JP6693090B2 - Management method for secondary slime treatment - Google Patents

Management method for secondary slime treatment Download PDF

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JP6693090B2
JP6693090B2 JP2015217677A JP2015217677A JP6693090B2 JP 6693090 B2 JP6693090 B2 JP 6693090B2 JP 2015217677 A JP2015217677 A JP 2015217677A JP 2015217677 A JP2015217677 A JP 2015217677A JP 6693090 B2 JP6693090 B2 JP 6693090B2
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stabilizing solution
slime treatment
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直之 喜多
直之 喜多
真 荒川
真 荒川
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Obayashi Corp
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Description

本発明は、安定液を満たした掘削孔にて1次スライム処理および2次スライム処理を実施する際の、2次スライム処理の管理方法に関する。   The present invention relates to a method for managing secondary slime treatment when performing primary slime treatment and secondary slime treatment in a drill hole filled with a stabilizing solution.

地盤中に現場打ちコンクリート杭や地中連続壁等のコンクリート構造物を構築するにあたり、安定液を供給しつつ地中を掘削して柱状もしくは溝状の掘削孔を形成する工法では、掘削完了後、掘削孔内の安定液を所要時間静置して安定液中に浮遊する土砂分を沈殿させ、孔底に堆積してスライムとなった土砂分を除去する1次スライム処理を行う。また、コンクリートの打設前には、1次スライム処理後に孔底に堆積してスライムとなった沈降速度の遅い砂分を、安定液と共に吸引除去する2次スライム処理を行う。   When constructing concrete structures such as cast-in-place concrete piles and underground walls in the ground, the method of excavating the ground while forming a columnar or groove-like drilling hole while supplying a stable liquid The primary slime treatment is performed in which the stabilizing solution in the drill hole is allowed to stand for a required time to precipitate sediment floating in the stabilizing solution, and the sediment deposited on the bottom of the hole to form slime is removed. In addition, before pouring concrete, a secondary slime treatment is performed in which the sand having a slow sedimentation rate, which has become slime by depositing at the bottom of the hole after the primary slime treatment, is removed by suction together with the stabilizing solution.

そして、例えば、特許文献1には、杭孔の底部に堆積したスライムを杭孔内の安定液とともに吸引し、杭孔外に排出するためのスライム除去装置が開示されている。   Then, for example, Patent Document 1 discloses a slime removing device for sucking slime accumulated on the bottom of the pile hole together with the stabilizing liquid in the pile hole and discharging the slime outside the pile hole.

このようなスライム除去装置を利用した2次スライム処理の管理方法は、一般に、スライム処理装置から排出される孔底近傍の安定液に対して砂分率の測定を行う、もしくは、孔底近傍の安定液を採取して砂分率の測定を行う、などして孔底近傍における安定液の砂分率が、所定の管理基準値以下になるまでスライムの除去処理を継続する、というものである。   The management method of the secondary slime treatment using such a slime removing device generally measures the sand fraction of the stabilizing solution discharged from the slime processing device in the vicinity of the bottom of the hole, or in the vicinity of the bottom of the hole. By collecting the stabilizing solution and measuring the sand content, etc., the slime removal process is continued until the sand content of the stabilizing solution near the bottom of the hole is below a prescribed control reference value. ..

しかし、上記の2次スライム処理の管理方法では、杭孔中間部や杭孔口部近傍の安定液について状態把握を行っていないため、2次スライム処理終了後からコンクリートの打設作業前の間に不慮の時間を要した場合、浮遊していた砂分が沈降して孔底にスライムが堆積する可能性があり、構築後のコンクリート構造物に対して、スライムに起因する沈下や先端支持力の低下を招く恐れが生じる。   However, in the above management method of the secondary slime treatment, since the state of the stabilizing liquid in the middle portion of the pile hole and the vicinity of the mouth portion of the pile hole is not grasped, the state after the completion of the secondary slime treatment and before the concrete pouring work is completed. If it takes an unreasonable amount of time, the suspended sand content may settle down and slime may accumulate at the bottom of the hole, which may cause subsidence or tip support force due to slime on the concrete structure after construction. May occur.

このような中、例えば、特許文献2には、杭孔の底部に注入袋体を配置した状態で上方にコンクリートを打設し、コンクリートの硬化後に注入袋体内に注入材を注入して杭先端から下方に向けて膨張させることで孔底地盤にプレロードを与え、孔底地盤をあらかじめ圧縮させて杭先端の強化を図る、場所打ちコンクリート杭工法が開示されている。   In such a situation, for example, in Patent Document 2, concrete is placed above in a state where the injection bag body is arranged at the bottom of the pile hole, and after the concrete hardens, the injection material is injected into the injection bag body and the tip of the pile. Has been disclosed, there is disclosed a cast-in-place concrete pile method in which the hole bottom ground is pre-loaded by expanding downward and the hole bottom ground is compressed in advance to strengthen the pile tip.

特開2000−120067号公報JP, 2000-120067, A 特許3688546号公報Japanese Patent No. 3688546

特許文献2に開示された方法によれば、注入袋体の膨張により、注入袋体の下方にスライムが存在していたとしてもこれを押出し排出することができ、また、杭先端地盤を圧縮させることにより、地盤の応力開放の改善を図ることができるため、場所打ちコンクリート杭の初期沈下を小さくすることが可能となる。   According to the method disclosed in Patent Document 2, even if slime exists below the injection bag body due to the expansion of the injection bag body, the slime can be pushed out and discharged, and the pile tip ground is compressed. As a result, the stress relief of the ground can be improved, and the initial settlement of the cast-in-place concrete pile can be reduced.

