JPH07224439A - Side lump of manhole - Google Patents

Abstract

PURPOSE:To enhance the safety through increase in the mounting strength of a footing tool, perform location safety when a manhole is assembled, and enhance the working effectiveness. CONSTITUTION:Side lumps 12, 32, 42, 50 of a manhole are configured so that cylindrical wall parts 14, 33, 43, 53 whose tops and bottoms are left open have certain wall thickness W11, W51, and a footing tool 18 is embedded inside of these wall parts 14, 33, 43, 53. As swelling out ring-shapedly upper flanges 15, 44, 55 and lower flanges 16, 45, 56 are formed at the peripheries of the tops and bottoms of the wall parts 14, 33, 43, 53. At the outside surfaces of these wall parts 14, 33, 43, 53, swell-out parts 20, 34, 46, 60 are formed while connections are made between the upper and lower flanges. When side lumps 12, 32, 42, 50 are molded, the embedded side end part 18C of the footing tool 18 is extended outward from the wall parts 14, 33, 43, 53 and embedded in the swellout parts 20, 34, 46, 60.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a side block of a manhole used for sewers and the like.

[0002]

2. Description of the Related Art Conventionally, a side mass of a manhole used for sewerage and the like and in which a person enters and leaves is constructed by assembling a large number of hollow cylindrical straight walls 2 as shown in FIGS.
As shown in FIG. 11, the straight wall 2 made of concrete includes a cylindrical wall portion 4, an upper collar portion 5 and a lower collar portion 6 which are formed in an annular shape by bulging to the outer peripheral sides of the upper and lower ends of the wall portion 4, respectively. Is integrally formed by a mold. During molding of the straight wall 2, reinforcing bars 7 are provided inside the wall portion 4, the upper collar portion 5 and the lower collar portion 6.
Is embedded in a predetermined number according to the standard, and the wall 4
On the inner side of the, footrests 8 are provided vertically with a predetermined interval. The straight wall 2 has a predetermined inner diameter R1, wall thickness W1, and height H1 that are determined according to the standard (for example, J
R1 = 900mm, W1 = 60mm, H1 according to IS standard
= 600 mm). The upper flange portion 5 and the lower collar portion 6 each have a flat end surface on the opening side, and have a predetermined radial width W2 (for example, W2 = 150 mm) and a predetermined height H2 (H2) depending on the inner diameter R1 of the wall portion 4. = 50 mm).

As shown in FIG. 12, the footrest 8 is formed by bending a round bar-shaped metal fitting into a U-shape. Foot hanger 8
The footrest portion 8A and a pair of support portions 8B extending from both ends of the footrest portion 8A. The footrest 8A has an anti-slip groove 9 engraved on a flat upper surface. The sizes of the footrest portion 8A and the support portion 8B are determined according to the standard. For example, in the 40 SW type of the footrest 8, the length of the footrest 8A and the length of the support 8B are 400 mm and 250 mm, respectively, and the diameter is 22 mm. When the straight wall 2 is molded, the foot hanger 8 has a leg hanger 8A that horizontally extends toward the center of the straight wall 2 by a predetermined dimension S1 (for example, S1 = 16).
0 mm) and the supporting portion 8B penetrates the space between the reinforcing bars 7 and the wall portion 4
It is housed inside and buried. In the size of the foot hanger 8 according to this standard, when the support end 8C of the foot hanger 8 is embedded in the wall portion 4 (W1 = 60 mm), the foot hanger portion 8A projects beyond the predetermined dimension S1 toward the center of the straight wall 2. ,
Installation strength cannot be secured. On the other hand, when the footrest 8A is projected toward the center of the straight wall 2 by a predetermined dimension S1 and is to be embedded, the terminal end 8 of the support 8B.
C projects outward from the wall portion 4. Therefore, in the conventional side block, the end portion 8C of the support portion 8B is cut in advance,
The footrest 8 is embedded so that the cut end portion 8D fits inside the wall portion 4. However, as the depth of the manhole becomes deeper, strength is required for attaching the footrest 8 in consideration of safety. However, in the leg hanger 8 with the support portion 8A cut, the joint area with the concrete in the wall portion 4 is limited, so there is concern about the strength.
For this reason, when the strength of the leg hanger 8 is required, reinforcing metal fittings are respectively welded to the precut end portions 8D,
When the footrest fitting 8 is buried during molding, the joint surface with concrete is increased.

