JP6414871B2 - Manhole floating prevention structure and construction method - Google Patents

Description

  The present invention relates to a levitation prevention structure for preventing a manhole that may be generated particularly during an earthquake from levitation from the ground, and a construction method thereof.

  During the earthquake, manholes have emerged, causing damage to sewers and causing traffic problems. Many manholes are caused by an increase in buoyancy due to an increase in excess pore water pressure associated with ground liquefaction during an earthquake. However, manhole levitation does not necessarily occur only due to an increase in excess pore water pressure associated with ground liquefaction, but may also occur due to an increase in groundwater pressure associated with an increase in groundwater level.

  As a method for preventing the manhole from rising, there are a safety pipe method, a manhole flange method, and an anchor wing method. For example, in the safety pipe method, a through hole is formed in the wall surface of a manhole, and a valve that is opened when a preset pressure is detected in the through hole is disposed. And when the excess pore water pressure exceeds the pressure set in the valve with the liquefaction of the ground, the valve opens and drains the ground water into the manhole to dissipate the excess pore water pressure. .

  In the manhole flange method, the apparent specific gravity is increased by fixing a heavy flange made of cast iron or concrete lump to the outer wall of the manhole. And even if the excess pore water pressure increases with the liquefaction of the ground, the weight of the manhole counteracts this water pressure to prevent floating.

  In the anchor wing method, the anchor body is rotated and inserted into the fixing layer of the ground, and a cantilever head fixing bracket is fixed to the outer wall of the manhole, and the anchor body and the head fixing bracket are fixed by a rod. It is connected. For this reason, the manhole is fixed to the fixing layer via the rod and the head fixing bracket, and even if the excess pore water pressure rises due to liquefaction of the ground, the manhole rises against this water pressure. It is a technology to prevent.

  Several proposals have been made for the safety pipe construction method and the manhole flange construction method described above, but there are few proposals for the anchor wing construction method. Moreover, although these construction methods are advantageous to be constructed when a new manhole is newly established, there is a problem that it is not easy to construct an existing manhole.

  In particular, in the case of the anchor wing method, since the wing is disposed horizontally, a bending moment is generated according to the acting buoyancy. In order to counter this bending moment, the wing needs to have high rigidity, and the material and the cross-sectional shape are complicated, and the structure of the joint portion with the manhole is complicated.

  An object of the present invention is to provide a levitation preventing structure that can prevent a levitation by fixing a manhole to a natural ground, and a construction method that can be constructed without causing a major problem even with an existing manhole. There is.

In order to solve the above-described problems, the manhole levitation preventing structure according to the present invention is a structure for preventing the manhole buoyed in the ground from penetrating and formed in the side wall of the manhole obliquely downward. It is arranged at a position that passes through the hole and obliquely below and avoids the pipe line connected to the manhole, the front end is fixed on the ground around the manhole, and the rear end is provided on the mounting member to cover the through hole. It has a supporting member attached to the side wall of the manhole through a seat plate .

In the levitation prevention structure, the mounting member is formed in a curved shape covering the through hole formed on the side wall of the manhole, and protrudes from the seat plate, and is inserted into the through hole. And a locking projection that protrudes from the cylindrical portion or the seat plate and engages with a groove formed on the side wall of the manhole.

In any one of the above-described manhole floating prevention structures, it is preferable that a plurality of the support members are arranged at substantially equal angular intervals on the circumference centering on the center of the manhole.

In any one of the above manhole floating prevention structures, it is preferable that the support member has a tip having an irregular shape.

In any one of the above manhole floating prevention structures, it is preferable that a hardened grout material is disposed around the support member and corresponding to the backfill soil layer and the ground.

  In any one of the manhole floating prevention structures described above, it is preferable that a space formed by the support member and a through hole formed in a side wall of the manhole is filled with an elastic material.

  Further, in any one of the manhole floating prevention structures described above, the through-hole formed in the side wall of the manhole has an outer diameter smaller than the inner diameter of the through-hole, and has a flange that is in contact with the inner wall of the manhole at one end. It is preferable that a cylinder body is formed in such a manner that the other end reaches the ground on the outer periphery of the manhole.

In addition, the manhole levitation prevention method according to the present invention forms a through-hole that is inclined downward at a position on the side wall of the manhole and avoids a pipe line connected to the manhole, and backfills the outer periphery of the manhole. A step of forming a hole that penetrates the earth and sand layer and reaches the ground below obliquely , and a support member is inserted into the hole from the through hole so that the tip reaches the ground and the rear end from the side wall of the manhole. A step of projecting, a step of filling the hole inserted through the support member with a grout material, a through hole formed in a side wall of the manhole and the support member after the grout material filled in the hole is cured A seat plate that fills the space constituted by the elastic material and the elastic material filled in the space constituted by the support member and then covers the through-hole provided at the mounting member at the rear end of the support member Through And attaching the side wall of the manhole,
It is characterized by having.