しかし、特許文献2の方法では、杭先端地盤にプレロード圧を作用させる作業が煩雑であるとともに、プレロード圧の大きさや圧力保持時間の長さ等を設定する方法が確立されておらず、また、孔底に堆積したスライムを十分押し出し排出できたか否かについて確認することも容易ではない。   However, in the method of Patent Document 2, the work of applying the preload pressure to the pile tip ground is complicated, and the method of setting the magnitude of the preload pressure, the length of the pressure holding time, and the like has not been established. It is not easy to confirm whether or not the slime deposited on the bottom of the hole has been pushed out sufficiently and discharged.

本発明は、かかる課題に鑑みなされたものであって、その主な目的は、安定液を満たした掘削孔にコンクリートを打設して場所打ちコンクリート造の構造物を施工する方法において、2次スライム処理終了後の安定液を静置しても、孔底にスライムの堆積をほぼ生じない、2次スライム処理の管理方法を提供することである。   The present invention has been made in view of the above problems, and its main purpose is to place a concrete in an excavation hole filled with a stabilizing liquid to construct a cast-in-place concrete structure. It is an object of the present invention to provide a method for controlling a secondary slime treatment in which slime is hardly deposited on the bottom of a hole even if the stabilizing solution after the slime treatment is allowed to stand.

かかる目的を達成するため、本発明の2次スライム処理の管理方法は、安定液を満たした掘削孔にて1次スライム処理および2次スライム処理を実施した後、前記掘削孔にコンクリートを打設して場所打ちコンクリート造の構造物を構築する方法における、2次スライム処理の管理方法であって、1次スライム処理後に安定液を所定時間静置して、浮遊していた沈降速度の遅い砂分の沈降が進んだところで開始し、孔底近傍に設置したサンプラーから採取したサンプルによる、安定液の砂分率の定点測定を一定時間ごとに繰り返し行い、前記孔底近傍の安定液の砂分率が、施工現場ごとに定められた管理基準値以下となることを確認する工程と、少なくとも孔口近傍に設置したサンプラーから採取したサンプルによる、安定液の砂分率の定点測定を行い、同時刻に測定した孔底近傍の安定液の砂分率と同一もしくは近似する数値となることを確認する工程と、を備え、両工程の確認が終了するまで、前記2次スライム処理を継続することを特徴とする。 In order to achieve such an object, the management method of the secondary slime treatment of the present invention is such that after performing the primary slime treatment and the secondary slime treatment in a drill hole filled with a stabilizing solution, concrete is poured into the drill hole. A method for controlling secondary slime treatment in a method for constructing a cast-in-place concrete structure, in which the stabilizing solution is allowed to stand for a predetermined time after the primary slime treatment, and the suspended sand having a slow sedimentation rate Minute settling progressed, and fixed point measurement of the sand fraction of the stable solution was repeated at regular intervals using a sample taken from a sampler installed near the bottom of the hole. rate is, the step of confirming that the following control reference value determined for each construction site, by samples taken from the sampler installed in the vicinity of at least the hole opening, the sand fraction of the stabilizer fixed point Was treated with constant until and a step of confirming that the numerical value that sand fraction identical or approximation of the stabilizing solution of the holes near the bottom, measured at the same time, confirmation of the both steps are completed, the secondary slime The feature is that the processing is continued.

上述する本発明の2次スライム処理の管理方法によれば、前記孔底近傍の安定液の砂分率が施工現場ごとに定められた管理基準値以下となることを確認するとともに、孔口近傍の安定液の砂分率を孔底近傍の安定液の砂分率と同一もしくは近似する数値とすることで、2次スライム処理終了後の掘削孔内全体の安定液について、砂分率を施工現場ごとに定められた管理基準値以下とし、時間の経過とともに沈降する可能性の高い砂分が大幅に低減された状態にすることができる。これにより、2次スライム処理後からコンクリート打設作業までに多大な時間を要した場合にも、コンクリートの打設直前時における掘削孔の孔底には、スライムの堆積をほぼ生じない。したがって、構築後の構造物に対して、スライムに起因する沈下および先端支持力の低下を抑制することが可能となる。   According to the management method of the secondary slime treatment of the present invention described above, it is confirmed that the sand fraction of the stabilizing solution near the hole bottom becomes equal to or less than the management reference value set for each construction site, and the vicinity of the hole mouth By setting the sand fraction of the stabilizing solution of No. 2 to be the same as or approximating the sand fraction of the stabilizing solution near the hole bottom, the sand fraction of the entire stabilizing solution in the drill hole after the secondary slime treatment is applied. It is possible to reduce the amount of sand that is likely to settle with the passage of time to a level that is less than or equal to the control standard value set for each site. As a result, even when it takes a long time from the secondary slime treatment to the concrete placing work, slime is hardly deposited on the bottom of the excavation hole immediately before the concrete is placed. Therefore, it is possible to suppress the sinking and the decrease in the tip supporting force due to slime in the structure after construction.

また、2次スライム処理終了後の安定液は、掘削孔内全域の砂分率が一様に管理された状態にあるため、コンクリート打設時の置換不良を生じることがなく、高品質の現場打ちコンクリート造の構造物を構築することが可能となる。   In addition, since the stabilizing liquid after the secondary slime treatment is in a state in which the sand content in the entire borehole is controlled uniformly, there is no displacement failure during concrete pouring, and high quality on-site. It is possible to construct a structure made of poured concrete.

