JPS5819454B2 - Prestressed concrete knot pile manufacturing method and its equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a prestressed concrete method characterized in that when prestress is introduced into the concrete by a PC steel rod by demolding the formwork of a concrete joint pile, the formwork between the sections is slightly slid in the direction of introduction. This invention relates to a knot pile manufacturing method and its equipment.

Ready-made concrete piles (hereinafter referred to as joint piles) with enlarged cross-sections (joints) at appropriate intervals exhibit bearing capacity extremely efficiently, and when used as friction piles in soft ground, they can economically build strong foundations. This is a foundation pile with excellent performance.

These joint piles are normally made of reinforced concrete, but in order to increase earthquake resistance as foundation piles, making them made of prestressed concrete is very important in terms of increasing the functionality of the product.

When manufacturing prestressed products using the pretension method in a factory, there are two methods: (1) long line method (pulling the PC steel wire on a bench), and (2) individual formwork method (fixing the PC steel wire in individual formworks). Although there are other methods, method (2) above is preferable because of the need to produce in large quantities within a certain area.

In prestressed concrete, prestress is introduced into the concrete when the formwork is removed.

In this process, the reaction force of the PC steel wire is held in the formwork until the concrete achieves the required strength, but once the concrete has hardened, the reaction force is held in the concrete.

During this introduction, the formwork is released from compressive force, so it tries to stretch by an amount of elasticity.

Conversely, the concrete tends to contract due to the new compressive force acting on it, causing a shift between the formwork and the concrete.

If the cross section of the product is uniform, there will be no problem in the occurrence of misalignment between the formwork and concrete once the adhesion between the formwork and concrete is released during the prestress introduction work.

If the cross section of the product is not uniform, such as a knotted pile, the knots will prevent the formwork and concrete from slipping during prestressing and demolding work, which may cause damage to the concrete at the knots and prevent work. It's dangerous.

The present invention solves the above-mentioned problems, has excellent work efficiency, reduces the weight and cost of formwork, and is suitable for mass production.Explaining an embodiment of the present invention shown in the drawings, Flanges of semi-cylindrical formwork 1', 1'2.
2 are tightened with bolts 3 to form a cylindrical formwork 1.

The semi-cylindrical formworks 1' and 1' each have a certain interval l.
The mold 4 between the semicircular parts, which is independent of the mold 1', is fitted and held in a slightly slidable manner.

As shown in FIG. 1, the holding device 5 has a small cylinder 6 protruding from the inner peripheral surface r of the formwork 1', and holds a washer 7 slidably inside the small cylinder 6. A flange 6' is provided at the inner end, the inner end of a bolt 8 provided on the washer 7 is welded and fixed to the outer surface of the inter-part formwork 4, and a spring 9 is interposed between the flange 6' and the washer 7, By pressing the washer 7 outward with the force of the spring 9, the peripheral edges 4', 4' of the inter-part formwork 4 are crimped to the inner circumferential surface 1'' of the cylindrical formwork 1, and the flange 6' and bolt 8 are The inter-part formwork 4 can be slidably held along the inner circumferential surface r by the gap t.

The reference numeral 10 in the figure is a spring plate fixed to the inner circumferential surface 1'' for automatically returning the inter-part formwork 4 to its original position.

Reference numeral 11 denotes a spring plate tip clamping fitting provided on the outer surface of the mold frame 4.

The inter-part formwork 4 is made of a material such as thin steel plate, wood, hard rubber, plastic, or other material that is lightweight and strong enough to withstand concrete press-in pressure.

In the present invention, a PC steel bar 12 is supported at one end of the cylindrical formwork 1, the steel bar 12 is pulled using the other end of the formwork 1 as a fulcrum, and then fixed in the formwork 1. After filling and hardening concrete into the interval 1 part of the cylindrical formwork 1 and the inside of the formwork 4 between the parts shown in FIG. Flange 2
．． When the bolts 3 of 2 are removed, the PC formed by the cylindrical formwork 1
The bearing capacity of the steel rod 12 is lost, at which point prestress is introduced into the concrete.

When introducing this prestress, the cylindrical formwork 1 and Conch'J
However, due to the sliding between the cylindrical formwork 1 and the inter-part formwork 4, the shearing phenomenon occurs without damaging the concrete at the joints, and the prestress introduction work is completed. do.

Since the present invention is based on the above-described method and apparatus, the prestressed concrete joint piles 14 can be manufactured safely and quickly without damaging the joints 13, making it suitable for mass production.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing a prestressed concrete gnarled pile manufacturing apparatus of the present invention, FIG. 2 is a longitudinal cross-sectional view taken along line A-A in FIG. 1, and FIG. 3 is a side view of the prestressed concrete gnarled pile. 4... Partial formwork, 1... Cylindrical formwork, r... Inner peripheral surface, 13... Nodes, 14... Concrete joint piles.

Claims (1)

[Scope of Claims] 1. Prestressed concrete characterized in that when prestress is introduced into the concrete by PC steel rods 12 by removing the formwork of concrete joint piles 14, the inter-part formwork 4 is slightly slid in the introduction direction. Knot pile manufacturing method. 2. A prestressed concrete joint consisting of a device 5 for holding the inter-part formwork 4 in a slightly slidable manner on the inner peripheral surface 1'' of the cylindrical formwork 1, and a structure in which the inner peripheral surface 1'' directly contacts the outer peripheral surface of the joint 13. Pile manufacturing equipment.