JP2006070504A - Blasting compaction method - Google Patents

Blasting compaction method Download PDF

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JP2006070504A
JP2006070504A JP2004253068A JP2004253068A JP2006070504A JP 2006070504 A JP2006070504 A JP 2006070504A JP 2004253068 A JP2004253068 A JP 2004253068A JP 2004253068 A JP2004253068 A JP 2004253068A JP 2006070504 A JP2006070504 A JP 2006070504A
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water pressure
pore water
well
ground
blasting
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Yukio Maeda
幸男 前田
Koichi Nagao
浩一 永尾
Shuichi Tsujino
修一 辻野
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Sato Kogyo Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To apply a blasting compaction method also to the building lot ground, the road ground, a river dyke, or the like by positively controlling influence (ground deformation) on the peripheral ground adjoining an improved range. <P>SOLUTION: In this blasting compaction method, a large number of blast holes 3 are formed in the ground at predetermined spaces, and explosives are inserted and installed in the predetermined depth positions of the blast holes 3 and exploded to compact the ground, wherein wells 1 for dissipating excessive pore water pressure are provided beforehand at suitable spaces along a boundary at a boundary part between a soil improved range H and a private land area S where no ground deformation should occur, outside the soil improved range H. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、改良領域に隣接する周辺地盤への影響（地盤変形）を抑制し得る発破締固め工法に関する。   The present invention relates to a blast compaction method capable of suppressing an influence (ground deformation) on a surrounding ground adjacent to an improved region.

従来より、地下水で飽和された緩い砂質土地盤を、爆薬（発破）のエネルギーを利用して人工的に液状化を発生させ、地盤を締固める工法が知られている。この発破締固め工法は、基本的には、発破孔の間隔を設定した後、ボーリングマシンにより地盤中に削孔を行い、装薬のためのケーシングパイプ（樹脂製など）を建て込んだ後、発破孔内に、１または複数段に亘って装薬ユニットを挿入設置し爆発させるものである。   Conventionally, a construction method is known in which loose sandy ground ground saturated with groundwater is artificially liquefied using explosive (blasting) energy to compact the ground. This blast compaction method basically sets the interval between blast holes, drills holes in the ground with a boring machine, and installs casing pipes (such as resin) for charging, A charge unit is inserted and installed in one or a plurality of stages in a blast hole to explode.

前記発破締固め工法に係る先行技術文献としては、例えば下記特許文献１において、埋立地盤内に複数段の爆薬を充填したパイプを埋設し、前記各爆薬を爆圧が水平乃至下部側に向くべく制御した状態で順次下から爆発させて、前記埋立土砂に対する締固め圧力を加えるようにした埋立地盤の発破締固め工法が提案されている。   As a prior art document related to the blast compaction method, for example, in Patent Document 1 below, a pipe filled with a plurality of explosives is buried in a landfill board, and each explosive is directed to a horizontal or lower side. A blasting compaction method for landfills has been proposed in which explosions are made sequentially from below under controlled conditions to apply compaction pressure to the landfill.

また下記特許文献２において、少なくとも発破時以降における地盤内の間隙水圧を測定し、この測定結果に基づいて地盤の締り程度を評価し、この評価結果と目標締り程度との対比に基づいて、少なくとも追加発破実施の可否を決定するようにした発破による軟弱地盤の締固め方法が提案されている。   Further, in the following Patent Document 2, at least the pore water pressure in the ground after the blasting is measured, the degree of ground tightening is evaluated based on the measurement result, and at least based on the comparison between the evaluation result and the target tightening degree. A method of compacting soft ground by blasting that determines whether or not additional blasting can be performed has been proposed.

さらに下記特許文献３において、地盤中に所定間隔で多数の発破孔を形成し、この発破孔の所定深さ位置に爆薬を挿入設置し、前記爆薬を爆発させることにより地盤の締固めを行う第１ステップと、少なくとも前記発破孔周辺の緩み領域を柱状型地盤改良工法によって改良を行うとともに、地盤表層領域を表層型地盤改良工法によって改良を行う第２ステップと、からなる発破工法を併用した地盤改良工法が提案されている。
特開昭６３−１９７７１３号公報 特開平１１−１８１７５４号公報 特開２００２−４７６３８号公報 Further, in Patent Document 3 below, a number of blast holes are formed at predetermined intervals in the ground, an explosive is inserted and installed at a predetermined depth position of the blast hole, and the ground is compacted by exploding the explosive. The ground using the blasting method in combination with one step and the second step of improving at least the loose region around the blasting hole by the columnar type ground improvement method and improving the ground surface region by the surface type ground improvement method An improved construction method has been proposed.
JP-A 63-197713 Japanese Patent Laid-Open No. 11-181754 JP 2002-47638 A

前述した発破締固め工法は、地盤構成粒子の再堆積および間隙水圧の正常化への復帰に伴う締固めによって、より密な地盤組織へと変化させ、その後の液状化を確実に防止するものであり、他の締固め工法と比べて、工期が短くて済む、経済的であるなどの利点を有する。   The blast compaction method described above is to prevent the subsequent liquefaction by changing to a denser ground structure by re-deposition of ground constituent particles and compaction accompanying the return to normalization of pore water pressure. In comparison with other compaction methods, there are advantages such as a short construction period and economic efficiency.

