JPS5838569B2 - Ground consolidation method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a ground consolidation method.

BACKGROUND ART Conventionally, a so-called deep mixing ground improvement method has been implemented in which cement-based solidifying agent milk is discharged into soft and viscous ground and stirred to solidify the ground.

Regardless of its economic efficiency, this ground improvement method has the characteristic of improving soft and viscous ground into relatively strong ground, but on the other hand, the size is determined by the construction unit, and generally it is a few IO meters. The improved ground (cube) becomes one solidified ground, and the difference in soil strength with the surrounding unimproved ground becomes significant, and if subsidence (especially uneven settlement) occurs in the unimproved ground below, the improved ground above becomes solidified ground. It has been found that there are many problems in the design and analysis of improved ground, such as the risk of collapse.

In particular, if the construction is done on the foundation ground of a breakwater, which is one of the port structures, there is little risk that damage to the breakwater will directly affect human life, so it should not be a big problem. Recently, when construction is carried out on the foundations of important offshore structures, such as improvements to the base magnetic ground, the collapse of the foundations can directly affect human life, so it has recently begun to become a serious problem.

The present invention provides a construction method that improves the conventional ground consolidation method in view of the above-mentioned drawbacks. Instead of solidified ground, we created a type of artificial compact rough stone simulated ground that resembles tightly stacked megaliths to improve consistency with the surrounding unimproved ground.

In other words, if the ground is consolidated using the conventional deep mixing method, cracks that occur for some reason will further expand due to earthquakes and develop into a state that cannot be repaired, but with this method, the consolidated ground will be susceptible to earthquakes, etc. In the same way that a rough stone layer forms a new equilibrium state even if the ground is deformed by It does not cause any damage.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

Two independent lines of kneading equipment are provided on a workbench or a predetermined workspace (not shown).

This device consists of 1 water, 2 and 3 solidifying materials, and 4 other mixed materials.
It is composed of storage tanks for admixtures (for example, admixtures such as fluidizers and water-reducing agents), a measuring device 5 for these, a mixer 6, and an agitator 7.

FIG. 1 is a flow chart of the above device. These 2
An electromagnetic valve 8 is installed at each outlet of the agitator 7, which is the final equipment of the kneading equipment in the series, and the mixture is further kneaded via a pressure pump 9 and a flow meter 10 in two independent series to the ground agitator 11 underground via a pipe. of caking agent milk is pumped.

At this time, by freely controlling the opening and closing of the respective electromagnetic valves 8, the respective pumping amounts of the cement-based caking material milk and the expandable caking material milk are freely managed and are pumped alternately at predetermined intervals.

At this time, depending on the ground, after passing through the electromagnetic valve 8, the pipes may be combined into one pipe, and two types of caking agent milk may be sent in pulses through one pipe using an L-series pressure pump 9 and a flow meter 10. is also possible.

Then, the caking material milk is discharged from the tip of the ground agitator 11 into the ground B in the sea water A and stirred.

The ground agitator used here can be any of those used in the existing deep mixing method, and after the agitator is rotated forward to dig deep, the agitator is rotated in the opposite direction to pull out the solidified material from the tip. When it is discharged into the ground, it is stirred by an agitator, and the caking agent milk is evenly mixed into the ground.

In this way, during the hardening process of the caking agent milk, the ground from which mainly the cement-based caking agent milk is discharged becomes a unified solid lump, and the ground from which the expandable caking agent milk is discharged and stirred becomes semi-solidified. Due to the expansion action in this state, it solidifies into a strong lump with some cracks.

In this way, the area where the ground has been improved becomes a consolidated ground with arbitrary cracks in a layered or mosaic pattern.

12 in FIG. 2 shows an example of a layered crack.

One of the two lines of independent crosstalk devices uses a cement-based solidifying material 2, and the other uses an expandable solidifying material 3 to perform crosstalk.

The cement-based solidifying material 2 used here can be any commercially available cement, including ordinary Portland cement, with a water-cement ratio of 80% and an amount of boiled cement of 100-150 per cubic meter of ground. The -axial compressive strength of ordinary soft cohesive soil (so-called sludge) is about 40.9/crrL on average, as shown in FIG.

In addition, any commercially available expandable material made of aluminum, lime, or gypsum can be used as the expandable solidifying material 3. When the amount used is 150 to 45 OK1II+, the improvement of sludge - the axial compressive strength is equivalent to that of cement-based solidifying material, as shown in Figure 4, and the volume change of the expanding layer changes depending on the amount of expanding material used. Although it depends on the situation, it is 5 to 6% as shown in Fig. 5.

Note that the kneading water used here may be either fresh water or seawater, and other mixing materials such as a fluidizing agent and a water reducing agent may be appropriately selected depending on the target ground and the consolidation material used.

As described above, according to the present invention, the following effects can be obtained.

■ By artificially creating cracks of arbitrary size and arrangement in a layered or mosaic pattern in the solidified ground, a tightly interlocking simulated rough stone layer is formed, and the behavior of the surrounding unimproved ground (e.g. earthquake (horizontal displacement or uneven settlement, etc.) and has high stability after tracking.

That is, by improving the soft sludge layer, a good rough stone layer with a large internal friction angle can be obtained.

■ After mixing the cementitious solidification material and the expandable solidification material independently using two independent mixing devices, the mixture is pumped and stirred into the ground via a solenoid valve installed in each. By controlling the opening and closing of electromagnetic valves, it is possible to easily and economically control the size and arrangement of cracks in consolidated ground.

By using appropriate positioning devices and moving devices, it is possible to continuously consolidate the entire improved ground, so that a soft sludge layer can be completely transformed into a good rough stone layer.

[Brief explanation of drawings]

Figure 1 is a flowchart of the crosstalk equipment, Figure 2 is a schematic diagram of layered cracks, Figure 3 is the experimental result of the unconfined compressive strength of Osaka Tsutsumi sludge using cement-based solidifying material, and Figure 4 is also an expansion diagram. FIG. 5 shows the experimental results of the volume change rate of the expansion layer due to the mixing of the expandable consolidation material. 1: Water, 2: Cement solidifying material, 3: Expandable solidifying material,
4: Admixture, 5: Measuring device, 6 Mixer (mixer), 1
: Agitator, 8: Solenoid valve, 9: Pressure pump, flow meter, 11: Ground agitator, 12: Layered crack,
A: Seawater, B: Ground.

Claims (1)

[Claims] 1 Two lines of compaction material kneading equipment are installed independently on the workbench.
■Kneading process using cement-based solidifying material in one series of equipment and expandable solidifying material in the other series of equipment, and electromagnetic valves installed next to each of these two independent series of agitators. After that, the mixed caking material milk is further pumped through a pressure pump and a flow meter to a ground agitator in the ground via a pipe, and the above two types of caking material milk are poured into the ground from the tip of the ground agitator. During the hardening process of the solidifying material, the milk of the cement-based solidifying material is discharged and stirred alternately, or in some cases simultaneously, as a result of the stirring process. The ground from which the caking agent milk has been discharged and stirred is solidified into a solid mass with cracks in some parts, and the scale and pattern of the cracks in the solidified ground are controlled by controlling the switching of the electromagnetic valve. A ground consolidation method that is characterized by the ability to