JP2017150150A - Lid for underground structure and set of lid and receiving frame for underground structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lid for underground structure and a set of lid and receiving frame for underground structure which can release inner pressure efficiently by securing a discharge of fluid so as to suppress dispersion of a lid for underground structure.SOLUTION: A lid for underground structure comprises a top face 21a on the ground side that closes an opening H communicating with an underground structure and a side face 22 having a fitting part 221a fitted to an inner peripheral surface 31 of a receiving frame 3 buried with the upper end face 32 exposed to the ground. The side face 22 has a closed upper part and the side face is provided with an inner pressure release port 7a opening to the inner peripheral surface 31 when the fitting part 221a is fitted to the inner peripheral surface 31 of the receiving frame 3.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an underground structure lid that closes an opening connected to an underground structure, and an underground structure lid receiving frame set including the underground structure lid and a receiving frame.

  In places where underground structures such as sewers and waterworks or underground structures such as electric power, gas, and communication are connected to the ground, a receiving frame that defines an opening that connects to the underground structure, and a state in which the receiving frame is fitted In some cases, an underground structure lid receiving frame set including an underground structure lid that closes the opening is installed.

  Here, when the underground structure is sewerage, if water exceeding the flow capacity flows into the sewer pipe due to torrential rain or tsunami backflow into the sewer, the air pressure and water pressure (internal pressure) in the manhole suddenly increases. It has been pointed out that there is a case where the cover for the underground structure may fly up. In particular, as a social environment, there is a tendency to easily disengage the receiving frame and the cover for the underground structure in order to avoid damage to the structure in the event of an abnormality, and measures to prevent scattering of the cover for the underground structure Is strongly demanded. Therefore, we have devised measures to release the manhole internal pressure, and there is an underground structure lid receiving frame set that tries to prevent the underground structure lid from scattering even if a large amount of water flows into the sewer pipe due to heavy rain. It has been proposed (see, for example, Patent Document 1 and Patent Document 2).

  In these underground structure lid receiving frame sets described in Patent Literature 1 and Patent Literature 2, the underground structure lid has a fitting surface that is inclined inward as it goes downward on its side surface, and an engagement protrusion. I have. Further, when the receiving frame is inclined inwardly toward the inner peripheral surface thereof and the fitting surface of the cover for the underground structure is fitted, and the cover for the underground structure floats to a predetermined height, the underground structure And an engagement recess with which the engagement protrusion of the object lid is engaged. In the manhole where these underground structure lid receiving frame sets are installed, the internal pressure rises, and when this increased internal pressure exceeds the pressure required for the underground structure lid to rise, the underground structure lid rises and the underground structure The engagement protrusion of the lid is engaged with the engagement recess of the inner frame. In the state where the lid for the underground structure is lifted, a gap is formed between the fitting surface of the lid for the underground structure and the taper portion of the receiving frame, so fluid (gas or liquid) is discharged upward from this gap. To release internal pressure. Although there may be problems due to the floating of the underground structure lid, it is compared with the danger when the underground structure lid is scattered, and here, the floating height of the underground structure lid is suppressed as much as possible. However, it adopts the concept of allowing the underground structure lid to float to some extent.

JP 2001-26938 A JP 2003-328379 A

  However, in the underground structure lid receiving frame set described in Patent Document 1 and Patent Document 2, if the floating height of the underground structure lid is suppressed, the fitting surface of the underground structure lid and the taper of the receiving frame are used. It is difficult to ensure a sufficient gap between the parts. For this reason, the fluid is insufficiently discharged, and as a result, the internal pressure cannot be sufficiently released and the scattering of the underground structure lid may not be prevented. Further, in the underground structure lid receiving frame set described in Patent Literature 1 and Patent Literature 2, there is a possibility that scattering of the underground structure lid may be promoted by the fluid discharged upward.

  In view of the above circumstances, the present invention provides an underground structure lid and an underground structure lid receiving frame that can efficiently release internal pressure by suppressing a fluid discharge amount and suppress scattering of the underground structure lid. The purpose is to provide a set.

