JP2005307694A - Pile foundation and foundation structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pile foundation and a foundation structure capable of supplementing disadvantages of the pile foundation and a direct foundation and controlling uneven settlement actively. <P>SOLUTION: This foundation structure uses the direct foundation utilizing ground reaction force to a foundation board 3 and the pile foundation utilizing support force by a pile 2. A reaction force adjusting device 4 for ensuring support force for a long time by friction force generated by oil pressure and causing slide when applying force exceeding fixed force to reduce pile supporting force is provided on the pile foundation. The reaction force adjusting device is provided with a displacement gage 45 for detecting settlement, a pressure adjusting pump 42 and a pressure distributor 43 as an oil pressure adjusting means for adjusting oil pressure, and a controller 47 as a control means for controlling the oil pressure adjusting means and adjusting oil pressure based on the result of detection of the displacement gage. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a foundation of a structure, and more particularly to a pile foundation capable of controlling unequal settlement of a structure, and a foundation structure using the pile foundation and a direct foundation in combination.

The present applicant has previously proposed a pile foundation having a reaction force adjusting device on the pile head and a foundation structure using the pile foundation and a direct foundation in combination (see Patent Document 1).
JP 2002-121752 A

  FIG. 5 shows the foundation structure shown in Patent Document 1, and supports a part of the load of the structure 1 by the supporting force by the pile 2 and directly supports the remaining load by the ground reaction force against the foundation plate 3. It is what I did. In such a structure, the proof strength and required number of piles 2 can be reduced as much as the ground reaction force can be expected, but if the ground subsidence (for example, consolidation subsidence) occurs, the ground reaction force on the foundation plate 3 can be expected. In that case, an excessive axial force exceeding the assumed support force acts on the pile 2, so there is a concern that the pile 2 may be damaged or that the structure 1 may be deformed excessively due to uneven settlement. Therefore, in the above-described foundation structure, the reaction force adjusting device 4 is provided on the pile head so as to absorb uneven settlement and prevent such a situation in advance.

  For example, as shown in FIG. 6, the reaction force adjusting device 4 extends the pile head of the pile 2 as it is to the outside of the inserted steel pipe 5 fixed to the foundation plate 3 and loosely inserts it as an extrapolated steel pipe 6, and The friction generating means 7 is interposed between them. The friction generating means 7 attaches a film 9 made of elastic rubber or the like to the outside of the tube body 8 connected to the inserted steel pipe 5 to form an oil containing portion 10, and (c) is formed outside the film 9. As shown in the figure, a slit steel pipe 12 having a large number of slits 11 is mounted, and oil is supplied to the oil storage portion 10 by an oil supply pipe 13 and the hydraulic pressure adjustment valve 14 is closed to maintain a predetermined pressure. By doing so, the membrane 9 is expanded by the oil pressure, the slit steel pipe 12 is expanded outward, and the outer surface thereof is slidably pressed against the inner surface of the extrapolated steel pipe 6.

  In such a reaction force adjusting device 4, the oil pressure in the oil accommodating portion 10 is adjusted to set the frictional force between the slit steel pipe 12 and the extrapolated steel pipe 6 to be equivalent to the long-term support force that the pile 2 should bear. Thus, the long-term support force by the pile 2 can be secured without any trouble by the friction force at all times. And if ground subsidence occurs and the ground reaction force against the base plate 3 is reduced and the load acting on the pile 2 is increased accordingly, the long-term supporting force (that is, the above frictional force) is exceeded. When an excessive load is applied to the pile 2, the sliding surface naturally slips and sinks are absorbed, thereby preventing the ground reaction force from recovering again and applying an excessive load to the pile 2. It can be done. Note that a lubricant is applied to the sliding surface so that slipping occurs promptly and reliably when subsidence occurs.

  According to the above basic structure, even if the ground strength is insufficient, it is possible to expect the ground reaction force, so it is sufficiently effective. Therefore, the required number and arrangement of the piles 2 are determined analytically so that the unequal settlement is minimized at the design time, and the piles 2 are provided with the anti-sag. It is necessary to strictly set the oil pressure of each friction generating means 7 so that the frictional force in the force adjusting device 4 is appropriate. However, it is not always easy to perform ground analysis and frictional force setting at the time of such design, and the above structure should effectively cope with unequal subsidence different from the original assumption after completion. However, there was a need for improvement in this regard.

  In view of the above circumstances, the present invention is based on the conventional pile foundation as described above and the foundation structure thereby, further improving its reliability and effectiveness, and also capable of actively controlling uneven settlement. And aims to provide a foundation structure.

