JP5535581B2 - Prevention method of rising and sinking of existing manhole - Google Patents

Description

  The present invention relates to a method for preventing the rising and sinking of existing manholes.

  The manhole is an underground structure installed on the ground to enter and exit the sewer pipes and other caverns that contain electrical and communication cables. Manholes have a low specific gravity because they are hollow. For this reason, when the surrounding ground is a sand layer and the groundwater level is high, the surrounding ground is liquefied during an earthquake, resulting in buoyancy exceeding its own weight, and manholes are floating on the ground.

  As a method to prevent the existing manhole from rising and sinking, drill holes from the bottom of the manhole to the non-liquefied layer, lower the anchor into the hole and fix it in the non-liquefied layer, and fill the surrounding ground and around the anchor with solidified material How to do is known.

  For example, in Utility Model Registration No. 3148230 (Patent Document 1), a bottom plate is stenciled with a stencil bolt from a manhole opening on a road, and the soil is further squeezed with a double pipe to form a non-liquefaction layer. A method is described in which an anchor is constructed by putting it to a predetermined depth and injecting a solidified material around the bolt. Specifically, “The liquefied layer is constricted on the cast-in-place concrete bottom plate of the sewer manhole, through the bottom plate and the bottom plate with a squeezed bolt from a symmetrical position across the sewer, and the outer pipe prevents the soil from collapsing. After forming the hole and further constricting it to the predetermined depth of the non-liquefaction layer, leaving the constriction bolt, forming a pile-shaped anchor by injecting the solidified material while pulling out the outer tube, the top of the constriction bolt is the place The structure for preventing the manhole from rising during an earthquake characterized by being fixed with a washer and a nut on the upper surface of the bottom of the cast concrete (claim 1) is described.

  In Japanese Patent Application Laid-Open No. 2005-24896 (Patent Document 2), a step of hanging invert concrete placed at the bottom of a manhole, a step of drilling from the bottom of the manhole to a non-liquefied layer, and the drilling The anchor tension material is inserted into the hole, the grout is injected, and the tip of the anchor tension material is fixed to the non-liquefied layer, and the upper end of the anchor tension material protrudes from the opening provided in the center. A step of disposing a pressure receiving plate at the bottom of the manhole, a step of fixing an upper end of the anchor tensile member to the pressure receiving plate, a step of covering the upper end of the anchor tensile member with a cap, and a bottom of the manhole The method for preventing the manhole from rising due to liquefaction is characterized in that it includes a step of placing invert concrete.

  On the other hand, although it is not an invention related to manhole anchors, Japanese Patent Application Laid-Open No. 10-46574 (Patent Document 3) aims to make it possible to “completely perform construction in any soft geology” (paragraph 0017). Further, inventions relating to anchors used for planting underground struts, etc., in addition to temporary piles of orchard fences, temporary houses at the time of disaster recovery, are disclosed. This document describes a stay anchor having two spreading plates, each curved outward, at the tip (FIG. 4). When this stay anchor is placed on the excavated hole bottom and an impact is applied from above, the two spread plates enter the side wall of the hole while further curving outward. Thereby, the strong resistance with respect to an uplifting load is obtained.

Utility Model Registration No. 3148230 JP 2005-24896 A JP 10-46574 A

  In the conventional manhole lifting prevention method, there is room for improvement in the adhesion between the anchor and the non-liquefied layer. There is also room for shortening the construction period. Therefore, the main object of the present invention is to provide a manhole levitation prevention method that can reinforce the anchoring force between the anchor and the non-liquefied layer. Another object of the present invention is to provide a manhole levitation prevention method that can be constructed in a shorter time.

  The present inventor has intensively studied to solve the above problems, and by applying the stay anchor as described in Patent Document 3 described above, the fixing force between the stay anchor and the non-liquefied layer is enhanced, It was found that it is effective in preventing the manhole from rising and sinking. Moreover, it discovered that a construction period could be shortened by applying this.

The present invention in one aspect which has completed the findings as a basis, through the bottom plate of the existing manhole, step 1 of boring to non liquefaction layer, tube-like that having a plurality of resistance members can be unfolded into a lower end Step 2 in which the stay anchor is inserted into the drilled hole, and the resistance member is expanded by applying an impact downward to the resistance member, and the resistance member enters the bottom wall and / or side wall of the hole. The step 3 of filling, the step 4 of filling the drilled hole with cement containing at least one cement hardener selected from aluminate, alkali metal salt and calcium aluminate, upper only contains a step 5 for fixing the bottom plate of the manhole, the resistance member has a hole for the passage of the cement, a floating sinking prevention method of the existing manhole.