  In the manhole levitation prevention method, the step of forming a hole that penetrates the backfill soil layer on the outer periphery of the manhole and reaches the ground is equal to the diameter of the through hole formed in the side wall of the manhole or It is preferable to use a cylindrical casing having a small diameter and obliquely downward, and after inserting a support member into the casing, it is preferably filled with a grout material.

  In the manhole floating prevention structure according to the present invention (hereinafter, simply referred to as “floating prevention structure”), the support member disposed on the side wall of the manhole is fixed to the ground and the rear end of the manhole through the mounting member. Attached to the side wall. For this reason, the manhole is fixed and restrained on the natural ground via the support member, and even if the excess pore water pressure accompanying the liquefaction of the ground rises, it is possible to prevent the ascent against the rise. .

When the support member is disposed obliquely downward from the side wall of the manhole, a tensile force acts on the support member in accordance with the buoyancy acting on the manhole due to an increase in excess pore water pressure accompanying the liquefaction of the ground. For this reason, a solid steel bar can be employed as the support member.

  In particular, even when the excess pore water pressure rises by arranging a plurality of support members at substantially equal angular intervals on the circumference centering on the center of the manhole, it is possible to counteract evenly. Moreover, when the front-end | tip of a supporting member is formed in a different shape, a high-resistance can be implement | achieved because a deformed part engages with a natural ground. Furthermore, stable resistance can be realized by disposing a hardened grout material around the support member and corresponding to the backfill soil layer and ground.

  Further, the support member can be supported in a stable state by filling the space formed by the support member and the through hole formed in the side wall of the manhole with an elastic material.

  Further, the through hole formed in the side wall of the manhole is provided with a cylinder that has one end that is in contact with the inner wall of the manhole and the other end that reaches the ground on the outer periphery of the manhole. Even when a bending force or a tensile force is applied to the film, it can be sufficiently countered. For this reason, this cylinder can be utilized as a support member.

  In the manhole levitation prevention method (hereinafter simply referred to as “method”) according to the present invention, a through hole is formed at a position avoiding a pipe line on the side wall of the manhole, and the ground is formed by penetrating the backfill soil layer around the manhole. A grout material is formed in which a hole reaching the mountain is formed, a support member is inserted from the through hole into the hole, the tip reaches the ground, the rear end protrudes from the side wall of the manhole, and the hole inserted through the support member is filled. After curing, the manhole can be fixed to the natural ground via the support member by attaching the rear end of the support member to the side wall of the manhole via the attachment member.

It is a top view explaining the structure of a floating prevention structure. It is a figure which shows the relationship between a manhole and a supporting member, and is II-II sectional drawing of FIG. It is a figure explaining the example of the unusual shape of the front-end | tip part of a supporting member. It is a figure explaining the other example of the front-end | tip part of a supporting member. It is a figure explaining the example of a cylinder. It is a figure explaining the procedure of a floating prevention construction method. It is a figure explaining the procedure of a floating prevention construction method. It is a figure explaining the procedure of a floating prevention construction method. It is a figure explaining the other structural example of the floating prevention structure. It is a figure explaining the further another structural example of a floating prevention structure. It is a figure explaining the further another example of a floating prevention structure.

  Hereinafter, the floating prevention structure according to the present invention will be described. The levitation preventive structure according to the present invention counters the increased buoyancy acting on the manhole due to an increase in excess pore water pressure caused by the occurrence of fluidization of the ground during an earthquake, or an increase in groundwater pressure caused by any cause. Thus, it is possible to prevent ascent.

Floating preventing structure according to the present invention, through a through hole formed in the side wall of the manhole the support member is inserted toward the obliquely Me downward, fixing the distal end of the support member to the natural ground to be present in the outer circumferential region of the manhole The rear end is attached to the side wall. For this reason, the manhole is restrained by the natural ground via the support member, and even if a large buoyancy acts on the manhole as the excess pore water pressure increases or the groundwater pressure increases, the manhole rises against this buoyancy. It becomes possible to prevent.

  In the present invention, the “natural mountain” is a ground existing on the outer peripheral portion of the manhole, and means a natural earth and sand layer around the manhole and a backfill earth and sand layer familiar with the natural earth and sand layer. In addition, the “backfill soil layer” is a layer made of backfill earth and sand when the manhole is backfilled at the time of construction of the manhole, and is not yet familiar with the surrounding natural earth and sand layer. Means a layer that has the potential to float.

  In addition, the manhole structure for preventing levitation is not limited. It is an existing manhole, which is an integral manhole made of cast-in-place concrete, or a plurality of straight wall pipes stacked vertically and a slant wall at the top. Any of assembly manholes in which tubes are arranged may be used.

The support member is disposed obliquely Me downward through a through hole formed in the side wall of the manhole, as and disposed in a position to avoid the connected conduit on the manhole. When the support member is disposed obliquely downward, the angle is not particularly limited, and the work for forming the through hole in the side wall of the existing manhole can be performed smoothly and is possible with respect to the wall surface of the manhole. An acute angle is preferable. As described above, by arranging the support member at as acute an angle as possible, the workability of forming the through hole and connecting the support member is improved by utilizing the narrow internal space of the manhole. Is possible.

