JPS62273313A - Composite improving work of soft ground - Google Patents

Abstract

PURPOSE:To completely improve soft ground from deep layer to shallow layer by using a combination of a deep layer compacting work such as vibro-rod construction work, etc., and a shallow layer compacting work by a tamper. CONSTITUTION:A tamper plate 1 is set on a given place, and a deep layer rod 5 is thrust through the hole 4 of the plate 1. The rod 5 is penetrated into a given depth, and while drawing up the rod 5 adequately, the deep layer of the ground is compacted by a vibro-rod construction method. Subsequently, the surface layer of the ground in compacted by operation of the vibrator 2 of the tamper 1. The compaction work can thus be completely performed from the deep layer to the surface layer.

Description

[Detailed description of the invention] 3. Detailed description of the invention b) Purpose of the invention <Industrial application field> The present invention relates to a composite improvement method for soft ground.

<Conventional technology> Conventionally, to improve soft ground, a long hollow pipe for sand pile construction is used, and after penetrating this into the ground, it is pulled out and sand, etc. is discharged from the lower end of the hollow pipe. Deep compaction methods include the so-called sand compaction pile construction method, in which a compacted sand pile is created in the ground by compacting the soil, and the so-called a-tsudofunpection method, in which a long rod is used to vibrate the rod to compact it. There is a construction method.

By the way, with these deep compaction methods, sufficient compaction can be achieved in the presence of confining pressure related to earth pressure in deep areas, but sufficient compaction is difficult in shallow areas because the confining pressure is small. there were. (See Figure 1 fbl) Possible ways to deal with this shallow layer include slowing down the construction speed of the deep layer and increasing the compaction power per unit length.

However, this method has problems in terms of efficiency and economy, such as prolonging the construction time and requiring a large amount of power.

<Problems to be solved by the invention> Therefore, the present invention improves the above-mentioned problems inherent in conventional construction methods, and efficiently and efficiently improves the ground at the required depth, from deep to shallow areas. The purpose of this study is to provide a method for improving soft ground that can be carried out with improved economic efficiency.

(b) Means for solving problems related to structure of the invention> In order to achieve the above object, the present invention has the following structural requirements.

(1) The soil in the ground improvement area is characterized by a combination of deep compaction methods such as pyrolot method and sand compaction pile method, and shallow compaction method using impact force from a damper. Comprehensive improvement method for soft ground.

Fig. 1 (a) (bl and (c)) shows the N value and the N value when the vibro tamper, vibro rod or sand compaction pile (SCP) and the 5 cpt combination of the vibro tamper and vibro rod were installed, respectively. This is a diagram showing the relationship with ground depth, with the N value on the X axis and the y
The depth is plotted on the axis, and in each figure, the N value indicated by a broken line is the N value of the ground before improvement, and the solid line is the N value after improvement. Its (al
Looking at the N line (solid line) after improvement using the vibrodamper, compaction energy does not reach the deep layer (several meters or less).

Its compaction effect does not reach deep layers. On the other hand, its (ti
Pipe 00 Tsudo and SCP have sufficient improvement effects in deep areas (generally, underground depths of several tens of meters to several tens of meters),
In shallow areas, the confining pressure related to earth pressure becomes smaller, so the improvement effect becomes smaller. Therefore, in the improved construction method of the present invention, by combining (al, fb)' mentioned above, they complement each other's shortcomings and efficiently achieve a uniform improvement effect from the shallow layer to the deep layer as shown in fC). This was achieved with economic efficiency in mind.

In addition, among the above construction methods, when using the impact force from a damper, a vibro pile hammer (vibrating pile driver) is generally used as the impact force, but it is also possible to use a diesel pile hammer etc. .

At that time, Fig. 1 fcl shows that a roughly constant compaction strength can be obtained in both the deep and shallow layers, but it may be necessary to increase the strength of the shallow layer to some extent. .

In addition, when performing construction in combination with the above fal and [b],
When combined with sep', the shallow layer may be formed by sand pile (sand pile formed only by pulling out the casing while discharging sand, etc.) or dry pile (by removing the casing without discharging sand, etc.). It is not impossible to implement the construction method of the present invention.

In the above construction method, the number of deep rods (vibro rods) for the damper is not limited to a plurality.

In short, the effect is produced when both methods are used together.

Various types of deep-water rods that have been known in the past can be used for this purpose.
Those described in Japanese Utility Model Publication No. 0, Japanese Utility Model Publication No. 52-38002, or Japanese Utility Model Publication No. 56-55312 can be used.

