JP5416661B2 - Swelling test method - Google Patents

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JP5416661B2
JP5416661B2 JP2010149356A JP2010149356A JP5416661B2 JP 5416661 B2 JP5416661 B2 JP 5416661B2 JP 2010149356 A JP2010149356 A JP 2010149356A JP 2010149356 A JP2010149356 A JP 2010149356A JP 5416661 B2 JP5416661 B2 JP 5416661B2
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一三 小林
惣 藤澤
信 竹内
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鹿島建設株式会社
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本発明は、鉱物材料の膨潤性を評価するための膨潤試験方法に関する。   The present invention relates to a swelling test method for evaluating the swelling property of mineral materials.
ベントナイトは水と接触すると吸水して膨潤する鉱物材料である。かかる性質を有するベントナイトは、止水材料として使用されている。例えば、放射性廃棄物処分場や高速道路などの構造物を地下に構築する際、地下水の浸入などを防止する目的で構造物の周囲にベントナイトを含有するバリア層が形成される。止水材料の膨潤性の程度は、バリア層の性能に影響を与えるため、地下構造物を設計するに際し、これを評価するための膨潤試験が実施される。   Bentonite is a mineral material that absorbs and swells when in contact with water. Bentonite having such properties is used as a waterstop material. For example, when a structure such as a radioactive waste disposal site or a highway is built underground, a barrier layer containing bentonite is formed around the structure for the purpose of preventing infiltration of groundwater. Since the degree of swelling of the water-stopping material affects the performance of the barrier layer, a swelling test is performed to evaluate this when designing an underground structure.
下記非特許文献1には、岩石の体積の変位を拘束した状態で膨潤圧を測定する膨潤圧試験方法が記載されている。従来、粒状又は粉状のベントナイトの膨潤性は、非特許文献1に記載の方法に準拠し、以下のようにして評価されていた。まず、ベントナイトを含む試料を圧縮成形して所定の乾燥密度の供試体を得る。この供試体を測定装置内に封入した状態で供試体の上面及び下面の少なくとも一方に水を供給する(図2参照)。これにより膨潤圧を発生させ、ロードセルで膨潤圧を測定する。なお、所定の圧力条件下において供試体に給水して供試体の体積変位量(膨潤量)を測定する膨潤量試験を実施する場合もある。   Non-Patent Document 1 below describes a swelling pressure test method in which the swelling pressure is measured in a state where the displacement of the rock volume is constrained. Conventionally, the swellability of granular or powdered bentonite has been evaluated as follows based on the method described in Non-Patent Document 1. First, a specimen containing bentonite is compression-molded to obtain a specimen having a predetermined dry density. Water is supplied to at least one of the upper surface and the lower surface of the specimen in a state where the specimen is sealed in the measuring apparatus (see FIG. 2). Thus, a swelling pressure is generated, and the swelling pressure is measured with a load cell. In some cases, a swelling amount test is performed in which the specimen is supplied with water under a predetermined pressure condition and the volume displacement (swelling amount) of the specimen is measured.
ところで、従来の膨潤試験は供給された水が供試体内に均一に拡散するのに時間がかかるため、測定に長期の時間を要するだけでなく、計測時間に余裕が無い場合には膨潤圧を過小評価することもあった。鉱物材料の膨潤性や供試体の圧縮度(乾燥密度)にもよるが、測定値が安定するまでに数週間かかる場合もある。さらに、数m程度の大型供試体の場合、試験期間が数年に亘ることもある。   By the way, in the conventional swelling test, since it takes time for the supplied water to uniformly diffuse in the specimen, not only does the measurement take a long time, but if there is not enough time for the measurement, the swelling pressure is set. Sometimes underestimated. Depending on the swelling property of the mineral material and the compressibility (dry density) of the specimen, it may take several weeks for the measured value to stabilize. Furthermore, in the case of a large specimen of about several meters, the test period may be several years.
本発明は、上記実情に鑑みてなされたものであり、供試体寸法に因らず、供試体作製時から水分が均一であり従来と比較して極めて短時間で鉱物材料の膨潤性に関するデータを正確に取得できる膨潤試験法を提供することを目的とする。   The present invention has been made in view of the above circumstances, and regardless of the size of the specimen, the moisture content is uniform from the time of specimen preparation, and data relating to the swelling property of mineral materials in an extremely short time compared to the prior art. An object is to provide a swelling test method that can be obtained accurately.
