JP5972494B1 - Penetration testing machine for excavation rod connection and pile construction management method - Google Patents

Abstract

Provided is a means for making it possible to immediately determine the bearing capacity of a hole bottom ground after forming a pile hole in the ground, and to save the trouble of re-implementing pile construction due to insufficient support strength. A penetration tester M1, M2 connected in place of excavation tip members B1, B2, Rh of excavation rods K, Rs. A hammer casing 2 is loaded in an outer casing 1 so as to be movable up and down. A sealing means 4 that projects from the lower end side openings 12a and 12b of the outer casing 1 to the outside and projects from the lower end side openings 12a and 12b to the outside. 5A and 5B are provided, and the connecting portion 9 and 9A are provided at the upper end of the outer casing 1. The hammer casing 2 has a built-in drive hammer 22 that strikes the knocking block 21 at the lower end by free fall and a lifting mechanism 6 that lifts the drive hammer 22 after dropping and then releases it, and is connected to the excavation rod. The penetration shaft 3 whose tip is grounded to H is configured to measure the supporting strength of the hole bottom ground from the number of times the drive hammer 22 is hit to penetrate the hole bottom ground Gh to a predetermined depth. [Selection] Figure 2

Description

  The present invention relates to a penetration testing machine for examining the supporting strength of a hole bottom ground in a pile hole drilled in the ground by an earth drill method, a pre-boring method, and the like, and a pile construction management method using this penetration testing machine.

  Conventionally, the Keriba-type earth drill method has been widely used for the construction of cast-in-place piles. In this construction method, the ground was excavated and discharged by a shaft excavator bucket connected to a kelly bar of an earth drill machine, a stunt pipe was press-fitted into the excavation hole, and a stable liquid such as bentonite liquid was injected and replaced. Excavation and soil removal with a small-diameter shaft excavation bucket to form a pile hole with a depth that reaches the support layer in the assumed underground depth, insert a reinforcing rod and treme tube into this pile hole, and introduce slime by introducing air After discharging, cast-in-place piles are built in the procedure of placing raw concrete and pulling out treme and stunt pipes. 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.

  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 hole bottom ground is sufficient immediately after forming a pile hole in the ground by various methods, and thus due to insufficient support strength. The purpose of this study is to provide a penetration testing machine that makes it possible to save the trouble of re-working pile erection, and a pile construction management method using this penetration testing machine.

  If the means for achieving the above object is shown with reference numerals in the drawings, the invention of claim 1 is the excavation destination of the excavation rod (Keriba K, screw rod Rs) for drilling the pile hole H by rotary excavation. Drilling rod connection penetration test machines M1 and M2 used by connecting to the tip of the excavation rod instead of the members (shaft excavation bucket B1, widened bucket B2, tip rod member Rh), and having a vertical cylindrical outer side A cylindrical hammer casing 2 is loaded in the casing 1 so as to be movable up and down, and a penetrating shaft 3 protruding downward concentrically at the lower end of the hammer casing 2 is provided below the lower end side openings 12a and 12b of the outer casing 1. And is provided with sealing means (bellows cylinder 4, packing members 5A, 5B) for sealing the lower end side openings 12a, 12b to the outside, and the upper end of the outer casing 1 A connecting portion (projecting shaft portion 9, 9A) for the tip of the excavation rod is formed, and the hammer casing 2 has a knocking block 21 fixed to the lower end, and a drive hammer 22 that hits the knocking block 21 by free fall; A built-in lifting mechanism 6 that lifts the drive hammer 22 after dropping and releases the drive hammer 22 at a predetermined height is built in, and the penetrating shaft 3 whose tip is settled to the pile hole H in a state of being connected to the excavating rod is formed in the hole bottom ground (support layer) Gh) is configured to measure the supporting strength of the hole bottom ground from the number of times the drive hammer 22 is hit to penetrate to a predetermined depth.

  According to a second aspect of the present invention, in the penetration test machine M1, M2 for connecting the excavating rod according to the first aspect, the sealing means is provided between the periphery of the lower end side openings 12a, 12b and the intermediate portion of the penetration shaft 3. It is assumed to be composed of a fixed and expandable bellows cylinder 4.

  The invention of claim 3 is the drilling rod coupling penetration test machine M1, M2 according to claim 1 or 2, wherein the sealing means is a packing member 5A interposed on the inner periphery of the lower end side openings 12a, 12b. It is assumed to consist of 5B.

  According to a fourth aspect of the present invention, in the penetrating rod coupling penetration test machines M1 and M2 of the third aspect, a high internal pressure accumulating chamber 14 is provided at the lower end portion of the outer casing 1 and is isolated from the elevating space 10 of the hammer casing 2. The penetration shaft 3 is inserted through the packing members 5A and 5B in an airtight manner through the lower end side openings 12a and 12b provided through the ceiling portion 14a and the bottom plate portion 14b of the pressure accumulating chamber 14.

  According to a fifth aspect of the present invention, in the penetrating rod coupling penetration test machine M1, M2 according to any one of the first to fourth aspects, a shortening limit is provided between the inner upper portion of the outer casing 1 and the upper end portion of the hammer casing 2. A double tubular pipe stopper 7 for defining the upper and lower limit positions of the hammer casing 2 by the extension limit is interposed.

