JP5250660B2 - Manhole and other floating prevention methods - Google Patents

Description

  The present invention is a method for preventing manholes, etc. generated by the liquefaction phenomenon of the ground due to an earthquake from rising from the ground surface, and in particular, it is also applied to existing manholes where measures against the liquefaction phenomenon, etc. are not taken It is related to the levitating prevention method such as manholes.

  Various underground pipes for water supply, sewerage, electricity, gas, communication, etc. are buried in the underground such as roads. Manholes, etc. installed at the connection positions of these pipes are strong enough to withstand earth pressure. Although it is constructed in a heavy structure, it is difficult to expect that the geology is constant and uniform within the range of the buried ground, and the density of the earth and sand filled around the buried structure tends to be uneven. For this reason, manholes are likely to rise due to liquefaction caused by earthquakes, and prevention thereof is an important issue.

  Regarding the ground liquefaction phenomenon, when seismic motion occurs, the state in which the soil particles and soil particles were previously joined together collapses, first the soil particles float in the groundwater, and then the soil particles are caused by gravity. Subsidence, the apparent volume of the ground decreases, and settlement occurs on the ground surface. The subsidence phenomenon increases the pore water pressure between the soil particles, resulting in a rising water flow and further liquefaction of the soil particles in the ground, and the rise of the manhole is said to be caused by the settlement of the ground.

  On the other hand, manholes, etc. are constructed to have a tough weight structure that can withstand earth pressure, but because they are hollow, the apparent specific gravity is lighter than water and buoyancy occurs when liquefaction occurs during an earthquake. The manhole is raised by the lift.

  The fluidization of the ground due to earthquake liquefaction changes the ground into a mud-like liquid with a high specific gravity, and the higher the specific gravity, the lower the force due to the sum of the weight of the manhole, the frictional force of the ground due to horizontal earth pressure, etc. The difference becomes lift and is applied to the manhole. The coefficient of friction between the manhole and the ground decreases with fluidization, so if the downward force becomes smaller than the lift force, the manhole will rise to the ground surface.

  Due to the earthquake motion, the soil particles float in the groundwater and sink due to gravity, and due to the decrease in the apparent volume of the ground and the settlement phenomenon, the pore water pressure rises between the soil particles, resulting in a rising water flow and further liquefaction of the soil particles in the ground. For example, according to the invention of Patent Document 1, a plurality of drain pipes embedded around the manhole are connected to the side through holes of the manhole. It has been practiced to prevent the increase of pore water pressure by flowing water that has entered the drain pipe into the manhole through a connecting pipe.

  Further, since the apparent specific gravity of the manhole is lighter than that of water, a plate that dissipates the pore water pressure on the plate by a binding tool as in Patent Document 2 in response to the occurrence of buoyancy caused by liquefaction and the rise of the manhole. Is connected to the manhole, and the floating is prevented by the weight of the binding tool and the weight of the roadbed and pavement surface material on the plate, or for roadbed material support horizontally from a position higher than the average annual maximum groundwater level as in Patent Document 3. Attempts have also been made to extend a floor board and to lay a stabilized roadbed material on the floor board.

  Further, the invention of Patent Document 4 proposes that a hole communicating between the underground and the manhole is opened, and that a check valve that allows the inflow of water from the underground into the manhole and blocks the outflow is set in the hole. There is also. On the other hand, using the construction method described in Patent Document 5, a method of injecting and hardening a ground hardening material to the outer periphery of the manhole without causing a water stream that generates liquefaction to flow into the manhole is performed in the name of the ESP construction method. Yes.

In this construction method, the double pipe of the outer pipe and the inner pipe by the strainer is discharged from below and inserted into the ground around the manhole, and only the inner pipe is lifted up to the packer part through the strainer hole of the outer pipe. A quick setting injection is performed, the packer portion is stepped down to inject a loose binding material, the injection double tube is removed, and the outer periphery of the manhole is solidified by an injection hardened layer.
JP 2006-214242 A JP 2010-24751 A JP 2007-169927 A JP 2006-124966 A JP-A-9-88056

  In any of the methods described in Patent Documents 1 to 4, the outer periphery of the manhole is supported by a physical structure, and a water flow that generates liquefaction is caused to flow into the manhole to prevent the manhole from rising. In addition to excavation of the ground around the manhole, it is necessary to construct a support body in the manhole or to form an introduction hole for flowing water into the manhole structure. There is a problem that it can not be handled.

