JP6588585B2 - Pile construction management method - Google Patents

Description

  The present invention relates to a pile construction management method for building a ready-made pile in a pile hole drilled in the ground by a pre-boring method, an earth drill method, an all casing method, or the like.

  Conventionally, in the construction of ready-made piles by the pre-boring method, it is assumed that the ground is excavated by lowering while rotating the screw rod attached to the auger machine that moves up and down along the leader such as a three-point pile driver After forming a pile hole with a depth that reaches the support layer in the deep underground, injecting a root-setting liquid such as soil cement while pulling up the screw rod, and then injecting a perimeter fixing liquid up to the top of the pile hole, After extracting a screw rod, it is common to connect a ready-made pile such as a PHC pile or a PRC pile to the auger machine A via a connecting rod, and insert the ready-made pile into a pile hole and embed it.

  In general, it is possible to determine whether or not the support strength of piles after the completion of construction by these methods is sufficient by a loading test, but if it is found that the support strength is insufficient, it takes a lot of labor and time to redo the pile construction. It would be ideal if it was possible to determine whether or not the pile bearing hole had sufficient bearing capacity at the tip of the pile before the pile was built. Conventionally, from this point of view, there has been a method of capturing changes in excavation load from the current value of the rotation drive motor of the excavation member and confirming that the pile hole has reached a hard support layer deep in the ground due to this increase in excavation load. It has been proposed (Patent Documents 1 to 3).

  However, in the method of detecting the change in the excavation load from the current value of the rotation drive motor, the frictional resistance between the excavation member and the hole wall increases as the digging hole becomes deeper, so that the excavation can be performed even if it does not reach the support layer. Excessive increase in load, slippage at the excavation site, conversely, even if the support layer is reached, the excavation load decreases, and the excavation load varies greatly depending on the skill of the operator's excavation work. Therefore, it is poor in reliability as an index for confirming the arrival at the support layer. Therefore, in general, based on the data of the geological sample obtained exclusively by the test boring at the planned construction site, it is usually considered that the material reached the support layer by drilling to a predetermined depth. The underground depth of the entire construction site is not always uniform with a uniform stratigraphy. Depending on the geological history, the depth of the support layer may vary locally, or the difference in hardness of the support layer itself may be large. Since there are many cases, it cannot be said that the bottom of each pile hole actually has a sufficient support force of the pile tip.

  Therefore, the inventor previously arranged a penetration tester in the pile hole as a pile construction management method after forming a pile hole of a set depth in the ground and before laying the pile in the pile hole. It is proposed that a penetration test is performed, the support strength of the hole bottom is determined from the result, and the pile is built in the pile hole when the support strength is a predetermined value or more (Patent Document 4). . The penetration tester includes a knocking block in which a penetration shaft that protrudes downward from the lower end of the casing is integrated in a vertical cylindrical casing, a drive hammer that strikes the knocking block by free fall, and a drive hammer after the fall And a lifting mechanism that lifts and lowers at a predetermined height, and determines the support strength of the hole bottom from the number of impacts (N value) required for the bottomed penetration shaft to penetrate from the hole bottom to a predetermined depth. Therefore, it is possible to manage with the international standard N value, and a high reliability evaluation of the measured value can be obtained. In addition, the present inventor, as such a penetration tester, is a suspended type (Patent Document 5) that is hung with a crane wire to enter and exit a pile hole, a screw rod of an earth auger, a kelly bar of an earth drill, and the like. An excavating rod connection type in which the pile hole is connected to the excavation rod in place of the excavation target member after excavation (Patent Document 6), the inside of the hollow rod on the tip side of the screw rod in the earth auger, or the shaft excavation bucket in the earth drill Alternatively, a hollow rod built-in type drilling member incorporated in a hollow rod of a bottomed bucket (Patent Document 7) has been proposed.

JP-A-5-280031 JP 2000-245058 A JP 2003-74045 A Japanese Patent No. 5948435 Japanese Patent Application No. 2006-071845 Japanese Patent Application No. 2006-07832 Japanese Patent No. 5932178

  In the above-mentioned pile construction management method, if the support strength of the hole bottom does not satisfy the predetermined value as judged by the penetration tester before the pile is built, a new pile hole is formed at a different location, or the pile hole The drilling is further deepened and the re-penetration test is repeated until the support strength becomes a predetermined value or more. However, it is extremely difficult to form a new pile hole at a different location because it requires a change in the design of the building and causes a significant increase in construction cost and construction period. Therefore, it is realistic to excavate the pile hole deeper until the support strength becomes a predetermined value or more, but the ready-made pile carried into the construction site has a length corresponding to the initially set pile hole depth. Therefore, it cannot be applied to pile holes whose depth has been increased by re-digging. In addition, it is impossible to prepare various ready-made piles with different lengths in advance because the cost is too high and the work efficiency is high.

  In view of the above circumstances, the present invention performs re-excavation and re-determination of the pile hole when the support strength of the hole bottom is less than a predetermined value as determined by the penetration tester before the pile is built, Pile is built when the support strength reaches the specified value or higher, but piles with increased depth should be efficiently built at low cost using ready-made piles corresponding to the depth before re-excavation. The purpose is to provide a pile construction management method that makes it possible.

