JP6857566B2 - Ground purification method - Google Patents

Description

本発明は、地盤の浄化方法に関する。 The present invention relates to a method for purifying the ground.

下記特許文献１には、難透水層と、難透水層の上下に位置する第１透水層及び第２透水層に亘って形成された汚染部を浄化する浄化方法が示されている。この浄化設備では、汚染部の周囲を３方から取り囲む地下遮断壁を構築し、地下遮断壁で囲まれた部分に、栄養塩供給井戸、揚水井戸を構築している。また、この地下遮断壁、栄養塩供給井戸及び揚水井戸は、第１透水層、難透水層及び第２透水層を貫通して配置されている。 The following Patent Document 1 discloses a purification method for purifying a poorly permeable layer and a contaminated portion formed over the first permeable layer and the second permeable layer located above and below the poorly permeable layer. In this purification facility, an underground barrier that surrounds the contaminated area from three sides is constructed, and a nutrient supply well and a pumping well are constructed in the portion surrounded by the underground barrier. Further, the underground barrier, the nutrient supply well and the pumping well are arranged so as to penetrate the first permeable layer, the impervious permeable layer and the second permeable layer.

特開２００５−１７７６５８号公報Japanese Unexamined Patent Publication No. 2005-177658

上記特許文献１の浄化方法では、第１透水層、第２透水層の双方へ栄養塩を供給し、地下遮断壁で囲まれた領域内全体の微生物を活性化して汚染部の土壌を無害化処理している。この方法では、汚染部だけでなく、上下の複数層、かつ、地下遮断壁で囲まれた領域全体に亘って栄養塩を供給するため、設備が大規模で、必要な栄養塩の量も多い。 In the purification method of Patent Document 1, nutrient salts are supplied to both the first permeable layer and the second permeable layer to activate microorganisms in the entire area surrounded by the underground barrier to detoxify the soil in the contaminated area. Processing. In this method, nutrients are supplied not only to the contaminated area but also to the upper and lower layers and the entire area surrounded by the underground barrier, so the equipment is large and the amount of nutrients required is large. ..

また、難透水層に形成された汚染部、すなわち第１透水層から第２透水層へ汚染物質が浸透する浸透部が細い場合、この浸透部へ栄養塩を行き渡らせることが難しい。 Further, when the contaminated portion formed in the poorly permeable layer, that is, the permeated portion in which the pollutant permeates from the first permeable layer to the second permeable layer is thin, it is difficult to distribute the nutrient salt to this permeated portion.

本発明は、上記事実を考慮して、浸透部の汚染物質を効率的に浄化できる地盤浄化方法を提供することを目的とする。 An object of the present invention is to provide a ground purification method capable of efficiently purifying pollutants in a permeated portion in consideration of the above facts.

請求項１の地盤の浄化方法は、上下方向へ延びる浸透部が存在する低透水層の上面に上部透水層があり、前記低透水層の下面に下部透水層がある地盤の浄化方法であって、前記上部透水層から前記下部透水層に亘って前記浸透部の透水面積を拡げる工程と、前記下部透水層へ浄化剤を注入し、前記上部透水層から前記浄化剤を含んだ地下水を揚水する工程と、を有する。 The method for purifying the ground according to claim 1 is a method for purifying the ground having an upper permeable layer on the upper surface of the low permeable layer having a permeation portion extending in the vertical direction and a lower permeable layer on the lower surface of the low permeable layer. A step of expanding the permeable area of the permeation portion from the upper permeable layer to the lower permeable layer , a purifying agent is injected into the lower permeable layer, and groundwater containing the purifying agent is pumped from the upper permeable layer. It has a process.

上部透水層又は下部透水層に汚染物質があると、この汚染物質は低透水層の浸透部を通って下部透水層又は上部透水層に到達し、また、低透水層の浸透部を汚染する。
そこで請求項１の地盤の浄化方法では、上部透水層から下部透水層に亘って浸透部の透水面積を拡げ、下部透水層から浸透部を介して上部透水層へ、又は、上部透水層から浸透部を介して下部透水層へ、浄化剤を含んだ地下水の流れをつくる。これにより浸透部の汚染物質を浄化できる。 If there is a contaminant in the upper or lower permeable layer, the contaminant will reach the lower permeable layer or upper permeable layer through the permeation of the low permeable layer and will also contaminate the permeation of the low permeable layer.
Therefore, in the method for purifying the ground according to claim 1, the permeable area of the permeation portion is expanded from the upper permeable layer to the lower permeable layer, and the permeation from the lower permeable layer to the upper permeable layer via the permeation portion or from the upper permeable layer. Creates a flow of groundwater containing a purifying agent through the section to the lower permeable layer. This makes it possible to purify the contaminants in the permeation area.

