JPH07233519A - Site permeability testing device, and testing method using it - Google Patents
Site permeability testing device, and testing method using itInfo
- Publication number
- JPH07233519A JPH07233519A JP4778994A JP4778994A JPH07233519A JP H07233519 A JPH07233519 A JP H07233519A JP 4778994 A JP4778994 A JP 4778994A JP 4778994 A JP4778994 A JP 4778994A JP H07233519 A JPH07233519 A JP H07233519A
- Authority
- JP
- Japan
- Prior art keywords
- pressure
- packer
- water
- pipe
- valve
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)
- Geophysics And Detection Of Objects (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、ガス圧力を用いて気密
パイプ内水位を調節する方式の透水試験の改良に関する
ものである。更に詳しく述べると本発明は、試験区間を
設定するパッカーに気密パイプを接続して、ガス圧力に
より気密パイプ内の水位を変化させる手法と、圧力セン
サにより試験区間圧力を検出する手法とを組み合わせ、
検出圧力の経時変化から地層の透水係数を求める装置に
おいて、気密パイプに遮断弁を設置し、該遮断弁を閉止
状態とすることによって、短時間で平衡水位（水頭）を
測定できるように工夫した技術に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a water permeation test in which the water level in an airtight pipe is adjusted by using gas pressure. More specifically, the present invention connects the airtight pipe to the packer for setting the test section, and combines the method of changing the water level in the airtight tube by the gas pressure and the method of detecting the test section pressure by the pressure sensor,
In the device for determining the hydraulic conductivity of the formation from the change in the detected pressure with time, a shutoff valve was installed in the airtight pipe, and the shutoff valve was closed to measure the equilibrium water level (head) in a short time. It is about technology.
【０００２】この現場透水試験は、各種の土木建築工事
に先立って、あるいは種々の科学的要求によって地層内
にボーリング孔を掘削して行う地下水調査の分野におい
て有用である。特に、透水係数ｋが１０-5cm／sec のオ
ーダー以下の難透水性の地層での現場透水試験に有効で
ある。This in-situ water permeability test is useful in the field of groundwater investigation performed before various civil engineering and construction works or by excavating a boring hole in the formation according to various scientific requirements. In particular, it is effective for an in-situ permeability test in a poorly permeable stratum having a permeability coefficient k of the order of 10 -5 cm / sec or less.
【０００３】[0003]
【従来の技術】地層の透水係数を求めるための従来技術
としては、ＪＦＴ試験と呼ばれる方法がある。これには
中心部を縦貫する通水管の上端にトリップ弁を設けたパ
ッカーを用いる。このパッカーに地上まで達するパイプ
を接続してボーリング孔内の所定の深さに降ろす。その
際、トリップ弁は閉じた状態としておく。また前記パイ
プ内の水位を測定するため、多数の電極を所定の間隔で
配設した水位検出装置を挿入する。ボーリング孔内をパ
ッカーで遮水状態にした後、地上からメッセンジャーを
落下させトリップ弁を開放する。すると、ボーリング孔
のパッカーより下部の地層の透水性によって決まる速度
で、パイプ内を水が上昇し、その水位変化を経時的に電
極と導電率計で測定することにより透水係数が求まる。2. Description of the Related Art As a conventional technique for obtaining the hydraulic conductivity of a formation, there is a method called JFT test. For this, a packer with a trip valve installed at the upper end of a water pipe running vertically through the center is used. A pipe reaching the ground is connected to this packer and lowered to a predetermined depth in the boring hole. At that time, keep the trip valve closed. Further, in order to measure the water level in the pipe, a water level detecting device having a large number of electrodes arranged at predetermined intervals is inserted. After blocking the inside of the boring hole with a packer, drop the messenger from the ground and open the trip valve. Then, the water rises in the pipe at a speed determined by the permeability of the formation below the packer in the borehole, and the permeability coefficient can be obtained by measuring the change in the water level over time with an electrode and a conductivity meter.
【０００４】このＪＦＴ法は、比較的精度よく、深さ数
十ｍまでの地層の透水性を測定できる唯一の試験方法と
して利用されてきた。しかし近年、各種の事情から、更
に大深度での透水性の測定が要求されるようになってき
ており、ＪＦＴ試験では以下のような点で、これらの要
望に応えるには限界がある。 深度が大きくなるとトリップ弁の開放が困難となる。
またボーリング孔内にパッカーを挿入して試験を行う
と、パイプ内に水が入るため、取り出してトリップ弁を
閉じ、挿入し直さない限り再び試験を行うことはできな
い。 トリップ弁はパッカー直上にあるため、バルブを開放
した瞬間、ボーリング孔壁にほぼその深度の水圧が孔の
内側に向かって発生する。そのため孔壁が破壊されてし
まうことがあり、精度のよい測定ができなくなる虞れが
ある。 パイプ内に挿入した多数の電極によって水位の変化を
検知できるが、電極は間隔をおいて設けられているので
連続的な測定が行えない。従って、特に水位の変化速度
が小さいときには大きな測定誤差が生じることになる。The JFT method has been used as the only test method capable of relatively accurately measuring the water permeability of a formation up to a depth of several tens of meters. However, in recent years, due to various circumstances, measurement of water permeability at a greater depth has been required, and the JFT test has a limit in meeting these demands in the following points. As the depth increases, it becomes difficult to open the trip valve.