しかし、図１１の改良後における沈下分布例図に示されるように、地盤組織の密度増加に伴って、改良範囲の略中心部では地盤沈下量が１０００mm以上にも達するとともに、爆発による衝撃が同心円状に拡がるため、地盤改良領域に隣接する周辺地盤にもその影響がおよび地盤沈下が生じていた。そのため、これまでは発破締固め工法の対象地域は、広域な埋立地や、改良領域と近隣構造物との距離が相当程度、例えば５０m以上離れている地域に限定せざるを得なかった。   However, as shown in the example of settlement distribution after improvement in FIG. 11, as the density of the ground structure increases, the ground settlement amount reaches 1000 mm or more at the approximate center of the improved range, and the impact due to the explosion is concentric. As a result, the effect on the surrounding ground adjacent to the ground improvement area and land subsidence occurred. Therefore, until now, the target area of the blast compaction method had to be limited to a wide landfill site or an area where the distance between the improved area and the neighboring structure is considerable, for example, 50 m or more.

近隣構造物に影響を及ばさないようにするために従来は、火薬量を調整し衝撃を抑えたり、地盤振動に緩衝を生ずるように複数回の発破を行うなどの方法等を採っていたが、これらの方法では上昇水圧が小さくなるため改良効果が小さくなるとともに、周辺地盤の沈下抑制効果も十分ではなく、周辺地盤にも沈下が発生する可能性があった。   Conventionally, in order not to affect neighboring structures, methods such as adjusting the amount of explosives to suppress impacts and blasting multiple times to create a buffer against ground vibration have been adopted. In these methods, since the rising water pressure is small, the improvement effect is small, and the subsidence suppression effect of the surrounding ground is not sufficient, and the subsidence may occur in the surrounding ground.

そこで本発明の主たる課題は、改良範囲に隣接する周辺地盤への影響（地盤変形）を最小化することにより、例えば宅地地盤や道路地盤、河川堤防などに対しても、当該発破締固め工法を適用可能とすることにある。   Therefore, the main problem of the present invention is to minimize the influence on the surrounding ground adjacent to the improved range (ground deformation), for example, the blast compaction method for residential land, road ground, river embankment, etc. It is to make it applicable.

前記課題を解決するために請求項１に係る発明として、地盤に所定間隔で多数の発破孔を形成し、この発破孔の所定深さ位置に爆薬を挿入設置し、前記爆薬を爆発させることにより地盤の締固めを行う発破締固め工法において、
事前に、地盤改良範囲と、この地盤改良範囲外の地盤変形を生じさせたくない周辺地盤との境界部分に、過剰間隙水圧の消散用井戸を適宜の間隔で設けることを特徴とする発破締固め工法が提供される。 In order to solve the above-mentioned problem, as the invention according to claim 1, by forming a large number of blast holes at predetermined intervals in the ground, inserting and installing an explosive at a predetermined depth position of the blast hole, and exploding the explosive In the blast compaction method of compacting the ground,
Blast compaction characterized by providing wells for dissipating excess pore water pressure at appropriate intervals at the boundary between the ground improvement range and the surrounding ground where it is not desired to cause ground deformation outside this ground improvement range. Construction methods are provided.

上記請求項１記載の発明においては、発破締固め工法の施工に当たり事前に、地盤改良範囲と、この地盤改良範囲外の地盤変形（主に沈下）を生じさせたくない周辺地盤との境界部分に、過剰間隙水圧の消散用井戸を適宜の間隔で設けておき、発破時に前記周辺地盤における過剰間隙水圧の上昇を防ぐことにより、当該周辺地盤の沈下を抑制するものである。その結果、従来は適用対象が広域な埋立地等に限定されていた発破締固め工法を宅地地盤や道路地盤、河川堤防などに対しても適用できるようになり、発破締固め工法の適用範囲を拡大することが可能となる。   In the first aspect of the invention, prior to the construction of the blast compaction method, at the boundary between the ground improvement range and the surrounding ground where the ground deformation outside the ground improvement range (mainly subsidence) is not desired to occur. The wells for dissipating excess pore water pressure are provided at appropriate intervals to prevent the excess pore water pressure from rising in the surrounding ground at the time of blasting, thereby suppressing the settlement of the surrounding ground. As a result, the blast compaction method, which had previously been limited to wide landfills, can now be applied to residential land, road ground, river dikes, etc. It becomes possible to enlarge.