  When the support member is disposed obliquely downward, a tensile force and a bending force according to the downward angle and the buoyancy acting on the manhole are applied to the support member. For this reason, it is possible to employ a material having a required tensile strength without increasing the bending rigidity as the support member, and the cross-sectional shape can be simplified.

  In this case, the supporting member may be any member as long as it can support the buoyancy acting on the manhole as a tensile stress, and the shape and material are not limited. In particular, when the ground is liquefied, it is preferable that the tensile force acting on the individual support members be in the range of about 2 to 3 tons when the buoyancy acting on the manhole is countered. For this reason, as a supporting member, it is possible to selectively employ a rod or wire made of a metal material such as steel or stainless steel, or a rod made of a synthetic resin material containing reinforcing fibers.

Any support member that is disposed obliquely below needs to reach a natural ground whose tip is a stable ground. In the case where a manhole is newly established, it is possible to make the tip of the support member reach the natural ground prior to the formation of the backfill soil layer around the manhole, and the support member made of the various materials described above Can be selected. However, when the manhole is an existing one, it is necessary to make the tip of the support member pass through the backfill earth and sand layer and reach the ground, and a relatively high strength is required.

  The thickness of the support member disposed obliquely below is only required to exhibit the above-described tensile strength, and can be appropriately set according to the selected material. Usually, a support member having a thickness of about 12 mm to 30 mm is employed. Further, it is not limited whether the support member is a solid bar or has a hole penetrating in the axial direction. In particular, as will be described later, after the tip of the support member reaches the natural ground, when the ground material and the backfill earth and sand layer are filled with a grout material, a cylindrical rod having a hole penetrating in the axial direction is used. It is preferable that the grout material can be filled through the rod.

  The length of the support member is not limited, and may be any length as long as the tip can reach the ground and be fixed. Therefore, it is preferable that the length of the support member is set corresponding to the thickness and the arrangement angle of the backfill soil layer around the manhole. The support member is usually about 1.5 m to about 2.0 m, but is not limited to this range as described above. Further, it is preferable that the supporting member is formed in a rod shape having a unit length that can be easily operated inside the manhole, and this rod is connected by a connecting member to be long.

  Although the angle at the time of arrange | positioning a support member diagonally downward is not limited, It is preferable that it is the range of about 30 to 60 degree | times with respect to the perpendicular line of a manhole. However, when an already installed manhole is constructed in the anti-floating structure, the angle range is not necessarily required depending on conditions such as the inner diameter and depth of the manhole, but it is necessary to be obliquely below.

  The arrangement of the support members in the horizontal plane is a position where a pipe line connected to the manhole can be avoided, and is preferably a plurality of positions at substantially equal angular intervals. By arranging the plurality of support members at substantially equal angular intervals in this way, when buoyancy is applied to the manhole, it is possible to apply a load evenly to each support member, and to realize reliable ascent prevention. .

  It is preferable that the manhole can be prevented from rising by fixing to the natural ground only with a plurality of support members. However, it is not always necessary to prevent the manhole from rising only with the support member, and by forming a hardened layer made of a grout material around the support member, it may be configured to prevent floating with the hardened layer. .

  The material of the grout material is not particularly limited as long as it can be cured over time to cover or protect the support member. There is cement mortar as such a grout material, and if it is this cement mortar, it can be easily injected into a natural ground or backfill soil layer, and can be hardened with time to form a hardened layer. .

  In order to fix the support member to the ground, it is preferable that the tip of the support member has an irregular shape. The deformed shape of the tip portion of the support member is not particularly limited. However, when reaching the natural ground through the backfill earth and sand layer, it is preferable to easily press-fit the natural ground and have good fixability with the natural ground. As such a deformed shape, for example, a compacting bit attached to the tip of the support member or a position along the support member when press-fitting into a natural ground, it opens when the support member is moved back. It is preferable that the locking piece is hooked on the ground.

  The support member that forms a hardened layer of grout material around the periphery is preferably a cylinder having an axial through hole at the center, and when such a through hole is present, the tip of the support member reaches the natural ground. Thereafter, the grout material can be filled using the through hole. Moreover, it is preferable that the outer periphery of a supporting member is screw shape. By setting it as such a screw shape, it becomes possible to connect a some support member using a nut-shaped coupling. For this reason, it becomes possible to shorten the length of each support member, and the operation | work in a narrow manhole becomes easy. Furthermore, the adhesiveness with the grout material can be improved by the screw-like portion.

  When the through hole is formed on the side wall of the manhole, it is preferably formed in the manufacturing process of the manhole, but it is necessary to construct the manhole currently installed on site. The diameter of the through hole is not particularly limited, but the strength of the manhole itself is reduced as the through hole having a large diameter is formed, so there is a limitation naturally, and the diameter is about 40 mm to about 100 mm. It is preferable to form in a range.

  A grout material may be filled in a space formed by a through hole and a support member formed in the side wall of the manhole. However, the space is preferably filled with an elastic material. In this manner, by filling the elastic material, when a slight displacement occurs between the support member and the manhole, this displacement can be absorbed by the elastic material. Furthermore, it becomes possible to ensure water-stopping property by the elastic material.

