JP5994035B1 - Pile hole penetration test device and pile construction management method - Google Patents

Abstract

Provided is a pile hole penetration test apparatus which can be settled in a pile hole formed in the ground and immediately determine the supporting force of the pile bottom ground. A penetrating test apparatus M for a suspended pile hole, in which a hammer casing 2 is loaded in an outer casing 1 so as to be movable up and down, and a suspension support member 3 passes through an upper end side opening 11a of the outer casing 1 and a hammer. Bellows cylinders 5A and 5B are fixed to the upper end portion of the casing 2 and the penetration shaft 4 at the lower end of the hammer casing 2 protrudes from the lower end side opening portion 12a of the outer casing 1 to seal the both end opening portions 11a and 12a. Prepare. The hammer casing 2 includes a drive hammer 22 that strikes the knocking block 21 at the lower end by free fall and a lifting mechanism 6 that lifts the dropped drive hammer 22 and releases it at a predetermined height. A support leg 13 is provided at the lower part of the outer casing 1, the outer casing 1 is supported when suspended through a stopper 30 of the suspension member 3, and the penetrating shaft 4 contacting the hole bottom Hb at the bottom is a predetermined depth. It is comprised so that the support strength of a hole bottom ground may be measured from the frequency | count of impact required for penetrating. [Selection] Figure 2

Description

  The present invention relates to a pile hole penetration test device for examining the support strength of a pile bottom ground in a pile hole drilled in the ground by an earth drill method, an all-casing method, a pre-boring method, and the like. It relates to the pile construction management method used.

  Conventionally, the Keriba-type earth drill method and the all-casing method have been widely used for the construction of cast-in-place piles. In the former Keriba-type earth drill method, the ground is excavated and soiled by a shaft excavator bucket connected to the Keriba of the earth drill machine, a stunt pipe is press-fitted into the drill hole, and a stable liquid such as bentonite liquid is injected into the hole However, excavation and earth excavation with a small-diameter shaft exchanging bucket was performed, and a pile hole with a depth reaching the support layer in the deep underground was formed, and a reinforcing rod and treme tube were inserted into this pile hole. After the slime is discharged by introducing air, the cast-in-place piles are built in such a way that raw concrete is placed and the tremy pipe and stunt pipe are pulled out. In addition, as a bottom-pile construction, a cast-in-place pile is often built after the bottom of the pile hole is enlarged with a bottom-up bucket.

  In the all-casing method, a steel casing tube is rocked or / and rotated all around and pressed into the ground by a tubing device placed on the ground at the drilling position, and the inside is excavated and discharged with a hammer grab. Then, after forming a pile hole with a depth that reaches the support layer in the deep underground assumed by the addition of the casing tube, and processing the bottom of the hole with a hammer grab or sedimentation bucket, The cast-in-place pile is built by inserting the treme tube and pulling out the casing tube and the treme tube while placing the raw concrete.

  On the other hand, in the construction of ready-made piles by the pre-boring method, the ground is excavated by excavating the ground by lowering 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 deep support layer, pull up the screw rod and inject a root-setting liquid such as soil cement, and then inject a hole-periphery fixing liquid to the top of the pile hole. After extracting the rod, it is common to connect a pre-made pile such as a PHC pile or RC pile to the auger machine A via a connecting rod, and insert the pre-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.

JP-A-5-280031 JP 2000-245058 A JP 2003-74045 A

  In view of the above-mentioned circumstances, the present invention can reliably and easily determine whether or not the supporting force of the pile bottom ground is sufficient immediately after forming the pile hole in the ground by various methods, and thus due to insufficient support strength. An object of the present invention is to provide a pile hole penetration test device that makes it possible to save the trouble of re-working pile erection work, and a pile construction management method that uses this pile hole penetration test device.

  If means for achieving the above object is shown with reference numerals in the drawings, the invention of claim 1 suspends the entire apparatus with a cable body (wire) W, and inserts it into a pile hole to make it settle. A penetrating test apparatus M for a suspended pile hole, in which a cylindrical hammer casing 2 is loaded in a vertically cylindrical outer casing 1 so as to be movable up and down, and a suspension support member 3 to be engaged with a rope W is an outer side. A penetrating shaft 4 which is fixed to the upper end portion of the hammer casing 2 through the upper end side opening portion 11a of the casing 1 and protrudes concentrically downward at the lower end of the hammer casing 2 is below the lower end side opening portion 12a of the outer casing 1 The hammer casing 2 is provided with sealing means (bellows cylinders) 5A and 5B that project outside and seal the upper end opening 11a and the lower end opening 12a from the outside. 21 is hard In addition, a drive hammer 22 that strikes the knocking block 21 by free-fall and a lifting mechanism 6 that lifts the dropped drive hammer 22 and releases it at a predetermined height are built in the lower casing 1. A support leg 13 for maintaining the entire apparatus at the bottom in an upright posture is integrally formed, and the suspension support member 3 is provided with a stopper 30 located inside the outer casing 1, and when the apparatus is suspended via the stopper 30. While the outer casing 1 is supported by the suspension support member 3, the tip of the penetrating shaft 4 contacts the hole bottom Hb in a relaxed state of the cable body W when the bottom is settled, and the penetrating shaft 4 is connected to the hole bottom ground ( The support layer is configured to measure the support strength of the hole bottom ground Gh from the number of times the drive hammer 22 is struck to penetrate the Gh to a predetermined depth.

  According to a second aspect of the present invention, in the pile hole penetration test apparatus M according to the first aspect, the sealing means on the upper end side opening portion 11a side of the outer casing 1 is a peripheral portion of the upper end side opening portion 11a and a suspension member. 3 and a bellows cylinder 5A that extends and contracts and allows the suspension member 3 to move up and down through the upper end opening 11a.