図７に示されるように、液状化層厚ＨＦＬと液状化による沈下量δとの関係は、地震により液状化が発生すると、地盤に平均で約５％の体積ひずみが発生することが判明している。また、図８に示されるように、液状化程度（繰り返し回数Ｎを液状化までの繰り返し回数Ｎｌで割った値）と過剰間隙水圧比の関係は、繰り返し回数が大きいほど過剰間隙水圧比も大きくなり液状化程度も大きいことが分かっているとともに、図９に示されるように、繰り返し回数と体積ひずみεｖとの関係は、繰り返し回数が大きいほど体積ひずみεｖも大きくなることが分かっている。これらより、図１０に示されるように、地盤の体積ひずみεｖの発生、すなわち地盤変形は、過剰間隙水圧比の発生が大きいほど（液状化の程度が大きいほど）大きくなる、との知見に基づき、周辺地盤における過剰間隙水圧の発生を防止することができれば、効果的に周辺地盤の地盤変形を抑制することができるとの考えの下、事前に改良範囲と周辺地盤との境界に過剰間隙水圧の消散用井戸を適宜の間隔で設けることにしたものである。 As shown in FIG. 7, the relationship between the liquefaction layer thickness H FL and the subsidence amount δ due to liquefaction is found that when liquefaction occurs due to an earthquake, an average volume strain of about 5% occurs in the ground. is doing. Further, as shown in FIG. 8, the relationship between the degree of liquefaction (the value obtained by dividing the number of repetitions N by the number of repetitions Nl until liquefaction) and the excess pore water pressure ratio is larger as the number of repetitions is larger. together has been found that liquefaction about even greater now, as shown in FIG. 9, the relationship between the number of repetitions and the volumetric strain epsilon v, it has been found that the greater the volumetric strain epsilon v larger the number of repetitions . From these, as shown in FIG. 10, the generation of the volume strain ε v of the ground, that is, the ground deformation is larger as the excess pore water pressure ratio is larger (the degree of liquefaction is larger). Based on the idea that if it is possible to prevent the generation of excess pore water pressure in the surrounding ground, it is possible to effectively suppress the ground deformation of the surrounding ground. Water pressure dissipating wells are provided at appropriate intervals.

請求項２に係る本発明として、前記過剰間隙水圧の消散用井戸は、空井戸、砕石等の高透水性材料の充填による排水井戸、穴空きパイプによる排水井戸等の静的排水井戸とし、発破時に前記静的排水井戸により過剰間隙水圧の消散を図り、前記周辺地盤における間隙水圧の上昇を抑制する請求項１記載の発破締固め工法が提供される。   As the present invention according to claim 2, the well for dissipating excess pore water pressure is an empty well, a drainage well filled with a highly permeable material such as crushed stone, or a static drainage well such as a drainage well using a perforated pipe. The blast compaction method according to claim 1, wherein the static drainage well sometimes dissipates excess pore water pressure and suppresses the increase in pore water pressure in the surrounding ground.

請求項３に係る本発明として、前記過剰間隙水圧の消散用井戸は、作動開始により周囲の地下水水位を強制的に低下可能とする動的排水井戸とし、
前記動的排水井戸の作動と同時に、或いは作動開始直後に発破を行うことにより、過剰間隙水圧の消散を図り、前記周辺地盤における間隙水圧の上昇を抑制する請求項１記載の発破締固め工法が提供される。 As the present invention according to claim 3, the well for dissipation of excess pore water pressure is a dynamic drainage well that can forcibly lower the surrounding groundwater level by starting operation,
The blast compaction method according to claim 1, wherein the blast compaction method according to claim 1, wherein blasting is performed simultaneously with the operation of the dynamic drain well or immediately after the start of the operation to dissipate excess pore water pressure and suppress an increase in pore water pressure in the surrounding ground. Provided.

上記請求項３記載の本発明においては、前記過剰間隙水圧の消散用井戸として、作動開始により周囲の地下水水位を強制的に低下可能とする動的排水井戸を採用するものであり、上記請求項２記載の発明の静的排水井戸と比べると、タイムラグなく、迅速かつ効果的に過剰間隙水圧の消散を図ることができ、周辺地盤への影響を効果的に最小化できるようになる。   In the present invention described in claim 3, a dynamic drainage well that can forcibly lower the surrounding groundwater level by starting operation is adopted as the well for dissipating excess pore water pressure. Compared with the static drain well of the invention described in 2, the excess pore water pressure can be quickly and effectively dissipated without a time lag, and the influence on the surrounding ground can be effectively minimized.

請求項４に係る本発明として、前記過剰間隙水圧の消散用井戸は、下端が開口とされ、上部側又は上部に接続される流路途中に開閉バルブを備えた内管と、透水性の外管とからなる二重管構造の排水井戸とし、前記内管に圧気を封入して内管内水位を下げた状態としておき、
前記内管の開閉バルブを開放し圧気を放出すると同時に、或いは開閉バルブの開放直後に発破を行うことにより、過剰間隙水圧の消散を図り、前記周辺地盤における間隙水圧の上昇を抑制する請求項１記載の発破締固め工法が提供される。 According to a fourth aspect of the present invention, the well for dissipating excess pore water pressure has an inner pipe having an opening at the lower end and an open / close valve in the middle of the flow path connected to the upper side or the upper part, and a water-permeable outer A double-well drainage well consisting of a pipe, with the inner pipe filled with pressurized air and the water level in the inner pipe lowered,
2. The opening and closing valve of the inner pipe is opened to release pressurized air, or blasting is performed immediately after the opening and closing of the opening and closing valve to dissipate excess pore water pressure and suppress an increase in pore water pressure in the surrounding ground. The blast compaction method described is provided.

請求項５に係る本発明として、前記過剰間隙水圧の消散用井戸は、井戸内に膨縮自在のバルーンを挿入設置した構造とし、前記バルーンに気体を供給しバルーンを膨張させた状態としておき、
前記バルーン内の圧力開放と同時に、或いはバルーン内の圧力の開放直後に発破を行うことにより、過剰間隙水圧の消散を図り、前記周辺地盤における間隙水圧の上昇を抑制する請求項１記載の発破締固め工法が提供される。 As the present invention according to claim 5, the well for dissipation of excess pore water pressure has a structure in which an inflatable balloon is inserted and installed in the well, and the balloon is inflated by supplying gas to the balloon.
The blasting tightening according to claim 1, wherein the blasting is performed simultaneously with the pressure release in the balloon or immediately after the pressure in the balloon is released to dissipate the excess pore water pressure and suppress an increase in the pore water pressure in the surrounding ground. A consolidation method is provided.

