JP2019132097A - Measurement device for scp method, casing pipe for scp method, and construction management method of scp method - Google Patents

Measurement device for scp method, casing pipe for scp method, and construction management method of scp method Download PDF

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JP2019132097A
JP2019132097A JP2018017087A JP2018017087A JP2019132097A JP 2019132097 A JP2019132097 A JP 2019132097A JP 2018017087 A JP2018017087 A JP 2018017087A JP 2018017087 A JP2018017087 A JP 2018017087A JP 2019132097 A JP2019132097 A JP 2019132097A
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pile
sand pile
construction
casing pipe
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JP6985948B2 (en
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保弘 吉岡
Yasuhiro Yoshioka
保弘 吉岡
上野　一彦
Kazuhiko Ueno
一彦 上野
哲平 秋本
Teppei Akimoto
哲平 秋本
辰哉 江守
Tatsuya Emori
辰哉 江守
タング タン ビン グエン
Tang Thanh Binh Nguyen
タング タン ビン グエン
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Penta Ocean Construction Co Ltd
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Abstract

To provide a measurement device for SCP method which can measure a diameter of a sand pipe during construction by an SCP method and can also measure a sand pipe strength, a casing pipe for SCP method having the measurement device, and a construction management method of SCP method using the measurement device.SOLUTION: A measurement device 20 includes a penetration rod 11 which is arranged at the center of a lower inner periphery of a casing pipe 10 and is extensible in an axial direction, an actuator 15A for projecting or evacuating the penetration rod, and elastic wave transmission/reception parts 13 and 14 provided on the tip vicinity of the penetration rod, projects the penetration rod from an upper end face SS of a sand pipe SC established on the ground by the casing pipe 10 with the actuator, penetrates the penetration rod into the sand pipe, allows the elastic wave transmission/reception parts to transmit elastic waves T1 and T2 in a radial direction of the sand pipe and to receive reflection waves R1 and R2, and thereby measures a diameter of the sand pipe.SELECTED DRAWING: Figure 3

Description

本発明は、SCP工法による施工中に砂杭の形状を計測可能なSCP工法用計測装置、この計測装置を有するSCP工法用ケーシングパイプおよびこの計測装置を用いたSCP工法の施工管理方法に関する。   The present invention relates to a measuring device for SCP method capable of measuring the shape of a sand pile during construction by the SCP method, a casing pipe for SCP method having the measuring device, and a construction management method of the SCP method using this measuring device.

サンドコンパクションパイル工法（以下、「SCP工法」ともいう。）は、振動を用いて砂または類似の材料をケーシングパイプ（鋼製中空管）により軟弱地盤に圧入することにより、締め固められた大径の砂杭（サンドコンパクションパイル）を軟弱地盤内に造成する地盤改良工法である。SCP工法における品質および出来形の管理基準は、たとえば、港湾工事共通仕様書で規定され、以下の通りである。
・品質管理基準：砂（材質：外観、種類、品質及び粒度、シルト以下の細粒分含有率）
・出来形管理基準：サンドコンパクションパイル（位置、天端高・先端深度、砂の投入量、盛上り量） The sand compaction pile method (hereinafter also referred to as the “SCP method”) is a compact structure that is compacted by pressing sand or a similar material into the soft ground using a casing pipe (steel hollow tube) using vibration. This is a ground improvement method in which sand piles with a diameter (sand compaction pile) are created in soft ground. The quality and control standards for SCP construction methods are stipulated, for example, in the port construction common specifications, and are as follows.
-Quality control standards: sand (material: appearance, type, quality and particle size, fine particle content below silt)
・ Finished form management standards: Sand compaction pile (position, top height / tip depth, sand input, climax)

特開2009-243057号公報JP 2009-243057

SCP工法による軟弱粘性土における地盤改良の目的として、締め固めた砂杭と軟弱粘性土からなる複合地盤を形成し、上載荷重に対する支持力の増強、ドレーン効果を含めた地盤全体の剛性の増加、すべり抵抗の増加、沈下の低減を図ること等が挙げられる。しかし、従来の管理方法で施工中の管理は砂面計と深度計を用いて投入砂の体積を確認するもので、砂杭の形状を調査する方法がない。このため、強度に影響する砂杭の径が、設計値に通りになっているか分からない。   For the purpose of ground improvement in soft-viscous soil by the SCP method, a composite ground consisting of compacted sand piles and soft-viscous soil is formed, increasing the bearing capacity against the overload, increasing the rigidity of the entire ground including the drain effect, For example, increasing slip resistance and reducing settlement. However, the management during construction by the conventional management method is to check the volume of the input sand using a sand level meter and depth meter, and there is no method for investigating the shape of the sand pile. For this reason, it is not known whether the diameter of the sand pile that affects the strength conforms to the design value.

また、砂杭強度については品質および出来形の管理基準がないのが現状であり、次の問題点がある。
(1)従来の管理方法では砂杭の強度は施工後に貫入試験を行うまで分からず、施工中に砂杭強度を直接計測し確認することはできない。
(2)砂杭の強度確認として砂杭造成後に調査ボーリングを行っているが、全数調査ではない。
(3)調査ボーリングは造成した砂杭中にボーリングロッドを貫入するため砂杭密度に影響を及ぼす恐れがある。
(4)事後調査時に設計強度に満たない箇所が確認されても砂杭造成後の手直しをすることが非常に難しい。 In addition, there are no quality and control standards for sand pile strength, and there are the following problems.
(1) With conventional management methods, the strength of sand piles is not known until a penetration test is performed after construction, and it is not possible to directly measure and confirm sand pile strength during construction.
(2) Although the survey boring is conducted after the sand pile construction to confirm the strength of the sand pile, it is not a complete survey.
(3) The survey boring penetrates the boring rod into the constructed sand pile, which may affect the sand pile density.
(4) It is very difficult to rework after sand pile construction even if a location that does not meet the design strength is confirmed during the ex-post survey.

特許文献１は、ケーシングパイプの上端部に設置された圧入シリンダの押込み圧力、ウインチの吊り荷重、ケーシングパイプの貫入量、砂杭打込み機の作業時間及びケーシングパイプの回転トルクを夫々検出し、検出値に基づいて地盤貫入部もしくは砂杭の応力を算出し、算出値が予め定めた目標値になるようにケーシングパイプの貫入又は砂杭の造成を行うようにしたSCP工法を開示するが、SCP工法による砂杭の径等の形状を評価可能なものではない。また、砂杭の強度（応力）を推定する方法も曖昧である。   Patent Document 1 detects and detects the indentation pressure of the press-fit cylinder installed at the upper end of the casing pipe, the suspension load of the winch, the penetration amount of the casing pipe, the working time of the sand pile driving machine, and the rotational torque of the casing pipe. The SCP method is disclosed in which the stress of the ground penetration or sand pile is calculated based on the value, and the casing pipe is penetrated or the sand pile is created so that the calculated value becomes a predetermined target value. It is not possible to evaluate the shape of sand piles by the method. The method for estimating the strength (stress) of sand piles is also ambiguous.

本発明は、上述のような従来技術の問題に鑑み、SCP工法による施工中に砂杭の径を計測可能でさらに砂杭強度を計測可能なSCP工法用計測装置、この計測装置を有するSCP工法用ケーシングパイプおよびこの計測装置を用いたSCP工法の施工管理方法を提供することを目的とする。   The present invention, in view of the problems of the prior art as described above, can measure the diameter of the sand pile during construction by the SCP method, and can further measure the strength of the sand pile, SCP method having this measuring device It aims at providing the construction management method of the SCP method using the casing pipe for this and this measuring device.