Also, when a packer is inserted into the boring hole and a test is performed, water enters the pipe, so the test cannot be performed again unless it is taken out, the trip valve is closed, and the pipe is inserted again. Since the trip valve is right above the packer, the water pressure of almost the same depth is generated in the borehole wall toward the inside of the hole the moment the valve is opened. Therefore, the hole wall may be destroyed, and accurate measurement may not be possible. A large number of electrodes inserted in the pipe can detect changes in the water level, but since the electrodes are provided at intervals, continuous measurement cannot be performed. Therefore, particularly when the rate of change of the water level is small, a large measurement error will occur.
【０００５】そこで上記のような欠点を解消し、測定深
度に影響されず、繰り返し試験を行うことができ、また
孔壁の破壊が生じず地質の強弱に自在に対応でき、連続
的な測定を簡便に且つ高精度で行える技術として、本発
明者等は先に「地層の透水試験方法及びその装置」（特
開平２−３０４１１２号公報）を提案した。これは、水
圧検出パッカーとそれに接続した気密パイプを用い、ガ
ス圧力により気密パイプ内の水位を変化させる手法と、
圧力センサにより試験区間圧力を直接検出する手法とを
組み合わせたものである。Therefore, the above-mentioned drawbacks are solved, the test can be repeated without being affected by the measurement depth, the hole wall is not destroyed, and the geological strength can be freely controlled, and continuous measurement can be performed. As a technique that can be performed simply and with high accuracy, the present inventors have previously proposed “a method for testing water permeability of a formation and its apparatus” (Japanese Patent Laid-Open No. 2-304112). This uses a water pressure detection packer and an airtight pipe connected to it, and a method of changing the water level in the airtight pipe by gas pressure,
This is a combination of a method of directly detecting the test section pressure with a pressure sensor.
【０００６】透水試験装置は、次のような構成である。
パッカーの中心部を縦貫する通水管の上部に気密パイプ
を接続して、上端を地上まで立ち上げる。気密パイプの
上部に切換弁を設けて、地上の加圧ガス源側又は大気側
に切り換え可能とする。そしてパッカーで区切られる試
験区間の水圧を検出する圧力センサと、その検出信号を
記録する圧力記録装置を設ける。The water permeability test apparatus has the following structure.
Connect an airtight pipe to the upper part of the water pipe that runs vertically through the center of the packer and raise the upper end to the ground. A switching valve is provided above the airtight pipe to enable switching to the pressurized gas source side on the ground or the atmosphere side. A pressure sensor for detecting the water pressure in the test section divided by the packer and a pressure recording device for recording the detection signal are provided.
【０００７】まずパッカーをボーリング孔内に挿入す
る。パッカー挿入時、切換弁は大気側に開放されてお
り、気密パイプ内は大気圧である。従って気密パイプ内
の水位は自然水位と一致している。次に切換弁を加圧ガ
ス源側に切り換えて気密パイプ内にガス圧を加え、気密
パイプ内の水位を押し下げ、そのガス圧調整により水位
設定を行う。そこでパッカーを膨張させてボーリング孔
を遮水状態にし、試験区間を設定する。その後、切換弁
を操作して気密パイプ内を大気圧に開放する。試験区間
圧力は、ほぼ気密パイプ内水頭まで一旦降下するが、孔
壁からの地下水の供給に応じて気密パイプ内水位は上昇
し、それに伴って試験区間圧力も上昇する。その圧力の
経時的変化を記録して透水係数を求める。First, the packer is inserted into the boring hole. When the packer is inserted, the switching valve is open to the atmosphere side, and the inside of the airtight pipe is at atmospheric pressure. Therefore, the water level in the airtight pipe matches the natural water level. Next, the switching valve is switched to the pressurized gas source side to apply gas pressure to the airtight pipe, push down the water level in the airtight pipe, and adjust the gas pressure to set the water level. Therefore, the packer is inflated to make the boring hole watertight and the test section is set. After that, the switching valve is operated to open the inside of the airtight pipe to the atmospheric pressure. The test section pressure drops to almost the head of the airtight pipe, but the water level in the airtight pipe rises in response to the groundwater supply from the hole wall, and the test section pressure rises accordingly. The change in pressure over time is recorded to determine the hydraulic conductivity.
【０００８】[0008]
【発明が解決しようとする課題】ところで、透水試験で
は平衡水位（水頭）の測定は欠かすことができない。平
衡水位の測定誤差は、透水係数の算出にはそれほど大き
な誤差としては現れないが、これを求めなければ透水係
数を算出できないからである。上記のようなガス圧力に
より初期水位を調整決定する透水試験方法であっても、
特に、地層が難透水性の場合（例えば、透水係数ｋ＝１
０-5cm／sec 以下）には、ボーリング孔内で水位が平衡
に達するまでに非常に長い時間がかかり、測定作業が極
めて困難となっている。因に、透水係数ｋが１０-6cm／
sec のオーダーの場合、平衡水位が得られるまでには約
２日もかかる。そのため難透水性地層の試験では、平衡
水位は概略測定になりがちである。By the way, in the permeability test, the measurement of the equilibrium water level (head) is indispensable. This is because the measurement error of the equilibrium water level does not appear as a large error in the calculation of the hydraulic conductivity, but the hydraulic conductivity cannot be calculated without obtaining it. Even in the permeability test method of adjusting and determining the initial water level by the gas pressure as described above,
Especially when the stratum has poor water permeability (for example, water permeability coefficient k = 1).
To 0 -5 cm / sec or less), it takes a very long time to the water level to reach equilibrium within the borehole, the measurement work has become extremely difficult. The permeability coefficient k is 10 -6 cm /
In the case of sec order, it takes about 2 days until the equilibrium water level is obtained. Therefore, the equilibrium water level tends to be a rough measurement in the test of poorly permeable strata.
