JP4764084B2 - Seismic reinforcement method for existing manholes - Google Patents

Description

  This invention is to prevent an existing manhole laid with an entrance with a lid on the ground surface from rising or floating due to liquefaction of the ground directly under the earthquake etc. The present invention relates to a seismic reinforcement method and apparatus.

There exists patent 3340147 gazette as this kind of technique. The gazette describes that an excess pore water guideway is provided around the peripheral wall of the manhole laid under the ground surface so that excess water around the manhole flows into the manhole from the upper end of the guideway. .
Japanese Patent No. 3440107

  However, in such a procedure, the excess water around the manhole is excluded, and the manhole is lifted and floated due to the high pressure of liquefaction that goes directly under the manhole. There is a problem of end. In addition, there is a problem that it is extremely difficult to dig up around existing manholes and provide a deep guideway for excess water.

The present invention relates to an existing manhole laid as a sewerage facility with a doorway with a lid on the ground surface, penetrating from the upper surface of the peripheral shelf on the invert in the manhole through the bottom slab and the base portion below it. A plurality of vertical holes reaching the natural ground are provided, a hollow pipe is inserted into each vertical hole, the lower end of each hollow pipe is allowed to reach the natural ground, and the upper end of each hollow pipe is set above the groundwater level. In addition, a plurality of filtration nets are provided at intervals between the lower end and the middle in each hollow pipe, and at least one of the hollow pipes is made a transparent body that can be seen through, and the manhole is caused by an earthquake or the like. Only the moisture in the liquefaction energy that goes directly under or around the area and becomes high pressure is filtered up from the lower end of each hollow pipe and diffused from the upper end opening above the groundwater level, so that the liquefaction energy directly under the existing manhole is reduced. So as to prevent the push-up floating and sinking fluctuations of the existing manhole by pressure, it had to solve such problems.

  In the present invention, a person who works inside the existing manhole enters the ground below the manhole, and a hollow pipe with the upper end above the groundwater level is installed vertically, and an earthquake or the like directly below the manhole. Since the moisture in the generated liquefaction energy is filtered up and dissipated above the groundwater level, the manhole is controlled directly underneath the manhole, so that the rise and sinking fluctuation of the manhole due to the liquefaction phenomenon is reliably prevented. Produces the effect.

  Since all the seismic reinforcement work can be performed inside the existing manhole and excavation around the outside of the manhole is unnecessary, there is an effect that no traffic obstacles or the like occur during the seismic reinforcement work.

  Since the peripheral shelf part of the invert inside the existing manhole is used, there is an effect that the running function of the manhole is not hindered.

  Since the filtration net is inserted with a stopper at the lower end of the hollow pipe, the hollow pipe is not clogged with earth and sand, and the hollowing due to the rise of earth and sand directly under the manhole is prevented, and manhole subsidence fluctuations, etc. The effect that it does not occur is produced. The nets for filtration are provided in multiple rows such as three stages at intervals, and the size of the stitches is made smaller in order from the outer row, so that moisture is filtered step by step to clog the net. It does not occur, and the effect that the water filtration function can be remarkably improved as compared with the case where the same stitch nets are arranged in parallel is produced.

  By making one of the hollow pipes a transparent pipe that can be seen through, it is possible to check the change in the groundwater level on a daily basis by visually observing the water level in the pipe.

  A hollow is provided with a horizontal through hole at a position below the groundwater level on the peripheral wall of the manhole, and one end is inserted into the horizontal through hole from the inside of the manhole, and the other end opened vertically is above the groundwater level in the manhole. Provide a pipe to prevent moisture from the liquefaction energy around the manhole from rising into the manhole and controlling the liquefaction energy before entering the manhole to prevent liquefaction of the ground beneath the manhole. As a result, it is possible to prevent the manhole from being lifted and floated and subsidized.