The lid for an underground structure of the present invention that solves the above-mentioned object closes an opening that leads to the underground structure, and an upper surface that becomes the ground side,
A side surface provided with a fitting portion that fits to the inner peripheral surface of the receiving frame embedded with the upper end surface exposed to the ground,
The side surface is provided with an internal pressure release port that opens toward the inner peripheral surface when the upper portion is closed and the fitting portion is engaged with the inner peripheral surface of the receiving frame. To do.

  Here, the side surface may have an extending portion extending downward from the fitting portion, and the internal pressure release port may be provided in the extending portion. It may be provided in the fitting portion, or may be provided from the extending portion to the fitting portion. The internal pressure release port may be opened obliquely upward. Further, the receiving frame may be cylindrical.

  According to the lid for an underground structure of the present invention, since the fitting portion includes the internal pressure release port that opens toward the inner peripheral surface when the fitting portion is fitted to the inner peripheral surface of the receiving frame, With the structure lid floating, the fluid can be discharged from the internal pressure release port, for example, toward the side. Thus, even when the flying height of the lid for the underground structure is suppressed, compared to the conventional mode in which the fluid flows out from the gap between the fitting surface of the lid for the underground structure and the tapered portion of the receiving frame, The amount of discharge is secured, and the internal pressure can be released efficiently. As a result, scattering of the underground structure lid can be suppressed. Further, since the internal pressure release port that opens toward the inner peripheral surface is provided, the fluid discharged from the internal pressure release port is difficult to move upward. For this reason, there is little possibility of promoting the scattering of the lid for the underground structure.

  In the underground structure lid according to the present invention, the internal pressure release port may have a lower end of the side face cut out.

  Furthermore, in the lid for an underground structure according to the present invention, the internal pressure release port may be provided at a point-symmetrical position on the side surface with respect to a center point of the lid for the underground structure.

  In other words, the internal pressure release ports are provided at positions that face each other by 180 degrees. In addition, a plurality of the internal pressure release ports are provided at intervals in the circumferential direction of the side surface. Among the plurality of internal pressure release ports, internal pressure release ports arranged so that the intervals are equal are provided. It may be included.

  According to the aspect in which the internal pressure release port is provided at a point-symmetrical position with respect to the center point of the underground structure lid on the side surface, the internal pressure release port floats by discharging the fluid from each internal pressure release port. The tilt of the lid for underground structures is suppressed. As a result, it is possible to avoid a problem that the floating underground structure lid is inclined to make it difficult to discharge the fluid from some internal pressure release ports.

  Further, the underground structure lid of the present invention may be provided with a release channel formed between a pair of ribs protruding downward and connected to the internal pressure release port.

  Here, the release channel may be a groove or a hole.

  By providing the release channel, the fluid can be efficiently discharged from the release channel.

The lid receiving frame set for an underground structure of the present invention that solves the above-mentioned object is a receiving frame that is embedded with the upper end surface exposed to the ground,
A cover for an underground structure having a side surface provided with a fitting portion to be fitted to the inner peripheral surface of the receiving frame;
The side of the lid for the underground structure is provided with an internal pressure release port that is closed at the top and opens toward the inner peripheral surface when the fitting portion is fitted to the inner peripheral surface of the receiving frame. It is characterized by being.

Here, the inner peripheral surface of the receiving frame has a tapered portion inclined inward as it goes downward, and an extending portion that continues downward from the tapered portion,
In the state where the fitting portion is fitted to the inner peripheral surface of the receiving frame, the internal pressure release port may open toward the extending portion, or open toward the tapered portion. It may be, and it may be opened from the extension part to the taper part.

  According to the underground structure lid receiving frame set of the present invention, the fluid can be efficiently discharged, and there is little possibility that the fluid discharged from the internal pressure release port promotes the scattering of the underground structure lid. .

  According to the present invention, there is provided an underground structure lid and an underground structure lid receiving frame set capable of efficiently releasing internal pressure by securing a fluid discharge amount and suppressing scattering of the underground structure lid. Can be provided.

