JP2011231568A - Pore water pressure measuring device, soft ground improvement method using the same, method for determining dynamic state of ground for underground installation, and method for determining dynamic state of ground for banking structure installation - Google Patents

Pore water pressure measuring device, soft ground improvement method using the same, method for determining dynamic state of ground for underground installation, and method for determining dynamic state of ground for banking structure installation Download PDF

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JP2011231568A
JP2011231568A JP2010104813A JP2010104813A JP2011231568A JP 2011231568 A JP2011231568 A JP 2011231568A JP 2010104813 A JP2010104813 A JP 2010104813A JP 2010104813 A JP2010104813 A JP 2010104813A JP 2011231568 A JP2011231568 A JP 2011231568A
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Kazuyoshi Nakakuma
和義 中熊
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Maruyama Kogyo Co Ltd
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Abstract

PROBLEM TO BE SOLVED: To provide a pore water pressure measuring device for repeatable use, soft ground improvement method using the same, a method for determining a dynamic state of a ground for underground installation, and a method for determining a dynamic state of a ground for banking structure installation.SOLUTION: A pore water pressure measuring device comprises a pipe member 21 with the upper end side 21a extending above the ground, a filter part 22 arranged at the open lower end side 21b of the pipe member 21, and a pressure sensor 24 fixed to the upper end side. An air reservoir 23 is formed above the water level of the pore water of the ground flowing into the pipe through the filter part at the upper part side 21a of the pipe member. A pressure receiving part 24a of the pressure sensor 24 is exposed in the air reservoir 23 formed at the upper end side 21a of the pipe member, so as to measure fluctuations of the air pressure in the air reservoir 23 due to rises and falls of the pore water level flowing into the pipe member resulting from fluctuations of the pore water pressure in the ground.

Description

本発明は、間隙水圧測定装置、それを用いた軟弱地盤の改良工法、地下埋設物が埋設される地盤の動態把握方法、及び盛土構造物が造成される地盤の動態把握方法に関する。詳細には、簡単に施工することができ、しかも高価な圧力センサーは、埋め殺しをせずに何度も再利用することができる間隙水圧測定装置、それを用いた軟弱地盤の改良工法、地下埋設物が埋設される地盤の動態把握方法、及び盛土構造物が造成される地盤の動態把握方法に関する。   The present invention relates to a pore water pressure measuring device, a soft ground improvement method using the pore water pressure measuring device, a ground dynamic grasping method in which an underground buried object is buried, and a ground dynamic grasping method in which an embankment structure is created. In detail, the pressure sensor that can be installed easily and is expensive, the pore water pressure measuring device that can be reused many times without being buried, the improvement method of soft ground using it, the underground The present invention relates to a method for grasping the dynamics of the ground where the buried object is buried and a method for grasping the dynamics of the ground where the embankment structure is created.

従来、例えば軟弱地盤上に家屋、上下水道、擁壁あるいは舗装道路などの構造物を設置する場合、これら構造物を地盤の沈下が完全に終了する前に設置すると、該軟弱地盤はその支持力がきわめて弱いことから、これら構造物の荷重を支えきれずに不等沈下を生じ、この結果、軟弱地盤上の構造物が損壊してしまうことになる。これは単なる構造物の損壊に止まらず、人命をも巻き込んだ大災害に発展する恐れもある。   Conventionally, when a structure such as a house, water and sewerage, a retaining wall, or a paved road is installed on soft ground, for example, if the structure is installed before the settlement of the ground is completely completed, the soft ground has its bearing capacity. Is extremely weak, so that the load of these structures cannot be supported and uneven settlement occurs, resulting in damage to the structure on the soft ground. This does not stop at just damaging the structure, but may develop into a catastrophe involving human life.

このため、軟弱地盤上への構造物の設置は、地盤の沈下が完全に終了するのを待って行われていた。この際、軟弱地盤の沈下終了は、沈下計の挙動を測定して判断していた。また確実を期すため、ボーリングによって資料を採取し、強度試験などの分析を行って、この分析結果も合わせて終了判断を行うこともあった。   For this reason, the installation of the structure on the soft ground has been performed after the settlement of the ground is completely completed. At this time, the settlement of the soft ground was judged by measuring the behavior of the settlement meter. In addition, for the sake of certainty, materials were collected by boring, and analysis such as strength tests was performed, and this analysis result was also used to determine termination.

ところが、沈下計の挙動を測定することのみで、軟弱地盤の沈下終了を判断する場合、その測定には人為的な誤差が含まれてしまい正確な測定を行うことは難しく、適正な沈下終了の判断を行うことができず、しかも軟弱地盤といっても種類は様々であり、その深度も地層も異なっていることから、例えば沈下量が小さくなったなどの沈下計の挙動だけから、終了判断するのは余りに無謀であり、危険でもあった。   However, when measuring the settlement of soft ground only by measuring the behavior of the settlement meter, it is difficult to make an accurate measurement because the measurement includes human error. Judgment is not possible, and even if it is called soft ground, there are various types, and the depth and the strata are different, so it is judged only based on the behavior of the subsidometer, for example, the amount of subsidence has decreased. It was too reckless and dangerous to do.

ボーリングによる資料の採取、分析は、軟弱地盤の沈下終了を判断する上で大変に有効な手段ではある。しかしながら、ボーリングによる資料の採取、分析には、多額の費用を要するので、ボーリング調査できる箇所も限られていた。   The collection and analysis of materials by boring is a very effective means for judging the end of subsidence in soft ground. However, collecting and analyzing materials by boring requires a large amount of money, so there are only a few places where boring surveys can be conducted.

このような事情から、軟弱地盤上に構造物を設置する場合には、安全を期して予め支持杭などを地盤中に打設し、その上に構造物や盛土を設置するという方法が採られていた。   For this reason, when installing a structure on soft ground, a method of placing a support pile or the like in the ground in advance for safety and installing a structure or embankment on it is adopted. It was.

このような技術的課題を鑑み、本発明者は、軟弱地盤の動態を高い精度で把握することで、正確な軟弱地盤の沈下終了の判断を下せるようにした軟弱地盤の動態把握システムを提供している（例えば特許文献１参照）。   In view of such technical problems, the present inventor provides a soft ground dynamics grasping system that can accurately determine the end of subsidence of soft ground by grasping the dynamics of soft ground with high accuracy. (For example, refer to Patent Document 1).

そのシステムは、軟弱地盤に対する上積荷重を把握する手段と、上積荷重による地盤の沈下量を把握する手段と、地盤の沈下に伴う圧密水の排水量を把握する手段と、地盤より排水された水の温度を把握する手段とからなることを特徴とするものである。   The system has a means for grasping the load on the soft ground, a means for grasping the amount of ground subsidence due to the load on the ground, a means for grasping the drainage amount of the compacted water accompanying the ground subsidence, and the drainage from the ground. It is characterized by comprising means for grasping the temperature of water.