  According to a third aspect of the present invention, in the pile hole penetration test apparatus M according to the first or second aspect, the sealing means on the lower end side opening 12a side of the outer casing 1 penetrates the peripheral portion of the lower end side opening 12a. The bellows cylinder 5B is fixed between the middle portion of the shaft 4 and extends and contracts to allow the penetrating shaft 4 to move up and down through the lower end opening 12a.

  According to a fourth aspect of the present invention, in the penetration test apparatus M for pile holes according to any one of the first to third aspects, as the sealing means for the lower end side opening 12a, the elevating space of the hammer casing 2 at the lower end of the outer casing 1 is provided. An accumulator chamber 15 of high internal pressure isolated from 10 is provided, and the penetrating shaft 4 inserts packings (packing members) 16, 17 through the lower end side opening 12 a penetrating the ceiling portion 15 a and the bottom plate portion 15 b of the accumulator chamber 15. It is set as the structure formed by airtightly passing through.

A fifth aspect of the present invention, the pile hole for penetration testing device M of the claims 1, as the sealing means of the lower end opening side of the outer casing, lifting space 10 of the hammer casing 2 to the lower end of the outer casing 1 An accumulator chamber 15 of high internal pressure isolated from the accumulator chamber 15 is provided, and the penetration shaft 4 passes through packings (packing members) 16 and 17 through the lower end side opening 12a penetrating the ceiling portion 15a and the bottom plate portion 15b of the accumulator chamber 15. The lower end of the accumulator 15 is fixed between the outer periphery of the lower end of the accumulator 15 (the mounting flange 17b of the packing member 17) and the intermediate portion of the penetrating shaft 4, and the lower end of the accumulator 15 is expanded and contracted. The structure is composed of a bellows cylinder 5B that allows the penetrating shaft 4 to move up and down through the side opening 12a.

  According to a sixth aspect of the present invention, in the pile hole penetration test apparatus M according to any one of the first to fifth aspects, the lifting mechanism 6 has a clamp portion (clamp provided at the tip of the piston rod 61a protruding downward from the hydraulic cylinder 61. Arm) 63, 63 holds the drive hammer 22, lifts the drive hammer 22 by the shortening operation of the piston rod 61a, and releases the hydraulic hammer 61 from the outside to the hydraulic cylinder 61. In the middle, the double pipe type expansion and contraction pipes 7 and 7 are interposed in the supply / discharge path between the inner upper portion of the outer casing 1 and the upper end portion of the hammer casing 2.

  A seventh aspect of the present invention is the pile hole penetration test apparatus M according to any one of the first to sixth aspects, further comprising an encoder 8 for measuring the descending amount of the hammer casing 2 at the upper part in the outer casing 1. It is said.

  In the pile construction management method according to the invention of claim 8, after forming a pile hole H of a predetermined depth in the ground G, before the pile (cast-in-place pile P1, ready-made pile P2) is built in the pile hole H, The penetration test device M for pile holes according to any one of claims 1 to 7 is suspended by a cable body W, inserted into the pile hole H and allowed to settle, and then penetrated into contact with the hole bottom Hb. The support strength of the hole bottom ground Gh is determined from the number of hits of the drive hammer 22 required for the shaft 4 to penetrate into the ground to a predetermined depth, and a pile is built in the pile hole H when the support strength is a predetermined value or more. It is characterized by.

   Next, effects of the present invention will be described with reference numerals in the drawings. First, according to the penetration test apparatus M for a pile hole according to the invention of claim 1, before the pile (cast-in-place pile P1, ready-made pile P2) is built into the pile hole H drilled in the ground G, this pile hole When the penetration test apparatus M is suspended by a cable body (wire) W, inserted into the pile hole H and grounded, the outer casing 1 is held upright by the support legs 13, and the cable body W is relaxed. As a result, the internal hammer casing 2 can be lowered, and the tip of the penetrating shaft 4 can be brought into contact with the hole bottom Hb. By operating the pile hole penetrating test device M in this state, the penetrating shaft 4 Based on the number of times the drive hammer 22 is struck to penetrate the ground (support layer) Gh to a predetermined depth, the support strength of the hole bottom ground Gh can be measured very easily and reliably as an actual measurement value (N value).

  Moreover, in this pile hole penetration test apparatus M, the suspension support member 3 to be engaged with the cable body W is fixed to the upper end portion of the hammer casing 2 through the upper end opening 11a of the outer casing 1, and the suspension support member 3 Since the stopper 30 is fixedly located inside the outer casing 1, when suspended by the cable body W, the outer casing 1 is also suspended by the suspension member 3 via the stopper 30. Accordingly, the hammer casing 2 is automatically arranged at the upper limit position in the outer casing 1. Therefore, in the case of this penetration test apparatus M for pile holes, there is a special drive mechanism and work operation for lifting the hammer casing 2 after the previous test to the upper limit position in the outer casing 1 in the next penetration test. It is unnecessary, and it is structurally simple, so that the manufacturing cost is reduced and the workability of the penetration test is improved. Moreover, since the lower end side opening part 12a and the lower end side opening part 12a of the outer casing 1 can be sealed with respect to the outside by the sealing means (bellows cylinders) 5A, 5B, mud sand, gravel, mud water in the pile hole H, It is possible to reliably prevent the stabilizing liquid, rooting liquid, etc. injected into the hole from entering the outer casing 1 and hindering the lifting / lowering operation of the hammer casing 2, thereby ensuring the reliability of the measured value and the penetration test apparatus. It is possible to prevent a decrease in durability.

  According to the invention of claim 2, since the sealing means on the upper end side opening portion 11a side of the outer casing 1 is made of the expandable / contractible bellows cylinder 5A, the vertical movement of the suspension member 3 is not hindered. It is possible to prevent intrusion of mud sand, sand gravel, mud water, stabilizing liquid and the like from the upper end side opening 11a into the outer casing 1.