本発明に係る膨潤試験方法は、鉱物材料を含有する試料と粒状及び/又は粉状の氷とを混合して混合物を調製する混合工程と、混合物を圧縮成形して供試体を得る成形工程と、供試体を測定装置内に封入した状態で供試体に含まれる氷を解凍させて試料の膨潤性に関するデータを取得する測定工程とを備える。   The swelling test method according to the present invention includes a mixing step of preparing a mixture by mixing a sample containing a mineral material and granular and / or powdery ice, and a forming step of compression-molding the mixture to obtain a specimen. And a measurement step of obtaining data relating to the swellability of the sample by thawing ice contained in the test sample in a state in which the test sample is enclosed in the measuring apparatus.
本発明の膨潤試験方法によれば、従来の方法と比較して膨潤挙動が極めて短時間で定常状態となり、測定時間の短縮化が図れる。すなわち、本発明においては、供試体の内部に予め氷を分散させておき、その後、氷を解凍させることにより、供試体の広範囲にわたる水分供給が極めて短期の間に生じる。これに対し、従来の試験方法では、供試体の上面及び下面から給水を行うため、供試体の給水部付近には短時間のうちに水分が供給されるものの、供試体全体には水分が行き渡りにくく、定常状態に至るまでに時間を要する。これに加え、従来の方法は、供試体内部に飽和度の分布が生じやすく、膨潤挙動が複雑で定常状態に至ったか否かの見極めが困難な場合もある。   According to the swelling test method of the present invention, the swelling behavior becomes a steady state in a very short time as compared with the conventional method, and the measurement time can be shortened. That is, in the present invention, by supplying ice in advance within the specimen and then thawing the ice, water supply over a wide range of the specimen occurs in a very short time. In contrast, in the conventional test method, water is supplied from the upper surface and the lower surface of the specimen, so that moisture is supplied in a short time near the water supply portion of the specimen, but moisture is spread throughout the specimen. It is difficult and takes time to reach a steady state. In addition to this, in the conventional method, the distribution of saturation is likely to occur inside the specimen, and the swelling behavior is complicated and it may be difficult to determine whether or not a steady state has been reached.
また、本発明の膨潤試験方法によれば、試料と氷の配合比率を調整することにより、供試体(解凍後)の飽和度を容易に且つ十分に高い精度で調節できる。このため、所望の飽和度におけるデータを取得できる。これに対し、従来の試験方法にあっては、供試体内部にまで水分を浸透させるのに比較的多量の水を給水する必要があり、取得できるデータが一定以上の高い飽和度のものに限定されていた。これに加え、従来の試験方法では、必ずしも供試体の飽和度を正確に把握できないという問題があった。すなわち、従来の試験方法では、試験後に測定装置から取り出した供試体を乾燥させ、乾燥前後の供試体の重量変化から含水比を測定して飽和度を算出していた。測定装置から供試体を取り出すときに減圧が生じ、測定装置の給水路やポーラスメタルの間隙に存在していた水が試料に吸収されてしまい、100%を超える飽和度が算出される場合もあった。   Further, according to the swelling test method of the present invention, the saturation of the specimen (after thawing) can be adjusted easily and with sufficiently high accuracy by adjusting the mixing ratio of the sample and ice. For this reason, data at a desired saturation can be acquired. On the other hand, in the conventional test method, it is necessary to supply a relatively large amount of water in order to allow the water to penetrate into the specimen, and the data that can be acquired is limited to those with high saturation above a certain level. It had been. In addition to this, the conventional test method has a problem that the degree of saturation of the specimen cannot be accurately grasped. That is, in the conventional test method, the specimen taken out from the measuring device after the test was dried, and the water content ratio was measured from the change in weight of the specimen before and after drying to calculate the saturation. When the specimen is taken out from the measuring device, a decompression occurs, and water existing in the water supply channel of the measuring device or the gap between the porous metals is absorbed by the sample, and the saturation degree exceeding 100% may be calculated. It was.
なお、本発明における粒状の氷と粉状の氷との間には明確な境界はなく、「粒状及び/又は粉状の氷」とは、粒径30mm程度以下の氷を意味する。また本発明でいう「飽和度」とは、土粒子、水及び空気からなる三相の土質材料において、間隙の体積(V)に占める水の体積(V)を意味する。
飽和度Sr(%)=V/V×100%
In addition, there is no clear boundary between granular ice and powdered ice in the present invention, and “granular and / or powdered ice” means ice having a particle size of about 30 mm or less. The term “saturation” as used in the present invention means the volume (V W ) of water in the gap volume (V V ) in a three-phase soil material composed of soil particles, water and air.