このシステムにおいて、発明者は、軟弱地盤に対する上積荷重の把握手段として、図６に示すように、軟弱地盤Ａの表層を覆う気密シート１４と、軟弱地盤Ａ中に予め設置しておいた真空ポンプ１３に接続する通水管１１と、軟弱地盤Ａ中に所定の間隔をおいて打設され、前記通水管１１に上端が接続するドレーン材１２と、軟弱地盤Ａ中に設置された圧力センサーＲとからなるものを提案しており、これにより、気密シート１４で覆われ、真空ポンプ１３に接続する通水管１１及びドレーン材１２を介して負圧状態におかれた軟弱地盤Ａ中及びまたは軟弱地盤表層の真空度を前記圧力センサーＲによって測定するようにしていた。   In this system, the inventor, as means for grasping the upper load on the soft ground, as shown in FIG. 6, the airtight sheet 14 covering the surface layer of the soft ground A, and the vacuum previously set in the soft ground A A water pipe 11 connected to the pump 13, a drain material 12 placed at a predetermined interval in the soft ground A, and an upper end connected to the water pipe 11, and a pressure sensor R installed in the soft ground A In this way, the soft ground A covered with the airtight sheet 14 and placed in the negative pressure state through the water pipe 11 and the drain material 12 connected to the vacuum pump 13 and / or the soft ground The degree of vacuum of the ground surface layer was measured by the pressure sensor R.

特開平０９−１２５３５５号公報JP 09-125355 A

ところが、上記システムにおいて、軟弱地盤に対する上積荷重の把握手段として使用する圧力センサーは大変に高価であり、正確を期すためには改良する地盤内であって地盤深くにいくつも設置する必要があり、しかもその圧力センサーは施工後、埋め殺しとされるため、軟弱地盤内に圧力センサーを設置して上積荷重の把握手段とするには、大変に多くの手間と費用とを要していた。また、従来のシステムでは、施工後、圧力センサーを地盤内に埋め殺しとしていたため、圧力センサーのキャリブレーションは埋設前に行うだけであり、しかも該センサーが故障した場合、対処不能であった。   However, in the above system, the pressure sensor used as a means of grasping the overlay load on the soft ground is very expensive, and it is necessary to install a number of deep sensors in the ground to be improved for accuracy. Moreover, since the pressure sensor is buried after construction, it takes a lot of labor and cost to install the pressure sensor in the soft ground and to grasp the upper load. . Moreover, in the conventional system, since the pressure sensor was buried in the ground after construction, the calibration of the pressure sensor was only performed before the embedding, and it was impossible to cope with the failure of the sensor.

本発明は、このような事情に鑑みなされたものであり、簡単に施工することができ、しかも高価な圧力センサーは、埋め殺しをせずに何度も再利用することができる新規な間隙水圧測定装置、それを用いた軟弱地盤の改良工法、地下埋設物が埋設される地盤の動態把握方法、及び盛土構造物が造成される地盤の動態把握方法を提供することを目的とするものである。   The present invention has been made in view of such circumstances, and a novel pore water pressure which can be easily constructed and an expensive pressure sensor can be reused many times without being buried. It is intended to provide a measuring device, an improvement method for soft ground using the same, a method for grasping the dynamics of the ground in which underground structures are buried, and a method for grasping the dynamics of the ground in which embankment structures are created. .

上記目的を達成するため、請求項１記載の発明は、地盤内の間隙水圧を測定する装置であって、
地盤内の所定深さ位置に配置される共に上端側が地上まで延びて配置される管体と、 前記管体の開放された下端側に設けたフィルタ部と、
前記管体の閉鎖された上端側に取り付けられる圧力センサーと、
を備えており、前記管体の上端側には前記フィルタ部を通して管内に入り込んだ地盤内の間隙水の水面との間に空気溜が形成されるようになっており、
前記管体の上端側に形成される空気溜内には圧力センサーの受圧部が露出するように配置されており、この圧力センサーの受圧部によって前記地盤内の間隙水圧の変動によって変化する前記管内に入り込んだ間隙水の水位の上昇又は降下による前記空気溜内の空気圧の変化を測定するようにしたことを特徴とする間隙水圧測定装置をその要旨とした。 In order to achieve the above object, the invention according to claim 1 is an apparatus for measuring pore water pressure in the ground,
A tubular body that is disposed at a predetermined depth position in the ground and that has an upper end extending to the ground, and a filter portion provided on the opened lower end side of the tubular body;
A pressure sensor attached to the closed upper end of the tube;
And an air reservoir is formed between the upper surface of the tube body and the surface of pore water in the ground that has entered the tube through the filter portion.
A pressure receiving part of a pressure sensor is disposed so as to be exposed in an air reservoir formed on the upper end side of the pipe body, and the pressure receiving part of the pressure sensor changes the internal pressure of the pipe that changes due to fluctuations in pore water pressure in the ground. The gist of the pore water pressure measuring device is characterized in that a change in the air pressure in the air reservoir due to the rise or fall of the water level of the pore water that has entered is measured.

請求項２記載の発明は、地盤内の所定深さ位置に複数の管体が間隔を置いて配置され、前記複数の管体の上端側が１つの圧力センサーにまとめて取り付けられており、前記１つの圧力センサーによって前記複数の各管体の上端側に形成される空気溜内の空気圧が測定されるようにしたことを特徴とする請求項１に記載の間隙水圧測定装置をその要旨とした。   According to a second aspect of the present invention, a plurality of pipes are disposed at predetermined depth positions in the ground at intervals, and upper ends of the plurality of pipes are attached to a single pressure sensor. The gist of the pore water pressure measuring device according to claim 1, wherein the air pressure in the air reservoir formed on the upper end side of each of the plurality of tubes is measured by two pressure sensors.

請求項３記載の発明は、改良する軟弱地盤内に真空圧を利用して改良地盤周辺部と隔離された減圧領域を造り出し、前記軟弱地盤中の間隙水を排水することで、該軟弱地盤を硬質地盤へと改良する軟弱地盤の改良工法において、前記軟弱地盤に対する上積荷重を把握するために該地盤内に配置される間隙水圧測定手段として用いられることを特徴とする請求項１又は２のいずれかに記載の間隙水圧測定装置をその要旨とした。   The invention according to claim 3 creates a reduced pressure region isolated from the periphery of the improved ground using vacuum pressure in the soft ground to be improved, and drains pore water in the soft ground, thereby In the improvement method of the soft ground which improves to a hard ground, in order to grasp | ascertain the upper load to the said soft ground, it is used as a pore water pressure measuring means arrange | positioned in this ground. The gist of any one of the pore water pressure measuring devices is used.