この方法は、浸透部の周囲に地下遮断壁を構築し、地下遮断壁で囲まれた全域を浄化する方法と比較して、浸透部の汚染物質を集中的に浄化できるため浄化の作業効率が高い。
請求項２の地盤の浄化方法は、上下方向へ延びる浸透部が存在する低透水層の上面に上部透水層があり、前記低透水層の下面に下部透水層がある地盤の浄化方法であって、前記上部透水層から前記下部透水層に亘って前記浸透部の透水面積を拡げる工程と、前記上部透水層へ浄化剤を注入し、前記下部透水層から前記浄化剤を含んだ地下水を揚水する工程と、を有する。 Compared to the method of constructing an underground barrier around the permeation part and purifying the entire area surrounded by the underground barrier, this method can intensively purify the pollutants in the permeation part, resulting in more efficient purification work. high.
The method for purifying the ground according to claim 2 is a method for purifying the ground having an upper permeable layer on the upper surface of the low permeable layer having a permeation portion extending in the vertical direction and a lower permeable layer on the lower surface of the low permeable layer. A step of expanding the permeable area of the permeation portion from the upper permeable layer to the lower permeable layer, a purifying agent is injected into the upper permeable layer, and groundwater containing the purifying agent is pumped from the lower permeable layer. It has a process.

請求項３の地盤の浄化方法は、前記低透水層へ注入管を挿入し、前記注入管から前記低透水層へ割裂液を注入して前記浸透部の透水面積を拡げ、前記浸透部へ砂礫を充填する。 The method for purifying the ground according to claim 3 is to insert an injection pipe into the low water permeability layer, inject a split liquid from the injection pipe into the low water permeability layer to expand the water permeability area of the permeation portion, and gravel to the permeation portion. Fill.

請求項３の地盤の浄化方法では、割裂液によって浸透部の透水面積が拡げられる。さらに浸透部に砂礫が充填されるため、透水面積が拡げられた浸透部が土圧によって縮小することを抑制できる。このため、浄化剤を含んだ地下水が浸透部を流れ易い状態を維持できる。 In the method for purifying the ground according to claim 3, the water permeation area of the permeation portion is expanded by the splitting liquid. Further, since the permeation portion is filled with gravel, it is possible to prevent the permeation portion having an expanded water permeation area from shrinking due to earth pressure. Therefore, it is possible to maintain a state in which groundwater containing a purifying agent easily flows through the permeated portion.

請求項４の地盤の浄化方法は、前記低透水層へ前記浸透部を取り囲む管体を挿入する。 In the method for purifying the ground according to claim 4, a pipe body surrounding the permeated portion is inserted into the low permeability layer.

請求項４の地盤の浄化方法によると、浸透部の周囲に管体が挿入される。このため、浸透部を流れる浄化剤を含む地下水が管体の外側へ拡散することが抑制される。これにより浸透部周辺の浄化剤濃度が低くなりにくく、効率的に汚染物質を浄化できる。 According to the method for purifying the ground according to claim 4 , the tubular body is inserted around the infiltration portion. Therefore, the groundwater containing the purifying agent flowing through the permeation portion is suppressed from diffusing to the outside of the pipe body. As a result, the concentration of the purifying agent around the penetrating portion is unlikely to decrease, and pollutants can be efficiently purified.

本発明によると、浸透部の汚染物質を効率的に浄化できる。 According to the present invention, pollutants in the penetrating portion can be efficiently purified.