Saturation degree Sr (%) = V W / V V × 100%
本発明においては、測定工程後における測定装置内の供試体の飽和度が所定の値となるように、混合工程において試料と氷の混合比率を調整することが好ましい。また、試料と氷の混合比率が互いに異なる供試体を複数準備し、当該複数の供試体についてそれぞれ測定工程を実施することが好ましい。所定の飽和度における供試体の膨潤性に関するデータが得られることは、地下構造物を設計するにあたり有用である。   In the present invention, it is preferable to adjust the mixing ratio of the sample and ice in the mixing step so that the degree of saturation of the specimen in the measuring device after the measuring step becomes a predetermined value. In addition, it is preferable to prepare a plurality of specimens having different mixing ratios of the sample and ice and perform the measurement process on each of the plurality of specimens. Obtaining data on the swellability of the specimen at a predetermined degree of saturation is useful in designing underground structures.
混合工程において、試料及び氷の温度を氷点下に保持することが好ましい。これにより、混合工程において氷が解けることを防止でき、試料と氷の混合比率を所望の値に設定しやすい。   In the mixing step, it is preferable to keep the temperature of the sample and ice below the freezing point. Thereby, it is possible to prevent the ice from melting in the mixing step, and it is easy to set the mixing ratio of the sample and ice to a desired value.
成形工程において、供試体の温度を氷点下に保持することが好ましい。これにより、成形工程において氷が解けて試料が膨潤することを防止でき、供試体の飽和度を所望の値に設定しやすい。   In the molding step, it is preferable to keep the temperature of the specimen below the freezing point. Thereby, it can prevent that a sample melt | dissolves in a shaping | molding process and a sample swells, and it is easy to set the saturation of a test body to a desired value.
本発明においては、測定装置内に供試体を封入する作業を行う前に、測定装置を−5℃以下の温度に冷却することが好ましい。測定装置を事前に冷却しておくことで、測定工程よりも前に装置内の氷が解けるのを十分に抑制でき、より精度の高い測定を実施できる。   In the present invention, it is preferable to cool the measuring device to a temperature of −5 ° C. or lower before performing the work of enclosing the specimen in the measuring device. By cooling the measuring apparatus in advance, it is possible to sufficiently suppress melting of ice in the apparatus before the measuring step, and it is possible to perform measurement with higher accuracy.
本発明の膨潤試験方法に供する試料として、ベントナイトを含有するものが挙げられる。   As a sample to be subjected to the swelling test method of the present invention, one containing bentonite can be mentioned.
成形工程において、供試体を平板状に成形することが好ましい。平板状の供試体は、測定装置の収容部の内壁面と接触する部分(供試体の側面)の面積が十分に小さいため、この部分の摩擦力による測定誤差をより小さくできる。   In the molding step, the specimen is preferably molded into a flat plate shape. Since the flat specimen has a sufficiently small area (side surface of the specimen) in contact with the inner wall surface of the accommodating portion of the measuring device, the measurement error due to the frictional force of this part can be further reduced.
本発明によれば、従来と比較して極めて短時間で鉱物材料の膨潤性に関するデータを取得できる。   According to the present invention, it is possible to acquire data relating to the swellability of a mineral material in an extremely short time compared to the prior art.
本発明に係る膨潤試験方法を実施するための測定装置の一例を示す断面図である。It is sectional drawing which shows an example of the measuring apparatus for enforcing the swelling test method which concerns on this invention. 従来の膨潤試験方法を実施するための測定装置の一例を示す断面図である。It is sectional drawing which shows an example of the measuring apparatus for enforcing the conventional swelling test method. 実施例1〜3の膨潤圧試験の結果を示すグラフである。It is a graph which shows the result of the swelling pressure test of Examples 1-3. 比較例1〜6の膨潤圧試験の結果を示すグラフである。It is a graph which shows the result of the swelling pressure test of Comparative Examples 1-6.
以下、図面を参照しつつ本発明の好適な実施形態について説明する。   Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
<測定装置>
図1に示す測定装置10は、鉱物材料を含有する試料の膨潤圧又は膨潤量を測定するためのものであり、供試体S1を封入する収容部5を備える。
<Measurement device>
The measuring apparatus 10 shown in FIG. 1 is for measuring the swelling pressure or the amount of swelling of a sample containing a mineral material, and includes a housing 5 that encloses a specimen S1.