  In another embodiment of the manhole levitation prevention method according to the present invention, step 1 ′ is performed between step 1 and step 2 in which an anchor support bar having a horizontal plate at the lower end is inserted into the drilled hole. Step 2 is performed by passing a tubular stay anchor through the anchor support bar.

  In still another embodiment of the manhole levitation prevention method according to the present invention, step 1 is performed by double pipe excavation and the process is performed up to step 5 without pulling out the outer tube.

  In still another embodiment of the manhole levitation prevention method according to the present invention, the step 4 includes the step of filling the bottom of the drilled hole with a cement paste, and then mixing the aggregate with the cement paste. It consists of a step of filling mortar or concrete into the remainder of the drilled hole.

In yet another embodiment of the manhole levitation prevention method according to the present invention, the bottom of a hole drilled with cement injected through a tubular stay anchor is filled, and the space between the stay anchor and the drilled hole is filled. Step 4 is performed by filling the remainder of the hole drilled with cement injected from the void.

  In still another embodiment of the manhole levitation prevention method according to the present invention, the tip of the resistance member has an acute angle.

  According to the present invention, the anchoring force between the anchor and the non-liquefied layer is strengthened, which is effective in preventing the existing manhole from rising and sinking. Moreover, this invention can also contribute to shortening of a construction period.

FIG. 1 is a schematic view showing a state when drilling from a bottom plate of a manhole to a non-liquefied layer. FIG. 2 is a schematic diagram showing a state when the stay anchor is inserted into the drilled hole. FIG. 3 is a schematic view showing a state when an impact is applied to the stay anchor and the resistance member enters the wall surface of the drilled hole. FIG. 4 is a schematic diagram showing a state in which the drilled hole is filled with cement. FIG. 5 is a schematic view showing a state in which a tubular stay anchor is inserted into an anchor support bar. FIG. 6 is a schematic view when the lower part of the stay anchor is viewed from the lateral direction. FIG. 7 is a schematic view when the stay anchor is viewed from above. FIG. 8 is a schematic diagram showing a state when the driving pipe is fitted into the stay anchor. FIG. 9 is a schematic diagram showing a state when the upper end of the stay anchor is fixed to the manhole.

  Hereinafter, the form for implementing this invention is explained in full detail, referring to FIGS. 1-9 for a sewer manhole as an example.

<Step 1>
In step 1, the bottom plate 12 of the manhole 11 is penetrated to the non-liquefied layer 13 (see FIG. 1). As a specific procedure, after stopping the sewage flowing into the manhole, the bottom plate (invert concrete) of the manhole is penetrated by a drilling machine, and then drilled to the non-liquefied layer. The diameter of the drilled hole 16 is large enough to insert the stay anchor. The number of holes to be drilled may be set as appropriate in consideration of the intended effect of preventing the floating and sinking. The position of the hole to be drilled may be appropriately set so that the load on the bottom plate of the manhole is not biased while taking into account the position of the sewer pipe. For example, one place can be provided in the center of the bottom plate of the manhole, or two places can be provided at symmetrical positions with the sewer pipe interposed therebetween.

  As the drilling method, either single pipe digging or double pipe digging may be used, but in places where liquefaction is a problem, the ground is weak with a sand layer, and the drilled hole wall is often difficult to stand by itself. In addition, since the depth to the non-liquefied layer may be considerably deep, it is preferable to drill with a double pipe in order to prevent the outer wall from collapsing the hole wall. When drilling by double pipe digging, the outer pipe is pulled out so that the cement and the surrounding ground are more firmly fixed. However, in the present invention, the anchoring effect by the stay anchor is high, so that sufficient manhole levitation can be achieved without pulling out the outer pipe. Preventive effect is obtained. In this case, the labor for pulling out the outer tube can be saved, so that the construction period can be shortened.