  According to a sixth aspect of the present invention, in the penetrating rod coupling penetration test machine M1, M2 according to any of the first to fifth aspects, the lifting mechanism 6 is a clamp provided at the tip of a piston rod 61a projecting downward from the hydraulic cylinder 61. The drive hammer 22 is gripped by the parts (clamp arms) 63, 63, and the drive hammer 22 is lifted and released at the upper limit position by the shortening operation of the piston rod 61a, and the hydraulic oil reaching the hydraulic cylinder 61 from the outside is released. In the supply / discharge path, a double-pipe expansion / contraction pipe 15 is interposed in the supply / discharge path between the inner upper portion of the outer casing 1 and the upper end of the hammer casing 2.

  According to a seventh aspect of the present invention, in the drilling rod coupling penetration testing machine M1, M2 according to any one of the first to sixth aspects, the encoder 8 for measuring the descending amount of the hammer casing 2 is provided in the upper part of the outer casing 1. The structure is

  According to an eighth aspect of the present invention, in the penetration test machine M1 for connecting the excavating rod according to any one of the first to seventh aspects, the excavating rod is the kelly bar K of the earth drill AD, and the connecting portion is fitted into the lower end opening on the kelly bar K side. Thus, the projecting shaft portion 9 is pinned.

  The ninth aspect of the present invention is the drilling rod coupling penetration test machine M2 according to any one of the first to seventh aspects, wherein the drilling rod is the screw rod Sc of the earth auger AA and the coupling portion is fitted on the screw rod Sc side. It is assumed that the projecting shaft portion 9A is inserted into the hole 9B and pinned.

  In the pile construction management method according to the invention of claim 10, after a drill hole H having a predetermined depth is formed in the ground G by rotating excavation of the excavation rod (Keriba K, screw rod Rs), The excavation rod coupling penetration test machines M1 and M2 according to any one of claims 1 to 9 are coupled to the distal end of the excavation rod in place of the excavation rod B1, the bottom expansion bucket B2, and the distal end rod member Rh). The drive hammer 22 required for the test shafts M1 and M2 to be inserted into the pile hole H and settled, and the penetration shaft 3 in contact with the hole bottom Hb to penetrate the hole bottom ground (support layer Gh) to a predetermined depth. The support strength (N value) of the hole bottom ground is determined from the number of times of hitting, and when the support strength is equal to or higher than a predetermined value, a pile (cast-in-place pile P1, ready-made pile P2) is built in the pile hole H It is a feature.

   Next, effects of the present invention will be described with reference numerals in the drawings. First, according to the penetration test machines M1 and M2 for connecting excavation rods according to the invention of claim 1, after forming a pile hole H of a predetermined depth in the ground G by rotary excavation of excavation rods (Keriba K, screw rod Rs), The penetration testing machines M1 and M2 are connected in place of the excavation tip member (shaft drilling bucket B1, widening bucket B2, tip rod member Rh) of the drilling rod, and the penetration testing machines M1 and M2 are piled in this connected state. When the penetration testing machines M1 and M2 are operated with the tip of the penetrating shaft 3 in contact with the hole bottom Hb, the penetrating shaft 3 is inserted into the hole H so as to bottom. ), The support strength of the hole bottom ground Gh can be measured very easily and reliably based on the number of hits of the drive hammer 22 required to penetrate to a predetermined depth. Moreover, in the penetration testing machines M1 and M2, since the drill rod used for drilling the pile hole H can be immediately inserted into the pile hole H after drilling, the support strength of the hole bottom ground can be measured. In addition to improving the workability of the entire pile construction including it, there is an advantage that the equipment cost can be reduced by that much without requiring special equipment for entering and exiting the penetration tester with respect to the pile hole H.

  Further, in the penetration testing machines M1 and M2, the lower end side openings 12a and 12b of the outer casing 1 through which the penetration shaft 3 is inserted are exposed to the outside by sealing means (bellows cylinder 4, packing members 5A and 5B). Since it can be sealed, it is ensured that mud sand, gravel, mud water in the pile hole H, stabilizing 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. Therefore, the reliability of the measured value can be secured, and the durability of the penetration test apparatus can be prevented from being lowered.

  According to the invention of claim 2, since the sealing means of the lower end side openings 12a, 12b of the outer casing 1 is made of the expandable / contractible bellows cylinder body 4, almost no resistance is given to the vertical movement of the penetrating shaft 3, It is possible to reliably prevent the entry of mud sand, sand gravel, mud water, stabilizing liquid and the like into the outer casing 1 from the lower end side openings 12a, 12b.

  According to the invention of claim 3, since the sealing means of the lower end side openings 12a and 12b of the outer casing 1 is composed of the packing members 5A and 5B interposed on the inner periphery of the lower end side openings 12a and 12b, the lower end side It is possible to reliably prevent the entry of mud sand, gravel, mud water, a stabilizing liquid and the like into the outer casing 1 from the openings 12a and 12b.

  According to the fourth aspect of the invention, since the high internal pressure accumulating chamber 14 is provided at the lower end portion of the outer casing 1, mud sand entering the outer casing 1 from the lower end side openings 12 a and 12 b through which the penetration shaft 3 is inserted. Intrusion of muddy water, stabilizing liquid, root-setting liquid, etc. is prevented by the high pressure in the pressure accumulating chamber 14.

  According to the invention of claim 5, the double tubular pipe stopper 7 is interposed between the inner upper portion of the outer casing 1 and the upper end portion of the hammer casing 2. Since the upper and lower limit positions of the hammer casing 2 are automatically determined, there is no need for a special drive mechanism for converting the hammer casing 2 into the measurement start position and the standby position. As well as an increase in production costs.