  There is no limitation on what kind of elastic material is used, and the cylindrical rubber has an outer diameter slightly larger than the inner diameter of the through hole in advance and an inner diameter slightly smaller than the outer diameter of the support member. It is possible to use an elastic material such as. Further, it may be an elastic material such as urethane foam that seals the space by filling and foaming the space between the through hole and the support member.

  Next, an embodiment of the floating prevention structure will be described with reference to FIGS. As shown in FIG. 1, the levitating prevention structure A according to the present embodiment has a manhole 1 provided in a pipe B typified by a sewer pipe for increasing an excess pore water pressure or a groundwater pressure. It is configured so that it can be prevented from rising due to the accompanying buoyancy.

In the present embodiment, the support member 3 that is disposed obliquely downward through the through-hole 2 formed in the side wall of the manhole 1.

  The manholes 1 are installed at predetermined distances in the length direction of the pipeline B, and each manhole 1 has a size corresponding to the depth from the ground surface to the pipeline B. The manhole 1 is formed by excavating the natural ground C to form a vertical shaft with a preset depth, and stacking an invert block and several straight wall pipes and a slant wall pipe provided on the ground surface on the bottom plate. ing. And the backfill earth-and-sand layer D is comprised between the natural ground C by backfilling the circumference | surroundings of the installed manhole 1. FIG.

  A plurality of through holes 2 are formed on the side wall of the manhole 1 at positions where the pipe B can be avoided by penetrating the side wall, and a support member 3 is disposed in the through hole 2. The number of the through holes 2 is not particularly limited, but is preferably provided at a target position centered on the plane center of the manhole 1. In the present embodiment, it is formed at two places corresponding to the one-dot chain line 1a in FIG. 1, but it may be at four places indicated by the two-dot chain line 1b in FIG.

  The diameter of the through hole 2 is not particularly limited, and is preferably set so as to have an optimum diameter corresponding to conditions such as the thickness and type of the support member 3. Usually, as described above, it is selected from the range of about 40 mm to about 100 mm. The through hole 2 of this embodiment is formed with a diameter of about 60 mm.

  The support member 3 penetrates the through hole 2 and is disposed obliquely below. And the front-end | tip 3a of the supporting member 3 is fixing to the natural ground C through the through-hole 2 and the backfill earth-and-sand layer D, and the rear end 3b is a side wall of the manhole 1 via the attachment member 4 arrange | positioned in the through-hole 2. Attached.

  As described above, the inclination angle of the support member 3 (angle θ shown in FIG. 2) is not limited, but is set to about 45 degrees in this embodiment. However, when constructing the existing manhole on-site, it should be allowed that the inclination angle of the support member 3 does not necessarily fall within the set angle.

  As the support member 3, a cylindrical steel rod having an outer diameter of about 25 mm and an axial hole formed at the center is used, and the outer periphery is formed in a screw shape so as to improve adhesion to the grout material. Has been. Since the support member 3 is formed in a screw shape, the target support member 3 can be configured by connecting a support member material having a unit length to a desired length via a joint. Therefore, it is possible to set the supporting member 3 to a length corresponding to the conditions such as the thickness of the backfill soil layer D around the target manhole 1 and the distance to the stable ground in the ground C. It is. In the present embodiment, the support member 3 having an axial hole is used. However, as described above, a member having no axial hole may be used.

  Here, an example of a preferable support member 3 will be described with reference to FIGS. In FIG. 3A, a screw 3c is formed on the outer periphery, and a through hole 3d is formed in the axial direction. Further, the tip 3a is configured as a bit 3e capable of consolidating or excavating the support member 3 in the backfill soil layer D and the ground C. The bit 3e does not necessarily need to be formed by forming a part of the support member 3, and may be formed by fastening a pre-formed one via a screw 3c. The bit 3e constituting the tip 3a is provided with a hole 3f connected to the through hole 3d of the support member 3 on the side surface, and a grout material is discharged by using these holes 3d and 3f. It is possible to fill the backfill soil layer D. Then, when the hardened layer 5 made of the filled grout material is formed, the tip 3a having an irregular shape is formed by the remaining bit 3e and fixed to the natural ground C.

  Further, FIG. 3B is configured by a plurality of hooks 3g in which the tip 3a of the support member 3 is rotatable. In the tip 3 a configured as described above, when the support member 3 is press-fitted into the backfill soil layer D and the ground C, the plurality of hooks 3 g are located along the outer peripheral surface of the support member 3. When pulling back, it turns and catches on natural ground C. Accordingly, the plurality of hooks 3g constitute the tip 3a having an irregular shape, and the hook 3g is locked to the natural ground C, whereby the tip 3a is fixed.

  In the support member 3 shown in FIG. 4A, a plurality of slits 3h are formed along the longitudinal direction at the tip 3a, and a bridge piece 3i is formed between the adjacent slits 3h. The bridge piece 3i is formed with a bent line (not shown) in the circumferential direction so that it can be easily bent when an axial compressive force is applied. It is possible to discharge the grout material supplied from the respective slits 3h through the through holes 3d to fill the natural ground C and the backfill sediment layer D.

