JPH10102478A - Deep mixing method with method for judging arrival on sea bottom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deep mixing method which is carried out by adding a bottom arrival item to construction control items. SOLUTION: Penetrating speed of an excavation agitator axis, the time it takes for the axis to penetrate, and the depth of the tip of the axis are measured at an interval of unit time at the first construction of an improved column until the lowermost agitator impeller 4 of the agitator reaches the supporting ground to form a graph, whereby a reference diagram for judging the arrival of axis on the sea bottom. And thereafter, the improved column is constructed with reference to the reference diagram and measured values during the construction are taken up on real time to form a reference diagram of the arrival of the column on the sea bottom so that the construction is performed by judging the arrival on the bottom according to the reference diagram of the arrival of the column.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deep mixing method for construction on land or sea, and a method for deep mixing processing with a method for judging a bottom by adding a landing item to a construction management item. About.

[0002]

2. Description of the Related Art Conventionally, the deep mixing treatment method has been performed on land or at sea, and has achieved good results. Until now, the deep mixing method was mainly used to construct temporary structures such as non-slip of embankment, so it was not a problem whether landing on the supporting ground was appropriate. However, in recent years, as shown in FIG. 4, for example, it is a realistic study subject to use the improved ground 10 in which the improved columns are continuous in a plane as a permanent foundation of the structure 12. The landing item for confirming that the vehicle has reached the underground supporting ground 11 has become important in construction management.

[0003] However, conventionally, the management of the landing item is not performed. At best, the reading of the oil pressure gauge or ammeter of the rotation motor (hydraulic motor or electric motor) of the processing machine,
The sole is simply controlled based on the reading of the elevating speedometer of the processor. In other words, one improved pillar was experimentally constructed in a place where the depth of the supporting ground was found by a geological survey (boring survey), and the construction data (penetration speed, (Measurement value of oil pressure meter or ammeter). In particular, the penetration speed when landing,
And read the measured value of the oil pressure meter or ammeter of the processing machine rotation motor, to obtain each measured value until it is assumed that the landing state,
The required time indicated by the above-mentioned measured value until the landing is determined. In actual construction, when the above-mentioned penetration speed and the “specific measurement value” of the oil pressure gauge and the ammeter of the processing machine rotation motor continue for “a certain time (second)”, the landing is defined.
The above “specific measurement value” and “certain time” are, for example, N
The penetration speed at the value 30 is specified to be 0.1 m / min or less, and the case where the specific penetration speed continues for 90 seconds or 400 seconds is uniquely determined as the landing.

[0004]

As a general rule, the bottom is defined as a cross-sectional area of a predetermined size of the improved column (for example, a diameter of the stirring blade per axis is 1 m and a wrap length of 20 cm is 2 cm).
In the case of the axial method, a state in which an area of 1.5 m ² is in contact with the supporting ground is determined based on a landing determination criterion.

There are various types of deep mixing machines,
FIG. 1 shows an example of the shape of a tip of a drilling blade and a stirring blade at the tip of a two-shaft type drilling and stirring shaft of a deep mixing machine. FIG. 2 shows a bottom of an improved column when the above-mentioned drilling and stirring shaft is used. FIG. Generally, a tip of a biaxial shaft when a part of two improved columns a, a formed by the biaxial agitating and excavating shafts 1, 1 is wrapped and the cross section has a shape accompanied by a gourd determination method. The shape is as follows in order to prevent interference between the stirring blades. For example, of the two axes arranged in parallel with an inter-axis distance of 800 mm, the excavating blade 2 at the tip of the excavating and stirring shaft on the left side in FIG. 1 is a blade that also functions as an excavating blade with a maximum outer diameter of 1000 mm and a stirring blade, On the other hand, the right excavation blade 3 has a small maximum outer diameter of 580 mm. However, the lowermost stirring blade 4 of the right excavation stirring shaft has a maximum outer diameter of 1000 mm, a height difference h upward from the tip of the excavation blade 3 at a height of 550 mm, and the left excavation stirring shaft 4 has a maximum height h of 550 mm. The stirring blade 2 is provided in a stepped manner at a position about 200 mm above the upper end. In addition, the stirring blades 6 above the lower connecting plate 5 are also installed in a stepped manner with the positions of adjacent stirring blades shifted vertically.

