JP5882143B2 - Anti-floating pile for underground structures and anti-floating method for underground structures - Google Patents
Anti-floating pile for underground structures and anti-floating method for underground structures Download PDFInfo
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Description
本発明は、地下構造物の浮上防止杭及び地下構造物の浮上防止工法に関する。
なお、本願明細書でいう「地下構造物」とは、下水道におけるマンホール，汚水桝、電力・通信における地下施設機器や地下ケーブル等を保護する共同溝，上水道やガス配管における路面下の埋設導管及びその付属機器を保護するボックス等を総称する。
The present invention relates to a floating prevention pile for an underground structure and a floating prevention method for the underground structure.
As used herein, “underground structure” refers to manholes in sewers, sewage dredges, underground ditches that protect underground facilities equipment and cables in power and communications, buried conduits under the road surface in waterworks and gas pipes, and A box or the like that protects the accessory device is generically named.
下水道におけるマンホール等の地下構造物は内部が空洞になっているために比重が小さい。このため、周辺の地盤が砂層で、地下水位が高い場合等には、地震時に周囲の地盤が液状化して自重を上回る浮力が生じ、地下構造物が地上に浮き上がってくるという問題が生じる。 Subsurface structures such as manholes in sewers have a low specific gravity because they are hollow inside. For this reason, when the surrounding ground is a sand layer and the groundwater level is high, the surrounding ground is liquefied at the time of an earthquake, resulting in a buoyancy exceeding its own weight, and the underground structure is raised above the ground.
このような現象を防止するため、種々の対策が検討されている（例えば特許文献１〜３参照）。 In order to prevent such a phenomenon, various countermeasures have been studied (for example, refer to Patent Documents 1 to 3).
特許文献１には、既設マンホールのインバート部の周辺棚部を利用し、棚部を貫通して下端を地山に到達させ、上端を地下水位以上とする中空パイプを設け、液状化エネルギー中の水分を中空パイプによりろ過上昇させて放散するようにした既設マンホールの耐震補強方法が記載されている。 Patent Document 1 uses a peripheral shelf portion of an inverted portion of an existing manhole, provides a hollow pipe that penetrates the shelf portion and has a lower end reaching a natural ground, and has an upper end equal to or higher than the groundwater level. It describes a method for seismic reinforcement of existing manholes in which moisture is filtered and released by a hollow pipe.
特許文献２には、既設マンホールの底版を貫通し、非液状化層まで削孔する工程と、拡開可能な複数の抵抗部材を下端に有するステーアンカーを削孔した孔に挿入する工程と、抵抗部材に対して衝撃を加えることにより抵抗部材を拡開させて、抵抗部材を孔の底壁や側壁に進入させる工程と、削孔した孔にセメントを充填する工程と、ステーアンカーの上端をマンホールの底版に固定する工程を含む既設マンホールの浮上沈下防止工法が記載されている。 Patent Document 2 includes a step of drilling through a bottom plate of an existing manhole and drilling to a non-liquefiable layer, a step of inserting a stay anchor having a plurality of expandable resistance members at the lower end into the drilled hole, The step of expanding the resistance member by applying an impact to the resistance member, causing the resistance member to enter the bottom wall or side wall of the hole, the step of filling the drilled hole with cement, and the upper end of the stay anchor A method for preventing the rising and sinking of an existing manhole including a process of fixing to the bottom plate of the manhole is described.
特許文献３には、マンホールの底部に打設されているインバートコンクリートをはつる工程と、マンホールの底部から非液状化層まで削孔する工程と、削孔した孔にアンカー引張材を挿入し、グラウトを注入して、アンカー引張材の先端を非液状化層に定着させる工程と、中央に設けられた開口部からアンカー引張材の上端が突出するように、マンホール底部に受圧板を配置する工程と、アンカー引張材の上端を受圧板に固定する工程と、アンカー引張材の上端をキャップで被覆する工程と、マンホールの底部にインバートコンクリートを打設する工程とを含むことを特徴とする工法が記載されている。 Patent Document 3 includes a step of staking inverted concrete placed at the bottom of the manhole, a step of drilling from the bottom of the manhole to the non-liquefied layer, and inserting an anchor tensile material into the drilled hole, Injecting the grout to fix the tip of the anchor tensile material to the non-liquefied layer, and disposing the pressure receiving plate at the bottom of the manhole so that the upper end of the anchor tensile material protrudes from the opening provided in the center. And a method of fixing the 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 step of placing invert concrete at the bottom of the manhole. Have been described.
