JP3834575B2 - Steel pipe pile driving method - Google Patents

Description

The present invention relates to a method for driving a steel pipe pile to be used to reinforce a ground portion that is the foundation of a civil engineering building.

  As a conventional steel pipe pile, what provided the screw blade | wing at the front-end | tip part and made rotation press fit easy is known. When such a screw steel pipe pile is used, the manufacturing cost of the pile becomes high, the screw part becomes an obstacle during transportation and storage, and the stratum around the tip of the steel pipe is roughened during press fitting, so it is difficult to maintain uprightness. There was a disadvantage that the surrounding ground of the island was easy to sink.

Therefore, initial settlement is unlikely to occur, the bearing capacity in the soil is stable, penetration into hard ground is easy, transportation, storage and on-site processing are easy, and the ground around the steel pipe tip is upright without being roughened. A steel-pipe-type steel pipe pile with brazing has been developed that not only retains its properties but also provides compaction effects and accuracy. This steel pipe pile has a bottom cover fixed inside the tip of the main body formed in a hollow cylindrical shape, and after rotating and press-fitting into the soil the tip side of the steel pipe pile fixed with a blade protruding outside to the bottom cover A bottom expansion screw cylinder is fitted and welded to the distal end side of the main body (for example, see Patent Document 1).
Japanese Patent No. 3135220 (see page 2, Fig. 1)

  In the conventional steel pipe pile, since the soil on the pile peripheral surface above the expanded screw cylinder is loosened by the screw cylinder, it is difficult to ensure the friction support force of the upper pile peripheral surface over a certain level.

Then, an object of this invention is to provide the driving method of the steel pipe pile which improved the front end support force and peripheral surface friction support force of the steel pipe pile as a whole, and improved the uprightness of the pile .

In order to achieve the above-described object, the present invention provides a hollow tubular steel pipe pile driving method for connecting an upper pile to a lower pile, wherein the lower pile is (a) the tip of the hollow tubular lower pile body. A bottom cover fixed to the inside, (b) a blade protruding to the outside fixed to the bottom cover, (c) a cylindrical portion inserted and fixed to the distal end side of the lower pile body, and (d) the cylindrical portion (E) a part of this collar part cut in a radial direction at a substantially intermediate height position on the outer periphery and in a horizontal direction, and the cut parts in mutually opposite directions 30 ° to It is composed of inclined blades formed by bending so as to be inclined at an angle of 45 °, and has a hollow cylindrical shape with open ends, and an upper pile fitted into the lower pile is (f) the tip side of the upper pile body A flange portion that extends in a horizontal direction and is fixed to the peripheral surface; (g) a V-shaped inclined protrusion provided on the lower surface of the flange portion ; Pressed into the soil while rotating the lower pile, the tip portion of the Shitakui a predetermined depth stops rotation when it reaches further pressed down piles in the soil subsequently pressed only, then the upper pile It fits into the lower pile and presses it into the soil while rotating only the upper pile. When the tip of the upper pile reaches the specified depth, it stops rotating, and then press-fitted to unravel the lower pile. The soil is consolidated with the flange of the upper pile.

According to the present invention, a hollow tubular steel pipe pile driving method for connecting an upper pile to a lower pile, wherein the lower pile is fixed to the inside of the tip of the hollow tubular lower pile body (a). A lid, (b) a blade protruding to the outside fixed to the bottom lid, (c) a cylindrical portion inserted and fixed to the distal end side of the lower pile body, and (d) a height approximately in the middle of the outer periphery of the cylindrical portion. (E) A part of this collar part is cut in the radial direction, and the cut parts are inclined in the opposite directions by an angle of 30 ° to 45 °. It is composed of inclined blades formed by bending so as to form a hollow cylindrical shape with open ends, and an upper pile fitted into the lower pile is horizontally oriented on the front peripheral surface of the upper pile body (f) (G) It is composed of a V-shaped inclined protrusion provided on the lower surface of the flange portion, and the lower pile is not rotated. Above was pressed into reluctant soil, the tip portion of the Shitakui a predetermined depth stops rotation when it reaches, then further pressed down piles in the ground press-fitting only, the on piles fitted underneath Pile When only the pile is rotated, it is pressed into the soil, and when the tip of the upper pile reaches the specified depth, the rotation is stopped, and then the soil that has been unraveled at the buttocks of the lower pile is pressed into the flange of the upper pile. As a result, the lower pile can be pressed firmly to the hard ground and the tip support force can be increased. Supporting ability is also improved.

