JPH045101B2 - - Google Patents

Description

[Detailed Description of the Invention] (1) Object of the Invention The present invention aims to provide a method for constructing a manhole that can be easily constructed even on soft ground and in a narrow work site. This will be explained in detail below.

(1-A) Regarding conventional technology and problems When constructing a conventional manhole, as shown in Figure 1A, sheet piles 7 are driven in for earth retention and the inside is excavated, but the area is limited to the area required to construct the manhole. It requires considerably more space than the area, and sheet piles 7 are required in narrow places such as urban areas or where there are obstacles such as overhead wires above.
This often causes difficulties in driving and digging operations.

Also, when constructing a manhole, a test excavation is performed, but in the case of soft ground, boiling occurs already during the test excavation, and the surrounding area becomes loose, making excavation difficult. In addition, when constructing manholes, pile driving machines, excavating machines,
A variety of construction machines are required, including special machines for preparing supporting ground, cranes for unloading and assembling manholes, and sheet pile pulling machines, and all of these machines have different base machines, and they also require different types of construction machines, such as special machines for preparing the supporting ground, cranes for unloading and assembling manholes, and sheet pile pullers.
5 also had many problems, such as the large amount of excavated surface and the amount of material required for paving it.

(1-B) Problems to be solved by the present invention In view of the above-mentioned conventional techniques, it is possible to eliminate sheet pile driving during trial excavation and main excavation work, especially in soft ground, and completely prevent the boiling phenomenon. However, we need to provide a manhole construction technology that minimizes the excavation area, allows the same crane to be used for the work, and simply changes the attachment, and can be done efficiently in a short time even in tight spaces. It is something to do.

(2) Regarding the structure and operation of the invention The present invention was invented with the above-mentioned objectives, and the structure and operation thereof will be described in detail below.

When constructing manhole 1, first test excavate the location to check for the presence of underground structures, but if the ground is soft enough that boiling does not occur at the depth of the test excavation, The area has the diameter necessary to erect the upper short pipe 2 with a diameter R' that is several mm larger than the maximum diameter R, and therefore has a diameter only a few mm larger than the diameter R' of the upper short pipe 2 to be erected. (If the road surface is paved, it is sufficient to cut the pavement to the corresponding area.) After confirming the presence of underground structures, remove the upper short pipe 2. will be erected using a small crane. Figure 2 is an explanatory diagram showing the condition of the test excavation.
The depth H of the test pit is usually 1250 mm, and if the boiling phenomenon does not occur at this depth, the upper short pipe 2 is erected using a small crane 9 at this test pit location to ensure that the boiling phenomenon does not occur within the depth of the test pit. If there is a possibility that this may occur, after cutting and removing the pavement, use a small crane 9 to erect the upper short pipe 2 at the relevant location, and gradually erect the upper short pipe 2 while conducting manual excavation (test excavation). Figure 3 shows the upper short pipe 2.
It is an explanatory view showing a state where it is set up.

Next, using the drive motor 16 of the same crane 9, the center shaft 3 is built into the upper short pipe 2 using an earth auger (not shown) at the center of the manhole 1 construction.

In this case, the center position of the manhole construction is the upper short pipe 2.
(See Figure 4.) Next, using this center shaft 3 as a guide, screw anchor 4 is aligned as shown in Figures 5 and 6.
Using the same crane 9, excavate and install to the required depth. The required depth for trench installation is the predetermined depth for manhole installation plus the depth of its foundation. Of course, the depth is sufficient to obtain a force, and therefore the lengths of the anchor shaft 3 and screw anchor 4 should also correspond to this depth.

Next, a lower steel pipe 5 is built inside the upper short pipe 2 and in the soil below it.The diameter R'' of the lower steel pipe 5 is of course set to be larger than the maximum diameter R of the manhole 1. Although it is smaller than the diameter R', the circumferential position 18 (Fig. 7A,
In order to facilitate the erection of the lower steel pipe 5, a moisturizing and water-stopping substance 6 such as a bentonite solution is injected into the soil in B), and as shown in FIG. cylinder pipe 1
0 to the required depth, and inject the moisturizing and water-stopping material 6 through the lower opening/closing valve 17 to form a cylindrical moisturizing and water-stopping material layer 6' (see Figs. 7 and 7). Figure 8) is formed. Of course, the injection is carried out by putting the moisturizing and water-stopping substance 6 into the screw cylinder pipe 10, pushing it into the soil with the piston shaft 19, and then inserting it into the screw cylinder pipe 1.
0 is removed to some extent, and the moisturizing and water-stopping material 6 is injected, and this operation is repeated to form a cylindrical moisturizing and water-stopping material layer 6'. Note that the technique for forming the layer 6' is not limited to the above-mentioned technique, and any injection means may be used.