  According to the invention of claim 3, since the sealing means on the lower end side opening 11a side of the outer casing 1 is made of an expandable / contractible bellows cylinder 5B, the vertical movement of the penetrating shaft 4 is hardly given resistance. Intrusion of mud sand, gravel, mud water, stabilizing liquid, etc., from the lower end side opening 12a into the outer casing 1 can be reliably prevented.

  According to the invention of claim 4, since the high internal pressure accumulation chamber 15 is provided at the lower end portion of the outer casing 1 as a sealing means for the lower end side opening portion 12a, the lower end side opening portion 12a through which the penetration shaft 4 is inserted. Intrusion of mud sand, mud water, stabilizing liquid, root-setting liquid, etc. into the outer casing 1 from is prevented by the high pressure in the accumulator chamber 15.

  According to the invention of claim 5, the bellows cylinder 5B fixed between the outer peripheral portion of the lower end of the accumulator 15 (the mounting flange portion 17b of the packing member 17) and the intermediate portion of the penetrating shaft 4, There is an advantage that the solid particles in the hole H and the solid particles in the muddy water can be prevented from entering the lower end side opening 12a, so that the sealing failure due to the biting of the solid particles into the packing can be surely prevented.

  According to the invention of claim 6, in the supply / discharge path of the hydraulic oil to the hydraulic cylinder 61 of the lifting mechanism 6, the double pipe type is provided in the supply / discharge path between the inner upper part of the outer casing 1 and the upper end part of the hammer casing 2. The expansion and contraction pipes 7 and 7 are interposed, and the expansion and contraction pipes 7 and 7 expand and contract following the up-and-down displacement of the hammer casing 2 in the outer casing 1, so that the hydraulic oil 61 is always supplied and discharged smoothly. In addition, there is an advantage that the durability of the movable part is greatly improved as compared with the case where the movable part of the supply / discharge path accompanying the raising / lowering of the hammer casing 2 is constituted by a slackened hydraulic hose.

  According to the invention of claim 7, since the encoder 8 for measuring the descending amount of the hammer casing 2 is provided at the upper part in the outer casing 1, the amount of penetration of the penetrating shaft 4 into the hole bottom Hb due to the knocking of the knocking block 21 is accurately determined. Can be caught.

  According to the pile construction management method according to the invention of claim 8, after the pile hole H having a predetermined depth is formed in the ground G, before the pile (the cast-in-place pile P1 and the ready-made pile P2) is built in the pile hole H Then, the pile hole penetration test device M according to any one of claims 1 to 7 is suspended by a cable body W, inserted into the pile hole H and then settled, and then contacted with the hole bottom Hb. The support strength of the hole bottom ground Gh is determined from the number of hits of the drive hammer 22 required for the penetrating shaft 4 to penetrate into the ground to a predetermined depth, and if the support strength is equal to or greater than a predetermined value, it is determined that it can be built. A pile can be built in this pile hole H, and pile construction can be completed efficiently. On the other hand, if the support strength is less than the predetermined value, it will be impossible to embed it. Therefore, excavate deeper, or backfill the pile hole H and newly drill at a different position. This determination may be made. Therefore, it is possible to avoid a situation in which a great amount of labor, time and cost are spent to redo the pile erection work, as in the case where a lack of support strength is found in a loading test after completion of the pile work in the past. In addition, since the management can be performed with the international standard N value, there is an advantage that high reliability evaluation of the measured value can be obtained.

It is a perspective view of the whole penetration test device for pile holes concerning a first embodiment of the present invention. The inside of the penetration test apparatus for pile holes is shown, (a) is a longitudinal front view, and (b) is a cross-sectional view taken along line XX in (a). The inside of the hammer casing in the penetration test device for the same pile hole is shown, (a) is the state where the drive hammer in the dropping position is gripped by the clamp part of the lifting mechanism, (b) is lifted to the upper limit position by the lifting mechanism FIG. 6 is a longitudinal front view of a state where the drive hammer is opened. The lifting mechanism in the hammer casing is shown, (a) is a partially cutaway side view, (b) is a front view of the lower clamp part, and (c) is a bottom view of the clamp arm. The operation of the lifting mechanism is shown, (a) is a side view when the drive hammer is lifted, and (b) is a side view when the drive hammer is released. The penetration test operation by the penetration test device for the pile hole is shown, (a) the state where the penetration test device for the pile hole is settled in the pile hole, (b) is the state where the penetration shaft is penetrated into the pile bottom ground, FIG. It is a schematic longitudinal cross-sectional view which shows the pile foundation formation by the Kelly bar type earth drill method using the penetration test apparatus for the said pile holes in order of the process of (a)-(k). It is a schematic longitudinal cross-sectional view which shows the pile foundation formation by the all casing construction method using the penetration test apparatus for the said pile holes in order of the process of (a)-(h). It is a schematic longitudinal cross-sectional view which shows the pile foundation formation by the pre-boring method using the penetration test apparatus for the same pile hole in order of the process of (a)-(g). The other structural example of the penetration test apparatus for pile holes of this invention is shown, (a) is a longitudinal cross-sectional view of the lower part of the penetration test apparatus for pile holes which concerns on 2nd embodiment, (b) concerns on 3rd embodiment. It is a longitudinal cross-sectional view of the lower part of the penetration test apparatus for pile holes.

  Hereinafter, embodiments of a pile hole excavating apparatus and a pile construction management method according to the present invention will be specifically described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the component which is common in 1st-3rd embodiment.

