JPH0243844B2 - DOSHITSUCHOSASHIKENHOHO - Google Patents

Description

[Detailed Description of the Invention] (a) Technical Field of the Invention The present invention is suitable for application to the case of investigating the soil quality of the ground at the construction site during ground modification, cast-in-place construction, underground structure construction, etc. Concerning soil investigation test methods.

(b) Technical background When conducting ground modification or constructing cast-in-place shafts, investigating the soil quality of the ground is an essential requirement to ensure proper construction.

(c) Conventional technology and problems Figure 4 is a diagram showing the condition when a modified ground was constructed underground based on the conventional soil investigation test method, and a is a diagram based on a standard penetration test in the depth direction of the ground. Soil survey map showing the N value, b is a diagram showing the shape of the artificial ground designed based on the soil survey map in a, c is a case where the artificial ground is constructed using the excavation method using a jet jet based on the design in b This is a diagram showing the ground that was actually constructed.

Conventionally, as this type of soil investigation test method, a method of determining the soil quality by determining the N value using a standard penetration test has been well known. However, with this method, the N value is measured only at predetermined intervals (usually 1 m pitch) in the depth direction of the ground, so it is difficult to capture subtle changes in the strata in the ground. Therefore,
N determined by the standard penetration test shown in Figure 4a
Even if the shape of the artificial ground 1 to be constructed is designed based on the values as shown in Fig. 4b, the shape of the ground 1 to be actually constructed will be different from the designed shape as shown in Fig. 4c. It will be extremely uneven compared to DS (this example shows a case where the ground 2 is excavated in a cylindrical shape using a jet stream and then filled with a solidification material such as cement milk). . This is due to the fact that the standard penetration test can only measure the soil quality at a predetermined pitch, making it impossible to understand in detail the continuous ground conditions that actually exist in the ground. It is something to do. Although this problem can be solved by shortening the measurement distance of the N value in the standard penetration test to some extent and investigating the soil texture in detail, the penetration test itself requires a large number of borings, which reduces the number of man-hours and construction period. Problems arise and there are drawbacks that make it not a very realistic solution.

In addition, when a highly uneven ground 1 as shown in Fig. 4c is constructed, if the ground 1 is to be continuous in the horizontal direction in the figure, it is necessary to The construction must be designed with a sufficient safety factor in mind, resulting in extremely wasteful construction in terms of materials, man-hours, and construction period.

In addition, in the case shown in FIG. 4c, as already mentioned, we have described the case where the artificial ground 1 is constructed by the excavation method of excavating the ground by ejecting a jet jet into the surrounding ground, but the method of excavating the ground and The same holds true even when the purpose of excavation changes, and there has been a strong desire to develop a soil investigation test method that can continuously and relatively easily investigate soil conditions.

(d) Purpose of the Invention In order to eliminate the above-mentioned drawbacks, the present invention is capable of continuously and easily determining the soil condition of the ground, and it is possible to improve the construction of underground structures such as artificial ground in terms of materials, man-hours, etc.
The purpose of this invention is to provide a soil investigation test method that enables construction without wasting time.

(e) Structure of the Invention In other words, the present invention involves drilling a pilot hole in the ground where the soil quality is to be investigated and testing, and supplying excavated water through the drilled pilot hole under the same excavation conditions. The ground is excavated by ejecting water over a range, and when the excavation is completed,
It is configured to measure the excavated shape of the excavated ground and determine the soil quality of the ground from the obtained excavated shape.

(f) Embodiments of the invention Hereinafter, embodiments of the invention will be specifically described based on the drawings.

Figure 1 is a process diagram showing an example of the soil investigation and testing method of the ground according to the present invention, Figure 2 is a diagram showing a method for determining the soil quality as seen from the shape of excavation of the ground, and Figure 3a is the artificial structure to be constructed. FIG. 2 is a diagram showing the design shape of the ground, and b is a diagram showing the results of a soil investigation test on the soil quality of the ground on which the artificial ground will be constructed using the soil investigation test method according to the present invention.

When investigating and testing the soil quality of the ground 2 according to the present invention, as shown in FIG.
excavate using. Once the pilot hole 3 has been excavated, as shown in FIG. 1b, high-pressure water 6 is applied from the nozzle 7 attached to the excavation pipe 5 to the surrounding ground while rotating the excavation pipe 5, that is, the nozzle 7 in the horizontal direction. 2 and excavates the surrounding ground 2 (the excavated soil generated during excavation is discharged to the outside through the excavation pipe 5 in the form of a slurry along with muddy water). This excavation operation is performed by moving the nozzle 7 vertically over the range W in which the soil quality is to be investigated, as shown in Fig. 1c, but the excavation conditions at this time are the same throughout the entire investigation range W. is maintained. That is, the ground 2 surrounding the high pressure water 6 from the nozzle 7
All parameters that affect ground excavation, such as the jetting pressure toward the ground, the jetting amount, the vertical movement speed of the nozzle 7, and the rotational speed of the nozzle 7, are kept under the same conditions. As a result, the surrounding ground 2 is excavated under completely equal conditions over the range W, but the excavation shape SHP of the ground that has been excavated in this way can be measured using an ultrasonic sensor attached to the excavation pipe 5, as shown in Fig. 1d. The distance is measured by measuring the distance between the excavation pipe 5 and the excavated ground wall surface 2a using the distance device 9.