しかしながら、特許文献１に記載の内容は、中空パイプにより地下水を消散させるものであるが、消散による浮力の減少のみによってマンホールの浮上防止を図るものであり、地盤に対する引き抜き抵抗力は全く備えていないため、マンホールに及ぶ浮力の程度によっては、マンホールの浮上防止効果が十分に機能しないおそれがある。 However, although the contents described in Patent Document 1 are intended to dissipate groundwater with a hollow pipe, they are intended to prevent the manhole from rising only by reducing the buoyancy caused by the dissipation, and have no pull-out resistance against the ground. Therefore, depending on the degree of buoyancy exerted on the manhole, the effect of preventing the manhole from rising may not function sufficiently.
特許文献２や３に記載の内容は、非液状化層まで深く削孔する必要があり、さらに孔の最深部までグラウト材を注入させる等の作業が必要で、作業性に問題がある。また、マンホールの本体がアンカーで非液状化層まで一体固定されているため、液状化により地盤沈下が発生した場合にマンホールの底版とアンカーとの接合部に力が作用し、接合部が破壊するおそれがある。 The contents described in Patent Documents 2 and 3 require deep drilling up to the non-liquefied layer, and further require work such as injecting a grout material up to the deepest part of the hole, which is problematic in workability. In addition, since the main body of the manhole is integrally fixed to the non-liquefiable layer with an anchor, when ground subsidence occurs due to liquefaction, a force acts on the joint between the bottom plate of the manhole and the anchor, and the joint is destroyed. There is a fear.
本発明は、上記の従来技術の問題点を考慮してなされたものであり、浮上防止杭設置時の作業負荷を軽減し、液状化現象が発生した場合には地下構造物に対する浮力を減少させるとともに浮上防止杭の引き抜き抵抗力を残存させ、地下構造物の浮上を防止することができる地下構造物の浮上防止杭及び地下構造物の浮上防止工法を提供することを目的とする。 The present invention has been made in consideration of the above-mentioned problems of the prior art, and reduces the work load when installing the anti-floating pile, and reduces the buoyancy against the underground structure when liquefaction occurs. It is another object of the present invention to provide a floating prevention pile for an underground structure and a floating prevention method for the underground structure that can prevent the floating of the underground structure by leaving the pulling resistance of the floating prevention pile.
前記目的を達成するため、本発明では、地下構造物の底部に固定される中空パイプ材と、前記中空パイプ材の少なくとも先端側に貫入部と前記中空パイプ材の内外を貫通する複数の透水孔とを備えた地下構造物の浮上防止杭において、前記中空パイプ材は、その上端が地下水位より上側に位置するように前記地下構造物の底部に固定され、該固定状態において、前記透水孔が少なくとも前記地下構造物の底部より下側に位置するようにしたことを特徴とする地下構造物の浮上防止杭を提供する。 To achieve the above object, the present invention, a hollow pipe member that is fixed to the bottom of underground structures, a plurality of water permeable holes through the inside and outside of said the transmural join the club hollow pipe member in at least the distal end side of the hollow pipe member in floating preventing piles of underground construction with bets, the hollow pipe material and its upper end is fixed to the bottom of the underground construction to be positioned above the groundwater level, in the stationary state, the permeability holes providing floating preventing piles of underground construction being characterized in that so as to be positioned below the bottom of at least the underground construction.
好ましくは、前記貫入部には、前記中空パイプ材の外周に形成された螺旋状の羽根を備えている。 Preferably, the penetration portion includes a spiral blade formed on the outer periphery of the hollow pipe material.