本発明の2次スライム処理の管理方法は、安定液を満たした掘削孔にて1次スライム処理および2次スライム処理を実施した後、前記掘削孔にコンクリートを打設して場所打ちコンクリート造の構造物を構築する方法における、2次スライム処理の管理方法であって、1次スライム処理後に安定液を所定時間静置して浮遊していた沈降速度の遅い砂分の沈降が進んだところで開始し、孔底近傍に設置したサンプラーから採取したサンプルによる、安定液の砂分率の定点測定を一定時間ごとに繰り返し行い、前記孔底近傍の安定液の砂分率が施工現場ごとに定められた管理基準値以下となることを確認する工程と、少なくとも孔底近傍の安定液の比重と孔口近傍の安定液の比重の定点測定を、孔底近傍及び孔口近傍に設置したサンプラーから採取したサンプルにより行い、同時刻に測定した両者の比重が、施工現場ごとに定められた管理基準値の範囲内に収まることを確認する工程と、を備え、両工程の確認が終了するまで、前記2次スライム処理を継続することを特徴とする。 The management method of the secondary slime treatment of the present invention is to perform a primary slime treatment and a secondary slime treatment in an excavation hole filled with a stabilizing solution, and then place concrete in the excavation hole to form a cast-in-place concrete structure. This is a method for controlling the secondary slime treatment in the method of constructing a structure, and starts when the sedimentation of the sand with a slow sedimentation speed that has been floating by leaving the stabilizing liquid for a predetermined time after the primary slime treatment has progressed. Then, a fixed point measurement of the sand fraction of the stabilizing solution by a sample taken from a sampler installed near the bottom of the hole was repeatedly performed at regular intervals, and the sand fraction of the stabilizing solution near the hole bottom was determined for each construction site. and a step of confirming the following become possible management reference value, the stable liquid fixed-point measurement of the specific gravity of the specific gravity and the bore hole at least near the bottom hole vicinity of the stabilizing solution, adopted from the sampler installed in the hole near the bottom and the hole opening neighborhood Carried out by sample, to the specific gravity of both measured at the same time, a step of confirming that fall within the scope of the management reference value set for each construction site, with the confirmation of the both steps are completed, the The feature is that the secondary slime treatment is continued.

上述する本発明の2次スライム処理の管理方法によれば、比重と砂分率が相関関係にあることから、2次スライム処理の管理を砂分率のみで行う方法と同様に、スライムの堆積抑制効果やコンクリートとの良好な置換機能を保持効果が得られるとともに、2次スライム処理終了後の安定液が、掘削孔内全域の比重を一様に管理された状態にあるため、施工現場で地盤条件のことなる掘削孔ごとに、掘削孔内全体の安定液が良好な性状を有しているか否かの評価を行うことが可能となる。   According to the above-described method for managing secondary slime treatment of the present invention, since the specific gravity and the sand content are in correlation, as in the method for performing the management of the secondary slime processing only by the sand content, slime deposition In addition to the suppression effect and the good replacement function with concrete being retained, the stabilizing solution after the secondary slime treatment is in a state where the specific gravity of the entire borehole is controlled uniformly, so that it is possible to use it at the construction site. It becomes possible to evaluate whether or not the stable liquid in the entire drill hole has good properties for each drill hole having different ground conditions.

本発明によれば、2次スライム処理終了後の掘削孔内全体の安定液を、時間の経過とともに沈降する可能性の高い砂分が大幅に低減された状態にすることができる。これにより、2次スライム終了後からコンクリート打設作業までに多大な時間を要した場合にも、掘削孔の孔底にスライムの堆積をほぼ生じることなく、構築後の構造物に対して、スライムに起因する沈下および先端支持力の低下を抑制することが可能となる。   According to the present invention, the stabilizing liquid in the entire excavation hole after the secondary slime treatment can be brought into a state in which the sand content that is highly likely to settle with the passage of time is significantly reduced. As a result, even if a large amount of time is required from the completion of the secondary slime to the concrete placing work, slime does not almost accumulate on the bottom of the drilling hole, and the slime can be applied to the constructed structure. It is possible to suppress the subsidence and the lowering of the tip supporting force due to.

1次スライム処理終了後の掘削孔を示す図である。It is a figure which shows the excavation hole after completion | finish of a primary slime process. 掘削孔内の安定液の状態を示すグラフである。It is a graph which shows the state of the stable liquid in an excavation hole. 2次スライム処理実施中の掘削孔を示す図である。It is a figure showing an excavation hole under secondary slime processing implementation.

本発明の2次スライム処理の管理方法は、地盤中に場所打ちコンクリート造の構造物を構築する工法であって、安定液が満たされた掘削孔にて1次スライム処理および2次スライム処理を実施する工程を含む工法に採用するものである。したがって、アースドリル工法、リバース工法、オールケーシング工法等の場所打ち杭工法や地中連続壁工法に採用可能であり、掘削孔の形状も、柱状もしくは溝状のいずれでもよく、構築される構造物も地中連続壁や基礎杭等いずれでもよい。   The control method of the secondary slime treatment of the present invention is a method of constructing a structure of cast-in-place concrete structure in the ground, and performs the primary slime treatment and the secondary slime treatment in the drill hole filled with the stabilizing solution. It is adopted in the construction method including the steps to be carried out. Therefore, it can be used for cast-in-place pile construction methods such as earth drill construction method, reverse construction method, all casing construction method and underground continuous wall construction method, and the shape of the drill hole may be columnar or grooved, and the structure to be constructed It may be a continuous underground wall or foundation pile.

