JPH0411111A - Ground improvement process - Google Patents

Abstract

PURPOSE:To prevent the liquidizing phenomenon at the time of earthquake and to reduce the degree of compression settlement by installing a water pump connected to an exhaust pipe on the bottom of a pipe body installed in a ground, and by intermittently pumping up underground water in the pipe body. CONSTITUTION:A steel piped deep well 1 on which multiple permeable slits are opened, is buried in a ground. A water pump 2 provided with a control unit 3 is installed on the bottom of the deep well 1. The control unit 3 is connected to a control board 31 on the ground as well as to a power source, while the storage pump 2 is connected to an exhaust tube 21. When it is detected by a water level sensor, that the level of underground water reaches no less than a preset level, the water pump 2 is actuated, and the underground water flown in from the permeable hole of the deep well 1 is discharged from the exhaust tube 21 to the outside. At the time, intermittent pumping up is carried out by automatically actuating or stopping the water pump 2 in a preset cycle.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention stabilizes the ground by installing a deep well in soft ground such as sandy soil and pumping water intermittently in a certain cycle. (Conventional technology) As a method for improving soft ground such as sandy soil, the deep well method has traditionally been used.

In this construction method, a pipe with a strainer is inserted into the ground to be improved to a predetermined depth, and groundwater flowing into the pipe is pumped to the surface using a pump.

<Object of the present invention> The present invention is an improvement of the deep well construction method,
By pumping water intermittently in a fixed cycle, it is possible to compact the ground, increase its density, and more effectively prevent liquefaction of soft ground during earthquakes or reduce compression settlement. The purpose is to provide a ground improvement method that can be used.

<Description of the present invention> The present invention will be explained in detail below.

(A) Deep Well For the deep well 1, for example, a steel pipe 11 used in an ordinary strainer as shown in FIG. 3 is used.

A plurality of water permeable slits 12 are provided in this steel pipe 11.

Further, a porous concrete vibe 13 as shown in FIG. 4 can also be used.

In addition, any material can be used for the deep well 1 as long as it has water permeability.

In addition, please attach a filter etc. to the outer circumferential surface of the deep well 1 in advance (or fill the gap with the hole wall with filter material when burying the deep well 1) to prevent the water permeation hole from clogging. do.

<Exposure> Lifting Pump The lifting pump 2 can be a submersible pump, a Hugal pump, a high-head pump, etc., which are commonly used in deep wells, but the model is not particularly limited.

<C> Control unit The control unit 3 is a device for automatically operating and stopping the water pump 2.

The control unit 3 is composed of a group of known devices such as a water level sensor, a timer, and a pump operation switch.

<Construction method> Next, a method for constructing the deep well 1 will be explained.

First, as shown in Figure 5, in the ground to be improved,
Deep wells 1 are buried at a predetermined pitch using a construction machine that does not disturb the ground (for example, an auger type construction machine 4).

At this time, a water pump 2 is installed at the bottom of the deep well 1, and a control unit 3 is attached to this water pump 2.

The control unit 3 is connected to a control panel 31 on the ground and a power source so that remote control such as adjustment can be performed.

Furthermore, a drain pipe 21 communicating with the outside of the deep well 1 is connected to the pump 2 .

<Action of the present invention> Next, the operation of the present invention will be explained.

A water level sensor detects when the groundwater level rises above a certain level.

Next, the water pump 2 is activated by the sensing signal,
Groundwater that has flowed in through the water permeation hole of the deep well 1 is discharged to the outside through a drain pipe 21.

At this time, the timer is automatically turned on at the same time as the water pump 2 is activated.

When the timer turns OFF, the water pump 2 automatically stops.

If the groundwater level rises again, the above operations will be repeated.

In this way, the water pump 2 operates and stops in a fixed cycle, and pumps water intermittently.

As a result, groundwater is pumped effectively, and as shown in Figure 2, the effective confining pressure e after the water level drops increases significantly compared to the effective confining pressure e of the ground at the initial water level, and The aim is to increase the density of

FIG. 6 is a graph showing the test results of the relationship between the number of repeated pumping of groundwater and ground density.

It can be seen that the density of soft ground increases as the number of repetitions of groundwater pumping increases.

<Effects of the Present Invention> Since the present invention has been described above, the following effects can be expected.

That is, the present invention operates and stops the water pump in a fixed cycle to pump water intermittently.

As a result, groundwater can be pumped more effectively than the conventional deep well method.

Therefore, the effective confining pressure after the water level drops increases significantly compared to the effective confining pressure of the ground at the initial water level, and it is possible to increase the density of the soft ground.

Therefore, it is possible to prevent liquefaction of soft ground during an earthquake or reduce compression settlement more effectively than before.

Figure 5

[Brief explanation of the drawing]

Fig. 1.2 Diagram of ground stress due to the configuration of the present invention and ground improvement Fig. 3.4: Explanatory diagram of deep well pipe body Fig. 5: Explanatory diagram of construction method Fig. 6: Repeated number of pumping of groundwater, Graph showing the relationship with ground density Applicant: Daihide Construction Co., Ltd. −

Claims (1)

[Claims] (1) A pipe body with permeable holes on the circumference is installed in the ground to a specified depth, a lift pump is installed at the bottom of the pipe body, and a drainage pipe that communicates with the outside of the pipe body is connected to this lift pump. A ground improvement method characterized by pumping up groundwater in the pipe intermittently by starting and stopping a water pump in a fixed cycle.