請求項４記載の発明は、地下埋設物が地盤の変動に伴って損傷を受けるのを未然に察知するために、前記地盤内の地下埋設物近傍に配置され、前記地盤の変動に伴う間隙水圧の変動を測定するために用いられることを特徴とする請求項１又は２のいずれかに記載の間隙水圧測定装置をその要旨とした。   The invention according to claim 4 is arranged in the vicinity of the underground buried object in the ground in order to detect in advance that the underground buried object will be damaged due to the ground change, and the pore water pressure accompanying the ground fluctuation. The gist of the pore water pressure measuring device according to any one of claims 1 and 2, characterized in that the gage is used to measure the fluctuation of the water.

請求項５記載の発明は、盛土構造物が地盤の変動に伴って損傷を受けるのを未然に察知するために、前記地盤内に配置され、前記地盤の変動に伴う間隙水圧の変動を測定するために用いられることを特徴とする請求項１又は２のいずれかに記載の間隙水圧測定装置をその要旨とした。   The invention according to claim 5 is arranged in the ground to detect in advance that the embankment structure is damaged due to the ground change, and measures the variation of the pore water pressure accompanying the ground change. The gist of the pore water pressure measuring device according to any one of claims 1 and 2 is used.

請求項６記載の発明は、改良する軟弱地盤内に真空圧を利用して改良地盤周辺部と隔離された減圧領域を造り出し、前記軟弱地盤中の間隙水を排水することで、該軟弱地盤を硬質地盤へと改良する軟弱地盤の改良工法において、
前記軟弱地盤に対する上積荷重を把握するために請求項１又は２のいずれかに記載の間隙水圧測定装置を用いたことを特徴とする軟弱地盤の改良工法をその要旨とした。 The invention according to claim 6 creates a reduced pressure region isolated from the periphery of the improved ground using vacuum pressure in the soft ground to be improved, and drains pore water in the soft ground, thereby In the improvement method of soft ground to improve to hard ground,
The gist of the improvement method for soft ground, characterized in that the pore water pressure measuring device according to claim 1 or 2 is used to grasp the upper load on the soft ground.

請求項７記載の発明は、地下埋設物が地盤の変動に伴って損傷を受けるのを未然に察知するために、前記地盤内の地下埋設物近傍に配置され、前記地盤の変動に伴う間隙水圧の変動を測定するために請求項１又は２のいずれかに記載の間隙水圧測定装置を用いたことを特徴とする地下埋設物が埋設される地盤の動態把握方法をその要旨とした。   The invention according to claim 7 is arranged in the vicinity of the underground buried object in the ground in order to detect in advance that the underground buried object will be damaged due to the ground change, and the pore water pressure accompanying the ground fluctuation. The gist of the method for grasping the ground dynamics in which underground buried objects are embedded, characterized in that the pore water pressure measuring device according to claim 1 or 2 is used to measure the fluctuations of the ground.

請求項８記載の発明は、盛土構造物が地盤の変動に伴って損傷を受けるのを未然に察知するために、前記地盤内に配置され、前記地盤の変動に伴う間隙水圧の変動を測定するために請求項１又は２のいずれかに記載の間隙水圧測定装置を用いたことを特徴とする盛土構造物が造成される地盤の動態把握方法をその要旨とした。   The invention according to claim 8 is arranged in the ground in order to detect in advance that the embankment structure is damaged due to the ground change, and measures the variation in pore water pressure accompanying the ground change. Therefore, the gist of the method for grasping the dynamics of the ground on which the embankment structure is formed, characterized in that the pore water pressure measuring device according to claim 1 or 2 is used.

本発明の間隙水圧測定装置にあっては、管体を地盤内の所定深さ位置に配置する共に上端側が地上まで延びて配置したとき、前記管体の開放された下端側に設けたフィルタ部を通して地盤内の間隙水が該管体内に入り込み、前記管体の閉鎖された上端側に該管体内に入り込んだ地盤内の間隙水の水面との間に空気溜が形成されるようになっている。   In the pore water pressure measuring device of the present invention, when the pipe body is arranged at a predetermined depth position in the ground and the upper end side extends to the ground, the filter section provided on the opened lower end side of the pipe body Through the interstitial water in the ground through the pipe body, an air reservoir is formed between the closed upper end side of the pipe body and the surface of the pore water in the ground that has entered the pipe body. Yes.

そして、前記地盤内の間隙水圧の変動によって変化する前記管内に入り込んだ間隙水の水位の上昇又は降下による前記空気溜内の空気圧の変化を前記空気溜内に露出するように配置される圧力センサーの受圧部によって測定するようになっているのである。このため、従来の軟弱地盤の動態把握システムのように、軟弱地盤深くにいくつもの圧力センサーを設置する必要が無く、簡単に施工することができる。また、圧力センサーは、管体の閉鎖された上端側に配置されるため、埋め殺しをせずに何度も再利用することができる。このため、圧力センサーのキャリブレーションを常時行うことができ、より正確な間隙水圧の測定ができるようになっている。また、圧力センサーを埋め殺しにしないため、該センサーが故障した場合、いつでも簡単に対処が可能である。   And a pressure sensor disposed so as to expose a change in air pressure in the air reservoir due to an increase or decrease in the level of pore water that has entered the pipe, which changes due to a change in pore water pressure in the ground. It is to be measured by the pressure receiving part. For this reason, unlike the conventional soft ground dynamic grasping system, it is not necessary to install a number of pressure sensors deep in the soft ground and can be easily constructed. Moreover, since the pressure sensor is disposed on the closed upper end side of the tube body, it can be reused many times without being buried. For this reason, the calibration of the pressure sensor can always be performed, and the pore water pressure can be measured more accurately. Also, since the pressure sensor is not buried, it can be easily dealt with whenever the sensor fails.

本発明の間隙水圧測定装置は、上記作用効果を奏するものであり、軟弱地盤の改良工法における上積荷重の把握手段として、地下埋設物の地盤変動に伴う損傷の未然察知手段として、或いは盛土構造物の地盤変動に伴う損傷の未然察知手段として好適に用いることができる。   The pore water pressure measuring device of the present invention has the above-described effects, and is used as a means for grasping an upper load in an improved construction method for soft ground, as a means for detecting damage due to ground fluctuation of an underground buried object, or as an embankment structure. It can be suitably used as a means for detecting damage due to ground fluctuation of an object.