上記目的を達成するためのサンドコンパクションパイル工法用計測装置は、サンドコンパクションパイル工法用ケーシングパイプの下部内周の中心に配置され軸方向に伸縮可能な貫入ロッドと、前記貫入ロッドを突出させまた退避させるためのアクチュエータと、前記貫入ロッドの先端近傍に設けられた弾性波送受信部と、を備え、前記貫入ロッドを、前記ケーシングパイプで地盤に造成された砂杭の上端面から前記アクチュエータにより突出させて砂杭内部に貫入させ、前記弾性波送受信部が弾性波を前記砂杭の半径方向に送信し、その反射波を受信することで、前記砂杭の径を計測するものである。   A measuring device for sand compaction pile method for achieving the above object is a penetrating rod arranged in the center of the lower inner periphery of a casing pipe for sand compaction pile method and capable of extending and retracting the penetrating rod. And an elastic wave transmitting / receiving unit provided in the vicinity of the tip of the penetrating rod, and the penetrating rod protrudes from the upper end surface of the sand pile formed on the ground with the casing pipe by the actuator. The elastic wave transmitting / receiving unit transmits the elastic wave in the radial direction of the sand pile and receives the reflected wave, thereby measuring the diameter of the sand pile.

このSCP工法用計測装置によれば、貫入ロッドをケーシングパイプで地盤に造成された砂杭の上端面から砂杭内部に貫入させ、貫入ロッドの先端近傍の弾性波送受信部が弾性波を砂杭の半径方向に送信し、砂杭と地盤との境界の速度変化部で反射した反射波を受信することで、送信から受信までの時間差に基づいて砂杭の径を計測することができる。なお、貫入ロッドは、計測後、アクチュエータにより貫入位置から上方に退避させることで、ケーシングパイプによる砂杭造成の邪魔にならず、また、砂杭造成による破損を防止できる。   According to this SCP method measuring device, the penetrating rod is penetrated into the sand pile from the upper end surface of the sand pile formed on the ground with a casing pipe, and the elastic wave transmitting / receiving unit near the tip of the penetrating rod transmits the elastic wave to the sand pile. The diameter of the sand pile can be measured based on the time difference from the transmission to the reception by receiving the reflected wave reflected at the speed change portion at the boundary between the sand pile and the ground. The penetrating rod is retracted upward from the penetrating position by an actuator after measurement, so that it does not obstruct sand pile formation by the casing pipe, and damage due to sand pile formation can be prevented.

上記SCP工法用計測装置において前記弾性波送受信部から弾性波を所定の半径方向およびその半径方向と180度異なる半径方向にそれぞれ送信し、各反射波を受信し、前記砂杭の径を計測することで、砂杭の直径を精度よく計測できる。   In the SCP construction method measuring device, an elastic wave is transmitted from the elastic wave transmitting / receiving unit in a predetermined radial direction and a radial direction 180 degrees different from the radial direction, each reflected wave is received, and the diameter of the sand pile is measured. Thus, the diameter of the sand pile can be accurately measured.

また、前記弾性波の発信周波数を変化させながら前記送信および前記受信を行い、前記受信時に測定された最大受信波強度に対応した発信周波数に基づいて前記砂杭の径を計測するように構成してもよい。   Further, the transmission and reception are performed while changing the transmission frequency of the elastic wave, and the diameter of the sand pile is measured based on the transmission frequency corresponding to the maximum received wave intensity measured at the time of reception. May be.

また、前記貫入ロッドの砂杭内部への貫入時の貫入抵抗を測定する荷重計をさらに備え、前記貫入時に測定された貫入抵抗に基づいて前記砂杭の強度を計測するように構成できる。これにより、さらに砂杭強度を計測することができる。   Moreover, the load rod which measures the penetration resistance at the time of penetration of the said penetration rod into the sand pile inside is further provided, and it can comprise so that the intensity | strength of the said sand pile may be measured based on the penetration resistance measured at the time of the penetration. Thereby, the sand pile strength can be further measured.

上記目的を達成するためのサンドコンパクションパイル工法用ケーシングパイプは、地盤に砂杭を造成するサンドコンパクションパイル工法に用いられるケーシングパイプであって、上述のサンドコンパクションパイル工法用計測装置を備える。このケーシングパイプによれば、SCP工法により砂杭を造成し、この砂杭の造成途中や造成後に砂杭の径および／または強度を計測することができる。   The casing pipe for sand compaction pile method for achieving the above object is a casing pipe used in the sand compaction pile method for forming a sand pile on the ground, and includes the above-described measuring device for sand compaction pile method. According to this casing pipe, a sand pile can be created by the SCP method, and the diameter and / or strength of the sand pile can be measured during and after the construction of the sand pile.

上記目的を達成するためのSCP工法の施工管理方法は、上述の計測装置を用いて、SCP工法により地盤に砂杭を造成する施工を管理する方法であって、前記砂杭の造成途中または造成後に前記上端面から前記貫入ロッドを砂杭内部に貫入させ、前記弾性波送受信部での前記弾性波の送信および前記反射波の受信により前記砂杭の径を計測し、前記計測値に基づいて前記砂杭の形状を評価し、前記評価結果に基づいてSCP工法の施工を管理するものである。   The construction management method of the SCP method for achieving the above object is a method of managing the construction of creating a sand pile on the ground by the SCP method using the above-described measuring device, and is in the middle of or during construction of the sand pile. Later, the penetrating rod is penetrated into the sand pile from the upper end surface, and the diameter of the sand pile is measured by transmitting the elastic wave and receiving the reflected wave in the elastic wave transmitting / receiving unit, and based on the measured value The shape of the sand pile is evaluated, and the construction of the SCP method is managed based on the evaluation result.

このSCP工法の施工管理方法によれば、砂杭形状の評価工程を組み入れることで、砂杭の径の計測値と設計値（目標値）とから砂杭形状を砂杭の造成途中または造成後に評価でき、また、砂杭の全数について砂杭形状を評価でき、さらに、砂杭形状の評価結果に応じて砂の再投入や締め固めを行うことができる。このため、地盤に造成される砂杭の形状品質に関する施工管理を確実に行うことができ、高品質な砂杭を造成できる。   According to the construction management method of this SCP method, by incorporating a sand pile shape evaluation process, the sand pile shape can be changed during or after sand pile formation from the measured value and design value (target value) of the sand pile diameter. The sand pile shape can be evaluated with respect to the total number of sand piles, and sand can be recharged and compacted according to the evaluation result of the sand pile shape. For this reason, the construction management regarding the shape quality of the sand pile formed on the ground can be reliably performed, and a high quality sand pile can be created.

上記目的を達成するためのもう１つのSCP工法の施工管理方法は、上述の荷重計をさらに備える計測装置を用いて、SCP工法により地盤に砂杭を造成する施工を管理する方法であって、前記砂杭の造成途中または造成後に前記上端面から前記貫入ロッドを砂杭内部に貫入させ、前記貫入時に前記荷重計により貫入抵抗を測定し、前記測定された貫入抵抗に基づいて前記砂杭の強度を求めて評価し、前記評価結果に基づいてサンドコンパクションパイル工法の施工を管理するものである。   Another SCP construction method management method for achieving the above object is a method of managing construction for creating a sand pile on the ground by the SCP method using a measuring device further comprising the above-described load meter, During or after the formation of the sand pile, the penetrating rod is penetrated into the sand pile from the upper end surface, and the penetration resistance is measured by the load meter at the time of penetration, and the sand pile is measured based on the measured penetration resistance. The strength is obtained and evaluated, and the construction of the sand compaction pile method is managed based on the evaluation result.

このSCP工法の施工管理方法によれば、砂杭強度の評価工程を組み入れることで、砂杭強度の計測値と設計値（目標値）とから砂杭強度を砂杭の造成途中または造成後に評価でき、また、砂杭の全数について砂杭強度を評価でき、さらに、砂杭強度の評価結果に応じて砂の再投入や締め固めを行うことができる。このため、地盤に造成される砂杭の強度品質に関する施工管理を確実に行うことができ、高品質な砂杭を造成できる。   According to the construction management method of this SCP method, the sand pile strength is evaluated during or after the sand pile is built from the measured value and the design value (target value) of the sand pile strength by incorporating the sand pile strength evaluation process. In addition, the sand pile strength can be evaluated with respect to the total number of sand piles, and sand can be re-input or compacted according to the evaluation result of the sand pile strength. For this reason, the construction management regarding the strength quality of the sand pile created on the ground can be reliably performed, and a high quality sand pile can be created.