If the means for achieving the above-mentioned object is shown with reference numerals in the drawings, the pile construction management method according to the invention of claim 1 will form the pile hole H1 in the ground G after forming the pile hole H1 of the set depth. A knocking block in which a penetrating shaft 4 that protrudes downward from the lower end of the casing 3 is integrated into a longitudinal cylindrical casing (outer casing) 3 before the pile having a pile length corresponding to the set depth is built. 51, a penetration hammer 52 comprising a drive hammer 52 that strikes the knocking block 51 by free fall, and a lifting mechanism 8 that lifts the dropped drive hammer 52 and releases it at a predetermined height. The penetration shaft 4 of the penetration testing machines M1 to M3 arranged in the pile hole H1 is settled on the hole bottom Hb1, and the hole bottom Hb1 is calculated from the number of hits required for the penetration shaft 4 to penetrate from the hole bottom Hb1 to a predetermined depth. Support When the support strength is less than the predetermined value, the pile hole H is re-excavated further deeply, and the support strength of the hole bottom Hb2 after the re-excavation is similarly set by the penetration test machines M1 to M3. In this case, the digging depth of the re-digging is made uniform, and a plurality of piles having the same length corresponding to the uniform digging depth are prepared in advance, and the uniform digging depth is restored. When the support strength reaches a predetermined value or more by excavation, a pile having a length prepared in advance corresponding to the depth increase of the uniform excavation depth by re-excavation with respect to the pile length corresponding to the original set depth is used. A pile construction management method for building a pile that has been added and adjusted in the pile hole H2 ,
The pile body P1 having a pile length corresponding to the original set depth is a concrete pile, and the short pile member P2 corresponding to the depth increase of the uniform excavation depth by the re-excavation is a steel pipe pile P2A, P2B or P2C,
The steel pipe piles P2A, P2B, or P2C are fixed to a plurality of steel pipes 20 having the same length corresponding to a uniform excavation depth by re-excavation and the upper end of the steel pipe 20, and the concrete piles P1 A connecting ring member 21 welded and / or bolted to the steel end plate 12 fixed to the lower end portion;
By welding or / and bolting the connection ring member 21 at the upper end of the steel pipe 20 to the steel end plate 12 at the lower end of the concrete pile P1, a uniform increase in the depth of excavation by re-excavation was prepared in advance. As a pile adjusted by adding a pile of length, the pile adjusted by adding the pile is built in a pile hole after re-excavation .

The invention according to claim 2 is the pile construction management method according to claim 1 , wherein the penetration testing machine M1 is a suspension type, and the penetration testing machine M1 is suspended by the wire W of the crane to enter and exit the pile holes H1, H2. The configuration is to let

The invention of claim 3 is the pile construction management method according to claim 1 or 2 , wherein the penetration testing machine M2 is a drilling rod connection type, and the drilling tip member (tip rod member Rh, Instead of the shaft-drilling bucket B1 and the widened bucket B2), the penetration testing machine M2 is connected to enter and exit the pile holes H1 and H2.

According to a fourth aspect of the present invention, in the pile construction management method according to any one of the first to third aspects, the penetration testing machine M3 is a hollow rod built-in type excavation member, and the excavation destination is placed in the pile holes H1 and H2 after excavation. The penetration tester M3 is operated in a state where the member (the tip rod member Rh) is inserted to perform a penetration test.

Next, effects of the present invention will be described with reference numerals in the drawings. First, in the pile construction management method according to the invention of claim 1, after the pile hole H1 having the set depth is formed in the ground G, before the pile having a pile length corresponding to the set depth in the pile hole H1 is built. In addition, the penetration shaft 4 of a specific penetration testing machine M1 to M3 arranged in the pile hole H1 is grounded to the hole bottom Hb1 to determine the support strength of the hole bottom Hb1, but the support strength satisfies a predetermined value. When the pile hole H1 is re-excavated further deeply, the support strength of the hole bottom Hb2 after the re-excavation is similarly determined by the penetration test machines M1 to M3, and the support strength reaches a predetermined value or more. In addition, a pile that is adjusted by adding the length of the depth increase by re-excavation to the pile length corresponding to the original set depth is built in the pile hole H2. Therefore, according to this pile construction management method, even if the supporting strength of the hole bottom Hb1 of the excavated set depth of the pile hole H1 is insufficient, it is not necessary to form a new pile hole by changing the place, and the same pile hole Since it can respond by performing re-excavation and re-determination of H1, it is possible to avoid design changes of buildings, significant construction cost increase, construction period extension, etc., and ready-made piles prepared in advance for pile holes H1 with a set depth Since P can be used as a pile body P1 by simply adding only the shortage of the length, the material cost is low and the pile can be built efficiently. The re-digging and re-determination can be repeated until a support strength of a predetermined value or more is obtained.
At this time, since the excavation depth of the re-excavation is uniform and a plurality of piles having the same length corresponding to the excavation depth are prepared in advance, it is possible to respond quickly when re-excavation becomes necessary. .

In addition, according to the present invention , the short pile member P2 is added to the pile body P1 having a length corresponding to the pile hole H1 having the original set depth with respect to the pile hole H2 deepened by re-excavation in the construction of the ready-made pile. Since the connected pile PA is built, by making the uniform excavation depth of re-excavation correspond to the length of the short pile member P2, uniform pile construction management can be performed using the short pile member P2 of the same size and shape. .

Furthermore, according to the present invention , since the steel pipe 20 as the short pile member P2 is added and connected to the lower end of the pile main body P1 made of concrete piles, the connecting and connecting work can be easily and quickly performed. Further, by preparing those long as steel raw material of the steel pipe 20, steel pipe piles P2A cut lengths fraction corresponding from the steel raw material in the depth increases by re-drilling Kuiana H1, P2B Or it can be used for P2C2 .

According to the invention of claim 2 , since the penetration testing machine M1 is a suspension type, it can be efficiently moved in and out of the pile holes H1, H2 by being suspended by the crane wire W, and the penetration testing machine M can be easily operated. There is an advantage that it can be manufactured.

According to the invention of claim 3 , since the penetration testing machine M2 is of the excavating rod connection type, the screw rod Rs of the earth auger AA used for excavation of the pile holes H1 and H2, the kelly bar K of the earth drilling machine AD, etc. are used. Then, by connecting the penetration testing machine M2 instead of the excavation tip member (the tip rod member Rh, the shaft excavation bucket B1, the bottom expansion bucket B2), the pile hole H1, H2 can be efficiently moved in and out, There is an advantage that the penetration tester M2 can be easily manufactured.

According to the configuration of the fourth aspect , the penetration testing machine M3 is a hollow rod built-in type of excavation member, and excavation members excavating the pile holes H1, H2, for example, the screw rod Rs of the earth auger AA, the kelly bar of the earth drill machine AD. Since the shaft excavation bucket B1 and the bottom expansion bucket B2 etc. connected to K can be continuously extracted from the pile holes H1 and H2, the support strength of the hole bottoms Hb1 and Hb2 can be determined by the penetration test. Despite having a penetration test process in the middle, work efficiency is very good.

