JPS63167808A - Naturally screwing pile and penetrating work of pile - Google Patents

Abstract

PURPOSE:To prevent the occurrence of vibration by a method in which a spiral projected line is formed on the periphery of a round pile to be driven so that a rotation movement around the pile shaft is naturally generated as the pile penetrates into the ground, and after the penetration, a fixing part is attached to the head of the pile to prevent the natural rotation. CONSTITUTION:A pile 3 with a cap 4 is additionally connected through a connector 2 to the head of spiral form 1, having a spirally projected line 1' of great advancing angle. A wire rope 6 whose one end is fixed to the ground's surface is engaged with a pulley 5 and a pile 1 is penetrated by a penetrating winch 7. In this case, a pile-supporting cylinder 10 with female screw is held by a soil pressing board 9 on the ground's surface 8. The pile 1 penetrates slowly and naturally with rotation into the ground through one or multi-projected lines 1' without disturbing soil. After the driving, the head of the pile is fixed to prevent its rotation. The penetrating work can thus be performed without noise and vibration and great bearing force can be provided for the pile.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a natural rotation press-in shaft and a pile press-in method that allow vibration-free and noise-free driving in construction foundation work.

[Conventional technology]

In recent years, in civil engineering and architectural foundation work, screwed piles with spiral strips are sometimes used as a construction method when vibration-free and noise-free construction is required.

When screwed piles are ideally applied, a large bearing capacity can be expected due to the collar action of the threads.

However, compared to screwing steel screws into wood,
When screwing concrete piles into the ground, the mechanical properties of the soil vary greatly from site to site, so the screwing conditions vary greatly depending on the location.

In other words, with screwed concrete piles, there is a range of variation in resistance and support that is comparable to when screwing a screw into rotten wood or into a joint. Therefore, if the soil is soft, the pile may not necessarily penetrate through the screwing operation, but may excavate and eject the soil like an auger bit.

On the other hand, when dealing with boulders in the soil, the strength of the boulders often exceeds the partial strength of the pile, which often results in difficulties such as impossibility of screwing in or damage to the pile.

Therefore, there are not necessarily many cases where the features of screwed piles can be fully demonstrated.

[Problem that the invention seeks to solve]

The helical pile screwing method applies continuous rotational force, resulting in low noise and low vibration, but on the other hand, it is only capable of amplifying force through impact motion, resulting in low power efficiency and requiring large mechanical equipment.

The present invention attempts to solve this problem by employing a rotating spiral pile based on the opposite idea to conventional piles with spiral grooves.

[Means for solving problems]

The present invention will be described in detail as follows with reference to the accompanying drawings.

A spiral convexity along the outer periphery of a driving round pile with a large advance angle that causes rotational movement around the pile axis as it penetrates into the ground due to the pressing force applied in the axial direction of the pile. It is characterized by the provision of Article I''.

In addition, along the outer circumference of the round pile for driving, a spiral shape with a large advance angle that causes rotational movement around the pile axis as the penetration progresses into the ground due to the pressing force applied in the axial direction of the pile. After penetrating the rotatable helical pile 1 with a 1° protrusion into the ground to the required depth, fixing member 1 is attached to the top of the pile.
This feature is characterized in that the subsequent natural rotation of the pile 1 is restrained by attaching a ``.'' to the pile 1.

Also, the axial direction of the pile along the outer circumference of the round pile for driving? When press-fitting a self-rotating helical pile l with a 1° spiral protrusion having a large advance angle that causes rotational movement around the pile axis as it penetrates into the ground due to the applied pressing force, This method is characterized in that the support force of the pile is calculated by measuring the press-in force, and press-fitting is stopped when the support force reaches a predetermined value.

In addition, along the outer circumference of the round pile for driving, a spiral shape with a large advance angle that causes rotational movement around the pile axis as the penetration progresses into the ground due to the pressing force applied in the axial direction of the pile. When press-fitting the self-rotating helical pile 1 with a 1° protrusion, an earth-holding plate 9 is provided, and the helical pile 1 is placed on this earth-holding plate 9.
A pile support tube 10 having a female thread matching the male screw of the pile support tube 10 is erected, and the screwed helical pile 1 is press-fitted into this support tube 10.

[Effect]

In contrast to conventional piles with spiral striations, which are screwed in using a principle similar to the advancement of a screw by applying a rotational force, the pile of the present invention is penetrated by being compressed in the axial direction.

One or more protrusions (spiral ribs) are provided on the surface with a large advance angle that allows the soil to penetrate while rotating naturally and slowly without disturbing the removed soil.