本発明の間隙水圧測定装置を軟弱地盤の改良工法における上積荷重の把握手段として適用した例であって、該間隙水圧測定装置を地盤内に配置した状態を示す模式図。The schematic diagram which shows the state which is the example which applied the pore water pressure measuring apparatus of this invention as a grasping means of the upper load in the improvement method of a soft ground, and has arrange | positioned this pore water pressure measuring apparatus in the ground. 図１に示す間隙水圧測定装置を示す拡大模式図。The expansion schematic diagram which shows the pore water pressure measuring apparatus shown in FIG. 本発明の間隙水圧測定装置を軟弱地盤の改良工法における上積荷重の把握手段として適用した別例を示す模式図。The schematic diagram which shows the other example which applied the pore water pressure measuring apparatus of this invention as a grasping means of the upper load in the improvement method of a soft ground. 地下埋設物が地盤の変動に伴って損傷するのを未然に察知する手段として本発明の間隙水圧測定装置を適用した例を示す模式図。The schematic diagram which shows the example which applied the pore water pressure measuring apparatus of this invention as a means to detect beforehand that an underground embedment is damaged with the fluctuation | variation of the ground. 盛土構造物が地盤の変動に伴って損傷するのを未然に察知する手段として本発明の間隙水圧測定装置を適用した例を示す模式図。The schematic diagram which shows the example which applied the pore water pressure measuring apparatus of this invention as a means to detect beforehand that an embankment structure is damaged with the fluctuation | variation of the ground. 従来の軟弱地盤の改良工法における上積荷重の把握手段として適用した例を示す模式図。The schematic diagram which shows the example applied as a grasping means of the upper load in the improvement method of the conventional soft ground.

以下、本発明の間隙水圧測定装置、それを用いた軟弱地盤の改良工法、地下埋設物が埋設される地盤の動態把握方法、及び盛土構造物が造成される地盤の動態把握方法をさらに詳しく説明する。本発明の間隙水圧測定装置（以下、単に装置という）は、硬質地盤へと改良される軟弱地盤、電話線や上水道などのパイプやケーブルといった地下埋設物が埋設される地盤、高速道路、堤防道路、鉄道、滑走路などの盛土構造物が造成される地盤、法面背後の地盤、或いはトンネル周囲の地盤内に配置されて、該地盤内の間隙水圧を測定する装置である。   Hereinafter, the pore water pressure measuring apparatus of the present invention, the soft ground improvement method using the same, the ground dynamics grasping method in which underground buried objects are embedded, and the ground dynamics grasping method in which the embankment structure is created will be described in more detail. To do. The pore water pressure measuring device (hereinafter simply referred to as “device”) of the present invention includes a soft ground improved to a hard ground, a ground in which underground objects such as pipes and cables such as telephone lines and waterworks are buried, a highway, and a dike road. It is a device for measuring pore water pressure in the ground, which is arranged on the ground where a banking structure such as a railway or a runway is created, the ground behind the slope, or the ground around the tunnel.

図１及び図２に示すように、本発明の装置２０は、地盤Ａ内の所定深さ位置に配置される共に上端側２１ａが地上まで延びて配置される管体２１と、前記管体２１の開放された下端側２１ｂに設けたフィルタ部２２と、前記管体２１の閉鎖された上端側に取り付けられる圧力センサー２４とを備えている。   As shown in FIGS. 1 and 2, the device 20 of the present invention includes a tubular body 21 that is disposed at a predetermined depth in the ground A and that has an upper end 21 a extending to the ground, and the tubular body 21. The filter part 22 provided in the open | released lower end side 21b, and the pressure sensor 24 attached to the closed upper end side of the said tubular body 21 are provided.

管体２１は、間隙水が自由に出入り可能なチューブ状物であって、地盤Ａ内にマンドレルなどの装置によって圧入でき、かつ地盤の圧力に対抗できる程度の剛性を備えたものが好ましい。具体的には塩ビ管などのフレキシブル管を挙げることができる。また、管の補強または保護を目的として管周りに樹脂層を設けたり、剛性枠や鞘管で覆ったりした二重管構造のものも管体２１として用いることができる。   The tube body 21 is preferably a tube-like object in which pore water can freely enter and exit, and is preferably provided with rigidity enough to press-fit into the ground A by a device such as a mandrel and to counteract the pressure of the ground. Specifically, flexible pipes, such as a vinyl chloride pipe, can be mentioned. A tube 21 having a double tube structure in which a resin layer is provided around the tube for the purpose of reinforcing or protecting the tube, or covered with a rigid frame or a sheath tube can also be used.

管体２１の下端側２１ｂは開放されており、該管体２１を地盤Ａ内の所定深さ位置に配置したとき、管体２１内には地盤Ａ内の間隙水が入り込み、その間隙水の水面は圧力に従って地下水高さまで上昇するようになっている。   The lower end side 21b of the tubular body 21 is open, and when the tubular body 21 is disposed at a predetermined depth position in the ground A, pore water in the ground A enters the tubular body 21, and the pore water is The water surface rises to the groundwater level according to the pressure.

また、管体２１の開放された下端側２１ｂにはフィルタ部２２が設けられており、管体２１内に土砂等の進入が阻止されるようになっている。フィルタ部２２としては、例えばポーラスストーンや籠などを挙げることができ、その表面を布や透水性シートで覆うことでフィルタ部２２の目詰まりを防ぐようにすることもできる。   Moreover, the filter part 22 is provided in the open | released lower end side 21b of the pipe body 21, and entry of earth and sand etc. is prevented in the pipe body 21. As shown in FIG. Examples of the filter part 22 include a porous stone and a wrinkle. The surface of the filter part 22 is covered with a cloth or a water-permeable sheet, so that the filter part 22 can be prevented from being clogged.

管体２１の上端側２１ａは地上まで延びて配置される。そして、管体２１の下端側２１ｂのフィルタ部２２を通して間隙水圧に従って押し上げられた前記間隙水の水面との間に空気溜２３が形成されるように長さが調整されるようになっている。この管体２１の上端側２１ａにはキャップ２５が取り付けられて閉塞されるようになっている。尚、図１に示す例では、管体２１の上端側２１ａは、地盤Ａと盛土との境界に沿って側方まで延ばされた後、地盤Ａ上面から立ち上げるように配置される。   The upper end side 21a of the tubular body 21 is arranged extending to the ground. And the length is adjusted so that the air reservoir 23 is formed between the water surface of the said pore water pushed up according to the pore water pressure through the filter part 22 of the lower end side 21b of the pipe body 21. As shown in FIG. A cap 25 is attached to the upper end side 21 a of the tube body 21 so as to be closed. In the example shown in FIG. 1, the upper end side 21 a of the tube body 21 is arranged so as to rise from the upper surface of the ground A after extending to the side along the boundary between the ground A and the embankment.