(A) is sectional drawing of the lid receiving frame set for underground structures which is one Embodiment of this invention, (b) is a top view of the lid receiving frame set for underground structures shown to (a). It is a rear view of the manhole cover shown in FIG.1 (b). It is a figure which shows a mode that the internal pressure of a manhole rose and the manhole cover shown to Fig.1 (a) floated. (A) is a BB line sectional view of Drawing 1 (b), and (b) shows signs that the internal pressure of a manhole rose and the manhole cover shown in (a) floated to the limit levitation position. FIG. (A) is CC sectional view taken on the line of FIG.1 (b), (b) is an enlarged view which expands and shows the D section of (a), (c) is (b). It is a figure which shows a mode that the manhole cover shown similarly floated to the limit levitation position. It is the figure which looked at the side of the manhole cover from the front of the internal pressure release port. It is the EE sectional view taken on the line of FIG.1 (b). (A) shows a first modification of the lid receiving frame set, and (b) shows a second modification of the lid receiving frame set.

  Embodiments of the present invention will be described below with reference to the drawings.

  Fig.1 (a) is sectional drawing of the lid receiving frame set for underground structures which is one Embodiment of this invention, FIG.1 (b) is the lid receiving frame set for underground structures shown to the same figure (a). It is a top view. The cross-sectional view shown in FIG. 1A is a cross-sectional view taken along the line AA in FIG. Hereinafter, the lid receiving frame set for underground structures may be abbreviated as a lid receiving frame set. 1A shows the ground G, the ground G may be omitted as shown in FIG. 1B in order to simplify the drawing.

  FIG. 1 shows a lid receiving frame set 10 including a manhole cover 2 corresponding to an embodiment of the lid for an underground structure of the present invention and a cylindrical receiving frame 3 that supports the manhole cover 2. . A sewer drain pipe, which is an underground buried object, is buried at a predetermined depth from the ground surface, and a manhole is provided as an underground facility in the middle of the sewer drain pipe. Both sewer drains and manholes are equivalent to underground structures. The manhole is formed as a vertical hole from the sewer drain pipe to the surface of the earth by using a box made of ready-made concrete moldings. The receiving frame 3 is provided on the housing and defines an opening H connected to a manhole that is an underground structure.

  The manhole cover 2 has a circular shape in a plan view so as to freely open and close the opening H connected to the manhole which is an underground structure, and the manhole cover 2 shown in FIG. It is out. Hereinafter, the state shown in FIG. 1 of the manhole cover 2 fitted to the receiving frame 3 and closing the opening H may be referred to as a fitted state. The manhole cover 2 shown in FIG. 1 is made of cast iron formed by casting. The manhole cover 2 may be made of iron other than cast iron, or may be made of metal other than iron, resin, or concrete.

  FIG. 2 is a rear view of the manhole cover 2 shown in FIG. In FIG. 2, a line corresponding to the AA line shown in FIG. 1B is shown as an A'-A 'line.

  As shown in FIGS. 1 and 2, the manhole cover 2 protrudes downward from the disk-shaped disk portion 21, a side surface 22 (see FIG. 2) provided on the outer peripheral portion of the disk portion 21, and the disk portion 21. And ribs 23 arranged in a cross pattern. In addition, the disk part 21 has the upper surface 21a which becomes the ground side, and the lower surface 21b which becomes the underground side. The rib 23 is formed integrally with the disk portion 21 and the side surface 22 when the manhole cover 2 is cast for the purpose of increasing the strength of the manhole cover 2. The side surface 22 will be described in detail later.

  The receiving frame 3 is made of cast iron formed by casting, and has a cylindrical shape formed in an annular shape in plan view having an inner peripheral surface 31 and an upper end surface 32. As shown in FIG. 1A, the receiving frame 3 is embedded with the upper end surface 32 exposed to the ground G. A hinge 311 is formed on one end side (right side in the drawing) of the inner peripheral surface 31 of the receiving frame 3, and a locking piece 312 is formed on the other end side (left side in the drawing) of the inner peripheral surface 31. ing.

  As shown in FIG. 1A, a hinge member 4 is rotatably connected to a peripheral edge portion on one end side (right side in the figure) of the disk portion 21 of the manhole cover 2. The hinge member 4 includes a hook-like protrusion 41 formed at an intermediate portion thereof and a retaining protrusion 42 formed at a lower end portion thereof. A hinge 311 formed on the inner peripheral surface 31 of the receiving frame 3 is provided with a through hole 311a through which the hinge member 4 passes in the vertical direction and a locked portion 311b. The locked portion 311b is a portion where the hook-shaped protrusion 41 of the hinge member 4 is locked. The retaining protrusion 42 comes into contact with the hinge 311 when the manhole cover 2 is lifted, and the manhole cover 2 can be lifted until the retaining protrusion 42 contacts the hinge 311.

