JP2017025530A - Ground bearing force increasing injection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase foundation-under ground bearing force of a structure by constructing a compaction strengthening area in the ground, by patrolling and injecting by switching at a multipoint interval to respective chemical injection rods, by penetrating up to a stable ground layer by directly adding external force to the chemical injection rods in a plurality of places, for injecting an injection material into the structure foundation-under ground.SOLUTION: An injection point P is arranged in a plurality of places at a predetermined interval in an aboveground part to the building foundation-under ground G, and when penetrating a chemical injection rod 10 in the ground by directly adding thrust at these injection points, the chemical injection rod is installed by determining the penetration depth by estimating a compaction degree of the ground G based on a shift of a propulsion load, and an injection material is respectively supplied by a very small quantity to the chemical injection rod 10 by multipoint injection for supplying by successively switching an injection place at a predetermined time interval via a distribution switching valve by the setting by control means from a chemical supply device, and a compaction strengthening part Q of soil is formed by detaining in the ground in the vicinity of a discharge part of the chemical injection rod 10.SELECTED DRAWING: Figure 2

Description

  The present invention circulates and repeatedly injects the injection material little by little at injection points arranged at a plurality of locations in the lower ground of the existing structure foundation, forms a consolidation strengthening zone in the lower part of the ground, and normalizes the existing structure. The present invention relates to a ground support capacity increasing method capable of stably supporting in a stable state.

  Conventionally, as a technique for improving the supporting ground of an existing structure, a method of injecting a self-hardening chemical into the ground for the purpose of reducing water permeability or increasing adhesive force has been widely adopted. Various methods have already been proposed and implemented as improvement means. Most of them are short-lived grouting with short gel time or slow-growing grouting with long gel time is injected into the ground using an injection tube, and the injected material is combined with the soil of the ground to form a solidified body and surroundings. There is a known method for strengthening the ground by applying a pressing force to the soil and increasing the pressure density.

  For example, there is a phenomenon that the structure sinks due to ground deformation caused by an earthquake or excavation work in the vicinity. As a method of restoring a tilted structure due to such uneven settlement, a chemical solution is injected into the ground below the foundation of the tilted structure to form a consolidated body. Patent Document 1 and the like disclose a technique for increasing the density and taking a reaction force on the solidified body and injecting the whole structure to restore the structure when the chemical solution is injected.

  In addition, with the aim of improving the ground, a large number of chemical solution injection pipes are arranged at multiple points, and each of these chemical solution injection pipes is supplied with an injection chemical solution material and simultaneously or selectively injected into the ground, so that the injection chemical solution material is grounded. Patent Documents 2 and 3 disclose a technique for improving the ground by infiltrating inside and forming a consolidated body.

  Furthermore, as a means for improving soft ground, a method for strengthening the ground by creating a columnar ground improvement part by injecting and injecting a chemical solution material while excavating the ground is known, for example, from Patent Document 4 and the like.

  However, in the conventional ground improvement method, for example, in the method according to Patent Document 1, it is recognized that the restoration of the structure by the non-uniform settlement is effective, and many structures are restored by the non-uniform settlement. Because the main purpose is to improve the target section, the chemical solution supply to the chemical solution injection pipes installed at multiple locations in the surface layer of the ground is switched at the required intervals to inject intermittently, so-called multipoint interval injection is performed, Since it is a method of lifting the structure of the ground part using the injection reaction force while maintaining a balance by restricting the amount of injection once relatively, the chemical solution injection remains at the surface layer part of the ground. Therefore, it cannot be said that it is sufficient when improving to the deep layer, for example, improving soft ground.

  In addition, in the methods known from Patent Documents 2 and 3 in which multi-point injection is performed simultaneously or selectively, chemical solutions are injected all at once by a chemical solution injection tube installed at a plurality of locations and inserted to a required depth position of the ground. Therefore, even in this construction method, the consolidation of the soil is enhanced by the permeation and diffusion of the chemical material at a limited depth in the ground, and a large number of high-pressure pumps are required, resulting in an increase in the size of related equipment and increase in equipment costs and operating costs. There is a problem.