For this reason, the tip shapes of the two improved columns formed by the two excavating and stirring shafts 1, 1 are indicated by dotted lines a in FIG. 1 and FIG. , A ', the vertical cross section has a step. Therefore, the present invention provides a position where the step in the vertical cross-sectional shape is positively eliminated, that is, a state where the lowermost stirring blade 4 on the right side in FIG. 1 reaches the support ground 11 in FIG. 2 (the elliptical hatching in FIG. 2). Position) is defined as the bottom.

However, in the above-mentioned conventional landing management method, it cannot be confirmed at all whether or not the lowermost stirring blade 4 has reached the support ground 11, but only depends on the guess. Not only is it difficult to determine whether the vehicle has reached the support ground and has landed, because it is determined unambiguously by measuring a phenomenon in which "specific measurement values" continue for "a certain period of time". Since the continuation of “a certain time” is set longer than necessary as a rate, the time to construct one improved pillar (loss time) is eventually
Is lengthy and unreasonable.

[0008] Accordingly, an object of the present invention is to provide a more accurate prediction and confirmation of the depth of the supporting ground at the site during the construction of an improved pillar, and to provide a self-adherence judgment reference diagram prepared at the stage of the improved pillar construction. Therefore, it is possible to accurately judge the landing in real time on the basis of the method, and thereby to be able to perform the deep mixing processing method quickly, accurately and rationally.

[0009]

As a means for solving the above-mentioned problems in the prior art, a deep-layer mixing method with a landing determination method according to the present invention according to the first aspect of the present invention includes a method of mixing a drilling blade at the tip with a stirring blade. In the deep mixing process method of creating an improved pillar by penetrating the excavation and stirring shaft with wings to a predetermined depth in the ground and stirring and mixing the excavated in-situ soil and the stabilizer,
The measured values of the penetration speed, penetration time and penetration depth of the drilling and stirring shaft in the construction of the first improved column (or test digging) were measured every unit time until the lowermost stirring blade of the drilling and stirring shaft reached the supporting ground. Create a graph of the bottoming judgment criteria that was collected and graphed, and for the subsequent construction of the improved pillars, referring to the aforementioned bottoming judgment criteria map, collect each measured value during construction in real time and The method is characterized in that a bottoming reference map is created, and the construction is performed while determining the bottoming based on the drawing.

[0010] In the deep mixing method with the landing judgment method according to the second aspect of the present invention, the excavation and stirring shaft provided with excavating blades and stirring blades at the tip penetrates to a predetermined depth in the ground and excavates. In the deep-mixing method in which the improved in-situ soil and stabilizing agent are agitated and mixed to form an improved pillar, the depth of the underground supporting ground at the construction reference point (hereinafter referred to as the reference point) for survey boring conducted in advance. Is confirmed in advance based on the soil section, and the results of the above confirmation are used as preliminary knowledge, and the measured values of the penetration speed, penetration time, and penetration tip depth of the excavation stirring shaft in the construction of the first improved column near the reference point The bottom stirrer of the excavation stirrer shaft was measured and sampled every unit time until the bottom stirrer blade reached the support ground, and a graph was created to create a bottoming judgment reference chart. Refer to the bottom judgment standard diagram Above, to create their own wearing bottom criterion view were taken each measurement in the construction in real time, characterized by construction while determining the wear bottom based on FIG.

According to the second aspect of the present invention, the depth of the underground supporting ground is confirmed by arranging the improved pillar on the basis of a soil layer cross-sectional view of a geological survey (boring survey) conducted at a reference point before construction. It is characterized in that the depth of the supporting ground is determined in advance (preliminary knowledge). The setting of the landing standard in the invention according to claim 1 or 2 is characterized in that it is set based on the penetration speed of the excavation stirring shaft and the duration thereof in the own landing determination reference diagram created by the improved column construction. .

According to the first or second aspect of the present invention, the landing standard is set by a penetration depth from a change point of the penetration speed of the excavating agitating shaft in the own landing determination standard diagram created by the improved column construction. It is characterized by doing.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The deep-layer mixing method with the landing determination method according to the first and second aspects of the present invention,
As shown in FIG. 1, the excavating blades 2, 3 and the stirring blade 4,
The drilling and stirring shaft 1 provided with the drill 6 is penetrated to a predetermined depth in the ground, and the excavated in-situ soil and the stabilizing agent are stirred and mixed to form an improved column.