収容部5は、円筒状の試料リング1の内面と、底板2の上面と、載荷ピストン3の下面とによって画成された空間である。試料リング1と底板2はボルト6aによって固定されており、試料リング1の内側に載荷ピストン3が挿入される。試料リング1と当接する底板2の上面及び載荷ピストン3の側面にはOリング7a,7bがそれぞれ装着されており、収容部5から水が漏れないようになっている。収容部5の大きさは、供試体S1のサイズ(例えば、直径60mm、高さ20mm)に応じて適宜設定すればよい。なお、試料リング1は、その上端面にボルト6bによって膨張抑止板8を装着できるようになっている。膨張抑止板8は、測定を開始する前に供試体S1の体積が変位するのを防止するためのものであり、測定の際には外される。   The accommodating portion 5 is a space defined by the inner surface of the cylindrical sample ring 1, the upper surface of the bottom plate 2, and the lower surface of the loading piston 3. The sample ring 1 and the bottom plate 2 are fixed by bolts 6a, and the loading piston 3 is inserted inside the sample ring 1. O-rings 7 a and 7 b are mounted on the upper surface of the bottom plate 2 that contacts the sample ring 1 and the side surface of the loading piston 3, respectively, so that water does not leak from the accommodating portion 5. What is necessary is just to set the magnitude | size of the accommodating part 5 suitably according to the size (for example, diameter 60mm, height 20mm) of specimen S1. In addition, the sample ring 1 can mount | wear with the expansion | swelling suppression board 8 with the volt | bolt 6b at the upper end surface. The expansion suppression plate 8 is for preventing the volume of the specimen S1 from being displaced before starting the measurement, and is removed during the measurement.
供試体S1の膨潤圧を測定する場合は、供試体S1の体積を拘束するため、反力板15aを備えるフレーム15を準備する。載荷ピストン3と反力板15aとの間にロードセル12を配置して膨潤圧を測定する。なお、膨潤量を測定する場合は、ロードセル12や反力板15aを使用する代わりに変位計を使用すればよい。   When measuring the swelling pressure of the specimen S1, a frame 15 including a reaction force plate 15a is prepared in order to restrain the volume of the specimen S1. The load cell 12 is disposed between the loading piston 3 and the reaction force plate 15a to measure the swelling pressure. When measuring the amount of swelling, a displacement meter may be used instead of using the load cell 12 or the reaction force plate 15a.
<膨潤試験方法>
評価対象となり得る鉱物材料としては、ベントナイトに限らず、スメクタイトなどの膨潤性を有する鉱物が挙げられる。ここではベントナイトの膨潤圧を評価対象とする場合を例に挙げる。
<Swelling test method>
Examples of mineral materials that can be evaluated include not only bentonite but also minerals having swelling properties such as smectite. Here, a case where the swelling pressure of bentonite is used as an evaluation target will be described as an example.
例えば、放射性廃棄物処分場を設計するに際し、バリア層の性能を評価する場合には、バリア層の敷設に使用する比較的高純度のベントナイトを採取して試料とする。高性能のバリア層を敷設するには、ベントナイトの含有率(固形分の質量基準)は、95質量%以上であることが好ましく、98質量%以上であることがより好ましい。更には、固形分が実質的にベントナイトのみからなることが最も好ましい。   For example, when designing the radioactive waste disposal site, when evaluating the performance of the barrier layer, relatively high-purity bentonite used for laying the barrier layer is collected and used as a sample. In order to lay a high-performance barrier layer, the bentonite content (based on the mass of the solid content) is preferably 95% by mass or more, and more preferably 98% by mass or more. Furthermore, it is most preferable that the solid content consists essentially of bentonite.
なお、高度な止水性が要求されないバリア層を敷設する場合には、ベントナイトの含有率が低い固形分(ベントナイト含有率:5質量%以上95質量%未満)を使用してもよい。本実施形態に係る試験方法は、ベントナイトの含有率が低い試料の膨潤性も評価することが可能である。試料に含まれるベントナイト以外の固形分としては、砂や土などの土質系材料が挙げられる。   In addition, when laying a barrier layer that does not require high water-stopping properties, a solid content having a low bentonite content (bentonite content: 5% by mass or more and less than 95% by mass) may be used. The test method according to the present embodiment can also evaluate the swellability of a sample having a low bentonite content. Examples of solid content other than bentonite contained in the sample include soil-based materials such as sand and soil.