請求項６に係る本発明として、前記過剰間隙水圧の消散用井戸は、井戸内に、下端に開閉バルブを備えた管体を挿入設置した構造とし、前記管体内部の空気を排出して負圧状態としておき、
前記管体の下端開閉バルブの開放と同時に、或いは管体の下端開閉バルブの開放直後に発破を行うことにより、過剰間隙水圧の消散を図り、前記周辺地盤における間隙水圧の上昇を抑制する請求項１記載の発破締固め工法が提供される。 According to a sixth aspect of the present invention, the excess pore water pressure dissipating well has a structure in which a tubular body having an open / close valve at the lower end is inserted and installed in the well, and the air inside the tubular body is discharged to be negative. Pressure state,
The blasting is performed simultaneously with the opening of the lower end opening / closing valve of the tubular body or immediately after the opening of the lower end opening / closing valve of the tubular body, thereby dissipating excess pore water pressure and suppressing an increase in the pore water pressure in the surrounding ground. A blast compaction method according to 1 is provided.

請求項７に係る本発明として、前記過剰間隙水圧の消散用井戸は、強制排水可能な揚水井戸とし、
前記強制排水の開始と同時に、或いは強制排水の開始直後に発破を行うことにより、過剰間隙水圧の消散を図り、前記周辺地盤における間隙水圧の上昇を抑制する請求項１記載の発破締固め工法が提供される。 As the present invention according to claim 7, the excess pore water pressure dissipation well is a pumping well capable of forced drainage,
The blast compaction method according to claim 1, wherein the blast compaction method according to claim 1, wherein blasting is performed simultaneously with the start of the forced drainage or immediately after the start of the forced drainage, thereby dissipating excess pore water pressure and suppressing an increase in pore water pressure in the surrounding ground. Provided.

上記請求項４〜７記載の本発明は、請求項３記載の「動的排水井戸」を具体的に列挙したものであり、実施工に当たっては、これらの動的排水井戸のいずれかが好適に採用される。   The present invention according to claims 4 to 7 specifically enumerates the “dynamic drainage wells” according to claim 3, and any of these dynamic drainage wells is suitable for implementation. Adopted.

以上詳説のとおり本発明によれば、改良範囲に隣接する周辺地盤への影響（沈下）を最小化できるようになるため、例えば宅地地盤や道路地盤、河川堤防などに対しても、発破締固め工法を適用することが可能となる。   As described above in detail, according to the present invention, the influence (subsidence) on the surrounding ground adjacent to the improved range can be minimized. For example, blast compaction can be applied to residential ground, road ground, river embankment, etc. The construction method can be applied.

以下、本発明の実施の形態について図面を参照しながら詳述する。   Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

本発明は、図１に示されるように、砂質層の軟弱地盤内に、民地領域Ｓに隣接して、発破による地盤締固め工法による改良範囲Ｈが設定された場合、当該民地領域Ｓにおける地盤変形を伴うことなく、前記改良範囲Ｈの締固めを行うために、図示の如く、地盤改良範囲Ｈと、地盤変形を生じさせたくない民地領域Ｓとの境界部分に、過剰間隙水圧の消散用井戸１を境界に沿って適宜の間隔で設けるようにするものである。   As shown in FIG. 1, in the soft ground of the sandy layer, the present invention is adjacent to the private area S, and when the improved range H by the ground compaction method by blasting is set, the private area In order to perform compaction of the improved range H without ground deformation in S, as shown in the figure, an excess gap is formed at the boundary between the ground improved range H and the private area S where ground deformation is not desired to occur. Water pressure dissipating wells 1 are provided at appropriate intervals along the boundary.

〔過剰間隙水圧の消散用井戸１の形態〕
前記過剰間隙水圧の消散用井戸１としては、種々の井戸が採用可能である。以下、具体的に列挙すると、 [Form of well 1 for dissipating excess pore water pressure]
Various wells can be adopted as the well 1 for dissipating excess pore water pressure. The following is a specific list.

（第１形態例）
最も簡易的には、前記消散用井戸１としては、空井戸、砕石等の高透水性材料の充填による排水井戸、穴空きパイプによる排水井戸等の静的排水井戸とすることができる。前記空井戸は単に素掘した井戸であり、前記砕石等の高透水性材料の充填による排水井戸は、グラベルドレーン工法に代表されるように、砂地盤中に砕石柱を造成することによって構築される排水井戸であり、前記穴空きパイプによる排水井戸はパイプドレーン工法に代表されるように、砂地盤中に穴空きパイプを挿入設置して構築される排水井戸である。 (First embodiment)
Most simply, the dissipating well 1 can be a static drainage well such as an empty well, a drainage well filled with a highly permeable material such as crushed stone, or a drainage well using a perforated pipe. The empty well is simply a well dug, and a drainage well filled with a highly permeable material such as the crushed stone is constructed by creating a crushed stone pillar in the sand ground as represented by the gravel drain method. The drainage well by the perforated pipe is a drainage well constructed by inserting and installing a perforated pipe in the sand ground, as represented by the pipe drain method.