At the time of assembling the side mass of the manhole, the molded straight walls 2 are hung one by one in the holes of the ground excavated for the manhole by a crane to position the straight walls 2 in the circumferential direction, and the foot hanger 8 Assemble so that they line up in the vertical direction. Since the positioning of the straight wall 2 must be performed while checking the leg hanger 8 in the straight wall 2, an operator enters the straight wall 2 and positions it visually. The above process was repeated and the straight walls 2 were stacked one by one to assemble side blocks.

[0005]

In the above-mentioned conventional manhole side block, in order to improve the attachment strength of the foot hanger 8, when the supporting portion 8B of the foot hanger 8 manufactured according to the standard is cut and used, There is a problem that it takes time and effort to weld the auxiliary metal fittings. Moreover, the auxiliary metal member to be welded is required to have a shape that does not impair the strength of the concrete of the wall portion 4 by thinning it. On the other hand, the foot hanger 8 itself satisfies the strength or safety standard according to the standard as long as the support portion 8A is embedded in the concrete of a predetermined size, and therefore is manufactured according to the standard for the purpose of improving the mounting strength. If the attached leg hanger 8 is attached, there is a problem that the wall portion as a whole must be made thicker, resulting in an increase in cost and a reduction in work efficiency.

In the conventional manhole side block, when the cylindrical straight wall 2 is positioned, a worker enters the straight wall 2 and
Positioning is performed while confirming the position of the leg hanger 8 in the straight wall 2, and the side blocks are assembled by stacking them one by one, which is not preferable for safety, and there is a problem that the positioning operation takes time.

The present invention has been made to eliminate the above drawbacks, and an object of the present invention is to provide a side block of a manhole with improved mounting strength of a footrest and high safety. Further, it is another object of the present invention to provide a side mass of a manhole, which can be positioned from the outside when assembling the manhole, can perform work safely, and can improve work efficiency.

[0008]

A side wall of a manhole according to the present invention comprises a tubular wall portion having upper and lower openings, a predetermined wall thickness, and a footrest embedded therein, and a tubular wall portion of the tubular wall portion. A side mass of a manhole molded with upper and lower collars formed by bulging in an annular shape on the outer circumference of the upper and lower ends, respectively, and forming a bulge on the outer surface of the cylindrical wall portion, the footrest The embedding side end portion of the tool is extended outward from the tubular wall portion, embedded in the bulging portion, and molded.

[0009]

In the side mass of the manhole according to the present invention, since the bulging portion is formed on the outer surface of the tubular wall portion on the side of the foot hanger, when the side mass is molded, the embedded side end of the foot hanger has the cylindrical wall portion. Even if it projects further outward, the projecting end of the foot hanger can be embedded and molded in the bulging portion, and the foot hanger can be attached while ensuring the strength satisfying the standard. Further, since the bulging portion is formed on the outer peripheral surface of the wall portion in accordance with the position of the footrest, it is possible to perform positioning from the outside when assembling the side mass.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. 1 is a plan view showing a straight wall forming a side block of a manhole according to an embodiment of the present invention, FIG. 2 is a vertical sectional view taken along line II-II of FIG. 1, and FIG. 4 is a vertical sectional view showing a modified example of the wall, FIGS. 4 to 5 are plan views showing the footrest, and VV line sectional views are shown in FIGS. 6 to 7, respectively.
FIG. 8 is a plan view and a front view showing a modification of the straight wall shown in FIG. 8, FIG. 8 is a plan view showing a sloping wall forming a side block of a manhole according to another embodiment of the present invention, and FIG. FIG. 10 is a longitudinal sectional view taken along the line IX, and FIG. 10 is an explanatory view showing the assembled state of the side block according to the present invention.