  Furthermore, in the ground improvement technology of the excavation injection method as known in Patent Document 4, a columnar improvement portion is created in the ground, and the drilling depth can be freely obtained, so that the columnar shape extends deep into the formation. The improved part is created and effective for strengthening the ground, but the construction becomes large, and the improved part cannot be created at multiple places at once, and it is necessary to introduce relatively large equipment machines for construction, There are problems such as requiring a lot of construction costs.

Japanese Patent No. 3126896 Japanese Patent No. 4667293 JP 2003-232030 A JP 2008-208620 A

  In the present invention, when a chemical injection rod that has a propulsion function and can estimate the geology at the propulsion depth is arranged at a plurality of locations in the target ground area, the chemical injection rod is directly penetrated to the stable formation, and each chemical injection rod The liquid supply is switched in a short time in the order selected at a predetermined interval, and cyclic injection is performed. After the predetermined amount injection operation, the step of stepping up the chemical injection rod is repeated, and the soil consolidation strengthening region by chemical injection into the ground An object of the present invention is to provide a ground support strength enhancing injection method capable of enhancing the ground support force under the foundation of the structure up to the deep layer corresponding to the state of the formation.

In order to achieve the above-mentioned object,
Injecting points at multiple locations at predetermined intervals on the ground base of the structure foundation foundation board, and applying a thrust directly to the chemical injection rod equipped with a propulsion function at these injection points, Based on the displacement, the pressure density of the ground is estimated and the penetration depth is determined and installed, and the chemical liquid material is set to the chemical liquid injection rod from the chemical liquid supply device by the control means at a predetermined time interval through the supply switching means. By the multi-point injection in which the injection points are sequentially switched and supplied, a very small amount is supplied and stays in the ground in the vicinity of the discharge portion of the chemical injection rod to form a consolidation consolidation region of the soil.

  In the above invention, the chemical injection rod installed at the injection point has a double tube structure, a cone is coaxially attached to the tip of the outer tube, and a plurality of outer tubes of a predetermined length are sequentially connected. Using a propulsion means that directly applies a propulsive force in the axial direction of the outer pipe so that it reaches a predetermined depth, it is successively added and pushed into the ground to a predetermined depth, and a tube is used as the inner pipe, and the rear end It is preferable to attach a head provided with a liquid supply connection part communicating with the inside of the outer pipe and the inner pipe to the part so that the injection material is supplied.

  The chemical injection rod installed at the injection point stops the penetration operation in a state where it is determined that the applied driving force has reached a state exceeding a predetermined load, and performs the chemical injection operation. Features.

  Further, in the present invention, the chemical injection at the injection point by the chemical injection rod is performed by sequentially switching a plurality of injection points at a necessary time and injecting a small amount in a short injection time. When the reinforcement region is formed around the injection point by repeating this operation so as to remain in the surrounding ground, the chemical solution injection rod is stepped up by an amount corresponding to the vertical direction of the reinforcement region formation, and the operation is repeated. It is characterized in that a chemical liquid material injected by reducing the amount of one injection by multi-point injection stays around the injection point to form a strengthened region laminated in the vertical direction.

  In the present invention, the penetration propulsion means added for penetration of the chemical solution injection rod includes a weight method in which an outer tube is gripped and thrust is applied, a hydraulic drive method, a striking method in which external force is applied to the top of the rod (monken), rotation A method selected from among penetration methods can be adopted.

  According to the present invention, the chemical injection rod is directly penetrated into the ground as it is, and the pressure density inside the ground at the penetration point (infusion point) is directly sensed by the penetration load, and the appropriate penetration depth is directly detected. The liquid material can be injected with a deep penetration depth. Therefore, it is possible to form a wide reinforced area by consolidating the soft layer with the stable layer in the ground and the strengthening range by injecting the chemical material at the upper part, and appropriate and more effective structure support without excessive injection The ground can be strengthened.