なお、もう１つのサンドコンパクションパイル工法用計測装置は、サンドコンパクションパイル工法用ケーシングパイプの下部内周の中心に配置され軸方向に伸縮可能な貫入ロッドと、前記貫入ロッドを突出させまた退避させるためのアクチュエータと、前記貫入ロッドの砂杭内部への貫入時の貫入抵抗を測定する荷重計と、を備え、前記貫入ロッドを、前記ケーシングパイプで地盤に造成された砂杭の上端面から前記アクチュエータにより突出させて砂杭内部に貫入させ、前記貫入時に前記荷重計により測定された貫入抵抗に基づいて前記砂杭の強度を計測するものである。   Another measuring device for sand compaction pile method is a penetrating rod that is arranged at the center of the lower inner periphery of a casing pipe for sand compaction pile method and that can extend and retract in the axial direction, and projects and retracts the penetrating rod. And a load cell for measuring penetration resistance when the penetration rod penetrates into the sand pile, and the penetration rod is formed from the upper end surface of the sand pile formed on the ground with the casing pipe. And the strength of the sand pile is measured based on the penetration resistance measured by the load meter at the time of penetration.

本発明によれば、SCP工法による施工中に砂杭の径を計測可能でさらに砂杭強度を計測可能なSCP工法用計測装置、この計測装置を有するSCP工法用ケーシングパイプおよびこの計測装置を用いたSCP工法の施工管理方法を提供することができる。   According to the present invention, a measuring device for SCP method capable of measuring the diameter of a sand pile during construction by the SCP method and further measuring the strength of the sand pile, a casing pipe for SCP method having this measuring device, and this measuring device are used. We can provide the construction management method of the existing SCP method.

本実施形態による砂杭の径を計測するための計測装置を備えるSCP工法用ケーシングパイプの要部縦断面図（ａ）およびB-B線方向から見た底面図（ｂ）である。It is the principal part longitudinal cross-sectional view (a) of the casing pipe for SCP construction methods provided with the measuring apparatus for measuring the diameter of the sand pile by this embodiment, and the bottom view (b) seen from the BB line direction. 本実施形態による砂杭の径・強度を計測するための計測システムを概略的に示すブロック図である。It is a block diagram which shows roughly the measuring system for measuring the diameter and intensity | strength of the sand pile by this embodiment. 図１のSCP工法用ケーシングパイプで造成した砂杭の径を弾性波で計測する様子を示す要部縦断面図（ａ）およびBB-BB線方向から見た底面図（ｂ）である。It is the principal part longitudinal cross-sectional view (a) which shows a mode that the diameter of the sand pile formed with the casing pipe for SCP method of FIG. 1 is measured with an elastic wave, and the bottom view (b) seen from the BB-BB line direction. 本実施形態による砂杭の形状および強度を計測し評価し施工管理をする工程（Ｓ０１〜Ｓ０７）を説明するためのフローチャートである。It is a flowchart for demonstrating the process (S01-S07) which measures and evaluates the shape and intensity | strength of the sand pile by this embodiment, and performs construction management. 図１の弾性波送受信部１３，１４から送信される弾性波の発信周波数を変化させたときの受信波強度の変化を概略的に示すグラフである。It is a graph which shows roughly the change of the received wave intensity when changing the transmission frequency of the elastic wave transmitted from the elastic wave transmission-and-reception parts 13 and 14 of FIG. 本実施形態による砂杭の造成工程（ａ）〜（ｇ）を示す概略図である。It is the schematic which shows the creation process (a)-(g) of the sand pile by this embodiment. 図６の砂杭造成工程と砂杭形状・強度の評価工程とを含む施工管理工程Ｓ２１〜Ｓ２８を説明するためのフローチャートである。It is a flowchart for demonstrating construction management process S21-S28 including the sand pile formation process of FIG. 6, and the sand pile shape and intensity | strength evaluation process. 図１の貫入ロッド１１のコーン部１２の形状例を示す図である。It is a figure which shows the example of a shape of the cone part 12 of the penetration rod 11 of FIG.

以下、本発明を実施するための形態について図面を用いて説明する。図１は本実施形態による砂杭の径を計測するための計測装置を備えるSCP工法用ケーシングパイプの要部縦断面図（ａ）およびB-B線方向から見た底面図（ｂ）である。   Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view (a) of a main part of a casing pipe for an SCP method equipped with a measuring device for measuring the diameter of a sand pile according to the present embodiment, and a bottom view (b) as viewed from the direction of the line BB.

図１（ａ）（ｂ）のように、SCP工法用ケーシングパイプ１０は、鋼製中空管から構成され、SCP工法により地盤に砂杭を造成するもので、その下部内周の中央部には、砂杭造成中に地盤の粘性土等がケーシングパイプ１０内に流入するのを防ぐために円形状の閉塞板２１が設置され、閉塞板２１を補強する脱落防止用の補強部材２２が十字状に配置されてケーシングパイプ１０の内周面に固定され、また、閉塞板２１および補強部材２２の中心部を上下に貫通するようにして砂杭の径を計測するための計測装置２０が配置されている。   As shown in FIGS. 1 (a) and 1 (b), the casing pipe 10 for the SCP method is composed of a steel hollow tube, and a sand pile is created on the ground by the SCP method. In order to prevent the clayey soil of the ground from flowing into the casing pipe 10 during sand pile formation, a circular blocking plate 21 is installed, and the drop-off prevention reinforcing member 22 that reinforces the blocking plate 21 has a cross shape. And a measuring device 20 for measuring the diameter of the sand pile so as to penetrate vertically through the central portion of the closing plate 21 and the reinforcing member 22 is arranged. ing.

計測装置２０は、ケーシングパイプ１０の下部内周の中心に配置され縦方向（鉛直方向）に伸縮可能な円柱状の貫入ロッド１１と、貫入ロッド１１の上方に位置し貫入ロッド１１を下方に突出させまた上方に退避させるためのアクチュエータ１５Ａと、貫入ロッド１１の先端近傍に設けられた弾性波送受信部１３，１４と、貫入ロッド１１やアクチュエータ１５Ａを収容する円筒状の収容部１６Ａと、を備える。貫入ロッド１１は、その先端が尖った円錐状に構成されたコーン部１２を有し、その砂杭への貫入抵抗を計測することで、砂杭強度を計測することができる。コーン部１２の形状例を図８に示すが、図８の例では、コーン部１２の高さが39.2mm、先端角が30度、直径が20.3mmである。   The measuring device 20 is arranged at the center of the lower inner circumference of the casing pipe 10 and has a cylindrical penetrating rod 11 that can extend and contract in the vertical direction (vertical direction), and is positioned above the penetrating rod 11 and projects the penetrating rod 11 downward. And an actuator 15A for retreating upward, elastic wave transmitting / receiving sections 13 and 14 provided near the tip of the penetrating rod 11, and a cylindrical housing section 16A for housing the penetrating rod 11 and the actuator 15A. . The penetrating rod 11 has a cone portion 12 having a conical shape with a sharp tip, and the sand pile strength can be measured by measuring the penetration resistance into the sand pile. An example of the shape of the cone portion 12 is shown in FIG. 8. In the example of FIG. 8, the height of the cone portion 12 is 39.2 mm, the tip angle is 30 degrees, and the diameter is 20.3 mm.

計測装置２０の収容部１６Ａの上側に位置するアクチュエータ１５Ａは、支持部１８を介して収容部１６Ａの上部で支持され固定されている。また、収容部１６Ａは、その下部に厚肉円筒部１７を有し、厚肉円筒部１７の中心孔１７ａに貫入ロッド１１が円滑に摺動可能なようにシールするシール部１７ｂを介して貫入ロッド１１が上下に移動可能に配置されている。厚肉円筒部１７は、十字状の補強部材２２と円形状の閉塞板２１の中心部を貫通して配置され、補強部材２２に固定されることで、収容部１６Ａの全体がケーシングパイプ１０の下部内周に固定されている。   The actuator 15A located on the upper side of the accommodating portion 16A of the measuring device 20 is supported and fixed on the upper portion of the accommodating portion 16A via the support portion 18. The accommodating portion 16A has a thick cylindrical portion 17 at the lower portion thereof, and penetrates through a seal portion 17b that seals the penetration rod 11 into the central hole 17a of the thick cylindrical portion 17 so that the penetration rod 11 can slide smoothly. The rod 11 is arranged to be movable up and down. The thick cylindrical portion 17 is disposed through the central portion of the cross-shaped reinforcing member 22 and the circular blocking plate 21 and is fixed to the reinforcing member 22, so that the entire accommodating portion 16 </ b> A of the casing pipe 10 is formed. It is fixed to the lower inner circumference.