The side block of the manhole is formed by stacking a large number of straight walls as shown in FIG. 1 on the uppermost part of the stacked straight walls.
It is configured by mounting a sloping wall on the inlet side as shown in (see FIG. 10). First, the straight wall 12 shown in FIG. 1 will be described. The straight wall 12 is molded by pouring concrete into a mold (not shown). Straight wall 12 with a hollow interior
Is a cylindrical wall 14 as shown in FIGS.
And an upper flange portion 15 and a lower flange portion 16 which are formed to bulge in an annular shape on the outer peripheral sides of the upper and lower ends of the wall portion 14, respectively. During molding of the straight wall 12, as shown in FIG. 2, reinforcing bars 17 for reinforcement are embedded in the wall portion 14, the upper flange portion 15 and the lower flange portion 16 according to the standard, and On the inside of the portion 14, a foot hanger 18 is provided at predetermined vertical positions from the upper and lower ends (from the upper and lower ends to the foot hanger 18
In the present embodiment, D1 = D2 = 150 mm, where D1 and D2 are the distances to the respective points. Each leg hanger 18 is provided vertically with a predetermined distance D3 (D3 = D1 + D2 = 300 mm). The straight wall 12 has a predetermined inner diameter R according to the standard.
11, wall thickness W11, and height H11 are determined (for example, in this embodiment, R11 = 900 m according to JIS standard).
m, W11 = 60 mm, H11 = 600 mm). Upper collar part 15
And the lower flange portion 16 have the same outer diameter, the upper and lower end surfaces 15A and 16A are formed flat, and a predetermined radial width W12 (W12 = 15) according to the inner diameter R11 of the wall portion 14.
0 mm) and a predetermined height H12 (H12 = 50 mm). Outer peripheral surfaces 15B of the upper and lower collar portions 15 and 16 are 1
6B is a predetermined angle α (α = α) with the outer peripheral surface 14A of the wall portion 14.
They are connected at an angle of 120 °).

As shown in FIGS. 4 and 5, the footrest 18 is formed by bending a round bar-shaped metal fitting into a U-shape, and has a footrest 18A and a pair of legs extending from both ends of the footrest 18A. It is composed of a support portion 18B. A cover 19 having an anti-slip groove formed on its upper surface is attached to the footrest portion 18A. The tip 18C of each support 18B is bent upward. The sizes of the footrest portion 18A and the support portion 18B are determined according to the standard. In this embodiment, the leg hanger 18 is a JIS standard 40SW type, and has a metal fitting diameter R.
12, the length L1l of the footrest 18A and the support 18B
Has a predetermined horizontal length L12 (for example, in this embodiment, R12 = 22 mm according to JIS standard,
L11 = 400 mm, L12 = 250 mm). Foot rest 18
When molding the straight wall 2, as shown in FIG.
A is a predetermined dimension S2 horizontally toward the center of the straight wall 12.
(For example, S2 = 160 mm) is projected and embedded. The footrest 18 conforming to this JIS standard has a buried portion E (60 mm <E <(L12-S
When 2) mm) is embedded in a concrete wall, it meets the specified mounting strength and safety standards.

By the way, on the outer peripheral surface 14A of the wall portion 14,
As shown in FIGS. 1 and 2, the bulging portion 20 is formed. The leg hanger 18 is the wall portion 1 corresponding to the region of the bulging portion 20.
4 is provided inside. Bulge 20
Is a predetermined dimension (an arc formed by the outer peripheral surface 20A of the bulging portion 20) C that connects the upper collar portion 15 and the lower collar portion 16 and is arranged in the circumferential direction.
Have one. The outer peripheral surface 20A of the bulging portion 20 is the upper collar portion 1
5 and the outer peripheral surfaces 15B, 16B of the lower collar portion 16 and the outer peripheral surface 14A of the wall portion 14 and the inclined surface 20.
Connected by B. In the bulging portion 20, if the length of a line segment connecting both ends of the arc C1 of the outer peripheral surface 20A is W13, the length W13 of the line segment is the distance between the both end portions 18C, 18C of the support portion 18B (of the footrest portion 18A). The predetermined dimension C1 in the circumferential direction is determined to be longer than the length L11. Bulge 2
0 is the wall portion 14 and the upper and lower collar portions 1 when the straight wall 12 is molded.
5, 16 are integrally molded with a mold frame (not shown), and when the footrest 18 is attached to a predetermined position inside the wall portion 14, both end portions 18C, 18C of the support portion 18B are internally provided.
Is to be paid. Therefore, the footrest 18
The embedded portion E of the support portion 18B is embedded in the concrete defined by the wall portion 14 and the bulging portion 20 and attached to the straight wall 12.