  On the other hand, a key hole 211 is provided on the peripheral edge of the other end side of the disk portion 21. Further, the lock member 5 is provided on the other end side of the lower surface of the disk portion 21 so as to be rotatable about a rotation shaft 51. The lock member 5 has a valve body 52 and a locking claw 53. The lock member 5 is urged clockwise by a spring 54 in the drawing. In the posture of the lock member 5 shown in FIG. 1A, the valve body 52 enters the key hole 211 and closes the key hole 211. The hinge member 4 and the lock member 5 are not shown in FIG.

  In order to open the manhole cover 2 with the opening H closed as shown in FIG. 1, a rod-shaped opening / closing tool (not shown) is used. First, the tip of the opening / closing tool is inserted into the key hole 211 closed by the valve body 52. The valve body 52 is pushed by the tip portion of the opening / closing tool, and the lock member 5 opposes the urging force of the spring 54 so that the locking claw 53 moves away from the locking piece 312 (counterclockwise in FIG. 1A). In the direction) about the rotation shaft 51. Next, the tip end portion of the rod-shaped opening / closing tool is engaged with the edge portion of the key hole 211 on the lower surface 21b of the disk portion 21, and the opening / closing tool is pulled up. Then, the locking claw 53 is not locked to the locking piece 312, and the other end side of the manhole cover 2 is lifted, and the manhole cover 2 can rotate together with the hinge member 4 with the hinge member 4 as a fulcrum. That is, the manhole cover 2 can be turned in the substantially horizontal direction with the hinge member 4 as a fulcrum.

  Further, in the fitting state shown in FIG. 1, that is, when the opening H is blocked by the manhole cover 2, if water exceeding the flow capacity flows into the sewer pipe due to heavy rain, etc., the air pressure and water pressure (internal pressure) in the manhole ) Will rise.

  On the other hand, FIG. 3 shows a state where the internal pressure of the manhole has risen and the manhole cover 2 shown in FIG.

  When the internal pressure of the manhole rises, a pressure is applied to lift the manhole cover 2 as indicated by an arrow in FIG. In FIG. 3, the manhole cover 2 floats, the hook-like projection 41 of the hinge member 4 is locked to the locked portion 311 b of the hinge seat 311, and the locking claw 53 of the lock member 5 is engaged with the receiving frame 3. A state of being locked to the stop piece 312 is shown. In this state, the engagement between the hook-like projection 41 of the hinge member 4 and the locked portion 311b of the hinge seat 311 and the engagement between the locking claw 53 of the lock member 5 and the locking piece 312 of the receiving frame 3 are released. Unless this is done, the manhole cover 2 cannot float any further. Hereinafter, the flying position of the manhole cover 2 shown in FIG. 3 may be referred to as a limit flying position, and the flying height h of the manhole cover 2 shown in FIG. 3 may be referred to as a limit flying height h. In the present embodiment, the limit flying height h is set to about 15 mm, for example.

  FIG. 4A is a cross-sectional view taken along the line BB in FIG. In FIG. 2, a line corresponding to the BB line in FIG. 1B is shown as a B′-B ′ line. FIG. 4B shows a state where the internal pressure of the manhole has risen, and the manhole cover 2 shown in FIG. 4A has floated to the limit ascent position as the manhole cover 2 shown in FIG. In FIG. 4 and FIG. 7 described later, the rib 23 of the manhole cover 2 is omitted.

  As shown to Fig.4 (a), the taper part 313, the frame side extension part 314, and the stop part 315 are provided in the description on the inner peripheral surface 31 of the receiving frame 3 from the upper end surface 32 side to the underground side. . The tapered portion 313 is a tapered inner peripheral surface that is inclined outward as it goes upward and is connected to the upper end surface 32. The frame side extending portion 314 is a cylindrical inner peripheral surface that is connected to the lower end portion of the tapered portion 313 and extends in a direction orthogonal to a line connecting the upper end surfaces 32 of the receiving frame 3. In addition, it is good also as an aspect which comprises all the parts from the upper end surface 32 to the stop part 315 by the taper part 313, and abbreviate | omits the frame side extension part 314. FIG. The stop portion 315 is a portion protruding in a ring shape inside the receiving frame 3 from a position lower than the frame side extending portion 314, and stops the manhole cover 2 from falling into the receiving frame 3 due to repeated vehicle weight. It is.