This moisturizing and water-stopping material layer 6' has the advantageous effect of minimizing the pushing reaction force obtained from the screw anchor 4 and increasing the pushing effect since the soil is soft when the lower steel pipe 5 is inserted. It is something you can have.

Next, the lower steel pipe 5 is erected and inserted into the cylindrical layer 6'.The lower steel pipe 5 is lifted up by the same crane 9, and first placed inside the upper short pipe 2 and placed on the layer 6'. Figure 8).

Next, using the same crane 9, a steel pipe pushing machine 8 is installed on the screw anchor 4, and while receiving a reaction force from the screw anchor 4, the lower steel pipe 5 is pushed into the cylindrical layer 6' to the required depth. (9th
figure). It goes without saying that the technology for installing steel pipes is not limited to the technical means shown in Figure 9 of the drawings.

Further, the lower steel pipe 5 is built in such a way that a part of its upper part overlaps with the upper short pipe 2.
The moisture and water-stopping substance 6 provides good water-stopping around the steel pipe, but if boiling occurs due to lateral pressure in the soil from the gap between these overlapping parts, the steel pipe pushing machine 8 and the screw After the anchor 4 is removed, a bentonite solution or clay is poured into the gap, and measures are taken to prevent this from occurring, such as by inserting and inserting a boiling prevention device 21 containing a fluid or the like in a tube (FIG. 10).

When the erection of the lower lecture pipe 5 is completed, remove the steel pipe pusher 8 and the screw anchor 4, and then use the same crane 9 to remove the earth auger 11.
The soft soil inside the lower steel pipe 5 and below the lower steel pipe 5 is consolidated by making full use of the

For consolidation, mountain sand, dry-mixed concrete, or the like is used as the consolidation material 12 (FIG. 10), but it goes without saying that other consolidation materials may also be used.

In such a case, the support ground 14 for the manhole is constructed, and at the same time, it becomes extremely convenient for the next operation of digging and removing the earth and sand in the manhole installation area using the large-diameter earth auger 13.

Once the construction of the supporting ground 14 for the manhole 1 is completed, use the same crane 9 to install the large-diameter earth auger 13 on the center shaft 3 that was built earlier, instead of the earth auger 11, and use this as a guide. None Earth and sand in the lower steel pipe 5 is removed by moat to the depth of manhole installation. Of course, the large-diameter earth auger 13 is driven by a drive motor 16 attached to the crane 9 (the 11th
figure). After completing the trench removal work, the center shaft 3 is removed. In addition, the supporting ground 14 mentioned earlier
If the strength of the ground is considered insufficient for the installation of manhole 1 during consolidation, the support ground 1 shall be
4, the consolidated material 12 is introduced by the method described above, or the applicant has previously provided the sand pile 22.
40379 by the sand pile construction method, etc. (Fig. 12A), or the 1982-
The foundation of the supporting ground 14 shall be strengthened (prepared) by driving the foundation piles 24 using methods such as 135466, 1983-119734, etc. (Figure 12B).

Next, the manhole 1 is constructed on the supporting ground 14, and the manhole 1 may be a finished product or an assembled type. This is suspended and placed on the supporting ground 14 inside the lower steel pipe 5 using the same crane 9. 26 is millet stone and mortar.

Next, the same crane 9 is used to pull up and remove the upper short pipe 2, and then the lower steel pipe 5 is pulled up to the ground surface, and mortar 15 is poured between the manhole 1 and the lower steel pipe 5 to fill the gap. 5
is lifted and removed by the same crane 9, the road surface is paved 25, and the construction of the manhole is completed. Note that 23 in the drawing is a wire for suspending the lower steel pipe 5.

When constructing the manhole 1, if it is an assembled type, the joints of each part are of course connected with mortar, and the mortar 15 poured between the lower steel pipe 5 and the manhole 1 is used to connect each part. It also acts to strengthen the joints.