また、本発明では、地下構造物の底部に、前記浮上防止杭を貫通させる貫通工程と、前記浮上防止杭により地中に貫入させる貫入工程と、前記地下構造物の底部と前記浮上防止杭とを固定する固定工程とを備え、前記浮上防止杭の少なくとも先端側に形成された貫入部は、地盤を形成する液状化層と非液状化層のうち、液状化層に配されていることを特徴とする地下構造物の浮上防止工法も提供する。 Further, in the present invention, a penetration step of penetrating the levitation prevention pile into the bottom portion of the underground structure, a penetration step of penetrating into the ground by the levitation prevention pile, a bottom portion of the underground structure and the levitation prevention pile, A penetration step formed on at least the tip side of the anti-floating pile is arranged in the liquefied layer among the liquefied layer and the non-liquefied layer forming the ground. It also provides a method for preventing the rise of underground structures.
本発明によれば、地盤が液状化した際に、中空パイプ材に設けられた透水孔から間隙水（地下水）が中空パイプ材の内部に流入し、中空パイプを介して地下構造物内及び地上に排出するので過剰間隙水の水圧が減少し、消散効果を得ることができる。すなわち、地盤の液状化による地下構造物に対する浮力を減少させることができる。また、浮上防止杭の周辺地盤の液状化の度合いも低減させることができるので、地盤に対する浮上防止杭の引き抜き抵抗力も過剰間隙水圧の減少に応じて保持することができ、地下構造物の浮上をより確実に防止できる。つまり、浮上防止杭に形成した貫入部が地盤の液状化層内にとどまった状態において、地盤に対する浮上防止杭の引抜き抵抗力を保持するため、浮上防止杭の貫入深さが浅くて済み、浮上防止杭を設置する時の作業負荷を低減できる。 According to the present invention, when the ground is liquefied, pore water (groundwater) flows into the inside of the hollow pipe material from the water permeable holes provided in the hollow pipe material, and the inside of the underground structure and the ground via the hollow pipe. Since the water pressure is excessively discharged, the water pressure of excess pore water is reduced, and a dissipating effect can be obtained. That is, the buoyancy with respect to the underground structure due to the liquefaction of the ground can be reduced. In addition, since the degree of liquefaction of the ground around the anti-floating pile can be reduced, the pull-out resistance of the anti-floating pile to the ground can be maintained according to the decrease in excess pore water pressure, and the floating of the underground structure It can be prevented more reliably. In other words, when the intrusion part formed in the levitation prevention pile remains in the liquefied layer of the ground, the penetration depth of the levitation prevention pile can be shallow to maintain the pulling resistance of the levitation prevention pile to the ground. The work load when installing prevention piles can be reduced.
本実施例に係る地下構造物１は、下水道のマンホールとして構成されたものであり、その全体形状は略筒形状であり、その内側は少なくとも作業者が通れる程度のスペースが確保されている。実際には、地下構造物１の内壁に配された複数のステップ１１を利用して作業者は地下構造物１内を昇降する。 The underground structure 1 according to the present embodiment is configured as a sewer manhole, and the overall shape thereof is a substantially cylindrical shape, and at least a space that allows an operator to pass through is secured inside. Actually, the operator moves up and down in the underground structure 1 using a plurality of steps 11 arranged on the inner wall of the underground structure 1.