  The side surface 22 of the manhole cover 2 is provided with a fitting portion 221 and a lid side extending portion 222 extending downward from the fitting portion 221. The fitting portion 221 is a tapered outer peripheral surface that is inclined outward as it goes upward and is connected to the upper surface 21a. The lid side extending part 222 is an outer peripheral surface that extends in a direction orthogonal to the upper surface 21 a of the manhole cover 2. In addition, it is good also as an aspect which comprises the side surface 22 of the manhole cover 2 only by the fitting part 221 and abbreviate | omits the cover side extension part 222. FIG. In the fitted manhole cover 2 shown in FIG. 4A, the fitting portion 221 is fitted to the tapered portion 313 of the receiving frame 3. In the fitted state, the entire fitting portion 221 may be fitted into the receiving frame 3 or a part thereof may be separated from the receiving frame 3. Further, the portion of the fitting portion 221 that fits with the receiving frame 3 may change depending on the fitting force and durability of the manhole cover 2.

  The first effect of the frame-side extension part 314 and the lid-side extension part 222 is that the opposing frame-side extension part 314 and the lid-side extension part 222 regulate when the internal pressure of the manhole rises rapidly. The manhole cover 2 can be lifted in a substantially horizontal posture. As a second effect, the manhole cover 2 is regulated and converged by the frame side extending portion 314 and the lid side extending portion 222, and the upper end surfaces of the manhole cover 2 and the receiving frame 3 can be aligned, and a correct fitting structure Can keep. As a third effect, it is possible to prevent sliding up. Here, when the load is locally applied to the peripheral portion of the manhole cover 2, the sliding-up portion of the manhole cover 2 is lowered while the opposite side portion of the manhole cover 2 is raised. It means a state that ends up.

  When the manhole internal pressure rises and the manhole cover 2 rises to the limit ascent position as shown in FIG. 4 (b), the fitting portion 221 of the manhole cover 2 and the taper portion 313 of the receiving frame 3 are disengaged, A gap is generated between the side surface 22 of the manhole cover 2 and the inner peripheral surface 31 of the receiving frame 3. However, since this gap is a minute space, only a small amount of fluid is discharged from this gap.

  Here, even after the manhole cover 2 rises to the limit ascent position, if the internal pressure is not sufficiently released and the internal pressure continues to rise, the lock member 5 and the hinge member 4 will eventually be damaged and the manhole cover 2 will be scattered. May end up. The present invention provides an internal pressure release port for discharging a fluid such as gas or liquid when the manhole cover 2 is lifted by the internal pressure, and releases the internal pressure by discharging the fluid from the internal pressure release port to suppress the scattering of the manhole cover 2. It is about to try. An example of the internal pressure release port is shown in FIG.

  As shown in FIG. 2, the side surface 22 of the manhole cover 2 is provided with a plurality of internal pressure release portions 7 at intervals in the circumferential direction, and each of the internal pressure release portions 7 is provided with an internal pressure release port 7a. I have. In the present embodiment, six internal pressure release portions 7 are provided. The six internal pressure release portions 7 are arranged at equal intervals (45 ° intervals) in the circumferential direction including the key hole 211 and the hinge installation portion 212, and the internal pressure release ports 7a are provided at positions facing each other by 180 °. Yes. Further, in the manhole cover 2, three internal pressure release ports 7a provided on the left side in FIG. 2 are provided at equal intervals (45 degree intervals) in the circumferential direction, and three internal pressure release ports provided on the right side in FIG. 7a is also provided at equal intervals (45 degree intervals) in the circumferential direction. That is, in the present embodiment, the internal pressure release port 7a is provided at a point target position with respect to the center point O of the manhole cover 2, and there is a circumferential interval in the plurality of internal pressure release ports 7a. Two sets of three internal pressure release ports 7a arranged to be equal are included. It is also possible to adopt a mode in which the arrangement of the internal pressure release ports 7a is changed as shown by the one-dot chain line in FIG. 2 and the six internal pressure release ports 7a are provided at regular intervals (60 degree intervals) in the circumferential direction.