Therefore, the mechanical conditions during press-in of the pile with spiral ridges of the present invention are almost the same as those of conventional round piles, but the total surface area and section modulus are slightly increased due to the spiral ridges. The difference is that due to the rotation that accompanies press-fitting, the relative velocity of the pile surface to the soil becomes diagonal, and becomes a value somewhat greater than the penetration velocity of the pile.

In order for the pile to penetrate and rotate due to axial reduction, the spiral protrusions provided on its surface must have a pitch or lead so large that it departs from the concept of a normal screw.

The limits for such spiral protrusions to rotate on their own axis are explained as follows.

FIG. 1 shows, as an example, a round pile with a single spiral protrusion having a trapezoidal cross section.

FIG. 2 shows the relationship between the axial force Q on the surface of the spiral protrusion and the force along the slope.

The force that tries to move in the direction of the slope due to the force Q applied in the axial direction is Q sin α, and the force that presses on the slope is Q cos
Since α is, let μ be the friction coefficient between the pile surface and the soil.
The frictional force opposing the screwing of the pile is μQ cosα.

Therefore, when Qsinα=μQcosα holds true, it is the limit whether the pile descends obliquely, that is, rotates, or not along the spiral protrusion.

From the above equation, μ = tanα, but since tanα−p/πd as shown in Figure 3, μ=p/μd, and the rotation condition of the pile during penetration can be expressed as p〉μπd. can.

These relationships are shown in Table 1 below for various μ.

Table 1 μ p/d α 0.1 0.31 5.7°0.2
0.63 11 0.3 0.94 17 0.4 1.26 22 0.5 1.57 27 0.6 1.88 31 0.7 2.20 35 0.8 2.51 39 0.9 2 .83 42 1, [l 3.14 45 (1,19)
3.74 50 (1,73) 5
．． 43 60 (3,73) 11.72
75 However, μ is the friction coefficient p/d between the pile surface and the soil, the ratio of the pitch length of the helix to the pile diameter, and α is the advance angle of the helix.

Table 1 shows the values when the spiral protrusion is square (when θ - 0° as shown in 13 in Figure 1), and when the spiral protrusion is trapezoidal or triangular, the slope Due to the angle θ, all the p/d values in Table 1 increase to the value divided by their COS θ.

For θ-15°, 1.04 times; for θ-30°, 1.
It becomes 15 times.

Now, the feature of the pile of the present invention is that the spiral protrusion is not used for the purpose of screwing in or excavating, but it is made to rotate and penetrate after a small and low force that is almost the same as a normal round pile. In addition, by restraining the rotational movement on the horizontal plane of the ground surface, the outer diameter of the brim and the depth of the pile in the ground can be simultaneously seen across the entire surface of the cylindrical surface of the ground due to the brim action of the spiral protrusions. This is an attempt to effectively obtain a large support reaction force in the axial direction by utilizing the shear force of the soil that acts on the ground.

The rotational force associated with penetration is maximized to minimize soil disturbance, and after driving, the helical lead angle is Larger screws are suitable, far from the concept of mechanical screws and screw nails.

As an extreme example, it is sufficient for the spiral strip to make one revolution over the entire length of the pile. On the other hand, with this helical pile, the change in bearing capacity is converted into a greatly expanded rotational force due to the slope principle or wedge principle, so if the rotation is not restrained in some way after driving, it is just an odd shape. It cannot be more than equivalent to a cross-section pile.

Therefore, the top of the pile should have a shape suitable for preventing rotation.

In addition, by measuring the press force at the time of pouring with a load cell and converting that value into the bearing capacity of the pile, press-fit until a press-in force equivalent to the specified bearing capacity is obtained. By stopping this, a predetermined supporting force can be reliably obtained.

In addition, when press-fitting the self-rotating helical pile of the present invention, a soil holding plate that is in contact with the ground surface is provided, and a pile support cylinder having a female thread that matches the male thread of the self-rotating helical pile is erected on this earth holding plate. By press-fitting the helical pile screwed into the support cylinder, a strong rotation is generated in the pile, and the rotation allows the helical pile to easily penetrate into the soil.

〔Example〕

FIG. 4 is an explanatory diagram showing an embodiment of the present invention, in which a pile connector 2 is fitted onto the head of a helical pile 1 having a spiral protrusion 1'' with a large advance angle, and the pile connector Next, a pile 3 is added to the top of the pile 2 via the rotary support part 2' and the rotary sharp part 3'' so that the helical pile work can rotate, and then a cap 4 is fitted on the top of the pile 3, and the cap 4 is A helical pile 1 is penetrated into the soil by providing a pulley 5 and winding up a wire rope 6 with one end fixed to the ground surface via the pulley 5 by a pile penetration wind def.