また、掘削孔を満たす安定液は、ベントナイト安定液やポリマー安定液等いずれでもよく、地盤状況や打設しようとするコンクリートの性状等に応じて、孔壁の安定保持性、掘削土砂の分離性およびコンクリートの置換性を考慮し、適宜配合したものを採用すればよい。   The stabilizing solution that fills the drill hole may be bentonite stabilizing solution, polymer stabilizing solution, etc., depending on the ground conditions and the properties of the concrete to be placed, the stability of the hole wall and the separability of excavated soil Also, in consideration of the substitutability of concrete, it is advisable to adopt an appropriate mixture.

本実施の形態では、アースドリル工法にて場所打ちコンクリート杭を構築するべく、地中に柱状の掘削孔を形成し、その内方をベントナイト系の安定液で満たした場合を事例として、図1〜図3を参照しつつ以下に説明する。   In the present embodiment, in order to construct a cast-in-place concrete pile by the earth drill method, a case where a columnar drilling hole is formed and the inside thereof is filled with a bentonite-based stabilizing solution is taken as an example, and FIG. ~ It demonstrates below, referring FIG.

図1で示すように、掘削孔1は、対象地盤の表層7に対してケーシング3を建込んだ後、土質に適合した安定液2を注入しながら図示しないドリリングバケットを回転させて掘削されたもので、支持層8まで根入れ掘削されている。また、掘削作業の終了後には、一定時間静置して安定液2中に浮遊する土砂分を自然沈降させ、掘削孔1の孔底に堆積してスライムとなった土砂分を、底浚いバケット等にて地上に排出する1次スライム処理を行っている。   As shown in FIG. 1, the excavation hole 1 was excavated by constructing the casing 3 on the surface layer 7 of the target ground and then rotating a drilling bucket (not shown) while pouring the stabilizing liquid 2 suitable for the soil condition. It has been excavated into the support layer 8. After the completion of the excavation work, the sediment content floating in the stabilizing solution 2 is allowed to stand for a certain period of time to spontaneously settle, and the sediment content that has accumulated on the bottom of the excavation hole 1 and becomes slime is removed from the bucket. The primary slime treatment that discharges to the ground is carried out.

掘削孔1の安定液2中には、図2(a)の深度と比重の関係を示すグラフからわかるように、1次スライム処理終了時(時点t1)に沈降しなかった沈降速度の遅い微細な砂分が浮遊しており、深度方向全体の比重が高い状態にある。そして、掘削孔1の安定液2を所定時間静置すると(時点t2)、安定液2中を浮遊していた微細な砂分が徐々に沈降するため、深度方向全体で比重も徐々に低下し、沈降した砂分がスライムとして孔底に堆積していく様子がわかる。   As can be seen from the graph showing the relationship between depth and specific gravity in the stabilizing solution 2 in the drill hole 1, fine particles with a slow sedimentation rate that did not sediment at the end of the primary slime treatment (time point t1). The sand content is floating and the specific gravity of the entire depth direction is high. Then, when the stabilizing solution 2 in the drill hole 1 is allowed to stand for a predetermined time (time point t2), the fine sand particles floating in the stabilizing solution 2 gradually settle, so that the specific gravity also gradually decreases in the entire depth direction. It can be seen that the sedimented sand is deposited as slime on the bottom of the hole.

このため、掘削孔1に対する2次スライム処理は、1次スライム処理後に安定液2を所定時間静置して浮遊していた沈降速度の遅い砂分の沈降が進んだところ(時点t2)で開始する。なお、2次スライム処理を開始する時刻(時点t2)の選定方法としては、例えば、図1で示すように、掘削孔1の孔口近傍における特定深度にサンプラー61を設置し、一定時間ごとに安定液2を採取して比重の定点測定を行う。そして、安定液2中に浮遊する砂分の沈降速度や安定液2の性状、現場状況等を考慮して、2次スライム処理を開始する基準となる比重を予め設定しておき、定点測定した比重が基準となる比重まで低減した時刻を、2次スライム処理を開始する時刻として選定する方法が採用できる。   For this reason, the secondary slime treatment for the drill hole 1 is started after the sedimentation of the sand having a slow sedimentation speed, which was left floating after the stabilizing liquid 2 was left standing for a predetermined time after the primary slime treatment (time t2). To do. As a method of selecting the time (time point t2) for starting the secondary slime treatment, for example, as shown in FIG. 1, the sampler 61 is installed at a specific depth near the mouth of the excavation hole 1 and is set at regular intervals. Stabilizer 2 is sampled and the specific gravity is measured at a fixed point. Then, in consideration of the sedimentation velocity of the sand floating in the stabilizing solution 2, the properties of the stabilizing solution 2, the situation at the site, etc., the specific gravity which is the standard for starting the secondary slime treatment is set in advance, and the fixed point is measured. A method can be adopted in which the time when the specific gravity is reduced to the reference specific gravity is selected as the time when the secondary slime treatment is started.

2次スライム処理は、図3で示すように、孔底に堆積したスライムを安定液2とともにスライム処理装置4にて吸引し、地上に排出する。このとき、孔底近傍に存在する安定液2の吸引と同時に、安定液供給管5を介して吸引した安定液2と同量の安定液2を追加供給し、掘削孔1内における安定液2の液面を常に一定に保持する。   In the secondary slime treatment, as shown in FIG. 3, the slime accumulated on the bottom of the hole is sucked together with the stabilizing solution 2 by the slime treatment device 4 and discharged to the ground. At this time, at the same time as the stable liquid 2 existing near the bottom of the hole is sucked, the stable liquid 2 in the same amount as the sucked stable liquid 2 via the stable liquid supply pipe 5 is additionally supplied, and the stable liquid 2 in the drill hole 1 is supplied. The liquid surface of is always kept constant.