  The bridge piece 3i of the support member 3 is formed with a small width dimension and has a small bending rigidity, and can be bent in the outer peripheral direction by applying a force in the direction of the arrow shown in FIG. For this reason, if the force in the direction of the arrow is applied by pulling the tension member 3j disposed inside and connected to the tip portion of the support member 3 after discharging the grout material, the bridge piece 3i is applied according to the action of this force. As a result, a lantern-like bulged portion 3k is formed as a whole. And when the hardened layer 5 which consists of the filled grout material is comprised, the abnormal-shaped front-end | tip 3a is comprised by the bulging part 3k, and it fixes to the natural ground C. FIG. When a force in the direction of the arrow is applied to the support member 3, it is not always necessary to pull the tension member 3j, and the tip portion may be pressed against the ground.

  As described above, the tip 3a of the support member 3 is fixed to the ground C through the hardened layer 5 made of a hardened grout material. In this embodiment, cement milk is used as the grout material, and the hardened layer 5 is formed between the tip 3 a of the support member 3 and the outer wall of the manhole 1 to cover the entire length of the support member 3. That is, the hardened layer 5 is continuously formed up to the natural ground C through the backfill soil layer D.

The through hole 2 formed in the side wall of the manhole 1 is filled with an elastic material 6, and the rear end 3 b of the support member 3 is held through the elastic material 6. As the elastic member 6, urethane rubber previously formed with an outer diameter substantially equal to the inner diameter of the through-hole 2 and an inner diameter substantially equal to the outer diameter of the support member 3 is formed obliquely corresponding to the inclination angle of the support member 3. We use what we did. However, the elastic material 6 is not limited to a molded product of urethane rubber, and may be configured on site by filling the through hole 2 with a foaming agent such as urethane.

  The rear end 3 b of the support member 3 is attached to the inner peripheral surface of the side wall of the manhole 1 via the attachment member 4. The attachment member 4 includes a seat plate 4 a that covers the through hole 2 formed in the manhole 1, a cap nut 4 b that is screwed to the rear end 3 b of the support member 3, and a washer having an angle corresponding to the inclination angle of the support member 3. 4c.

The seat plate 4 a is formed in a curved shape having a size capable of covering the entire opening surface of the through hole 2 formed in the manhole 1, and is inserted into the through hole 2 on the surface facing the through hole 2. A cylindrical portion 4d to be projected is provided. Therefore, when the through hole 2 is filled with the elastic material 6 , the cylindrical portion 4d is inserted, the seat plate 4a is attached, and the cap nut 4b is fastened through the washer 4c, the opening surface of the through hole 2 is the seat plate 4a. Covered by. When the seat plate 4 a is about to be displaced in any direction with respect to the through hole 2, the cylindrical portion 4 d can come into contact with the inner peripheral surface of the through hole 2 to prevent the displacement.

  In the levitation prevention structure A configured as described above, when the buoyancy acts on the manhole 1 to try to levitate, the levitation can be prevented by the support member 3. In particular, since the tip 3a of the support member 3 penetrates the backfill soil layer D and is fixed to the natural ground C which is a stable ground, stable support can be realized.

  Further, when buoyancy is applied to the manhole 1, a tensile force is applied to the support member 3 according to the buoyancy. However, if the tip 3a of the support member 3 is formed in an irregular shape, the deformed portion is formed in the ground C. It becomes a resistance by being caught, and it is possible to prevent the flying more reliably.

  In addition, since the hardened layer 5 is formed around the support member 3, the hardened layer 5 and the ground C are buried between the support member 3 and the hardened layer 5 according to the tensile force acting on the support member 3. A frictional resistance is generated between the return soil layer D and acts as a resistance to prevent the manhole 1 from rising. For this reason, it becomes possible to further prevent the manhole from rising in a curable manner.

  Next, the structure of the cylinder which can be used for the above-mentioned levitation prevention structure A will be described with reference to FIG. The cylindrical body 7 shown in the figure is configured to be inserted into the through hole 2 of the manhole 1 so that the tip 7b can penetrate the backfill soil layer D and be fixed to the natural ground C. With this configuration, the manhole 1 It is possible to resist the shearing force acting on the boundary between the outer wall of the material and the backfill soil layer D.

  For this reason, the cylindrical body 7 has a cylindrical portion 7a made of a steel pipe having an outer diameter slightly smaller than the inner diameter of the through hole formed in the side wall of the manhole 1 and a length that can reach the natural ground C from the inner wall of the manhole 1. have. A flange 7c that is integrated by means such as welding and is in contact with the inner wall of the manhole 1 is provided at the end of the cylindrical portion 7a. Further, the flange 7c is provided with a nipple 7d having a seat integrated with a means such as welding and having an angle corresponding to the angle formed by the flange 7c and the cylindrical portion 7a. A hole 7e used for filling the grout material through the flange 7c and the nipple 7d is formed, and the hole 7e can be closed by attaching a cap nut 8 to the nipple 7d. Yes.