（Ａ）は本発明の実施形態に係る地盤の浄化方法が適用される地盤において、汚染物質が上部透水層へ拡散した状態を示す立断面図であり、（Ｂ）は汚染物質が低透水層の浸透部へ浸透した状態を示す立断面図である。(A) is a vertical cross-sectional view showing a state in which pollutants are diffused into an upper permeable layer in the ground to which the ground purification method according to the embodiment of the present invention is applied, and (B) is a vertical sectional view showing a state in which pollutants are diffused into a low permeable layer. It is a vertical cross-sectional view which shows the state which permeated into the permeation part of. 本発明の実施形態に係る地盤の浄化方法が適用される地盤において、汚染物質が下部透水層へ拡散した状態を示す立断面図である。FIG. 5 is a vertical cross-sectional view showing a state in which pollutants are diffused into the lower permeable layer in the ground to which the ground purification method according to the embodiment of the present invention is applied. （Ａ）は本発明の実施形態に係る地盤の浄化方法が適用される地盤において、浸透部の位置を特定する方法のうち、下部透水層に注入井戸を構築し、上部透水層に熱電対を埋設した状態を示す立断面図であり、（Ｂ）は注入井戸から下部透水層へ温水を注入した状態を示す立断面図である。In (A), in the ground to which the ground purification method according to the embodiment of the present invention is applied, among the methods for specifying the position of the permeation portion, an injection well is constructed in the lower permeable layer and a thermocouple is provided in the upper permeable layer. It is a vertical sectional view which shows the buried state, and (B) is the vertical sectional view which shows the state which warm water was injected from the injection well into the lower permeable layer. （Ａ）は本発明の実施形態に係る地盤の浄化方法が適用される地盤において、浸透部の位置を特定する方法のうち、下部透水層へ注入した温水によって暖められた地下水が低透水層の浸透部に浸透した状態を示す立断面図であり、（Ｂ）は下部透水層へ注入した温水によって暖められた地下水が上部透水層に到達した状態を示す立断面図である。In (A), in the ground to which the ground purification method according to the embodiment of the present invention is applied, among the methods for specifying the position of the permeation portion, the groundwater warmed by the warm water injected into the lower permeable layer is the low permeable layer. It is a vertical sectional view which shows the state which permeated into a permeation part, and (B) is the vertical sectional view which shows the state which the groundwater warmed by the warm water injected into the lower permeable layer reached the upper permeable layer. （Ａ）は本発明の実施形態に係る地盤の浄化方法において、地盤に浸透部を取り囲むケーシングを設置した状態を示す立断面図であり、（Ｂ）はケーシングの内部にフラクチャリング流体を噴射する注入管を挿入した状態を示す立断面図である。(A) is a vertical sectional view showing a state in which a casing surrounding the permeation portion is installed in the ground in the ground purification method according to the embodiment of the present invention, and (B) is a vertical sectional view showing a state in which a fracturing fluid is injected into the inside of the casing. It is a vertical sectional view which shows the state which inserted the injection tube. （Ａ）は本発明の実施形態に係る地盤の浄化方法において、注入管から高圧の水流を噴射して低透水層に切り込みを形成した状態を示す立断面図であり、（Ｂ）は注入管からフラクチャリング流体を噴射して浸透部を拡張した状態を示す立面図である。(A) is a vertical sectional view showing a state in which a high-pressure water flow is injected from an injection pipe to form a notch in a low permeability layer in the ground purification method according to the embodiment of the present invention, and (B) is an injection pipe. It is an elevation view which shows the state which expanded the permeation part by injecting a fracturing fluid from. 本発明の実施形態に係る地盤の浄化方法において、注入管から砂礫を含むフラクチャリング流体を噴射した状態を示す立断面図である。FIG. 5 is a vertical cross-sectional view showing a state in which a fracturing fluid containing gravel is injected from an injection pipe in the ground purification method according to the embodiment of the present invention. （Ａ）は本発明の実施形態に係る地盤の浄化方法において、地盤からケーシングを引き抜いて注入井戸及び揚水井戸を設置した状態を示す立断面図であり、（Ｂ）は注入井戸から下部透水層へ浄化剤を注入している状態を示す立断面図である。(A) is a vertical sectional view showing a state in which a casing is pulled out from the ground and an injection well and a pumping well are installed in the ground purification method according to the embodiment of the present invention, and (B) is a lower permeable layer from the injection well. It is a vertical sectional view which shows the state which the purifying agent is injected into a well. 本発明の実施形態に係る地盤の浄化方法において、浄化剤が汚染地盤へ浸透した状態を示す立断面図である。FIG. 5 is a vertical cross-sectional view showing a state in which a purifying agent has permeated into contaminated ground in the ground purification method according to the embodiment of the present invention. 本発明の実施形態に係る地盤の浄化方法において、ケーシングを引き抜かない変形例を示した立断面図である。It is a vertical sectional view which showed the modification which did not pull out a casing in the ground purification method which concerns on embodiment of this invention.

（地盤）
本発明の実施形態に係る地盤の浄化方法が適用される地盤Ｇは、図１（Ａ）に示すように、表層地盤である上部透水層Ｇ１と、上部透水層Ｇ１の下面に接する低透水層Ｇ２と、低透水層Ｇ２の下面に接する下部透水層Ｇ３と、を備えている。 (ground)
As shown in FIG. 1A, the ground G to which the ground purification method according to the embodiment of the present invention is applied is an upper permeable layer G1 which is a surface layer ground and a low permeable layer in contact with the lower surface of the upper permeable layer G1. It includes a G2 and a lower permeable layer G3 in contact with the lower surface of the low permeable layer G2.