前記静的排水井戸１は、図２に示されるように、不透水層２に達するように設けるのが最も望ましいが、民地領域Ｓにおける過剰間隙水圧比を所定値以下、例えば図１０より過剰間隙水圧比を約０．５乃至０．６以下に抑えることができれば十分であり、発破による衝撃圧は円状に拡散していくため、図１に示されるように、不透水層２に達しない井戸としてもよい。また、前記静的排水井戸１の間隔は、例えば２〜３ｍ、好ましくは１〜２ｍの間隔で配置するのが望ましい。   The static drain well 1 is most preferably provided so as to reach the impermeable layer 2 as shown in FIG. 2, but the excess pore water pressure ratio in the private area S is less than a predetermined value, for example, more than FIG. It is sufficient if the pore water pressure ratio can be suppressed to about 0.5 to 0.6 or less, and since the impact pressure due to blasting diffuses in a circular shape, it reaches the impermeable layer 2 as shown in FIG. It may be a well that does not. Further, the interval between the static drain wells 1 is, for example, 2 to 3 m, preferably 1 to 2 m.

上記静的排水井戸１を、発破による地盤の締固めに先だって、事前に設けておくことにより、発破時に前記静的排水井戸１により過剰間隙水圧の消散を図り、前記民地領域Ｓにおける間隙水圧の上昇を抑制することができる。   The static drain well 1 is provided in advance before the ground is compacted by blasting, so that the excess pore water pressure is dissipated by the static drain well 1 at the time of blasting. Can be suppressed.

（第２形態例）
図３に示される第２形態例に係る過剰間隙水圧の消散用井戸１Ｂは、作動開始により周囲の地下水水位を強制的に低下可能とする動的排水井戸の例を示したものである。 (Second embodiment)
The excess pore water pressure dissipating well 1B according to the second embodiment shown in FIG. 3 is an example of a dynamic drainage well that can forcibly lower the surrounding groundwater level by starting operation.

同図に示される動的排水井戸１Ｂは、下端が開口とされ、上部側又は上部に接続される流路の途中に排気バルブ７を備えた内管５と、該内管５を囲むように配設された透水性の外管６とからなる二重管構造の排水井戸とし、前記内管５へコンプレッサー（図示せず）から圧縮空気を供給可能としたものである。   The dynamic drain well 1B shown in the figure has an opening at the lower end, an inner pipe 5 provided with an exhaust valve 7 in the middle of a flow path connected to the upper side or the upper part, and surrounding the inner pipe 5 A drainage well having a double-pipe structure composed of a water-permeable outer pipe 6 disposed therein, and compressed air can be supplied to the inner pipe 5 from a compressor (not shown).

実施工に当たっては、図３(B)に示されるように、コンプレッサーから圧縮空気を内管５内に供給し、内管５内の水位を下げ、図３(C)のように内管５の下端近傍位置としておく。   As shown in FIG. 3 (B), the compressed air is supplied from the compressor into the inner pipe 5 to lower the water level in the inner pipe 5 as shown in FIG. 3 (B). The position is near the lower end.

この状態から、前記内管５の排気バルブ７を開放し圧気を放出すると同時に、或いは排気バルブ７の開放直後に発破を行うことにより、過剰間隙水圧の消散を図り、前記民地領域Ｓにおける間隙水圧の上昇を抑制する。   From this state, the exhaust valve 7 of the inner pipe 5 is opened to release pressurized air, or blasting is performed immediately after the exhaust valve 7 is opened to dissipate excess pore water pressure. Suppresses the increase in water pressure.

（第３形態例）
図４に示される第３形態例に係る過剰間隙水圧の消散用井戸１Ｃも、作動開始により周囲の地下水水位を強制的に低下可能とする動的排水井戸の例を示したものである。 (Third embodiment)
The excess pore water pressure dissipating well 1C according to the third embodiment shown in FIG. 4 is also an example of a dynamic drainage well that can forcibly lower the surrounding groundwater level by starting operation.

同図に示される動的排水井戸１Ｃは、井戸内に膨縮自在のバルーン８を挿入設置し、開閉バルブ９を開とし、コンプレッサー（図示せず）から圧縮空気を送り、図４(A)に示されるように、バルーン８を膨張させた状態としておく。   The dynamic drain well 1C shown in the figure has an inflatable balloon 8 inserted and installed in the well, the open / close valve 9 is opened, and compressed air is sent from a compressor (not shown). As shown in FIG. 4, the balloon 8 is in an inflated state.

そして、図４(B)に示されるように、開閉バルブ９を開とし前記バルーン８内の圧力開放と同時に、或いはバルーン８内の圧力の開放直後に発破を行うことにより、過剰間隙水圧の消散を図り、前記民地領域Ｓにおける間隙水圧の上昇を抑制する。   Then, as shown in FIG. 4 (B), the opening / closing valve 9 is opened and blasting is performed simultaneously with the release of the pressure in the balloon 8 or immediately after the release of the pressure in the balloon 8, thereby dissipating excess pore water pressure. The increase in pore water pressure in the private area S is suppressed.

（第４形態例）
図５に示される第４形態例に係る過剰間隙水圧の消散用井戸１Ｄも、作動開始により周囲の地下水水位を強制的に低下可能とする動的排水井戸の例を示したものである。 (Fourth embodiment)
The excess pore water dissipation well 1D according to the fourth embodiment shown in FIG. 5 is also an example of a dynamic drainage well that can forcibly lower the surrounding groundwater level by starting operation.