  The gist of the pile foundation and foundation structure of the present invention is that the means for adjusting the oil pressure according to the unequal settlement actually generated is added to the reaction force adjusting device in the conventional pile foundation and foundation structure. To do.

  That is, the invention of claim 1 is a pile foundation that is driven or embedded in the ground or a foundation plate, and the pile head is connected to the structure so as to be relatively displaceable to support the structure, Of the first insertion body fixed to the structure, the second insertion body inserted or extrapolated into the first insertion body, and the first insertion body and the second insertion body The oil container is provided on one side, and the wall of the oil container presses the other wall surface of the first insert and the second insert by the oil pressure of the oil container, There is provided a reaction force adjusting device provided with a friction generating means for increasing the friction force at the time of insertion between the first insertion member and the second insertion member, the reaction force adjusting device comprising a foundation plate and a pile head A displacement meter that detects relative displacement with respect to the hydraulic unit, hydraulic pressure adjusting means that adjusts the hydraulic pressure in the oil storage unit, That formed by a control means for regulating the hydraulic pressure by controlling the hydraulic pressure adjusting means based on a detection result of the displacement meter is characterized in.

  According to a second aspect of the present invention, in the pile foundation of the first aspect of the invention, a lubricant is applied to the sliding surface between the first insertion body or the second insertion body and the wall surface of the oil containing portion of the friction generating means. It is characterized by being made.

  According to a third aspect of the present invention, in the pile foundation according to the first or second aspect, the friction generating means includes an oil containing portion, oil filled in the oil containing portion, and a hydraulic pressure adjusting valve for adjusting a hydraulic pressure in the oil containing portion. Thus, the wall body of the oil storage portion that contacts the wall surface of the first insertion body or the second insertion body is formed so as to be swellable by oil pressure.

  The invention of claim 4 is the pile foundation of the invention of claim 3, wherein the wall of the oil containing part is formed with a slit so that the wall is easily deformed, A stretchable film is provided to maintain liquid tightness in the oil container.

  The invention according to claim 5 is the foundation structure formed by using both the direct foundation using the ground reaction force and the pile foundation using the supporting force by the pile, and the pile foundation according to claim 1, 2, 3 or 4 It is characterized by using a pile foundation.

  According to the pile foundation of the present invention, the amount of settlement actually generated at the position of each pile is detected by a displacement meter provided in the reaction force adjustment device, and the hydraulic pressure in the reaction force adjustment device is automatically adjusted based on the detected amount of settlement. Therefore, proper pile support force can always be obtained, and even if an unexpected settlement occurs, it can be corrected at that time and can be actively controlled to prevent uneven settlement. In particular, slipping occurs promptly and reliably when subsidence occurs by applying a lubricant to the sliding surface of the friction adjusting means. Further, if the wall of the oil container is bulged as the friction generating means and the surface thereof is a sliding surface, a sufficient frictional force can be secured with a simple configuration. Furthermore, by forming a slit in the wall surface of the oil storage portion, a frictional force can be obtained reliably and adjustment thereof is facilitated.

  According to the foundation structure of the present invention, it is possible to perform active control that can correct uneven settlement by adopting the above-mentioned pile foundation, and the combined use of the above-mentioned pile foundation and the direct foundation does not provide sufficient ground strength. Therefore, it is possible to reduce the required number of piles, and therefore to provide a structure with uneven load distribution on the ground where sufficient ground strength cannot be obtained. In such a case, it is suitable for use as the basic structure.

  An embodiment of the present invention will be described with reference to FIGS. This embodiment basically uses a pile foundation that uses the supporting force of the pile 2 and a direct foundation that uses the ground reaction force to the foundation plate 3 in the same manner as the foundation structure shown in Patent Document 1, The pile head is provided with a reaction force adjusting device 4 to absorb uneven settlement.

  The reaction force adjusting device 4 in the present embodiment basically functions in the same manner as the conventional device shown in FIG. 6, but in the present embodiment, for example, the reaction force adjusting device 4 is shown in FIGS. The configuration shown in FIG. 3 or the configuration shown in FIG. 3 is employed.