この管体２１の上端側２１ａには開口（図示しない）が設けられており、この開口（図示しない）を覆うように圧力センサー２４が取り付けられている。圧力センサー２４の受圧部２４ａは、前記開口（図示しない）の位置に配されて、該受圧部２４ａが空気溜２３内に露出するようになっている。そして、地盤Ａ内の間隙水圧が変動すると、その圧力に従って地盤Ａ内に配置された管体２１内に入り込んだ間隙水の水位が上昇又は降下する。地盤Ａ内の間隙水圧の変動に伴って間隙水の水位が上昇又は降下すると、これに従って空気溜２３内の空気の圧力が高くなったり低くなったりする。空気溜２３内に露出するように配されている圧力センサー２４の受圧部２４ａはこの空気圧の変化を捉えるのである。すなわち地盤Ａ内の間隙水圧の変動は、管体２１内の間隙水の水位の上昇又は降下として現れ、その間隙水の水位の上昇又は降下は、空気溜２３内の空気を膨張又は収縮させ、空気溜２３内の空気圧を変化させるので、この空気圧の変化を測定することで、地盤Ａ内の間隙水圧の変動を把握することができるのである。尚、圧力センサーとしては、特に限定されず、市販されているものを用いることができる。   An opening (not shown) is provided in the upper end side 21a of the tube body 21, and a pressure sensor 24 is attached so as to cover the opening (not shown). The pressure receiving portion 24 a of the pressure sensor 24 is disposed at the position of the opening (not shown) so that the pressure receiving portion 24 a is exposed in the air reservoir 23. And if the pore water pressure in the ground A fluctuates, the water level of the pore water that has entered the pipe body 21 arranged in the ground A will rise or fall according to the pressure. When the water level of the pore water rises or falls with the fluctuation of the pore water pressure in the ground A, the pressure of the air in the air reservoir 23 increases or decreases accordingly. The pressure receiving portion 24a of the pressure sensor 24 arranged so as to be exposed in the air reservoir 23 captures the change in the air pressure. That is, the fluctuation of the pore water pressure in the ground A appears as an increase or decrease in the level of the pore water in the pipe body 21, and the increase or decrease in the level of the pore water causes the air in the air reservoir 23 to expand or contract, Since the air pressure in the air reservoir 23 is changed, the variation in the pore water pressure in the ground A can be grasped by measuring the change in the air pressure. In addition, it does not specifically limit as a pressure sensor, What is marketed can be used.

図１に示す例では、圧力センサー２４によって測定される空気溜２３内の空気圧の変化を電気信号に変換し、無線で管理用コンピュータ２６に送信されるようにしており、これにより、地盤Ａ内の間隙水圧の変動がリアルタイムでコンピュータ管理できるようになっている。   In the example shown in FIG. 1, the change in air pressure in the air reservoir 23 measured by the pressure sensor 24 is converted into an electrical signal and transmitted to the management computer 26 wirelessly. Fluctuation in pore water pressure can be managed by computer in real time.

尚、間隙水中に溶存する空気は、空気溜２３内の空気が収縮すると、同時に管体２１内の間隙水中の溶存空気が脱気され、管体２１の上端側２１ａの空気溜２３内に集まるようになるので、間隙水中の溶存空気が、間隙水圧の変動の把握に悪影響を与えることはない。また、管体２１の上端側２１ａは、地上に配置されるため、その空気溜２３内の空気は、太陽熱などの影響を受けて膨張又は収縮することが考えられる。しかし、空気溜２３内の空気量は少ないため、測定結果に直接影響する恐れはない。より精度の高い測定を行うためには、管体２１の上端側２１ａを断熱材などで覆うことが望ましい。   When the air in the air reservoir 23 contracts, the dissolved air in the interstitial water is simultaneously degassed and collected in the air reservoir 23 on the upper end side 21a of the tubular body 21. Therefore, the dissolved air in the pore water does not adversely affect the grasp of the fluctuation of the pore water pressure. Moreover, since the upper end side 21a of the tubular body 21 is arrange | positioned on the ground, it is possible that the air in the air reservoir 23 expands or contracts under the influence of solar heat or the like. However, since the amount of air in the air reservoir 23 is small, there is no possibility of directly affecting the measurement result. In order to perform measurement with higher accuracy, it is desirable to cover the upper end side 21a of the tube body 21 with a heat insulating material or the like.

次に、図３に示す形態について説明する。間隙水圧の測定は、地盤Ａ内の所定深さ位置に複数の管体２１を間隔を置いて配置するなど、測定点を多くすればするほど、より精度の高い測定結果を得ることができ、信頼性はより高まる。しかし、管体２１毎に圧力センサー２４を取り付け場合、測定点の数だけの圧力センサーが必要となり、その分コストも高くなる。   Next, the form shown in FIG. 3 will be described. For the measurement of pore water pressure, a more accurate measurement result can be obtained as the number of measurement points is increased, for example, a plurality of pipe bodies 21 are arranged at intervals in a predetermined depth position in the ground A. Reliability is further increased. However, when the pressure sensor 24 is attached to each tube body 21, pressure sensors corresponding to the number of measurement points are required, and the cost is increased accordingly.

図３に示す形態は、地盤Ａ内の所定深さ位置に複数の管体２１を間隔を置いて配置し、これら複数の管体２１の各上端側２１ａを１つの圧力センサー２４にまとめて取り付けることで、１つの圧力センサー２４で複数の各管体２１の上端側２１ａに形成される空気溜（図示しない）内の空気圧の変化を測定できるようにしたものである。図３に示すように、複数の管体２１の各上端側２１ａを１つの圧力センサー２４にまとめて取り付けた場合、使用する圧力センサーの数は大幅に削減できるというメリットがある。尚、このような態様に使用する圧力センサーとしては、例えば複数の各管体２１の上端側２１ａに形成される空気溜（図示しない）内の空気圧の変化を各管体２１毎に順に繰り返して測定し、データ化できるようにしたものなどを挙げることができる。   In the form shown in FIG. 3, a plurality of pipe bodies 21 are arranged at intervals in a predetermined depth position in the ground A, and each upper end side 21 a of the plurality of pipe bodies 21 is attached to a single pressure sensor 24. Thus, a single pressure sensor 24 can measure a change in air pressure in an air reservoir (not shown) formed on the upper end side 21a of each of the plurality of tubular bodies 21. As shown in FIG. 3, when the upper end sides 21a of the plurality of tube bodies 21 are attached to one pressure sensor 24, there is an advantage that the number of pressure sensors to be used can be greatly reduced. In addition, as a pressure sensor used for such an aspect, the change of the air pressure in the air reservoir (not shown) formed in the upper end side 21a of each pipe body 21 is repeated in order for each pipe body 21, for example. Examples include those that can be measured and converted into data.