(1) When using the Piper Rod construction method in combination. Figure 2 1al, (bl and (C)) shows an example of this construction method and the equipment for implementing the same construction method. Figure fal is a front view of the equipment for carrying out the method, in which the damper 1 receives power from a vibrator 2 for tightening as shown in Figure 2 al. Also, a deep rod (vibro rod) 5
The upper ends of the plurality of rods are connected to the vibrator 2' by connecting devices 6, and by this construction, the structure shown in FIG.
Obtain the compaction force with the characteristics shown in bl. Damper vibrator 2
may be suspended from the connector 6 via the shock absorber 3 as shown, or may be separately hung (not shown).

In the figure, the damper plate 1 is provided with a plurality of through holes 4 in the upper and lower directions, and by inserting and assembling the deep rod 5 into each of the through holes 4, the tamper 1 The lifting operation is guided by a rod 5 so that a complex continuity between the deep compaction position and the shallow compaction position is created by itself. In the construction, first, the apparatus is installed at the position where compaction is to be performed, and then the vibrator 2' is operated and the deep layer rod 5 compacts a predetermined deep layer according to the procedure shown in FIG. 2(b) or fe). In this case, generally shallow areas do not require compaction.

Figure 2 1al and (C) show an example of the operation procedure for withdrawing and penetrating the vibrorod, and the time t is plotted on the t'Lx axis and the depth h is plotted on the y axis. The locus of the lower end of the mouth rad is shown as a solid line. Its (bl
'r! For deep areas that require compaction, the rod after penetration is pulled out from the deepest point to the bottom of the surface layer near the ground surface, and then the rod is pulled out again, making the stroke smaller while repeating the operation of re-penetrating the rod even further. It shows the process of compacting the ground at the same time as pulling it out, and it can exert a sufficient compaction effect mutually from the lower layer to the upper layer of the ground.

In the operation shown in (cl), the amount of rod withdrawal is smaller than in the above case, so the compaction effect in the upper layer is smaller than that in the lower layer.

In any case, soil compaction operations using vibrorods or USCPs are not actively performed on the surface layer within the range where the compaction effect of the damper can be achieved. Also, you don't have to do it.

After the compaction operation of the deep layer is completed as described above, the vibrator 2 of the damper 1 is activated, and the surface layer of the ground at the point where the compaction of the deep layer was previously completed is as shown in Figure 1 fal. After compaction, the compaction effect is continuous from the deep layer to the ground surface as shown in Figure 1, and a materially improved ground is obtained.

To achieve the above effect, the vibro damper has a powerful vibrator 2' installed at the top, for example, several tons of vibration force.
On a scale of 100-odd tons, several hundred hertz, virtual amplitude to -
It is desirable to equip equipment with a capacity of 25 liters and a virtual acceleration number of 2 to 1 (liters).In this way, in the deep compaction method, the confining pressure related to the soil is small and a sufficient compaction effect cannot be obtained several meters underground. The compaction of the shallow ground can be completed in one step.

Note that, if necessary, the compaction operation of the shallow layer portion using the damper may be repeated multiple times. When moving the apparatus, it is possible to make the bottom surface of the damper 1 and the lower end of the rod almost at the same height, and in that case, the damper can be moved laterally without lifting it.

(2) (b) Third when using the vibrorod method in combination
The figure shows a front view of another type of device for carrying out the method of the invention, in which the member 1 is suspended by a wire from a connection 6 of a rod 5, which ultimately transfers the weight of the damper to the rod 5. The damper 1 is configured to be lifted and dropped by holding the damper 1. The tamper 1 may be equipped with a vibrator, but the damper must be lifted and dropped using the deep rod 5.
Since this is done after pulling out the damper, a sufficient lifting height of the damper can be obtained, so compaction of the shallow layer by this alone is sufficient to achieve the purpose.

At this time, the deep rod 5 also functions as a guide for the damper 1, and therefore the position where the ground is compacted by both is reliably specified. Moreover, if the deep layer rod is operated while the damper 1 is suspended, the load on the compacted ground increases via the rod 5 by the weight thereof, so that the deep layer compaction effect can be further enhanced.