  As shown in FIGS. 1 and 2, the pile hole penetration test apparatus M according to the first embodiment includes a cylindrical hammer casing 2 mounted in a vertically cylindrical outer casing 1 so as to be movable up and down. The rod-shaped suspension support member 3 protrudes vertically from the upper end opening 11a provided in the upper taper cap 11, and the penetrating shaft 4 protrudes vertically from the lower end opening 12a provided in the lower taper cap 12. In addition, between the cylindrical port portion 11b around the upper end side opening portion 11a and the upper portion of the suspension member 3, and between the cylindrical port portion 12b around the lower end side opening portion 12a and the intermediate portion of the penetrating shaft 4 Bellows cylinders 5A and 5B are mounted as sealing means for sealing the upper end side opening portion 11a and the lower end side opening portion 12a to the outside. Further, at the lower part of the outer casing 1, a support leg 13 in which upper and lower large-diameter pipe rings 13 a and 13 b are connected by a plurality of (four in the figure) pipe columns 13 c, and the lower pipe ring 13 b is connected to the outer casing 1. It is fixed via brackets 13d arranged radially on the upper side so as to be lower than the lower end.

  In this pile hole penetration test apparatus M, a hook (not shown) such as a wire hanging from a boom of a crawler crane or the like is passed through a suspension fitting 31 connected to the upper end of the suspension member 3 with respect to a hook Ho at the lower end. By hanging the hanging ring 32 made of wire, the entire device is suspended to enter / exit the pile hole (not shown), while the entire device maintains an upright posture by the support leg 13 when the pile hole is settled. ing.

  As shown in FIG. 2A, the suspension member 3 is pivotally connected to the upper end of the hammer casing 2 via a pivot pin 33, but is attached to an intermediate portion located inside the outer casing 1. A circular flange-shaped stopper 30 is provided, and the outer casing 1 when the apparatus is suspended is supported on the inner side of the upper taper cap 11 via the stopper 30. And in this apparatus suspended state, the front-end | tip of the insertion axis | 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 13, ie, the lower side pipe ring 13b. As shown in FIGS. 2 (a) and 2 (b), guide rails 13 composed of two parallel strips along the vertical direction are provided on the inner periphery of the outer casing 1 at a plurality of locations in the circumferential direction (4 in the figure). The fitting keys 23 that are formed at equal positions and project from the upper and lower portions of the outer periphery of the hammer casing 2 are slidably fitted to the guide rails 13.

  Further, a mounting plate 14 is fixed on the inner upper portion of the outer casing 1, and a hydraulic cylinder 61 (described later) in the hammer casing 2 is provided between the lower surface side of the mounting plate 14 and the upper end of the hammer casing 2. 3), two double-pipe type expansion and contraction pipes 7 and 7 constituting a supply and discharge path for hydraulic oil are interposed. Further, an encoder 8 for measuring the lowering amount of the hammer casing 2 with respect to the outer casing 1 is attached to the lower surface side of the mounting plate 14, and a measurement cord 8 a extending from the encoder 8 is fixed to the upper end of the hammer casing 2. Has been. Between the attachment plate 14 of the outer casing 1 and the upper taper cap 11, a hydraulic hose h connected to the upper end side of each expansion pipe 7 and an electrical wiring e for the encoder 8 are disposed. The upper taper cap 11 is provided with hose connecting cylindrical shaft portions 11c projecting upward on both sides of the upper end opening portion 11a, and an external hydraulic pressure supply source (not shown) is provided on both cylindrical shaft portions 11c and 11c. Are connected via an adapter a, and one of the hydraulic hoses h2 has an electrical wiring e for the encoder 8 inserted between the double structures. A through hole 14a is formed in the center of the mounting plate 14, and the suspension support member 3 passes through the through hole 14a.

  The upper and lower bellows cylinders 5A and 5B 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. As the hammer casing 2 moves up and down in the outer casing 1, The other side contracts in response to the extension of one side, but both are set to substantially the same shape and size, so that the gap between the inner periphery of the outer casing 1 and the outer periphery of the hammer casing 2 passes through. By the air movement, the increase in the internal volume due to the extension of one is offset by the decrease in the internal volume due to the contraction of the other. Both the bellows cylinders 5A and 5B are formed into a long and narrow cylindrical shape when extended, but in order to prevent being crushed by water pressure, a metal ring 51 for shape retention is provided on the inner side for each ridge (valley). Is fitted. Further, both end portions of the bellows cylinders 5A and 5B are liquid-tight with respect to the cylinder port portions 11b and 12b of the upper and lower taper caps 11 and 12 and the suspension member 3 and the penetration shaft 4 by a fastener 52 such as a fastening band. It is fastened.

  As shown in FIG. 3, the hammer casing 2 has a knocking block 21 fixed to the lower end, a drive hammer 22 that strikes the knocking block 21 by free fall inside, and a drive hammer 22 that has been dropped is lifted to a predetermined height. And a lifting mechanism 6 which is released at the bottom, and the penetrating shaft 4 is fixed to the lower surface of the knocking block 21 by a disc portion 4a at the upper end. 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.

  As shown in FIGS. 4A to 4C, the lifting mechanism 6 in the hammer casing 2 is provided with a pair of clamps on a downward bifurcated pivot support frame 62 fixed to the distal end portion of the telescopic rod 61 a of the hydraulic cylinder 61. The arms 63, 63 are pivotally mounted in a vertical plane via pivot pins 62a each composed of a bolt, and are opened downward at the lower end outer peripheral portion of the hydraulic cylinder 61 and the inner peripheral lower portion is lowered. A short cylindrical grip releasing cylinder 64 which is an annular tapered surface 64a that expands toward the bottom is fixed. In addition, each clamp arm 63 is integrally formed with an inwardly concave horizontal arcuate locking portion 63a at each lower end, and the inner peripheral lower portion of each locking portion 63a becomes a tapered surface 63b that expands downward. The upper side of the inner periphery forms a curved claw 63c, and the outer surface of the upper end is an upwardly inclined surface 63d. The clamp arms 63 and 63 are urged in the closing direction in which the locking portions 63a and 63a approach each other by a coil spring 65 interposed between the opposing upper ends. Note that the two hydraulic hoses h and h led out from the hydraulic cylinder 61 of the lifting mechanism 6 are each connected to the upper expansion pipe 7. On the other hand, as shown in FIGS. 3 and 5, a locking shaft 22 a having a top portion with a large truncated cone portion 22 b is implanted in the center of the upper surface of the drive hammer 22.