  When the cylindrical body 7 configured as described above is adopted, the flange 7c of the cylindrical body 7 is in contact with the inner wall of the manhole 1, and the tip 7b penetrates the backfill soil layer D and reaches the natural ground C. ing. For this reason, when the shear force and the tensile force generated at the boundary between the outer wall of the manhole 1 and the backfill soil layer D act on the cylinder 7 as the buoyancy acts on the manhole 1 and tries to lift, It is possible to prevent the manhole 1 from rising against this force.

  As described above, when the cylindrical body 7 is used, the cylindrical body 7 can be used as a support member, and it is not necessary to use the rod-shaped support member 3 as described above. Of course, it is also possible to use the support member 3 and the cylindrical body 7 together, and this does not prevent the combined use.

The tubular body 7, that is inserted into the through hole 2 formed obliquely downward to the side wall of the manhole 1.

  Next, a construction method for constructing the floating prevention structure A will be described with reference to FIGS. In the construction method according to the present invention, the stage at which the through hole 2 formed on the wall surface of the manhole 1 is processed is not limited. That is, when the manhole 1 is newly installed, it is possible to process the through-hole 2 on the straight wall pipe in advance at the factory stage. Further, when the manhole 1 is an existing one, it is necessary to process the through hole 2 at the installation site. In this embodiment, the existing manhole 1 is targeted.

  First, the through hole 2 is formed in the side wall of the manhole 1. This operation is performed by placing a core cutter (not shown) inside the manhole 1 at a preset angle and pressing the core cutter while rotating it.

  Next, as shown in FIG. 6 (a), a casing 10 for drilling is installed so as to face the through hole 2 formed in the manhole 1, and the backfill soil layer D, the ground is penetrated through the through hole 2. Drill toward C. The casing 10 is formed in a cylindrical shape having an outer diameter slightly smaller than the diameter of the through-hole 2, and a cutting edge 10 a that drills the earth and sand layer D and the natural ground C is provided at the tip. The casing 10 is configured to be driven by a driving device (not shown).

  And the casing 10 is hold | maintained diagonally downward at the preset angle, and the front-end | tip part containing the cutting blade 10a is made to face the backfill earth-and-sand layer D through the through-hole 2. FIG. Thereafter, the casing 10 is moved forward to advance through the backfill soil layer D into the natural ground C. It is also possible to form the through hole 2 on the side wall of the manhole 1 using the casing 10.

  In addition, the earth and sand excavated at the same time as drilling by the casing 10 is discharged from the internal space of the casing 10. When discharging the excavated earth and sand, it is possible to supply water from the outside to the inside of the casing 10, and to discharge it along with the water distribution to the manhole 1. Further, a screw may be provided inside the casing 10 and discharged.

  After the casing 10 is advanced to a preset length (depth) and the backfill soil layer D and ground C are drilled, as shown in FIG. The support member 3 is inserted. At this time, it is preferable that a ring-shaped collar (not shown) is attached to the outer periphery of the support member 3 so that the support member 3 is positioned substantially at the center of the casing 10.

  Next, as shown in FIG. 7A, while the casing 10 is pulled back to the manhole 1, a cement milk 5a serving as a grout material for forming the hardened layer 5 on the ground mountain C and the backfill soil layer D is filled. At this time, the cement milk 5a supplied through the hole formed in the support member 3 can be discharged and filled from the tip 3a. It is also possible to insert a hose (not shown) into the casing 10 together with the support member 3 and fill the cement milk 5a supplied through the hose.

  Furthermore, the filling of the cement milk 5a into the natural ground C and the backfill soil layer D can be performed from both the support member 3 and the casing 10. Thus, it is preferable that the filling method of the cement milk 5a is appropriately selected in consideration of conditions such as the dimensions of the supporting member 3 and the casing 10 to be employed, or the length of the supporting member 3 to the tip 3a.

  As described above, in this embodiment, the casing 10 is pulled back when the cement milk 5a is filled. However, whether or not the casing 10 is pulled back to the manhole 1 is not limited, and is preferably determined in accordance with the properties of the backfill soil layer D existing around the manhole 1. For example, the casing 10 may be pulled back to the manhole 1 when the backfilled soil layer is sufficiently familiar with the surrounding natural soil layer and exists as a natural ground C that is a stable ground.

  However, when the backfill soil layer D still has the possibility of liquefying without sufficiently adapting to the surrounding natural soil layer, it is preferable to bury the casing 10 without returning it to the manhole 1. When the casing 10 is to be buried, a large number of holes are formed in the side surface of the casing 10 and the filled cement milk 5a can be leached into the backfill soil layer D and the natural ground C through the holes. It is preferable to do so.

  When the cement milk 5a is filled into the natural ground C and the backfilling earth and sand layer D, the through hole 2 formed in the side wall of the manhole 1 is left in a space state. That is, when the cement milk 5a is once filled to the upper level on the outer peripheral surface side of the through hole 2 to substantially fill the through hole 2, and the filled cement milk 5a starts to harden, it exists inside the through hole 2. By removing the slightly hardened cement milk 5a, the through hole 2 is left in a space state. And as shown in FIG.7 (b), cement milk 5a hardens | cures with time and the hardening layer 5 is comprised.