  In addition, according to the present invention, by injecting the injection material so that the injection material stays around the discharge portion of the injection material by the chemical injection rod, without causing excessive injection and preventing the injection material from running away or abnormally rising, It becomes possible to increase the pressure density of the ground by reducing the amount of injection, and the effect of strengthening the supporting force of the structure foundation base plate by the chemical solution injection can be achieved economically.

It is a schematic diagram showing typically one embodiment of the ground support power reinforcement injection method of the present invention. It is a schematic diagram which represents one embodiment of the ground supporting force reinforcement | strengthening injection method by this invention compared with a ground penetration pressure distribution map (block diagram). It is a figure showing an example of an injection | pouring pipe | tube, Comprising: The figure (b) which shows the pipe body of the intermediate part connected with the figure (a) which shows the front-end | tip part of an injection pipe, and the partial sectional view (c) showing an injection | pouring head part is there. It is a figure which shows an example of the penetration promotion means used for penetration of an injection pipe. It is a figure which represents typically the chemical | medical solution supply apparatus used for implementation of the ground supporting force reinforcement | strengthening injection method of this invention, and its installation condition.

  Next, an embodiment of the ground bearing capacity enhancing injection method of the present invention will be described with reference to the drawings.

  In the ground supporting capacity increasing injection method according to the present invention, the chemical solution injection rod 10 is installed at the injection points P distributed to a plurality of locations with respect to the foundation base plate G on which the load of the existing structure A acts. The operation of switching and injecting the injection point P one by one at a preset time interval in small increments is repeated, and the ground G is injected by injecting the injection material corresponding to the state in which the loading load by the structure A acts. Force consolidation. The chemical injection rod 10 used in this injection operation is directly penetrated into the ground G, and at the same time, the geological investigation is performed at the time of the penetration operation, and the injection material is injected within the range of the penetration depth corresponding to the consolidated state of the formation, By avoiding excessive injection, it is possible to implement a rational and economical support for the ground.

  And in the ground supporting force reinforcement injection method of the present invention, the injection amount of the injection material is sequentially switched according to the state of the formation measured in the process of penetrating the chemical injection rod 10 installed at the injection point P to a predetermined depth. Like that. That is, when stepping up and injecting, the injection amount of the injection material is increased in the formation portion where the pressure density is low, and conversely, the injection amount of the injection material is reduced in the formation portion where the pressure density is high. . In some cases, the injection is not performed in the formation portion having a high pressure density (see FIG. 2). By using the injection method according to the distribution of the formation in this way, the injection material can be rationally injected, the pressure density of the target ground can be improved generally without using excessive injection material, and the economic effect is enhanced. Can be obtained.

  In this embodiment, a chemical solution injection rod 10 (hereinafter simply referred to as “injection tube 10”) installed at a plurality of injection points P distributed at predetermined intervals (described later) to the target ground G is shown in FIG. As illustrated, a double tube structure is employed. As the outer tube 11 of the injection tube 10, a metal tube having a predetermined diameter and having a predetermined length is a joint 14 having a known structure (for example, an external screw 14 a is provided at one end of the external tube 11, and an external screw 14 b is provided at the other end. The screw joint structure that is provided and sequentially connected by screw connection is used. A conical head member 13 (corresponding to the “cone” of the present invention) is attached to the tip portion with the tip end first, and the mounting shaft portion 13a of the head member 13 and the inner diameter of the outer tube end In the fitting portion, there are radially provided injection material discharge ports 15 at a plurality of locations on the peripheral surface of the outer tube 11, and the outer tube 11 is sequentially connected, and the injection material supply pipe connection ports 17 and 18 are connected at the final end. The provided head 16 is connected. In addition, the tube which consists of a flexible material is combined as the inner tube | pipe 12 (it can be made to respond | correspond to the penetration length of an outer tube | pipe).