  In FIG. 2, one internal pressure release part 7 is shown enlarging and encircled by a circle. As shown in an enlarged circle, the internal pressure release portion 7 is provided with an internal pressure release port 7a that opens to the side surface 22, a release channel 7b that is connected to the internal pressure release port 7a, and the release channel 7b. And a pair of second reinforcing ribs 73 provided on the outside of the pair of first reinforcing ribs 72, 72.

  The release flow path 7b extends in the radial direction of the disk portion 21, and the upper determination surface 71 that defines the upper side of the release flow path 7b has a portion on the outer peripheral side of the disk portion 21 at the internal pressure release port 7a. It is comprised by the curved surface which protruded as it went (refer FIG.5 (b) etc.). Each of the pair of first reinforcing ribs 72 and 72 and the pair of second reinforcing ribs 73 and 73 protrudes downward, and the inner first reinforcing rib 72 is more than the outer second reinforcing rib 73. The amount of protrusion is set large. In addition, these 1st reinforcement rib 72 and the 2nd reinforcement rib 73 are for compensating the strength fall of the side surface 22 by providing the internal pressure release port 7a.

  Fig.5 (a) is CC sectional view taken on the line of FIG.1 (b). In FIG. 2, the line corresponding to the line CC in FIG. 1B is shown as a C′-C ′ line. As can be seen from this positional relationship, in FIG. The state which cut | disconnected by the line which connects a pair of internal pressure release port 7a each provided in the position to show is shown. FIG.5 (b) is an enlarged view which expands and shows the D section of the figure (a).

  As shown in FIG. 5B, in the portion of the side surface 22 where the internal pressure release port 7 a is provided, the narrow fitting portion 221 a located on the internal pressure release port 7 a is fitted to the taper portion 313 of the receiving frame 3. doing. The internal pressure release port 7a is closed at the top, and in the fitted state shown in FIG. 5B, the entire internal pressure release port 7a opens toward the inner peripheral surface 31 of the receiving frame 3, but the manhole cover There is no gap between the two side surfaces 22 and the inner peripheral surface 31 of the receiving frame 3.

  FIG. 6 is a view of the side surface 22 of the manhole cover 2 as viewed from the front of the internal pressure release port 7a. As shown in FIG. 6, the internal pressure release port 7 a is cut out from the lower end of the side surface 22 and opens in a substantially rectangular shape. In the present embodiment, the internal pressure release port 7 a is provided from the lid side extending part 222 to the fitting part 221. 5B and FIG. 6, the opening height t2 of the internal pressure release port 7a is set to about 3/4 of the thickness t of the side surface 22 of the manhole cover 2, and the narrow fitting portion The thickness t1 of 221a is set to about ¼ of the thickness t of the side surface 22 of the manhole cover 2. Specifically, when the thickness t of the side surface 22 of the manhole cover 2 is about 40 mm, the thickness t1 of the narrow fitting portion 221a is set to about 10 mm, and the opening height t2 of the internal pressure release port 7a is set to about 30 mm. doing. In addition, thickness t1 of the narrow fitting part 221a can be suitably adjusted in 5 mm or more and less than 20 mm. Further, the shape of the internal pressure release port 7a is not particularly limited. For example, the internal pressure release port 7a may be formed in a trapezoidal shape as shown by a two-dot chain line in FIG. 6, or as shown by a one-dot chain line in FIG. The part may be formed in a semicircular shape.

  FIG.5 (c) has shown the mode that the manhole cover 2 shown to the same figure (b) floated to the limit floating position similarly to FIG. Further, in FIG. 6, the position of the upper end surface 32 of the receiving frame 3 when the manhole cover 2 is lifted to the limit ascending position is indicated by a thick two-dot chain line, and the inner pressure release port 7 a is above the upper end surface 32 of the receiving frame 3. The opening located at is shown by shading.

