JP2006183244A - Constructing structure for preventing thrusting flotation and frost heave of manhole and settlement, crack, waviness and frost heave of backfill soil on main pipe due to earthquake or the like - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the liquefaction of backfill soil due to earthquake or the like, the thrusting floatation and frost heave of a manhole due to freezing expansion, and the crack, waviness and settlement of backfill soil on a main pipe. <P>SOLUTION: In backfill construction of placing a sewage line including the manhole and the main pipe, a liquefaction preventing material formed by mixing a water non-permeable and non-oozing asphalt raw material and an elastic body (a rubber chip) is poured into a drive gap between the manhole and a natural ground and filled therein for backfill. Otherwise, the liquefaction preventing material and gravel or crushed stones are alternately bedded into a plurality of layers for backfill in the condition of embracing the liquefaction preventing material to prevent the flotation and oozing of underground water. This prevents the flotation and frost heave of the manhole resulting from the liquefaction of a backfill portion due to earthquake and from the freezing expansion thereof and prevents the settlement, waviness, crack and frost heave of the backfill soil on the main pipe. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a construction structure for preventing a levitation or frost heaving due to an earthquake in a manhole and a settlement, cracking, waving, frost heaving, etc. of backfill soil on a main pipe.

Conventionally, sewerage work including concrete manholes and mains is often carried out by excavation after the completion of the road. At this time, the backfill work of the excavated part is narrow, so it will be pressed with a lightweight compactor, and traffic regulations Since the construction period is not sufficient due to the shortening of the construction period, it tends to remain unsatisfactory.
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  For this reason, there is a problem that the main line that has been cut and backfilled sinks due to a weight load, and the manhole is pushed up and floated. Especially in soft ground and high groundwater levels, there is a problem that when the ground is repeatedly shaken by an earthquake or the like, the backfill soil liquefies and promotes subsidence or the like to increase the manhole uplift.

  Also, in cold regions, the water in the backfill soil freezes and rises, causing the manhole to rise and float, causing the backfill soil on the main to crack and wave, losing flatness and hindering traffic. There is a problem.

  In addition, a gap between the backfill soil and the manhole and between the natural ground and the backfill soil is created, and groundwater rises from there, and water penetrates into the backfill soil and the shaking is repeated due to earthquakes, etc. If this happens, the backfill soil will be liquefied, causing sedimentation, cracks, etc., causing the manhole to rise and float, causing the main pipe to become uneven.

  In the present invention, a liquefaction prevention material is constituted by mixing an asphalt material having water impermeability and water blocking properties and an elastic body (rubber chips, etc.), and a cut-off portion is formed by pouring and filling the liquefaction prevention material. Backfilling or backfilling with alternate layers of liquefaction prevention material, earth and sand, crushed stone, etc. on condition that it is encapsulated with the liquefaction prevention material, and further eliminating the occurrence of marginal gaps, This problem was solved by preventing the floating and seepage of groundwater.

  As described above, in the backfilling work after the sewerage work including the manhole and the main pipe, the present invention mixes an elastic body (such as rubber chip) with an asphalt material having water impermeability and water blocking ability. Since the liquefaction preventive material is poured and filled, or gravel and crushed stone are covered with the liquefaction preventive material and then backfilled, the groundwater floating is blocked and the groundwater penetrates the backfill soil. Therefore, even if repeated vibrations occur due to earthquakes, the backfill soil is prevented from becoming liquefied and manholes can be prevented from rising and rising due to subsidence or cracks in the backfill soil. The effect of eliminating the freezing of manholes due to the freezing expansion of the backfill soil and the settlement, cracks, and undulations of the backfill soil on the main pipe. There is an effect that the groundwater does not rise from the edge gap.

  In the backfilling work after laying the manhole and main pipe in the cut groove, the present invention mixes an elastic body (such as rubber chip) chopped into an asphalt material into the cut gap between the manhole and the ground. Poured and filled with liquefaction preventive material configured to have water impermeability and water barrier property, or in alternate layers with gravel, crushed stone, asphalt cutting waste material etc. covered with the liquefaction preventive material Fill and backfill. As a result of this backfilling, the rise of groundwater is blocked and moisture permeation is prevented. As a result, even if the vibration is repeated due to earthquakes, the backfilling soil does not liquefy. There will be no levitation lift. In cold regions, the freezing and expansion of water in the backfill soil is eliminated, so that it is possible to prevent traffic troubles due to cracks and undulations in the backfill soil and freezing of manholes.

  Fig. 1 shows an example of backfilling of a manhole 1 part. An elastic body (such as rubber chips) is mixed with an asphalt material having water impermeability and water blocking properties in an opening gap 3 between a manhole 1 and a natural ground 2. The liquefaction preventive material 4 configured in this manner is poured and filled, naturally solidified, and backfilled.