同図に示される動的排水井戸１Ｄは、井戸内に、下端に開閉バルブ１１を備えるとともに上端又は上端に接続される流路途中に開閉バルブ９を備えた管体１０を挿入した構造とし、図５(A)に示されるように、下端開閉バルブ１１を閉とした状態で、真空ポンプ（図示せず）により管体１０内の空気を排気し負圧状態としておく。   The dynamic drainage well 1D shown in the figure has a structure in which a tubular body 10 having an opening / closing valve 11 at the lower end and an opening / closing valve 9 in the middle of a flow path connected to the upper end or the upper end is inserted in the well, As shown in FIG. 5A, in the state where the lower end opening / closing valve 11 is closed, the air in the tube body 10 is exhausted to a negative pressure state by a vacuum pump (not shown).

この状態から、図５(B)に示されるように、前記管体１０の下端開閉バルブ１１の開放と同時に、或いは管体１０の下端開閉バルブ１１の開放直後に発破を行うことにより、過剰間隙水圧の消散を図り、前記民地領域Ｓにおける間隙水圧の上昇を抑制する。   From this state, as shown in FIG. 5B, blasting is performed simultaneously with the opening of the lower end opening / closing valve 11 of the tubular body 10 or immediately after the opening of the lower end opening / closing valve 11 of the tubular body 10, thereby Dissipation of water pressure is attempted, and an increase in pore water pressure in the private area S is suppressed.

（第５形態例）
図６に示される第５形態例に係る過剰間隙水圧の消散用井戸１Ｅも、作動開始により周囲の地下水水位を強制的に低下可能とする動的排水井戸の例を示したものである。 (Fifth embodiment)
An excess pore water pressure dissipating well 1E according to the fifth embodiment shown in FIG. 6 is also an example of a dynamic drainage well that can forcibly lower the surrounding groundwater level by starting operation.

同図に示される動的排水井戸１Ｅは、多数の吸水孔が形成されたストレーナ管１２を井戸中に設置し、排水ポンプ１３により強制的に井戸内の地下水を排水可能としたものである。   A dynamic drainage well 1E shown in the figure is configured such that a strainer pipe 12 in which a large number of water absorption holes are formed is installed in a well, and a drainage pump 13 can forcibly drain groundwater in the well.

そして、図６(B)に示されるように、前記排水ポンプ１３の稼働による強制排水の開始と同時に、或いは強制排水の開始直後に発破を行うことにより、過剰間隙水圧の消散を図り、前記周辺地盤における間隙水圧の上昇を抑制する。なお、排水ポンプに代えて、真空装置を使用することもできる。真空装置による揚水の方が、排水ポンプ１３よりも急速排水が可能であるとともに、経済的であり、むしろ望ましい。   Then, as shown in FIG. 6B, blasting is performed simultaneously with the start of forced drainage by the operation of the drainage pump 13 or immediately after the start of forced drainage, thereby dissipating excess pore water pressure. Suppresses the increase in pore water pressure in the ground. A vacuum apparatus can be used instead of the drainage pump. Pumping water by a vacuum device is more preferable than drainage pump 13 because it allows rapid drainage and is economical.

上記第２〜５形態例に係る動的排水井戸１Ｂ〜１Ｅの場合も、不透水層２に達するように設けるのが最も望ましいが、民地領域Ｓにおける過剰間隙水圧比を所定値以下、例えば図１０より過剰間隙水圧比を約０．５乃至０．６以下に抑えることができれば十分であり、発破による衝撃圧は円状に拡散していくため、図１に示されるように、不透水層２に達しない井戸としてもよい。また、前記動的排水井戸１の間隔は、例えば２〜３ｍ、好ましくは１〜２ｍの間隔で配置するのが望ましい。
〔発破による地盤の締固め〕
以上のように、地盤改良範囲Ｈと、地盤変形を生じさせたくない民地領域Ｓとの境界部分に、過剰間隙水圧の消散用井戸１を境界に沿って適宜の間隔で設置したならば、通常の手順に従って前記改良範囲Ｈの発破締固めを行う。具体的には、ピッチ約５〜１０ｍのグリッド交点部に径約１０〜２０cm程度の発破孔３，３…をボーリングマシンを用いて形成する。この削孔には孔壁保護のために、塩ビ管などの樹脂管をケーシングパイプ４として建て込むようにするのが望ましい。 In the case of the dynamic drainage wells 1B to 1E according to the second to fifth embodiments, it is most desirable to provide the impermeable layer 2, but the excess pore water pressure ratio in the private area S is a predetermined value or less, for example, From FIG. 10, it is sufficient if the excess pore water pressure ratio can be suppressed to about 0.5 to 0.6 or less, and the impact pressure due to blasting diffuses in a circular shape. Therefore, as shown in FIG. A well that does not reach layer 2 may be used. Moreover, it is desirable that the interval between the dynamic drain wells 1 is, for example, 2 to 3 m, preferably 1 to 2 m.
[Consolidation of ground by blasting]
As described above, if the well 1 for dissipating excess pore water pressure is installed at an appropriate interval along the boundary at the boundary between the ground improvement range H and the private area S where the ground deformation is not desired, The improved range H is blasted and compacted according to a normal procedure. Specifically, blast holes 3, 3... Having a diameter of about 10 to 20 cm are formed at a grid intersection having a pitch of about 5 to 10 m using a boring machine. In order to protect the hole wall, it is desirable that a resin pipe such as a vinyl chloride pipe is built in as a casing pipe 4 in the hole.