なお、追加供給する安定液2は、新たに安定液2として作液した新液、もしくは地上に排出したスライムを含んだ安定液2を、図示しない安定液プラントにて再生したリサイクル液のいずれを採用したものでもよい。また、スライム処理装置4は、一般に2次スライム処理に採用されているサンドポンプ方式、エアリフト方式、サクションポンプ方式等、掘削孔1の孔底に堆積したスライムを安定液2とともに吸引し、地上に排出できる装置であればいずれを採用してもよい。   The stabilizing liquid 2 to be additionally supplied is either a new liquid newly prepared as the stabilizing liquid 2, or a stabilizing liquid 2 containing slime discharged above the ground, or a recycling liquid regenerated at a stabilizing liquid plant (not shown). The one adopted may be used. In addition, the slime treatment device 4, such as a sand pump method, an air lift method, or a suction pump method, which is generally used for secondary slime treatment, sucks slime accumulated on the bottom of the excavation hole 1 together with the stabilizing solution 2 and puts it on the ground. Any device may be adopted as long as it is a device capable of discharging.

このような2次スライム処理の管理方法は、孔底近傍の安定液2に対して比重と相関関係にある砂分率の測定を一定時間ごとに繰り返し行い、この砂分率が施工現場ごとに定められた管理基準値以下となったところで、2次スライム処理を終了する、という方法である。なお、管理基準値とは、場所打ちコンクリート造の構造物を構築する場合に、施工現場ごとに立てられる施工計画に、安定液の管理方法として記載される数値である。しかし、上述の管理方法では、掘削孔1の孔口部や中間部の砂分率を確認していないため、孔底近傍の安定液2の砂分率が、掘削孔1中の安定液2全体の砂分率を反映しているか否かを評価することができない。   In the management method of such secondary slime treatment, the sand fraction that correlates with the specific gravity is repeatedly measured for the stabilizing solution 2 near the bottom of the hole at regular time intervals, and this sand fraction is measured at each construction site. This is a method of terminating the secondary slime treatment when the value becomes equal to or less than the defined management reference value. In addition, the management reference value is a numerical value described as a management method of the stabilizing liquid in a construction plan established for each construction site when a structure of cast-in-place concrete is constructed. However, in the above management method, since the sand fraction of the hole opening portion and the middle portion of the drill hole 1 is not confirmed, the sand fraction ratio of the stabilizing solution 2 near the bottom of the drilling hole is equal to that of the stabilizing solution 2 in the drilling hole 1. It is not possible to evaluate whether it reflects the overall sand content.

一方で、掘削孔1内の安定液2について発明者らは、管理基準値以下まで低減した孔底近傍の安定液2の砂分率と同一もしくは近似する数値まで、孔口近傍における安定液2の砂分率が低減すると、掘削孔1内の安定液2全体について、その砂分率を管理基準値以下とすることができ、これに伴って時間の経過とともに沈降する可能性の高い砂分を大幅に低減した状態とすることが可能となる、との知見を得ている。   On the other hand, with regard to the stabilizing liquid 2 in the drill hole 1, the inventors have found that the stabilizing liquid 2 in the vicinity of the hole mouth has a value equal to or close to the sand fraction of the stabilizing liquid 2 in the vicinity of the hole bottom, which has been reduced to the control reference value or less. If the sand content ratio of the sand is reduced, the sand content of the entire stabilizing liquid 2 in the drill hole 1 can be set to be equal to or lower than the control reference value, and accordingly, the sand content that is likely to settle with the passage of time. We have obtained the knowledge that it is possible to reduce the amount of noise significantly.

そこで、本実施の形態では、孔底近傍の安定液2だけでなく掘削孔1内全体の安定液2中の砂分率を把握し、図2(b)の深度と砂分率の関係を示すグラフのように、2次スライム処理終了後(時点t3)の安定液2において、砂分率が深度方向に一様な状態となるよう、以下に示す2次スライム処理の管理方法を採用する。   Therefore, in the present embodiment, not only the stabilizer 2 near the bottom of the hole but also the sand ratio in the stabilizer 2 in the entire drill hole 1 is grasped, and the relationship between the depth and the sand ratio in FIG. As shown in the graph, in the stabilizing solution 2 after the completion of the secondary slime treatment (time point t3), the following secondary slime treatment management method is adopted so that the sand content becomes uniform in the depth direction. ..

本実施の形態における2次スライム処理の管理方法は、2次スライム処理の管理として現在実施されている、孔底近傍の安定液2に対して砂分率の測定を一定時間ごとに繰り返し行い、この砂分率が施工現場ごとに定められた管理基準値以下となることを確認する工程(以下、従来工程という)を実施した上で、第1の実施の形態もしくは第2の実施の形態で示す工程を追加して行うものである。   The management method of the secondary slime treatment in the present embodiment is a method that is currently implemented as the management of the secondary slime treatment, in which the sand fraction is repeatedly measured for the stabilizing solution 2 near the bottom of the hole at regular intervals, In the first embodiment or the second embodiment, after performing a step (hereinafter, referred to as a conventional step) of confirming that the sand content ratio is equal to or less than the management reference value set for each construction site The steps shown are added.