  When performing the penetration operation at the injection point P, the injection pipe 10 having such a configuration uses, for example, the penetration propulsion means 20 similar to the Swedish sounding test apparatus, and uses the injection pipe 10 provided with the leading member 13 as a base. It penetrates into the ground G. As shown in FIG. 4 as an example, the penetration propulsion means 20 includes a main body frame 21 that can be moved and is upright when in use, and a lifting frame that is supported so as to be slidable vertically along the front surface of the main body frame 21. 22, a loading board 24 incorporated in the lifting frame 22 and capable of mounting a plurality of weights 23 for applying a load at the time of penetration; a clamp 25 provided on the upper surface of the lifting frame 22 for holding the injection tube 10; A wire 26 for lifting the frame 22 and a winch 27 are provided. However, the penetration propulsion means is not limited to the above example such as a hydraulic jack or a mechanical jack as a drive source. In the figure, reference numeral 28 denotes a guide sheave provided at the top of the main body frame, and 21a denotes a wheel that can be moved by being grounded when the main body frame 21 is tilted during the transfer.

  In the penetration operation of the injection tube 10, a selection value similar to the reference for the penetration test is prepared in advance, the injection tube 10 is gripped by the clamp 25 on the lifting frame 22 in the penetration propulsion means 20, and a predetermined value is applied to the loading board 24. The weight 23 is mounted and pushed vertically with the load. Then, the injection tube 10 is guided to the front surface of the main body frame 21 together with the lifting frame 22 to which the clamp 25 is attached, and is then inserted. During the penetration operation, every time the injection tube 10 is penetrated by a predetermined length, the grip by the clamp 25 is released, the lifting frame 22 is lifted by a winch 27, and the injection tube 10 is again gripped by the clamp 25. The operation of pushing in with the load of the weight 23 is repeated. The winch 27 loosens the wire during the penetration operation.

  At the time of the penetration operation, data on the penetration of the injection pipe 10 after the surface layer portion of the ground G is recorded to estimate the geology. In this case, the penetration operation is stopped when it is sensed that the formation has reached a high pressure density formation in the deep layer based on the obtained data, and the installation of the injection tube 10 is completed. Therefore, since the penetration depth of the injection tube 10 at each injection point P is not constant, it is set to a depth considered appropriate. When the penetration installation of the injection pipe 10 is finished, the penetration promotion means 20 is removed and moved to the next injection point, and the injection pipe is installed at the position in the above manner.

  The chemical liquid supply device 30 for supplying the injection material to each of the injection tubes 10 prepares, for example, a water glass-based injection material (A liquid) and a cement-based injection material (B liquid), and these A liquid and B liquid respectively. A pump that can be supplied separately by the liquid feed high-pressure pumps 31A and 31B is used.

  In order to supply the injection material to the injection pipes 10 installed at the respective injection points P, the chemical solution supply device 30 distributes the supply pipes 32A and 32B provided to correspond to the injection pipes 10 respectively. Connected by pipes 33A and 33B branched via a switching valve 34, and switched by selecting an injection point P to be supplied at a set injection time in accordance with a control command set by a control panel 35 attached to the chemical liquid supply device 30. The injection time of the chemical liquid material is shortened so that it can be sequentially and repeatedly injected in small amounts (see FIG. 5).

  The injection material (A liquid and B liquid) supplied in the above-mentioned chemical liquid supply apparatus 30 is prepared separately. As the injection material used here, one having a long solidification time, that is, a so-called slow-setting injection material is used. Further, in the control means (control panel 35) for controlling the operation of injection, the amount selected in the range of 0.6 to 4.0 liters as the one injection amount at one injection point P, the injection interval The supply stop time is set to correspond to the gelation of the injected injection material and the predetermined strength development time. When this injection material is injected into the ground from the discharge port 15 at the tip of the injection tube 10 and a required time has elapsed, the distribution switching valve 34 closes the supply of the injection material to the injection point P and the next injection point P is supplied. The distribution switching valve 34 is switched to the open state, and the injection material is supplied to the pipes 33A and 33B branched to the injection pipe 10. This operation is sequentially switched with respect to each injection tube 10, and it injects to each after circulating a predetermined number of times.