地下構造物１は、円筒形状の直壁体５と一部の周壁が傾斜した斜壁体６とを軸方向に複数連結して形成されており、地下構造物１の下端は、底版４にて閉塞されている。また、地下構造物１を地中に埋設する際は、予め底版４の下側に砕石基礎材１０が敷設されている。地下構造物１の上部には、嵩調整部７を介して受枠８が地表面に合わせて設置されている。ここで、嵩調整部７は、地下構造物１の上面に立設したボルトに螺合させる嵩調整駒（図示しない）や、地下構造物１の上面に載置される複数の調整リング（図示しない）等からなり、嵩調整駒や調整リングにより、受枠８の設置高さが調整される。受枠８には地表面に露出する開口部３が形成されており、この開口部３は開閉可能な蓋体９にて覆われている。 The underground structure 1 is formed by connecting a cylindrical straight wall body 5 and a plurality of slant wall bodies 6 with inclined peripheral walls in the axial direction. The lower end of the underground structure 1 is connected to the bottom plate 4. Blocked. Further, when the underground structure 1 is buried in the ground, a crushed stone foundation material 10 is laid in advance under the bottom plate 4. A receiving frame 8 is installed on the upper portion of the underground structure 1 through the bulk adjusting unit 7 so as to match the ground surface. Here, the bulk adjusting unit 7 includes a bulk adjusting piece (not shown) screwed to a bolt standing on the upper surface of the underground structure 1, and a plurality of adjustment rings (illustrated) placed on the upper surface of the underground structure 1. The installation height of the receiving frame 8 is adjusted by a bulk adjustment piece or an adjustment ring. The receiving frame 8 is formed with an opening 3 exposed to the ground surface, and the opening 3 is covered with a lid 9 that can be opened and closed.
地下構造物１の下方の側面には、流入側及び流出側の配管１４が配設されている。地下構造物１の下端に設けた底版４上には、底版４と一体又は別体として、流入側及び流出側の配管１４に通じる溝１６を形成したインバート１５が設けられている。 An inflow side and an outflow side pipe 14 are arranged on the lower side surface of the underground structure 1. On the bottom slab 4 provided at the lower end of the underground structure 1, an invert 15 having a groove 16 communicating with the inflow side and outflow side pipes 14 is provided as an integral or separate body with the bottom slab 4.
浮上防止杭１２は、地下構造物１の底部（インバート１５及び底版４）に固定した状態において、地下構造物１内から底部を貫通して地中まで延びている。すなわち、浮上防止杭１２の一方の端部が地下構造物１内に、他方の端部が地中に配された状態となっている。また、浮上防止杭１２は地下構造物１の底部に固定されているが、この固定方法には、浮上防止杭１２の外周にフィンを装着させ、フィンを介して固定する方法などがある。浮上防止杭１２の本数は、地下構造物１の大きさ、設置環境による浮上防止杭の貫通方向、要求する引き抜き抵抗力等により適宜設定可能である。 The levitation prevention pile 12 extends from the underground structure 1 to the ground through the bottom while being fixed to the bottom (invert 15 and bottom plate 4) of the underground structure 1. That is, one end of the anti-floating pile 12 is in the underground structure 1 and the other end is arranged in the ground. Further, the levitation prevention pile 12 is fixed to the bottom of the underground structure 1. This fixing method includes a method of attaching fins to the outer periphery of the levitation prevention pile 12 and fixing the fins via the fins. The number of the levitation prevention piles 12 can be set as appropriate depending on the size of the underground structure 1, the penetration direction of the levitation prevention pile depending on the installation environment, the required pulling resistance force, and the like.