  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 15 and 15 are interposed, and the expansion and contraction pipes 15 and 15 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 smoothly supplied and discharged. 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 seventh aspect of the present invention, since the encoder 8 for measuring the lowering amount of the hammer casing 2 is provided in the upper part of the outer casing 1, the amount of penetration of the penetrating shaft 3 into the hole bottom Hb due to the knocking of the knocking block 21 is accurately determined. Can be caught.

  According to the invention of claim 8, in the construction of the cast-in-place pile by the kelly bar type earth drill method, the shaft drilling machine connected to the lower end of the earth drill machine AD used for drilling the pile hole is used. By connecting the penetration testing machine M1 in place of the bucket B1 and the expanded bottom bucket B2, the penetration testing machine M1 can be quickly inserted into the pile hole H and settled to easily measure the support strength of the hole bottom ground Gh. it can.

  According to the invention of claim 9, in the construction of the ready-made pile by the pre-boring method, the screw rod Sc of the earth auger AA used for drilling is used, and the penetration testing machine M2 is connected instead of the tip rod member Rh at the lower end. By doing so, the penetration testing machine M2 can be quickly inserted into the pile hole H and settled to easily measure the support strength of the hole bottom ground Gh.

  According to the pile construction management method according to the invention of claim 10, the excavation extracted from the pile hole H after forming the pile hole H at a predetermined depth in the ground G by rotary excavation of the excavation rod (Keriba K, screw rod Rs). The penetration testing machines M1 and M2 according to any one of claims 1 to 9 are connected to the tip of the excavation rod in place of the rod excavation destination member (shaft excavation bucket B1, widening bucket B2, tip rod member Rh). Then, the penetration testing machines M1 and M2 are inserted into the pile hole H and settled down, and the penetration shaft 3 abutting against the hole bottom Hb penetrates into the hole bottom ground (support layer Gh) to a predetermined depth. The support strength (N value) of the hole bottom ground is determined from the number of times the drive hammer 22 is struck, and it is determined that the piles (the cast-in-place pile P1, the ready-made pile P2) can be built when the support strength is a predetermined value or more. And pile construction in the pile hole H It can be completed rate well. 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.

1 illustrates a Kellyba type earth drill machine to which a drilling rod coupling penetration testing machine according to a first embodiment of the present invention is applied, (a) is a side view of the whole earth drilling machine before coupling the penetration testing machine; b) is a side view of the main part in a state in which the penetration tester is connected to the Keriba. The inside of the outer casing in 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 operation | movement of the pipe stopper of the penetration test machine is shown, (a) is a principal part fracture front view in an extension limit, (b) is a principal part fracture front view in a shortening limit. It is an expanded vertical sectional view of the lower part of the outer casing in the penetration tester. 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 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 partially sectional side view when the drive hammer is lifted, and (b) is a partially sectional side view when the drive hammer is released. The penetration test operation by the penetration tester is shown, (a) is the state where the tip of the penetration shaft of the penetration tester inserted into the pile hole is in contact with the bottom of the hole, (b) is the hammer casing by lowering the outer casing (C) is a longitudinal sectional front view of the state before the start of the test in which is the upper limit position, and (c) is a state where the penetration shaft is penetrated into the hole bottom ground. 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 testing machine in order of the process of (a)-(k). The earth auger three-point pile driving machine to which the penetration testing machine for excavation rod connection according to the second embodiment of the present invention is applied is illustrated, and (a) is a side view of the entire three-point pile driving machine before connecting the penetration testing machine. FIG. 4B is a side view of the main part in a state where the penetration tester is connected to the screw rod. It is a vertical front view which shows the inside of the outer casing in the penetration testing machine. The upper part of the penetration testing machine is shown, (a) is a plan view, (b) is a main part fracture side view. The connection state of the penetration tester and the screw rod is shown, (a) is a partially broken front view before connection, (b) is a front view after connection, and (c) is a YY line of (b). It is sectional drawing. It is a schematic longitudinal cross-sectional view which shows the pile foundation formation by the pre-boring method using the penetration test machine in order of the process of (a)-(h).

  DESCRIPTION OF EMBODIMENTS Embodiments of a drilling rod connection penetration tester and a pile construction management method according to the present invention will be specifically described below with reference to the drawings. 1 to 8 show a penetration testing machine M1 according to the first embodiment, and FIGS. 10 to 13 show a penetration testing machine M2 according to the second embodiment. In addition, the same code | symbol is attached | subjected to the component which is common in 1st and 2nd embodiment.

  The drilling rod connection penetration test machine M1 of the first embodiment is shown in FIG. 1 (a). The shaft drilling bucket B1 indicated by the solid line connected to the lower end of the kelly bar K of the earth drill machine AD and the bottom expanded indicated by the phantom line. Instead of the bucket B2, it is connected to the lower end of the kelly bar K as shown in FIG. The earth drill machine AD is composed of a traveling crane equipped with a boom Bo and a front frame F. The kelly drive device KD is held at the tip of the front frame F projecting obliquely forward, and the hoisting rope W is wound up by the boom Bo. The kerry bar K suspended through the kelly drive device KD is inserted into the kelly drive device KD so as to be movable up and down. A rotary table RT provided with a pair of hose reels Hr is attached below the kelly drive device KD. The rotary table RT is provided with a rotary coupling (not shown) for hydraulic and electric wiring.

  As shown in FIG. 2 (a), the penetration tester M1 has a cylindrical hammer casing 2 mounted in a vertically cylindrical outer casing 1 so as to be movable up and down. A protruding shaft portion 9 having a square shape in plan view protrudes from the top end of the taper plate 11, and a penetrating shaft 3 that hangs down from the center of the lower end of the hammer casing 2 penetrates the lower end of the outer casing 1 and protrudes downward and outward. The penetrating shaft 3 is made of steel and has a cylindrical shaft shape with an open tip. The sample shaft 3a is composed of a split barrel (not shown) whose tip side can be divided into two so that a geological sample can be collected. It has become. Further, a pin hole 90 for pinning and connecting to the lower end of the Kelly bar K is provided in the projecting shaft portion 9 horizontally.