アクチュエータ１５Ａは、たとえば、水圧ホース１５Ｂが接続されて水圧で作動するシリンダから構成でき、駆動信号に基づいてその作動棒１５ａの出し入れが制御される。アクチュエータ１５Ａの作動棒１５ａはその先端で貫入ロッド１１の上端と連結し、貫入ロッド１１の上端側にロードセル等からなる荷重計１９が配置されている。   The actuator 15A can be constituted by, for example, a cylinder that is connected to a hydraulic hose 15B and is operated by water pressure, and the operation rod 15a is controlled in and out based on a drive signal. The actuating rod 15a of the actuator 15A is connected to the upper end of the penetrating rod 11 at its tip, and a load meter 19 including a load cell is disposed on the upper end side of the penetrating rod 11.

貫入ロッド１１は、ケーシングパイプ１０の内周中心に位置し縦方向（鉛直方向）にアクチェエータ１５の作動で作動棒１５ａにより突出しまた退避することができ、計測時に突出させることで砂杭の上端面から砂杭内部に貫入し、このときの貫入抵抗を荷重計１９により測定できる。また、貫入ロッド１１は、計測後等の非計測時には、アクチュエータ１５Ａにより貫入位置から上方に退避させることで、ケーシングパイプ１０による砂杭造成の邪魔にならず、また、砂杭造成による破損を防止できる。   The penetrating rod 11 is located at the center of the inner periphery of the casing pipe 10 and can be protruded and retracted by the actuating rod 15a in the longitudinal direction (vertical direction) by the operation of the actuator 15. By projecting at the time of measurement, the upper end surface of the sand pile The penetration resistance at this time can be measured by the load meter 19. Further, the penetration rod 11 is not disturbed by sand pipe construction by the casing pipe 10 by being retracted upward from the penetration position by the actuator 15A at the time of non-measurement such as after measurement, and also prevents damage due to sand pile construction. it can.

弾性波送受信部１３，１４は、コーン部１２の上方近傍の円筒面に配置され、たとえば、圧電素子から構成され、砂杭中心軸にある貫入ロッド１１の位置から弾性波を水平方向の砂杭半径方向に送信し、砂杭と地盤との境界の速度変化部で反射した反射波を受信する機能を有する。弾性波送受信部１３はたとえば円周方向０度に位置する場合、弾性波送受信部１４は円周方向１８０度に位置し、互いに弾性波を、砂杭軸を中心にして１８０度反対方向に送信するようになっている。   The elastic wave transmission / reception units 13 and 14 are arranged on a cylindrical surface near the upper portion of the cone unit 12, and are composed of, for example, a piezoelectric element. The elastic wave is transmitted from the position of the penetrating rod 11 on the sand pile central axis in the horizontal direction It has the function of transmitting in the radial direction and receiving the reflected wave reflected by the speed change part at the boundary between the sand pile and the ground. For example, when the elastic wave transmission / reception unit 13 is positioned at 0 ° in the circumferential direction, the elastic wave transmission / reception unit 14 is positioned at 180 ° in the circumferential direction, and transmits elastic waves to each other in the opposite direction by 180 ° around the sand pile axis. It is supposed to be.

なお、弾性波は地盤内を弾性運動により伝播する波動で、弾性波には、振動方向が伝搬方向と一致するＰ波（縦波）と、振動方向が伝搬方向と直交するＳ波（横波）とがあり、Ｐ波はＳ波よりも速く伝播する。弾性波の伝播速度は、土質により変化するが、砂杭の場合、管理された砂を使用するので、ばらつきは少ないと考えられる。   An elastic wave is a wave propagating in the ground by elastic motion. The elastic wave includes a P wave (longitudinal wave) whose vibration direction coincides with the propagation direction and an S wave (transverse wave) whose vibration direction is orthogonal to the propagation direction. The P wave propagates faster than the S wave. The propagation speed of elastic waves varies depending on the soil quality, but in the case of sand piles, it is considered that there is little variation because managed sand is used.

図１（ａ）（ｂ）のように、計測装置２０は、厚肉円筒部１７を含めた収容部１６Ａがケーシングパイプ１０の下部内周の中央部において縦方向に細長く構成される。ケーシングパイプ１０は、上方から供給される砂を下端開口から吐出して砂杭を地盤内に造成するが、ケーシングパイプ１０の下部内周の中央部に閉塞板２１があり、その閉塞板２１のある中央部付近は、砂の流れが少なく、磨耗も少なく、砂の流れを阻害することもほとんどなく、また、閉塞板２１とケーシングパイプ１０を連結する構造部材としての補強部材２２がある。このような中央部の領域に、ケーシングパイプ１０の軸方向に細長い計測装置２０を設置してもケーシングパイプ１０による砂杭造成の支障にはならず、また、その設置も容易である。   As shown in FIGS. 1A and 1B, the measuring device 20 is configured such that the accommodating portion 16 </ b> A including the thick-walled cylindrical portion 17 is elongated in the vertical direction at the central portion of the lower inner periphery of the casing pipe 10. The casing pipe 10 discharges sand supplied from above from the lower end opening to create a sand pile in the ground. The casing pipe 10 has a closing plate 21 at the center of the lower inner periphery of the casing pipe 10. In the vicinity of a certain central portion, there is little sand flow, little wear, little hindrance to the sand flow, and there is a reinforcing member 22 as a structural member for connecting the closing plate 21 and the casing pipe 10. Even if the measuring device 20 elongated in the axial direction of the casing pipe 10 is installed in such a central region, the sand pile formation by the casing pipe 10 is not hindered, and the installation is easy.

次に、本実施形態による砂杭の径・強度の計測システムについて図２を参照して説明する。図２は、本実施形態による砂杭の径・強度を計測するための計測システムを概略的に示すブロック図である。   Next, the diameter / strength measuring system of the sand pile according to the present embodiment will be described with reference to FIG. FIG. 2 is a block diagram schematically showing a measurement system for measuring the diameter and strength of the sand pile according to the present embodiment.

図２のように、計測システム５０は、図１（ａ）のケーシングパイプ１０の下部に配置された計測装置２０の荷重計１９および弾性波送受信部１３，１４と配線Ｌを通して電気接続する接続部５１と、接続部５１と有線で電気接続をする計測側接続部５２と、荷重計１９からの測定信号に基づいて貫入抵抗を計測する荷重計側部５４と、弾性波送受信部１３，１４から弾性波を発信させるための駆動信号を送信する送信部５５と、弾性波送受信部１３，１４で反射波を受信した受信信号を受信する受信部５６と、送信部５５と受信部５６とからの信号に基づいて距離を演算し計測する距離計測部５７と、計測装置２０のアクチュエータ１５Ａを水圧で駆動するための水圧ユニット５９と、水圧ユニット５９に駆動信号を送りアクチュエータ１５Ａを駆動するアクチュエータ駆動部５３と、各部５２〜５７を制御し、また、各種演算をするパーソナルコンピュータ（ＰＣ）から構成される制御部５８と、を備える。   As shown in FIG. 2, the measuring system 50 includes a connecting portion that is electrically connected to the load meter 19 and the elastic wave transmitting / receiving portions 13 and 14 of the measuring device 20 disposed below the casing pipe 10 of FIG. 51, a measurement side connection unit 52 that is electrically connected to the connection unit 51 in a wired manner, a load meter side unit 54 that measures penetration resistance based on a measurement signal from the load meter 19, and the elastic wave transmission / reception units 13 and 14. A transmission unit 55 that transmits a drive signal for transmitting an elastic wave, a reception unit 56 that receives a reception signal received by the elastic wave transmission / reception units 13 and 14, a transmission unit 55, and a reception unit 56 A distance measuring unit 57 that calculates and measures a distance based on the signal, a water pressure unit 59 for driving the actuator 15A of the measuring device 20 with water pressure, and a drive signal is sent to the water pressure unit 59. Actuator 1 Includes an actuator driver 53 for driving the A, controls each unit 52-57 also includes a control unit 58 composed of a personal computer (PC) for various calculations, a.