次に、本発明の装置を軟弱地盤の改良工法に適用した例について説明する。図１に示す改良工法は、改良する軟弱地盤（改良地盤）Ａ中に真空圧を負荷することで、前記改良地盤Ａ中に改良地盤周辺部Ｂと隔離された減圧領域を造り出すものであり、複数の鉛直ドレーン材３１を上端部を残して地盤Ａ中に所定の間隔をおいて打設することにより地盤Ａ中に多数の鉛直排水壁を造成し、前記鉛直ドレーン材３１の上端部と接触するように真空タンク３３を介して真空ポンプ３４に連結した水平ドレーン材３２を配置し、次いで、地盤Ａ上を前記鉛直ドレーン材３１の上端部及び水平ドレーン材３２とともに気密シート３５で覆い、この後、前記真空ポンプ３４を作動させる工程からなる。   Next, an example in which the apparatus of the present invention is applied to an improvement method for soft ground will be described. The improved construction method shown in FIG. 1 is to create a reduced pressure region isolated from the improved ground periphery B in the improved ground A by applying a vacuum pressure to the soft ground (improved ground) A to be improved, A plurality of vertical drainage materials 31 are placed in the ground A at predetermined intervals while leaving the upper end portions, thereby creating a large number of vertical drainage walls in the ground A and making contact with the upper end portions of the vertical drain materials 31. The horizontal drain material 32 connected to the vacuum pump 34 via the vacuum tank 33 is arranged so that the ground A is covered with an airtight sheet 35 together with the upper end portion of the vertical drain material 31 and the horizontal drain material 32. Thereafter, the process includes operating the vacuum pump 34.

真空ポンプ３４からの真空圧は真空タンク３３を経てこれに接続する水平ドレーン材３２へと伝達され、改良地盤Ａの表層は負圧状態となる。さらに改良地盤Ａの表層が負圧状態となることで、改良地盤Ａ中の間隙水圧との間には差が生じ、この圧力差によって鉛直ドレーン材３１によって軟弱地盤Ａ中に造成された鉛直排水壁を通して地盤Ａ中の水と空気とが地盤Ａ表層へと吸い出され、地盤Ａ外へ排出される。この結果、改良地盤Ａ中も負圧状態となり、真空度が高くなる。   The vacuum pressure from the vacuum pump 34 is transmitted through the vacuum tank 33 to the horizontal drain material 32 connected thereto, and the surface layer of the improved ground A is in a negative pressure state. Furthermore, since the surface layer of the improved ground A is in a negative pressure state, a difference is generated between the pore water pressure in the improved ground A, and the vertical drainage created in the soft ground A by the vertical drain material 31 due to this pressure difference. Water and air in the ground A are sucked out to the surface layer of the ground A through the wall and discharged to the outside of the ground A. As a result, the improved ground A is also in a negative pressure state, and the degree of vacuum is increased.

こうして略真空となった改良地盤Ａを大気圧が荷重となって抑え付けることになるため、この荷重によって変動する改良地盤Ａ中の間隙水圧を測定することで、改良地盤Ａに加わる上載荷重が把握できるのである。地盤Ａの沈下は、該地盤Ａに加わる上載荷重により生じることから、荷重の大小を把握することで、地盤Ａの沈下終了を判断する材料を得ることができるのである。尚、地盤Ａの沈下終了を判断する材料には、地盤に対する上積荷重のほかに、地盤の沈下量や間隙水の排水量があり、これらを総合して地盤の沈下終了を判断することになる。   In this way, the improved ground A, which has become substantially vacuum, is suppressed by atmospheric pressure as a load. Therefore, by measuring the pore water pressure in the improved ground A that fluctuates due to this load, the upper load applied to the improved ground A is increased. You can figure it out. Since the subsidence of the ground A is caused by an overload applied to the ground A, it is possible to obtain a material for determining the end of the subsidence of the ground A by grasping the magnitude of the load. In addition to the upper load on the ground, the material for determining the end of subsidence of ground A includes the amount of subsidence of the ground and the amount of drainage of pore water, and these are combined to determine the end of subsidence of the ground. .

尚、図１に示す例では、間隙水圧の測定点が、地盤Ａの最深部、中間部、表層部となるように、管体２１の長さを調整して配置している。また、地盤Ａ内の所定深さ位置に複数の管体２１を間隔を置いて配置し、図３に示すように複数の管体２１の各上端側２１ａを１つの圧力センサー２４にまとめて取り付けることで、コストの低減化を図ると共により精度の高い測定結果を得ることができるようになっている。   In the example shown in FIG. 1, the length of the tubular body 21 is adjusted so that the measurement points of the pore water pressure are the deepest part, the middle part, and the surface layer part of the ground A. Further, a plurality of tubes 21 are arranged at predetermined depth positions in the ground A at intervals, and each upper end side 21a of the plurality of tubes 21 is attached to one pressure sensor 24 as shown in FIG. As a result, the cost can be reduced and a more accurate measurement result can be obtained.

次に、地下埋設物が埋設される地盤や盛土構造物が造成される地盤の動態把握方法に本発明の装置を適用した例について説明する。近年、地下水の過剰揚水によって地下水位が低下し、地盤の沈下を引き起こす例が数多く報告されている。沈下を引き起こした地盤中に例えば電話線や上水道などのパイプやケーブルといった地下埋設物が埋設されていたならば、或いはその地盤上に高速道路、堤防道路、鉄道、滑走路などの盛土構造物が造成されていたならば、これら地下埋設物や盛土構造物が大きな損傷を受け、その機能が失われた場合、国民生活に多大な被害を与えることになる。   Next, an example in which the apparatus of the present invention is applied to a ground grasping method for a ground in which an underground buried object is buried or a ground structure in which an embankment structure is created will be described. In recent years, there have been many reports of groundwater subsidence caused by excessive groundwater pumping and ground subsidence. If underground structures such as telephone lines and water pipes and cables are buried in the ground that caused the settlement, or there are embankment structures such as highways, embankment roads, railways, and runways. If constructed, these underground structures and embankment structures will be severely damaged and their function will be lost.

このため、これら地下埋設物が埋設される地盤や盛土構造物を造成する地盤は、埋設前又は造成前に十分に地盤の調査がなされるが、地下水の過剰揚水による地下水位の低下に伴う地盤の沈下など、事後的に生じる地盤の沈下は予測困難である。   For this reason, the ground on which these underground buried objects are buried and the ground on which embankment structures are to be built are thoroughly investigated before being buried or created, but the ground due to the groundwater level drop due to excessive pumping of groundwater Subsequent ground subsidence, such as subsidence, is difficult to predict.