  As shown in FIG. 2 (b), on the inner periphery of the outer casing 1, guide rails 16 composed of two parallel strips along the vertical direction are provided at a plurality of locations in the circumferential direction (four locations in the figure). The fitting keys 23 that are equally formed and project from the upper and lower portions of the outer periphery of the hammer casing 2 are slidably fitted to the guide rails 16 and are attached to the inner upper end of the outer casing 1. A double tubular pipe stopper 7 is interposed between the upper end of the hammer casing 2.

  The pipe stopper 7 is fitted in an outer cylinder 71 whose upper end is fixed to the center of the lower surface of the mounting plate 13 and an inner cylinder 72 whose lower end is fixed to the center of the upper end of the hammer casing 2 so as to be slidable vertically. As shown in FIG. 3A, the upper end outer periphery of the inner cylinder 72 is connected to the inward flange portion 71 a provided on the lower end inner periphery of the outer cylinder 71 in the extension limit where the inner cylinder 72 protrudes most from the outer cylinder 71. As a result, the inner cylinder 72 cannot be removed from the outer cylinder 71, so that the hammer casing 2 is in the lower limit position in the outer casing 1. On the other hand, as shown in FIG. 3B, the upper end of the inner cylinder 72 contacts the lower surface of the mounting plate 13 in the shortened limit in which the inner cylinder 72 is most retracted into the outer cylinder 71. It becomes the upper limit position within 1.

  Furthermore, between the mounting plate 13 of the outer casing 1 and the upper end of the hammer casing 2, a double-pipe type that constitutes a hydraulic oil supply / discharge path for a hydraulic cylinder 61 (see FIG. 5) described later in the hammer casing 2. These two expansion pipes 15 are interposed. Each telescopic pipe 15 is composed of an outer pipe 15a whose upper side is fixed to the outer casing 1 and an inner pipe 15b whose lower end is fixed to the hammer casing 2, but a bent pipe portion extending upward from the outer pipe 15a. 15c constitutes hydraulic joints J1 and J2 that penetrate the taper portion of the upper end taper plate 11 and protrude upward and connect hydraulic hoses h1 and h2 hanging from the rotary table RT of the earth drill machine AD through an adapter a. ing. Further, an encoder 8 for measuring the descending amount of the hammer casing 2 with respect to the outer casing 1 is attached to the lower surface side of the mounting plate 13, and a measurement cord 8 a extending from the encoder 8 is fixed to the upper end of the hammer casing 2. ing. The electrical wiring for the encoder 8 is inserted into one hydraulic hose h1 having a double structure.

  On the lower side of the outer casing 1, a pressure accumulating chamber 14 is provided that is isolated from the lifting / lowering space 10 of the hammer casing 2, and the pressure in the accumulating chamber 14 is increased by sealing with compressed air. The pressure accumulating chamber 14 is detachably bolted to the outer casing body 1a as an independent lower end member 1b. The penetration shaft 3 is inserted through the packing members 5A and 5B in an airtight manner into the lower end side openings 12a and 12b opened in the ceiling portion 14a and the bottom plate portion 14b of the pressure accumulating chamber 14, and the middle of the penetration shaft 3 A substantially cylindrical bellows cylinder 4 is fitted between the upper part and the outer peripheral part of the lower packing member 5B by fastening the upper and lower ends thereof liquid-tightly with fasteners 41 and 42 such as fastening bands. Yes.

  As shown in an enlarged view in FIG. 4, the upper packing member 5 </ b> A is formed of a thick circular annular plate at the center side, a plurality of seal rings 50 are fitted on the inner periphery, and the ceiling portion of the pressure accumulating chamber 14. 14 b is arranged concentrically with the lower end side opening 12 a and is bolted integrally with the lower mounting ring 51. On the other hand, in the lower packing member 5B, a flange portion 5b is integrally formed on the outer periphery of a cylindrical portion 5a in which a plurality of seal rings 50 are fitted on the inner periphery of the lower side, and the cylindrical portion 5a is located on the lower end side. The flange portion 5b is bolted to the bottom plate portion 15b via the cushion ring 52 in a state of being inserted into the opening portion 12b. Moreover, the bellows cylinder 4 is formed in a bellows shape with the same diameter as a whole by a flexible material such as rubber or semi-rigid synthetic resin, and the penetrating shaft accompanying the raising and lowering of the hammer casing 2 in the outer casing 1. The metal ring 40 for shape retention is fitted inside each ridge (valley) in order to prevent it from being crushed by water pressure.

  As shown in FIGS. 5A and 5B, the hammer casing 2 has a knocking block 21 fixed to the lower end thereof, a drive hammer 22 that strikes the knocking block 21 by free fall inside, and a drive hammer 22 after dropping. And a lifting mechanism 6 that lifts and lowers at a predetermined height.

  As shown in FIGS. 6A to 6C, the lifting mechanism 6 includes a pair of clamp arms 63, 63 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. An annular taper that is pivotally mounted in a vertical plane through pivot pins 62a each of which is a bolt, and that opens downward at the lower end outer peripheral portion of the hydraulic cylinder 61 and expands the inner peripheral lower portion downward. A short cylindrical grip releasing cylinder 64 serving as a surface 64a 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. The two hydraulic hoses h and h led out from the hydraulic cylinder 61 are connected to the upper expansion pipe 15 respectively. On the other hand, as shown in FIGS. 5 and 7, 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 the 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. 5 (a) and 7 (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. 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.