  In this lifting mechanism 6, when the drive hammer 22 is in the dropping position in the hammer casing 2, the piston rod 61 a of the hydraulic cylinder 61 is extended, as shown in FIGS. 3 (a) and 5 (a), The tapered surfaces 63b, 63b of the locking portions 63a, 63a of both the clamp arms 63, 63 are in contact with the truncated cone portion 22b of the locking shaft 22a of the drive hammer 22, and both the clamp arms 63, 63 are coiled by an inclination inducing action. By opening the spring 65 against the bias of the spring 65, both the curved claw portions 63c and 63c are engaged with the lower side of the truncated cone portion 22b. Then, the piston rod 61a is contracted in this engaged state to grip and lift the drive hammer 2, but when the piston rod 61a reaches the upper limit position, as shown in FIG. The inclined surfaces 63d and 63d at the upper ends of the clamp arms 63 and 63 come into contact with the tapered surface 64b of the grip release cylinder 64, and both the clamp arms 63 and 63 are forced to resist the bias of the coil spring 65 by the inclination inducing action. Therefore, the released drive hammer 22 falls freely and strikes the knocking block 21 at the bottom end of the hammer casing 2. Therefore, when the outer casing 1 is bottomed, the hammer casing 2 is moved downward by the striking force of the drive hammer 22, and the penetrating shaft 4 is lowered accordingly, while the bellows cylinder 5B is extended, while the upper bellows cylinder is extended. 5A conversely contracts.

  The pile hole penetration test apparatus M having the above-described structure is provided with a pile hole H having a predetermined depth in the ground G as shown in FIG. 6 (a) in pile construction by an earth drill method, an all casing method, a pre-boring method or the like. Then, before the pile is built in the pile hole H, it is suspended by a wire hanging from a boom of a crawler crane, inserted into the pile hole H, and then bottomed, and driven in this bottomed state. Measure the ground support strength. In this bottomed state, the suspended wire is relaxed to perform a measurement test. As shown in the drawing, the support leg 13 contacts the hole bottom Hb, so that the entire apparatus is self-supporting and maintains an upright posture. Since the hammer casing 2 can freely descend by its relaxation, the tip of the insertion shaft 4 is surely brought into contact with the hole bottom Hb.

  In the measurement test, as described above, by driving the lifting mechanism 6 in the hammer casing 2, the drive hammer 22 is held and lifted by the clamp arms 63 and 63 as shown in FIG. In the upper limit position, both clamp arms 63 and 63 are opened by the grip release cylinder 64 to release the drive hammer 14, and the knocking block 12 at the lower end is hit with the drive hammer 14 that falls freely. As shown in FIG. 6 (b), the penetration shaft 4 penetrates into the ground of the pile bottom Hb by the hammer casing 3 as shown in FIG. 6 (b), so that the penetration shaft 13 is repeated by repeating the hammering operation thereafter. Measures the number of impacts required to penetrate from the hole bottom Hb to a predetermined depth, and determines 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. As shown in FIG. 6B, as the penetration of the penetration shaft 4 into the ground G deepens, the lower bellows cylinder 5B expands, while the upper bellows cylinder 5A contracts and expands and contracts. The pipes 7 and 7 are also extended.

  The number of hits (N value) of the drive hammer 22 is counted by a hydraulic drive control device (not shown) on the ground side that controls the operation of the hydraulic cylinder 61 of the lifting mechanism 6, and the amount of penetration of the penetration shaft 4 into the hole bottom ground is the hammer. The amount of descent of the casing 2 is measured by the encoder 8. Then, the measurement signal from the encoder 8 is sent to an automatic measuring device (not shown) on the ground through the electric wiring e, and the amount of subsidence per one 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, the drive hammer 22 having a mass of 63.5 ± 0.5 kg is freely dropped by 76 ± 1 cm to hit the knocking block 21, and the outer diameter is 51 ± 1 mm and the inner diameter is 35 ±. Since the number of impacts required for the 1 mm penetration shaft 4 to penetrate 30 cm into the ground is expressed as an N value, even in this pile hole penetration test apparatus M, if the support strength is grasped as an N value according to the standard penetration test, Good.

  Thus, if the measured support strength of the pile bottom ground is equal to or higher than a predetermined value, it is determined that the pile can be built, and the pile hole penetration test device M is lifted with a wire and pulled out from the pile hole H. The pile construction may be completed by installing a cast-in-place pile or an existing pile in the pile hole H by a process according to the pile construction method. On the other hand, if the support strength is less than the predetermined value, it will be impossible to embed it. Therefore, excavate deeper, or backfill the pile hole H and newly drill at a different position. This determination may be made. Therefore, it is possible to avoid a situation in which a great amount of labor, time and cost are spent to redo the pile erection work, as in the case where a lack of support strength is found in a loading test after completion of the pile work in the past.

  When the present invention is applied to the construction of cast-in-place piles by the kelly bar type earth drill method, as shown in FIG. 7, (a) the upper layer soft layer Gs is formed by the shaft excavation bucket B1 connected to the kelly bar K of the earth drill machine. Excavation and earth removal, (b) press-fit the stunt pipe Ps into the excavation hole, and (c) excavate with a small diameter shaft excavation bucket B2 while injecting a stable liquid Ls such as bentonite liquid into the pile -Draining and (d) forming a pile hole H having a depth reaching the hard support layer Gh in the assumed underground depth. Then, (e) the pile hole penetration test device M suspended by the wire W using the boom of the earth drill machine is inserted into the pile hole H after the shaft excavation bucket B2 is extracted, and the hole bottom Hb is inserted. If the support strength of the above-mentioned pile bottom ground is measured in the relaxed state of the wire W and the support strength is equal to or greater than a predetermined value, (f) the inside of the pile hole H after extraction of the penetration test apparatus M Reinforcement rod Fc is built in, (g) Tremy tube Tp is inserted inside reinforcement rod Fc, (h) Slime S is discharged by introduction of air A, (i) The construction of the cast-in-place pile P1 is completed by the procedure of pulling out the tremy pipe Tp with the launch and (k) finally pulling out the stunt pipe Ps.