【０００９】本発明の目的は、上記のような技術的課題
を解決し、難透水性の地層であっても平衡水位の測定が
短時間で完了し、且つ正確な値が得られ、その結果、透
水試験全体の作業時間を大幅に短縮でき、高精度の測定
結果が得られるような現場透水試験装置及び方法を提供
することである。The object of the present invention is to solve the above-mentioned technical problems and to measure the equilibrium water level in a short time even in a poorly water-permeable formation, and to obtain an accurate value. It is an object of the present invention to provide an on-site water permeability test apparatus and method capable of significantly reducing the working time of the entire water permeability test and obtaining highly accurate measurement results.
【００１０】[0010]
【課題を解決するための手段】本発明は、ガス圧力を用
いて気密パイプ内水位を調節する方式の現場透水試験装
置である。透水試験装置本体は、中心部を縦貫する通水
管を具備しボーリング孔内に挿入されるパッカーと、下
端が前記通水管の上端と連結し上端が地上まで達する気
密パイプと、地上に設置した加圧ガス源と、前記気密パ
イプ内を加圧ガス源側又は大気側に切換え可能な切換え
弁と、前記パッカーで区切られる試験区間の水圧を検出
する圧力センサと、該圧力センサの検出信号を記録する
圧力記録装置とを具備している。本発明の特徴は、この
ような透水試験装置において、内部が通水路となる可撓
性チューブを外側からのガス圧力を用いて圧搾閉塞可能
な構造の遮断弁を、透水試験を行う際に想定される気密
パイプ内の最低水位と前記パッカーとの間の位置に設置
したものである。このパッカーとしては、例えば、中心
部を縦貫する通水管、その外側を取り囲み両端で固着さ
れて加圧ガスの供給により膨張可能なゴムチューブ、該
ゴムチューブ下方の圧力を検出する圧力センサを具備す
る構造の水圧検出パッカーが好ましい。SUMMARY OF THE INVENTION The present invention is an on-site water permeability test apparatus of the type that adjusts the water level in an airtight pipe using gas pressure. The main body of the water permeability tester comprises a packer equipped with a water pipe extending longitudinally through the central part, inserted into the boring hole, an airtight pipe whose lower end is connected to the upper end of the water pipe and whose upper end reaches the ground, and A pressure gas source, a switching valve capable of switching the inside of the airtight pipe to a pressurized gas source side or an atmosphere side, a pressure sensor for detecting water pressure in a test section divided by the packer, and a detection signal of the pressure sensor is recorded. And a pressure recording device. A feature of the present invention is that, in such a water permeability test apparatus, a flexible tube having a water passage inside is assumed to be used when performing a water permeability test on a shutoff valve having a structure that can be squeezed and closed by using gas pressure from the outside. The airtight pipe is installed at a position between the lowest water level and the packer. The packer includes, for example, a water pipe extending vertically through the central portion, a rubber tube surrounding the outside and fixed at both ends and inflatable by supplying pressurized gas, and a pressure sensor for detecting the pressure below the rubber tube. A water pressure detection packer of construction is preferred.
【００１１】パッカーは単一パッカー構造として、該パ
ッカーとボーリング孔底との間を試験区間とする構成で
もよいし、前記パッカーの下方に所定間隔をおいて別の
下部パッカーを配設したダブルパッカー構造として、両
パッカーの間を試験区間とする構成でもよい。ダブルパ
ッカー構造の場合には、遮断弁は上部パッカーの上方に
設ける。The packer may have a single packer structure in which a test section is provided between the packer and the bottom of the boring hole, or a double packer in which another lower packer is arranged below the packer at a predetermined interval. As a structure, a configuration in which a test section is provided between both packers may be used. In the case of the double packer structure, the shutoff valve is installed above the upper packer.
【００１２】本発明で用いる遮断弁としては、ゴムチュ
ーブの上下両端近傍が円錐台状にやや拡開するように、
それぞれテーパ面をもつ外側部材と、それぞれ楔形先端
部をもつ内筒部材とで挾持すると共に、両外側部材の内
面に凹部を設けて、組み合わせた外側部材の内面とゴム
チューブ外面との間に円筒状のガスチャンバーを形成
し、一方の外側部材の内部軸方向に、外部の加圧ガス源
と前記ガスチャンバーとを連通するガス供給路を形成し
た構造がある。チューブはゴム製が好ましいが、軟質合
成樹脂製などでもよい。The shut-off valve used in the present invention is such that the vicinity of the upper and lower ends of the rubber tube is slightly expanded into a truncated cone shape.
An outer member having a tapered surface and an inner cylindrical member having a wedge-shaped tip end are both sandwiched, and recesses are provided on the inner surfaces of both outer members to form a cylinder between the inner surface of the combined outer member and the outer surface of the rubber tube. There is a structure in which a gas chamber is formed in a rectangular shape, and a gas supply path that connects an external pressurized gas source and the gas chamber is formed in the inner axial direction of one outer member. The tube is preferably made of rubber, but may be made of soft synthetic resin.