〈第1の実施の形態〉
本実施の形態の2次スライム処理の管理方法では、孔底近傍の安定液2の砂分率を測定する従来工程に追加して、少なくとも孔口近傍の安定液2の砂分率の測定を行い、孔口近傍の安定液2の砂分率が同時刻に測定した孔底近傍の安定液2の砂分率と同一もしくは近似する数値となることを確認する工程を実施する。そして、孔底近傍の安定液2の砂分率が施工現場ごとに定められた管理基準値以下となることが確認され、かつ、孔口近傍の安定液2の砂分率が、同時刻に測定した孔底近傍の安定液2の砂分率と同一もしくは近似する数値となったことが確認されるまで、2次スライム処理を継続して行う。
<First Embodiment>
In the management method of the secondary slime treatment of the present embodiment, in addition to the conventional step of measuring the sand fraction of the stabilizer 2 near the bottom of the hole, the sand fraction of the stabilizer 2 at least near the mouth of the hole is measured. Then, the step of confirming that the sand fraction of the stabilizing solution 2 near the hole mouth is the same as or close to the sand fraction of the stabilizing solution 2 near the hole bottom measured at the same time is carried out. Then, it was confirmed that the sand content ratio of the stabilizing solution 2 near the hole bottom was equal to or less than the control reference value set for each construction site, and the sand content rate of the stabilizing solution 2 near the hole mouth was the same time. The secondary slime treatment is continuously performed until it is confirmed that the measured value is the same as or close to the sand fraction of the stabilizing solution 2 near the hole bottom.

なお、砂分率の測定は、例えば図3で示すように、孔口近傍と孔底近傍にサンプラー61、62を設置し、一定時間ごとにサンプルを採取して地上にて測定する定点測定を行うとよい。孔口近傍に設置するサンプラー61は、先に述べた2次スライム処理を開始する時刻を選定するべく比重測定を行った特定深度と同一の深度に設定するとよい。また、孔底近傍に設置するサンプラー62は、従来工程にて砂分率を測定する際に、施工現場ごとで立てられる施工計画に安定液の管理方法として定められた深度に設定する。   In addition, as shown in FIG. 3, for example, the measurement of the sand content is performed by fixed-point measurement in which samplers 61 and 62 are installed near the mouth of the hole and near the bottom of the hole, and samples are taken at regular intervals and measured on the ground. Good to do. The sampler 61 installed near the hole mouth may be set to the same depth as the specific depth at which the specific gravity was measured in order to select the time to start the above-described secondary slime treatment. Further, the sampler 62 installed near the bottom of the hole is set to the depth defined as the stabilizing solution management method in the construction plan established at each construction site when measuring the sand content in the conventional process.

こうすると、コンクリートの打設前に実施する、鉄筋かごを掘削孔1内に建込むとともにトレミー管を挿入するといった作業に手間を要した場合や、不慮の事態によりコンクリートの打設前に大幅な時間を要した場合にも、コンクリートの打設直前時における掘削孔1の孔底に、スライムの堆積をほぼ生じない。これにより、安定液2を長時間静置した場合であっても、従来行われていた、孔底近傍における安定液2を撹拌しスライムを拡散させた上で、コンクリートを打設するといった煩雑な作業を行うことなく、構築後の場所打ちコンクリート杭に対して、スライムに起因する先端支持力の低下を抑制することが可能となる。   If this is done, it will take a lot of time before the concrete is placed, such as when the work is carried out before the concrete is placed, when the reinforced cage is installed in the excavation hole 1 and the tremie pipe is inserted, or due to unforeseen circumstances, a large amount of work is needed before the concrete is placed. Even when it takes a long time, slime is hardly deposited on the hole bottom of the excavation hole 1 immediately before placing concrete. As a result, even when the stabilizing solution 2 is allowed to stand for a long time, it is complicated to stir the stabilizing solution 2 in the vicinity of the bottom of the hole to diffuse the slime and then to pour concrete, which is conventionally done. With respect to the cast-in-place concrete pile after construction, it is possible to suppress the decrease in the tip supporting force due to slime without performing the work.

また、2次スライム処理終了後の安定液2は、掘削孔内全域の砂分率が一様に管理された状態にあるため、安定液が打設中のコンクリートの流動性を損なって巻き込まれるといったコンクリート打設時の置換不良を生じることがなく、高品質の現場打ちコンクリート杭を構築することが可能となる。   In addition, since the stabilizing liquid 2 after the secondary slime treatment is in a state where the sand content ratio in the entire area of the excavation hole is uniformly controlled, the stabilizing liquid 2 impairs the fluidity of the concrete during pouring and is involved. It is possible to construct high quality cast-in-place concrete piles without causing replacement failure during concrete pouring.

なお、孔口近傍の安定液2の砂分率が、同時刻に測定した孔底近傍の安定液2の砂分率と近似する数値となったことの判定方法はいずれでもよいが、例えば、安定液2の配合や作液時の性状、地盤条件や施工条件等を考慮した上で許容範囲を設定する。そして、孔口近傍の安定液2の砂分率と同時刻に測定した孔底近傍の安定液2の砂分率との差が、設定した許容範囲内に収まるか否かで判定してもよい。   Any method may be used to determine that the sand fraction of the stabilizing solution 2 near the hole mouth has become a value close to the sand fraction of the stabilizing solution 2 near the hole bottom measured at the same time. The allowable range is set after considering the composition of Stabilizer 2, properties during preparation, ground conditions and construction conditions. Then, the difference between the sand fraction of the stabilizing solution 2 near the hole mouth and the sand fraction of the stabilizing solution 2 near the bottom of the hole measured at the same time can be determined by whether or not it falls within the set allowable range. Good.