  In addition, although illustration is abbreviate | omitted, when the cast-in-place pile P1 is built after expanding the bottom part with a bottom expansion bucket after formation of the pile hole H as a bottom expansion pile construction, by the penetration test apparatus M of the said process (e). After measuring the support strength of the pile bottom ground, the pile bottom is expanded with the expanded bucket, or the pile bottom is expanded with the expanded bucket following the formation of the pile hole H in the step (d), and then the penetration test apparatus M Measurement may be performed according to the above.

  When the present invention is applied to the construction of cast-in-place piles by the all-casing method, as shown in FIG. 8, (a) a steel device in which the tubing device TM is arranged on the ground at the drilling position and suspended by the wire W of the crane The casing tube CT is set in the tubing device TM, and (b) the casing tube CT is pressed into the ground while swinging and / or rotating all around, and the inside thereof is excavated and discharged with a hammer grab HG. (C) By adding the casing tube CT and continuing excavation and soil removal, a pile hole H having a depth reaching the support layer Gh in the deep underground is formed, and a hammer grab HG and a sedimentation bucket (not shown) ), And (d) the pile hole penetration test device M suspended by the wire W of the crane is inserted into the casing tube CT and the hole bottom Hb is inserted. It is bottom landing, measures the strength of supporting the pile bottom ground earlier in relaxed state of the wire W. If the supporting strength is equal to or greater than a predetermined value, (e) a reinforcing bar rod Fc is built in the casing tube CT after the penetration test apparatus M is pulled out, and (f) a tremy tube is placed inside the reinforcing rod rod Fc. (G) Pulling out the casing tube CT and the tremmy tube Tp with the launch while placing the raw concrete C, (h) Finally, the construction of the cast-in-place pile P1 is completed.

  Further, when the present invention is applied to the construction of a ready-made pile by the pre-boring method, as shown in FIG. 9, (a) a screw rod is attached to an auger machine A that moves up and down along a leader (not shown) such as a three-point pile driver. After attaching Rs and lowering the screw rod Rs while rotating, the ground is excavated, and (b) after forming a pile hole H having a depth reaching the support layer Gh in the deep underground, (c) While pulling up the screw rod Rs, a root-setting liquid Ls such as soil cement is injected. (D) Subsequently, the hole periphery fixing liquid Lf is injected up to the upper part of the pile hole H, and the screw rod Rs is extracted. ) Pile hole penetration test device M suspended by wire W such as the above three-point pile driver or another crane is inserted into the casing tube CT and settled on the hole bottom Hb. Support strength of the pile bottom ground is measured. If the supporting strength is equal to or greater than a predetermined value, (f) a pre-made pile P2 such as a PHC pile or a RC pile is connected to the auger machine A via a connecting rod Rj, and this pre-made pile P2 is connected to the pile hole H. Insert (G) to the bottom of the pile hole H to complete the construction of the ready-made pile P2.

  The pile hole penetration test apparatus M and the pile construction management method of the present invention are not limited to the Keriba-type earth drill method, all-casing method, and pre-boring method exemplified in FIGS. Applicable to all methods of pile construction in which cast-in-place piles P1 and ready-made piles P2 are built in H.

  As described above, according to the pile hole penetration test apparatus M and the pile construction management method of the present invention, based on the number of hits of the drive hammer 22 required for the penetration shaft 4 to penetrate the hole bottom ground to a predetermined depth, The support strength of the hole bottom Hb can be measured very simply and reliably as an actual measurement value (N value). Moreover, in this penetration test apparatus M for pile holes, the upper opening 11a through which the suspension member 3 of the outer casing 1 is inserted and the lower opening 12a through which the penetration shaft 4 is inserted are externally formed by the bellows cylinders 5A and 5B. Therefore, mud sand, sand gravel, mud water, stabilization liquid injected into the hole, rooting liquid, etc. enter the outer casing 1 and hinder the lifting and lowering operation of the hammer casing 2. Can be reliably avoided, so that the reliability of the measured value can be ensured and the durability of the apparatus can be prevented from being lowered. Furthermore, since this pile hole penetration test device M can use the main part of the standard penetration test device that has been widely used for determining the N value of the ground, the facility cost can be reduced and the international standard N Highly reliable evaluation of measured values can be obtained because management by value is possible.

  Moreover, in this penetration test apparatus M for pile holes, when it is hung with a cable body such as a wire W, inserted into the pile hole H, and grounded, the outer casing 1 is fixed in an upright state by the support legs 13. By relaxing the suspended cable body, the internal hammer casing 2 can be lowered, the tip of the penetrating shaft 4 can automatically contact the hole bottom Hb, and measurement can be started. The hammer casing 2 is automatically returned to the upper standby position, that is, the upper limit position in the outer casing 1 by lifting it up, so that separate drive mechanisms for switching the casing 2 to the measurement start position and the upper standby position are required. Not only that, the structure is simplified, the operation reliability is improved, and the production cost can be reduced.