  In order to measure the supporting strength of the hole bottom ground with the penetration testing machine M1 having the above-described configuration, first, as shown in FIG. 8 (a), the Keriba K held in the earth drill machine AD (see FIG. 1 (a)). The projecting shaft 9 is inserted into a lower end opening (not shown) of the pin and pinned, thereby connecting the penetration testing machine M1 to the lower end of the Kelly bar K. In this connected penetration tester M1, since the outer casing 1 is supported by the Keriba K, the inner hammer casing 2 has its lower limit position in the outer casing 1, that is, the pipe stopper 7 becomes the extension limit due to its own weight. Accordingly, the protruding length of the penetrating shaft 3 from the lower end of the outer casing 1 is maximum, and the bellows cylinder 4 is also in the most extended state.

  Thus, the penetration testing machine M1 connected to the lower end of the kelly bar K is inserted into the previously formed pile hole H by lowering the kelly bar K in a non-rotating manner so as not to contact the hole wall. To bottom the hole bottom Hb. Therefore, in this bottoming, even if the descent of the hammer casing 2 stops by the tip of the penetrating shaft 3 coming into contact with the hole bottom Hb as shown in FIG. Since it can be moved up and down relatively, as shown in FIG. 8 (b), the outer casing 1 descends integrally with the kelly bar K with the retraction of the penetrating shaft 3 and the shortening of the bellows cylinder 4, and the hammer casing 2 Stops at the upper limit position in the outer casing 1, that is, the position where the pipe stopper 7 reaches the shortening limit. Then, the kelly bar K is fixed so that it cannot be moved up and down at the lowering stop position of the outer casing 1, and the penetration tester M1 is driven to perform a measurement test.

  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. 8 (c), the penetration shaft 3 penetrates into the ground G of the pile bottom Hb with the downward movement of the hammer casing 2 as shown in FIG. 8 (c). The number of impacts required for the shaft 3 to penetrate from the hole bottom Hb to a predetermined depth is measured, and based on the number of impacts, it is determined whether or not the support strength of the ground of the pile bottom Hb is greater than or equal to a predetermined value. In addition, as shown in FIG.8 (c), as the penetration of the penetration axis | shaft 3 with respect to the ground G deepens, the bellows cylinder 4 will expand | extend.

  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 penetration amount of the penetration shaft 3 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 electric wiring, and the amount of subsidence per one hit, that is, the penetration amount and the total penetration amount of the penetration shaft 3 with respect to the ground G are the number of strikes (N Value). 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 penetrating shaft 3 to penetrate 30 cm into the ground is expressed as an N value, this penetration testing machine M1 may grasp the support strength as an N value in accordance with the standard penetration test.

  Thus, if the measured support strength of the hole bottom ground is equal to or higher than a predetermined value, it is determined that the pile can be built, and the penetration tester M1 is extracted from the pile hole H by the upward movement of the Keriba K, and thereafter the earth drill Pile construction of cast-in-place piles according to the process procedure determined by the 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.

  In the construction of cast-in-place piles by the kelly bar type earth drill method to which the present invention is applied, as shown in FIG. 9, (a) a shaft excavation bucket Bp for excavation connected to the kelly bar K of the earth drill machine For excavating and discharging the soft layer Gs, (b) press-fitting a stunt pipe Ps into the excavation hole Hp, and (c) injecting a stable liquid Ls such as bentonite into the hole, Excavation and earth excavation are performed in the small-diameter shaft excavation bucket B1, and (d) a pile hole H having a depth reaching the hard support layer Gh in the deep underground is formed. Then, (e) the penetrating test machine M1 connected to the kelly bar K is inserted in the pile hole H after the shaft excavating bucket B1 is extracted, and (f) the penetrating test machine M1 is inserted into the pile hole H. If the support strength of the hole bottom ground is measured as described above and the support strength is equal to or greater than a predetermined value, (g) the pile hole H after being extracted from the penetration testing machine M1 Reinforcement rod Fc is built in, (h) Tremy tube Tp is inserted inside reinforcement rod Fc, (i) Slime S is discharged by introduction of air Air, (j) With the launch, the tremely pipe Tp is pulled out, and (k) the stunt pipe Ps is finally pulled out.

  In addition, although illustration is abbreviate | omitted, when forming the cast-in-place pile P1 after expanding the bottom part with the expanded-bottom bucket B2 [refer the virtual line of FIG. After the measurement of the supporting strength of the hole bottom ground by the penetration testing machine M1 in the step (f), the pile bottom portion is expanded by the bottom expansion bucket B2, or following the formation of the pile hole H in the step (d), the bottom expansion bucket B2 After the pile bottom portion is expanded by the measurement, the measurement by the penetration testing machine M1 may be performed.

  The penetration test machine M2 for excavation rod connection of the second embodiment is replaced with a tip rod member Rh that is connected to the lower end of the screw rod Rs of the earth auger AA used in the preboring method as shown in FIG. As shown in FIG. 10B, the screw rod Rs is connected to the lower end of the screw rod Rs. Thus, in the illustrated earth auger AA, the auger machine AM is mounted on the leader L held vertically of the three-point support pile driver so that the auger machine AM can be moved up and down, and the screw rod Rs is held at the upper end of the auger machine AM. ing. 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.