  The reaction force adjusting device 4 shown in FIGS. 1 to 2 is fixed to the structure 1 by embedding an extrapolated steel pipe 21 (first insertion body) in the foundation plate 3, and the upper end of the pile 2 is The inner steel pipe 22 (second insertion body) is loosely inserted into the outer steel pipe 21 and the friction generating means 23 is provided inside the outer steel pipe 21. The friction generating means 23 is provided with a slit steel pipe 27 (shown in FIG. 6) in which a film 24 for forming an oil containing portion 25 is mounted on the inner surface side of the extrapolated steel pipe 21, and a slit 26 is formed inside the film 24. The same structure as that of the conventional slit steel pipe 12) is installed, and the oil supply pipe 28 pressurizes and supplies oil to the oil containing portion 25 to inflate the membrane 24 inward and the slit steel pipe 27 inward. As a result, by reducing the diameter of the slit steel pipe 27 as a whole, the inner surface of the slit steel pipe 27 is pressed against the outer surface of the inserted steel pipe 22 (that is, the pile head peripheral surface of the pile 2), and the desired friction is achieved. By adjusting the oil pressure in the oil containing portion 25, the sliding becomes a sliding surface and slippage occurs, and relative displacement in the vertical direction between the pile 2 and the foundation plate 3 is allowed. It is like that. A lubricant may be applied to the sliding surface as in the conventional case.

  In FIG. 2A, reference numeral 30 denotes an inspection lid bolted to the upper end of the extrapolated steel pipe 21 via a flange 31, and 32 is formed on the outer peripheral surface of the extrapolated steel pipe 21 to reinforce it. And a reinforcing rib 33 for being integrated with the base plate 3 is a spacer which is interposed between the extrapolated steel pipe 21 and the slit steel pipe 27 to form the oil storage part 25 and supports the upper and lower edges of the membrane 24. , 34 is a ring body that is bolted to the lower end portion of the extrapolated steel pipe 21 via the flange 35 to hold the slit steel pipe 27 and the spacer 33. 2 (b) is a ribbon steel plate for protecting the membrane 24. The ribbon 24 is interposed between the membrane 24 and the slit steel pipe 27 at the position of the slit 26 so that the membrane 24 is slit. It can be prevented that it gets into the inside 26 and gets damaged.

  In addition to the above, the reaction force adjusting device 4 of the present embodiment is provided with means for adjusting the oil pressure every moment according to the unequal settlement that actually occurs. That is, as shown in FIG. 1, a hydraulic pressure supply device 41 for pressurizing and supplying oil from a hydraulic pressure source 40 to each reaction force adjusting device 4 provided in each pile 2 has a hydraulic pressure adjusting means. A pressure adjusting pump 42 and a pressure distributor 43 are provided so that oil is distributed and supplied to each reaction force adjusting device 4 through each hydraulic pressure supply pipe 28, and each reaction force adjusting device. The oil pressure at 4 can be individually adjusted.

  In addition, the lid 30 mounted on the upper end of the extrapolated steel pipe 21 detects the relative displacement between the foundation plate 3 and the pile head as shown in FIG. A displacement meter 45 is provided for detecting. The displacement meter 45 detects the relative displacement of the pile 2 with respect to the foundation plate 3 by detecting the distance between the lid body 30 and the pile head plate 46 with high accuracy, and the detection result is a personal computer or the like. The controller 47 controls the pile 2 by controlling the pressure adjusting pump 42 and the pressure distributor 43 as the hydraulic adjusting means based on the detection result of each displacement meter 45. The oil pressure supplied to is adjusted according to the respective displacements. In order to perform the control as described above, the hydraulic pressure adjusting valve 48 provided in the oil supply pipe 28 is normally closed, and when the control as described above is performed, the pile 2 to be controlled is interlocked with the control. In this case, the hydraulic pressure adjustment valve 48 may be automatically opened.

  FIG. 3 shows another configuration example of the reaction force adjusting device 4. In the reaction force adjusting device 4 shown in FIGS. 1 and 2, the friction generating means 23 is provided inside the extrapolated steel pipe 21. However, in the reaction force adjusting device 4 shown in FIG. This is provided outside the inserted steel pipe 22. That is, in this case, the pile head of the pile 2 is loosely inserted into the lower end portion of the extrapolated steel pipe 21 embedded in the foundation plate 3, and the inner steel pipe 22 (second insertion body) is fixed to the pile head. The membrane 24 is attached to the outside of the inserted steel tube 22 to form the oil containing portion 25, and the slit steel tube 27 is attached to the outside of the membrane 24, and the slit steel tube 27 is bulged outward by hydraulic pressure to expand the diameter. By doing so, a desired frictional force is obtained by pressing the outer surface against the inner surface of the extrapolated steel pipe 21, and the position of the upper end portion of the interpolated steel pipe 22 is determined by the displacement meter 45 in the same manner as described above. By detecting, the relative displacement between the pile 2 and the foundation plate 3 can be detected. In addition, the code | symbol 50 replaces said reinforcement rib 32, the stud provided in the extrapolation steel pipe 21, 51 closes the clearance gap between the lower end part of the extrapolation steel pipe 21, and the surrounding surface of the pile 2 loosely inserted there. It is a sealing material for ensuring water-stopping.