After the hardened layer 5 is formed around the support member 3, as shown in FIG. 8, the through hole 2 of the manhole 1 is filled with the elastic material 6 so as to penetrate the rear end 3 b of the support member 3. Further, the seat plate 4 a is arranged on the inner peripheral surface side of the manhole 1 in the through hole 2, the rear end 3 b of the support member 3 is inserted, and the cylindrical portion 4 d is inserted into the through hole 2. Next, a washer 4c is inserted into the rear end 3b, and a cap nut 4b is screwed into the rear end 3b of the support member 3 to be fastened with a preset torque.

  Thus, by attaching the rear end 3b of the supporting member 3 to the side wall of the manhole 1 via the mounting member 4 by applying a preset force, the buoyancy acting on the manhole 1 can be reduced by the side wall and the seat plate 4a. It is possible to transmit to the support member 3 through the friction.

  Next, another example of the floating prevention structure will be described with reference to FIG. In the figure, the same reference numerals are used for the same parts and the parts having the same functions as those of the above-described embodiment, and the description thereof is omitted (the same applies hereinafter).

  As shown in the figure, a cylindrical body 7 is disposed in the through hole 2 formed in the side wall of the manhole 1, and the tip 7b of the cylindrical body 7 penetrates the backfill soil layer D and reaches the natural ground C. doing. Further, the flange 7c of the cylindrical body 7 is in contact with the inner wall of the manhole 1, and the inner space of the cylindrical portion 7a is filled with the grout material 5 and hardened.

  The step of inserting the cylindrical body 7 from the through hole 2 toward the natural ground C is performed by drilling the backfill earth and sand layer D and the natural ground C by the casing 10 using the through hole 2. This is preferably performed after pulling back to the manhole 1. Thus, an easy operation can be realized by inserting the cylindrical body 7 into a previously drilled portion.

  Then, after the flange 7c of the cylinder 7 is in contact with the inner wall of the manhole 1, a hose (not shown) is connected to the nipple 7d to fill cement milk as a grout material up to the flange 7c side. A small hole (not shown) is formed in the flange 7c, and when the cement milk filled in the cylinder portion 7a of the cylinder 7 reaches the frame 7c, the cement milk is completely filled by oozing out from the hole. .

  Therefore, the manhole 1 is constrained to the natural ground C by the rod-shaped cylinder 7 made of a grout material having the thickness of the cylinder portion 7a and the inside being hardened. Further, there is almost no gap between the cylindrical portion 7a and the inner surface of the through hole 2, and the flange 7c is in contact with the inner wall, whereby the manhole 1 and the cylindrical body 7 are substantially integrated. For this reason, when a relative displacement is about to occur between the manhole 1 and the cylindrical body 7, the forces acting at this time can be transmitted and supported, and the manhole 1 can be reliably restrained. Become.

  Next, still another example of the floating prevention structure will be described with reference to FIG. The manhole 1 shown in the figure is assembled by stacking a plurality of cylindrical straight wall tubes 15 and 16 having a unit length. The straight wall pipes 15 and 16 have flanges 15a and 16a, respectively, and maintain a stable assembled state by bringing the flanges 15a and 16a into contact with each other.

  The through-hole 2 is formed at a site where the straight wall pipes 15 and 16 are connected, and is a groove 15b at a predetermined position above and below the through-hole 2 on the inner peripheral surface of each straight wall pipe 15 and 16. , 16b are formed. The grooves 15b and 16b are necessary, but there may or may not be grooves in the left-right direction of the through hole 2.

  The support member 3 has a rear end 3 b that passes through the through hole 2 and is disposed inside the manhole 1, and is attached to the manhole 1 by an attachment member 4. The attachment member 4 includes a seat plate 17 that covers the through-hole 2, a cap nut 4 b that is screwed into the rear end 3 b of the support member 3, and a washer 4 c that has an angle corresponding to the inclination angle of the support member 3. ing.

  The seat plate 17 is formed in a curved shape having a size capable of covering the entire opening surface of the through hole 2 formed in the manhole 1, and is formed in the straight wall pipes 15 and 16 at both ends in the vertical direction. A locking projection 17a that fits into the grooves 15b and 16b is formed. Moreover, when the groove | channel is formed also in the left-right direction of the through-hole 2, the latching protrusion is also formed in the position facing these grooves. Further, a cylindrical portion 17 b that is inserted into the through hole 2 projects from the surface of the seat plate 17 that faces the through hole 2. However, when the locking projection 17a is formed on the seat plate 17, the cylindrical portion 17b may not be provided.

Then, the cylindrical plate 17b is inserted into the through hole 2 filled with the elastic material 6 , and the locking projection 17a is fitted into the grooves 15b and 16b formed in the straight wall tubes 15 and 16, and the seat plate 17 is attached. Is possible. Further, the cap nut 4b is fastened to the rear end 3b of the support member 3 protruding from the seat plate 17 via the washer 4c, so that the opening surface of the through hole 2 is covered with the seat plate 17 and the support member 3 is covered with the manhole 1. It is possible to attach to.