計測装置２０のアクチュエータ１５Ａ，荷重計１９および弾性波送受信部１３，１４と接続部５１とがケーシングパイプ１０側に設置され、計測側接続部５２とアクチュエータ駆動部５３と荷重計側部５４と送信部５５と受信部５６と距離計測部５７と制御部５８とが、たとえば、施工中のケーシングパイプ１０と離れた作業船の操作室に設置され、水圧ユニット５９が作業船上に設置されることで、計測システム５０により、造成中の砂杭の径および貫入抵抗を計測することができる。   The actuator 15A of the measuring device 20, the load meter 19, the elastic wave transmitting / receiving units 13 and 14, and the connecting portion 51 are installed on the casing pipe 10 side, and the measuring side connecting portion 52, the actuator driving portion 53, the load meter side portion 54 and the transmission are transmitted. The unit 55, the receiving unit 56, the distance measuring unit 57, and the control unit 58 are installed, for example, in the operation room of the work ship away from the casing pipe 10 being constructed, and the hydraulic unit 59 is installed on the work ship. The diameter and penetration resistance of the sand pile under construction can be measured by the measurement system 50.

なお、計測装置２０の各部１３，１４，１９からの信号線やアクチュエータ１５Ａから水圧ユニット５９へ延びる水圧ホース１５Ｂは、閉塞板２１や補強部材２２の中を通してケーシングパイプ１０の外へ導くことができ、さらに、各部１３，１４，１９の信号線を接続部５１に電気接続する配線Ｌや水圧ホース１５Ｂは、たとえば、ケーシングパイプ１０の側面に設けられる空気圧送用配管内を通すようにできる。また、図２の接続部５１と計測側接続部５２とを無線通信で接続するようにしてもよい。   The signal lines from the respective parts 13, 14, 19 of the measuring device 20 and the hydraulic hose 15 </ b> B extending from the actuator 15 </ b> A to the hydraulic unit 59 can be led out of the casing pipe 10 through the blocking plate 21 and the reinforcing member 22. Furthermore, the wiring L and the hydraulic hose 15B that electrically connect the signal lines of the respective parts 13, 14, and 19 to the connection part 51 can be passed through, for example, a pneumatic feed pipe provided on the side surface of the casing pipe 10. Further, the connection unit 51 and the measurement side connection unit 52 of FIG. 2 may be connected by wireless communication.

次に、図１，図２の計測装置・計測システムによる造成中における砂杭の径および砂杭強度の計測方法について図３，図４を参照して説明する。図３は、図１のSCP工法用ケーシングパイプで造成した砂杭の径を弾性波で計測する様子を示す要部縦断面図（ａ）およびBB-BB線方向から見た底面図（ｂ）である。図４は、本実施形態による砂杭の形状および強度を計測し評価し施工管理をする工程（Ｓ０１〜Ｓ０７）を説明するためのフローチャートである。   Next, a method for measuring the diameter of the sand pile and the strength of the sand pile during construction by the measuring device / measurement system of FIGS. 1 and 2 will be described with reference to FIGS. FIG. 3 shows a longitudinal section (a) of the main part showing a state in which the diameter of the sand pile formed by the casing pipe for the SCP method of FIG. 1 is measured by an elastic wave, and a bottom view (b) seen from the direction of the BB-BB line. It is. FIG. 4 is a flowchart for explaining the steps (S01 to S07) of measuring and evaluating the shape and strength of the sand pile according to this embodiment and managing the construction.

図３（ａ）（ｂ）のように、ケーシングパイプ１０により粘性土等からなる軟弱地盤Ｇ１内に造成され拡径された砂杭ＳＣの径を計測する場合、まず、アクチュエータ駆動部５３から送られた駆動信号により水圧ユニット５９が作動してアクチュエータ１５Ａが駆動し、作動棒１５ａが下方に押し出されると、貫入ロッド１１が図１（ａ）の退避状態から下方に突出し、コーン部１２を先端にして砂杭ＳＣの上端面ＳＳから砂杭内部に貫入する（図４のＳ０１）。これにより弾性波送受信部１３，１４を有する貫入ロッド１１は、砂杭ＳＣの内部であって軸中心に位置する。   As shown in FIGS. 3A and 3B, when measuring the diameter of the sand pile SC that has been formed and expanded in the soft ground G1 made of viscous soil or the like by the casing pipe 10, first, the actuator drive unit 53 sends it. When the hydraulic pressure unit 59 is actuated by the received drive signal to drive the actuator 15A and the actuating rod 15a is pushed downward, the penetrating rod 11 projects downward from the retracted state of FIG. Then, it penetrates into the sand pile from the upper end surface SS of the sand pile SC (S01 in FIG. 4). Thereby, the penetration rod 11 which has the elastic wave transmission / reception parts 13 and 14 is located in the inside of the sand pile SC, and an axial center.

次に、弾性波送受信部１３，１４は、図２の送信部５５からの駆動信号により弾性波Ｔ１，Ｔ２を互いに反対の半径方向に送信すると、弾性波Ｔ１，Ｔ２が砂杭ＳＣと軟弱地盤Ｇ１との境界ＢＮの速度変化部で反射した反射波Ｒ１，Ｒ２を弾性波送受信部１３，１４が受信し、その受信信号が受信部５６に送信される。距離計測部５７は、砂杭ＳＣの弾性波速度と、弾性波Ｔ１，Ｔ２の送信時と反射波Ｒ１，Ｒ２の受信時との時間差とから距離を算出することで、拡径された砂杭ＳＣの直径を計測する（図４のＳ０２）。   Next, when the elastic wave transmission / reception units 13 and 14 transmit the elastic waves T1 and T2 in the opposite radial directions by the drive signal from the transmission unit 55 of FIG. 2, the elastic waves T1 and T2 are transmitted to the sand pile SC and the soft ground. The elastic waves transmitting and receiving units 13 and 14 receive the reflected waves R1 and R2 reflected by the velocity changing unit at the boundary BN with G1, and the received signal is transmitted to the receiving unit 56. The distance measurement unit 57 calculates the distance from the elastic wave velocity of the sand pile SC and the time difference between when the elastic waves T1 and T2 are transmitted and when the reflected waves R1 and R2 are received, thereby increasing the diameter of the sand pile. The diameter of the SC is measured (S02 in FIG. 4).

また、貫入ロッド１１を砂杭ＳＣの内部へ貫入させる時に、コーン部１２をアクチュエータ１５Ａにより一定速度で砂杭中に貫入させ、その貫入抵抗を計測装置２０の荷重計１９からの測定信号により荷重計測部５４で計測する（図４のＳ０３）。   When penetrating the rod 11 into the sand pile SC, the cone portion 12 is penetrated into the sand pile by the actuator 15A at a constant speed, and the penetration resistance is loaded by the measurement signal from the load meter 19 of the measuring device 20. The measurement is performed by the measurement unit 54 (S03 in FIG. 4).

上述のように計測された貫入抵抗に基づいて砂杭の圧縮強度を求める（図４のＳ０４）。すなわち、貫入抵抗qc（kN/m2）から一軸圧縮強度qu（kN/m2）を公知の式により求める。かかる式は、種々知られているが、一例を以下に示す。
qu＝ａ×ｑｃ＋b （１）
ここで、a＝０．００２３×Ｆｃ−0.0309 (Fc : 細粒分含有率)
b＝−０．４７３２×Ｆｃ＋47.519
なお、式（１）による演算は、たとえば、図２の制御部５８で行うように構成できる。 The compressive strength of the sand pile is determined based on the penetration resistance measured as described above (S04 in FIG. 4). That is, the uniaxial compressive strength qu (kN / m 2 ) is obtained from a penetration resistance qc (kN / m 2 ) by a known formula. Various such equations are known, but an example is shown below.
qu = a × qc + b (1)
Here, a = 0.0003 × Fc−0.0309 (Fc: fine grain content)
b = −0.4732 × Fc + 47.519
Note that the calculation according to the equation (1) can be configured to be performed by, for example, the control unit 58 of FIG.