At this time, a soil retaining plate 9 is placed on the ground surface 8, this soil retaining plate 91 is made to hold the pile support tube 10 having a female screw, and the helical pile 1 is rotated into the soil via the pile support tube 10 having a female screw. Let's make it fit in.

FIG. 5 shows a case in which the hydraulic cylinder 11 is also used as a wave press-in device in the helical pile driving according to the present invention. Provides traction.

FIG. 6 shows a case where the wire rope 6 is wound in plurality, and in the case shown in the drawing, the winding station power can be reduced to 172.

In addition, Figure 7 shows another example of a wave force amplification device.
13 is a wave pulley for tightening the wire rope 6.

〔Effect of the invention〕

As described above, in the present invention, four spiral strips with a large advance angle are provided on the outer periphery of a round pile for driving, so when the helical pile is press-fitted, a rotational movement occurs naturally, and the helical pile is press-fitted while turning. The pile driving work is completed in an extremely good condition with no vibration and no noise, and even after driving, the presence of spiral ridges provides a great bearing capacity, making it an excellent natural rotation press-in hole and pile press-in method. .

In addition, if a fixing member is attached to the top of the pile after driving, or a concrete plate is placed on the top of the pile to prevent the pile from rotating, it is possible to prevent the subsequent pile from turning. Since rotation can be easily controlled, this pile press-in method can reliably prevent pile settling due to natural rotation.

In addition, if you measure the pile press-in force with a load cell, etc., continue press-fitting until the desired pile bearing capacity is obtained, and stop press-fitting when the desired pile bearing capacity is obtained, all piles will be the same. It is also possible to drive into bearing capacity, making it an excellent pile press-in method with no waste.

In addition, a soil retaining plate is provided, and a pile bearing tube with a female thread that matches the male screw of the helical pile is erected on the soil retaining plate, and if the helical pile is press-fitted with the helical pile screwed into this pile bearing tube, the pile will be piled up. This is an excellent pile press-in method that allows stable press-in due to the guiding action of the bearing cylinder.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is an enlarged explanatory view of the spiral convex ridge of the helical pile of the present invention, FIG. 2 is an explanatory view of component force on a helical slope, and FIG. Figure 4 is an explanatory diagram of a helical slope, Figure 4 is an explanatory diagram showing the method of press-fitting a helical pile of the present invention, Figure 5 is a front view of an example of a helical pile driving machine according to the present invention, and Figure 6 is a wire rope. Figure 7 is an explanatory diagram showing another example of how to install a wire rope, and Figure 8 is an explanatory diagram showing another example of a wire rope wave force amplification method. Figure 8 is a diagram showing a fixing member attached to the head of a helical pile that has penetrated into the soil. It is an explanatory diagram showing a state. ■...Spiral pile, 1'...Convex strip, ■"...Fixing member,
9. Earth holding plate, 10. Pile support tube. December 27, 1986

Claims (1)

[Scope of Claims] 1. A large advance that causes rotational movement around the pile axis as the penetration into the ground progresses due to a pressing force applied in the axial direction of the pile along the outer periphery of the round pile for driving. A naturally rotating press-in pile characterized by having spiral protrusions with corners. 2 Along the outer periphery of the round pile for driving, a helical shape with a large advance angle that causes rotational movement around the pile axis as the penetration progresses into the ground due to the pressing force applied in the axial direction of the pile. After a self-rotating helical pile with convex ridges is inserted into the ground to a required depth, a fixing member is attached to the top of the pile to prevent subsequent natural rotation of the pile. Pile press-in method. 3 Along the outer periphery of the round pile for driving, a helical shape with a large advance angle that causes rotational movement around the pile axis as the penetration progresses into the ground due to the pressing force applied in the axial direction of the pile. When press-fitting a self-rotating helical pile with convex striations, the bearing capacity of the pile is calculated by measuring the press-in force, and the press-fitting is stopped when the bearing capacity reaches a predetermined value. Pile press-in method. 4 Along the outer periphery of the round pile for driving, a helical shape with a large advance angle that causes rotational movement around the pile axis as the penetration progresses into the ground due to the pressing force applied in the axial direction of the pile. When press-fitting a self-rotating helical pile with a protruding strip, a soil holding plate is provided, a pile support tube with a female thread that matches the male thread of the helical pile is erected on this soil press plate, and the pile support tube is screwed onto the pile support tube. A helical pile press-in method that is characterized by press-fitting a spiral pile.