(3) When using the vibrorod method in combination () → 4th
The figure shows a front view of another type of device, in which:
Reference numeral 7 denotes a hopper provided at the upper part of the damper 1, which is installed for each deep layer rod 5, and is filled with soil improvement material in advance, and when compacting the deep layer of the ground with the deep layer rod 5, the above-mentioned hopper is installed. Material is fed into the lower part of the damper 1 via its through hole 4. With the above-mentioned equipment, sand (improvement material) can be supplied to the compaction section by the rod 5. At that time, if the damper 1 is lifted up to supply sand, the sand can be supplied to the lower part of the damper more effectively. It is possible.

In other respects, this embodiment is the same in operation and effect as the device described in embodiment (1).

(4) (d) Fifth when using the vibrorod method in combination
The figure is a front view of another type of equipment for implementing the construction method of the present invention. In the figure, 8.9 is a joint provided between the deep rod 5 and the damper 1. The space between the two is removably fixed. However, if the joint 9II'i provided on the rod 5 side is installed near the lower end in the longitudinal axis direction and the damper 1 is fixed to the rod, the compaction operation of the deep rod 5 must be completed and the rod pulled out of the compacted ground. It is done in a pulled out state. That is, after compacting the deep layer of the ground with the deep layer rod, the rod and the damper are integrated by operating the joint 8.9, and the energy of the vibrator 2' is applied to the damper 1 via the rod 5. Compact the surface layer of the ground.

In short, since the deep rod and the damper can share the same vibrator, it is possible to omit the vibrator equipped with the damper. The hardened parts can be connected.

(5) (E) No. 6 when using the pipe rod method in combination
The figure shows a front view of another type of equipment for carrying out the composite construction method of the present invention, and this equipment is different from the above-mentioned equipment when a plurality of deep rods 5 are provided. The feature is that each rod is equipped with a vibrator 2.2, and each rod is separate (separated). That is, in Example (1), when a plurality of deep rods 5 are fixed to each other by a single connector 6 as described below, there is an advantage that the vibrator can be shared; If the reaction force is not equal, the connector 6
It takes a lot of effort. In the case of this embodiment, since each deep rod 5 is independent, it is possible to easily compact the ground in response to each reaction force.

(6) When the pipe rod method is used in combination, the deep rod alone is used to compact only the deep layer of the ground, and basically the process shown in Figure 2 fb) or le) is performed. After compaction of the deep layer is completed, there is a construction method in which a separate damper is scanned over the surface layer using each moving means, and the surface layer compaction is repeated. By doing this, it is possible to carry out construction taking into account the entire planned construction area.

(7)? )” Compaction pile method is used in combination.

In this case, the sand compaction pile (SCP) construction method is a method in which a hollow casing with a vibrator attached to the upper end is penetrated into the ground, and a compaction material such as sand, gravel, gravel, etc. is supplied into the casing. In the process of filling and pulling out the casing from the ground, the compaction material is discharged into the ground from the lower end and left behind to create a pile, and is explained in Examples (1) to (6). The SCP method can be used instead of the deep rod compaction process. The essential differences between the above-mentioned method and the deep rod compaction described above are as follows:
The compaction operation of the ground in the deep layer is performed using the compaction material supplied into the casing, and a different material can be used for the shallow layer.

Incidentally, in the case of the SCP using the hollow casing for constructing sand piles or the like in this embodiment, the surface layer portion may be sand drained or may be dry cast.

(c) Effects of the invention As described above, according to the composite improved construction method of the present invention, homogeneous or continuous compaction operations from the deep layer of soft ground to the ground surface can be carried out efficiently and economically. make it possible.

[Brief explanation of drawings]

Figure 2 1al, (bl and tel are diagrams showing the relationship between ground depth and N value when a combination of vibro damper, vibro rod or sep, vibro damper and vibro rod or SCP is installed, respectively. 1al, (b) and fcl indicate examples of the construction method of the present invention and the equipment for carrying out the construction method;
) is a front view of the device, fbl and (C) are examples of operating procedures for pulling out and penetrating deep rods, and Figures 3 to 6 are diagrams of different types of devices for carrying out the method of the present invention. Each front view is shown. l... Damper (tongue half plate), 2.2.2.
... Vibrator, 3.3'... Buffer, 4... Through hole, 5... Deep rod, 6... Connector, 7... Hopper, 8.9...・Joint. Agent Patent Attorney Ei 1) Hiroshi - Figure 3 Figure 5 Figure 6

Claims (1)

[Claims] 1. Soft soil improvement characterized by a combination of deep compaction methods such as the bipro rod method and sand compaction pile method, and shallow compaction methods that utilize the impact force of a damper, on the ground soil in the ground improvement area. Comprehensive ground improvement method.