〈第2の実施の形態〉
先にも述べたように、比重と砂分率は相関関係にあることから、第2の実施の形態では、図2(a)の深度と比重の関係を示すグラフのように、2次スライム処理終了後(時点t3)の安定液2において、比重が深度方向に一様な状態となるよう、2次スライム処理の管理方法に砂分率と比重を用いる。
<Second Embodiment>
As described above, since the specific gravity and the sand content have a correlation, in the second embodiment, as shown in the graph showing the relationship between the depth and the specific gravity in FIG. After the completion of the treatment (time t3), the sand fraction and the specific gravity are used in the management method of the secondary slime treatment so that the specific gravity becomes a uniform state in the depth direction.

具体的には、孔底近傍の安定液2の砂分率を測定する従来工程に追加して、孔底近傍の安定液2の比重と孔口近傍の安定液2の比重の測定を行い、同時刻に測定した両者の比重が、施工現場ごとで定められた管理基準値の範囲内に収まることを確認する工程を実施する。そして、孔底近傍の安定液2の砂分率が管理基準値以下になることが確認され、かつ、孔口近傍の安定液2の比重と同時刻に測定した孔底近傍の安定液2の比重がともに、管理基準値の範囲内に収まったことが確認されるまで、2次スライム処理を継続して行う。   Specifically, in addition to the conventional process of measuring the sand fraction of the stabilizing solution 2 near the hole bottom, the specific gravity of the stabilizing solution 2 near the hole bottom and the specific gravity of the stabilizing solution 2 near the hole mouth are measured, A process is carried out to confirm that the specific gravities of both measured at the same time are within the range of the management standard values set for each construction site. Then, it was confirmed that the sand content ratio of the stabilizing solution 2 near the hole bottom was equal to or lower than the control reference value, and the specific gravity of the stabilizing solution 2 near the hole bottom measured at the same time as the specific gravity of the stabilizing solution 2 near the hole mouth. The secondary slime treatment is continuously performed until it is confirmed that both the specific gravities are within the control standard values.

なお、比重の測定は第1の実施の形態と同様な深度位置で、孔口近傍と孔底近傍にサンプラー61、62を設置し、一定時間ごとにサンプルを採取して地上にて測定する定点測定を行うとよい。   The specific gravity is measured at the same depth position as in the first embodiment, and the samplers 61 and 62 are installed near the hole mouth and the hole bottom, and samples are taken at regular intervals to measure on the ground. It is good to measure.

こうすると、第1の実施の形態で示した管理方法と同様に、2次スライム処理の終了後からコンクリートの打設直前までに多大な時間を要した場合にも、掘削孔1の孔底にスライムの堆積をほぼ生じることがなく、コンクリート打設時の置換不良を生じることもない。また、掘削孔内全域の比重が一様に管理された状態にあるため、コンクリートの打設直前時まで、孔壁の崩落を安定して抑制することが可能となる。   By doing this, similarly to the management method shown in the first embodiment, even if a great amount of time is required from the end of the secondary slime treatment to immediately before placing concrete, the bottom of the excavation hole 1 is Almost no slime deposition occurs, and no defective replacement occurs during concrete pouring. Further, since the specific gravity of the entire area of the excavation hole is uniformly controlled, it is possible to stably suppress the collapse of the hole wall until just before placing concrete.

さらに、2次スライム処理の管理方法は、砂分率だけでなく比重を取り入れることから、施工現場で地盤条件のことなる掘削孔1ごとで、掘削孔1内全体の安定液2が良好な性状を有しているか否かの判定を行うことが可能となる。したがって、例えば、孔底近傍および孔口近傍の安定液2の両者の比重が、あらかじめ設定した時刻を経過しても、管理基準値の範囲内に収まらない場合には、掘削孔1内の安定液2を全量入れ替えるというように、良液置換の必要性を判断する指標とすることも可能となる。   Furthermore, since the management method of the secondary slime treatment incorporates not only the sand content but also the specific gravity, the stable liquid 2 in the entire drilling hole 1 has good properties for each drilling hole 1 which has different ground conditions at the construction site. It is possible to determine whether or not the Therefore, for example, when the specific gravity of both the stabilizing liquid 2 near the hole bottom and near the hole mouth does not fall within the range of the management reference value even after the preset time, the stability inside the drill hole 1 is stabilized. It is also possible to use it as an index to judge the necessity of good liquid replacement, such as replacing all the liquid 2.

本発明における2次スライム処理の管理方法は、上記実施形態に限定されるものではなく、本発明の趣旨を逸脱しない範囲で種々の変更が可能である。   The management method of the secondary slime treatment in the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

例えば、本実施の形態では、孔底近傍および孔口近傍の2地点にて砂分率および比重を測定したが、これらに追加して掘削孔1の深度方向に異なる位置に複数の測定点を設けてもよい。   For example, in the present embodiment, the sand fraction and the specific gravity are measured at two points near the hole bottom and the hole mouth. In addition to these, a plurality of measurement points are provided at different positions in the depth direction of the drill hole 1. It may be provided.

また、砂分率の測定方法は、電気比抵抗センサを用いる方法や砂分測定器を用いる方法等いずれを採用してもよく、同様に、比重の測定方法も、マッドバランスを用いる方法や浮き子式比重計を用いる方法等いずれを採用してもよい。このように、掘削孔1の深度方向に異なる位置に複数の設置された測定点の安定液2について、同時刻の砂分率および比重を測定できる方法であれば、原位置にて測定する方法もしくはサンプルを採取して地上にて測定する方法のいずれの測定方法を用いてもよい。   The method for measuring the sand content may be either a method using an electrical resistivity sensor or a method using a sand content measuring instrument. Similarly, the specific gravity is also measured by a method using a mud balance or a float. Any method such as using a slave hydrometer may be adopted. As described above, as long as it is a method capable of measuring the sand fraction and the specific gravity at the same time with respect to the stabilizing liquid 2 at a plurality of measurement points installed at different positions in the depth direction of the drill hole 1, a method of measuring at the original position Alternatively, any measuring method of collecting a sample and measuring on the ground may be used.