【００１３】[0013]
【作用】ボーリング孔内において、遮断弁を開放状態の
まま、気密パイプ内に加圧ガスを供給すると、該気密パ
イプ内の水位が下がる。パッカーは、その膨張によって
ボーリング孔の上下間を遮水状態とし、それによって試
験区間を設定する。単一パッカーの場合は、該パッカー
とボーリング孔底との間が試験区間となり、ダブル・パ
ッカーの場合は、両パッカーの間が試験区間となる。気
密パイプ内圧力を大気に開放すると、試験区間圧力は急
激に低下し、該試験区間の地層から地下水が流入して気
密パイプ内の水位が除々に上昇する。圧力センサは、こ
の時の圧力を検出し、圧力記録装置はその経時的変化を
記録する。この試験区間圧力の経時変化から透水係数が
求まる。When the pressurized gas is supplied into the airtight pipe in the boring hole while the shutoff valve is kept open, the water level in the airtight pipe is lowered. Due to the expansion, the packer makes the upper and lower parts of the boring hole water-tight, thereby setting the test section. In the case of a single packer, the test section is between the packer and the bottom of the boring hole, and in the case of a double packer, the test section is between the packers. When the pressure in the airtight pipe is released to the atmosphere, the pressure in the test section rapidly decreases, groundwater flows in from the stratum in the test section, and the water level in the airtight pipe gradually rises. The pressure sensor detects the pressure at this time, and the pressure recording device records the change over time. The hydraulic conductivity can be obtained from the change with time in the test section pressure.
【００１４】透水係数を求める間だけ、試験区間圧力の
経時変化を測定すれば、その後は、測定を続行する必要
はない。遮断弁を閉じると、気密パイプ内を上昇しよう
とする水の流れが阻止されるので、地層からの地下水の
流入は生じず、単に試験区間圧力のみ上昇する。この圧
力は、ほんの僅かの水の流動しか伴わないため速やかに
上昇し、やがて一定の値となる。この一定値が試験区間
の平衡水頭（水位）であり、圧力センサは、この平衡水
頭を検出する。If the change with time in the test zone pressure is measured only while the hydraulic conductivity is obtained, it is not necessary to continue the measurement thereafter. When the shutoff valve is closed, the flow of water trying to rise in the airtight pipe is blocked, so that the inflow of groundwater from the formation does not occur, but only the test section pressure rises. This pressure rapidly rises to a constant value due to the slight flow of water. This constant value is the equilibrium head (water level) in the test section, and the pressure sensor detects this equilibrium head.
【００１５】[0015]
【実施例】図１は本発明に係る現場透水試験装置の一実
施例を示す全体構成図であり、単一のパッカーを用いる
例である。透水試験装置本体は、中心部を縦貫する通水
管１０を具備しボーリング孔１２内に挿入されるパッカ
ー１４と、下端で前記通水管１０に連結し上端が地上ま
で達する気密パイプ１６と、地上に設置した加圧ガス源
１８（例えば窒素ガスボンベ）と、前記気密パイプ１６
内を前記加圧ガス源側又は大気側に切換え可能な三方切
換え弁２０を具備している。更に、前記パッカー１４で
区切られる試験区間の水圧を検出する圧力センサ２２を
設け、該圧力センサ２２の検出信号を記録するために地
上に圧力記録装置２４を設置する。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an overall configuration diagram showing an embodiment of the on-site water permeability test apparatus according to the present invention, which is an example using a single packer. The main body of the water permeability tester comprises a packer 14 having a water pipe 10 extending vertically through a central portion and inserted into a boring hole 12, an airtight pipe 16 connected to the water pipe 10 at a lower end and an upper end reaching the ground, and a ground pipe. The installed pressurized gas source 18 (for example, a nitrogen gas cylinder) and the airtight pipe 16
It is provided with a three-way switching valve 20 capable of switching the inside to the pressurized gas source side or the atmosphere side. Further, a pressure sensor 22 for detecting the water pressure in the test section divided by the packer 14 is provided, and a pressure recording device 24 is installed on the ground to record the detection signal of the pressure sensor 22.
【００１６】前記パッカー１４は、通水管１０の外側を
取り囲み、両端で固着されて加圧ガスの供給により膨張
するゴムチューブからなり、それが膨張してボーリング
孔壁に密着することで、そのパッカー位置でボーリング
孔１２の上下を遮水する構造である。従って、本実施例
では、パッカー１４とボーリング孔底との間が試験区間
となる。ここで圧力センサ２２は該パッカー１４の上端
に取り付けられているが、導水路（破線で示す）２６を
介してパッカー１４の下端と連通しており（パッカー１
４の下端で開口している）、該パッカー１４の下方の圧
力（試験区間の圧力）を検出する。The packer 14 is a rubber tube which surrounds the outside of the water pipe 10 and which is fixed at both ends and expands by the supply of pressurized gas. When the packer 14 expands and comes into close contact with the boring hole wall, the packer 14 It has a structure in which water is blocked above and below the boring hole 12 at a position. Therefore, in this embodiment, the test section is between the packer 14 and the bottom of the boring hole. Here, the pressure sensor 22 is attached to the upper end of the packer 14, but communicates with the lower end of the packer 14 via a water conduit (shown by a broken line) 26 (packer 1
(Opened at the lower end of 4), the pressure below the packer 14 (pressure in the test section) is detected.