  As described above, when the injection material is supplied to the injection pipe 10 at each injection point P, all the distribution switching valves 34 assigned to the injection pipes 10 are provided in the supply pipes 32A and 32B connected in series. It is provided and is in communication. Since the terminal ends of the supply pipes 32A and 32B are closed (plugs or valves), only the distribution switching valve 34 to the injection point selected by the command of the control means is opened, and the other distribution is performed. The switching valve closes the pipes 33A and 33B branched to the injection pipe 10. Accordingly, since the supply pipes 32A and 32B are maintained at a predetermined pressure, when the injection material is supplied to each injection pipe 10, it is discharged from the injection pipe 10 into the ground at a predetermined pressure at any position. To work.

  The injection material injected into the ground through the injection pipe 10 at the injection point P in this way is very small in supply amount per time, so when discharged from the discharge portion into the ground, it is dispersed in the shape of a tree root and its surroundings. The waiting time is the time for the discharged injected material to gel and develop at a predetermined strength, and the supply of the injected material to other injection points P is sequentially switched during this waiting time. Is done.

  When the injection material is supplied again to the injection pipe 10 at the injection point P where the switching is completed once, the injection material to be discharged is discharged first, dispersed in the soil, tied, gelled and consolidated. Subsequent injection material is injected into the portion being pressed by the injection pressure and flows, flows out of the previously consolidated portion, is connected to the surrounding soil, and is distributed in branches. When this state is repeated a predetermined number of times by subsequent injections, the injection amount at one time is very small, so that it remains at the discharge peripheral portion at the injection point P without greatly expanding.

  The arrangement interval of each injection point P is estimated in consideration of conditions such as the viscosity of the injection material to be injected, the injection amount, the injection pressure and the geology, and the dispersion radius to the periphery due to the injection of the injection material at the injection point P. However, it is preferable to dispose at an interval exceeding (but not limited to) twice the dispersion radius.

  When the injection at each injection point P is repeated a predetermined number of times, the injection operation is temporarily stopped. Thus, when a predetermined amount of the injection material is injected around the discharge portion depth position of the injection pipe 10 that has been first installed in a penetrating manner, the soil consolidation strengthening portion Q (corresponding to the consolidation strengthening region of the present invention) is formed. Then, the injection pipe 10 is pulled up by a pipe pulling means (reverse operation of the penetration propulsion means 20 previously used for penetrating the injection pipe, or a separate pile remover) (step up). . When the injection tube is pulled up, the leading member 13 attached to the tip of the injection tube 10 remains in the initial stage, and the pipe body (the outer tube 11 and the inner tube 12) is pulled up.

  Next, when the injection tube 10 is stepped up by a certain size, the injection of injection material is sequentially repeated again in the manner described above. In this way, the consolidation strengthened portion Q formed in the shape of a tree root is formed in a laminated state on the upper side of the consolidation strengthened portion Q formed in the ground by the previous injection.

  Here, regarding the injection of the injection material by step-up of the injection tube 10, as illustrated in FIG. 2, a penetration pressure distribution diagram is created based on the data obtained at the time of penetration of the injection tube 10, and this penetration pressure distribution diagram. Accordingly, the injection amount of the injection material is increased in the layer h having a low pressure density. In addition, the layer H having a high pressure density is stepped up by reducing the injection amount of the injection material.

  In this way, the injection tube 10 is repeatedly stepped up and injected in the manner described above, and the consolidation strengthening portions Q and Q ′ having a capacity corresponding to the state of the formation are expanded in the vertical direction in the ground. By performing such an injection operation in parallel at each injection point P, the surrounding soil is consolidated in the lateral direction by the consolidation strengthening portions Q and Q ′ formed at the adjacent injection points P, respectively. The foundation ground board G of the building A is strengthened.