It is the whole perspective view which shows an example of the suspension type penetration testing machine used for the pile construction management method of this invention. The inside of the penetration testing machine is shown, (a) is a longitudinal front view, (b) is a cross-sectional view taken along line XX of (a). The inside of the hammer casing in the penetration tester is shown, (a) is a state in which the drive hammer in the fall position is gripped by the clamp part of the lifting mechanism, (b) is a drive hammer lifted to the upper limit position by the lifting mechanism It is a vertical front view of each in the state which opened. The penetration test operation by the penetration test machine is shown, (a) a state where the penetration test machine is bottomed in the pile hole, (b) is a longitudinal front view of the state where the penetration shaft is penetrated into the hole bottom. . It is a schematic longitudinal cross-sectional view which shows the process when the support strength of the hole bottom by a penetration test is more than predetermined value in the pile construction by the pre-boring method using the penetration testing machine in order of (a)-(g). . In pile construction by the pre-boring method, it is a schematic longitudinal cross-sectional view which shows the process after a penetration test when the support strength of the hole bottom by a penetration test is less than predetermined value in order of (a)-(f). The PHC pile used by the pre-boring method is shown, (a) is a front view of the lower part, (b) is a longitudinal sectional view of the lower part, and (c) is a bottom view. The steel pipe pile addition connection of the 1st structural example with respect to the PHC pile is shown, (a) is an exploded perspective view before connection, (b) is a front view after connection, (c) is a longitudinal cross-sectional view of a connection part. . The lower end part structure of the steel pipe pile is shown, (a) is a longitudinal cross-sectional view in which the lower end plate is an external fitting type, and (b) is a longitudinal sectional view in which the lower end plate is an internal fitting type. The joint connection of the steel pipe pile of the 2nd structural example with respect to the PHC pile is shown, (a) is an exploded perspective view before connection, (b) is a front view after connection. The steel pipe pile addition connection of the 3rd structural example with respect to the PHC pile is shown, (a) is an exploded perspective view before connection, (b) is a front view after connection, (c) is a longitudinal cross-sectional view of a connection part. . The modification of the steel pipe pile for extension is shown, (a) is each a front view of the steel pipe which provided the screw blade | wing on the outer periphery, (b) is the steel pipe which provided the annular blade | wing on the outer periphery at regular intervals. The earth auger used for a pre-boring method is shown, (a) is a whole side view, (b) is a side view of the principal part of the state which connected the drill rod connection type penetration test machine to the screw rod. FIG. 2 shows a kelly bar type earth drill machine, in which (a) is a side view of the whole, and (b) is a side view of a main part in a state where a drill rod connecting type penetration tester is connected to the kelly bar. The end rod member of a screw rod for earth auger incorporating a hollow rod built-in penetration tester is shown, (a) at the time of excavation, (b) at the time of test preparation, and (c) at the start of the test. It is. In pile construction by pre-boring method using a hollow rod built-in type penetration tester, a schematic longitudinal section showing the steps in the order of (a) to (g) when the support strength of the hole bottom by the penetration test is greater than or equal to a predetermined value. FIG. In pile construction by the pre-boring method, it is a schematic longitudinal cross-sectional view which shows the process after a penetration test when the support strength of the hole bottom by a penetration test is less than predetermined value in order of (a)-(f).

  Below, the embodiment of the pile construction management method concerning the present invention is described concretely with reference to drawings. In addition, the same code | symbol is attached | subjected to the component which is common in each embodiment.

  1 to 4 show a penetrating penetration testing machine M1 which is an example of a penetration testing machine used in the pile construction management method of the present invention. As shown in FIGS. 1 and 2, the penetration testing machine M 1 has a cylindrical hammer casing 5 mounted in a vertically cylindrical outer casing 3 so as to be movable up and down, and is attached to an upper taper cap 31 of the outer casing 3. The rod-like suspension member 6 projects vertically from the provided upper end opening 31a, and the penetrating shaft 4 projects vertically from the lower end opening 32a provided in the lower taper cap 32, while the upper end opening 31a The upper end opening 31a and the lower end opening are provided between the surrounding tube opening 31b and the upper portion of the suspension member 6, and between the tube opening 32b around the lower end opening 32a and the intermediate portion of the penetrating shaft 4. Bellows cylinders 7A and 7B for sealing the portion 32a to the outside are mounted, respectively. Further, at the lower part of the outer casing 3, a support leg 33 in which upper and lower large-diameter pipe rings 33 a and 33 b are connected by a plurality of (four in the figure) pipe columns 33 c, and the lower pipe ring 33 b is connected to the outer casing 3. It is fixed via brackets 33d arranged radially on the upper side so as to be lower than the lower end.

  In this penetration test apparatus M1 for pile holes, the hook Ho suspended at the lower end of a wire (not shown) suspended from the boom or the like of a crawler crane is passed through a suspension fitting 61 connected to the upper end of the suspension support member 6. By hanging the hanging ring 62 made of the wire, the entire apparatus is suspended to enter and exit the pile hole H (see FIG. 4), while the entire apparatus maintains an upright posture by the support legs 33 when the pile hole H is settled. It is like that.

  As shown in FIG. 2A, the suspension support member 6 has a lower end pivotally connected to the upper end of the hammer casing 5 via a pivot pin 63, but is attached to an intermediate portion located inside the outer casing 3. A circular flange-like stopper 60 is provided, and the outer casing 3 when the apparatus is suspended is supported on the inner side of the upper taper cap 31 via the stopper 60. And in this apparatus suspended state, the front-end | tip of the penetration shaft 4 is set so that it may become the same level or a slightly high position with respect to the lower end of the support leg 33, ie, the lower side pipe ring 33b. As shown in FIGS. 2 (a) and 2 (b), guide rails 33 constituted by two parallel strips along the vertical direction are provided on the inner periphery of the outer casing 3 at a plurality of locations in the circumferential direction (4 in the figure). The fitting keys 53 are formed at equal positions at the upper and lower portions of the outer periphery of the hammer casing 5 and are slidably fitted to the guide rails 33. The penetrating shaft 4 is made of steel and has a cylindrical shaft shape with an open front end. However, a sampler 41 composed of a split barrel (not shown) whose front end side can be divided into two so that a geological sample can be collected. It has become.