削孔およびケーシングパイプ４の建込みを完了したならば、地上から所定の深さ位置に装薬ユニットを挿入設置する。この装薬ユニットの設置は、深さ方向の複数箇所、通常は２〜３箇所に分けて設置するのが望ましい。また、発破孔内には前記装薬ユニットと共に、砂、砕石などの粒状物を充填するようにする。また、発破による地盤改良は、複数回、例えば２回に分け、１回目の発破の後、間隙水圧の消散を待って２回目の発破を行うようにすれば、より大きな締固め効果が得られるようになる。   When the drilling and the installation of the casing pipe 4 are completed, the charge unit is inserted and installed at a predetermined depth position from the ground. It is desirable to install this charging unit in a plurality of locations in the depth direction, usually 2 to 3 locations. In addition, the blast hole is filled with granular materials such as sand and crushed stone together with the charge unit. In addition, the ground improvement by blasting is divided into a plurality of times, for example, two times, and after the first blasting, the second blasting is performed after the pore water pressure has been dissipated. It becomes like this.

前記発破により、地下水位以下において、爆発の衝撃力によって間隙水圧が過剰になるとともに、粒子堆積構造が破壊され、当該地盤に液状化が発生する。そして、地盤構成粒子の再堆積および間隙水圧の正常化への復帰に伴い、改良範囲Ｈ内の地盤が締固められる。   Due to the blasting, the pore water pressure becomes excessive due to the impact force of the explosion below the groundwater level, the particle accumulation structure is destroyed, and liquefaction occurs in the ground. Then, the ground within the improved range H is compacted with the re-deposition of the ground constituent particles and the return to normalization of the pore water pressure.

本発明に係る発破締固め工法の施工要領図（その１）である。FIG. 3 is a construction diagram (part 1) of a blast compaction method according to the present invention. 本発明に係る発破締固め工法の施工要領図（その２）である。It is a construction procedure figure (the 2) of the blast compaction construction method which concerns on this invention. 第２形態例に係る過剰間隙水圧の消散用井戸１Ｂを示す図である。It is a figure which shows the well 1B for dissipation of the excess pore water pressure which concerns on a 2nd form example. 第３形態例に係る過剰間隙水圧の消散用井戸１Ｃを示す図である。It is a figure which shows the well 1C for the dissipation of the excess pore water pressure which concerns on a 3rd form example. 第４形態例に係る過剰間隙水圧の消散用井戸１Ｄを示す図である。It is a figure which shows 1D of wells for dissipation of the excess pore water pressure which concern on a 4th form example. 第５形態例に係る過剰間隙水圧の消散用井戸１Ｅを示す図である。It is a figure which shows the well 1E for the dissipation of the excess pore water pressure which concerns on a 5th form example. 液状化層厚ＨＦＬと液状化による沈下量δとの関係図である。FIG. 4 is a relationship diagram between a liquefied layer thickness HFL and a settlement amount δ due to liquefaction. 液状化程度（繰り返し回数Ｎを液状化までの繰り返し回数Ｎｌで割った値）と過剰間隙水圧比の関係図である。It is a relationship diagram between the degree of liquefaction (the value obtained by dividing the number of repetitions N by the number of repetitions Nl until liquefaction) and the excess pore water pressure ratio. 繰り返し回数と体積ひずみεｖとの関係図である。Is a graph showing the relationship between number of repetitions and the volumetric strain epsilon v. 過剰間隙水圧比と体積ひずみεｖとの関係図である。Is a graph showing the relationship between excess pore water pressure ratio and volumetric strain epsilon v. 改良後における沈下分布例図である。It is a subsidence distribution example figure after improvement.

符号の説明Explanation of symbols

１…消散用井戸、２…不透水層、３…発破孔、４…ケーシングパイプ、Ｈ…改良範囲、Ｓ…民地領域   DESCRIPTION OF SYMBOLS 1 ... Dissipation well, 2 ... Impervious layer, 3 ... Blast hole, 4 ... Casing pipe, H ... Improvement area, S ... Private area

Claims (7)