  In the following, preferred embodiments of the present invention will be described with reference to the drawings.

  In the embodiment shown in FIG. 1, for example, a steel pipe pile formed by connecting a hollow cylindrical lower pile 1 and an upper pile 2 having a certain strength and made of a material such as structural carbon steel is driven into the soil. . The lower pile 1 has a bottom lid 11 fixed inside the tip of the lower pile body 10, and a blade 12 fixed to the bottom lid 11 protrudes to the outside. A cylindrical portion 21 inserted and fixed to the tip side of the lower pile 1, a flange portion 22 formed in a substantially disc shape in the horizontal direction at a substantially intermediate height position on the outer periphery of the cylindrical portion 21, A screw cylinder 20 is formed from an inclined blade 23 formed by cutting a part of the portion 22 in the radial direction and bending the cut portions in an opposite direction to be inclined at an angle of 30 ° to 45 °. is there. The diameter W of the flange portion 22 of the lower pile 1 is formed 2.5 to 3 times the outer diameter D of the cylindrical portion 21, and the length L from the distal end portion of the main body 10 to the flange portion 22 is The opening angle α (see FIG. 2) of the inclined blades 23 which are formed to be approximately twice the outer diameter dimension d and are inclined in opposite directions to each other is formed around 60 °.

  A hollow cylindrical upper pile 2 having openings at both ends is provided with a flange portion 4 extending in the horizontal direction and fixed to the tip side of the upper pile body 3, and a V-shaped inclined protrusion 5 is provided on the lower surface of the flange portion 4. is there. The outer diameter WB of the flange portion 4 of the upper pile 2 and the outer diameter (diameter W) of the flange portion 22 of the lower pile 1 are the same or larger than the outer diameter of the flange portion 4 (WB ≧ W). A protrusion (stopper) 6 is provided on the upper portion of the upper pile 2 in the hollow cylinder, and the upper end of the lower pile 1 is engaged with the protrusion (stopper) 6 so that the upper pile 2 and the lower pile 1 are connected. It is. Or after driving both piles, you may weld this part. Further, a rotation transmission protrusion 7 is provided on the upper end side inner peripheral surface of the lower pile 1, and a rotation transmission protrusion 8 is also provided on the upper end side outer periphery of the upper pile 2. In addition, the soil layer shown by the code | symbol A shows the hard ground where the front-end | tip of the lower pile 1 is supported firmly, and the soil layer shown by B is the screw cylinder 20 of the lower pile 1, and the flange part 4 of the upper pile 2. A soil layer indicated by C indicates a soil layer above the flange portion 4.

  FIG. 2 shows the details of the lower pile 1 and shows the relationship between the flange 22 of the screw cylinder 20 and the inclined blades 23 in detail. The size of the outer diameter D of the screw cylinder 20 is preferably in the range of about 1.3 to 2 times the outer diameter d of the lower pile body 10. Further, as a material for forming the screw cylinder 20, high-tensile steel or the like is suitable for use. Furthermore, the mounting position of the screw cylinder 20 is provided where the length L from the distal end portion of the lower pile body 10 to the flange portion 22 is a distance approximately twice the outer diameter dimension d of the lower pile body 10. It is.