  Further, a mounting plate 34 is fixed on the inner upper portion of the outer casing 3, and a hydraulic cylinder 80 (described later) in the hammer casing 5 is provided between the lower surface side of the mounting plate 34 and the upper end of the hammer casing 5. 2), two double-pipe expansion and contraction pipes 81 and 81 constituting the hydraulic oil supply / discharge path are interposed. An encoder 9 for measuring the descending amount of the hammer casing 5 with respect to the outer casing 3 is attached to the lower surface side of the mounting plate 34, and a measurement cord 9 a extending from the encoder 9 is fixed to the upper end of the hammer casing 5. Has been. Between the attachment plate 34 of the outer casing 3 and the upper taper cap 31, a hydraulic hose h connected to the upper end side of each telescopic pipe 81 and an electrical wiring e for the encoder 8 are disposed. The upper taper cap 31 is provided with hose connecting cylindrical shaft portions 31c projecting upward on both sides of the upper end opening portion 31a, and external hydraulic pressure supply sources (not shown) are provided on both cylindrical shaft portions 31c and 31c. Are connected via an adapter a, and one hydraulic hose h2 has an electrical wiring e for the encoder 9 inserted between the double structures. Further, a through hole 34a is formed in the center of the mounting plate 34, and the suspension support member 6 passes through the through hole 34a.

  The upper and lower bellows cylinders 7A and 7B are formed in a bellows shape having the same diameter as a whole by a flexible material such as rubber or semi-rigid synthetic resin, and the hammer casing 5 moves up and down in the outer casing 3. The other contracts in response to one stretching. Thus, both the bellows cylinders 7A and 7B are formed into an elongated cylindrical shape when extended, but in order to prevent being crushed by water pressure, a metal ring 71 for shape retention is provided on the inner side for each ridge (valley). Is fitted. Further, both end portions of the bellows cylinders 7A and 7B are liquid-tight with respect to the cylinder opening portions 31b and 32b of the upper and lower taper caps 31 and 32, the suspension member 6 and the penetrating shaft 4 by a fastener 72 such as a fastening band. It is fastened.

  As shown in FIG. 3, the hammer casing 5 has a knocking block 51 fixed to the lower end, a drive hammer 52 that strikes the knocking block 51 by free fall inside, and a drive hammer 52 that has been dropped is lifted to a predetermined height. And a lifting mechanism 8 that is released at the bottom, and the penetrating shaft 4 is fixed to the lower surface of the knocking block 51 by a disc portion 4a at the upper end. The lifting mechanism 8 includes a pair of clamp arms 83, 83 pivotally mounted on a vertically bifurcated pivot support frame 82 fixed to the distal end of the telescopic rod 80 a of the hydraulic cylinder 80. A short cylindrical gripping release tube 84 is fixed to the outer peripheral portion of the lower end of the hydraulic cylinder 80 as an annular tapered surface 84a that opens downward and expands the lower portion of the inner periphery downward. Each clamp arm 83 is provided with an inwardly engaging claw 83a at each lower end, and an outer surface side of the upper end portion is an upward inclined surface 83b. The clamp arms 83 and 83 are urged in the closing direction in which the locking claws 83a and 83a approach each other by a coil spring 85 interposed between upper ends facing each other. Note that the two hydraulic hoses h and h led out from the hydraulic cylinder 80 of the lifting mechanism 8 are connected to the upper expansion pipe 81, respectively. On the other hand, in the center of the upper surface of the drive hammer 52, a locking shaft 52a having a top portion having a large truncated cone portion 52b is implanted.

  In the lifting mechanism 8, when the drive hammer 52 is in the dropping position in the hammer casing 5, the piston rod 80 a of the hydraulic cylinder 80 is extended to extend both clamp arms 83, 83 as shown in FIG. The taper surfaces of the locking claws 83a and 83a come into contact with the truncated cone portion 52b of the locking shaft 52a of the drive hammer 52, and both the clamp arms 83 and 83 resist the biasing force of the coil spring 85 by the tilt induction action. By opening, both locking claws 83a, 83a engage with the lower side of the truncated cone portion 52b. In this engaged state, the piston rod 80a is contracted to hold and lift the drive hammer 5. When the piston rod 80a reaches the upper limit position, as shown in FIG. The inclined surfaces 83b and 83b at the upper ends of the clamp arms 83 and 83 come into contact with the tapered surface 84a of the grip release cylinder 84, and both the clamp arms 83 and 83 are forcibly resisted against the bias of the coil spring 85 by the inclination inducing action. Therefore, the released drive hammer 52 falls freely and strikes the knocking block 51 at the bottom end of the hammer casing 5, and the hammer casing 5 is moved downward by the impact force, and the penetrating shaft 4 is lowered accordingly. Become.

  Therefore, this penetration testing machine M1 is hung with a wire via a boom of a crawler crane, inserted into a pile hole H drilled in the ground G as shown in FIG. By loosening and lowering the wire that has been lowered, the hammer casing 2 in the outer casing is lowered by its own weight, and the tip of the penetrating shaft 4 comes into contact with the hole bottom Hb. In this state, the penetration testing machine M1 is driven, and the impact by the drive hammer 52 is repeated, so that the penetration shaft 4 penetrates into the ground of the hole bottom Hb as shown in FIG. 4 (b). The number of impacts required for the penetration shaft 4 to penetrate from the hole bottom Hb to a predetermined depth is measured, and it can be determined whether or not the support strength of the ground of the pile bottom Hb is greater than or equal to a predetermined value based on the number of impacts. .