上部透水層Ｇ１及び下部透水層Ｇ３は砂質土で形成され、地下水が流動可能な帯水層であり、低透水層Ｇ２は粘性土で形成され、地下水が流動し難い遮水層である。なお、低透水層Ｇ２は、上部透水層Ｇ１及び下部透水層Ｇ３より透水性が低い層であればよい。 The upper permeable layer G1 and the lower permeable layer G3 are formed of sandy soil and are an aquifer in which groundwater can flow, and the low permeable layer G2 is formed of cohesive soil and is an impermeable layer in which groundwater is difficult to flow. The low water permeability layer G2 may be a layer having a lower water permeability than the upper water permeability layer G1 and the lower water permeability layer G3.

低透水層Ｇ２には、上下方向へ延びて低透水層Ｇ２の上面から下面まで貫通する浸透部２０が形成されている。浸透部２０は、低透水層Ｇ２に形成された粘性土の亀裂や隙間であり、空洞（土砂が存在しない状態）又は周囲の粘性土より透水性が高い砂質土で形成されており、周囲の粘性土と比較して透水性が高く地下水が流動可能な水路となっている。 The low water permeability layer G2 is formed with a permeation portion 20 extending in the vertical direction and penetrating from the upper surface to the lower surface of the low water permeability layer G2. The permeation portion 20 is a crack or a gap in the cohesive soil formed in the low water permeability layer G2, and is formed of a cavity (in a state where no earth and sand exists) or a sandy soil having a higher water permeability than the surrounding cohesive soil. Compared to the cohesive soil of No. 1, it has a high permeability and is a channel through which groundwater can flow.

浸透部２０は、地下水やガスの噴出孔等自然に形成された物の他、例えば地盤Ｇに建物を建設した際の杭、井戸、地盤調査時のボーリング孔等の跡が残ったものである。なお、図１（Ａ）において符合ＧＬで表される位置は地表面を表しており、符合ＷＬで表される位置は地下水位を表している。 In addition to naturally formed objects such as groundwater and gas ejection holes, the infiltration portion 20 has traces of piles, wells, boring holes, etc. at the time of ground survey, for example, when a building is constructed on the ground G. .. In FIG. 1A, the position represented by the sign GL represents the ground surface, and the position represented by the sign WL represents the groundwater level.

（汚染物質）
このような地盤Ｇにおいて汚染源１０から発生した汚染物質Ｅは、地下水によって流されて上部透水層Ｇ１へ拡散する。また、図１（Ｂ）に示すように低透水層Ｇ２における浸透部２０へ浸透する。さらに、図２に示すように下部透水層Ｇ３へ拡散する。また、低透水層Ｇ２における浸透部２０の周囲の粘性土にも徐々に浸透する。 (Pollutants)
The pollutant E generated from the pollutant source 10 in such a ground G is washed away by groundwater and diffuses into the upper permeable layer G1. Further, as shown in FIG. 1 (B), it permeates into the permeation portion 20 in the low water permeability layer G2. Further, as shown in FIG. 2, it diffuses into the lower permeable layer G3. In addition, it gradually penetrates into the cohesive soil around the permeation portion 20 in the low water permeability layer G2.

このようにして、上部透水層Ｇ１、低透水層Ｇ２における浸透部２０及び下部透水層Ｇ３に亘って汚染物質Ｅが拡散した汚染地盤ＧＥが形成される。 In this way, a contaminated ground GE in which the pollutant E is diffused is formed over the permeation portion 20 in the upper permeable layer G1 and the low permeable layer G2 and the lower permeable layer G3.

（浸透部の位置特定方法）
汚染地盤ＧＥにおいて、上部透水層Ｇ１から下部透水層Ｇ３へ汚染物質Ｅが拡散する経路である浸透部２０を浄化するためには、まず、一例として次の手順で浸透部２０の位置を特定する。 (Method of identifying the position of the penetrating part)
In the contaminated ground GE, in order to purify the permeation portion 20 which is a route for the pollutant E to diffuse from the upper permeation layer G1 to the lower permeation layer G3, first, as an example, the position of the permeation portion 20 is specified by the following procedure. ..