上述のようにして計測された砂杭の径の計測値と設計値（目標値）とを比較することで砂杭形状（出来形）を評価する（図４のＳ０５）。また、砂杭強度の計測値と設計値（目標値）とを比較することで砂杭強度を評価する（図４のＳ０６）。これらの砂杭形状・砂杭強度の評価結果に基づいて砂杭造成の施工管理を行う（図４のＳ０７）。   The sand pile shape (finished shape) is evaluated by comparing the measured value of the diameter of the sand pile measured as described above with the design value (target value) (S05 in FIG. 4). Further, the sand pile strength is evaluated by comparing the measured value of the sand pile strength with the design value (target value) (S06 in FIG. 4). Based on the evaluation results of these sand pile shapes and sand pile strength, construction management of sand pile creation is performed (S07 in FIG. 4).

上述の弾性波の送受信による砂杭の径の計測方法によれば、砂杭ＳＣが管理された砂からなり、弾性波の速度のばらつきは少ないと考えられるため、比較的正確に砂杭ＳＣの径を計測できる。さらに、弾性波の反射面となる砂杭ＳＣと軟弱地盤Ｇ１との境界ＢＮは円形で、弾性波Ｔ１，Ｔ２は軸中心から出て広がるので、必ずしも志向性の高くない弾性波でも、反射波Ｒ１，Ｒ２が再び軸中心に集まり、反射波が強くなる。このため、弾性波の送受信による砂杭の径の計測時のＳＮ比が高くなり、計測性能が向上する。   According to the method for measuring the diameter of sand piles by transmitting and receiving elastic waves as described above, the sand pile SC is made of controlled sand, and it is considered that there is little variation in the velocity of the elastic waves. The diameter can be measured. Furthermore, since the boundary BN between the sand pile SC and the soft ground G1 serving as the elastic wave reflecting surface is circular and the elastic waves T1 and T2 spread out from the axial center, even if the elastic wave is not necessarily oriented, the reflected wave R1 and R2 gather again at the axial center, and the reflected wave becomes stronger. For this reason, SN ratio at the time of the measurement of the diameter of the sand pile by transmission / reception of an elastic wave becomes high, and measurement performance improves.

なお、図５のように、図１の弾性波送受信部１３，１４が弾性波を送信し、その反射波を連続的に受信しながら、弾性波の発信周波数を変化させると、弾性波の波長が砂杭の半径の２倍、４倍、あるいは整数分の一になる定在波周波数で、共鳴現象が起こり、受信波強度がピークを示すが、このときの波長によって砂杭の径を計測するようにしてもよい。   As shown in FIG. 5, when the elastic wave transmission / reception units 13 and 14 in FIG. 1 transmit elastic waves and continuously receive the reflected waves, and change the oscillation frequency of the elastic waves, the wavelength of the elastic waves Resonance phenomenon occurs at a standing wave frequency that is 2 times, 4 times, or an integral fraction of the sand pile radius, and the received wave intensity shows a peak. The diameter of the sand pile is measured at this wavelength. You may make it do.

また、上述の砂杭強度の計測方法によれば、式（１）等の式では、係数a,b等が細粒分含有率などにより変化するが、砂杭は比較的均質な細粒分の少ない砂を用いており、得られる一軸圧縮強度quのばらつきは少ないと考えられる。   Moreover, according to the sand pile strength measurement method described above, in the formula (1), etc., the coefficients a, b, etc. vary depending on the fine grain content, etc., but the sand pile has a relatively homogeneous fine grain fraction. It is considered that there is little variation in the uniaxial compressive strength qu obtained.

なお、砂杭強度として、貫入抵抗qc、一軸圧縮強度quからＮ値を求める式も種々知られている。粒径に依存するが、砂杭は比較的均質な細粒分の少ない砂を用いており、同様にばらつきは少ないと考えられる。   As sand pile strength, various formulas for obtaining an N value from penetration resistance qc and uniaxial compressive strength qu are also known. Although it depends on the particle size, sand piles use sand that is relatively homogeneous and contains a small amount of fine grains, and it is considered that there is little variation.

次に、本実施形態による砂杭の造成時における砂杭形状・強度の評価に基づくSCP工法の施工管理方法について図６，図７を参照して説明する。図６は、本実施形態による砂杭の造成工程（ａ）〜（ｇ）を示す概略図である。図７は、図６の砂杭造成工程と砂杭形状・強度の評価工程とを含む施工管理工程Ｓ２１〜Ｓ２８を説明するためのフローチャートである。   Next, the construction management method of the SCP method based on the sand pile shape / strength evaluation at the time of sand pile creation according to this embodiment will be described with reference to FIGS. FIG. 6 is a schematic view showing sand pile creation steps (a) to (g) according to the present embodiment. FIG. 7 is a flowchart for explaining the construction management steps S21 to S28 including the sand pile formation step and the sand pile shape / strength evaluation step of FIG.

図６のように、本実施形態は、表層の軟弱粘性土層Ｇ１とその下層の支持層Ｇ２とを有する水底地盤ＧＧ内にSCP工法によりケーシングパイプ１０を用いて砂杭ＳＣを造成するものである。作業船ＳＰは、砂杭の貫入・造成のためのSCP施工機械１５を搭載し、SCP施工機械１５は、ケーシングパイプ１０やその付属部を駆動し、バイブロハンマ１６でケーシングパイプ１０を振動させながら表層Ｇ１から地中に貫入させ、その砂供給口１０ａから供給される砂を地盤中に圧入し、締め固められた砂杭を地盤内に略鉛直方向に造成する。造成される砂杭の直径は、たとえば、２ｍであるが、適宜変更可能である。本実施形態のSCP工法の施工管理方法は、SCP工法の施工途中・直後に砂杭形状・強度を評価する工程を組み入れたものである。   As shown in FIG. 6, in this embodiment, a sand pile SC is created using a casing pipe 10 in a water bottom ground GG having a soft soil layer G1 as a surface layer and a support layer G2 as a lower layer using a casing pipe 10. is there. The work ship SP is equipped with an SCP construction machine 15 for intrusion and creation of sand piles, and the SCP construction machine 15 drives the casing pipe 10 and its attached part, and vibrates the casing pipe 10 with the vibro hammer 16 while oscillating the casing pipe 10. G1 penetrates into the ground, sand supplied from the sand supply port 10a is pressed into the ground, and the compacted sand pile is formed in the ground in a substantially vertical direction. The diameter of the sand pile to be created is 2 m, for example, but can be changed as appropriate. The construction management method for the SCP method of this embodiment incorporates a process for evaluating the shape and strength of sand piles during and immediately after the construction of the SCP method.

まず、図６（ａ）のように、作業船ＳＰを用いてSCP施工機械１５によりケーシングパイプ１０を砂杭の造成位置に設定する（Ｓ２１）。   First, as shown in FIG. 6A, the casing pipe 10 is set to the sand pile formation position by the SCP construction machine 15 using the work ship SP (S21).

次に、図６（ｂ）のように、SCP施工機械１５によりケーシングパイプ１０を表層の軟弱粘性土層Ｇ１に打ち込み貫入させる（Ｓ２２）。   Next, as shown in FIG. 6 (b), the casing construction pipe 10 is driven into the surface soft viscous soil layer G1 by the SCP construction machine 15 (S22).

次に、図６（ｃ）のように、ケーシングパイプ１０の先端が支持層Ｇ２に達したら、砂供給口１０ａから砂ＳＤを投入しケーシングパイプ１０内に供給する（Ｓ２３）。   Next, as shown in FIG. 6C, when the tip of the casing pipe 10 reaches the support layer G2, sand SD is introduced from the sand supply port 10a and supplied into the casing pipe 10 (S23).

次に、図６（ｄ）のように、SCP施工機械１５によりケーシングパイプ１０を引き抜く（Ｓ２４）。   Next, as shown in FIG. 6D, the casing pipe 10 is pulled out by the SCP construction machine 15 (S24).