そこで、そのような地盤内には圧力センサーを設置して該地盤の沈下量を測定することで、地下埋設物や盛土構造物が地盤の変動に伴って損傷を受けるのを未然に察知できる監視システムが提案されている。ところが、圧力センサーの設置場所を電話線や上水道などの地下埋設物が埋設される地盤内や高速道路などの盛土構造物を造成する地盤内であって、地盤の変動、沈下によって被害が予想される場所に限ったとしても、そのエリヤは広く、そのようなシステムを導入するには、圧力センサーの設置作業など、莫大な費用が予測される。   Therefore, by installing a pressure sensor in such ground and measuring the amount of settlement of the ground, it is possible to detect in advance that underground buried objects and embankment structures will be damaged due to ground changes A system has been proposed. However, the place where the pressure sensor is installed is in the ground where underground structures such as telephone lines and waterworks are buried, and in the ground where embankment structures such as expressways are built, and damage is expected due to ground fluctuation and settlement. Even if it is limited to a certain area, the area is wide and enormous costs such as the installation work of the pressure sensor are expected to introduce such a system.

本発明の装置を採用した場合、低コストでその監視システムを実現することができる。図４は、地下埋設物が地盤の変動に伴って損傷するのを未然に察知する手段として本発明の装置を適用した例を示すものである。装置２０は、地盤Ａ内の地下埋設物４１近傍に配置される。地下水の低下を原因として地盤Ａの変動が生じた場合、管体２１内に入り込む間隙水の水位の上昇又は降下として現れる。間隙水の水位の上昇又は降下は、図２に示すように空気溜２３内の空気を膨張又は収縮させ、空気圧の変化させる。このため、この空気圧の変化を測定することで、地盤Ａ内の間隙水圧の変動を把握でき、地下埋設物４１が地盤Ａの変動に伴って損傷するのを未然に察知することができるのである。   When the apparatus of the present invention is employed, the monitoring system can be realized at low cost. FIG. 4 shows an example in which the apparatus of the present invention is applied as means for detecting in advance that an underground buried object will be damaged as the ground changes. The device 20 is disposed in the vicinity of the underground buried object 41 in the ground A. When the ground A fluctuates due to a decrease in groundwater, it appears as an increase or decrease in the level of pore water entering the pipe body 21. The rise or fall of the water level of the pore water causes the air in the air reservoir 23 to expand or contract and change the air pressure as shown in FIG. For this reason, by measuring the change in the air pressure, it is possible to grasp the variation in the pore water pressure in the ground A, and to detect in advance that the underground buried object 41 is damaged due to the variation in the ground A. .

図４に示す例では、管体２１の上端側に設けた圧力センサー２４によって測定される空気溜内の空気圧の変化が電気信号に変換され、無線で管理用コンピュータ２６に送信される。この結果、地盤Ａの変動がリアルタイムでコンピュータ管理できるようになっている。   In the example shown in FIG. 4, the change in air pressure in the air reservoir measured by the pressure sensor 24 provided on the upper end side of the tube body 21 is converted into an electric signal and transmitted to the management computer 26 wirelessly. As a result, the fluctuation of the ground A can be managed in real time by the computer.

尚、図４に示す例では、間隙水圧の測定点が、地盤Ａの最深部、中間部、表層部となるように、管体２１の長さを調整し配置している。また、地盤Ａ内の所定深さ位置に複数の管体２１を間隔を置いて配置し、図３に示すように複数の管体２１の各上端側２１ａを１つの圧力センサー２４にまとめて取り付けることで、コストの低減化を図ると共により精度の高い測定結果を得ることができるようにしている。   In the example shown in FIG. 4, the length of the tubular body 21 is adjusted and arranged so that the pore water pressure measurement points are the deepest part, the middle part, and the surface layer part of the ground A. Further, a plurality of tubes 21 are arranged at predetermined depth positions in the ground A at intervals, and each upper end side 21a of the plurality of tubes 21 is attached to one pressure sensor 24 as shown in FIG. Thus, the cost can be reduced and a more accurate measurement result can be obtained.

図５は、盛土構造物が地盤の変動に伴って損傷するのを未然に察知する手段として本発明の装置を適用した例を示すものである。図５に示す例では、道路５１下の地盤Ａ内に複数の管体２１を間隔を置いて、また深さを変えて配置している。また図４に示す例と同じく、複数の管体２１の各上端側２１ａを１つの圧力センサー２４にまとめて取り付けることで、コストの低減化を図ると共により精度の高い測定結果を得ることができるようにしている。   FIG. 5 shows an example in which the apparatus of the present invention is applied as means for detecting in advance that the embankment structure is damaged as the ground changes. In the example shown in FIG. 5, a plurality of pipe bodies 21 are arranged in the ground A under the road 51 at intervals and at different depths. Similarly to the example shown in FIG. 4, by attaching the upper end sides 21 a of the plurality of tube bodies 21 together to one pressure sensor 24, it is possible to reduce costs and obtain more accurate measurement results. I am doing so.

図４に示す例と同様に、地下水の低下を原因として地盤Ａの変動が生じた場合、管体２１内に入り込む間隙水の水位の上昇又は降下として現れる。間隙水の水位の上昇又は降下は、図２に示すように空気溜２３内の空気を膨張又は収縮させ、空気圧の変化させる。このため、この空気圧の変化を測定することで、地盤Ａ内の間隙水圧の変動を把握でき、道路５１（盛土構造物）が地盤Ａの変動に伴って損傷するのを未然に察知できるようにしている。   Similar to the example shown in FIG. 4, when the ground A fluctuates due to a decrease in groundwater, it appears as an increase or decrease in the level of pore water entering the pipe body 21. The rise or fall of the water level of the pore water causes the air in the air reservoir 23 to expand or contract and change the air pressure as shown in FIG. Therefore, by measuring the change in the air pressure, it is possible to grasp the fluctuation of the pore water pressure in the ground A and to detect in advance that the road 51 (the embankment structure) is damaged due to the fluctuation of the ground A. ing.

図５に示す例では、管体２１の上端側に設けた圧力センサー２４によって測定される空気溜内の空気圧の変化が電気信号に変換され、無線で管理用コンピュータ２６に送信される。この結果、地盤Ａの変動がリアルタイムでコンピュータ管理できるようになっている。   In the example shown in FIG. 5, a change in air pressure in the air reservoir measured by the pressure sensor 24 provided on the upper end side of the tube body 21 is converted into an electric signal and transmitted to the management computer 26 wirelessly. As a result, the fluctuation of the ground A can be managed in real time by the computer.

尚、本発明は、図面に示した例に限定されず、例えば本発明の装置とＧＰＳを組み合わせて、各測定点における絶対沈下量を測定するなど、特許請求の範囲に記載した範囲で自由に変更して実施することができる。   The present invention is not limited to the examples shown in the drawings. For example, the apparatus according to the present invention and GPS are combined to measure the absolute settlement at each measurement point. It can be changed and implemented.