浸透部２０の位置を特定するには、まず図３（Ａ）に示すように、土壌汚染調査等により汚染物質Ｅが検出された部分又はその周囲の部分の任意の場所に、注入井戸３０を構築する。注入井戸３０は、先端部が下部透水層Ｇ３に到達するように構築する。 In order to specify the position of the infiltration portion 20, first, as shown in FIG. 3 (A), the injection well 30 is placed at an arbitrary location in the portion where the pollutant E is detected by the soil contamination survey or the like or the portion around it. To construct. The injection well 30 is constructed so that the tip portion reaches the lower permeable layer G3.

そして、上部透水層Ｇ１に複数の熱電対３２を埋設する。熱電対３２は上部透水層Ｇ１における地下水の温度を検知できる温度センサであり、図３（Ａ）における紙面左右方向の他、紙面前後方向にも複数配置される。それぞれの熱電対３２はリード線３２Ａによって図示しない測定装置へ繋がれており、上部透水層Ｇ１の各地点における温度を測定できる。 Then, a plurality of thermocouples 32 are embedded in the upper permeable layer G1. The thermocouple 32 is a temperature sensor capable of detecting the temperature of the groundwater in the upper permeable layer G1, and a plurality of thermocouples 32 are arranged not only in the left-right direction of the paper surface in FIG. 3A but also in the front-rear direction of the paper surface. Each thermocouple 32 is connected to a measuring device (not shown) by a lead wire 32A, and the temperature at each point of the upper permeable layer G1 can be measured.

次に図３（Ｂ）に示すように、注入井戸３０から下部透水層Ｇ３へ温水を注入する。温水は、下部透水層Ｇ３及び上部透水層Ｇ１の地下水より高温のものを用いる。これにより下部透水層Ｇ３において、注入井戸３０の周囲の地下水が温水と混ざり合い暖められる。一方で、下部透水層Ｇ３の上にある低透水層Ｇ２は下部透水層Ｇ３より透水性が低いため、温水が拡散し難く温められ難い。 Next, as shown in FIG. 3B, hot water is injected from the injection well 30 into the lower permeable layer G3. As the hot water, water having a temperature higher than that of the groundwater in the lower permeable layer G3 and the upper permeable layer G1 is used. As a result, in the lower permeable layer G3, the groundwater around the injection well 30 is mixed with the hot water and warmed. On the other hand, since the low water permeable layer G2 above the lower water permeable layer G3 has a lower water permeability than the lower water permeable layer G3, it is difficult for hot water to diffuse and to be warmed.

なお、図３（Ｂ）において符合Ｈで示した領域は、注入井戸３０から注入された温水と地下水とが混ざり合って暖められた地下水（以下、地下水Ｈと称する。）を示している。 The region indicated by the symbol H in FIG. 3B indicates groundwater (hereinafter referred to as groundwater H) in which hot water injected from the injection well 30 and groundwater are mixed and warmed.

注入井戸３０から下部透水層Ｇ３へ温水の注入を続けると、図４（Ａ）に示すように暖められた地下水Ｈが、浸透部２０の内部へ浸透し、図４（Ｂ）に示すように上部透水層Ｇ１へ拡散する。 When the injection of warm water from the injection well 30 into the lower permeable layer G3 is continued, the warmed groundwater H as shown in FIG. 4 (A) permeates into the inside of the infiltration portion 20, and as shown in FIG. 4 (B). It diffuses into the upper permeable layer G1.

このとき上部透水層Ｇ１においては、浸透部２０から温められた地下水Ｈが拡散するため、熱電対３２が検出する温度は、浸透部２０に近い部分のほうが遠い部分より高い。すなわち、図４（Ｂ）における熱電対３２Ｂ、３２Ｃ、３２Ｄは、浸透部２０までの距離が熱電対３２Ｂ＜３２Ｃ＜３２Ｄであるため、検出される地下水Ｈの温度は熱電対３２Ｂ＞３２Ｃ＞３２Ｄである。 At this time, in the upper permeable layer G1, the groundwater H warmed from the permeation portion 20 diffuses, so that the temperature detected by the thermocouple 32 is higher in the portion near the permeation portion 20 than in the portion far away. That is, in the thermocouples 32B, 32C, and 32D in FIG. 4B, the distance to the penetrating portion 20 is the thermocouple 32B <32C <32D, so that the temperature of the groundwater H detected is the thermocouple 32B> 32C> 32D. Is.