  Further, in the case of the illustrated pile hole penetration test apparatus M, between the inside upper portion (mounting plate 14) of the outer casing 1 and the upper end portion of the hammer casing 2 in the hydraulic oil supply / discharge path of the lifting mechanism 6 to the hydraulic cylinder 61. Since the double-pipe type expansion and contraction pipes 7 and 7 are interposed in the supply / discharge path, the extension and contraction pipes 7 and 7 expand and contract following the up-and-down displacement of the hammer casing 2 in the outer casing 1. Compared with a general configuration in which the hydraulic cylinder 61 can always ensure the smooth supply and discharge of hydraulic oil, and the movable portion of the supply and discharge passage accompanying the lifting and lowering of the hammer casing 2 is constituted by a hydraulic hose. Since there is no fatigue deterioration due to repeated bending and stretching like a hose, there is an advantage that the durability of the movable part is greatly improved. Furthermore, in the embodiment, since the encoder 8 that measures the descending amount of the hammer casing 2 is provided in the upper part of the outer casing 1, the amount of penetration of the penetration shaft 4 into the hole bottom Hb due to the knocking of the knocking block 21 can be accurately captured. Can do.

  Thus, in the penetration test apparatus M for pile holes of the present invention, the bellows cylinders 5A and 5B are used in the embodiment as sealing means for the upper end side opening 11a and the lower end side opening 12a of the outer casing 1. In addition to packings such as metal seals, mechanical seals, and O-rings, other various sealing mechanisms generally used for sealing sliding portions can be employed. However, in the bellows cylinder that can be expanded and contracted as illustrated, mud sand, gravel, mud water, stabilizing liquid, rooting liquid into the outer casing 1 is hardly given resistance to the vertical movement of the suspension member 3 and the penetrating shaft. There is an advantage that it is possible to reliably prevent the entry of such as. In the embodiment, the bellows cylinders 5A and 5B are illustrated as being generally the same diameter and are elongated when extended. For example, the bellows cylinders 5A and 5B are conical bellows whose diameter increases toward the proximal end. The bellows form can also be adopted.

  Further, as the sealing means, for example, the liquid component in the pile hole H enters the outer casing 1 as in the pile hole penetration test apparatus M according to the second embodiment of the present invention shown in FIG. The internal pressure can also be used to more reliably eliminate this. That is, in this pile hole penetration test apparatus M, an accumulator chamber 15 is provided at the lower end of the outer casing 1 so as to be isolated from the elevating space 10 of the hammer casing 2, and the accumulator chamber 15 is accumulated by sealing with compressed air. ing. The penetration shaft 4 at the lower end of the hammer casing 2 is inserted through the packing members 16 and 17 in an airtight manner into the lower end side opening portion 12a opened in the ceiling portion 15a and the bottom plate portion 15b of the accumulation chamber 15.

  The accumulation chamber 15 is bolted to the outer casing body 1a as an independent lower end member 1b. Further, the upper packing member 16 is formed of a thick circular annular plate at the center side, and a plurality of seal rings are fitted on the inner periphery. The upper packing member 16 is disposed on the upper side of the ceiling portion 15a of the accumulator 15 and is placed on the lower side. The mounting ring 18 is bolted together. On the other hand, the lower packing member 17 has a flange portion 17b integrally formed on the outer periphery of a cylindrical portion 17a in which a plurality of seal rings are fitted on the inner periphery of the lower side. The flange portion 17b is bolted to the bottom plate portion 15b via the cushion ring 19 in a state of being inserted into the opening portion 15c of the bottom plate portion 15b.

  In this configuration, in addition to the sealing of the lower end side opening 12a through which the penetrating shaft 4 is inserted by the packing members 16 and 17, the inside of the accumulator 15 is maintained at a high pressure, and therefore the outer casing from the lower end side opening 12a. Intrusion of mud sand, mud water, stabilizing liquid, root-setting liquid, etc. into 1 is prevented by the high pressure in the accumulation chamber 15.

  Further, as the sealing means, for example, the bellows cylinder 5B as described above is placed in the same accumulator chamber 15 as in the pile hole penetration test apparatus M according to the third embodiment of the present invention shown in FIG. Can be combined. In this case, the bellows cylinder 5B is substantially the same as that used in the first embodiment described above, and the upper end portion is on the outer periphery of the lower end outer peripheral portion of the accumulation chamber 15, that is, on the outer periphery of the mounting flange portion 17b of the packing member 17. A lower end portion is fixed to an intermediate portion of the penetrating shaft 4 via a fastener 52. According to the configuration of the third embodiment, the bellows cylinder 5B can eliminate the intrusion of solid particles in the pile hole H or the solid particles in the muddy water into the lower end side opening 12a, and thus the solid particles to the packing can be removed. There is an advantage that sealing destruction due to biting can be surely prevented.

  In addition, although the structure which provided the accumulation chamber 15 in the lower end of the outer casing main body 1 was illustrated in the above-mentioned 2nd and 3rd embodiment, in this invention, as a sealing means of the upper end side opening part 11a of the outer casing 1 However, it is possible to provide the same accumulator chamber 15 or to further combine the accumulator chamber 15 and the bellows cylinder 5B.

  As the suspension member 3, a rod shaft-shaped member is exemplified in the embodiment, but a wire, a pipe material, or the like can also be adopted, and an engagement structure on the upper end side with respect to a cable body such as a wire W to be suspended is also an embodiment. Various structures other than can be adopted. Further, in the embodiment, the stopper 30 provided on the suspension member 3 is configured to come into contact with the inner upper end of the outer casing 1, that is, the central lower surface of the upper taper cap 11. It is good also as a structure which provides the receiving part like 14 and contacts the outer casing 1 by contact | abutting to this receiving part from the lower side. In addition, the illustrated wire W is generally used as the cable body that suspends the penetration test apparatus M via the suspension support member 3, but other cable bodies such as a chain can also be used.

  As the support leg 13, in the embodiment, the upper and lower pipe rings 13 a and 13 b and the plurality of pipe support pillars 13 c are integrated, but three or more independent legs are provided at the lower peripheral surface of the outer casing 1. Various forms that can hold the entire apparatus in an upright state by grounding, such as a form in which it is arranged and fixed, can be employed.