【００１７】さて本発明では、内部が通水路となる可撓
性チューブを外側からのガス圧力を用いて圧搾閉塞可能
な構造の遮断弁３０を、透水試験を行う際に想定される
気密パイプ１６内の最低水位と前記パッカー１６との間
の位置に設置しており、この点に特徴がある。遮断弁３
０の詳細を図２に示す。遮断弁３０は、ゴムチューブ３
２の上下両端近傍が円錐台状にやや拡開するように、そ
れぞれ内周面にテーパ面をもつ外側部材３４，３５と、
それぞれ楔形先端部をもつ内筒部材３６，３７とで挾持
する構造である。上下の外側部材３４，３５は、Ｏリン
グシール３８を介して気密的に螺合させ、両外側部材３
４，３５の内周面に凹部４０を設けて、両外側部材３
４，３５の内面とゴムチューブ３２外面との間で円筒状
のガスチャンバーを形成する。凹部４０は、中央部が深
く、上下両端部がテーパー状に浅くなっている断面形状
である。そして、上方の外側部材３４の軸方向にガスチ
ャンバーと連通するガス供給路４２を形成し、加圧ガス
チューブ４４（図１参照）を接続するための接続部４６
を設ける。外部加圧チューブ４４は、地上側で開閉弁４
８を介して加圧ガス源１８に接続する。In the present invention, the shut-off valve 30 having a structure in which the flexible tube having a water passage inside is squeezed and closed by using gas pressure from the outside is used as the airtight pipe 16 which is assumed when conducting the water permeability test. It is installed at a position between the lowest water level and the packer 16, and is characterized by this point. Shut-off valve 3
Details of 0 are shown in FIG. The shutoff valve 30 is a rubber tube 3
2, outer members 34 and 35 each having a tapered surface on the inner peripheral surface so that the vicinity of the upper and lower ends of 2 slightly expands like a truncated cone.
The inner cylinder members 36 and 37 each have a wedge-shaped tip portion and are sandwiched between them. The upper and lower outer members 34, 35 are airtightly screwed together via an O-ring seal 38, so that both outer members 3
The concave portions 40 are provided on the inner peripheral surfaces of the outer peripheral member 4 and the outer peripheral member 3
A cylindrical gas chamber is formed between the inner surfaces of 4, 35 and the outer surface of the rubber tube 32. The recess 40 has a cross-sectional shape in which the central portion is deep and the upper and lower end portions are tapered shallow. Then, a gas supply path 42 communicating with the gas chamber is formed in the axial direction of the upper outer member 34, and a connecting portion 46 for connecting a pressurized gas tube 44 (see FIG. 1).
To provide. The external pressurizing tube 44 is the on-off valve 4 on the ground side.
Connected to the pressurized gas source 18 via 8.
【００１８】ゴムチューブ３２は、ここでは両端が外向
きにやや拡開し、両端部に近くなるほどやや厚めになる
ような成形品を使用しているが、極く単純な円筒ストレ
ート形状であってもよい。その断面の中心に対して１８
０度対称位置に、軸方向に延びる溝（薄肉部）を形成し
て、外部からのガス圧力によって、溝の箇所で折れ曲が
って圧搾し易くする。なお、外側部材３４，３５のテー
パ面に３箇所ずつ断面Ｖ型の円周溝を形成し、外側部材
３４，３５と内筒部材３６，３７とでゴムチューブ３２
の両端を挾持したときに、ゴムを該円周溝に食い込ませ
てずれないようにする。Here, the rubber tube 32 is a molded product in which both ends are slightly expanded outward and the thickness becomes slightly thicker toward both ends, but it is a very simple cylindrical straight shape. Good. 18 to the center of the cross section
A groove (thin-walled portion) extending in the axial direction is formed at a 0-degree symmetrical position so that the groove bends at the groove by the gas pressure from the outside to facilitate pressing. In addition, a circumferential groove having a V-shaped cross section is formed in each of three tapered surfaces of the outer members 34 and 35, and the rubber tubes 32 are formed by the outer members 34 and 35 and the inner tubular members 36 and 37.
When both ends of the are clamped, the rubber bites into the circumferential groove so as not to shift.
【００１９】この遮断弁３０では、ガス供給路４２を軸
方向に形成し、接続部４６も軸方向に引き出しているた
め、側方に突出部分が無い。またゴムチューブ３２の両
端をテーパ面を使用して中心軸に対して斜めに押さえる
構造なので、径方向の押さえ代が小さくてよく、そのた
めに内径（通水路の直径）に対して外径を小さく（細径
化）でき（例えば外径５４mmφ程度）、通常の小口径
（６６mmφ）ボーリング孔での使用が可能となる。また
加圧ガスにより作動させる方式なので、電磁弁などと異
なり大深度でも確実に、且つ容易に開閉させることがで
きる。In this shut-off valve 30, since the gas supply passage 42 is formed in the axial direction and the connecting portion 46 is also drawn out in the axial direction, there is no protruding portion on the side. Further, since both ends of the rubber tube 32 are structured to be pressed obliquely with respect to the central axis by using tapered surfaces, the radial pressing margin may be small, and therefore the outer diameter is smaller than the inner diameter (diameter of the water passage). It can be made thinner (for example, an outer diameter of about 54 mmφ), and can be used in a normal small bore (66 mmφ) boring hole. Further, since it is operated by a pressurized gas, unlike a solenoid valve or the like, it can be opened and closed reliably and easily even at a large depth.
【００２０】本装置による現場透水試験方法について説
明する。基本的な透水試験方法は、前述した従来方法と
同様であってよい。まず遮断弁３０を開放状態とし、且
つ三方切換え弁２０で気密パイプ１６内を大気圧とした
まま、パッカー１４をボーリング孔１２内の所定の深度
まで挿入する。パッカー１４の位置とボーリング孔底と
の間が試験区間となる。次に、三方切換え弁２０を操作
して気密パイプ１６内に加圧ガス源１８から窒素ガスを
供給して水位を自然水位Ｌ0 から透水試験初期水位Ｌ1
まで押し下げる。この透水試験初期水位Ｌ1 は、遮断弁
３０よりも上に位置する。そしてパッカー１４を膨張さ
せて、その位置でボーリング孔１２の上下間を遮水状態
にする。これによって試験区間が設定される。なおパッ
カー１４の膨張は、図示されていないが、地上からチュ
ーブなどを通して供給される加圧ガスによってなされ
る。圧力センサ２２は、試験区間の圧力を検出して、そ
の圧力の経時変化を圧力記録装置２４で記録する。An on-site water permeability test method using this apparatus will be described. The basic water permeability test method may be the same as the conventional method described above. First, the shut-off valve 30 is opened, and the packer 14 is inserted into the boring hole 12 to a predetermined depth while the three-way switching valve 20 keeps the airtight pipe 16 at atmospheric pressure. The test section is between the position of the packer 14 and the bottom of the boring hole. Next, the three-way switching valve 20 is operated to supply nitrogen gas from the pressurized gas source 18 into the airtight pipe 16 so that the water level changes from the natural water level L 0 to the water permeability test initial water level L 1.