In this case, the bottom is defined as described above, as shown in FIG.
It is assumed that the lowermost stirring blade 4 on the middle right has reached the support ground 11. The method of managing the landing according to the present invention is broadly classified into test digging (also the first improved column digging) as in the invention of claim 1 and digging and stirring obtained by this test digging. The measured values of the penetration speed V of the shaft, the required time for penetration n, and the depth d of the penetration tip are measured by the lowermost stirring blade 4 of the excavation stirring shaft.
3. A method of creating a bottoming determination reference diagram which is collected and plotted (plotted) every second, for example, up to the bottoming condition at which the vehicle reaches the supporting ground, and a designer as in the invention according to claim 2. The depth of the underground supporting ground is confirmed in advance based on the longitudinal section of the ground that is known as the reference point of the geological survey (boring survey) provided by The measured values of the penetration speed V of the excavation agitating shaft, the required penetration time n, and the penetration tip depth d in the construction of the first improved column constructed near the point are measured by the lowermost stirring blade 4 of the excavating agitating shaft on the supporting ground. Until the landing condition reached, for example, 1
There is a method of creating a bottoming determination criterion diagram that is collected and plotted (plotted) every second. According to the latter method,
There is a certain and reliable procedure to advance the construction of the improved pillar by planning (foreseeing) the landing depth in advance. Both of the above two methods are common in providing a bottoming determination reference map which serves as basic data for the subsequent construction of the improved pillar. Therefore, very practical and correct data can be obtained as the data of the landing determination.

Next, the method for determining the landing by proceeding with reference to the landing determination reference diagram prepared as described above includes a method of determining the landing based on the penetration speed of the excavation stirring shaft and the duration thereof. There are two types of methods, a setting method and a method of setting the landing point based on the penetration depth from the point of change in the penetration speed of the excavation stirring shaft. Either method is selectively performed according to the ground properties. . The above method is widely applicable not only to the ground configuration where the supporting ground (layer) is clearly present but also to the ground where the N value changes gradually, and there are many applicable grounds. On the other hand, the method is a simplified version of the method,
The present invention is applicable to a ground configuration in which the supporting ground is clearly present and the N value increases rapidly. Usually, as the ground structure, the supporting ground is clearly present, and the ground where the change point of the penetration speed of the excavating and stirring axis clearly appears is occupied most, so the grounding management of most ground improvement by the latter method should be performed. Is possible.

Therefore, as a method of the landing judgment criterion,
It is advisable to consider the above method as a standard and to implement the method according to the configuration of the ground. Next, the above-mentioned two types of landing determination methods will be described below. Method of Determining Based on Penetration Speed of Processing Machine (Excavation Stirring Shaft) and Its Duration Time It is determined that a landing has been made using the landing determination reference diagram as shown in FIG. In the drawing method of the landing determination reference diagram shown in FIG. 3, first, the surface of the support ground is set to the landing determination start depth of 0, and the vertical axis is set to the penetration velocity V and the tip depth d (the depth below the support ground). The horizontal axis represents the time from the landing determination start depth and the cumulative frequency (time) n. In the area A and the area D in the figure, measured values measured every second during the construction of the improved pillar are plotted. The accumulated time of area A is plotted in area B, and the accumulated time of area D is plotted in area C.