本実施形態に係る膨潤試験方法は、測定装置10を使用して実施するものであり、混合工程、成形工程及び測定工程をこの順序で備える。   The swelling test method according to the present embodiment is performed using the measuring apparatus 10 and includes a mixing step, a forming step, and a measuring step in this order.
混合工程は、ベントナイトと粒状及び/又は粉状の氷とを混合して混合物を調製する工程である。使用するベントナイト及び氷の粒径は供試体のサイズなどに応じて適宜選択すればよいが、ベントナイトと氷が十分均一に混合した混合物を得る観点から、これらの粒径はなるべく小さいことが好ましい。ベントナイトは粒状及び/又は粉状であることが好ましく、その粒径は好ましくは30mm以下であり、より好ましくは10mm以下である。また、氷の粒径は好ましくは30mm以下であり、より好ましくは20mm以下である。粒状及び/又は粉状の氷は、氷の塊を破砕したり、噴霧した水に液体窒素を吹き付けたり、圧縮水の断熱膨張を利用した降雪機によって作製することができる。   The mixing step is a step of preparing a mixture by mixing bentonite and granular and / or powdered ice. The particle sizes of bentonite and ice to be used may be appropriately selected according to the size of the specimen, but these particle sizes are preferably as small as possible from the viewpoint of obtaining a mixture in which bentonite and ice are sufficiently uniformly mixed. Bentonite is preferably granular and / or powdery, and its particle size is preferably 30 mm or less, more preferably 10 mm or less. The particle size of ice is preferably 30 mm or less, more preferably 20 mm or less. Granular and / or powdery ice can be produced by a snowfall machine that crushes a lump of ice, sprays liquid nitrogen on sprayed water, or uses adiabatic expansion of compressed water.
ベントナイトと氷の混合には、例えば、粉体ミキサーを用いることができ、粉体ミキサーを事前に氷点下(より好ましくは−5℃)に冷却しておくことが好ましい。また混合工程において、試料及び氷の温度を氷点下(より好ましくは−5℃)に保持することが好ましい。これにより、混合工程において氷が解けることを防止でき、試料と氷の混合比率を所望の値に設定しやすい。   For mixing bentonite and ice, for example, a powder mixer can be used, and it is preferable to cool the powder mixer to below the freezing point (more preferably −5 ° C.) in advance. In the mixing step, it is preferable to keep the temperature of the sample and ice below the freezing point (more preferably −5 ° C.). Thereby, it is possible to prevent the ice from melting in the mixing step, and it is easy to set the mixing ratio of the sample and ice to a desired value.
成形工程は、混合工程で得た混合物を圧縮成形して供試体S1を得る工程である。本実施形態においては、測定装置10の収容部5に投入し、載荷ピストン3によって混合物を圧縮することによって供試体S1を得る。混合物の圧縮度合いを調節することによって供試体S1の乾燥密度を調整することができる。なお、乾燥密度γ(g/cm)は、土粒子、水及び空気からなる三相の土質材料の体積をV(cm)とし、土粒子の質量をW(g)としたとき、下記式により算出される値である。
乾燥密度γ=W/V
The molding step is a step of obtaining the specimen S1 by compression molding the mixture obtained in the mixing step. In the present embodiment, the specimen S <b> 1 is obtained by loading the container 5 of the measuring device 10 and compressing the mixture by the loading piston 3. The dry density of the specimen S1 can be adjusted by adjusting the degree of compression of the mixture. The dry density γ D (g / cm 3 ) is obtained when the volume of the three-phase soil material composed of soil particles, water and air is V (cm 3 ), and the mass of the soil particles is W S (g). Is a value calculated by the following equation.
Drying density γ D = W S / V
供試体S1の形状は、試料の物性やデータの用途などに応じて適宜設定することができるが、図1に示すように平板状であることが好ましい。平板状の供試体S1は、試料リング1の内面と接触する部分(供試体S1の側面)の面積が十分に小さいため、この部分の摩擦力による測定誤差をより小さくできる。供試体S1の厚さTと直径Dの比D/Tは、好ましくは3以上である。   The shape of the specimen S1 can be appropriately set according to the physical properties of the sample, the use of data, and the like, but it is preferably a flat plate as shown in FIG. The flat specimen S1 has a sufficiently small area in contact with the inner surface of the sample ring 1 (side surface of the specimen S1), so that the measurement error due to the frictional force of this part can be further reduced. The ratio D / T between the thickness T and the diameter D of the specimen S1 is preferably 3 or more.