(3) Effects of the invention Since the present invention has the structure and function as described above, if the manhole construction site is paved,
When using the conventional construction method, it was necessary to remove several tens of centimeters of pavement outside the sheet piles 7 in order to drive earth retaining piles or sheet piles 7, but in the case of the present invention, in addition to the diameter of the upper short pipe 2, several tens of centimeters of pavement had to be removed outside the sheet piles 7. This has the advantage that only an extra mm of pavement needs to be removed, so that not only little of the bone material is needed to repair the road surface, but also very little time is required for the repair.

When using the conventional construction method, earth retaining piles such as sheet piles (steel sheet piles) must be driven with a pile driving machine, but with the present invention, a pile driver is not required and the upper short pipe can be installed by simply attaching the attachment using the same crane (machine). There is an advantage that it is only necessary to set up and push in 2. Moreover, it is also possible to conduct a test excavation while preventing boiling during the test excavation using the short pipe 2. In this respect, in the case of the conventional method, it is not possible to drive the sheet piles and perform a trial excavation. Underground structures are often damaged during sheet pile driving, and driving requires a large pile driver, and because the sheet piles are tall, there are obstacles such as overhead wires in narrow spaces or in the sky. Sometimes the work is difficult. In this regard, in the case of the present invention, since the height of the upper short pipe 2 is within 1.5 m at most, there is an advantage that the work can be carried out sufficiently with the small crane 9 even in a narrow space or when overhead lines are present in the sky.

In the case of soft ground, when using the conventional method, a fairly long sheet pile must be driven deep into the soil to prevent boiling during work, but when using the present invention, bentonite solution is poured into the soil at the bottom of the inner circumference of the upper short pipe. The lower steel pipe 5 is injected to form a cylindrical moist and watertight layer.
Since the erection is carried out using the same crane, a special base machine is not required for erection, and the erection can be easily carried out, and boiling during earth and sand excavation in the lower steel pipe 5 is completely prevented. is possible. After the construction of the manhole is completed, the soil surrounding the manhole forms a watertight layer, so even a prefabricated manhole has the advantage of not having to worry about water leaking from the joints.

When using conventional methods to excavate earth and sand in manhole construction areas, it is necessary to send a excavator consisting of a special base machine, and in the case of narrow spaces, a special excavator is required. In the case of the invention, a large-diameter earth auger is used with the same small crane (base machine), and the soft soil in the lower steel pipe is compacted, so it is easy to excavate and discharge it. However, there was hardly any excess earth excavated. When using conventional construction methods, it is necessary to excavate and remove an amount of soil that exceeds the volume of the manhole.

When using the conventional construction method, it was necessary to send a special pile driver or ground improvement work machine to prepare the supporting ground for the manhole, but with the present invention, all the work can be done using the same small crane. It has the advantage of being able to move forward.
That is, it can be done in a short time simply by replacing the attachment with the base machine.

When installing the manhole body, if conventional methods were used, it would be necessary to send a crane for unloading and assembly, but now the same small crane can be used to unload and assemble the body by simply replacing the attachments. It can be carried out.

For backfilling work, in the case of conventional construction methods, backfilling earth and sand are brought in using dump trucks, etc., but since the space between the manhole body and the earth retaining pile is wide, a large amount of earth and sand is required, and the soil compaction work and the relevant soil are carried in. Whereas it takes materials and time to pave the area, when using the present invention, a small amount of mortar is filled between the steel pipe and the manhole, so there is only a small amount of earth and sand for backfilling, and there is no need for other materials or work. It has the advantage that it takes very little time.

When using the conventional construction method, it is necessary to send a puller to pull out the earth retaining sheet pile, but the present invention has the advantage that the steel pipe can be immediately pulled out using the same small crane.

[Brief explanation of drawings]