この浮上防止杭１２は、中空パイプ材２で形成され、中空パイプ材２の先端側は、貫入部２２が形成されている。本実施例においては、貫入部２２は中空パイプ材２と、その外周に形成された螺旋状の羽根１３からなっている。なお、貫入部２２は、浮上防止杭１２により地中に貫入させる際の貫入効率が良く、地盤に対する浮上防止杭の引き抜き抵抗力を保持することが可能な形状であれば、螺旋状の羽根に限らず、適用可能である。例えば、中空パイプ材２の先端側を中実棒状に形成し、この外周に螺旋状の羽根を設けることも考えられる。この場合、螺旋状の羽根の径を中空パイプ材２の径よりも大きくすることや、螺旋状の羽根の径を先端側から長手方向の上方に向けて徐々に大きくすることや、中実棒状の部分だけでなく、その上側に位置する中空パイプ材２の部分まで延伸させて螺旋状の羽根を設けること等、適宜設定できる。また、螺旋状の羽根ではなく、ドーナツ状の平板を半割りした平板を中空パイプ材２の外周に、間隔を置いて斜めに複数個設け、擬似的な螺旋状の羽根として形成することもできる。このようにすることにより、溶接等により中空パイプに平板を取付ける場合、製造し易いというメリットがある。本実施例では、中空パイプ材２の地下構造物１内の端部は開放され、地中側の端部は閉塞されている。貫入部２２に螺旋状の羽根１３を備えたことにより、浮上防止杭１２を回転させて地中を掘り進める際に、貫入効率が向上し、浮上防止杭１２の設置が容易となり、また、地中に浮上防止杭１２を設置後、浮上防止杭１２の引き抜き抵抗力も保持できる。この螺旋状の羽根１３は、中空パイプ材２の先端側の一部に設けてもよいし、長手方向の一部から全域にわたって設けてもよい。浮上防止杭１２は、この螺旋状の羽根１３も含めて鋳鉄製としてもよいし、鋼材としてもよいが、鋳物製（鋳鉄製、鋳鋼製など）とすることにより、中空パイプ材２と螺旋状の羽根１３を一体的に製造できるというメリットがある。 The levitation prevention pile 12 is formed of a hollow pipe material 2, and a penetration portion 22 is formed on the distal end side of the hollow pipe material 2. In the present embodiment, the penetration portion 22 is composed of the hollow pipe material 2 and the spiral blade 13 formed on the outer periphery thereof. In addition, if the penetration part 22 is a shape in which the penetration efficiency at the time of penetrating into the ground by the levitation prevention pile 12 is good and can hold the pulling-out resistance force of the levitation prevention pile to the ground, a spiral blade is used. It is not limited and can be applied. For example, it is also conceivable to form the hollow pipe member 2 at the front end side in the form of a solid rod and to provide a spiral blade on the outer periphery. In this case, the diameter of the spiral blade is made larger than the diameter of the hollow pipe member 2, the diameter of the spiral blade is gradually increased from the tip side upward in the longitudinal direction, It can be set as appropriate, for example, by providing a spiral blade by extending not only to this part but also to the part of the hollow pipe member 2 located on the upper side. Further, instead of the spiral blades, a plurality of flat plates obtained by halving donut-shaped flat plates can be provided on the outer periphery of the hollow pipe member 2 at an interval to form a pseudo spiral blade. . By doing in this way, when attaching a flat plate to a hollow pipe by welding etc., there exists an advantage that it is easy to manufacture. In this embodiment, the end of the hollow pipe member 2 in the underground structure 1 is opened, and the end on the underground side is closed. By including the spiral blades 13 in the penetrating portion 22, when the anti-floating pile 12 is rotated and dug into the ground, the penetration efficiency is improved, and the anti-floating pile 12 is easily installed. After the anti-floating pile 12 is installed, the pull-out resistance force of the anti-floating pile 12 can be maintained. The spiral blade 13 may be provided on a part of the distal end side of the hollow pipe material 2 or may be provided from a part of the longitudinal direction to the entire region. The levitation prevention pile 12 may be made of cast iron including the spiral blades 13 or may be made of steel, but by making it cast (made of cast iron, cast steel, etc.), the hollow pipe material 2 and the spiral There is an advantage that the blades 13 can be manufactured integrally.