  FIG. 3 is a plan view of the screw cylinder 20, and the cylindrical portion 21 has a straight cylinder shape (outer diameter D) and is formed to have a length S that is substantially the same as or slightly shorter than the outer diameter D. (See FIG. 4). Note that the length S only needs to be sufficient to ensure the straightness and strength of the screw cylinder 20, and it is not necessary to be particularly equal. The flange portion 22 is formed of a substantially disk shape having a diameter W (about 2.5 to 3 times the outer diameter D), and is attached (welded) to substantially the middle of the cylindrical portion 21. is there. The inclined blades 23 are formed in a part of the ridge part 22 (one place in this embodiment), and cut the ridge part 22 in the radial direction (this also forms a gap through which soil escapes), The cut portions are bent so as to be inclined in the opposite directions by an angle θ (approximately 45 °, preferably in the range of 30 ° to 45 °). Further, the range of the opening angle α of the inclined blades 23 is around 60 ° as shown in FIG. 4, and a substantially isosceles trapezoidal reinforcing plate is provided on one side of the inclined blades 23 (toward the tip side). 24 is welded between the flange portion 22. The screw cylinder 20 as shown in FIGS. 3 and 4 may be fixed to the lower pile body 10 in advance, but separately from the lower pile body 10 so as not to disturb the storage and transportation. The screw cylinder 20 may be stored, transported, and welded to the lower pile body 10 at a predetermined position at the pile driving site.

FIG. 5 is an enlarged cross-sectional view showing the relationship between the bottom lid 11 and the blade 12 at the tip portion of the lower pile body 10, where the bottom lid 11 has a half depth (d _1/2) of the inner diameter d ₁ of the lower pile body 10. ) the is provided with, also the height of the blade 12 is in the same inner diameter d _1.

  6 and 7 are a side view and a plan view of the upper pile 2, and the total length of the upper pile 2 is preferably 10% to 50% of the total length of the lower pile 1. The outer diameter WB of the flange portion 4 is formed to be the same as or slightly larger than the outer diameter W of the flange portion 22. In addition, although a pair of left and right inclined protrusions 5 are provided, four or more may be provided at each radial position obtained by dividing the flange portion 4 into four equal parts in the circumferential direction. The inner diameter d of the upper pile body 3 is the same as the outer diameter d of the lower pile body 10, but the inner diameter of the upper pile body 3 may be slightly larger than the outer diameter of the lower pile body 10. Then, as shown in FIG. 1, the upper pile 2 is fitted and connected so as to cover the lower pile 1, and the lower pile 1 is inserted into the upper pile 2. It is desirable that the portion inserted into the upper pile 2 of the lower pile 1 occupies 2/3 or more of the upper pile 2.

  FIG. 8 is a diagram schematically showing a rotary press-fitting device, which is of a rubber crawler traveling type, and has hydraulic auger mechanisms 101 on both sides of a leader 100 (raising and lowering) firmly fixed upright on the ground by an outrigger (not shown). And a press-fitting machine 103 with a rotating hydraulic motor 102. Reference numeral 104 denotes an auger, and reference numeral 105 denotes a chuck. In this apparatus, the hydraulic auger 101 is operated, the auger 104 is rotated and screwed into the soil, and pushed to a predetermined depth to firmly fix the entire apparatus including the reader 100. Subsequently, the press-fitting machine 103 with the rotation hydraulic motor 102 is operated, and the lower pile 1 is press-fitted into the soil while taking a reaction force by the auger 104. In the case where the lower pile 1 is press-fitted, only the press-fitting operation is required when the front side of the lower pile 1 advances through the soft soil, that is, the soft soil layer. When the tip of the lower pile 1 passes through the soft stratum and advances through the intermediate soil, the rotary hydraulic motor 102 is operated from the point where the press-fitting operation cannot be performed only by the press-fitting operation. Press-fit while rotating. If the tip of the lower pile 1 passes through the intermediate stratum and reaches the hard soil, the lower pile 1 is finally press-fitted only by the press-fitting operation again. Finally, the hydraulic auger mechanism 101 is reversely rotated to pull up the auger 104 from the ground. The auger 104 is screwed and lifted together with the rotation of the hydraulic auger mechanism 101 and the hydraulic auger mechanism 101 itself is provided in the reader 100. The auger 104 is forcibly moved up and down by a chain (not shown) so that the auger 104 can be screwed and lifted reliably.