  The number of hits (N value) of the drive hammer 52 is counted by a hydraulic drive control device (not shown) on the ground side that controls the operation of the hydraulic cylinder 80, and the penetration amount of the penetration shaft 4 into the hole bottom ground is the descent of the hammer casing 5. The quantity is measured by the encoder 9. Then, the measurement signal from the encoder 9 is sent to an automatic measuring device (not shown) on the ground through the electric wiring e, and the amount of subsidence per hit, that is, the penetration amount and the total penetration amount of the penetration shaft 4 with respect to the ground G are the number of hits ( N value) is recorded and displayed. In the standard penetration test stipulated in JIS A 1219, a drive hammer having a mass of 63.5 ± 0.5 kg is freely dropped by 76 ± 1 cm, and the knocking block is hit, and the outer diameter is 51 ± 1 mm and the inner diameter is 35 ± 1 mm. Since the number of impacts required for the penetration shaft to penetrate 30 cm into the ground is expressed as an N value, the penetration strength tester M1 may hold the support strength as the N value in accordance with the standard penetration test.

  As a pile construction management method using the penetrating penetration tester M1, the pile construction according to the first embodiment by the pre-boring method will be described in the order shown in FIGS. In this pile construction, a screw rod Rs is attached to an auger machine A that moves up and down along a leader (not shown) such as a three-point pile driver, and the screw rod Rs is lowered while being driven to rotate. After excavating the ground G, (b): after forming a pile hole H1 with a depth reaching the support layer Gh in the deep underground, the same (c): Roots of soil cement etc. while lifting the screw rod Rs (D): Subsequently, the hole periphery fixing liquid Lf is injected up to the top of the pile hole H, the screw rod Rs is extracted, and then (e): the three-point pile driver or the like The penetration test machine M1 suspended by a wire W such as a crane is inserted into the pile hole H1 and settled on the hole bottom Hb1, and the support strength of the above-mentioned pile bottom ground is measured in the relaxed state of the wire W. If the supporting strength is equal to or greater than a predetermined value, the same (f): a ready-made pile P such as a PHC pile or a PRC pile is attached to the auger machine A via a connecting rod Rj, and the ready-made pile P is attached to the pile hole H1. (G): The bottom of the pile hole H1 is buried to complete the construction of the ready-made pile P.

  However, for example, as shown in FIG. 6 (a), the penetration tester has a structure in which the support layer Gh in the deep underground is deeper than originally assumed and the pile hole H1 does not reach the support layer Gh. When the support strength of the pile bottom ground measured at M1 is less than a predetermined value, the pile construction management method of the present invention is applied. That is, for the pile hole H1 extracted from the penetration testing machine M1, FIG. 6 (b): a deeper pile hole H2 is formed by inserting the screw rod Rs again and excavating, The re-drilling depth of this deep excavation pile hole H2 is uniform, and after forming the excavation hole H2 of this uniform excavation depth, the root-setting liquid Ls is additionally injected while pulling up the screw rod Rs. (C): The penetration test machine M1 suspended by the wire W is inserted again into the pile hole H2 after re-excavation and settled, and the support strength of the pile bottom ground is measured in the same manner as described above. And if this support strength is more than predetermined value by the pile hole H2 of this uniform cutting depth having reached the support layer Gh which was in a deeper position than originally assumed, etc., (d): A ready-made pile PA in which a ready-made pile P for an assumed pile hole H1 is used as a pile body P1, and a short pile member P2 having a uniform length corresponding to the pile hole H2 having a uniform depth is added to the pile body P1. (E): Insert the ready-made pile PA into the pile hole H2 after re-excavation in the same manner as described above. (F): Complete the construction of the ready-made pile PA by embedding it to the bottom of the pile hole H2. To do.

  In addition, when the support strength of the pile bottom ground measured also in this pile hole H2 after re-excavation does not satisfy a predetermined value, the same re-excavation and re-measurement may be repeated until the support strength becomes a predetermined value or more. . However, the repetition of this is naturally limited in terms of both cost and time. Therefore, if the support strength is usually insufficient after several re-excavations and re-measurements, the site is considered unsuitable for pile construction. The position will be changed.

  For the ready-made pile PA to be inserted into the pile hole H2 after re-excavation, the ready-made pile P corresponding to the initially assumed pile hole H1 is used as the pile body P1, and the short pile member P2 is added to the pile body P1 and re- Although the length corresponds to the pile hole H2 after excavation, when the pile body P1 is a concrete pile such as a PHC pile or a PRC pile, a steel pipe pile is added and connected as the short pile member P2. It is simple.

  That is, in concrete piles such as PHC piles and PRC piles, as shown in FIGS. 7 (a) to (c), an annular steel end plate 12 contacting the end surface of the concrete cylinder 11, and The steel reinforcing band 13 that goes around the outer peripheral surface is fixed. The steel end plate 12 is provided with screw holes 12a and steel wire holes 12b arranged on both sides thereof at a plurality of locations (9 locations in the figure) equally distributed in the circumferential direction. On the other hand, the steel pipe pile used for the short pile member P2 is not particularly limited in structure, but is suitable for addition connection by welding or / and bolting, such as a steel pipe pile P2A shown in FIG. 8 and a steel pipe pile P2B shown in FIG. A steel pipe pile P2C shown in FIG.

  As shown in FIG. 8A, the steel pipe pile P2A is composed of a steel pipe 20 having a retaining ring 20a fixed to the outer periphery of the upper end, a connecting ring member 21 fitted to the upper end, and a bottom plate 22 fitted to the lower end. It is configured. The connecting ring member 21 is formed by integrally fixing a horizontal annular flange portion 21b to an upper end of a vertical annular ring portion 21a to be fitted into an upper end opening of the steel pipe 20, and the pile body is attached to the flange portion 21b. A bolt insertion hole 21c corresponding to each screw hole 12a of the steel end plate 12 at P1 is formed. Further, the bottom plate 22 is formed by integrally fixing a horizontal annular flange portion 22b to a lower end of a vertical annular ring portion 22a. And in order to add and connect the steel pipe pile P2A to the pile main body P1, the flange portion 21b of the connection ring member 21 is joined to the steel end plate 12 of the pile main body P1 and fixed via the bolt 23, and this connection ring member After the upper end side of the steel pipe 20 is externally fitted to the ring portion 21a of 21, the outer peripheral side of the joint portion between the steel end plate 12 and the flange portion 21b of the connecting ring member 21 is welded, and then the outer peripheral edge of the flange portion 21b The bottom ring 22 may be welded to the bottom end opening of the steel pipe 20, and the bottom ring 22 may be finally welded.

