JPS6051219A - Method and apparatus for formation of sand pile - Google Patents

Abstract

PURPOSE:To reduce the friction between the wall of a tube and sand by applying compressed air effectively by a method in which a water jet nozzle is provided to the lower part of the outer tube of a sand pile former, and the inside of the lower outer tube in the working region of a sand forcibly discharging and compacting part is saturated with water. CONSTITUTION:A sand pile former consists of a hollw tube 1 forming sand pile, a penetrator 2, a hopper 3, an air-tight valve 4, a compressed air supplying tube 5, an exhaust tube 6, an oil-pressure cylinder 7, a sand forcibly discharging and compacting part 8, an outer tube 9, and a water jet nozzle 10. In forming sand pile, water is jetted through the nozzle 10 from the tank 11, the valve 4 is closed while drawing the tube 1, compressed air is sent from the tube 5 into the hollow tube 1, sand in the tube 1 is pressed, and the sand in the tube 9 is forcibly discharged from the lower end of the tube 1 by the compacting part 8. The sand in the outer tube 9 below the part 8 is saturated with water.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a technique for constructing compacted piles in soft ground using sand or its analogues.

Technology for creating compacted sand piles by applying pressure to the sand surface inside the pipe and activating the sand forced discharge and compaction member installed at the lower end of the pipe during the drawing process of hollow pipes for sand pile construction. is known, but the present invention is such that the pressure of the air and the pushing force of the sand forced discharge/compaction member effectively act on the discharge and compaction of sand. The above feature is that the construction method involves pulling out the hollow tube for papermaking, applying pressure to the sand surface inside the hollow tube, and activating the sand forced discharge and compaction member at the lower end of the hollow tube. , In the process of creating a compacted sand pile, the sand in the pipe below the operating area of the forced sand discharge and compaction member is saturated with water.
The device consists of a hollow tube for sand pile construction with an internal pressure air device installed at the upper end, a forced sand discharge and compaction member operated by a forced vertical movement mechanism on the outer periphery of the lower end, and an outer tube that covers the outside of the hollow tube. It extends below the operating area of the sand forced discharge and compaction member, and a water injection nozzle directed into the pipe is provided in this extension.

The present invention will be specifically described below with reference to the drawings.

In the figure, l is a hollow pipe for sand pile construction, 2 is a penetrating machine, 3 is a hopper, 4 is an airtight valve, 5 is a compressed air supply pipe, 6 is an exhaust pipe, 7 is a forced vertical machine (for example, (hydraulic piston/cylinder device), 8 is a sand forced discharge/compaction member, and 9 is an outer pipe.

The outer tube 9 is longer than that of the conventional seeded one,
It extends in the trench below the working area of the sand forced discharge and compaction section 8, and IO is a water injection nozzle installed in the extension.

A plurality of water injection nozzles 10 are provided at intervals in the circumferential direction of the outer tube 9, and the water injection direction is horizontal or diagonally downward inward of the outer tube 9. Note that the water injection nozzle 10 may be an injection hole provided in an annular pipe.

The water jet nozzle IO spouts water that is sent from the tank 11 through the channel 13 by the pump 12 during sand pile construction.
When constructing a sand pile, the airtight valve 4 is closed while pulling out the hollow pipe l for sand pile construction (hereinafter simply referred to as hollow pipe 1), and compressed air is sent into the hollow pipe l from the compressed air supply pipe 5. , hollow tube 1
When the sand inside is pressurized, the sand is forcibly discharged from the lower end of the hollow tube 1 into the outer tube 9, so the water mentioned above is injected toward the sand and saturates it.

In this way, the sand in the outer tube 9 below the operating area of the sand forced discharge/compaction member 8 is pushed from above with the gap filled with water, and the sand is sequentially pushed from the lower end of the outer tube 9 to the ground. It is expelled inside.

It is preferable to keep the amount of water added from the water injection nozzle lO to the minimum necessary, but if this is not possible, the amount of water added may be controlled as follows.

The amount of sand discharged from the lower end of hollow tube 1 per unit time is Δ
When SL is the amount of water added per unit time and ΔQ is the amount of water added per unit time, ΔQ is controlled so that it becomes a constant based on the pore ratio of sand. ΔSL is detected by a so-called sand level meter 14. However, ΔQ is detected by a flow meter 15 provided in the flow path 13, these detection signals are sent to a meter 16, and a control valve 17 provided in the flow path 13 is controlled by a control signal issued from there.

When the sand in the hollow tube 1 is gone, the drawing of the hollow tube 1 is temporarily stopped, the airtight valve 4 is opened, and the hollow tube 1 is removed from the hopper 3.
Sand is replenished into the tank, but in such a case, the switching valve 18 is controlled to stop adding water.

As mentioned above, in the method of the present invention, during the sand pile construction process, the sand in the pipe below the operating area of the forced sand discharge and compaction member is saturated with water, so the pressure of the pressurized air is applied to this hydrated sand layer. As a result, effective pressurization is achieved without air leakage, and the friction between the hydrated sand layer and the water drainage pipe wall is reduced, and the pushing force of the sand forced discharge and compaction member is reduced. It acts effectively on the hydrated sand layer, and moreover, the sand in the operating area of the forced sand ejection and compaction member has a natural water content, and there is no problem in its forced ejection and compaction. Moreover, by using the apparatus of the present invention, the above-mentioned construction method can be carried out appropriately.

[Brief explanation of the drawing]

The drawing is an explanatory diagram of an embodiment of the device invention. In the figure, 1... Hollow pipe for sand pile construction, 4... Airtight valve, 5
... Compressed air supply pipe, 7... Forced 2 lower movement tJ! Accommodation, 8... Sand forced discharge and compaction member, 9... Outer pipe, l
O...Water injection nomel... Patent applicant: Fudo Construction Co., Ltd. Representative patent attorney: Hiroshi Sometani

Claims (1)

[Claims] 1) While pulling out a hollow pipe for constructing a sand pile, pressurized air is applied to the sand surface inside the hollow pipe, and a sand forced discharge and compaction member at the lower end of the hollow pipe is operated. , a sand pile construction method characterized by saturating the sand in the pipe below the operating area of the sand forced discharge and compaction member with water in the process of constructing the compacted sand pile. 2) A pressure air device inside the pipe is installed at the upper end.A forced sand discharge and compaction member operated by a forced vertical movement mechanism is installed on the outer periphery of the lower end of the hollow pipe for sand pile construction. 1. A sand pile construction device, which extends below the operating area of a forced discharge/compaction member, and is provided with a water injection nozzle directed into the pipe at this extension.