Push down. The initial water level L 1 of the water permeability test is located above the shutoff valve 30. Then, the packer 14 is inflated so that the upper and lower portions of the boring hole 12 are in a water-blocking state at that position. This sets the test section. Although not shown, the packer 14 is expanded by a pressurized gas supplied from the ground through a tube or the like. The pressure sensor 22 detects the pressure in the test section and records the change over time of the pressure with the pressure recording device 24.
【００２１】図３は、圧力センサ２２で検出する水頭
（水位）の時間変化の様子を示している。三方切換え弁
２０を操作して、気密パイプ１６内の圧力を大気に開放
する。地層が難透水性の場合には、孔壁からの地下水の
供給が少ないため、気密パイプ１６内の水位は上昇し難
く、圧力検出値は気密パイプ１６内水頭近傍まで急激に
降下する。そして、試験区間の孔壁から徐々に地下水が
流入し、気密パイプ１６内の水位も徐々に上昇するの
で、圧力センサ２２による圧力検出値も徐々に上昇する
ことになる。この水頭の経時変化曲線から透水係数を求
める。それに必要な測定時間Ｔ1 は、数十秒から数十分
程度である。つまり、ある程度綺麗な測定曲線が得られ
れば、それで十分である。そのまま放置しておくと、破
線で示すように、更に平衡水頭に向かって水頭はゆっく
りと上昇し続ける。従来技術では、引き続いてそれを観
測し続けていたのであるが、本発明では、透水係数を求
めるために必要な測定時間Ｔ1 経過後は、遮断弁３０を
閉じてよい。FIG. 3 shows how the water head (water level) detected by the pressure sensor 22 changes with time. The three-way switching valve 20 is operated to open the pressure in the airtight pipe 16 to the atmosphere. When the formation is poorly permeable, the water level in the airtight pipe 16 is unlikely to rise because the amount of groundwater supplied from the hole wall is small, and the pressure detection value rapidly drops to near the waterhead in the airtight pipe 16. Then, since groundwater gradually flows in from the hole wall of the test section and the water level in the airtight pipe 16 also gradually rises, the pressure detection value by the pressure sensor 22 also gradually rises. The hydraulic conductivity is obtained from this temporal change curve of the water head. The measurement time T 1 required for this is about tens of seconds to tens of minutes. In other words, it suffices if a beautiful measurement curve can be obtained to some extent. If left as is, the head continues to rise slowly toward the equilibrium head, as indicated by the broken line. In the prior art, it was continuously observed, but in the present invention, the shutoff valve 30 may be closed after the elapse of the measurement time T 1 required for obtaining the hydraulic conductivity.
【００２２】遮断弁３０を閉じるためには、開閉弁４８
を操作して加圧ガスチューブ４４、接続部４６、及びガ
ス供給路４２を経由してガスチャンバー内に加圧ガスを
供給すればよい。その圧力によってゴムチューブ３２が
両側から偏平に潰れて通水路を遮断する。このようにし
て遮断弁３０を閉じると、気密パイプ１６内を上昇しよ
うとする水の流れが阻止されるので、地層からの地下水
の流入は、水の圧縮率に相当するほんの僅かしか生じ
ず、単に試験区間圧力のみ上昇する。図３に示すよう
に、この圧力上昇は、水の流動がほとんど伴わないため
速やかに生じ、やがて（時間Ｔ2 ）で一定の値となる。
この一定となった圧力が試験区間の平衡水頭（水位）に
他ならない。圧力センサ２２は、この平衡水頭を検出す
る。平衡水頭に達するまでの時間Ｔ2 は、数分〜数十分
程度である。従って、これら透水係数の測定に必要な時
間Ｔ1 及び平衡水頭に達するまでの時間Ｔ2 は、透水性
の大小によって左右されるが、両者合わせても（Ｔ1 ＋
Ｔ2 ）２〜３時間を超えることはない。なお、水頭変化
の測定と平衡水位の測定の順序は逆でもよい。To close the shutoff valve 30, the on-off valve 48
Is operated to supply the pressurized gas into the gas chamber via the pressurized gas tube 44, the connecting portion 46, and the gas supply path 42. Due to the pressure, the rubber tube 32 is flattened from both sides to block the water passage. When the shutoff valve 30 is closed in this way, the flow of water that attempts to rise in the airtight pipe 16 is blocked, so that the inflow of groundwater from the stratum occurs only slightly, which corresponds to the compressibility of water, Only the test zone pressure rises. As shown in FIG. 3, this pressure increase occurs promptly because there is almost no flow of water, and eventually reaches a constant value (time T 2 ).
This constant pressure is the equilibrium head (water level) of the test section. The pressure sensor 22 detects this equilibrium head. The time T 2 until reaching the equilibrium head is several minutes to several tens of minutes. Therefore, the time T 1 required to measure the hydraulic conductivity and the time T 2 required to reach the equilibrium head depend on the magnitude of the water permeability, but both of them (T 1 +
T 2) does not exceed 2-3 hours. The measurement of the change in the head and the measurement of the equilibrium water level may be reversed.
