles are not lost for a long time due to the flow of groundwater or the like.

  Further, if air is injected below the bentonite layer using a compressor, it is possible to prevent the air from deviating to the ground surface due to the blocking effect of the bentonite layer. Of course, silica-based grout may be used instead of the bentonite, or a mixed solution of silica solution and bubbles may be used.

  In addition, as shown in FIG. 8 (a), by surrounding the structure 24 with an injection liquid containing bentonite as an active ingredient to form a consolidated wall 25, the ground immediately below the structure 24 is enclosed, By injecting a bubble-containing liquid or air into the interior, the interior can be desaturated and gas can be prevented from escaping to the periphery, thereby preventing liquefaction.

  Further, as shown in FIG. 8 (b), the periphery of the structure 24 is filled with an injection liquid containing bentonite as an active ingredient to form a consolidated wall 25, and further, the solid surface is directly below the structure 24. Enclose the ground directly under the structure 24 by using the same solidified board 27 as the connecting wall 25, inject air bubbles and liquid into the interior, desaturate the interior, and gas escapes to the surroundings. It can also prevent liquefaction.

  In particular, bentonite is excellent in long-term effect and economy by adsorbing and holding gas particles due to its electrochemical characteristics.

  In the above, since the particle size of bentonite is smaller than the particle size of bubbles, it is possible to prevent bubbles from being lost. Of course, an acidic to weakly alkaline bentonite silica solution composed of a mixture of bentonite and water glass with a reactant or a mixture of bentonite, water glass and acid is economical, water-tight and watertight. When microbubbles or gas is injected into the ground into which the liquid mixture with the microbubbles or the suspension thereof is injected, the escape of microbubbles or bubbles can be prevented, and the gas can be included in the ground for a long period of time.

  Of course, as shown in FIG. 8 (b), a solidified wall 24 made of silica-based grout is formed along a linear injection line, and via an injection pipe 26 in which bubbles or gas are obliquely installed. It is also possible to prevent liquefaction by desaturating the interior by injecting in this manner.

  The ground injection as a countermeasure against liquefaction does not necessarily have to be performed over the entire length of the laying pipe such as a gas pipe, a sewage pipe, and a water pipe. In the case of these laying pipes, for example, as shown in FIG. 7, by injecting the ground into each joint part (connection part) 22 between the laying pipes 20 that are easily liquefied during an earthquake, A consolidated support body 23 that supports the joint portion 22 of the laying pipe 20 may be formed.

  Further, the injection line may be arranged in a zigzag manner with the laying pipe interposed therebetween, or may be arranged on both sides of the laying pipe.

  In this way, the laying pipe 20 subjected to the liquefaction countermeasure work is supported by the solidified support 23 in the joint portion 22 of each laying pipe 20 even if liquefaction occurs in the surrounding ground. By having a certain elasticity, a certain degree of deflection occurs but does not lead to destruction.

  Of course, the solid support 23 may be formed for each joint portion 22 or may be formed at intervals so as not to cause breakage although the laying tube 20 is bent. This is the same in a detached residential area as illustrated in FIG. A plurality of injection lines may be connected to one injection and management plant.

  INDUSTRIAL APPLICABILITY The present invention can efficiently and easily carry out liquefaction countermeasures and ground improvement of grounds with lifelines such as condominiums, gas pipes, water pipes, and sewage pipes in which detached houses are densely built.

1 Casing rod, 1a Casing rod unit,
2 Automatic continuous striking device, 3 mast, 4 guides, 5 bundling injection tube, 6 tip cone, 7 hammer, 8 drive device, 9 counter,
10 Injection capillary, 10a Injection capillary unit 11 Spacer
11a Ring part, 11b Arm part, 12 Injection material production plant
13 liquid supply pipe, 14 ground improvement device, 15 controller,
16 electric signal circuit, 17 flow path conversion electromagnetic valve (circuit conversion device),
18 Ground displacement sensor (ground displacement measuring device),
19 Infusion pump and pressure / flow rate detector, 20 laying pipe
21 Injection and control plant, 22 Pipe joints, 23 Consolidation support
24 structures, 25 consolidation walls, 26 injection tubes, 27 consolidation machines.
X1, X2, X3, X4, X5, X6, X7, Xi, Xn injection point,
A1, A2, Ai, An Detached house (structure)

Claims (4)

  A casing rod for drilling, an injection pipe installed in the casing rod and penetrating into the ground together with the casing rod, and the casing rod penetrating into the ground together with the injection pipe by continuous impact by the natural fall of a hammer In the ground improvement device comprising a striking device and a counter for recording the number of times the casing rod is struck by a certain amount of penetration by the hammer, the casing rod is pulled out after penetrating into the ground, and the casing rod is A ground improvement device characterized by being configured so that an injection material is discharged from the injection pipe into the ground after being pulled out.   2. The ground improvement device according to claim 1, wherein the injection tube is a bundling injection tube configured by bundling one injection thin tube or a plurality of injection thin tubes in parallel in the tube axis direction. Improved device. 3. The ground improvement method using the ground improvement device according to claim 1 or 2, wherein a casing rod for drilling with a built-in injection pipe is penetrated into the ground together with the injection pipe by continuous hammering, and the casing rod is fixed by the hammer. Recording the number of hits for each penetration amount, leaving the injection tube in the ground, pulling out the casing rod, and injecting the injection material into the ground after pulling out the casing rod through the injection tube A ground improvement method that is characteristic. 3. The ground improvement method using the ground improvement device according to claim 1 or 2, wherein injection pipes are respectively arranged at a plurality of injection points, and the injection pipes and pressure / flow rate detectors are connected to the injection material manufacturing plant. In addition, by connecting through the liquid supply pipe and collectively controlling them by the controller, the ground injection at a plurality of injection points is performed simultaneously or by selecting one or a plurality of injection points, and at each injection point, A casing rod for drilling with a built-in injection pipe penetrates into the ground together with the injection pipe by hammering continuously, records the number of times the casing rod is struck by a fixed amount of penetration by the hammer, and puts the injection pipe into the ground. Pulling out the casing rod and leaving the pouring material through the pouring pipe in the ground after pulling out the casing rod Ground improvement method, characterized by injection.

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