Next, the operation of the side mass of the manhole according to the above embodiment will be described. When the straight wall 12 is cast by pouring concrete into the formwork, the wall portion 14, the upper and lower brim portions 15, 16, the reinforcing bar 17 and the bulging portion 20 are integrally molded, and the leg hanger 18 is the wall portion. It is attached at a predetermined position inside 14. In the footrest 18, the footrest 18A horizontally projects toward the center of the straight wall 12 by a predetermined dimension S2, the support 18B penetrates the space between the rebars 17 and penetrates the wall 14, and both ends 18C of the support 18B. , 18C is the bulge 2
0, and the embedded portion E of the support portion 18B is embedded in concrete from the wall portion 14 to the bulging portion 20.
Therefore, the leg hanger 18 can ensure the strength satisfying the standard.

In addition, when the side mass of the manhole according to the above-mentioned embodiment is assembled, the molded straight walls 12 are hung one by one into the holes of the ground excavated for the manhole by a crane. At this time, the upper straight wall 12 is hung on the lower straight wall 12, and the bulging portion 2 of the upper straight wall 12 is visually observable from the outside of the straight wall 12 to the bulging portion 2 of the lower straight wall 12.
When 0 is matched and positioning is performed in the circumferential direction, the footrest 8
Are aligned vertically. For this reason, the positioning can be visually performed from the outside even if the worker does not enter the straight wall 2. By repeating the above steps, the straight walls 2 are stacked one by one to assemble a side block, and backfilling is performed in the gap between the ground and the side block to complete the manhole assembly.

FIG. 3 shows a modification of the straight wall 12 constituting the side block of the manhole according to the above embodiment, and the same reference numerals as those in the above embodiment indicate the same or corresponding portions. As shown in FIG. 3, the straight wall 32 has a height H31 (H
31 = 300 mm), the leg hanger 18 is a straight wall 32
A predetermined position from the upper and lower ends (distance D1 = D2 from the upper and lower ends)
(= 150 mm), it has almost the same configuration except that it is provided in one place. That is, in the straight wall 32, the bulging portion 34 is formed on the outer peripheral surface 33A of the cylindrical wall portion 33. This bulge 3
The foot hanger 18 is provided inside the wall portion 33 corresponding to the portion of No. 2. The bulging portion 34 connects the upper flange portion 15 and the lower flange portion 16 and has a predetermined dimension (not shown) along the circumferential direction. The outer peripheral surface 34A of the bulging portion 34 is formed so as to coincide with the upper and lower outer peripheral surfaces 15B and 16B of the flange portions, and is connected to the outer peripheral surface 33A of the wall portion 33 by the inclined surface 34B. Bulge 34
Is the length of the line segment connecting the arcuate ends of the outer peripheral surface 34A to W13.
Then, the length W13 of the line segment is the distance L1 between the both end portions 18C and 18C of the support portion 18B (the length of the footrest portion 18A) L1.
The predetermined dimension in the circumferential direction is determined so as to be longer than 1. Similar to the above-described embodiment, the bulging portion 34 is adapted to house both end portions 18C and 18C of the support portion 18B when the straight wall 32 is molded. Therefore, the footrest 18 is attached to the straight wall 32 with the embedded portion E of the support portion 18B embedded in concrete. Therefore, the footrest 18 is
It can be attached to the straight wall 32 while ensuring the strength satisfying the standard, and can be positioned from the outside by the bulging portion 34 during side block assembly.

6 and 7 show a modified example of the straight wall 12 which constitutes the side mass of the manhole according to the above embodiment, and the straight wall 42 is a cylindrical wall as shown in FIG. Part 4
3 is formed in an elliptical shape. Upper collar portion 44 and lower collar portion 45
Have the same outer circumference above and below the cylindrical wall portion 43, and bulge outward over the entire circumference. The bulging portion 46 is the upper collar portion 44.
Is formed so as to be connected to the lower collar portion 45 and to match the outer peripheral surfaces 44A and 45A of the upper collar portion 44 and the lower collar portion 45.
The support portion 18B of the footrest 18 is embedded in the interior of the footrest 6. Therefore, the leg hanger 18 can be attached to the straight wall 42 while ensuring the strength satisfying the standard.