  The method of injecting and hardening the ground hardening material to the outer periphery of the manhole using the construction method described in Patent Document 5 does not require excavation of the manhole surrounding ground or large-scale construction as described above, and can also be applied to existing manholes. However, the injection of the hardener is an indirect one that relies on the osmotic pressure of the hardener liquid through the strainer tube, and since the hardened hardener is used except for the packer part, it takes a very long time for the injection to solidify. Cost.

  Also, as the injection rod, a strainer outer tube provided with a large number of peripheral surface discharge holes, and a discharge hole closely slidably fitted so as to close the peripheral surface discharge holes of the outer tube from the inside are provided. Consists of an inner pipe, and the inner pipe slides into the outer pipe for injection, while the injection pressure is a low pressure close to natural pressure. However, there is also a problem that the injection hardened material layer becomes dense and lacks stability.

  The present invention is intended to address the above-described problems, and an injection rod having a side injection nozzle on the distal end side wall is inserted into the manhole outer periphery ground to the depth of the bottom of the manhole structure, and the ground hardening material is laterally provided. Rotating and rising at 5 to 6 Rpm while spraying, or forming a cylindrical hardened layer by rotating and lowering to the bottom of the manhole structure while feeding the ground hardened material to the injection rod. The manhole outer periphery ground was consolidated by paralleling the manhole outer periphery.

  Also, a plurality of injection rods are inserted adjacently in parallel within the jet contact distance, and at the bottom of the manhole structure, the ground is rotated and raised simultaneously so that the rotation directions of the adjacent injection rods are opposite to each other. The hardener was sprayed, and the hardener jet flow from each injection rod crossed in the opposite direction to stir and mix the hardener and soil particles to form a hardener injection layer with high mixing density.

  In other words, the burial depth of the manhole structure is about 5 to 6 meters, and since the ground cannot absorb the high pressure injection pressure, the osmotic injection by the strainer is adopted. While the hardening material flows into the part, the hardening material does not enter the compacted ground layer, and a fragile hardened layer that is sparse and dense is formed.

  In the present invention, the curing material is injected and injected from the side injection nozzle at an injection pressure of 0.5 to 4 Mpa, thereby giving direction to the injected hardening material and rotating the rod to the soil of the target ground. A hardened layer having a high mixing density and balanced by cutting and stirring with a jet is created.

  In addition, since the curing material is injected and injected at an injection pressure of 0.5 to 4 Mpa, by adjusting the injection pressure by adjusting the strength, the strength of the curing material jet that contacts the outer periphery of the manhole structure is increased and cured. A gripping force due to the concavo-convex structure can be given to the contact surface portion between the material layer and the outer periphery of the manhole structure to increase the bonding force between the cured material layer and the outer periphery of the manhole structure.

  Further, a plurality of injection rods are inserted adjacently in parallel within the jet contact distance, and the injection of the hardened material is injected by simultaneously rotating and increasing the rotation directions of the adjacent injection rods so as to be opposite to each other. The flow was mixed in the opposite direction so that the hardener and the soil particles were stirred and mixed to enhance mixing.

  The hardened material layer formed in this way differs from the infiltrated layer by infiltration with a strainer that does not have an intentional shape base, so that the rod is centered by the cutting force by the pressure-injected hardened material and the stirring force by the rotation of the rod. It is formed in a specific shape based on a cylindrical shape, so if it is surrounded by surrounding the manhole structure in parallel, it will be stronger than simply preventing soil particles from flowing by ground consolidation. It can cope with ground liquefaction even as a high protective wall.

  Since the present invention is configured as described above, it is possible to set up a structure that prevents the manhole structure from rising due to ground excavation or large-scale construction, or to introduce a water flow for flowing a liquefied water flow into the manhole. Since it can be constructed by inserting a single-tube injection rod around the manhole structure without making a hole in the manhole, it can be used as a retroactive response to an existing manhole.

  In addition, since the hardening material is injected by pressure injection from the side nozzle, there are obstacles such as the bottom of the manhole structure and the lower part of the drain pipe extending from the manhole to the side, and the material is injected vertically from the ground surface. It is possible to inject even into areas where it is not possible to protect the entire area around the manhole.

  In addition, it can be easily constructed with a single-tube structure injection rod, and in addition to a slow-curing hardener, a quick-curing hardener can be used, greatly saving time and labor, and stirring. A well-balanced ground hardened layer can be created by mixing, not only suppressing the fluidity of soil particles by consolidation, but also the ground hardened layer can actively respond to earthquakes etc. as a tough structure with supportive force Is.