  In this example configured as described above, since the cylindrical portion 17b of the seat plate 17 is inserted into the through hole 2, when any external force acts on the straight wall pipes 15 and 16 to try to shift in the horizontal direction. The cylindrical portion 17b can be in contact with the inner peripheral surface of the through hole 2 to prevent displacement. Further, since the locking projections 17a of the seat plate 17 are locked in the grooves 15b and 16b formed above and below the through hole 2, the straight wall tubes 15 and 16 are relatively displaced in the vertical direction to form an interval. When trying to do so, the locking projection 17a can be engaged with the grooves 15b and 16b to prevent vertical displacement.

  FIG. 11 is a diagram for explaining still another configuration of the embodiment shown in FIG. In this embodiment, the cylindrical body 7 shown in FIG. 5 is deformed and applied to the connecting portion of the straight wall pipes 15 and 16 constituting the manhole 1. That is, a locking projection 7f that fits into the grooves 15b and 16b formed in the straight wall pipes 15 and 16 is formed at the end of the flange 7c of the cylindrical body 7. Even when such a cylindrical body 7 is applied to the connecting portion of the straight wall pipes 15 and 16, when the straight wall pipes 15 and 16 are relatively displaced in the vertical direction, an interval is formed. The protrusion 7f can be engaged with the grooves 15b and 16b to prevent vertical displacement.

  The structure for preventing a manhole from rising according to the present invention is advantageous when used for an existing manhole or a new manhole.

A Lifting prevention structure B Pipeline C Ground mountain D Backfill earth and sand layer 1 Manhole 2 Through hole 3 Support member 3a Front end 3b Rear end 3c Screw 3d Through hole 3e Bit 3f Hole 3g Hook 3h Slit 3i Bridge piece 3j Tensile member 3k Swelling Part 4 Mounting member 4a Seat plate 4b Cap nut 4c Washer 4d Tubing part 5 Hardened layer 5a Cement milk 6 Elastic material 7 Tubular body 7a Tubing part 7b Tip 7c Flange 7d Nipple 7e Hole 7f Locking projection 10 Casing 10a Cutting edge 15 Straight wall pipe 15a, 16a Flange 15b, 16b Groove 17 Seat plate 17a Locking projection 17b Tube part

Claims (8)

It is a structure to prevent the rise of manholes buried in the ground,
While penetrating through a through-hole formed obliquely downward on the side wall of the manhole and disposed at a position obliquely downward and avoiding a pipe line connected to the manhole, the tip is fixed to a natural mountain around the manhole, A seat plate formed in a curved shape covering the through hole formed on the side wall of the manhole and a cylindrical portion inserted from the seat plate and inserted into the through hole or formed from the seat plate. A structure for preventing a manhole from floating, comprising: a support member attached to the side wall of the manhole through a seat plate of the attachment member having a locking projection engaged with a groove formed on the side wall of the manhole.   2. The manhole floating prevention structure according to claim 1, wherein a plurality of the support members are arranged at substantially equal angular intervals on a circumference centered on the center of the manhole.   The structure for preventing a manhole from floating according to claim 1 or 2, wherein the support member has a tip formed in a different shape.   The manhole levitation according to any one of claims 1 to 3, wherein a hardened grout material is disposed around the support member and corresponding to the backfill soil layer and ground. Prevention structure.   The space formed by the support member and a through hole formed in a side wall of the manhole is filled with an elastic material, and the manhole is prevented from rising. Construction.   The through hole formed in the side wall of the manhole has an outer diameter smaller than the inner diameter of the through hole, a flange that is in contact with the inner wall of the manhole is formed at one end, and the other end reaches a natural mountain on the outer periphery of the manhole. 6. A manhole floating prevention structure according to claim 1, wherein a cylindrical body is disposed. A through hole is formed at a position on the side wall of the manhole that avoids the pipe line connected to the manhole, and the penetrating soil layer on the outer periphery of the manhole is penetrated to reach the ground below the manhole. Forming a hole to be
Inserting a support member from the through hole into the hole to cause the tip to reach a natural ground and projecting the rear end from the side wall of the manhole;
Filling a grout material into the hole inserted through the support member;
After the grout material filled in the hole is cured, a step of filling an elastic material in a space formed by the through hole formed in the side wall of the manhole and the support member;
A step of attaching the rear end of the support member to the side wall of the manhole via a seat plate provided on the attachment member and covering the through hole after filling the space formed by the support member with an elastic material;
A manhole levitation prevention method characterized by comprising: The step of forming a hole that penetrates the backfill soil layer on the outer periphery of the manhole and reaches a natural mountain has a diameter equal to or smaller than the diameter of the through hole formed in the side wall of the manhole and is directed obliquely downward. Using a cylindrical casing,
8. The manhole levitation prevention method according to claim 7, wherein a grout material is filled after the support member is inserted into the casing.

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