浮上防止杭１２を地下構造物１の底部に固定した状態において、地下構造物１の底部より下側の部位には、透水孔１７が複数形成されている。この透水孔１７は、浮上防止杭１２を形成する中空パイプ材２の内外を貫通している。この透水孔１７を設けることで、地盤が液状化した際に、透水孔１７から間隙水（地下水）が浮上防止杭１２（中空パイプ材２）の内部に流入するので過剰間隙水の水圧が減少し、消散効果を得ることができる。すなわち、地下構造物１に対する浮力を減少させることができる。また、間隙水を地下構造物１内に逃がすことで、地盤の液状化の度合いも低減させることができるので、浮上防止杭１２の引き抜き抵抗力も過剰間隙水圧の減少に応じて保持することができ、地下構造物１の浮上をより確実に防止できる。地下構造物１の浮上を防止することで、地下構造物１の底部（インバート１５及び底版４）の破損も併せて防止できる。すなわち、浮上防止杭１２の先端側の貫入部２２が非液状化層１９まで達していないことから、液状化が発生した際に、地下構造物１の底部と浮上防止杭１２との固定箇所に力が加わり難く、地下構造物１の底部の破損を防止できる。透水孔１７の大きさ、形状、個数及び配置は、浮上防止杭１２の強度及び透水効果に応じて適宜設定可能である。なお、本実施例においては、図１に示すとおり、貫入部２２より上側の中空パイプ材２の部位に透水孔１７を設けているが、貫入部２２の部分にも透水孔１７を設けることもできる。この場合、間隙水の消散効果をよりよく発揮することができる。 In a state where the levitation prevention pile 12 is fixed to the bottom of the underground structure 1, a plurality of water permeable holes 17 are formed in a portion below the bottom of the underground structure 1. This water permeable hole 17 penetrates the inside and outside of the hollow pipe material 2 forming the levitation preventing pile 12. By providing this water permeable hole 17, when the ground is liquefied, pore water (groundwater) flows into the levitation prevention pile 12 (hollow pipe material 2) from the water permeable hole 17, thereby reducing the water pressure of excess pore water. And a dissipating effect can be obtained. That is, the buoyancy with respect to the underground structure 1 can be reduced. Moreover, since the degree of liquefaction of the ground can be reduced by escaping the pore water into the underground structure 1, the pull-out resistance force of the levitation prevention pile 12 can be maintained in accordance with the decrease in the excess pore water pressure. The floating of the underground structure 1 can be prevented more reliably. By preventing the underground structure 1 from rising, damage to the bottom (invert 15 and bottom plate 4) of the underground structure 1 can also be prevented. That is, since the penetration portion 22 on the tip side of the levitation prevention pile 12 does not reach the non-liquefaction layer 19, when liquefaction occurs, the bottom portion of the underground structure 1 and the levitation prevention pile 12 are fixed to the fixed portion. It is difficult to apply force, and damage to the bottom of the underground structure 1 can be prevented. The size, shape, number, and arrangement of the water permeable holes 17 can be appropriately set according to the strength of the levitation preventing pile 12 and the water permeable effect. In the present embodiment, as shown in FIG. 1, the water permeable holes 17 are provided in the portion of the hollow pipe material 2 above the penetrating portion 22, but the water permeable holes 17 may also be provided in the portion of the penetrating portion 22. it can. In this case, the effect of dissipating pore water can be better exhibited.
図３に示すように、浮上防止杭１２の透水孔１７を形成した位置の内面に透水シート２０を貼り付けてもよい。ここでの透水シート２０は、水分のみを通し、砂利や砂等を通過させないものである。また、さらに透水シート２０の内側に透水性の良好な充填剤２１を充填してもよい。このような透水シート２０や充填剤２１を配することで、浮上防止杭１２内の土砂等による目詰まりを防止できる。 As shown in FIG. 3, the water permeable sheet 20 may be affixed to the inner surface of the position where the water permeable holes 17 of the ascent prevention pile 12 are formed. The water permeable sheet 20 here passes only moisture and does not allow gravel or sand to pass through. Further, the water-permeable sheet 20 may be filled with a filler 21 having good water permeability. By providing such a water-permeable sheet 20 and the filler 21, clogging due to earth and sand in the anti-floating pile 12 can be prevented.
浮上防止杭１２を地下構造物１の底部に固定した状態において、浮上防止杭１２の上端は、地下水の水位より上側に位置するように配されている。この浮上防止杭１２の長さは、適宜、中空パイプ材２を連結させ接続することにより現場で調整することもできる。地盤の液状化が起こり、透水孔１７から流入した間隙水は浮上防止杭１２の上端から地下構造物１内に流出する。これにより地下水位が高い場合の平常時の地下水流入を防止することができる。 In a state where the levitation prevention pile 12 is fixed to the bottom of the underground structure 1, the upper end of the levitation prevention pile 12 is arranged so as to be located above the groundwater level. The length of the levitation prevention pile 12 can be adjusted on site by appropriately connecting and connecting the hollow pipe members 2. Liquefaction of the ground occurs, and the interstitial water that has flowed in from the water permeable holes 17 flows into the underground structure 1 from the upper end of the anti-floating pile 12. This can prevent normal groundwater inflow when the groundwater level is high.