測定装置10の収容部5に混合物を投入するに先立ち、測定装置10を氷点下(より好ましくは−5℃以下)に冷却することが好ましい。測定装置10を事前に冷却しておくことで、成形工程において氷が解けるのを十分に抑制できる。また成形工程において、混合物及び供試体S1の温度を氷点下(より好ましくは−5℃)に保持することが好ましい。これにより、成形工程において氷が解けて試料が膨潤することを防止でき、供試体S1の飽和度を所望の値に設定しやすい。   It is preferable to cool the measuring device 10 below the freezing point (more preferably −5 ° C. or lower) prior to charging the mixture into the container 5 of the measuring device 10. By cooling the measuring apparatus 10 in advance, it is possible to sufficiently suppress melting of ice in the molding process. In the molding step, the temperature of the mixture and the specimen S1 is preferably kept below freezing point (more preferably -5 ° C). Thereby, it can prevent that a sample melt | dissolves in a shaping | molding process and a sample swells, and it is easy to set the saturation degree of specimen S1 to a desired value.
測定工程は、供試体S1を収容部5に封入した状態で供試体S1に含まれる氷を解凍させてベントナイトの膨潤性に関するデータを取得する工程である。本実施形態においては、ロードセル12によってベントナイトの膨潤圧のデータを取得する。供試体S1に含まれる氷を解凍するには、測定装置10を常温の環境下に放置してもよいし、あるいは、測定時間の短縮化のため測定装置10に熱を加えてもよい。   The measurement step is a step of obtaining data relating to the swellability of bentonite by thawing the ice contained in the specimen S1 in a state where the specimen S1 is enclosed in the housing part 5. In the present embodiment, data on the swelling pressure of bentonite is acquired by the load cell 12. In order to thaw the ice contained in the specimen S1, the measuring device 10 may be left in a normal temperature environment, or heat may be applied to the measuring device 10 in order to shorten the measuring time.
本実施形態に係る膨潤試験方法によれば、供試体S1の内部には予め氷が分散させられている氷を解凍させることにより、供試体S1の広範囲にわたる水分供給が極めて短期の間に生じる。このため、膨潤挙動が極めて短時間で定常状態となり、測定時間の短縮化が図れる。供試体が数m程度の大型のものであっても水分供給は極めて短期の間に生じ、供試体サイズによらず同様の効果を奏する。   According to the swelling test method according to the present embodiment, the water supply over a wide range of the specimen S1 is generated in a very short time by thawing the ice in which the ice is previously dispersed in the specimen S1. For this reason, the swelling behavior becomes a steady state in a very short time, and the measurement time can be shortened. Even if the specimen is a large one of several meters, the water supply occurs in a very short time, and the same effect can be obtained regardless of the specimen size.
上記試験方法にあっては、試料と氷の配合比率を調整することにより、解凍後の供試体S1の飽和度を容易に且つ十分に高い精度で調節できる。このため、所望の飽和度におけるデータを取得できる。従って、測定工程後における測定装置10内の供試体S1の飽和度が所定の値となるように、混合工程において試料と氷の混合比率を調整してもよいし、あるいは、試料と氷の混合比率が互いに異なる供試体を複数準備し、当該複数の供試体についてそれぞれ測定工程を実施してもよい。所定の飽和度における供試体の膨潤性に関するデータが得られることは、地下構造物を設計するにあたり有用である。   In the test method, the saturation of the specimen S1 after thawing can be adjusted easily and with sufficiently high accuracy by adjusting the mixing ratio of the sample and ice. For this reason, data at a desired saturation can be acquired. Therefore, the mixing ratio of the sample and ice may be adjusted in the mixing step so that the saturation of the specimen S1 in the measuring apparatus 10 after the measuring step becomes a predetermined value, or the mixing of the sample and ice may be performed. A plurality of specimens having different ratios may be prepared, and the measurement process may be performed on each of the plurality of specimens. Obtaining data on the swellability of the specimen at a predetermined degree of saturation is useful in designing underground structures.