Each of the drawings is an explanatory view showing an embodiment, and FIG. 1A is a plane showing the positional relationship between earth retaining sheet piles and manhole construction by the conventional construction method. FIG. 1B is a plan view showing the construction positional relationship of the upper short pipe 2, the lower steel pipe 5, and the manhole 1 for earth retention according to the present invention. Figure 2A is an explanatory diagram of the case where the manhole construction site is searched and excavated without using the upper short pipe 2.
B is an explanatory diagram when digging is performed while using the upper short pipe 2. FIG. 3 is an explanatory diagram showing the state in which the upper short pipe 2 is erected by a small crane after digging. FIG. 4 is an explanatory diagram showing a state in which the center shaft 3 is installed at the center position of the manhole. FIG. 5 is an explanatory diagram showing how the screw anchor 4 is installed on the center shaft 3. FIG. 6 is an explanatory diagram showing a state in which the screw anchor 4 has been completely installed on the center shaft 3. 7th
Figure A is an explanatory plan view showing the position where bentonite solution is injected to facilitate pushing in the lower steel pipe 5, and Figure B is an explanatory view showing the injection situation. FIG. 8 is an explanatory diagram showing the state in which the lower steel pipe 5 is inserted into the suspended upper short pipe 2 using a small crane 9 in order to erect it, and FIG. It is an explanatory view showing a state in which the lower steel pipe 5 is erected by obtaining a reaction force from. FIG. 10 is an explanatory diagram showing the state of consolidation of the manhole construction part and its supporting ground using the earth auger 11. FIG. 11 is an explanatory view showing the same small crane 9 using the center shaft 3 as a guide and the large-diameter earth auger 13 to excavate and discharge compacted earth and sand from the construction site of the manhole in the lower steel pipe. 1st
2A is an explanatory diagram showing a state in which the manhole supporting ground 14 is reinforced with sand piles 22, and FIG. 2B is an explanatory diagram showing a state in which foundation piles have been driven in with a pile driver. FIG. 13A is an explanatory diagram showing a state in which a manhole is installed on the supporting ground 14, the upper short pipe is removed, the lower steel pipe is pulled up to the ground surface, and mortar is filled between the lower steel pipe and the manhole. FIG. 13B is an explanatory diagram showing the state in which the lower steel pipe is removed;
Figures A, B, and C are explanatory diagrams showing the completion of manhole construction. 1... Manhole, 2... Upper short pipe, 3... Center shaft, 4... Screw anchor, 5
... lower steel pipe, 6 ... moisturizing and water-stopping substance,
6'...Moisturizing and waterproof material layer, 9...Crane, 11...Earth auger, 13...Large diameter earth auger, 14...Supporting ground, 15...Mortar, 16...Drive motor, 18 ... Steel pipe pushing machine, 22 ... Sand pile, 24 ... Foundation pile, 21 ...
Boil prevention device.

Claims (1)

[Claims] 1. An upper short pipe 2 having a diameter R' suitably larger than the maximum diameter R of a manhole 1 to be constructed at a manhole construction site on soft ground is erected using a crane 9, and then the center position of the manhole construction is erected. erect the center shaft 3 using the same crane 9, use the center shaft 3 as a guide to dig and install the screw anchor 4 to the required depth using the same crane 9, and then place it inside the upper short pipe 2. Next, a moisturizing and water-stopping substance 6 such as a bentonite solution is injected into the circumferential position of the lower steel pipe 5 to be erected to the required depth using the screw cylinder pipe 10 using the same crane 9. This constitutes a layer 6' of a moisturizing and water-stopping material. Next, on this moisturizing and water-stopping material layer 6',
The pushing reaction force of the steel pipe pushing machine 8 is obtained from the screw anchor 4, and the lower steel pipe 5 is moved using the same crane 9.
is erected to a predetermined depth, and then the steel pipe pusher 8 and the screw anchor 4 are removed, and then measures to prevent boiling are taken as necessary between the upper short pipe 2 and the lower steel pipe 5 where they partially overlap. 21, the same crane 9 uses the earth auger 11 to inject the soft soil consolidation material 12 into the soft soil inside the lower steel pipe 5 and the lower part of the steel pipe, and the soft soil is consolidated to form the manhole 1.
constitutes the supporting ground. When this support ground construction work is completed, use the same crane to move the earth and sand inside the lower steel pipe 5 to the depth of the manhole installation using the large-diameter earth auger 1 using the center shaft 3 as a guide.
In Step 3, the trench is removed, and if necessary, the foundation for the manhole support ground 14 is further prepared, and then the completed manhole 1 or its assembled parts is lowered onto the support ground 14 inside the lower steel pipe 5 using the same crane 9. Build the manhole 1 and move the upper short pipe 2 with the same crane 9.
The method for constructing a manhole in soft ground is characterized in that the manhole is constructed by pouring mortar 15 between the lower steel pipe 5 and the constructed manhole 1 to fill the gap, and finally pulling out the lower steel pipe 5 to construct the manhole.