  Further, the lifting / lowering guide mechanism of the hammer casing 2 has a function of preventing the rotation of the hammer casing 2 in the outer casing 1 in order to prevent twisting of the hydraulic supply / discharge passage and the electric circuit derived from the hammer casing 2. What is necessary is not to be limited to the structure composed of the guide rail 13 on the outer casing 1 side and the fitting key 23 on the hammer casing 2 side as illustrated, but provided with annular guide plates at a plurality of upper and lower locations in the outer casing 1 Various other structures such as a structure in which a vertically extending ridge provided on the outer periphery of the hammer casing 2 is fitted in a recess on the inner periphery of the guide plate, a structure in which the other guide roller is in rolling contact with one guide rail, etc. A guide structure can be adopted. In addition, the detailed configuration of the penetration test apparatus M for pile holes of the present invention can be variously modified in addition to the embodiment.

DESCRIPTION OF SYMBOLS 1 Outer casing 11a Upper end side opening part 12a Lower end side opening part 13 Support leg 14 Mounting plate (inner upper part of an outer casing)
DESCRIPTION OF SYMBOLS 15 Accumulation chamber 15a Ceiling part 15b Bottom plate part 16, 17 Packing member 2 Hammer casing 21 Knocking block 22 Drive hammer 3 Suspension support member 30 Stopper 4 Penetrating shaft 5A, 5B Bellows cylinder (sealing means)
6 Lifting mechanism 61 Hydraulic cylinder 61a Piston rod 63 Clamp arm (clamp part)
7 Expandable piping 8 Encoder G Ground Gh Support layer (hole bottom ground)
H Pile hole Hb Pile bottom M Penetration test device for pile hole P1 Cast-in-place pile P2 Ready-made pile W Wire (Rope)

Claims (8)

It is a penetrating test device for a suspended pile hole that suspends the entire device with a cable body and inserts it into the pile hole and settles down,
A cylindrical hammer casing is loaded in the vertical cylindrical outer casing so as to be movable up and down, and a suspension support member to be engaged with the cable body is fixed to the upper end portion of the hammer casing through the upper end side opening of the outer casing, A penetrating shaft that protrudes concentrically downward from the lower end of the hammer casing projects outward from the lower end opening of the outer casing and seals the upper end opening and the lower end opening from the outside. A sealing means,
The hammer casing has a knocking block fixed to the lower end, a drive hammer that strikes the knocking block by free fall, and a lifting mechanism that lifts the dropped drive hammer and releases it at a predetermined height,
A support leg for keeping the entire apparatus in an upright posture is integrally formed at the lower part of the outer casing, and the suspension member is provided with a stopper located inside the outer casing. While the outer casing at the time of suspension is supported by the suspension support member,
In the relaxed state of the cable body at the time of landing, the tip of the penetration shaft comes into contact with the bottom of the hole, and the number of hits of the drive hammer required for the penetration shaft to penetrate into the hole bottom ground to a predetermined depth Pile hole penetration testing device configured to measure support strength.   The sealing means on the upper end side opening portion side of the outer casing is fastened between the periphery of the upper end side opening portion and the intermediate portion of the suspension member, and is expanded and contracted so that the upper end side opening portion is formed. The pile hole penetration test apparatus according to claim 1, comprising a bellows cylinder that allows vertical movement of the suspended suspension member.   The sealing means on the lower end side opening portion side of the outer casing is fixed between a peripheral portion of the lower end side opening portion and an intermediate portion of the penetrating shaft, and expands and contracts to pass through the lower end side opening portion. The pile hole penetration test apparatus according to claim 1 or 2, comprising a bellows cylinder allowing vertical movement of the penetration shaft.   As a sealing means for the opening on the lower end side, a high internal pressure accumulation chamber is provided at the lower end portion of the outer casing and is isolated from the lifting / lowering space of the hammer casing, and the lower end side penetrating the ceiling portion and the bottom plate portion of the accumulation chamber The penetration test apparatus for pile holes according to any one of claims 1 to 3, wherein the penetration shaft is inserted through the opening in an airtight manner through a packing. As the sealing means on the lower opening side of the outer casing, a high internal pressure accumulation chamber is provided at the lower end of the outer casing and is isolated from the lifting / lowering space of the hammer casing, and penetrates the ceiling and bottom plate of the accumulation chamber. The penetration shaft is hermetically inserted through the lower end side opening through the packing, and is fixed between the lower end outer peripheral portion of the accumulation chamber and the intermediate portion of the penetration shaft, and is expanded and contracted. The pile hole penetration test apparatus according to claim 1 , comprising a bellows cylinder that allows vertical movement of the penetration shaft through the lower end side opening . The lifting mechanism grips the drive hammer by a clamp portion provided at the tip of a piston rod protruding downward from the hydraulic cylinder, lifts the drive hammer by a shortening operation of the piston rod, and opens the upper limit position.
6. A double pipe type expansion / contraction pipe is interposed in a supply / discharge path between an inner upper part of an outer casing and an upper end part of a hammer casing in a supply / discharge path of hydraulic oil from the outside to the hydraulic cylinder. The penetration test device for pile holes according to any one of the above.   The pile hole excavation device according to any one of claims 1 to 6, further comprising an encoder for measuring a descending amount of the hammer casing at an upper portion in the outer casing.   The pile hole penetration test device according to any one of claims 1 to 7 is suspended by a rope body after the pile hole having a predetermined depth is formed in the ground and before the pile is built into the pile hole. After inserting into the pile hole and bottoming, the support strength of the hole bottom ground is determined from the number of times the drive hammer hits the penetrating shaft in contact with the hole bottom to penetrate the ground to a predetermined depth. A pile construction management method, wherein a pile is built into the pile hole when the strength is equal to or greater than a predetermined value.

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