JPS5850216A - Improving work of soft ground - Google Patents

Abstract

PURPOSE:To obtain uniformly improved ground by forming sand piles while changing any one or both of the diameters and strengths of the sand piles according to the variations in the soil quality of ground to be improved. CONSTITUTION:While injecting water from a jet nozzle 6, a hollow tube 1 is penetrated to a given depth of soft ground by operating a penetration mechanism 5 and a piston cylinder 2. Then, sand is charged into the hollow tube 1 from a hopper 7 and the hollow tube 1 is raised while operating a sand discharging and compacting part 3, whereupon sand discharged from the lower end of the hollow tube 1 is compacted by the part 3 to form a sand pile.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a technique for completely improving soft ground by constructing a large number of sand piles in the soft ground.

The design of soft ground improvement work is determined based on the results of soil surveys at multiple locations within the improvement area.

In the past, if sand piles were built with the diameter and pitch given in the design, they would have a predetermined improved ground strength, so actual variations in the original ground strength would be directly reflected in the improved ground strength, resulting in a uniform ground. There was a problem that no improvements were made.

The present invention has been made in view of this point, and in order to uniformly suspend improved ground, either or both of the sand pile diameter and sand pile strength can be adjusted in response to changes in the soil properties of the original ground. A distinctive feature is that the construction of each sand pile is carried out while making changes.

Fig. 1 is a schematic diagram showing a comparison between the conventional technology and the present invention, where a is the original ground strength according to the soil survey, b is the original ground strength for design C, C is the target improved ground strength, and d is the actual improved soil strength, and in the conventional technology ([), d
d varies as well as a, whereas in the present invention of the button, d coincides with C, indicating that the ground is uniformly improved according to the present invention.

Figure 2 is an example of sand pile construction equipment used in the construction method of the present invention?
In this figure, 1 is a hollow pipe for sand pile formation, 2 is a hydraulic piston cylinder device, 3 is a sand discharge/compaction member, 4 is an outer pipe, 5 is a penetrating machine, and 6 is a fountain. nozzle,
7 is a hopper, 8 is an air valve, and 9 is a compressed air supply pipe.

To create a sand pile using this device's sound, first the hollow tube l is penetrated into the soft ground to a predetermined depth. - Penetration becomes easier if the two cylinder devices are also activated.

Next, sand is put into the hollow tube 1 from the hopper 7, and when the hollow tube 1 is raised continuously while operating the sand discharge/compaction member 3, sand is discharged from the lower end of the hollow tube 1. The sand is compacted by a sand discharge/compaction member 3 to create a sand pile.

The diameter of the sand pile being constructed is calculated based on the values obtained from the sand level gauge that detects changes in the sand surface inside the hollow pipe 1 and the depth gauge that detects the bottom depth of the hollow pipe 1. Since this point is well known, detailed explanation will be omitted.

The actual strength of the ground at the sand pile construction site can be detected by the hydraulic pressure of the piston/cylinder device 2, but it can also be detected by installing a stress measuring gauge, load cell, etc. at an appropriate location on the sand pile construction device.

When changing the sand pile diameter in response to variations in the original soil strength, the pile diameter should be made smaller than the standard design pile diameter in areas where the actual soil strength is greater than the design original soil strength.
In addition, the pile diameter is increased in places where the actual ground strength is low, but this change in pile diameter is due to the drawing speed 11- of the hollow tube 1.
This can be done by changing the diameter of the sand pile, or by spraying water sound from the fountain nozzle 6 onto the ground around the hollow pipe 1 and temporarily weakening the surrounding ground in a limited area. All measures to facilitate diameter expansion may be taken.

Next, when changing the sand pile strength in response to variations in the original ground strength, in places where the actual original ground strength is greater than the design original ground strength, the sand pile robbery km should be Also, in places where the actual ground strength is low, the strength of the sand piles can be quite loud. However, this change in the strength of the sand piles is
When using the sound of the sand pile making device shown in Fig. 2, this can be done by changing the stroke length of the sand discharge/compaction section 3, the number of times of lifting and lowering per unit time, and the repeated lifting and lowering.

Ru.

Detection of the stroke length of the sand discharge/compaction member 3 is accomplished by using a number of proximity switches operated by operating pieces provided on a part of the piston rod that moves up and down together with the sand discharge and compaction member 3 at the lower end or outside of the hollow tube 1. This can be achieved by arranging switches on the tube 4 at regular intervals, configuring a potentiometer circuit with each switch and a resistor connected between the switches, and detecting changes in the output voltage of this circuit. Also, the speed of elevation can be detected based on the hydraulic flow rate.

As is clear from the above explanation, according to the present invention, the original ground with uneven strength is improved to the ground that has the required strength in a uniform state, so that quality is guaranteed and the improved ground is provided without sagging. be able to.

In addition, although the previous description has been about ground improvement using sand piles, gravel and crushed stone can be used instead of sand.

Mine slag 1 Lime and other sandy materials can be used, and these? The present invention is also applicable to the case where it is used.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram comparing the prior art and the present invention, and FIG. 2 is a schematic diagram showing an example of a sand pile building apparatus used in carrying out the present invention. In the drawings, 1: Hollow 1.2: Piston/cylinder device,...
Agent Patent Attorney Hiroshi Sometani

Claims (1)

[Claims] In the method of completely improving soft ground by constructing a large number of sand piles in soft ground, in order to obtain a uniform improved ground, the sand pile diameter and sand pile strength should be changed depending on the changes in the soil texture of the original ground. Or, a soft ground improvement method characterized by constructing each sand pile while changing the hirakata.