次に、図６（ｅ）のように、SCP施工機械１５によりケーシングパイプ１０を打ち戻しバイブロハンマ１６で上下に振動を与えながら砂ＳＤを締め固めることで、下側に締め固められた大径の砂杭の一部ＳＣ１をつくる（Ｓ２５）。必要に応じて、砂投入工程Ｓ２３，ケーシングパイプ１０の引き抜き工程Ｓ２４、打ち戻し（締め固め）工程Ｓ２５を繰り返す。   Next, as shown in FIG. 6E, the casing pipe 10 is driven back by the SCP construction machine 15 and the sand SD is compacted while being vibrated up and down by the vibro hammer 16, so that the large diameter compacted downward. A part SC1 of the sand pile is made (S25). If necessary, the sand charging step S23, the casing pipe 10 drawing step S24, and the back-up (compacting) step S25 are repeated.

次に、工程Ｓ２５の打ち戻しによる締め固めを中断し、図３のようにケーシングパイプ１０の計測装置２０の貫入ロッド１１を大径の砂杭の一部ＳＣ１の上端面ＳＳから貫入させ、荷重計１９および弾性波送受信部１３，１４により図２の計測システム５０を用いて砂杭の一部ＳＣ１の径および強度を計測し（Ｓ２６）、図４のようにして砂杭形状・強度を評価し、その評価の結果、砂杭形状または砂杭強度が目標値を満足していない場合（Ｓ２７）、打ち戻し（締め固め）工程Ｓ２５に戻り、砂杭形状・強度が目標値を満足するまで、工程Ｓ２５〜Ｓ２７を繰り返す。   Next, the compaction by the reversal in step S25 is interrupted, and the penetration rod 11 of the measuring device 20 of the casing pipe 10 is penetrated from the upper end surface SS of a part SC1 of the large-diameter sand pile as shown in FIG. The diameter 19 and the strength of a part SC1 of the sand pile are measured using the measuring system 50 of FIG. 2 by the meter 19 and the elastic wave transmitting / receiving units 13 and 14 (S26), and the sand pile shape and strength are evaluated as shown in FIG. As a result of the evaluation, when the sand pile shape or the sand pile strength does not satisfy the target value (S27), the process returns to the strike back (consolidation) step S25 until the sand pile shape / strength satisfies the target value. Steps S25 to S27 are repeated.

次に、砂杭造成を次の深度まで行う場合（Ｓ２８）、工程Ｓ２３に戻り、同様の工程を経て、図６（ｆ）のように大径の砂杭の一部ＳＣ２（図６（ｅ）の砂杭の一部ＳＣ１よりも高さが高い）をつくり、砂杭の径の計測工程（Ｓ２６）を経て砂杭形状・強度が目標値を満足することを確認する。   Next, when sand pile creation is performed to the next depth (S28), the process returns to step S23, and through a similar process, a part SC2 of the large-diameter sand pile (FIG. 6 (e)). ) And a sand pile diameter measuring step (S26) to confirm that the sand pile shape / strength satisfies the target value.

以上の工程を経て砂杭ＳＣを、図５（ｇ）のように、表層の軟弱粘性土層Ｇ１内に造成する。本実施形態では、図５（ｅ）〜（ｇ）の砂杭の一部（ＳＣ１，ＳＣ２）を造成した段階および砂杭ＳＣが完成した段階で砂杭の径・強度の計測による砂杭形状・強度の評価を実行し目標値を満足することを確認するので、地盤に造成される砂杭の形状・強度品質に関する施工管理を確実に行うことができ、高品質な砂杭を造成できる。また、砂杭形状・強度の評価結果に基づいて砂杭造成の諸施工条件（たとえば、砂投入量や砂杭造成長）を施工途中で見直して適宜変更できるので、適切な施工管理が可能となる。   The sand pile SC is formed in the soft clay soil layer G1 of the surface layer as shown in FIG. In the present embodiment, the shape of the sand pile by measuring the diameter and strength of the sand pile at the stage where the sand piles (SC1, SC2) shown in FIGS.・ Because the strength evaluation is performed and it is confirmed that the target value is satisfied, construction management related to the shape and strength quality of the sand pile created on the ground can be reliably performed, and a high-quality sand pile can be created. In addition, various construction conditions for sand pile creation (for example, sand input and sand pile growth) can be reviewed and changed appropriately during construction based on the sand pile shape and strength evaluation results, enabling appropriate construction management. Become.

以上のように、本実施形態によるSCP工法の施工管理方法によれば、次の効果を奏する。
(1)従来までは砂杭造成時における砂杭形状・強度の評価ができなかったのに対し、砂杭造成時に砂杭形状・強度の評価・確認が可能である。
(2)砂杭造成時に砂杭形状・強度評価を行っているので全数調査が可能である。
(3)砂杭をたとえば約１ｍ造成する度に砂杭形状・強度の評価・確認を行うことができるので、目標値（設計値）を満たしていない箇所を早期に発見することができ、締固め等を行うことで即座に補修を行うことができ、高品質の砂杭を造成することが可能になる。従来まで困難であった砂杭造成後の手直しは不要となる。 As described above, according to the construction management method of the SCP method according to the present embodiment, the following effects can be obtained.
(1) Previously, sand pile shape and strength could not be evaluated at the time of sand pile construction, but sand pile shape and strength could be evaluated and confirmed at sand pile construction.
(2) Since the sand pile shape and strength are evaluated at the time of sand pile construction, a complete survey is possible.
(3) Sand pile shape / strength can be evaluated and confirmed each time a sand pile is built, for example, about 1 m, so that a point that does not meet the target value (design value) can be found at an early stage. Repairing can be performed immediately by hardening, and high-quality sand piles can be created. Rework after sand pile construction, which was difficult until now, is no longer necessary.

なお、計測装置２０の貫入ロッド１１の貫入時において、砂杭直径がたとえば、２００ｃｍ、高さ（各ステップごと）１ｍに対し、貫入ロッド１１の貫入量は弾性波送受信部が砂杭内で正常に働く程度でよく（例えば１０ｃｍ）、貫入ロッド１１の直径も数ｃｍなので、造成された砂杭での損傷は少ない。   When the penetrating rod 11 of the measuring device 20 penetrates, the sand pile diameter is 200 cm and the height (each step) is 1 m, and the penetrating amount of the penetrating rod 11 is normal in the sand pile. Since the diameter of the penetrating rod 11 is several centimeters, there is little damage on the sand pile that has been created.

以上のように本発明を実施するための形態について説明したが、本発明はこれらに限定されるものではなく、本発明の技術的思想の範囲内で各種の変形が可能である。たとえば、図６（ｅ）〜（ｇ）、図７では、砂杭の一部ＳＣ１，ＳＣ２および砂杭ＳＣについて砂杭の径の計測・評価を実行し目標値を満足することを確認するが、さらに多段階に多くの深度で、所定の高さ（たとえば１ｍ）毎に行ってもよい。   As described above, the modes for carrying out the present invention have been described. However, the present invention is not limited to these, and various modifications can be made within the scope of the technical idea of the present invention. For example, in FIGS. 6 (e) to 6 (g) and FIG. 7, it is confirmed that the sand pile diameter is measured and evaluated for a part of the sand piles SC1, SC2 and the sand pile SC to satisfy the target value. Further, it may be performed for each predetermined height (for example, 1 m) at many depths in many stages.

また、図１の弾性波送受信部１３，１４は、１つの圧電素子で弾性波の送信と受信を兼用したが、送信用と受信用とに分けそれぞれに圧電素子を設けてもよい。また、弾性波の発信方式は、パルス波の発信や連続波の発信であってよい。   In addition, although the acoustic wave transmission / reception units 13 and 14 of FIG. 1 share both transmission and reception of elastic waves with one piezoelectric element, piezoelectric elements may be provided separately for transmission and reception. The elastic wave transmission method may be pulse wave transmission or continuous wave transmission.

また、アクチュエータ１５Ａは、水圧シリンダに限定されず、油圧や空気圧で作動するシリンダや電磁式のものから構成してもよい。   In addition, the actuator 15A is not limited to a hydraulic cylinder, and may be a cylinder that operates by hydraulic pressure or pneumatic pressure, or an electromagnetic type.