The excavation shape is determined by measurement using the ultrasonic distance measuring device 9.
As shown in Fig. 2, when SHP is determined, the distances L1, L2, and L3 from the pilot hole center CL correspond to the hardness of the relevant part of the ground. That is,
This is because, since excavation was carried out under the same excavation conditions, areas with soft ground were excavated a longer distance from the center CL, while areas with hard ground were excavated only a short distance from the center. In addition, the tangent angles α1, α2, α3 in the excavation shape SHP
is a form that differentiates the excavation shape SHP, so it indicates the degree of change in the hardness of the ground; the larger the angle α, the less the change in the hardness of the adjacent ground, and the smaller α, the less the change in hardness. becomes larger.

In this way, for example, when constructing the artificial ground 1 having the design shape DS as shown in FIG. 3a on the same ground as the ground 2 shown in FIG. Assuming that the survey test results shown in (the jetting pressure of drilling water such as high-pressure water 6 from the nozzle 7 during the test are, for example, 200 Kg/cm ² ), based on these results, during actual excavation, The ejection pressure of excavated water to be ejected from the pipe 5 is determined by the depth
Since the depth from PA to PB has been excavated roughly according to the design value, the ejection pressure is set at 200Kg/cm ² , the same as during the test, and from depth PB to PC, it is determined that there is a hard stratum, so the ejection pressure is set at 300Kg. /cm ² to maintain the design shape DS during actual excavation, and taking into account the safety factor from depth PC to PD, similarly set it to 300Kg/cm ² , and from depth PD to PE, Since it is determined that there is a soft stratum, the ejection pressure will be reduced to 100Kg/cm ² . From depth PE to PF, it is determined that there is a hard stratum, so the ejection pressure will be increased to 500Kg/cm ² to ensure the design shape DS. In this way, excavation conditions can be set in detail according to the soil quality, so
During actual excavation, it is possible to construct artificial ground with a shape that is almost close to the designed shape DS.

(g) Effect of the Invention As explained above, according to the present invention, a pilot hole 3 is excavated in the ground where the soil quality is to be investigated and tested, and high pressure water 6 etc. is excavated through the excavated pilot hole 3. Excavating the ground to be investigated by spouting water over the range W where the soil quality is to be investigated and tested under the same excavation conditions, and when the excavation is completed, measuring the excavation shape SHP of the excavated ground,
Since the soil quality of ground 2 is judged from the obtained excavation shape SHP, the distance L1 from the center CL,
By determining the tangent angles α1, α2, α3, etc. of the curves representing L2, L3, etc. and the excavation shape SHP, it is possible to know the soil quality of the strata at any location continuously and in detail, and it is possible to know the soil quality of the strata at any location, which is different from the conventional standard penetration test. This makes it possible to easily detect subtle changes in soil quality that cannot be obtained with conventional methods.

In addition, in order to be able to know the soil quality in detail,
When constructing underground structures such as artificial ground, excavation conditions can be set in detail, making it possible to construct structures close to the original design shape DS, and improving construction costs that previously had to be overestimated. The safety factor can also be set to an appropriate value, making it possible to save materials and significantly shorten man-hours and construction period.

Furthermore, by using the N value of the conventional standard penetration test in combination, it is of course possible to understand the soil quality more accurately.

[Brief explanation of drawings]

Figure 1 is a process diagram showing an example of the soil investigation and testing method of the ground according to the present invention, Figure 2 is a diagram showing a method for determining the soil quality as seen from the shape of excavation of the ground, and Figure 3a is the artificial structure to be constructed. Figure 4 shows the design shape of the ground; b is a diagram showing the results of a soil survey test of the ground on which an artificial ground will be constructed using the soil survey test method according to the present invention; 2 is a diagram showing the condition when the modified ground was constructed underground, where a is a soil survey map showing the N value from a standard penetration test in the depth direction of the ground, and b is a diagram designed based on the soil survey map in a. A diagram showing the shape of the artificial ground, c is a diagram showing the actually constructed ground when the artificial ground was constructed by the excavation method using a jet jet based on the design of b. 2...Ground, 3...Pilot hole, 6...High pressure water (excavation water), W...Range, SHP...Drilling shape.

Claims (1)

[Claims] 1. Excavating the ground by drilling a pilot hole in the ground where the soil quality is to be investigated and tested, and squirting the excavated water through the drilled pilot hole over the area where the soil quality is to be investigated and tested under the same excavation conditions. When the excavation is completed, the excavation shape of the excavated ground is measured, and the soil quality of the ground is determined from the obtained excavation shape.