<Process 2>
In step 2, a rod-like or tubular stay anchor 22 having a plurality of expandable resistance members 21 at the lower end is inserted into the drilled hole (see FIG. 2). The length of the central axis of the stay anchor is selected according to the embedding depth so that the upper end can be fixed to the manhole bottom plate later. The material of the stay anchor is generally made of metal in order to ensure sufficient strength not to be defeated by the ground, but is not particularly limited. The number of resistance members is two or more in order to strengthen the fixation to the non-liquefied layer. In that case, in order for the stay anchor to be stably fixed, it is desirable that the resistance members have the same shape, and it is desirable that the stay members be arranged at equal intervals or symmetrically around the central axis of the stay anchor. The shape of the resistance member is not particularly limited as long as it can enter the bottom wall and / or side wall of the hole while expanding and give resistance to the rise and fall of the manhole in the next process. Or it can be set as the curved shape curved outward (refer FIG. 6). The overall shape may be a plate shape, a square shape, a rod shape, or the like. FIG. 7 shows an example of a plate-like resistance member. In that case, it is preferable to make the tip 71 of the resistance member an acute angle in plan view in order to facilitate entry into the non-liquefied layer. The length of the resistance member in the traveling direction is adjusted as appropriate so that the resistance member can sufficiently enter the non-liquefied layer and the stay anchor can be firmly fixed to the non-liquefied layer.

The central shaft portion of the stay anchor may be rod-shaped, but it is advantageous because cement can be fed from this tube by making it tubular. As will be described later, since cement can be poured into the bottom of the hole that has been drilled without being obstructed by the resistance member, the resistance to the rise and sink of the manhole is enhanced. In the present invention, the stay anchor is tubular.

  In the form in which the central axis of the stay anchor is tubular, step 1 ′ can be performed between step 1 and step 2 in which an anchor support bar 51 having a horizontal plate at the lower end is inserted into the drilled hole. The shape of the horizontal plate is not particularly limited, and can be various polygonal shapes, but is typically a disc shape. By inserting the anchor support bar, it becomes possible to resist the under pressure load, which helps to prevent the manhole from sinking. After the anchor support bar is inserted, the stay anchor is tubular, so that step 2 can be performed by passing through the anchor support bar (see FIG. 5). The resistance member has a higher anchoring effect when it penetrates into the side wall surface than the bottom wall surface of the drilled hole. However, by installing the anchor support bar, the resistance plate is attached to the lower end of the stay anchor. There is also an advantage that it helps to expand and easily enters the side wall surface of the drilled hole.

<Step 3>
In step 3, the resistance member is further expanded by applying an impact to the resistance member, and the resistance member enters the bottom wall and / or the side wall of the hole (see FIG. 3). Thereby, the anchoring effect by a stay anchor is exhibited and the adhering force of a stay anchor and a non-liquefaction layer can be raised simply. Although there is no restriction | limiting in particular as a method of applying an impact toward the downward direction to a resistance member, The method of hit | damaging the upper end of a stay anchor toward the downward direction is mentioned. A receiving surface 81 may be provided at the upper end of the resistance member, and the driving pipe 82 may be fitted outside the stay anchor to hit the driving pipe (see FIG. 8).

<Step 4>
In step 4, the drilled hole is filled with cement 41 (see FIG. 4). This can be done by gradually pouring cement into the gap between the stay anchor and the drilled hole. At this time, since the resistance member blocks the flow of cement, it is difficult for the cement to reach below the resistance member. Therefore, it is preferable to make the stay anchor into a tubular shape, flow cement into the pipe, and inject it into the hole bottom from the lower end of the pipe (see the arrow on the lower side of FIG. 3). As a result, the cement can sufficiently reach below the resistance member. What is necessary is just to inject | pour cement into the remainder of a hole from the space | gap between a stay anchor and the drilled hole (refer the upper arrow of FIG. 3). The order of injecting cement from both directions is not particularly limited. Accordingly, in a preferred embodiment of the present invention, the stay anchor is tubular, filled in the bottom of the hole drilled with cement injected through the stay anchor, and injected from the gap between the stay anchor and the drilled hole. Step 4 is carried out by filling the remainder of the holes drilled with cement.

As another method for reaching the cement below the resistance member, the bottom of the drilled hole is filled with cement paste, and then the mortar or concrete with the aggregate mixed in the cement paste is drilled. There is a method of filling the remainder. The specific procedure is to pour a low-viscosity cement paste through the gap between the resistance member and the drilled hole and reach the bottom of the hole. Fill the remainder of the drilled hole with mortar or concrete that has a higher viscosity than the paste.
By switching the cement viscosity in this way, it is possible to shorten the work period while filling the hole in which the cement has been drilled without gaps. By providing a hole 72 for the cement to pass through the resistance member, the cement may be filled below the resistance member (see FIG. 7).
In the present invention, cement paste, mortar and concrete are included in the concept of cement.