【００２３】図１の例では、装置構成上、圧力センサ２
２をパッカー１４の上方に設けているため、検出される
圧力はパッカー下部の導水口での水圧から圧力センサ２
２までの水頭圧を減じたものとなる。しかし、導水路の
長さは一定であるから、その水頭圧は一定であり、相対
値としてみるならば何ら問題はない。もし必要があれ
ば、前記水頭圧を加算するような補正を行えばよい。In the example shown in FIG. 1, the pressure sensor 2 is used because of the device configuration.
2 is provided above the packer 14, the pressure to be detected depends on the water pressure at the water inlet at the bottom of the packer.
The head pressure up to 2 is reduced. However, since the length of the headrace is constant, its head pressure is constant, and there is no problem if viewed as a relative value. If necessary, a correction may be made to add the hydrohead pressure.
【００２４】上記の試験方法は、試験区間内の圧力が徐
々に回復する際の水頭（水位）変化を求める回復法の場
合であるが、本発明装置は、気密パイプ内の水を試験区
間内に圧送する注水法の場合にも使用できる。更に上記
の実施例では、単一パッカーを用いて、それとボーリン
グ孔底との間に試験区間を設定する例であるが、ダブル
・パッカーにより、ボーリング孔の任意の地点間に試験
区間を設定することもできる。その場合には、前記パッ
カーの下方に所定間隔をおいて下部パッカーを配設して
試験区間を設定し、遮断弁を上部パッカーの上方に設け
ればよい。The above-mentioned test method is a recovery method for obtaining a change in the water head (water level) when the pressure in the test section gradually recovers. It can also be used in the case of the water injection method in which it is pressure-fed. Further, in the above-mentioned embodiment, a single packer is used to set the test section between it and the bottom of the boring hole, but a double packer sets the test section between arbitrary points of the boring hole. You can also In that case, a lower packer may be disposed below the packer at a predetermined interval to set a test section, and a shutoff valve may be provided above the upper packer.
【００２５】[0025]
【発明の効果】本発明は上記のように、内部が通水路と
なる可撓性チューブを外側からのガス圧力を用いて圧縮
閉塞可能な構造の遮断弁を、透水試験を行う際に想定さ
れる気密パイプ内の最低水位と前記パッカーとの間の位
置に設置し、地下水の流動ではなく圧力測定により平衡
水頭（水位）を求めるようにしたので、難透水性の地層
であっても平衡水位の測定が短時間で済み、且つ正確な
値が得られ、透水試験全体の時間が短縮され、且つ結果
の精度を上げることができる。例えば透水係数ｋが１０
-6cm／sec 程度の地層の場合、平衡水位を正確に求める
ためには、従来技術では２日程度必要としたのに対し、
本発明によれば数分〜数十分でよく、作業効率が著しく
向上する。INDUSTRIAL APPLICABILITY As described above, the present invention is envisioned when conducting a water permeability test on a shut-off valve having a structure in which a flexible tube having a water passage inside is compressed and occluded by using gas pressure from the outside. It is installed between the lowest water level in the airtight pipe and the packer, and the equilibrium head (water level) is obtained by pressure measurement instead of groundwater flow. Can be measured in a short time, an accurate value can be obtained, the time required for the entire water permeability test can be shortened, and the accuracy of the result can be improved. For example, the hydraulic conductivity k is 10
In the case of a stratum of about -6 cm / sec, in order to accurately obtain the equilibrium water level, it took about two days in the conventional technology, whereas
According to the present invention, it takes only several minutes to several tens of minutes, and the working efficiency is remarkably improved.
【図１】本発明に係る現場透水試験装置の一実施例を示
す全体説明図。FIG. 1 is an overall explanatory view showing an embodiment of a field permeability test apparatus according to the present invention.
【図２】それに組み込む遮断弁の一例を示す構造図。FIG. 2 is a structural diagram showing an example of a shutoff valve incorporated therein.
【図３】透水試験における水頭（水圧）−経過時間の関
係の一例を示すグラフ。FIG. 3 is a graph showing an example of the relationship between hydrohead (water pressure) and elapsed time in a water permeability test.
１０ 通水管 １２ ボーリング孔 １４ パッカー １６ 気密パイプ １８ 加圧ガス源 ２０ 三方切換え弁 ２２ 圧力センサ ２４ 圧力記録装置 ２６ 導水路 ３０ 遮断弁 10 Water Pipe 12 Boring Hole 14 Packer 16 Airtight Pipe 18 Pressurized Gas Source 20 Three-way Switching Valve 22 Pressure Sensor 24 Pressure Recording Device 26 Water Conduit 30 Shutoff Valve
Claims (4)
ング孔内に挿入されるパッカーと、下端が前記通水管の
上端と連結し上端が地上まで達する気密パイプと、地上
に設置した加圧ガス源と、前記気密パイプ内を加圧ガス
源側又は大気側に切換え可能な切換え弁と、前記パッカ
ーで区切られる試験区間の水圧を検出する圧力センサ
と、該圧力センサの検出信号を記録する圧力記録装置と
を有する透水試験装置において、内部が通水路となる可
撓性チューブを外側からのガス圧力を用いて圧搾閉塞可
能な構造の遮断弁を、透水試験を行う際の気密パイプ内
の最低水位と前記パッカーとの間の位置に設置したこと
を特徴とする現場透水試験装置。1. A packer having a water pipe extending vertically through a central portion, inserted into a boring hole, an airtight pipe having a lower end connected to an upper end of the water pipe and an upper end reaching the ground, and a pressurization installed on the ground. A gas source, a switching valve capable of switching the inside of the airtight pipe to a pressurized gas source side or an atmosphere side, a pressure sensor for detecting water pressure in a test section divided by the packer, and a detection signal of the pressure sensor is recorded. In a water permeability test apparatus having a pressure recording device, a flexible tube having a water passage inside is squeezed with a shut-off valve that can be squeezed and closed using gas pressure from the outside, in an airtight pipe during a water permeability test An on-site water permeability test apparatus, which is installed at a position between the minimum water level and the packer.