The procedure for determining a landing based on the landing determination reference diagram of FIG. 3 is as follows. I) The accumulated time corresponding to the depth of the supporting ground obtained from the curve of the area C in FIG. 3 is obtained. The “accumulated time corresponding to the depth” referred to here is counted from the number of measurements for each depth in order to level out the variation in the measurement result, and this is added from the landing determination start depth (10 m underground in the example of FIG. 3). I do. Since the measurement interval is every second, the result of adding this is the accumulated time. Table 1 shows an example of the relationship between the measurement result and the cumulative time. However, as a method of leveling the dispersion of the measurement results, there is a method of plotting an average value of several measurement values or a method of plotting a median value. For the penetration speed shown in the area A, the accumulated time is calculated similarly to the depth. By the way, in the example of FIG. 3, the depth of the landing management target (10 m underground)
Starting from, the cumulative time to the point P2 where the penetration speed changes suddenly is more than 200 seconds, the cumulative time to the point P1 is 340 seconds, and the cumulative time to the point P0 corresponding to the depth d0 defined as the landing is 460. Seconds and the duration from the point P1 to P0 is 120 seconds. II) Point P where the penetration speed changes greatly in Area B
The accumulated time n2 at 2 is obtained. III) The depth d2 of the point P2 at the accumulated time n2 is obtained using the graph of the area C. This depth d2 is the depth when the excavating blades 2 and 3 at the tip of the excavating and stirring shaft of the processing machine reach the support ground 11, as shown in the situation explanatory diagram a appended to FIG. In the example of FIG. 3, the depth d2 (the depth of the supporting ground) is 11.45 m. IV) In the area B, the accumulated time n1 and the penetration speed V1 at the point P1 at which the penetration speed greatly changes again are obtained. FIG. 3 shows the situation of the tip of the excavation stirring shaft at the point P1
As shown in the situation explanatory diagram b attached therein, the depth is the depth at which the left and right excavating blades 2 and 3 have completely entered the supporting ground 11. V) In the area C, the accumulated time n0 and the penetration speed V1 at the point P0 where the penetration speed greatly changes for the third time are obtained. The situation of the tip of the excavation stirring shaft at the point P0 is, as shown in the situation explanatory diagram c appended in FIG. This is the defined depth d0. In other words, as is clear from the comparison of the situation explanatory diagrams a, b, and c in FIG. 3, the definition of the landing is matched from the depth d2 in the explanatory diagram a in which the left and right excavating blades 2 and 3 reach the support ground 11. The portion up to the depth d0 in the explanatory diagram c is penetrated by the height difference h = 550 mm from the lowermost stirring blade 4. In addition, the penetration speed is v1 = 0.13 m / min from the depth d1 in FIG.
Penetration is performed continuously at 0.1 m / min for 120 seconds. VI) Summing up the above results, the landing judgment by the above method is as follows.

The penetration speed at the start of landing judgment is V1 (0.13 m
/ Min) or less. Duration of penetration speed t = (n0−n1) × β (sec). Here, β is a premium coefficient, and 1.0 is standard. The landing is when the landing determination start penetration speed V1 has continued for t seconds. VII) Investigation example In the bottoming judgment reference diagram in Fig. 3 showing the measurement results from the actual construction results until the bottom of a certain improved column hits the ground, the grounding judgment starting depth (GL-10m) The measurement results up to the bottom are as follows.

1 The landing depth is GL-12.0m,
The geology is a uniform sand layer, and the N value at the bottom is 30 and the N value at the portion to be improved (from the ground surface to the bottom) is 10-20.
2 The landing depth for determining the bottom is GL-10.0 m. 3 The measurement interval is 1 second. 4 The shape of the tip of the excavation stirring shaft of the processing machine used was as shown in FIG. The height difference (clearance) between the tip of the excavating blade and the lowermost stirring blade is 550 mm. Method of setting the penetration depth from the point of change in the penetration speed of the excavating and stirring shaft of the processing machine This method is a simplified method of the above-described method. In this method, as is clear from the P1 and P2 points in the B area in the landing determination reference diagram in FIG. 3 and the situation explanatory diagrams a and b added thereto, the tips of the excavating blades 2 and 3 have large N values. The underground depth d2 of the supporting ground is estimated by using a phenomenon (fact) in which the penetration speed sharply decreases when it comes into contact with the support layer 11. That is, generally, the N
Since the value is larger than the N value of the ground to be improved, the depth d2 of the excavating blade when the penetration speed changes extremely is grasped.
This depth is estimated as the depth of the supporting ground. Therefore, this method is effective when the difference between the N value of the ground to be improved and the N value of the supporting ground 11 is large.

The criterion for the landing determination according to this method is that the lowermost stirring blade 4 of the excavation stirring shaft of the processing machine has a depth h of the height difference h described above than the depth d2 obtained from the landing determination criterion diagram of FIG. When it just penetrates, it is determined that it has landed. In other words, the case where the penetration depth is equal to or greater than 550 mm from the depth d2 at the penetration speed change point P2 is determined as the landing.