  Although there is no restriction | limiting in particular as a cement used by this invention, Usually, various portland cements, such as early strength, super early strength, low heat, and moderate heat, these portland cements mixed blast furnace slag, fly ash, or silica. Various mixed cements, filler cements mixed with limestone powder and blast furnace slow-cooled slag fine powders, environmentally friendly cements made from various industrial wastes as main raw materials, so-called eco-cement, etc. You may use individually and may mix and use 2 or more types. Furthermore, it is also possible to use a pulverized product thereof.

  By adding a cement hardener to the cement and accelerating the hardening of the cement, construction can be performed in a short time.

  It is desirable from the viewpoint of shortening the construction period that the cement rapid hardening material contains at least one kind of cement rapid hardening material selected from aluminate, alkali metal salt and calcium aluminate. Among these, calcium aluminates are preferable in terms of excellent setting properties of cement concrete and good strength development. Examples of the aluminate include alkali metal or alkaline earth metal aluminates such as sodium aluminate, potassium aluminate, calcium aluminate, and magnesium aluminate. Examples of the alkali metal salt include sodium chloride, potassium chloride, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate. Calcium aluminates include calcium aluminate, calcium aluminosilicate, calcium sulfoaluminate, calcium aluminoferrite, and the like.

Calcium Examples of aluminate, for _{example, CaO · 2Al 2 O 3,} CaO · Al 2 O 3, 12CaO · 7Al 2 O 3, 11CaO · 7Al 2 O 3 · CaF 2, 3CaO · 3Al 2 O 3 · CaSO Examples thereof include crystalline calcium aluminates represented as _{4 and the} like, and amorphous compounds mainly composed of CaO and Al ₂ O ₃ components.

When calcium aluminate is obtained industrially, impurities may be contained. Specific examples _{thereof, SiO 2, Fe 2 O 3} , MgO, TiO 2, MnO, Na 2 O, K 2 O, Li 2 O, S, P 2 O 5, and F is and the like, The presence of these impurities is not particularly problematic as long as the object of the present invention is not substantially impaired. Specifically, there is no particular problem if the total of these impurities is in the range of 10% or less.

  Various commonly used additives can be added to the cement. For example, gypsum, a nitrogen gas foaming substance, a setting regulator, an aggregate, and a water reducing agent can be appropriately added.

  The gypsum is a generic term for each gypsum of anhydrous, semi-water, or dihydrate, and is not particularly limited.

Nitrogen gas foaming substances contain compounds that generate nitrogen gas by reaction with the alkali generated when cement is mixed with water, and gases such as carbon monoxide, carbon dioxide, and ammonia are by-produced. May be. Nitrogen gas foam material can be used to prevent subsidence and shrinkage of cement concrete that has not yet solidified, and to improve resistance to cracking when placed in a dry state. It is not particularly limited.
Specific examples thereof include one or more selected from the group consisting of azo compounds, nitroso compounds, and hydrazine derivatives.

  The setting modifier is not particularly limited, and examples thereof include oxycarboxylic acids, or salts thereof, and carbonates. These may be used alone or in combination of two or more. May be used.

Aggregates include fine aggregates and coarse aggregates.
The fine aggregate is not particularly limited. For example, in addition to river sand, mountain sand, and sea sand, silica sand-based fine aggregate, limestone-based fine aggregate, blast furnace granulated slag-based fine aggregate, and recycled bone It is preferable to select a silica sand-based fine aggregate from the viewpoint of acid resistance and the like.
The coarse aggregate is not particularly limited, and is stipulated in JIS A 5011-1, JIS A 501-2, JIS A 5011-3, and JIS A 5011-4 in addition to crushed stones defined in JIS A 5005. Slag aggregates, commonly known jade gravel and bean gravel can also be used.