The longitudinal cross-sectional side view of the manhole embedding ground which shows the Example of this invention and shows the state which inserted the injection rod into the outer peripheral both sides of a manhole structure Similarly, an overall side view of the device and a part of the target ground showing a construction-like flaw that is injected with a hardening material while rotating an injection rod inserted into the outer peripheral side of the manhole structure. Similarly, a construction image plan view showing a rod with a cylindrical hardened layer formed in parallel on the outer periphery of the manhole structure Similarly, a vertical cross-sectional side view of the manhole buried ground showing the state that the ground hardened layer was created on the outer periphery ground of the manhole structure Similarly, an enlarged perspective view of the tip of the injection rod showing the hardened material injection-like flaw from the side injection nozzle of the injection rod inserted into the outer peripheral side of the manhole structure

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Reference numeral 1 denotes a main body of a manhole structure. A sheet pile or the like is driven into the ground G from the ground surface to excavate a vertical hole for manhole installation, a base 11 is formed on the bottom thereof, a bottom plate 1a is provided, and a pipe is formed on the bottom plate 1a. An attachment block 1b is provided, and underground buried pipes 12 such as sewer pipes are connected to and communicated with at both ends thereof.

  The manhole body 1 is constructed by stacking one or a plurality of cylindrical body blocks 1c on the upper part of the tube mounting wall cylinder 1b, and further stacking a lower inclined wall block 1d having one side inclined in a tapered shape, The lower adjustment block 1e, the upper inclined wall block 1f, and the upper adjustment block 1g are sequentially stacked on top of each other, joined with cement mortar or the like, and further provided with a lid attachment frame 1h and fitted with a lid 1i.

  In general manholes, earth and sand discharged when excavating the vertical hole are often used for backfilling, and a covering is provided so that the upper surface of the lid 1i coincides with the ground GL. Since it is provided for the connection of the underground buried pipe 2 itself, it is set at the connection point.

  The injection rod 3 which is inserted into the manhole outer periphery ground and injects the hardened material is equipped with a monitor part equipped with a digging blade 31 at the tip and one or a plurality of side injection nozzles 32 on the side wall, and can be extended and joined by a joint mechanism. Composed of a single tube rod.

  The rear end of the rod 3 is connected via a swivel 33 to a hardener supply hose 34 that communicates with a hardener plant (not shown), through which a slurry-like hardener prepared and supplied in the hardener plant is received. It is pumped to the opening of the side spray nozzle 32 by the hardened material pumping flow path in the rod, and sprayed in the horizontal direction in the target ground from the nozzle.

  The injection rod 3 is a single tube having a diameter of 40.5 mm, and is inserted in the manhole outer periphery to a depth of about 5 to 6 meters, where the manhole structure is buried, and the ground hardening material is supplied from the side injection nozzle 32 at 10 liter / min. Rotating and rising at 5 to 6 Rpm while spraying at a discharge amount of 0.5 to 4 Mpa, or rotating and descending to the bottom of the manhole structure while pumping ground hardening material to the injection rod The layer W is formed, and the columnar hardened layer W is juxtaposed with the manhole outer periphery to solidify the manhole outer periphery ground.

  Example 1 was constructed in an existing manhole in a place where the groundwater level was relatively high. Water glass (instantaneous hardening) was applied from the side injection nozzle 32 to a ground part separated from the outer periphery of the manhole body 1 by about 300 mm. The injection rod 3 is rotated at a high speed while being ejected at a discharge rate of 10 liters / min and inserted downward to the manhole structure embedding depth, and the injection material from the nozzle 32 is cement slurry (fast-curing hardening material B). The liquid was changed to (Liquid), and the rotation amount was increased at 5 to 6 Rpm while ejecting at a discharge amount of 10 liters / min and an injection pressure of 3 Mpa.

  By doing so, the water glass injected and injected into the surrounding soil at the time of descending insertion acts as a lubricating liquid that reduces the rotational torque of the rod 3 and is stirred and mixed by the cement slurry jet that is pressure-injected when the rod rotates upward. Then, it can react and give a caking effect with a short gel time.

  Example 2 was applied to an existing manhole installed on soft ground with a high N value. The surface of the manhole was covered with an iron plate and the surface was packed, and the manhole body 1 was separated from the outer periphery by about 500 mm. The injection rod 3 is rotated at 5 to 6 Rpm while the one-part flash hardening material is ejected from the side injection nozzle 32 at a discharge amount of 10 liter / min. Then, the rod is removed, and the hardened material is injected into the surrounding soil of the rotation descending trajectory of the rod to form a hardened layer W, which is juxtaposed to solidify the surrounding soil of the manhole.