[0021]

[Effects of the present invention] According to the deep mixing method with the landing determination method of the present invention, it is possible to accurately determine that the ground has landed on the supporting ground in real time at the stage of each improved column construction. The construction can be performed quickly and with high precision, and an improved pillar or improved ground having a large supporting force can be created.

[Brief description of the drawings]

FIG. 1 is an elevational view of a lower portion of an excavation stirring shaft.

FIG. 2 is a conceptual diagram for defining a landing.

FIG. 3 is an example of creation and determination of a landing determination reference diagram.

FIG. 4 is a sectional view of an example in which the improved ground is used for a permanent foundation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drilling stirring shaft 2 Drilling blade 3 Drilling blade 4 Lowermost stirring blade

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akira Masuda 4-1 Egasakicho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Within the Electric Power Research Laboratory, Tokyo Electric Power Company (72) Inventor Kiyoshi Nakamura 4 Egasakicho, Tsurumi-ku, Yokohama-shi, Kanagawa No. 1 Tokyo Electric Power Company Electric Power Research Laboratory (72) Yoshio Suzuki Inventor Yoshinaka Suzuki Otsuka, Inzai, Chiba Pref. 1-5-1, Takenaka Corporation Technical Research Institute (72) Inventor Yasushi Yazaki 8-21-1, Ginza, Chuo-ku, Tokyo Tokyo, Japan 8-21-1, Takenaka Civil Engineering Co., Ltd. (72) Inventor Akio Shiina 8-21-1, Ginza, Chuo-ku, Tokyo Co., Ltd. The inner (72) inventor Katsumi Higuchi Ginza, Chuo-ku, Tokyo eight-chome No. 21 No. 1 stock company in Takenakadoboku

Claims (5)

[Claims] 1. A deep mixing process for forming an improved column by penetrating a drilling and stirring shaft having a drilling blade and a stirring blade at a tip thereof to a predetermined depth in the ground, and stirring and mixing the excavated in situ soil with a stabilizer. In the construction method, the measured values of the penetration speed of the excavation and stirring shaft, the required time for penetration and the depth of the penetration tip in the construction of the first improved column are collected every unit time until the bottom stage of the excavation and stirring shaft reaches the supporting ground. After that, a graph of the bottoming-out judgment was made, and the construction of the improved pillars thereafter was performed by referring to the above-mentioned bottoming-out judgment, drawing the measured values during construction in real time, and A deep mixing processing method with a bottom determination method, wherein a bottom determination standard diagram is created, and construction is performed while determining the bottom based on the drawing. 2. A deep mixing process in which an excavating agitating shaft provided with excavating blades and agitating blades at its tip penetrates to a predetermined depth in the ground, and stirs and mixes the excavated in situ soil with a stabilizer to form an improved column. In the construction method, the depth of the underground supporting ground at the construction reference point such as survey boring conducted in advance is confirmed in advance based on the soil layer sectional view, and the result of the confirmation is used as preliminary knowledge and the first improvement near the reference point The measured values of the penetration speed of the excavation stirring shaft, the required penetration time, and the depth of the penetration tip in the column construction are measured and collected every unit time until the bottom stirring blade of the excavation stirring shaft reaches the support ground, and the graph is collected. Create a standardized bottoming judgment diagram, and for the subsequent construction of improved columns, refer to the aforementioned bottoming judgment standard diagram, collect each measurement value during construction in real time, and And set the bottom based on the figure. It characterized by construction with a constant, deep Mixing Method accompanied by bottom landing determination method. 3. Confirmation of the depth of the underground supporting ground is performed by previously determining the depth of the supporting ground on which the improved column is to be landed based on the geological survey cross section taken before construction. A deep layer mixing method with the landing determination method according to claim 2. 4. The method according to claim 1, wherein the setting of the landing standard is performed based on the penetration speed of the excavation stirring shaft and the duration thereof in the own landing determination standard diagram created by the improved column construction. Or a deep-layer mixing method with the landing determination method described in 2. 5. The method of setting a landing standard, wherein the setting is based on a penetration depth from a change point of a penetration speed of an excavating agitating shaft in a self-determining landing standard diagram created by improved column construction. A deep mixing method with the landing determination method according to claim 1.