２１ ・・・管体
２１ａ ・・・上端側
２１ｂ ・・・下端側
２２ ・・・フィルタ部
２３ ・・・空気溜
２４ ・・・圧力センサー
４１ ・・・地下埋設物
５１ ・・・盛土構造物
Ａ ・・・地盤 21 ... Tube 21a ... Upper end side 21b ... Lower end side 22 ... Filter part 23 ... Air reservoir 24 ... Pressure sensor 41 ... Underground object 51 ... Embankment structure A: Ground

Claims (8)

地盤内の間隙水圧を測定する装置であって、
地盤内の所定深さ位置に配置される共に上端側が地上まで延びて配置される管体と、 前記管体の開放された下端側に設けたフィルタ部と、
前記管体の閉鎖された上端側に取り付けられる圧力センサーと、
を備えており、前記管体の上端側には前記フィルタ部を通して管内に入り込んだ地盤内の間隙水の水面との間に空気溜が形成されるようになっており、
前記管体の上端側に形成される空気溜内には圧力センサーの受圧部が露出するように配置されており、この圧力センサーの受圧部によって前記地盤内の間隙水圧の変動によって変化する前記管内に入り込んだ間隙水の水位の上昇又は降下による前記空気溜内の空気圧の変化を測定するようにしたことを特徴とする間隙水圧測定装置。 A device for measuring pore water pressure in the ground,
A tubular body that is disposed at a predetermined depth position in the ground and that has an upper end extending to the ground, and a filter portion provided on the opened lower end side of the tubular body;
A pressure sensor attached to the closed upper end of the tube;
And an air reservoir is formed between the upper surface of the tube body and the surface of pore water in the ground that has entered the tube through the filter portion.
A pressure receiving part of a pressure sensor is disposed so as to be exposed in an air reservoir formed on the upper end side of the pipe body, and the pressure receiving part of the pressure sensor changes the internal pressure of the pipe that changes due to fluctuations in pore water pressure in the ground. A pore water pressure measuring device characterized in that a change in air pressure in the air reservoir due to an increase or decrease in the level of pore water that has entered is measured. 地盤内の所定深さ位置に複数の管体が間隔を置いて配置され、前記複数の管体の上端側が１つの圧力センサーにまとめて取り付けられており、前記１つの圧力センサーによって前記複数の各管体の上端側に形成される空気溜内の空気圧が測定されるようにしたことを特徴とする請求項１に記載の間隙水圧測定装置。   A plurality of tubes are disposed at predetermined depth positions in the ground at intervals, and upper ends of the plurality of tubes are collectively attached to one pressure sensor, and each of the plurality of tubes is attached by the one pressure sensor. 2. The pore water pressure measuring device according to claim 1, wherein an air pressure in an air reservoir formed on an upper end side of the tube body is measured. 改良する軟弱地盤内に真空圧を利用して改良地盤周辺部と隔離された減圧領域を造り出し、前記軟弱地盤中の間隙水を排水することで、該軟弱地盤を硬質地盤へと改良する軟弱地盤の改良工法において、前記軟弱地盤に対する上積荷重を把握するために該地盤内に配置される間隙水圧測定手段として用いられることを特徴とする請求項１又は２のいずれかに記載の間隙水圧測定装置。   A soft ground that improves the soft ground to hard ground by creating a decompression area isolated from the periphery of the improved ground using vacuum pressure in the soft ground to be improved and draining pore water in the soft ground 3. The pore water pressure measurement according to claim 1, wherein the pore water pressure measurement means is used as a pore water pressure measuring means disposed in the ground for grasping an upper load on the soft ground. apparatus. 地下埋設物が地盤の変動に伴って損傷を受けるのを未然に察知するために、前記地盤内の地下埋設物近傍に配置され、前記地盤の変動に伴う間隙水圧の変動を測定するために用いられることを特徴とする請求項１又は２のいずれかに記載の間隙水圧測定装置。   In order to detect in advance that underground objects will be damaged due to ground changes, it is placed near the underground objects in the ground and used to measure the variation of pore water pressure due to the ground changes. The pore water pressure measuring device according to claim 1, wherein the pore water pressure measuring device is provided. 盛土構造物が地盤の変動に伴って損傷を受けるのを未然に察知するために、前記地盤内に配置され、前記地盤の変動に伴う間隙水圧の変動を測定するために用いられることを特徴とする請求項１又は２のいずれかに記載の間隙水圧測定装置。   In order to detect in advance that the embankment structure will be damaged due to ground change, it is arranged in the ground and is used to measure the variation of pore water pressure accompanying the ground change. The pore water pressure measuring device according to claim 1 or 2. 改良する軟弱地盤内に真空圧を利用して改良地盤周辺部と隔離された減圧領域を造り出し、前記軟弱地盤中の間隙水を排水することで、該軟弱地盤を硬質地盤へと改良する軟弱地盤の改良工法において、
前記軟弱地盤に対する上積荷重を把握するために請求項１又は２のいずれかに記載の間隙水圧測定装置を用いたことを特徴とする軟弱地盤の改良工法。 A soft ground that improves the soft ground to hard ground by creating a decompression area isolated from the periphery of the improved ground using vacuum pressure in the soft ground to be improved and draining pore water in the soft ground In the improved construction method,
An improved construction method for soft ground, characterized in that the pore water pressure measuring device according to claim 1 or 2 is used for grasping an upper load on the soft ground. 地下埋設物が地盤の変動に伴って損傷を受けるのを未然に察知するために、前記地盤内の地下埋設物近傍に配置され、前記地盤の変動に伴う間隙水圧の変動を測定するために請求項１又は２のいずれかに記載の間隙水圧測定装置を用いたことを特徴とする地下埋設物が埋設される地盤の動態把握方法。   In order to detect in advance that an underground buried object will be damaged due to ground change, it is arranged in the vicinity of the underground buried object in the ground, and is requested to measure the fluctuation of pore water pressure accompanying the ground change. Item 3. A method for grasping ground dynamics in which underground objects are embedded, wherein the pore water pressure measuring device according to any one of Items 1 and 2 is used. 盛土構造物が地盤の変動に伴って損傷を受けるのを未然に察知するために、前記地盤内に配置され、前記地盤の変動に伴う間隙水圧の変動を測定するために請求項１又は２のいずれかに記載の間隙水圧測定装置を用いたことを特徴とする盛土構造物が造成される地盤の動態把握方法。   In order to detect in advance that the embankment structure will be damaged as a result of the ground change, it is arranged in the ground and is used to measure the variation in pore water pressure due to the ground change. A method for grasping a dynamic state of a ground on which an embankment structure is formed, characterized by using the pore water pressure measuring device according to any one of the above.
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