  Thus, in FIG. 8B, the bottom plate 22 has the ring portion 22a externally fitted to the steel pipe 20, but the ring portion 22a may be internally fitted to the steel pipe 20. In the outer fitting type bottom plate 22, as shown in FIG. 9A, the outer peripheral surface of the steel pipe 20 and the upper peripheral edge of the ring portion 22a are welded b. Moreover, in the internal fitting type bottom plate 22, as shown in FIG.9 (b), the outer peripheral lower end part of the steel pipe 20 and the upper surface side of the flange part 22b are welded b. The same applies to the bottom plate 22 in the steel pipe pile P2B and the steel pipe pile P2C described below.

  As shown in FIG. 10A, the steel pipe pile P2B includes a steel pipe 20, a connecting tenon member 24 fixed to the upper end thereof, and a bottom plate 22 similar to the above. The connecting tenon member 24 is formed by integrally projecting a vertical cylindrical tenon portion 24b at the center of a horizontal annular base portion 24a. Then, the steel pipe pile P2B is connected to the pile body P1 with the base portion 24a of the connecting tenon member 24 welded and fixed to the upper end of the steel pipe 20, as shown in FIG. What is necessary is just to insert inside the pile main body P1, and to weld-fix the outer peripheral side of the junction part of the steel end plates 12 and the base part 24a.

  As shown in FIG. 11 (a), the steel pipe pile P2C is composed of a steel pipe 20, a horizontal annular end plate 25 fixed to the upper end thereof, and a bottom plate 22 similar to the end plate. An annular groove 25 a is provided on the outer peripheral side of the upper surface of 25. Then, the steel pipe pile P2C is connected to the pile body P1 by joining the end plate 25 to the steel end plate 12 of the pile body P1 in a state where the end plate 25 is welded and fixed to the upper end of the steel pipe 20 on the outer peripheral lower edge side. The outer peripheral portion of the steel end plate 12 may be welded and fixed at the annular groove 25a portion of the end plate 25.

  The steel pipes 20 used for these steel pipe piles P2A to P2C are previously loaded with a long steel pipe raw material at the construction site, and the length corresponding to the depth increase of the pile hole H2 by the re-excavation from the steel pipe raw material. If the steel pipe piles P2A to P2C are formed in combination with the connecting ring member 21, the bottom plate 22, the connecting tenon member 24, the end plate 25, etc., it is possible to cope with the difference in depth due to re-excavation. On the other hand, if the excavation depth of re-excavation is made uniform and a plurality of steel pipes 20 having the same length corresponding to the excavation depth are prepared in advance, it is possible to respond quickly when re-excavation becomes necessary.

  Moreover, although the steel pipe main body 20 is shown as a simple cylindrical shape in the steel pipe piles P2A to P2C, in order to increase the pull-out resistance as a pile, a spiral blade 20b as shown in FIG. Various attachment forms, such as providing the annular flange 20c at predetermined intervals as shown in FIG. In addition to the above welding and / or bolting as means for connecting and connecting the short pile member P2 to the pile main body P1, for example, the outer peripheral taper is divided into the outer periphery of the joint between the pile main body P1 and the short pile member P2. A variety of mechanical methods, such as a method in which a ring-shaped locking ring is fitted between both P1 and P2, and an inner taper-shaped fastening ring is forcibly slide-fitted to the outside to fix the connecting portion. A connection method can also be adopted.

  Even in a drilling rod connection type or hollow rod built-in type penetration tester, a knocking block in which a vertically protruding penetration shaft is integrated in a vertical cylindrical casing, and a drive hammer that hits the knocking block by free fall And a lifting mechanism that lifts the drive hammer after dropping and releases it at a predetermined height, and determines the support strength of the hole bottom from the number of impacts required for the bottomed penetration shaft to penetrate the hole bottom to a predetermined depth. The basic configuration is the same as the illustrated suspension type. 13 and 14 illustrate a drill rod connecting type penetration tester M2, and FIG. 15 illustrates a hollow rod built-in type penetration tester M3. 6 (Japanese Patent Application No. 2006-07832) and the hollow rod built-in type penetration tester are described in detail in Patent Document 7 (Patent No. 5932178) described above. Omitted.

  FIG. 13A shows an earth auger AA used for the pre-boring method. In this earth auger AA, an auger machine AM is mounted on a leader Le held vertically of a three-point support pile driver, and a screw rod Rs is held at the upper end of the auger machine AM. This screw rod Rs is formed with a spiral blade Sc formed over the entire length of a straight hollow rod R, and is composed of an independent short tip rod member Rh having a digging blade E at its lower end. Thus, as shown in FIG. 13 (b), after forming the pile hole H in the ground G, the tip rod member Rh connected to the lower end of the screw rod Rs is used to determine the support strength of the hole bottom. Instead, a drill rod connecting type penetration tester M2 is connected to the lower end of the screw rod Rs for use.

  FIG. 14A shows an earth drill machine AD used in the Keriba type earth drill method. This earth drill machine AD is composed of a traveling crane equipped with a boom Bo and a front frame F. A kelly drive device KD is held at the tip of the front frame F projecting obliquely forward, and the boom Bo passes a hoisting rope W. A suspended kerry bar K is inserted through the kelly drive device KD so as to be movable up and down. A rotary table RT having a pair of hose reels Hr is attached to the lower part of the kelly drive device KD. The RT is provided with a rotary coupling (not shown) for hydraulic and electric wiring. Then, a shaft digging bucket B1 indicated by a solid line and a bottom expansion bucket B2 indicated by a phantom line are connected to the lower end of the kelly bar K so as to perform excavation of the ground G or bottom expansion after digging. Then, as shown in FIG. 19 (b), after forming the pile hole H in the ground G, in order to determine the support strength of the hole bottom, the shaft-drilling bucket B1 connected to the lower end of the kelly bar K Instead of the expanded bucket B2, an excavation rod connection type penetration tester M2 is connected to the lower end of the kelly bar K for use. Ps is a stunt pipe.