  In this embodiment, a one-component instantaneous hardener is used, and the overflow of the hardener is packed by laying an iron plate or the like, and the injection rod 3 is rotated and lowered while spraying the hardener at once. Since the hardening material is injected, the work can be performed in a short time. However, it is difficult to remove the rod unless the rod is immediately removed after the completion of the injection.

  In the third embodiment, the injection pressure at the time of injection injection of the hardener is switched and adjusted to change the impulsive pressure at the front end of the hardener jet impinging on the outer peripheral surface of the manhole body 1, and the hardened layer W and the outer peripheral surface of the manhole main body 1 are changed. The contact surface is made uneven to increase the frictional force between the ground and the manhole body 1 to enhance the unity between the ground and the manhole.

  In this embodiment, the injection rod 1 may be inserted into the target ground in any manner. For example, the injection pressure of the hardened material is alternately switched from 2 Mpa to 5 Mpa at a predetermined interval of the injection rod lifting. By injecting, the contact friction between the hardened layer W and the outer peripheral surface of the manhole body is increased, and the adhesion between the manhole and the buried ground is strengthened.

  In addition, by adjusting the injection pressure and adjusting the ejection amount of the curing material, it is possible to provide a variety of consolidation of the cured layer W, and to cope with a complicated shape in which the diameter of the manhole body 1 changes. In addition, it is possible to avoid the injection into an extra portion and to save the curing material.

  Furthermore, by adjusting the injection pressure and the discharge amount of the hardener while measuring the internal pressure in the hardened layer W and balancing the internal pressure by attaching a ground pressure measuring mechanism to the monitor portion of the injection rod 1, A balanced consolidation layer surrounding the manhole structure can be created.

  The manhole ascent prevention method according to the present invention protects manholes from earthquakes and ground liquefaction, which is an extremely important mechanism for maintaining joints in underground pipes similar to blood vessels in modern industries. Small-scale construction can provide a certain effect and can be applied to maintenance of existing manholes, so the industrial utility value is extremely high.

DESCRIPTION OF SYMBOLS 1 Manhole body 11 Manhole installation base 1a Manhole body bottom plate 1b Manhole body tube mounting block 1c Manhole body trunk block 1d Manhole body lower inclined wall block 1e Manhole body lower adjustment block 1f Manhole body upper inclination Wall block 1g Manhole body upper adjustment block 1h Manhole body lid mounting frame 1i Manhole body lid 2 Underground pipe 3 Hardened material injection rod 31 Excavation blade 32 at the tip of injection rod Side injection nozzle 33 at the tip of monitor unit After injection rod End swivel 34 Hardener supply hose 35 to injection rod Drive mechanism G of injection rod Manhole installation ground W Formation hardening layer

Claims (4)

  An injection rod having one or more side injection nozzles on the side wall of the tip is inserted to the ground part separated from the outer peripheral edge of the manhole body by a predetermined distance to the manhole body embedding depth, and the ground hardening material is inserted from the side injection nozzle. Rotating and raising the injection rod while spraying pressure to form a columnar hardened layer by injecting ground hardener, and building the columnar hardened layer in parallel with the outer periphery of the manhole body Construction method   Packing treatment is performed on the ground surface from the ground part separated from the outer periphery of the manhole body by a predetermined distance, and the injection rod is rotated down to the manhole body embedding depth while pressure-injecting the ground hardening material from the side injection nozzle to inject the injection rod. The manhole and the like levitating prevention method according to claim 1, wherein after the ground hardening material is injected into the surrounding soil, the injection rod is removed to form a cylindrical hardened layer.   The injection rod is rotated and lowered to the manhole body embedding depth while pressure-injecting the liquid A of quick setting hardener, and the injection rod is rotated up from the same point by switching the pressure injection hardener to liquid B of the quick setting hardener. The manhole or the like levitating prevention method according to claim 1, wherein a cylindrical hardened layer is formed by injecting an instantaneous hardened ground hardening material.   At the time of injection injection of the hardener, the impact at the tip of the hardener jet that contacts the outer peripheral surface of the manhole body by switching and adjusting the injection pressure and / or the discharge amount of the hardener according to the ground pressure or the change in the shape of the manhole body. The manhole levitating prevention construction method according to claim 1, claim 2 or claim 3 configured to change the pressure.

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