  In the case of the existing manhole 1 instead of new construction, the liquefaction preventing material 4 is directly sprayed and pressed around the manhole 1 using a water jet or the like.

  FIG. 2 shows a case where the excavation gap 3 between the manhole 1 and the natural ground 2 is wide. In this case, the backfilling material 4a such as gravel and crushed stone is wrapped in the liquefaction preventive material 4 in three or four layers. And then backfill it in multiple layers.

  FIG. 3 shows an example in which the liquefaction preventing material 4 is injected around the pile 5 when the pile 5 is driven and fixed under the manhole 1.

  FIG. 4 (a) is an example of backfilling of the cut-out portion 3a on the main pipe 6. Since gravel, crushed stones 4a, etc. are wrapped back in an alternating multiple layer so as to be wrapped in the liquefaction prevention material 4 in accordance with FIG. is there. FIG. 4B is a conventional example, and shows a state in which the backfill soil 7 on the main pipe undulates due to freezing and expansion of water in the backfill soil 7.

  For gravel, crushed stone, etc., it is also possible to recycle asphalt road waste material by room temperature cutting or crushing, or by dividing it by heating.

  As shown in FIG. 5 (a), the liquefaction prevention material 4 is applied to the outer peripheral surface of the manhole 1, and the liquefaction prevention material 4 is poured also into the natural ground 2 in the process of backfilling. As shown in the figure, an edge cut gap 3b is formed between the outer peripheral surface of the manhole 1 and the backfill soil 7, and an edge cut gap 3b is prevented from being formed between the ground 2 and the backfill soil 7. Sometimes.

  FIG. 6 shows an example in which a horizontal overhanging fin 8 (Japanese Patent Application No. 2004-340011) is provided in the manhole 1 to be integrated with the liquefaction prevention material 4.

  As described above, in the backfilling work after sewage laying including the manhole and the main pipe, the present invention uses a liquefaction preventive material, so that there is no seepage of rainwater from the surface, as well as floating of groundwater. Because of the absence of seepage and penetration, liquefaction of backfilling soil is prevented even if earthquakes are repeated, preventing traffic from rising and freezing on manholes and cracking and undulation of backfilling soil on mains. A failure can be prevented.

Side sectional view showing an example in which liquefaction prevention material is poured and filled in the opening gap between the manhole and natural ground This is an example of a wide open-cut gap, and is a side cross-sectional view of gravel, crushed stone, etc., backfilled in multiple layers in the manner of wrapping with liquefaction prevention material Side sectional view showing an example where piles are driven under a manhole (A) is a side sectional view showing an example of backfilling of the cut-out portion on the main pipe, and (b) is a conventional example diagram. (A) is a side sectional view showing an example in which a liquefaction preventive material is applied to the outer peripheral surface of a manhole and a liquefaction preventive material is poured into the natural mountain side to form a concave surface that blocks the floating of groundwater between the manhole and the natural mountain; Longitudinal side view showing an example where a manhole is provided with a horizontal overhang fin and integrated with a liquefaction prevention material

Explanation of symbols

1 is a manhole, 2 is a natural ground, 3 is an excavation gap, 3a is an excavation part on the main pipe, 3b is an edge gap, 4 is an anti-liquefaction material, 4a is gravel, crushed stone, etc., 5 is a pile, 6 is a main pipe, 7 is backfill soil, 8 is Horizontal overhanging fin to prevent manhole levitation

Claims (4)

  In refilling work after laying sewers including manholes and mains, this is a liquid made by mixing an asphalt material and an elastic material (rubber chips, etc.) with water barrier properties and impermeability in the open gaps between manholes and natural ground. Frozen and filled with anti-liquefaction material, or backfilled by alternate multi-layer laying of the liquefaction preventive material and gravel, crushed stone, etc. Prevents seepage and liquefaction due to seismic vibrations in the backfill and prevents manholes from rising and freezing due to freezing and expansion, and prevents backfill soil from sinking, cracking, wavy, frosting, etc. A construction structure that prevents manhole levitation and frost heaving due to earthquakes, etc., as well as sinking, cracking, waving, and frost heaving of backfill soil on the main.   The construction structure according to claim 1, wherein a liquefaction prevention material is applied to the outer wall surface of the manhole, and the liquefaction prevention material is poured into the natural mountain side in the process of backfilling.   The construction structure according to claim 1 or 2, wherein the groundwater is blocked by connecting the area around the manhole and the ground with a liquefaction-preventing material layer to block groundwater.   The construction structure according to any one of claims 1 to 3, wherein a horizontal overhanging fin is provided on an outer wall surface of the manhole to be integrated with the liquefaction prevention material.

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