地盤に所定間隔で多数の発破孔を形成し、この発破孔の所定深さ位置に爆薬を挿入設置し、前記爆薬を爆発させることにより地盤の締固めを行う発破締固め工法において、
事前に、地盤改良範囲と、この地盤改良範囲外の地盤変形を生じさせたくない周辺地盤との境界部分に、過剰間隙水圧の消散用井戸を適宜の間隔で設けることを特徴とする発破締固め工法。 In the blast compaction method of forming a large number of blast holes in the ground at predetermined intervals, inserting and installing an explosive at a predetermined depth position of the blast hole, and compacting the ground by exploding the explosive,
Blast compaction characterized by providing wells for dissipating excess pore water pressure at appropriate intervals at the boundary between the ground improvement range and the surrounding ground where it is not desired to cause ground deformation outside this ground improvement range. Construction method. 前記過剰間隙水圧の消散用井戸は、空井戸、砕石等の高透水性材料の充填による排水井戸、穴空きパイプによる排水井戸等の静的排水井戸とし、発破時に前記静的排水井戸により過剰間隙水圧の消散を図り、前記周辺地盤における間隙水圧の上昇を抑制する請求項１記載の発破締固め工法。   The excess pore water pressure dissipating well is a static drain well such as an empty well, a drainage well filled with a highly permeable material such as crushed stone, or a drainage well using a perforated pipe. The blast compaction method according to claim 1, wherein the water pressure is dissipated to suppress an increase in pore water pressure in the surrounding ground. 前記過剰間隙水圧の消散用井戸は、作動開始により周囲の地下水水位を強制的に低下可能とする動的排水井戸とし、
前記動的排水井戸の作動と同時に、或いは作動開始直後に発破を行うことにより、過剰間隙水圧の消散を図り、前記周辺地盤における間隙水圧の上昇を抑制する請求項１記載の発破締固め工法。 The excess pore water dissipating well is a dynamic drainage well that can forcibly lower the surrounding groundwater level by starting operation,
The blast compaction method according to claim 1, wherein excess blast water pressure is dissipated by performing blasting simultaneously with the operation of the dynamic drain well or immediately after the operation is started to suppress an increase in the pore water pressure in the surrounding ground. 前記過剰間隙水圧の消散用井戸は、下端が開口とされ、上部側又は上部に接続される流路途中に開閉バルブを備えた内管と、透水性の外管とからなる二重管構造の排水井戸とし、前記内管に圧気を封入して内管内水位を下げた状態としておき、
前記内管の開閉バルブを開放し圧気を放出すると同時に、或いは開閉バルブの開放直後に発破を行うことにより、過剰間隙水圧の消散を図り、前記周辺地盤における間隙水圧の上昇を抑制する請求項１記載の発破締固め工法。 The excess pore water pressure dissipating well has a double-tube structure consisting of an inner pipe having an opening and closing valve in the middle of a flow path connected to the upper side or the upper part, and a water-permeable outer pipe. Let it be a drain well, and keep the water level in the inner pipe lowered by enclosing pressurized air in the inner pipe,
2. The opening and closing valve of the inner pipe is opened to release pressurized air, or blasting is performed immediately after the opening and closing of the opening and closing valve to dissipate excess pore water pressure and suppress an increase in pore water pressure in the surrounding ground. The blast compaction method described. 前記過剰間隙水圧の消散用井戸は、井戸内に膨縮自在のバルーンを挿入設置した構造とし、前記バルーンに気体を供給しバルーンを膨張させた状態としておき、
前記バルーン内の圧力開放と同時に、或いはバルーン内の圧力の開放直後に発破を行うことにより、過剰間隙水圧の消散を図り、前記周辺地盤における間隙水圧の上昇を抑制する請求項１記載の発破締固め工法。 The excess pore water pressure dissipation well has a structure in which an inflatable balloon is inserted and installed in the well, and the balloon is inflated by supplying gas to the balloon.
The blasting tightening according to claim 1, wherein the blasting is performed simultaneously with the pressure release in the balloon or immediately after the pressure in the balloon is released to dissipate the excess pore water pressure and suppress an increase in the pore water pressure in the surrounding ground. Hardening method. 前記過剰間隙水圧の消散用井戸は、井戸内に、下端に開閉バルブを備えた管体を挿入設置した構造とし、前記管体内部の空気を排出して負圧状態としておき、
前記管体の下端開閉バルブの開放と同時に、或いは管体の下端開閉バルブの開放直後に発破を行うことにより、過剰間隙水圧の消散を図り、前記周辺地盤における間隙水圧の上昇を抑制する請求項１記載の発破締固め工法。 The excess pore water pressure dissipating well has a structure in which a tubular body having an open / close valve is inserted and installed in the well, and the air inside the tubular body is discharged to be in a negative pressure state.
The blasting is performed simultaneously with the opening of the lower end opening / closing valve of the tubular body or immediately after the opening of the lower end opening / closing valve of the tubular body, thereby dissipating excess pore water pressure and suppressing an increase in the pore water pressure in the surrounding ground. The blast compaction method according to 1. 前記過剰間隙水圧の消散用井戸は、強制排水可能な揚水井戸とし、
前記強制排水の開始と同時に、或いは強制排水の開始直後に発破を行うことにより、過剰間隙水圧の消散を図り、前記周辺地盤における間隙水圧の上昇を抑制する請求項１記載の発破締固め工法。
The excess pore water pressure dissipation well is a pumping well capable of forced drainage,
The blast compaction method according to claim 1, wherein blasting is performed simultaneously with the start of forced drainage or immediately after the start of forced drainage to dissipate excess pore water pressure and suppress an increase in pore water pressure in the surrounding ground.
JP2004253068A 2004-08-31 2004-08-31 Blasting compaction method Pending JP2006070504A (en)

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CN113375515A (en) * 2021-07-21 2021-09-10 中国十五冶金建设集团有限公司 Blasting compaction device and method for blasting compaction of soil slope by using same

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JPH03187415A (en) * 1989-12-15 1991-08-15 Shimizu Corp Foundation structure of structure
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113375515A (en) * 2021-07-21 2021-09-10 中国十五冶金建设集团有限公司 Blasting compaction device and method for blasting compaction of soil slope by using same
CN113375515B (en) * 2021-07-21 2023-01-17 中国十五冶金建设集团有限公司 Blasting compaction device and method for blasting compaction of soil slope by using same

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