  The present invention uses a peripheral shelf part of an invert part of an existing manhole that is laid as a sewerage facility with a doorway with a lid facing the ground surface, and passes the lower end from the top part of the shelf part through the foundation part under the bottom plate. A plurality of hollow pipes with their upper ends above the groundwater level are provided, and the water in the liquefied energy that has been generated or has come around under the manhole due to an earthquake, etc. in each hollow pipe is increased by filtration. In this way, the liquefaction energy is suppressed by dissipating it above the groundwater level to prevent the manhole from being lifted or floated or subsidized.

  Reference numeral 1 denotes an existing manhole installed as a sewerage facility, and 1a denotes an entrance / exit cover facing the ground surface. Using the peripheral shelves 3a and 3b outside the running water groove of the inner invert 2 placed on the bottom of the manhole 1, the bottom end of the base plate 1b and the base 4 below the bottom plate 1b are made to reach the ground 5 A plurality of vertical holes 6 are provided, and a hollow pipe 7 made of synthetic resin is inserted into each vertical hole 6 and vertically supported. The upper end of the hollow pipe 7 is positioned above the surrounding groundwater level. In addition, as shown in FIG. 3, each hollow pipe 7 may be bent on the peripheral shelf parts 3a and 3b, and may be along the inner wall face 1c of a manhole. The portion of the hollow pipe 7 along the inner wall surface 1 c may be formed integrally with the wall surface of the manhole 1. In this way, by extending the portion of the hollow pipe 7 in the manhole 1 along the inner wall surface 1c, the inside of the manhole 1 can be widened regardless of the vertical arrangement of the hollow pipes 7, and inspection, repair, etc. can be facilitated. Shall. Further, as shown in FIG. 5, a bent pipe 8 may be attached to the upper end of the hollow pipe 7 and piped from the side wall of the manhole 1 onto the external side groove 9.

  Reference numeral 10 denotes a filtration net that is attached to the lower end of the hollow pipe 7 so as to be exchangeable. Only the moisture in the liquefaction energy containing earth and sand is filtered and raised. As shown in FIG. 4, the net 10 is made of synthetic resin, stainless steel or the like, and a cylindrical body 10b provided with a hook-shaped stopper 10a on the outer periphery of the lower end so as to move within the hollow pipe and prevent troubles. In addition to being attached in three steps with a gap in the inside, as shown in FIGS. 4 (a) to (d), it is formed in various forms such as a stack of spherical bodies, hourglass bodies, bowls, etc., vertical rolls, etc. . Further, the net 10 to be attached in three stages or the like has a coarse stitch of the outer net 10 and a gradually fine stitch of the inner net 10, for example, an outer stitch 10 mm hole / intermediate stitch 5 mm hole / inner stitch 1 mm hole. By doing so, it is possible to gradually filter the water mixed with earth and sand to prevent clogging and to greatly improve the filtration function. The stitch size of the net 10 is selected from about 20 mm to about 1 mm, depending on the conditions such as the soil quality of the manhole installation location as well as the diameter and number of the hollow pipes 7.

  When the natural ground 5 directly under the existing manhole 1 is liquefied due to an earthquake or the like, or when liquefaction circulates directly under the manhole 1 from the surroundings and becomes high pressure, the water in the liquefaction energy is filtered through the net 10. The inside of the hollow pipe 7 is raised and diffused into the manhole 1 from the upper end above the groundwater level, or flows into the side groove 9 to suppress the area directly below the manhole 1 to the original state. Thus, it is possible to prevent a change in settlement due to pushing up and floating, or cavitation under the manhole.

  Since each hollow pipe 7 is provided with a filtering net 10 so as to raise only the moisture, the hollow pipe 7 is not clogged by the inflow of earth and sand, and the earth and sand immediately below the manhole 1 is left as it is. Therefore, the subsidence fluctuation of the existing manhole 1 accompanying the ground subsidence due to the hollowing of the natural ground 5 can be prevented. In addition, since the upper end of the hollow pipe 7 is positioned above the surrounding groundwater level, the groundwater does not normally flow into the manhole 1 from the upper end of the hollow pipe 7.