  FIG. 9 shows a state in which the lower pile 1 is driven into a hard formation, that is, a formation that strongly supports the tip. When the lower pile 1 is press-fitted in this state, a load measuring device such as a load sensor attached to the presser 103 side. Is used to automatically measure the supporting capacity of the soil. A certain portion above the screw cylinder 20 shown in FIG. 9 shows an upper discharge soil layer X, and further, there is a loosening layer Y thereon. When the frictional force around the lower pile 1 due to the moistening layer Y is not sufficient, sand, crushed stone, solidifying material, or a mixture thereof can be additionally added to form the filler layer Y ′. Thereby, the frictional support force of the lower pile 1 can be increased. The code | symbol 9 in FIG. 10 shows the lid | cover provided so that it might not enter into the hollow inside of the lower pile 1 when filling with a filler.

  FIG. 11 shows a state where the lid 9 is removed from the state of FIG. 10 and the upper pile 2 is fitted to the upper end side of the lower pile 1 (the lower pile 1 is inserted into the hollow interior of the upper pile 2).

  As shown in FIG. 11, the upper pile 2 is fitted into the lower pile 1, and the upper pile 2 is mounted on the chuck 105 of the press-fitting machine 103 and press-fitted into the soil while rotating. At this time, the flange portion 4 descends while consolidating the kneading layer Y or the filler layer Y ′. The tip of the lower pile 1 is supported by a hard stratum, and there is almost no further press-fitting. If the lower pile 1 is inserted to a certain point inside the upper pile 2 (until it hits the stopper 6) and the upper pile 2 has obtained a predetermined tip support force, the rotation is stopped and pressure is applied from above the upper pile 2. In addition, press fit.

  FIG. 13 shows a state in which the upper pile 2 and the lower pile 1 are welded after the operation in FIG. The weld location is the upper end of the stopper 6 and the lower pile 1. The upper pile 2 can be moved up and down with respect to the lower pile 1 without welding this portion, so that it is possible to cope with an earthquake. Thus, after rotating the upper pile 2 in the soil and press-fitting it, the rotation is stopped and a predetermined pressure is applied to the upper end of the upper pile 2. At this time, the circumferential frictional support force of the upper pile 2 is measured by a load measuring device such as a load sensor attached to the presser 103 side. Then, after welding the upper and lower piles, press again to measure the combined pile bearing capacity of the upper and lower piles.

  In the method of measuring the bearing capacity of ready-made piles, calculate the bearing capacity by using a calculation formula based on pre-collected geological survey data, or after applying piles and applying a load to the pile head after a specified curing period. It is common to do it. However, the geological survey points necessary for the calculation formula are usually limited to a few points in the planned construction site and do not cover each pile driving point. For this reason, in the case where the supporting stratum is inclined or complicated, there is a possibility that the uniform distribution of the supporting force to the entire foundation becomes uncertain. In addition, the load bearing capacity measurement is generally performed only on typical piles in terms of cost and construction period, and it is difficult to say that they have been scrutinized. There is no support capacity separation. Therefore, the supporting force measuring method measures the tip supporting force at the time of final pressurization when the lower pile 1 is placed, and then measures the pile peripheral surface friction supporting force at the time of final pressurization when the upper pile 2 is placed. . Next, after fixing the upper and lower piles, press again to measure the combined pile bearing capacity. Based on the above measurements, three types of bearing capacity values can be clearly identified and used appropriately for long-term ground changes and changes (eg, fault changes in the formation, fluctuations in water level, liquefaction due to earthquakes, etc.). This measurement method (loading the construction machine weight and the load from the underground reaction force acquisition device and recording the measured value) can be carried out in a short time at the same time as placing, so for all the piles placed The impact on cost and construction period is negligible.

  As described above, as a method of press-fitting the lower pile 1 into the soil, the screw cylinder 20 having the flange portion 22 whose outer diameter dimension W is significantly larger than the outer diameter d of the lower pile body 10 is rotated into the ground. Since the press-fitting is performed, a compacting action (a state in which the soil is hard and compressed at the time of the press-fitting) is generated over the lower region larger than the main body 10 indicated by reference symbol A in FIG. Since the region of the soil that is not so wide spreads and expands below the heel part 22, the pile tip support force is further increased. Further, unlike the conventional screw steel pipe pile, the flange portion 22 is formed in the horizontal direction, so that not only the effective area can be secured, but also the torsional displacement hardly occurs. Moreover, in this embodiment, the inclined blades 23 are provided together with the blades 12, and the soil can be efficiently discharged to the upper part from between the inclined blades 23 during the rotary press-fitting, so that the discharged soil is filled around the main body 10. The vertical stability of the lower pile 1 (preventing the hollowing of the surrounding surface of the pile) is brought about. Further, the inclined blade 23 allows the tip portion of the lower pile body 10 to excavate the prepared hole with high accuracy by the center drill effect, and the tip portion protrudes from the flange portion 22 by an L length (see FIG. 2). As a result, straight-line performance also increases dramatically.