さらに、サンプルを採取するにあたり、孔底近傍の安定液2については、サンプラーを用いて採取する方法、スライム処理装置4から排出される安定液2を採取する方法のいずれを採用してもよい。   Further, in collecting the sample, for the stabilizing solution 2 near the hole bottom, either a method of collecting using the sampler or a method of collecting the stabilizing solution 2 discharged from the slime treatment device 4 may be adopted.

また、本実施の形態では、2次スライム処理の終了後に鉄筋かごの建込みを行う方法を示したが、鉄筋かごの建込みを行った後、2次スライム処理を実施する工法に、2次スライム処理の管理方法を採用してもよい。   In addition, in the present embodiment, the method of installing the reinforcing bar car after the completion of the secondary slime treatment has been described. However, after the installation of the reinforcing bar car, the method of performing the secondary slime process is applied to the secondary method. A slime treatment management method may be adopted.

1 掘削孔
2 安定液
3 ケーシング
4 スライム処理装置
5 安定液供給管
61 サンプラー
62 サンプラー
7 表層
8 支持層
1 Drilling Hole 2 Stabilizer 3 Casing 4 Slime Treatment Device 5 Stabilizer Supply Pipe 61 Sampler 62 Sampler 7 Surface Layer 8 Support Layer

Claims (2)

安定液を満たした掘削孔にて1次スライム処理および2次スライム処理を実施した後、前記掘削孔にコンクリートを打設して場所打ちコンクリート造の構造物を構築する方法における、2次スライム処理の管理方法であって、
1次スライム処理後に安定液を所定時間静置して、浮遊していた沈降速度の遅い砂分の沈降が進んだところで開始し、
孔底近傍に設置したサンプラーから採取したサンプルによる、安定液の砂分率の定点測定を一定時間ごとに繰り返し行い、前記孔底近傍の安定液の砂分率が、施工現場ごとに定められた管理基準値以下となることを確認する工程と、
少なくとも孔口近傍に設置したサンプラーから採取したサンプルによる、安定液の砂分率の定点測定を行い、同時刻に測定した孔底近傍の安定液の砂分率と同一もしくは近似する数値となることを確認する工程と、を備え、
両工程の確認が終了するまで、前記2次スライム処理を継続することを特徴とする2次スライム処理の管理方法。
Secondary slime treatment in a method for constructing a cast-in-place concrete structure by performing primary slime treatment and secondary slime treatment in a drill hole filled with a stabilizing solution and then placing concrete in the drill hole Management method of
After the primary slime treatment, the stabilizing solution was allowed to stand for a predetermined period of time, and started when the sedimentation of the suspended sand with a slow sedimentation rate proceeded,
A fixed point measurement of the sand fraction of the stabilizing solution by a sample taken from a sampler installed near the bottom of the hole was repeated at regular intervals, and the sand fraction of the stabilizing solution near the hole bottom was determined for each construction site. The process of confirming that it is below the control standard value,
Perform a fixed point measurement of the sand fraction of the stabilizing solution at least with a sample collected from a sampler installed near the mouth of the hole, and obtain a value that is the same as or close to the sand fraction of the stabilizing solution near the bottom of the hole measured at the same time. And a step of confirming
A method for managing a secondary slime treatment, characterized in that the secondary slime treatment is continued until confirmation of both steps is completed.
安定液を満たした掘削孔にて1次スライム処理および2次スライム処理を実施した後、前記掘削孔にコンクリートを打設して場所打ちコンクリート造の構造物を構築する方法における、2次スライム処理の管理方法であって、
1次スライム処理後に安定液を所定時間静置して浮遊していた沈降速度の遅い砂分の沈降が進んだところで開始し、
孔底近傍に設置したサンプラーから採取したサンプルによる、安定液の砂分率の定点測定を一定時間ごとに繰り返し行い、前記孔底近傍の安定液の砂分率が施工現場ごとに定められた管理基準値以下となることを確認する工程と、
少なくとも孔底近傍の安定液の比重と孔口近傍の安定液の比重の定点測定を、孔底近傍及び孔口近傍に設置したサンプラーから採取したサンプルにより行い、同時刻に測定した両者の比重が、施工現場ごとに定められた管理基準値の範囲内に収まることを確認する工程と、を備え、
両工程の確認が終了するまで、前記2次スライム処理を継続することを特徴とする2次スライム処理の管理方法。
Secondary slime treatment in a method for constructing a cast-in-place concrete structure by performing primary slime treatment and secondary slime treatment in a drill hole filled with a stabilizing solution and then placing concrete in the drill hole Management method of
After the primary slime treatment, the stabilizing solution was allowed to stand for a predetermined period of time and started when sedimentation of sand with a slow sedimentation rate progressed,
A fixed point measurement of the sand fraction of the stabilizing solution by a sample taken from a sampler installed near the bottom of the hole is repeated every certain time, and the sand fraction of the stabilizing solution near the hole bottom is controlled by the construction site. A step of confirming that it is below the reference value,
At least the specific gravity of the stable liquid near the bottom of the hole and the specific gravity of the stable liquid near the mouth of the hole were measured with a sample taken from a sampler installed near the bottom of the hole and near the mouth of the hole. , A step of confirming that it falls within the range of the management reference value set for each construction site,
A method for managing a secondary slime treatment, characterized in that the secondary slime treatment is continued until confirmation of both steps is completed.
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