  According to the present invention, an external force is directly applied to the chemical injection rod (injection tube 10) to penetrate into the ground, and the pressure density inside the ground at the penetration point is detected from the penetration load, so that the stable formation directly The amount of injection can be increased or decreased by setting the appropriate penetration depth by sensing this and making the injection operation of the injection material corresponding to the formation. Therefore, it is possible to form a strengthened zone by consolidation by injection in the upper part of the ground together with the stable layer in the ground in the state where the load is applied by the structure, and it is an effective structure that enhances economic efficiency without excessive injection The support ground can be strengthened.

  According to the above description, it has been described that the injection pipe is penetrated into the ground using a gravity type or power pressurization type penetration propulsion means. However, a driving head is provided at the rear end (upper end at the time of penetration) of the injection pipe. It is also possible to adopt a method (monken) in which a heavy cone suspended by a pulley that is detachably attached and supported by a temporary support (for example, a tripod support) is dropped to apply impact force. It is also possible to penetrate the injection tube by rotating it.

10 Injection tube (chemical injection rod)
11 Outer tube 12 Inner tube 13 Tip member (cone)
DESCRIPTION OF SYMBOLS 15 Injection material discharge port 16 Head 20 Penetration propulsion means 22 Lifting frame 23 Weight 25 Clamp 30 Chemical solution supply device 31A, 31B Liquid feeding high pressure pump 34 Distribution switching valve A Structure G Ground Q, Q 'Consolidation strengthening part (strengthening zone)

Claims (5)

  Injecting points at multiple locations at predetermined intervals on the ground base of the structure foundation foundation board, and applying a thrust directly to the chemical injection rod equipped with a propulsion function at these injection points, Based on the displacement, the pressure density of the ground is estimated and the penetration depth is determined and installed, and the chemical liquid material is set to the chemical liquid injection rod from the chemical liquid supply device by the control means at a predetermined time interval through the supply switching means. Multi-point injection that sequentially switches the injection site, supplying a very small amount and staying in the ground near the discharge part of the chemical injection rod to form a consolidation consolidation area of the soil Injection method.   The chemical injection rod to be installed at the injection point has a double tube structure, and a cone is coaxially attached to the tip of the outer tube, and a plurality of outer tubes of a predetermined length are sequentially connected to reach a predetermined depth. Using a propulsion means that directly applies a propulsive force in the axial direction of the outer tube, the outer tube is successively added and pushed into the ground to a predetermined depth, and a tube is used as the inner tube. 2. The ground supporting force-enhancing injection method according to claim 1, wherein a head provided with a liquid supply connection portion communicating with the inside of the pipe and the inner pipe is attached so that the injection material is supplied.   The chemical injection rod installed at the injection point stops the penetration operation in a state where it is determined that the applied driving force has reached a state exceeding a predetermined load, and performs the chemical injection operation. The ground supporting capacity enhancing injection method according to claim 1 or 2,   The liquid injection at the injection point by the chemical liquid injection rod is performed by sequentially switching a plurality of injection points at a required time and injecting a small amount in a short injection time, and the injection chemical liquid material remains in the ground around the injection point. Thus, when the strengthening zone is formed around the injection point by repeating this operation, the chemical solution injection rod is stepped up by an amount corresponding to the vertical axis direction of the strengthening zone formation, and the operation is repeated, and once by multipoint injection. 2. The ground supporting force enhancing injection according to claim 1, wherein a strengthening region is formed in which a chemical material injected with a small amount of injection is stacked vertically so as to stay around the injection point. Construction method. The propulsion means added for penetration of the chemical solution injection rod includes a weight method in which an outer tube is gripped and thrust is applied, a hydraulic drive method, a rotary penetration method, or a striking method in which external force is applied to the top of the rod (Monken) The ground support capacity increasing injection method according to claim 1, wherein the selected method is adopted.

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