  As described above, the upper determining surface 71 that defines the upper side of the release flow path 7b is configured by a curved surface that protrudes as the outer peripheral portion of the disk portion 21 moves toward the internal pressure release port 7a. For this reason, in the state where the manhole cover 2 floats and the internal pressure release port 7a is positioned above the upper end surface 32 of the receiving frame 3, the fitting portion 221 serving as an opening for discharging gas and liquid, and the receiving frame 3 The distance between the upper defined surface 71 and the tapered portion 313 of the receiving frame 3 is larger than the distance between the tapered portion 313 and the distance between the upper defined surface 71 and the tapered portion 313 of the receiving frame 3 is downward. It gets bigger as you go. Thereby, the space connected to the internal pressure release port 7a can be sufficiently secured, and the gas or liquid rising to the manhole cover 2 can be smoothly discharged from the internal pressure release port 7a.

  When the internal pressure of the manhole rises and the manhole cover 2 rises from the closed state shown in FIG. 1, the gas or liquid that has risen up to the manhole cover 2 becomes the upper definite surface 71 as shown by the arrow in FIG. Along the release flow path 7b and is discharged laterally from the internal pressure release port 7a. Thereby, the internal pressure of a manhole can be released. Further, as described above, in the present embodiment, the plurality of internal pressure release ports 7a are provided at positions that face each other by 180 degrees. Thereby, when the fluid is discharged from each internal pressure release port 7a, the parallel balance of the manhole cover 2 that has floated is maintained, and the inclination is suppressed. As a result, it is possible to avoid the problem that the manhole cover 2 is inclined and it becomes difficult to discharge the fluid. In addition, it is possible to avoid the problem that the manhole cover 2 is inclined and the burden on the locking claw 53 of the lock member 5 and the hook-like protrusion 41 of the hinge member 4 is increased.

  In this embodiment, when the increase in the internal pressure of the manhole is relatively moderate, the fitting is held by the fitting force between the manhole cover 2 and the receiving frame 3. On the other hand, when the internal pressure of the manhole suddenly rises due to heavy rain, etc., the manhole cover 2 rises to the limit ascent position and discharges more fluid from the internal pressure release port 7a, so that the internal pressure is increased more quickly. Can be released.

  Here, the higher the limit flying height h, the more advantageous in terms of increasing the fluid discharge amount. On the other hand, in view of safety and the like, it is not preferable to increase the limit flying height h. According to the present embodiment, a part of the internal pressure release port 7a is opened above the upper end surface 32 of the receiving frame 3, and the fluid can be discharged from the opened part. As a result, even when the flying height of the manhole cover 2 is suppressed, the fluid can be efficiently discharged compared to the conventional mode in which the outflow is caused through the gap between the fitting surface of the cover for the underground structure and the tapered portion of the receiving frame. Can be discharged. Furthermore, since the upper part of the internal pressure release port 7a is closed, the fluid discharged from the internal pressure release port 7a is difficult to move upward, and there is little possibility of promoting the scattering of the manhole cover 2.

  In addition, when the limit flying height h is constant, as the thickness t1 of the narrow fitting portion 221a is decreased, the exposed height t3 of the internal pressure release port 7a is increased, and more fluid can be discharged. it can. On the other hand, when the thickness t1 of the narrow fitting portion 221a is reduced, the fitting area between the manhole cover 2 and the receiving frame 3 is reduced, and the fitting force between the manhole cover 2 and the receiving frame 3 becomes insufficient. There is a high risk that the odor in the manhole will be discharged to the outside. For this reason, in order to discharge the fluid more efficiently while ensuring the fitting between the manhole cover 2 and the receiving frame 3 and suppressing the discharge of odor to the outside, the thickness t1 of the narrow fitting portion 221a is It is preferable to set it to 1/5 or more and 3/4 or less of the limit flying height h.

  FIG. 7 is a cross-sectional view taken along the line EE of FIG. In FIG. 2, a line corresponding to the line EE in FIG. 1B is shown as an E′-E ′ line. As shown in FIG. 1, the manhole cover 2 is provided with two prying holes 213, and FIG. 7 shows a cross section taken along a line passing through one of the prying holes 213.

  Since the manhole cover 2 is not opened for a long period of time, the fitting portion 221 of the manhole cover 2 and the taper portion 313 of the receiving frame 3 are tightly fitted to each other by the repeated load such as rusting or passing of the vehicle. This is a hole for inserting a bar-shaped opening / closing tool (not shown) to pry when the manhole cover 2 is difficult to open.

  Some conventional prying holes are formed as through holes penetrating the disk portion 21 of the manhole cover 2, which is one of the causes of odors in the manhole being discharged to the outside.