Next, a side block of a manhole according to another embodiment of the present invention will be described with reference to FIGS. 8 and 9. The same reference numerals as those used in the above-described embodiments and modifications indicate the same or corresponding parts. The sloping wall 50 forming the side block of the manhole includes a straight wall-shaped wall portion 52 in which a cylindrical wall portion 51 rises vertically, and a slanted wall that is continuous with the straight wall-shaped portion 52 and expands downward. It is composed of a wall-shaped portion 53. The sloping wall 50 is formed by bulging annularly an upper collar portion 55 and a lower collar portion 56 on the outer peripheral side of the upper and lower ends of the wall portion 51. A predetermined number of reinforcing bars 57 are embedded in the wall portion 51, the upper flange portion 55, and the lower flange portion 56 of the one-sided inclined wall 50 according to the standard. Inside the wall portion 51 on the side of the straight wall-shaped wall portion 52, the foot hanger 18 is provided at a predetermined position from the upper and lower ends (the distances from the upper and lower ends to the foot hanger 18 are D1 and D, respectively).
2) Each leg hanger 18 has a predetermined distance D3 (D3 = D1).
+ D2) are provided separately. For the sloping wall 50, an upper opening side inner diameter R51, a lower opening side inner diameter R52, a wall thickness W51, and a height H51 are determined according to the standard (for example, in the present embodiment, R51 = 600 mm according to the JIS standard, R52 =
900mm, W51 = 60mm, H51 = 600mm). The upper collar portion 55 and the lower collar portion 56 are formed with different outer diameters R55 and R56, respectively (in this embodiment, R55 = 110).
0 mm, R56 = 1200 mm). Upper collar portion 55 and lower collar portion 56
Have upper and lower end surfaces 55A and 56A formed flat and have predetermined radial widths W52 and W53 (W52 = 250 m).
m, W53 = 150 mm) and a predetermined height H in the vertical direction
52 and H53 (H52 = 60 mm, H53 = 50 mm). Therefore, the straight wall-shaped wall portion 52 side of the upper collar portion 55 projects outward from the lower lower collar portion 56. Upper collar part 55
And outer peripheral surfaces 55B and 56B of the lower collar portion 56 are connected to the outer peripheral surface 51A of the wall portion 51 at an angle.

By the way, on the outer peripheral surface 51A of the wall portion 51,
As shown in FIGS. 8 and 9, the bulging portion 60 is formed. The leg hanger 18 corresponds to the portion of the bulging portion 60 and is attached to the wall portion 5
It is designed to be provided inside 1. Bulge 60
Is formed so as to rise from the lower flange portion 56 side of the straight wall-shaped wall portion 52 and to coincide with the outer peripheral surface 56B of the lower flange portion 56, connect the upper flange portion 56 and the lower flange portion 56, and Has a predetermined dimension C2 (C2 is an arc formed by the outer peripheral surface 60A of the bulging portion 60). The bulging portion 60 is connected to the outer peripheral surface 51A of the wall portion 51 by the inclined surface 60B. Bulge 60
As shown in FIG. 8, assuming that the length of a line segment connecting both ends of the arc C2 of the outer peripheral surface 60A is W13, the length W13 of the line segment is
However, the predetermined circumferential dimension C2 is determined so as to be longer than the distance (length of the footrest portion 18A) L11 between the both end portions 18C and 18C of the support portion 18B. The bulging portion 60 is provided with the wall portion 51 and the upper and lower flange portions 55 and 56 when the unilateral wall 50 is molded.
At the same time, it is integrally molded by a mold (not shown) so that both ends 18C, 18C of the support 18B can be housed inside when the footrest 18 is attached to a predetermined position of the wall 51. Therefore, the leg hanger 18 has a support portion 18B.
The embedded portion E is embedded in the concrete defined by the wall portion 51 and the bulging portion 60 and attached to the sloping wall 50. The footrest 18 is used when the sloping wall 50 is molded.
8A has a predetermined dimension S horizontally toward the center of the sloping wall 50.
2 (for example, S2 = 160 mm) is projected and embedded, and the embedded portion E (60 mm <E
When <(L12-S2) mm) is embedded in the concrete wall, it meets the predetermined mounting strength and safety standards.