  In this penetration tester M2, as shown in FIG. 11, a connecting convex block 17A is fitted and fixed to the upper end of the outer casing 1 at the lower half of the small diameter, and a hexagonal projecting shaft in plan view at the center of the upper end. A portion 9A is integrally protruded, and a pipe stopper 7 and telescopic pipes 15, 15 similar to those in the first embodiment are interposed between the bottom surface of the convex block 17A and the upper end portion of the hammer casing 2. ing. Since the other parts have the same configuration as that of the penetration test machine M1 of the first embodiment described above, the same reference numerals as those of the first embodiment are used and description thereof is omitted.

  As shown in FIGS. 12 (a) and 12 (b), the protruding shaft portion 9A is formed with a locking groove 91 having a semicircular cross section along the lateral direction on the two side surface portions 9a and 9a facing each other in the radial direction. Yes. Further, on the upper surface of the convex block 17A, two of the plugs Jp of the hydraulic joint are planted at both radial positions sandwiching the protruding shaft portion 9A, and a phase difference of 90 degrees from both plugs Jp, Jp. The tip of the wire 8b with the connector through the wiring hole 17b provided in the convex block 17A is led out from the encoder 8 to the recess 17a provided at the position, and the recess 17a is removed along the periphery along the periphery. A ring O1 is fitted. The recess 17a is also open to the peripheral surface side, and a cover mounting concave surface portion 17c having a larger lateral width and vertical length than the recess 17a is formed on the open side. Further, as shown in FIG. 13A, the convex block 17A is provided with two oil passage holes 17d extending from the lower surface to the upper surface, and an oil pressure is provided at the upper end of each oil passage hole 17d. A joint plug Jp is screwed and fixed, and an expansion pipe 15 is connected to the lower end side.

  On the other hand, as shown in FIG. 13A, a connecting concave block 17B is fitted and fixed to the lower end of the screw rod Rs. This connecting concave block 17B has a hexagonal fitting hole 9B corresponding to the protruding shaft part 9A on the penetration tester M2 side in the center, and two pin insertion holes 93, which are provided in parallel to the peripheral surface part. 93 is formed with a locking groove 92 having a semicircular cross section on the opposing inner surface of the fitting hole 9B, and in a state where the protruding shaft portion 9A of the penetration testing machine M2 is inserted into the fitting hole 9B, The locking groove 92 and the locking groove 91 on the protruding shaft portion 9 </ b> A side are combined to form a hole with a circular cross section that is continuous with the pin insertion hole 93. Accordingly, as shown in FIGS. 13 (b) and 13 (c), the connecting convex block 17A of the penetration tester M2 and the connecting concave block 17B of the screw rod Rs are fitted into the pin insertion holes 93, 93. By inserting each locking pin 19, the penetration tester M2 is firmly connected to the lower end of the screw rod Rs. Each pin insertion hole 93 has a large diameter at one end side to accommodate the head 19 a of the locking pin 19.

  Further, as shown in FIG. 13 (a), the connecting concave block 17B of the screw rod Rs has a recess 17a, a wiring hole 17b, and a cover mounting similar to the connecting convex block 17A on the penetration tester M2 side. A concave surface portion 17c and an oil passage 17d are provided, and a tip of the electrical wiring 8c with a connector is led out from the recess 17a. In addition, each oil passage 17d communicates with a recess 17f whose bottom end is recessed from the side surface of the fitting hole 9B and opens downward, and a socket Js of a hydraulic joint is screwed to the bottom end, A hydraulic hose h passed through the hollow rod R is connected to the upper end side through an adapter a. Further, the screw rod Rs has a grout introduction path 17g penetrating along the axial direction in the center of the rear end of the fitting hole 9B of the connecting concave block 17B, and a hollow rod is provided at the upper end of the grout introduction path 17g. A grout supply pipe Pg disposed in R is connected.

  Therefore, when the connecting convex block 17A of the penetration tester M2 is fitted to the connecting concave block 17B, the hydraulic joint plug Jp and the socket Js of both the blocks 17A and 17B are automatically connected to each other to provide oil. It is set so that the recesses 17a and 17a of both the blocks 17A and 17B face each other, and the electric wirings 8b and 8c led out from the both recesses 17a and 17a are connected by a connector for the encoder 8 Can be formed. Further, after connecting the ends of the electric wirings 8b and 8c, as shown in FIG. 13 (b), the both concave portions 17a and 17a opened to the side are the concave surface portions 17c for attaching the covers of both the blocks 17A and 17B. , 17c is closed by a cover plate 18 having a shape and size that fits properly. As shown in FIGS. 12 (a) and 12 (b), the cover plate 18 includes a rubber layer 18a on the inner surface side, and covers two upper and lower bolts b that are penetrated from the outside via an O-ring O2. By screwing it into the screw hole n of the mounting concave surface portion 17c, both the concave portions 17a and 17a are hermetically sealed against the outside.

  In order to measure the supporting strength of the hole bottom ground with the penetration testing machine M2 having the above configuration, first, the penetration testing machine M2 is connected to the lower end of the screw rod Rs of the earth auger AA as described above. Since the penetration tester M2 in this connected state is supported by the screw rod Rs on the outer casing 1 side, the internal hammer casing 2 is moved outward by its own weight as in the penetration tester M1 of the first embodiment described above. It arrange | positions in the lower limit position in the casing 1, the protrusion length of the penetration shaft 3 from the lower end of the outer casing 1 is the largest, and the bellows cylinder 4 is also the most extended.