以上、本発明の好適な実施形態について説明したが、本発明は上記実施形態に限られない。例えば、上記実施形態においては、成形工程及び測定工程を測定装置10で実施する場合を例示したが、測定装置10とは別の装置を用いて成形工程を実施してもよい。また、上記実施形態においては、取得するデータとして膨潤圧を例示したが、ロードセル12や反力板15aの代わりに変位計を用いて膨潤量のデータを取得してもよい。   As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to the said embodiment. For example, in the said embodiment, although the case where the shaping | molding process and a measurement process were implemented with the measuring apparatus 10 was illustrated, you may implement a shaping | molding process using apparatuses different from the measuring apparatus 10. FIG. Moreover, in the said embodiment, although swelling pressure was illustrated as data to acquire, you may acquire the data of swelling amount using a displacement meter instead of the load cell 12 or the reaction force board 15a.
(実施例1)
図1に示す測定装置10と同様の構成の装置を用いてベントナイトの膨潤圧を測定した。表1に示す通り、測定工程後の飽和度が96.5%となるように、混合工程においてベントナイトと氷の混合比率を調整するとともに成形工程において供試体のサイズ(直径60mm、高さ20mm)を調整した。なお、表1中の「湿潤密度」は土粒子、水及び空気の三相について区別せず、土全体に着目した場合の単体重量を意味し、「含水比」は土粒子の部分の重量(W)に対する水の部分の重量(W)の割合を意味する。
湿潤密度γ(g/cm)=W/V
含水比(%)=W/W
Example 1
The swelling pressure of bentonite was measured using an apparatus having the same configuration as the measuring apparatus 10 shown in FIG. As shown in Table 1, the mixing ratio of bentonite and ice was adjusted in the mixing step so that the saturation after the measuring step was 96.5%, and the size of the specimen (diameter 60 mm, height 20 mm) in the molding step Adjusted. The “wet density” in Table 1 does not distinguish between the three phases of soil particles, water, and air, and means a single unit weight when focusing on the entire soil, and “moisture content” is the weight of the soil particle portion ( It means the ratio of the weight of the water portion (W W ) to W S ).
Wet density γ T (g / cm 3 ) = W / V
Water content (%) = W W / W S
収容部に供試体が封入された状態の測定装置を常温条件下に放置することによって供試体に含まれる氷を解凍させ、その間、ロードセルで膨潤圧を測定した。図3に膨潤圧の経時変化を示す。   The measurement apparatus in a state in which the specimen was sealed in the housing portion was allowed to stand under normal temperature conditions to thaw the ice contained in the specimen, and during that time, the swelling pressure was measured with a load cell. FIG. 3 shows changes with time in the swelling pressure.
(実施例2,3)
測定工程後の供試体の飽和度がそれぞれ90%及び70%となるように供試体を調製したことの他は実施例1と同様にして試験を行った。図3に膨潤圧の経時変化を示す。
(Examples 2 and 3)
The test was performed in the same manner as in Example 1 except that the specimen was prepared so that the saturation of the specimen after the measurement step was 90% and 70%, respectively. FIG. 3 shows changes with time in the swelling pressure.
(比較例1)
従来の測定装置を用いてベントナイトの膨潤圧を測定した。図2に示す従来の測定装置50は、以下の点において図1に示す測定装置10と相違する。
(1)氷が配合されていない試料のみからなる供試体S2が測定対象である点。
(2)供試体S2の上下にポーラスメタルからなるフィルタF1,F2が配置されている点。
(3)供試体S2に水を供給するための給水路52aが底板52に設けられている点。
(4)収容部55から必要に応じて水を排出するための排水路53aが載荷ピストン53に設けられている点。
(Comparative Example 1)
The swelling pressure of bentonite was measured using a conventional measuring device. The conventional measuring apparatus 50 shown in FIG. 2 is different from the measuring apparatus 10 shown in FIG. 1 in the following points.
(1) The point to be measured is a specimen S2 consisting only of a sample containing no ice.
(2) Filters F1 and F2 made of porous metal are arranged above and below the specimen S2.
(3) The water supply path 52a for supplying water to the specimen S2 is provided on the bottom plate 52.
(4) A point where a drainage passage 53a is provided in the loading piston 53 for discharging water from the accommodating portion 55 as necessary.
実施例1と同様の試料(ベントナイト)を収容部に投入した後、載荷ピストンによって試料を圧縮成形し、試料のみからなる供試体(直径60mm、高さ20mm)を得た。給水路から収容部内に水を供給して供試体を膨潤させ、ロードセルで膨潤圧を測定した。図4に膨潤圧の経時変化を示す。測定後、装置から取り出した供試体を乾燥させ、乾燥前後の供試体の重量変化から含水比を測定して飽和度を算出した。表2に結果を示す。   After the same sample (bentonite) as in Example 1 was put into the housing part, the sample was compression molded with a loading piston to obtain a specimen (diameter 60 mm, height 20 mm) consisting only of the sample. Water was supplied from the water supply channel into the accommodating portion to swell the specimen, and the swelling pressure was measured with a load cell. FIG. 4 shows changes with time in the swelling pressure. After the measurement, the specimen taken out from the apparatus was dried, and the water content ratio was measured from the weight change of the specimen before and after drying to calculate the saturation. Table 2 shows the results.