  A hollow rod built-in type penetration tester for a drilling member is incorporated in a tip rod member Rh having a hollow shape of a screw rod Rs shown in FIG. 13 (a), or a shaft digging bucket B1 shown in FIG. 14 (a). And is incorporated into the hollow shaft portion of the bottomed bucket B2. As a specific example, FIGS. 15A to 15C show an example in which the penetration tester is incorporated in the tip rod member Rh of the screw rod Rs.

  As shown in the figure, the tip rod member Rh has a penetration tester M3 built in a cylindrical hollow rod 100, and a connecting convex block 110 projects from an upper end plate 101 of the hollow rod 100, A round hole-shaped opening 103 is formed at the center of the lower end plate 102, and a movable sealing plate 104 that normally closes the opening 103 from below is attached by a biased spring (not shown). In addition, a spiral blade Sc is fixed over the entire length of the outer periphery of the hollow rod 100, and a plurality of excavation blades E project from the lower edge of the spiral blade Sc. The hollow rod 100 is provided with a grout discharge port 105 opening laterally at the lower end side, and a grout pipe 120 extending from the central hole 110a of the connecting convex block 110 to the grout discharge port 105 is provided in the hollow rod 100. It is.

  In the penetration tester M3, a cylindrical hammer casing 5 is loaded in a cylindrical outer casing 3 concentrically disposed and fixed in the hollow rod 100 so as to be movable up and down, and from the lower end of the hammer casing 5. A protruding penetrating shaft 4 hangs down. Between the lower end of the hammer casing 5 and the opening 103 at the lower end of the hollow rod 100, an expandable bellows made of a flexible material such as rubber or semi-rigid synthetic resin so as to surround the penetration shaft 4. A cylindrical body 7C is attached. In addition, although illustration is abbreviate | omitted, in the hammer casing 5, the knocking block 51, the drive hammer 52, and the lifting mechanism 8 (refer FIG. 3) are provided similarly to the suspension type penetration testing machine M1 already described.

  On the upper side in the outer casing 3, a hydraulic cylinder 201 having a downwardly extending telescopic rod 201a as a casing displacing means 200 is suspended, and a locking head whose lower end is pointed in an inverted conical shape at the tip of the telescopic rod 201a. While the locking shaft 203 as 203a is fixed, four clamp arms 205 equally arranged in the circumferential direction are pivotally attached to the upper end of the hammer casing 5 so as to be tiltable inward and outward. A sensor ring 204 for confirming the position with respect to the clamp arm 205 is fitted on the upper side of the locking head 203 above the locking head 203a so as to be movable up and down. Further, inwardly engaging claws 205a are formed at the upper ends of the clamp arms 205, and the clamp arms 205 are urged together in a standing direction by a spring (not shown). Although not shown, an encoder for measuring the amount of descent of the hammer casing 5 is provided on the upper side of the outer casing 3 in the same manner as the above-described penetrating penetration testing machine M1 [see FIG. 2 (a). ] Is attached.

  Thus, in the screw rod RS in which the penetration test machine M3 is built in the tip rod member Rh, when the penetration test machine M3 is not used, the expansion rod 203 of the hydraulic cylinder 201 is engaged as shown in FIG. By contracting with the clamp arm 205 engaged with the stop head 203 a, the hammer casing 5 is held at the upper standby position in the outer casing 3, and the penetrating shaft 4 is accommodated in the hollow rod 100. The opening 103 at the lower end of the hollow rod 100 is closed by a movable sealing plate 104. Therefore, there is no concern that the penetrating shaft 4 touches the ground or crushed material during the excavation process by the screw rod RS, and mud sand, sand gravel, mud water, etc. generated by excavation does not enter the outer casing 3.

  On the other hand, when measurement is performed by the penetration testing machine M3 after the formation of the pile hole, as shown in FIG. 15 (b), first, the piston rod 201a of the hydraulic cylinder 201 is extended to thereby lock the locking head of the locking shaft 203. At 203a, the clamp arms 205 are pushed outward against the bias of the spring force, and the hammer casing 5 held at the upper standby position is pressed and moved downward. As the hammer casing 5 moves downward, the penetrating shaft 4 pushes open the movable sealing plate 104 and protrudes downward from the opening 103. Next, as shown in FIG. 15C, the piston rod 201a of the hydraulic cylinder 201 By rapidly shortening, the locking head 203a is disengaged upward from the clamp arm 25, and the unlocked hammer casing 5 is lowered by its own weight until the tip of the penetrating shaft 4 reaches the bottom of the hole. . Therefore, by driving the penetration testing machine M3 in this bottomed state, it is determined whether or not the support strength of the ground at the bottom of the pile is equal to or higher than a predetermined value in the same manner as the suspension type penetration testing machine M1 described above. it can.

  When the penetration test is finished, the piston rod 201a of the hydraulic cylinder 201 is extended to interrupt the locking head 203a of the locking shaft 203 between the clamp arms 205, and the locking head 203a. By engaging the locking claws 205a of each clamp arm 205 and shortening the hydraulic cylinder 201 in this locked state, the hammer casing 5 can be lifted to the upper standby position and held.