  In addition, after driving the lower pile 1 into the soil in this way, the upper pile 2 is connected to (inserted into) the lower pile 1 and driven into the soil as described above. Since this compacted soil is pushed from the circumference of the pile toward the outer periphery by being compacted so that the soil discharged around the pile between the lower surface of the flange 4 is sandwiched, the distribution information of soil texture around the pile If it grasps | ascertains, consolidation of a pile peripheral surface is accelerated | stimulated effectively and a pile peripheral surface frictional support force can be acquired reliably. Further, the excavated crushed soil discharged upward by the ridge portion 22 is filled with crushed stone, sand and mixed aggregates into a space formed by rotating and consolidating the flange portion 4 and further compacted, thereby achieving high friction. Support force may be obtained, and strengthening of the entire ground is also achieved by the consolidation effect of the formation.

Sectional drawing which shows the steel pipe pile used by this invention. Sectional drawing of a lower pile. The top view of the screw cylinder which adheres to a lower pile. The front view of a screw cylinder. Detailed sectional drawing of a lower pile tip. The side view of an upper pile. The top view of an upper pile. The principal part explanatory drawing which shows the rotary press-fitting apparatus of a steel pipe pile. Explanatory drawing of the driving state of the lower pile by a rotary press-fitting device. Explanatory drawing at the end of driving the lower pile. The figure of the state which inserted the upper pile in the lower pile. Explanatory drawing of the state which drives in an upper pile. Explanatory drawing which adheres an upper and lower pile at the time of completion | finish of upper pile driving.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lower pile 2 Upper pile 3 Upper pile main body 4 Flange part 5 Inclination protrusion 10 Lower pile main body 11 Bottom cover 12 Blade 21 Cylindrical part 22 Gutter part 23 Inclined blade

Claims (3)

A hollow tubular steel pipe pile driving method that connects the upper pile to the lower pile,
The lower pile is composed of the following (a) to (e),
(A) a bottom lid fixed to the inside of the tip of the hollow cylindrical lower pile body,
(B) an outwardly protruding blade fixed to the bottom lid;
(C) a cylindrical portion inserted into and fixed to the tip side of the lower pile body,
(D) a collar portion formed in a substantially disc shape in the horizontal direction at a substantially middle height position on the outer periphery of the cylindrical portion;
(E) An inclined blade formed by cutting a part of the collar part in the radial direction and bending the cut parts so as to be inclined in the opposite directions by an angle of 30 ° to 45 °,
It is a hollow cylindrical shape with open ends, and the upper pile fitted into the lower pile is composed of the following (f) to (g),
(F) A flange portion that extends horizontally and is fixed to the peripheral surface on the front end side of the upper pile body,
(G) A V-shaped inclined protrusion provided on the lower surface of the flange,
When this lower pile is rotated, it is pressed into the soil, and when the tip of the lower pile reaches a predetermined depth, the rotation operation is stopped, and then the lower pile is further pressed into the soil only by pressing.
Then pressed only on piles in the ground while rotating by fitting the on pile under pile tip portion of Uekui a predetermined depth stops rotation when it reaches, under piles by then pressed A steel pipe pile driving method characterized in that the soil loosened in the buttock is consolidated by the flange of the upper pile. The steel pipe pile driving method according to claim 1 , wherein the pile peripheral surface above the flange portion of the upper pile is filled with a filler and consolidated. Measure the tip support force during the final pressurization of the lower pile, measure the tip support force of the upper pile also during the final pressurization of the upper pile, and pressurize again in the connected state of the upper and lower piles to combine the upper and lower piles 3. A pile driving method for steel pipe piles according to claim 1 or 2 , wherein pile supporting force is measured.