  By adopting the reaction force adjusting device 4 having the configuration shown in FIG. 2 or FIG. 3, the pile foundation of this embodiment and the foundation structure using the same are shown in FIG. As described above, the entire structure 1 can be stably supported by the pile support force by the piles 2 and the ground reaction force to the foundation plate 3, but in addition, unexpected uneven settlement occurs. In such a case, it is possible to control such that the amount of subsidence there is appropriately corrected by adjusting the oil pressure based on the actual amount of subsidence detected by the displacement gauge 45 at the position of each pile 2. Therefore, it also functions as an active unequal subsidence prevention system that actively controls unequal subsidence. Specifically, for example, when uneven settlement as shown in FIG. 4B occurs, the amount of settlement at the position of each pile 2 is detected by each displacement meter 45, and based on that, the amount of displacement is calculated. It is possible to correct such unequal subsidence by increasing the oil pressure at a large position to suppress subsidence, and conversely by controlling the oil pressure at a small displacement to reduce the oil pressure. Is possible. In this case, it is necessary to set the pile strength of each pile 2 on the assumption that such control is performed, and if necessary, if an upper limit of oil pressure is set to protect the pile good.

  Although the embodiment of the present invention has been described above, the present invention can be appropriately changed in design as long as the oil pressure in the reaction force adjusting device provided in each pile can be individually controlled. Needless to say, the adjusting device may employ various configurations other than those shown in FIGS. 2 and 3, including the conventional one shown in FIG. Furthermore, it is preferable that the controller as the control means is provided with a fail-safe function so as not to output an erroneous signal in preparation for a power failure that may occur in the event of an earthquake.

It is a schematic block diagram of the foundation structure which is embodiment of this invention. It is a figure which shows the structural example of a reaction force adjustment apparatus same as the above. It is a figure which shows the other structural example of a reaction force adjustment apparatus same as the above. It is explanatory drawing of a basic structure. It is a schematic block diagram of the conventional foundation structure. It is a figure which shows the structural example of a reaction force adjustment apparatus same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Structure 2 Pile 3 Foundation version 4 Reaction force adjustment apparatus 21 Extrapolated steel pipe (1st insertion body)
22 Internal steel pipe (second insert)
DESCRIPTION OF SYMBOLS 23 Friction generating means 24 Film | membrane 25 Oil accommodating part 26 Slit 27 Slit steel pipe 28 Oil supply pipe 40 Hydraulic source 41 Hydraulic supply apparatus 42 Pressure adjustment pump (hydraulic adjustment means)
43 Pressure distributor (hydraulic pressure adjusting means)
45 Displacement meter 47 Controller (control means)
48 Hydraulic adjustment valve

Claims (5)

A pile foundation that is driven or embedded in the ground or foundation slab, and the pile head is connected to the structure so as to be relatively displaceable to support the structure,
Of the first insertion body fixed to the structure, the second insertion body inserted or extrapolated in the first insertion body, and the first insertion body and the second insertion body The oil container is provided on one side, and the wall of the oil container presses the other wall surface of the first and second inserts by the oil pressure of the oil container, There is provided a reaction force adjusting device including a friction generating means for increasing the frictional force during insertion between the first insertion body and the second insertion body,
The reaction force adjusting device includes a displacement meter that detects a relative displacement between the foundation plate and the pile head, a hydraulic pressure adjusting unit that adjusts an oil pressure in the oil storage unit, and the hydraulic pressure based on a detection result of the displacement meter. A pile foundation comprising control means for adjusting the oil pressure by controlling the adjusting means.   The pile foundation according to claim 1, wherein a lubricant is applied to a sliding surface between the first insertion body or the second insertion body and a wall surface of the oil storage portion of the friction generating means.   The friction generating means includes an oil storage portion, oil filled in the oil storage portion, and a hydraulic pressure adjustment valve that adjusts the oil pressure in the oil storage portion, and is in contact with the wall surface of the first insertion body or the second insertion body. The pile foundation according to claim 1 or 2, wherein the wall of the oil storage portion is formed so as to be swellable by oil pressure.   A slit is formed in the wall of the oil container so that the wall can be easily deformed, and a stretchable film for maintaining liquid tightness in the oil container is formed inside the wall. The pile foundation according to claim 3, wherein the pile foundation is provided. The foundation structure is a combination of a direct foundation that uses ground reaction force and a pile foundation that uses the support force of the pile,
A foundation structure comprising the pile foundation according to claim 1, 2, 3, or 4 as the pile foundation.

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