  As shown in FIG. 7, the bottom hole portion 213 of the present embodiment is surrounded by a bottom wall portion 2131 in a bag shape. For this reason, it can also prevent that the odor etc. in a manhole are discharged | emitted outside.

  Next, a modified example of the lid receiving frame set 10 described so far will be described. In the following description of the modified example, differences from the embodiment shown in FIGS. 1 to 7 will be mainly described, and the components having the same names as those of the components described so far are denoted by the same reference numerals. A description will be given, and duplicate descriptions may be omitted.

  FIG. 8A shows a first modification of the lid receiving frame set 10, and FIG. 8B shows a second modification of the lid receiving frame set 10. FIG. 8 shows a portion corresponding to FIG. 5C, and the manhole cover 2 shows a state where the manhole cover 2 has floated to the limit ascent position.

  As shown in FIG. 8 (a), in the first modified example, compared with the embodiment shown in FIG. 5, the inner pressure release port 7a side portion of the upper determination surface 71 of the internal pressure release portion 7 is cut away to release the internal pressure. The release flow path 7b toward the mouth 7a is formed large. As described with reference to FIG. 6 and various forms of the shape of the internal pressure release port 7a, the shape of the upper determination surface 71 is not limited. For example, it may be formed in a curved shape that is recessed upward as shown by a one-dot chain line in FIG. 8A, or may be formed in a curved shape that protrudes downward as shown by a two-dot chain line.

  In the second modification, there is provided a flow hole 74 that extends in the radial direction of the disk portion 21 and opens from the fitting portion 221 to the lid-side extension portion 222 on the side surface 22 as shown in FIG. It has been. In the second modification, this opening becomes the internal pressure release port 7a, and the space defined by the flow hole 74 becomes the release channel 7b. In addition, as shown with the dashed-two dotted line of FIG.8 (b), it is good also as an aspect which provides the through-hole 74 opened to the fitting part 221 of the side surface 22. FIG.

According to the manhole cover 2 and the cover receiving frame set 10 including the manhole cover described above, the internal pressure can be efficiently released by securing the fluid discharge amount, and the scattering of the manhole cover 2 can be suppressed. The present invention is not limited to the embodiment, and various modifications can be made within the scope described in the claims. For example, in the above-described embodiment, the internal pressure release port 7a is described as an example in which the internal pressure release port 7a is opened to the side, but the internal pressure release port 7a may be opened obliquely upward. Good.

  In addition, even if it is a structural requirement contained only in each description of each modification demonstrated above, the structural requirement may be applied to embodiment and another modification.

DESCRIPTION OF SYMBOLS 10 Cover frame set 2 Manhole cover 21 Disk part 21a Upper surface 22 Side surface 221 Fitting part 221a Narrow fitting part 222 Cover side extension part 3 Receiving frame 31 Inner peripheral surface 313 Tapered part 314 Frame side extension part 7 Internal pressure release part 7a Internal pressure release port 7b Release flow path 71 Upper fixed surface H Opening h Limit flying height t3 Expressed height

Claims (5)

An upper surface on the ground side that closes the opening that leads to the underground structure,
A side surface provided with a fitting portion that fits to the inner peripheral surface of the receiving frame embedded with the upper end surface exposed to the ground,
The side surface is provided with an internal pressure release port that opens toward the inner peripheral surface when the upper portion is closed and the fitting portion is engaged with the inner peripheral surface of the receiving frame. Cover for underground structures.   The lid for an underground structure according to claim 1, wherein the internal pressure release port is formed by cutting out a lower end of the side surface.   3. The underground structure according to claim 1, wherein the internal pressure release port is provided at a point-symmetrical position with respect to a center point of the underground structure lid on the side surface. 4. lid.   The lid for an underground structure according to any one of claims 1 to 3, further comprising a release channel formed between a pair of ribs protruding downward and connected to the internal pressure release port. A receiving frame embedded with the upper end surface exposed to the ground;
A cover for an underground structure having a side surface provided with a fitting portion to be fitted to the inner peripheral surface of the receiving frame;
The side of the lid for the underground structure is provided with an internal pressure release port that is closed at the top and opens toward the inner peripheral surface when the fitting portion is fitted to the inner peripheral surface of the receiving frame. A lid receiving frame set for underground structures.