一方で、浮上防止杭１２の先端側に形成された貫入部２２は、地中を形成する液状化層１８と非液状化層１９のうち、液状化層１８に配されている。
地盤の液状化が発生するのは、地中に地下水（間隙水）が存在する軟弱な砂層からなる液状化層１８で、この液状化層１８より下には非液状化層１９が存在している。ここで液状化層とは、設計時に液状化に対する対策工を施していない状態において、液状化の可能性があると判断される地盤のことをいい、比較的緩い砂質土であることが多い。一方、非液状化層とは、設計時に液状化が発生しないと判断される地盤のことをいい、比較的締まった砂質土や粘性土であることが多い。本発明では、浮上防止杭１２の先端側が液状化層１８内にとどめた状態において地下構造物１の浮上防止効果を発揮するものであるため、浮上防止杭１２の貫入深さが浅くて済み、設置時の作業負荷が低減する。この効果は、上述した透水孔１７による間隙水の流入と相俟って奏されるものである。すなわち、透水孔１７により消散効果を得ることができ、浮上防止杭１２の周辺地盤の液状化を防止できるので、浮上防止杭１２は非液状化層１９まで達していなくてもアンカー効果を得ることができる。したがって、グラウト材の注入等も不要である。地盤の状態にもよるが、通常、非液状化層１９まで達するには地表面から２０ｍ以上掘削する必要があるが、本実施例においては、浮上防止杭１２はの地下構造物１の下端から３ｍ〜５ｍ程度でアンカー効果を得ることができる場合も有りうる。
On the other hand, the penetration portion 22 formed on the tip side of the levitation prevention pile 12 is arranged in the liquefied layer 18 among the liquefied layer 18 and the non-liquefied layer 19 that form the ground.
The liquefaction of the ground occurs in the liquefied layer 18 composed of a soft sand layer in which underground water (pore water) exists in the ground, and there is a non-liquefied layer 19 below the liquefied layer 18. Yes. Here, the liquefied layer refers to the ground that is considered to be liquefiable in the state where countermeasures against liquefaction are not applied at the time of design, and is often relatively loose sandy soil. . On the other hand, the non-liquefiable layer refers to the ground where it is determined that liquefaction does not occur at the time of design, and is often a relatively tight sandy soil or viscous soil. In the present invention, since the tip of the anti-floating pile 12 exhibits the anti-floating effect of the underground structure 1 in the state where it stays in the liquefied layer 18, the penetration depth of the anti-floating pile 12 can be shallow, The work load during installation is reduced. This effect is produced in combination with the inflow of pore water through the water-permeable holes 17 described above. That is, a dissipating effect can be obtained by the water permeable holes 17, and liquefaction of the ground around the anti-floating pile 12 can be prevented. Can do. Therefore, no grout injection is required. Although it depends on the condition of the ground, it is usually necessary to excavate 20 m or more from the ground surface to reach the non-liquefied layer 19, but in this embodiment, the anti-floating pile 12 is from the lower end of the underground structure 1. There may be a case where the anchor effect can be obtained at about 3 m to 5 m.