また、貫入抵抗は、貫入ロッド１１に内蔵させたロードセルで計測してもよく、また、アクチュエータ１５Ａを水圧シリンダや油圧シリンダ等から構成した場合、シリンダに備える圧力計から出力する貫入圧力（電気信号）から計測するようにしてもよい。   Further, the penetration resistance may be measured by a load cell built in the penetration rod 11, and when the actuator 15A is constituted by a hydraulic cylinder, a hydraulic cylinder or the like, the penetration pressure (electrical signal) output from a pressure gauge provided in the cylinder. ) May be measured.

また、図６は、砂杭を水底に造成する例を示すが、本発明はこれに限定されず、陸上の地盤に砂杭を造成する場合にも適用できることはもちろんである。   FIG. 6 shows an example in which a sand pile is created on the bottom of the water, but the present invention is not limited to this, and it is needless to say that the present invention can also be applied to the case of creating a sand pile on land.

また、ケーシングパイプ１０の稼働中に図１（ａ）の収容部１６Ａ内に砂が侵入するのを防ぐために、貫入ロッド１１の摺動部分にシール部１７ｂを設けているが、さらに収容部１６Ａ内に水を常時注入して、貫入ロッド１１とシール部１７ｂとの間に常に外側（図１（ａ）の下側）に向かう水の流れを形成して砂の侵入を防ぐようにしてもよい。   Further, in order to prevent sand from entering the housing portion 16A of FIG. 1A during the operation of the casing pipe 10, a seal portion 17b is provided at the sliding portion of the penetrating rod 11, but the housing portion 16A is further provided. Water is always injected into the inside, and a water flow is always formed between the penetrating rod 11 and the seal portion 17b toward the outside (the lower side of FIG. 1A) to prevent sand from entering. Good.

本発明によれば、SCP工法による地盤での砂杭造成途中および直後に砂杭の径を計測し砂杭形状・強度を確認し評価できるので、高品質の砂杭造成が可能となる。   According to the present invention, it is possible to measure and evaluate the sand pile shape / strength during and immediately after sand pile formation on the ground by the SCP method, so that high quality sand pile formation is possible.

１０ SCP工法用ケーシングパイプ、ケーシングパイプ
１１ 貫入ロッド
１２ コーン部
１３，１４ 弾性波送受信部
１５Ａ アクチュエータ
１９ 荷重計
２０ 計測装置
５０ 計測システム
ＢＮ 砂杭と軟弱地盤との境界（速度変化部）
Ｇ１ 軟弱地盤、表層、軟弱粘性土層
ＧＧ 水底地盤
Ｌ 配線
Ｔ１，Ｔ２ 弾性波
Ｒ１，Ｒ２ 反射波
ＳＣ 砂杭
ＳＳ 上端面 10 SCP pipe casing pipe, casing pipe 11 Penetration rod 12 Cone parts 13, 14 Elastic wave transmission / reception part 15A Actuator 19 Load meter 20 Measuring device 50 Measurement system BN Boundary between sand pile and soft ground (speed changing part)
G1 Soft ground, surface layer, soft viscous soil layer GG Water bottom ground L Wiring T1, T2 Elastic wave R1, R2 Reflected wave SC Sand pile SS Upper end surface

Claims (7)

サンドコンパクションパイル工法用ケーシングパイプの下部内周の中心に配置され軸方向に伸縮可能な貫入ロッドと、
前記貫入ロッドを突出させまた退避させるためのアクチュエータと、
前記貫入ロッドの先端近傍に設けられた弾性波送受信部と、を備え、
前記貫入ロッドを、前記ケーシングパイプで地盤に造成された砂杭の上端面から前記アクチュエータにより突出させて砂杭内部に貫入させ、前記弾性波送受信部が弾性波を前記砂杭の半径方向に送信し、その反射波を受信することで、前記砂杭の径を計測するサンドコンパクションパイル工法用計測装置。 A penetrating rod that is arranged at the center of the inner periphery of the lower part of the casing pipe for sand compaction pile method, and that can extend and contract in the axial direction
An actuator for projecting and retracting the penetrating rod;
An elastic wave transmitting / receiving unit provided near the tip of the penetrating rod,
The penetration rod protrudes from the upper end surface of the sand pile formed on the ground by the casing pipe by the actuator and penetrates into the sand pile, and the elastic wave transmitting / receiving unit transmits elastic waves in the radial direction of the sand pile. And the measuring apparatus for sand compaction pile methods which measures the diameter of the said sand pile by receiving the reflected wave. 前記弾性波送受信部から弾性波を所定の半径方向およびその半径方向と180度異なる半径方向にそれぞれ送信し、各反射波を受信し、前記砂杭の径を計測する請求項１に記載のサンドコンパクションパイル工法用計測装置。   The sand according to claim 1, wherein an elastic wave is transmitted from the elastic wave transmitting / receiving unit in a predetermined radial direction and a radial direction 180 degrees different from the radial direction, each reflected wave is received, and the diameter of the sand pile is measured. Measuring device for compaction pile method. 前記弾性波の発信周波数を変化させながら前記送信および前記受信を行い、
前記受信時に測定された最大受信波強度に対応した発信周波数に基づいて前記砂杭の径を計測する請求項１または２に記載のサンドコンパクションパイル工法用計測装置。 Performing the transmission and the reception while changing the oscillation frequency of the elastic wave,
The sand compaction pile measuring device according to claim 1 or 2, wherein a diameter of the sand pile is measured based on a transmission frequency corresponding to a maximum received wave intensity measured at the time of reception. 前記貫入ロッドの砂杭内部への貫入時の貫入抵抗を測定する荷重計をさらに備え、
前記貫入時に測定された貫入抵抗に基づいて前記砂杭の強度を計測する請求項１乃至３のいずれかに記載のサンドコンパクションパイル工法用計測装置。 A load meter for measuring penetration resistance at the time of penetration into the sand pile of the penetration rod;
The measuring device for sand compaction pile method according to any one of claims 1 to 3, wherein the strength of the sand pile is measured based on penetration resistance measured at the time of penetration. 地盤に砂杭を造成するサンドコンパクションパイル工法に用いられるケーシングパイプであって、請求項１乃至４のいずれかに記載のサンドコンパクションパイル工法用計測装置を備えるサンドコンパクションパイル工法用ケーシングパイプ。   A casing pipe for a sand compaction pile method, comprising a measuring device for a sand compaction pile method according to any one of claims 1 to 4, wherein the casing pipe is used for a sand compaction pile method for creating a sand pile on the ground. 請求項１乃至４のいずれかに記載の計測装置を用いて、サンドコンパクションパイル工法により地盤に砂杭を造成する施工を管理する方法であって、
前記砂杭の造成途中または造成後に前記上端面から前記貫入ロッドを砂杭内部に貫入させ、
前記弾性波送受信部での前記弾性波の送信および前記反射波の受信により前記砂杭の径を計測し、
前記計測値に基づいて前記砂杭の形状を評価し、
前記評価結果に基づいてサンドコンパクションパイル工法の施工を管理する施工管理方法。 Using the measuring device according to any one of claims 1 to 4, a method for managing construction for creating a sand pile on the ground by a sand compaction pile method,
During the sand pile construction or after construction, the penetration rod penetrates the sand pile from the upper end surface,
Measure the diameter of the sand pile by transmitting the elastic wave and receiving the reflected wave at the elastic wave transmitting and receiving unit,
Evaluate the shape of the sand pile based on the measured value,
A construction management method for managing the construction of the sand compaction pile method based on the evaluation result. 請求項４に記載の計測装置を用いて、サンドコンパクションパイル工法により地盤に砂杭を造成する施工を管理する方法であって、
前記砂杭の造成途中または造成後に前記上端面から前記貫入ロッドを砂杭内部に貫入させ、
前記貫入時に前記荷重計により貫入抵抗を測定し、
前記測定された貫入抵抗に基づいて前記砂杭の強度を求めて評価し、
前記評価結果に基づいてサンドコンパクションパイル工法の施工を管理する施工管理方法。 Using the measuring device according to claim 4, a method for managing construction for creating a sand pile on the ground by a sand compaction pile method,
During the sand pile construction or after construction, the penetration rod penetrates the sand pile from the upper end surface,
Measure penetration resistance with the load meter at the time of penetration,
Evaluate the strength of the sand pile based on the measured penetration resistance,
A construction management method for managing the construction of the sand compaction pile method based on the evaluation result.
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