別の下部パッカーを配設して、両パッカーによって試験
区間を設定し、遮断弁を上部パッカーの上方に設置した
請求項１記載の現場透水試験装置。2. A site according to claim 1, wherein another lower packer is arranged below the packer at a predetermined interval, a test section is set by both packers, and a shutoff valve is installed above the upper packer. Water permeability test equipment.
が円錐台状にやや拡開するように、それぞれテーパ面を
もつ外側部材と、それぞれ楔形先端部をもつ内筒部材と
で挾持すると共に、両外側部材の内面に凹部を設けて、
組み合わせた両外側部材の内面とゴムチューブ外面との
間でガスチャンバーを形成し、一方の外側部材の軸方向
に、外部の加圧ガス源から前記ガスチャンバーに連通す
るガス供給路を形成した構造をなしている請求項１又は
２記載の現場透水試験装置。3. The shut-off valve is sandwiched between an outer member having a tapered surface and an inner cylindrical member having a wedge-shaped tip end portion so that the vicinity of the upper and lower ends of the rubber tube slightly expands like a truncated cone. , Providing recesses on the inner surfaces of both outer members,
A structure in which a gas chamber is formed between the inner surface of both outer members combined and the outer surface of the rubber tube, and a gas supply path is formed in the axial direction of one outer member to communicate with the gas chamber from an external pressurized gas source. The on-site water permeability test apparatus according to claim 1 or 2, wherein
断弁を開放状態のまま、気密パイプ内に加圧ガスを供給
して水位を下げた後、パッカーを膨張させボーリング孔
の上下を該パッカー位置で遮水状態にして該パッカー下
方に試験区間を設定し、気密パイプ内圧力を大気に開放
して、試験区間圧力の経時変化から透水係数を求め、そ
の後遮断弁を閉止状態にして水頭がほぼ一定になるまで
待ち、この一定となった圧力を平衡水頭とする現場透水
試験方法。4. The apparatus according to any one of claims 1 to 3 is used, while the shutoff valve is kept open, pressurized gas is supplied into the airtight pipe to lower the water level, and then the packer is expanded to raise and lower the boring hole. Set a test section below the packer with a water blocking state at the packer position, open the pressure in the airtight pipe to the atmosphere, determine the hydraulic conductivity from the change over time in the test section, and then close the shutoff valve. Wait until the head becomes almost constant, and then use this constant pressure as the equilibrium head.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4778994A JP3065208B2 (en) | 1994-02-22 | 1994-02-22 | On-site permeability test equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4778994A JP3065208B2 (en) | 1994-02-22 | 1994-02-22 | On-site permeability test equipment |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07233519A true JPH07233519A (en) | 1995-09-05 |
| JP3065208B2 JP3065208B2 (en) | 2000-07-17 |
Family
ID=12785150
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4778994A Expired - Lifetime JP3065208B2 (en) | 1994-02-22 | 1994-02-22 | On-site permeability test equipment |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3065208B2 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010025757A (en) * | 2008-07-18 | 2010-02-04 | Kajima Corp | Tracer testing method |
| CN107765328A (en) * | 2017-12-01 | 2018-03-06 | 黄河勘测规划设计有限公司 | Portable compact type slug test tester |
| CN112630118A (en) * | 2020-11-16 | 2021-04-09 | 苏州开洛泰克科学仪器科技有限公司 | Gas permeability measuring device and measuring method for compact material |
| CN113189289A (en) * | 2021-04-28 | 2021-07-30 | 东北大学 | Hydrodynamic dispersion on-site measuring system and method |
| CN113670789A (en) * | 2021-07-28 | 2021-11-19 | 金石钻探(唐山)股份有限公司 | Method and device for water pressure test |
| CN115872487A (en) * | 2023-02-07 | 2023-03-31 | 华北有色工程勘察院有限公司 | Seepage tailing pond underground water treatment system and method |
-
1994
- 1994-02-22 JP JP4778994A patent/JP3065208B2/en not_active Expired - Lifetime
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010025757A (en) * | 2008-07-18 | 2010-02-04 | Kajima Corp | Tracer testing method |
| CN107765328A (en) * | 2017-12-01 | 2018-03-06 | 黄河勘测规划设计有限公司 | Portable compact type slug test tester |
| CN107765328B (en) * | 2017-12-01 | 2023-08-01 | 黄河勘测规划设计研究院有限公司 | Portable impact micro-water test tester |
| CN112630118A (en) * | 2020-11-16 | 2021-04-09 | 苏州开洛泰克科学仪器科技有限公司 | Gas permeability measuring device and measuring method for compact material |
| CN113189289A (en) * | 2021-04-28 | 2021-07-30 | 东北大学 | Hydrodynamic dispersion on-site measuring system and method |
| CN113670789A (en) * | 2021-07-28 | 2021-11-19 | 金石钻探(唐山)股份有限公司 | Method and device for water pressure test |
| CN115872487A (en) * | 2023-02-07 | 2023-03-31 | 华北有色工程勘察院有限公司 | Seepage tailing pond underground water treatment system and method |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3065208B2 (en) | 2000-07-17 |
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