本実施例における地下構造物１の浮上防止工法は、以下のとおりである。まず、地中に埋設されている既設の地下構造物１のインバート１５及び底版４に、別途準備した工具を用いて、浮上防止杭１２を挿通可能な貫通孔を貫通させ、この貫通孔に浮上防止杭１２を貫通させる（貫通工程）。次に、インパクトレンチ等を用いて浮上防止杭１２を回転させ、地中に螺旋状の羽根１３を捩じ込むことにより、地中の液状化層１８の途中まで掘削する（掘削工程）。次に、地下構造物１の底版４と浮上防止杭１２とを固定する（固定工程）。これにより、既設の地下構造物１に対し簡単な手順で浮上防止杭１２を設置することができる。 The floating prevention method for the underground structure 1 in the present embodiment is as follows. First, the invert 15 and the bottom slab 4 of the existing underground structure 1 buried in the ground are penetrated with a through-hole through which the anti-floating pile 12 can be inserted using a separately prepared tool, and the levitated to the through-hole. The prevention pile 12 is penetrated (penetration process). Next, the anti-floating pile 12 is rotated using an impact wrench or the like, and the spiral blades 13 are screwed into the ground to excavate the liquefied layer 18 in the ground (excavation process). Next, the bottom plate 4 of the underground structure 1 and the anti-floating pile 12 are fixed (fixing step). Thereby, the levitating prevention pile 12 can be installed with respect to the existing underground structure 1 with a simple procedure.
１ 地下構造物
２ 中空パイプ材
３ 開口部
４ 底版
５ 直壁体
６ 斜壁体
７ 嵩調整部
８ 受枠
９ 蓋体
１０ 砕石基礎材
１１ ステップ
１２ 浮上防止杭
１３ 螺旋状の羽根
１４ 配管
１５ インバート
１６ 溝
１７ 透水孔
１８ 液状化層
１９ 非液状化層
２０ 透水シート
２１ 充填剤
２２ 貫入部
DESCRIPTION OF SYMBOLS 1 Underground structure 2 Hollow pipe material 3 Opening part 4 Bottom plate 5 Straight wall body 6 Slanted wall body 7 Bulk adjusting part 8 Receiving frame 9 Lid body 10 Crushed stone foundation material 11 Step 12 Lifting prevention pile 13 Spiral blade 14 Piping 15 Invert 16 Groove 17 Water permeable hole 18 Liquefaction layer 19 Non-liquefaction layer 20 Water permeable sheet 21 Filler 22 Penetration part
Claims (3)
前記中空パイプ材の少なくとも先端側に貫入部と前記中空パイプ材の内外を貫通する複数の透水孔とを備えた地下構造物の浮上防止杭において、
前記中空パイプ材は、その上端が地下水位より上側に位置するように前記地下構造物の底部に固定され、該固定状態において、前記透水孔が少なくとも前記地下構造物の底部より下側に位置するようにしたことを特徴とする地下構造物の浮上防止杭。 A hollow pipe material fixed to the bottom of the underground structure;
In floating preventing piles of underground construction comprising a plurality of water permeable holes through the inside and outside of said the transmural join the club hollow pipe member in at least the distal end side of the hollow pipe member,
Said hollow pipe member, the upper end is fixed to the bottom of the underground construction to be positioned above the groundwater level, in the fixed state, located below the bottom of the water permeable holes least the underground structures An anti-floating pile for underground structures.
前記浮上防止杭により地中に貫入させる貫入工程と、
前記地下構造物の底部と前記浮上防止杭とを固定する固定工程と
を備え、前記浮上防止杭の少なくとも先端側に形成された貫入部は、地盤を形成する液状化層と非液状化層のうち、液状化層に配されていることを特徴とする請求項１または請求項２に記載の地下構造物の浮上防止杭を用いた地下構造物の浮上防止工法。 A penetration step of penetrating the anti-floating pile at the bottom of the underground structure;
An intrusion step of penetrating into the ground with the anti-floating pile,
A fixing step for fixing the bottom of the underground structure and the anti-floating pile, and the penetration formed on at least the tip side of the anti-floating pile includes a liquefied layer and a non-liquefied layer that form the ground. Of these, the underground structure floating prevention method using the underground structure floating prevention pile according to claim 1, wherein the underground structure floating prevention pile is arranged in a liquefied layer.
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| CN111062144B (en) * | 2019-12-30 | 2023-03-31 | 北京城建勘测设计研究院有限责任公司 | Underground structure buoyancy measuring and calculating method |
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