  If one of the hollow pipes 7 is a transparent pipe 7a that can be seen through, the water level in the pipe 7a can be visually checked to check the groundwater level around the manhole 1, and the groundwater level can be easily recorded. It will be possible to obtain.

  6 to 7 show an example in which the diameter of the water pipe 12 connected to the existing manhole 1 is large and there is no room for providing vertical holes in the peripheral shelves 3a and 3b of the inner invert 2. A plurality of horizontal through holes 15 are provided at a position below the ground water level of one peripheral wall 1d, one end is inserted into each horizontal through hole 15, and the other end opened vertically is set to the ground water in the manhole 1. The hollow pipe 7 is installed at a higher position. When liquefaction energy is generated around the manhole 1 due to an earthquake or the like and the pressure rises, moisture in the liquefaction energy is pressed through the horizontal through holes 15 and is gradually filtered through the net 10 and rises in the hollow pipe 7. The liquefaction energy around the manhole 1 is prevented from being accumulated by diffusing into the manhole 1 from the open end located above the groundwater level, and the liquefaction energy that goes directly under the manhole 1 is controlled in advance to lift and rise. I tried to prevent this.

  Although the above embodiment has described the construction of an existing manhole, the present invention can of course be applied to a new manhole. In the case of a new installation, a hole for a hollow pipe 7 is provided at the time of forming a manhole, and the precast invert 2 and the bottom plate 1a are installed on the site, and a vertical hole 6 is simply drilled in the foundation 4 and the ground 5 in accordance with this. Thus, the hollow pipe 7 is provided vertically in the manhole, and is laid as an earthquake-resistant structure as described above.

  As described above, the present invention can be widely used for many existing manholes and new manholes in which manholes are pushed up on the ground surface due to a liquefaction phenomenon caused by an earthquake or the like and fluctuations in subsidence are expected.

Longitudinal end view showing an embodiment of the present invention Same cross section Longitudinal sectional view showing an example in which each hollow pipe is bent on the peripheral shelf along the inner wall surface of the manhole Enlarged view showing the net part for filtration, (a) to (d) are other examples of formation of the net Partial sectional view showing an example in which a bent pipe is attached to the upper end of a hollow pipe and piped in an external gutter Partial longitudinal sectional view showing another embodiment Same cross section

Explanation of symbols

1 is a manhole 1a is a lid 1b is a bottom plate 1c is an inner wall surface 1d is a peripheral wall 2 is an invert 3a, 3b is a peripheral shelf 4 is a foundation 5 is a natural ground 6 is a vertical hole 7 is a hollow pipe 8 is a bent tube 9 is a side groove 10 Is a net-shaped stopper 10b is a cylinder 10b is a cylinder 11 is a step 12 is a water pipe 13 is a side hole 14 is a check valve 15 is a horizontal through hole

Claims (1)

In an existing manhole laid as a sewerage facility with an entrance with a lid on the ground surface, it reaches the ground directly below through the bottom slab and the underlying foundation from the upper surface of the peripheral shelf on the invert in the manhole. respective with a plurality of vertical holes provided, and inserting the hollow pipe to respective vertical holes, to reach the lower end of the respective hollow pipe to該地mountain, the top end of the respective hollow pipe and the groundwater level A plurality of nets for filtration are provided at intervals between the lower end and the middle in the hollow pipe, and at least one of the hollow pipes is internally seen so that changes in the surrounding groundwater level can be checked daily. in the possible transparent body, only water directly below or crowded around from the peripheral in inclusive liquefaction energy sediment as the high pressure existing manhole by the earthquake or the like is raised filtered from the lower end of each of the hollow pipe on the groundwater level By then dissipated from the upper end opening overwhelm the liquefaction energy just below the existing manhole, seismic reinforcement method for existing manhole, characterized in that so as to prevent the push-up floating and sinking fluctuations in the existing manhole.

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