Water reducing agents are used to improve fluidity. The water reducing agent used in the present invention is not particularly limited, and examples thereof include naphthalene water reducing agents, melamine water reducing agents, aminosulfonic acid water reducing agents, and polycarboxylic acid water reducing agents. Two or more types can be used.
As specific examples, as a naphthalene-based water reducing agent, a product name “Leo Build SP-9 Series” manufactured by NMB Co., Ltd., a product name “Mighty 2000 Series” manufactured by Kao Corporation, and a product name “Sunflow HS-100” manufactured by Nippon Paper Industries Co., Ltd. Examples of the melamine water reducing agent include the product name “SECAMENT 1000 Series” manufactured by Nippon Sika Co., Ltd. and the product name “Sunflow HS-40” manufactured by Nippon Paper Industries Co., Ltd., and Fujisawa as the aminosulfonic acid type water reducing agent. The product name “Palic FP-200 Series” manufactured by Yakuhin Kogyo Co., Ltd., and the like, and as a polycarboxylic acid-based water reducing agent, the product name “Leo Build SP-8 Series” manufactured by NMB, and the product name “Darex Super 100PHX” manufactured by Grace Chemicals, Inc. ", And trade names" Tupole HP-8 Series "and" Tupole "manufactured by Takemoto Yushi Co., Ltd. P-11 Series "and the like.
Some water reducing agents are in powder form. Specifically, as a naphthalene-based water reducing agent, trade name “Mighty 100” manufactured by Kao Corporation, product name “Sanyo Reberon P” manufactured by Sanyo Chemical Industries, Ltd., and product name “Cell Flow 110P” manufactured by Daiichi Kogyo Seiyaku Co., Ltd. In addition, as a melamine-based water reducing agent, “Melment F10M” manufactured by BASF Pozzolith, and as a polycarboxylic acid-based water reducing agent, for example, trade name “Quinflow 750” manufactured by Mitsubishi Kasei Co., Ltd. and products manufactured by Kao Corporation. The name “CAD9000P” can be used.

<Step 5>
In step 5, the upper end of the stay anchor is fixed to the bottom plate of the manhole. Although there is no restriction | limiting in particular as a fixing means, For example, a threading process can be given to the upper end of a stay anchor, and it can fix to a baseplate with a washer 91 and a nut 92. The upper end of the stay anchor can be covered with a corrosion-resistant cap 93 to prevent corrosion (see FIG. 9).

11 Manhole 12 Bottom plate 13 Non-liquefied layer 14 Manhole cover 15 Sewage pipe 16 Drilled hole 21 Resistance member 22 Stay anchor 41 Cement 51 Anchor support rod 71 Resistance member tip 72 Resistance member hole 81 Resistance member receiving surface 82 Driving pipe 91 Washer 92 Nut 93 Cap

Claims (6)

Through the bottom plate of the existing manhole, step 1 of boring to non liquefaction layer, and step 2 to be inserted into the hole was drilled tube-shaped stay anchor that having a plurality of resistance members can be unfolded into a lower end The step of expanding the resistance member by applying an impact downward to the resistance member to cause the resistance member to enter the bottom wall and / or the side wall of the hole, and the aluminate in the drilled hole , viewed including the step 4 of filling the cement contains at least one cement fast hard material selected from alkali metal salts and calcium aluminates, and a step 5 for fixing the upper end of the stay anchor to the bottom plate of the manhole ,
A method for preventing an existing manhole from rising and sinking , wherein the resistance member has a hole for allowing cement to pass therethrough .   Between Step 1 and Step 2, Step 1 ′ is performed in which an anchor support bar having a horizontal plate at the lower end is inserted into the drilled hole, and Step 2 is inserted into the anchor support bar. The method according to claim 1, wherein the existing manhole is prevented from rising and sinking. The method according to claim 1 or 2, wherein step 1 is performed by double pipe excavation, and step 5 is performed without pulling out the outer tube. 2. The process 4 comprises a step of filling a cement paste at the bottom of the drilled hole, and a step of filling the remainder of the drilled hole with mortar or concrete mixed with aggregate in the cement paste. The method for preventing levitation and settlement of an existing manhole according to any one of to 3 . Filling the bottom of the hole drilled with cement injected through the tubular stay anchor and filling the remainder of the hole drilled with cement injected from the gap between the stay anchor and the drilled hole 5. The method for preventing the rising and sinking of an existing manhole according to any one of claims 1 to 4 , wherein 4 is implemented. The method for preventing the floating and sinking of an existing manhole according to any one of claims 1 to 5 , wherein the tip of the resistance member has an acute angle.

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