Next, the operation of the side mass of the manhole according to the above embodiment will be described. When the concrete is poured into the formwork to form the sloping wall 50, the wall portion 51, the upper and lower flange portions 55 and 56, the reinforcing bar 57, and the bulging portion 60 are integrally formed, and the leg hanger 18 is attached to the wall. It is attached at a predetermined position inside the portion 51. The foot rest 18 is a foot rest 18A.
While protruding horizontally toward the center side of the sloping wall 50 by a predetermined dimension S2, the supporting portion 18B penetrates the wall portion 51 through the space between the reinforcing bars 57, and both end portions 18C, 18 of the supporting portion 18B.
C is housed in the bulging portion 60, and the embedded portion E of the support portion 18B
Is embedded in the concrete from the wall portion 51 to the bulging portion 60. Therefore, the leg hanger 18 can ensure the strength satisfying the standard.

In the side mass of the manhole according to each of the above embodiments and modifications, the bulging portion is formed by connecting the upper flange portion and the lower collar portion, but the invention is not limited to this. It is needless to say that the projecting portion is limited to the vicinity of the portion where the supporting portion 18B of the footrest 18 projects and is divided and formed within a range in which a predetermined strength can be secured to reduce the weight.

[0022]

As described above, according to the present invention, the bulging portion is formed on the outer surface of the tubular wall portion, and the embedded side end portion of the foot hanger is extended outward from the tubular wall portion. By embedding and molding in the bulging portion, the attachment strength of the foot hanger can be improved, and therefore the safety of maintenance work can be improved. Further, according to the present invention, since the positioning at the time of assembling the manhole can be easily performed from the outside, the assembling work can be performed safely, and the work efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a plan view showing a straight wall forming a side block of a manhole according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view taken along line II-II of the straight wall in FIG.

FIG. 3 is a vertical cross-sectional view showing a modification of the straight wall of FIG.

FIG. 4 is a plan view showing a footrest.

5 is a sectional view taken along line VV of the footrest of FIG.

FIG. 6 is a plan view showing a modified example of a straight wall.

FIG. 7 is a front view of the straight wall of FIG.

FIG. 8 is a plan view showing a sloping wall forming a side block of a manhole according to another embodiment of the present invention.

9 is a vertical sectional view taken along line IX-IX of the sloping wall in FIG.

FIG. 10 is an explanatory diagram showing an assembled state of a side block of a manhole according to the present invention.

FIG. 11 is a vertical cross-sectional view showing a conventional straight wall.

FIG. 12 is a plan view showing a conventional straight wall.

[Explanation of symbols]

 12, 32, 42 Straight wall (side mass) 14, 33, 43, 53 Cylindrical wall portion 15, 44, 55 Upper collar portion 16, 45, 56 Lower collar portion 18 Foot fitting 18C Embedded side end portion of foot fitting 20 , 34, 46, 60 Bulging part 50 Uni-sloping wall (side mass) W11, W51 Wall thickness

Claims (7)

[Claims] 1. A cylindrical wall portion which is opened at the upper and lower sides and has a predetermined wall thickness and in which footrests are embedded, and a cylindrical wall portion which is bulged in an annular shape on the outer peripheral side of the upper and lower ends of the cylindrical wall portion. In a side mass of a manhole molded with upper and lower flanges, a bulge portion is formed on the outer surface of the tubular wall portion, and the embedded side end of the leg hanger is outward from the tubular wall portion. A side mass of a manhole, which is formed by extending and embedding it in the bulging portion. 2. The side block of the manhole according to claim 1, wherein the bulging portion is formed by connecting the upper flange portion and the lower collar portion. 3. The side block of the manhole according to claim 1, wherein the side wall has a cylindrical wall portion having a straight wall with a circular cross section. 4. The side block of a manhole according to claim 1, wherein the side wall has a cylindrical wall portion having a straight wall with an elliptical cross section. 5. The upper collar portion and the lower collar portion have the same outer diameter, and the bulging portion is formed so as to coincide with the outer peripheral surfaces of the upper collar portion and the lower collar portion. The side mass of the manhole according to Item 3 or 4. 6. The side mass is a unilateral wall having a straight wall-shaped portion in which a tubular wall portion stands upright and a sloping wall-shaped portion whose diameter increases as it goes downward. Side mass of the manhole described in 2. 7. The upper collar portion projects outwardly from the lower collar portion, and the bulging portion rises from the lower collar portion on the straight wall-shaped portion of the sloping wall and conforms to the outer peripheral surface of the lower collar portion. The side mass of the manhole according to claim 6, which is formed.