(比較例2〜6)
水の供給量を変更したことの他は比較例1と同様にしてベントナイトの膨潤圧を測定した。表2及び図4に結果を示す。表2に示す通り、比較例3,6においては100%を超える飽和度が算出されるとなった。これは測定装置から供試体を取り出すときに減圧が生じ、測定装置の給水路やポーラスメタルの間隙に存在していた水が試料に吸収されたためと推察される。
(Comparative Examples 2-6)
The swelling pressure of bentonite was measured in the same manner as in Comparative Example 1 except that the amount of water supply was changed. The results are shown in Table 2 and FIG. As shown in Table 2, in Comparative Examples 3 and 6, saturation exceeding 100% was calculated. This is presumably because the pressure was reduced when the specimen was taken out of the measuring device, and the water existing in the water supply channel of the measuring device and the gap between the porous metals was absorbed by the sample.
10…測定装置、50…従来の測定装置、S1…供試体。 DESCRIPTION OF SYMBOLS 10 ... Measuring apparatus, 50 ... Conventional measuring apparatus, S1 ... Specimen.

Claims (8)

  1. 鉱物材料を含有する試料と粒状及び/又は粉状の氷とを混合して混合物を調製する混合工程と、
    前記混合物を圧縮成形して供試体を得る成形工程と、
    前記供試体を測定装置内に封入した状態で前記供試体に含まれる氷を解凍させて前記試料の膨潤性に関するデータを取得する測定工程と、
    を備える膨潤試験方法。
    A mixing step of preparing a mixture by mixing a sample containing a mineral material and granular and / or powdered ice;
    A molding step of compression-molding the mixture to obtain a specimen;
    A measurement step of obtaining data relating to the swellability of the sample by thawing ice contained in the test sample in a state where the test sample is enclosed in a measuring device;
    A swelling test method comprising:
  2. 前記測定工程後における前記測定装置内の前記供試体の飽和度が所定の値となるように、前記混合工程において前記試料と前記氷の混合比率を調整する、請求項1に記載の膨潤試験方法。   The swelling test method according to claim 1, wherein the mixing ratio of the sample and the ice is adjusted in the mixing step so that the saturation degree of the specimen in the measuring device after the measuring step becomes a predetermined value. .
  3. 前記試料と前記氷の混合比率が互いに異なる供試体を複数準備し、当該複数の供試体についてそれぞれ前記測定工程を実施する、請求項1又は2に記載の膨潤試験方法。   The swelling test method according to claim 1 or 2, wherein a plurality of specimens having different mixing ratios of the sample and the ice are prepared, and the measuring step is performed on each of the plurality of specimens.
  4. 前記混合工程において、前記試料及び前記氷の温度を氷点下に保持する、請求項1〜3のいずれか一項に記載の膨潤試験方法。   The swelling test method according to any one of claims 1 to 3, wherein in the mixing step, the temperature of the sample and the ice is kept below freezing point.
  5. 前記成形工程において、前記供試体の温度を氷点下に保持する、請求項1〜4のいずれか一項に記載の膨潤試験方法。   The swelling test method according to any one of claims 1 to 4, wherein, in the molding step, the temperature of the specimen is maintained below freezing point.
  6. 前記測定装置内に前記供試体を封入する作業を行う前に、当該測定装置を−5℃以下の温度に冷却する、請求項1〜5のいずれか一項に記載の膨潤試験方法。   The swelling test method according to any one of claims 1 to 5, wherein the measuring device is cooled to a temperature of -5 ° C or lower before performing the operation of enclosing the specimen in the measuring device.
  7. 前記試料はベントナイトを含有する、請求項1〜6のいずれか一項に記載の膨潤試験方法。   The swelling test method according to any one of claims 1 to 6, wherein the sample contains bentonite.
  8. 前記成形工程において前記供試体を平板状に成形する、請求項1〜7のいずれか一項に記載の膨潤試験方法。   The swelling test method as described in any one of Claims 1-7 which shape | molds the said test body in flat shape in the said formation process.
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