  The pile construction management method in the pre-boring method using this hollow rod built-in penetration test machine M3 will be described in the order of steps shown in FIGS. In this pile construction, a screw rod Rs is attached to an auger machine A that moves up and down along a leader (not shown) such as a three-point pile driver, and the screw rod Rs is lowered while being driven to rotate. After excavating the ground G, (b): after forming a pile hole H1 having a depth reaching the support layer Gh in the deep underground, the same (c): slightly lifting the screw rod Rs to In this state, the penetration shaft 4 of the penetration tester M3 built in the tip rod member Rh protrudes downward to land on the hole bottom Hb1, and the support strength of the pile bottom ground is measured as described above. If the supporting strength is equal to or greater than a predetermined value, the same (d): the root-setting liquid Ls such as soil cement is injected while pulling up the screw rod Rs, and the same (e): the hole periphery fixing liquid Lf is subsequently piled. After injecting up to the upper part of the hole H and extracting the screw rod Rs, the same (f): A ready-made pile P such as a PHC pile or a PRC pile is attached to the auger machine A via the connecting rod Rj. Is inserted into the pile hole H1, and (g): the bottom of the pile hole H1 is embedded to complete the construction of the ready-made pile P.

  However, for example, as shown in FIG. 17 (a), the penetration testing machine is configured such that the support layer Gh in the deep underground is deeper than originally assumed and the pile hole H1 does not reach the support layer Gh. When the support strength of the pile bottom ground measured in M3 is less than a predetermined value, the pile construction management method of the present invention is applied. That is, the screw rod Rs after the penetration test inserted into the pile hole H1 is used as it is, and the penetration shaft 4 of the penetration test machine M3 is retracted, and then FIG. 17B: the pile hole H1 is re-excavated. After forming the deeper pile hole H2, the same (c): With the screw rod Rs slightly lifted and the excavating blade E detached from the bottom, the penetration shaft 4 of the penetration testing machine M3 is moved in the same manner as the previous time. The bottom is grounded to the hole bottom Hb2, and the support strength of the pile bottom ground is measured again. And if this support strength is more than predetermined value because this pile hole H2 has reached the support layer Gh which was deeper than originally assumed, etc., the root-solidifying liquid Ls and the hole are lifted while pulling up the screw rod Rs. After injecting the peripheral fixing liquid Lf, the same (d): using the ready-made pile PA in which the pre-made pile P for the initially assumed pile hole H1 is connected to the pile main body P1 by adding the short pile member P2 to the pile main body P1, (E): The ready-made pile PA is inserted into the pile hole H2 after the re-excavation, and (f): the built-in of the ready-made pile PA is completed by embedding to the bottom of the pile hole H2. In addition, the ready-made pile PA which added and connected the short pile member P2 to this pile main body P1 is the same as that of what was described in 1st embodiment as stated above.

  As described above, according to the pile construction management method of the present invention, even if the support strength of the hole bottom Hb1 of the excavated set depth pile hole H1 is insufficient, it is necessary to form a new pile hole at a different location. Since it can be handled by re-excavating and re-determining the same pile hole H1, it is possible to avoid changes in the design of the building, a significant increase in construction cost, extension of construction period, etc. Since the ready-made pile P can be used as a pile main body P1 by simply adding only the shortage of the length, the material cost is not increased and the pile can be built efficiently. In addition, by using the short pile member P2 corresponding to the depth increase due to re-excavation in the construction of ready-made piles, it is possible to easily cope with the depth increase due to re-excavation, and the short size of the same size and shape. Uniform pile construction management can be performed using the pile member P2.

B1 Shaft-drilling bucket (drilling destination member)
B2 Expanded bucket (Drilling destination member)
G Ground H1, H2 Pile hole Hb1, Hb2 Hole bottom M1-M3 Penetration test machine P Ready-made pile P1 Pile body P2 Short pile member P2A-P2C Steel pipe pile PA Ready-made pile Rh Tip rod member (drilling tip member)
W wire 3 outer casing (casing)
4 Penetration shaft 51 Knocking block 52 Drive hammer 8 Lifting mechanism

Claims (4)

After forming a pile hole with a set depth in the ground, before building a pile with a pile length equivalent to the set depth into the pile hole,
A knocking block in which a penetrating shaft that protrudes downward from the lower end of the casing is integrated in a vertical cylindrical casing, a drive hammer that strikes the knocking block by free fall, and a drive hammer that has been dropped is lifted to a predetermined height. Using a penetrating tester equipped with a lifting mechanism
The penetration shaft of the penetration tester placed in the pile hole is grounded to the bottom of the hole, and the support strength of the bottom of the hole is determined from the number of impacts required for the penetration shaft to penetrate from the bottom of the hole to a predetermined depth. When the support strength is less than a predetermined value, the pile hole is re-excavated further deeply, and the support strength of the hole bottom after the re-excavation is similarly determined by the penetration testing machine,
At this time, the digging depth of re-digging is made uniform,
And prepare a plurality of piles of the same length corresponding to the uniform re-digging depth in advance,
When the support strength reaches a predetermined value or more by re-excavation with a uniform excavation depth, the amount of increase in the uniform excavation depth by re-excavation in advance for the pile length corresponding to the original set depth A pile construction management method in which a pile having a prepared length is added and adjusted to be built in the hole ,
The pile body of the pile length corresponding to the original set depth is a concrete pile, and the short pile member corresponding to the depth increase of the uniform excavation depth by the re-excavation is a steel pipe pile,
The steel pipe pile is made of a plurality of steel pipes having the same length corresponding to a uniform excavation depth by re-excavation, and a steel pipe fixed to the upper end of the steel pipe and fixed to the lower end of the concrete pile. A connecting ring member welded and / or bolted to the end plate,
A pile with a pre-prepared length corresponding to the increased depth of uniform excavation depth by re-excavation by welding or / and bolting the connecting ring member at the upper end of the steel pipe to the steel end plate of the lower end of the concrete pile A pile construction management method characterized in that , as a pile that has been added and adjusted, the pile that has been added and adjusted is built in a pile hole after re-excavation .   The pile construction management method according to claim 1, wherein the penetration tester is a suspension type, and the penetration tester is suspended by a crane wire to enter and exit the pile hole.   The pile construction management method according to claim 1 or 2, wherein the penetration testing machine is a drilling rod connection type, and the pile hole is connected to the drilling destination member after excavation and the penetration testing machine is connected to enter and exit the pile hole.   The penetration test machine is a hollow rod built-in type of excavation member, and the penetration test machine is operated in a state in which the excavation member is inserted into the pile hole after excavation to perform a penetration test. The pile construction management method described in 1.

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