  Thus, the penetration test machine M2 connected to the lower end of the screw rod Rs moves the auger machine AM of the earth auger AA along the leader L so that it does not rotate in the previously formed pile hole H. It is inserted through the screw rod Rs, and is lowered so as not to contact the hole wall, and reaches the hole bottom Hb. In this bottoming, as in the penetration test machine M1 of the first embodiment, until the outer casing 1 stops with the retraction of the penetration shaft 3 whose tip is in contact with the hole bottom Hb and the shortening of the bellows cylinder 4. That is, the screw rod Rs is lowered until the pipe stopper 7 reaches the shortening limit, the auger machine AM is fixed at the lowering stop position of the outer casing 1, and the penetration test machine M2 is driven to perform a measurement test.

  The measurement test is exactly the same as in the case of the penetration test machine M1 of the first embodiment. As shown in FIGS. 5 (a) and 5 (b), the drive hammer 22 is driven by driving the lifting mechanism 6 in the hammer casing 2. The operation of hitting the knocking block 12 is repeated, and the number of hits (N value) required for the penetration shaft 3 to penetrate from the hole bottom Hb to the predetermined depth with the downward movement of the hammer casing 2 is measured, and based on the number of hits Then, it is determined whether or not the support strength of the ground of the pile bottom Hb is equal to or greater than a predetermined value. Then, if the measured support strength of the hole bottom ground is equal to or higher than a predetermined value, the pile can be built. Therefore, the penetration testing machine M2 is extracted from the pile hole H by the upward movement of the screw rod Rs, and thereafter Pile construction of ready-made piles is performed according to the process procedure determined by the boring 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.

  When the present invention is applied to the construction of a prefabricated pile by a pre-boring method using an earth auger, as shown in FIG. 14, (a) an auger machine AM that moves up and down along a leader (not shown) such as a three-point pile driver By lowering the screw rod Rs attached to the lower end while rotating, the ground G (soft layer Gs) is excavated by the excavating blade E of the tip rod member Rh connected to the lower end thereof, and (b) an assumed underground After the pile hole H having a depth reaching the deep support layer Gh is formed, (c) while the screw rod Rs is pulled up, a root-setting liquid Ls such as soil cement is injected, and (d) the hole periphery fixing liquid Lf is subsequently injected. To the top of the pile hole H, and the screw rod Rs is extracted. (E) The penetration testing machine M2 is connected to the screw rod Rs instead of the tip rod member Rh of the screw rod Rs, and the penetration testing machine M2 is inserted into the pile hole h by the downward movement of the auger machine AM. f) The penetration testing machine M2 is grounded to the hole bottom Hb, and the supporting strength of the hole bottom ground is measured as described above. If the supporting strength is a predetermined value or more, (g) connected to the auger machine AM. A ready-made pile P2 such as a PHC pile or an RC pile is connected via a rod Rj, and this ready-made pile P2 is inserted into the pile hole H. (h) The ready-made pile P1 is embedded in the pile hole H and piled. Complete construction.

  As is clear from the pile construction examples using the penetration test machines M1 and M2 of the first and second embodiments described above, according to the pile construction management method of the present invention, the excavation rod (Keriba K, screw rod Rs) After a pile hole of a predetermined depth is formed in the ground by rotary excavation, the penetration testing machine is connected in place of the excavation tip member (shaft excavation bucket B1, widening bucket B2, tip rod member Rh) of the excavation rod. In this state, the penetration tester is inserted into the pile hole and allowed to settle to operate, so that the support strength of the hole bottom ground can be measured very easily and reliably as an actual measurement value (N value). And if the support strength is greater than or equal to a predetermined value, piles can be built into the pile hole and pile construction can be completed efficiently, while if the support strength is less than the predetermined value, digging deeper, Alternatively, the pile hole may be backfilled and a new hole is drilled at a different position to determine the support strength in the same manner. 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. Moreover, in the penetration testing machine of the present invention, since the drilling rod used for drilling the pile hole can be immediately inserted into the pile hole after drilling and the supporting strength of the hole bottom ground can be measured, the pile construction including the penetration test The overall workability is improved, and there is an advantage that the equipment cost can be reduced as much as it does not require special equipment for entering and exiting the penetration tester with respect to the pile hole.

  Moreover, in this penetration testing machine, since the lower end side opening of the outer casing through which the penetration shaft is inserted can be sealed from the outside by the sealing means, mud sand, gravel, mud water in the hole, It is possible to reliably prevent the stable liquid and rooting liquid injected into the outer casing from entering the outer casing and hindering the lifting and lowering operation of the hammer casing, thereby ensuring the reliability of the measured value and reducing the durability of the penetration tester. Can be prevented. As this sealing means, various mechanisms can be adopted. However, if the bellows cylinder 4 that can be expanded and contracted is used as in the embodiment, the sealing can be performed with almost no resistance to the vertical movement of the penetrating shaft 3. The sealing can be easily performed by interposing packing members 5A and 5B as in the embodiment on the inner circumference of the lower end side openings 12a and 12b.

  Furthermore, if the accumulator chamber 14 having a high internal pressure is provided at the lower end portion of the outer casing 1 as in the embodiment, mud sand, muddy water, stabilizing liquid, rooting liquid, and the like from the lower end side openings 12a and 12b are caused by the high internal pressure. There is an advantage that intrusion can be prevented more effectively. In the configuration in which the pressure accumulating chamber 14 is provided, it is necessary to maintain the airtightness by interposing the packing members 5A and 5B in the lower end side openings 12a and 12b penetrating the pressure accumulating chamber 14, but as in the embodiment. Further, if the bellows cylinder 4 is further used, there is an advantage that the bellows cylinder 4 can surely prevent the sealing failure due to the biting of the solid particles into the packing.

  On the other hand, if a double tubular pipe stopper 7 is interposed between the inner upper portion of the outer casing 1 and the upper end portion of the hammer casing 2 as in the embodiment, the inner portion of the outer casing 1 is shortened and extended. Since the upper and lower limit positions of the hammer casing 2 are automatically determined, there is no need for a special drive mechanism for converting the hammer casing 2 into the measurement start position and the standby position. There is an advantage that the manufacturing cost is reduced while the performance is increased. Further, as in the embodiment, during the hydraulic oil supply / discharge path for the hydraulic cylinder 61 of the lifting mechanism 6, the double pipe type expansion / contraction is provided 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. If the pipes 15 and 15 are interposed, the expansion and contraction pipes 15 and 15 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. As compared with the case where the movable part of the supply / discharge path associated with the raising and lowering of the hammer casing 2 is constituted by a slack hydraulic hose, there is an advantage that the durability of the movable part is greatly improved.

  The penetration testing machine for excavation rod connection according to the present invention is suitable for connection to the kelly bar K of the earth drill machine AD as in the first embodiment and the screw rod Sc of the earth auger AA as in the second embodiment. Various other excavation rods used to form pile holes in the ground by rotary excavation are also subject to connection, and the structure of the connection part at the upper end of the outer casing is appropriately set according to the lower end structure of the target excavation rod. That's fine. 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 16 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 positions 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, A guide structure can be adopted. In addition, the detailed configuration of the penetration tester for pile holes of the present invention can be modified in various ways other than the embodiment.

DESCRIPTION OF SYMBOLS 1 Outer casing 10 Elevating space of hammer casing 12a, 12b Lower end opening part 14 Accumulation chamber 14a Ceiling part 14b Bottom plate part 15 Expansion pipe 2 Hammer casing 21 Knocking block 22 Drive hammer 3 Penetration shaft 4 Bellows cylinder (sealing means)
5A, 5B Packing member (sealing means)
6 Lifting mechanism 61 Hydraulic cylinder 61a Piston rod 63 Clamp arm (clamp part)
7 Pipe stopper 8 Encoder 9, 9A Projection shaft (connecting part)
9B Mating hole AA Earth auger AD Earth drill B1 Shaft-drilling bucket (drilling destination member)
B2 Expanded bucket (Drilling destination member)
G Ground Gh Support layer (hole bottom ground)
H Pile hole Hb Hole bottom K Keriba (Drilling rod)
M1, M2 Drilling rod connection penetration tester P1 Cast-in-place pile P2 Ready-made pile Rh Tip rod member (drilling tip member)
Rs screw rod (drilling rod)

Claims (10)

A drilling rod coupling penetration test machine that is used in place of the drilling tip member of the drilling rod for drilling the pile hole by rotary drilling, connected to the tip of the drilling rod,
A cylindrical hammer casing is loaded in a vertically cylindrical outer casing so as to be able to move up and down, and a penetrating shaft concentrically projecting downward from the lower end of the hammer casing projects downward and outward from the lower end side opening of the outer casing. And a sealing means for sealing the lower end side opening to the outside, and a connecting portion for the tip of the excavation rod is formed at the upper end of the outer casing,
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,
It is configured to measure the support strength of the bottom of the ground from the number of times the drive hammer is hit by the penetrating shaft with the tip bottomed in the pile hole in a state where it is connected to the excavation rod, to penetrate the bottom of the hole to a predetermined depth. Penetration testing machine for connecting excavation rods.   The drilling rod coupling penetration test machine according to claim 1, wherein the sealing means comprises an extendable bellows cylinder fastened between a peripheral portion of the lower end side opening and an intermediate portion of the penetration shaft. .   The drilling rod coupling penetration tester according to claim 1, wherein the sealing means is formed of a packing member interposed on an inner periphery of the lower end side opening.   A high internal pressure accumulating 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 opening portion penetrating the ceiling portion and the bottom plate portion of the accumulator chamber serves as the packing member. The penetration testing machine for excavation rod connection according to claim 3, wherein the penetration test machine is inserted in an airtight manner.   The double tubular pipe stopper which defines the upper and lower limit positions of the hammer casing by a shortening limit and an extension limit is interposed between the inner upper part of the outer casing and the upper end of the hammer casing. Penetration testing machine for connecting excavation rods as described in 1. 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 machine for connecting a drilling rod according to any one of the above.   The penetration test machine for connecting a drilling rod 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.   8. The penetration test for connecting a drilling rod according to any one of claims 1 to 7, wherein the drilling rod is a ground drill kelly bar, and the connecting part is a protruding shaft part that is fitted into a lower end opening on the kelly bar side and pinned. Machine.   The excavation rod connection according to any one of claims 1 to 7, wherein the excavation rod is a screw rod of an earth auger, and the connection portion includes a projecting shaft portion that is fitted into a fitting hole on the screw rod side and pinned. Penetration testing machine.   The drilling rod connecting penetration testing machine according to any one of claims 1 to 9, wherein a pile hole having a predetermined depth is formed in the ground by rotating excavation of the excavation rod, and the excavation rod connecting penetration testing machine according to any one of claims 1 to 9 is used instead of the excavation tip member. The number of hits of the drive hammer required for the penetration shaft that is in contact with the bottom of the hole to penetrate into the bottom of the hole to a predetermined depth is inserted into the pile hole and grounded. The pile construction management method characterized by determining the support strength of a hole bottom ground from the bottom, and building a pile in this pile hole when this support strength is more than predetermined value.

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