浸透部２０の位置は地上から確認できないが、各熱電対３２で検出される温度はリード線３２Ａでつながれた測定装置で測定できる。このため、最も高い温度を検出した熱電対３２を特定することで、浸透部２０に最も近い熱電対３２を特定することができる。これにより、浸透部２０の位置を特定できる。 Although the position of the penetrating portion 20 cannot be confirmed from the ground, the temperature detected by each thermocouple 32 can be measured by a measuring device connected by a lead wire 32A. Therefore, by specifying the thermocouple 32 that has detected the highest temperature, the thermocouple 32 closest to the penetrating portion 20 can be specified. Thereby, the position of the penetrating portion 20 can be specified.

なお、浸透部２０の位置をより正確に測定するためには、最も高い温度を検出した熱電対３２Ｂの近くに、熱電対３２を追加する。この追加した熱電対３２が指し示す温度によって、より正確な位置を知ることができる。 In order to measure the position of the penetrating portion 20 more accurately, the thermocouple 32 is added near the thermocouple 32B that has detected the highest temperature. A more accurate position can be known from the temperature indicated by the added thermocouple 32.

（地盤の浄化方法）
次に、浸透部２０を浄化する方法について説明する。浸透部２０を浄化するためには、まず図５（Ａ）に示すように、浸透部２０を取り囲むように鋼製のケーシング４０を地盤Ｇへ挿入する。ケーシング４０は先端部が下部透水層Ｇ３に到達するように挿入し、低透水層Ｇ２を貫通させる。 (How to purify the ground)
Next, a method of purifying the penetrating portion 20 will be described. In order to purify the permeation portion 20, first, as shown in FIG. 5A, a steel casing 40 is inserted into the ground G so as to surround the permeation portion 20. The casing 40 is inserted so that the tip portion reaches the lower permeable layer G3 and penetrates the low permeable layer G2.

次に図５（Ｂ）に示すように、ケーシング４０の内部へ注入管４２を挿入する。注入管４２は先端部の管壁に吐出口４２Ａを備えた鋼管であり、吐出口４２Ａが浸透部２０に対向するようにして配置される。 Next, as shown in FIG. 5B, the injection pipe 42 is inserted into the casing 40. The injection pipe 42 is a steel pipe provided with a discharge port 42A on the pipe wall at the tip portion thereof, and is arranged so that the discharge port 42A faces the permeation portion 20.

次に図６（Ａ）に示すように、吐出口４２Ａから浸透部２０に向かって高圧の水流を当てて、吐出口４２Ａと浸透部２０とを連通する切り込み２０Ｊを形成する。この切り込み２０Ｊから浸透部２０へフラクチャリング流体（割裂液）Ｆを圧送し、図６（Ｂ）に示すように浸透部２０を横に拡張して透水面積を拡げる。 Next, as shown in FIG. 6A, a high-pressure water stream is applied from the discharge port 42A toward the permeation portion 20 to form a notch 20J that communicates the discharge port 42A and the permeation portion 20. The fracturing fluid (splitting liquid) F is pumped from the notch 20J to the permeation portion 20, and the permeation portion 20 is laterally expanded to expand the water permeation area as shown in FIG. 6 (B).

フラクチャリング流体Ｆとは、土壌や岩体を水圧で掘削する際に用いられる化学物質が添加された水のことであり、本実施形態においては、自己分解性を有する粘性流体が使用されている。また、汚染物質Ｅの浄化を促進させるため、汚染物質Ｅの分解物質を含有している。なお、自己分解性とは、時間の経過とともに粘性が下がる性質のことであり、この性質によりフラクチャリング流体Ｆは浸透部２０の内部に滞ることなく、後述する揚水井戸４６から回収される。 The fracturing fluid F is water to which a chemical substance used when excavating soil or rock body by water pressure is added, and in this embodiment, a viscous fluid having self-decomposability is used. .. Further, in order to promote the purification of the pollutant E, a decomposing substance of the pollutant E is contained. The autolytic property is a property that the viscosity decreases with the passage of time, and due to this property, the fracturing fluid F is recovered from the pumping well 46 described later without staying inside the permeation portion 20.

さらに図７に示すように、低透水層Ｇ２を形成する粒子よりも粒径が大きい硅砂、砂利や礫（以下、砂礫Ｓと称す）が混ぜられたフラクチャリング流体を吐出口４２Ａから浸透部２０へ吐出して、この砂礫Ｓを浸透部２０に充填する。これにより、透水面積が拡げられた浸透部２０が土圧によって元の状態に戻ることが抑制される。なお、以下の説明において、透水面積が拡げられ砂礫Ｓが充填された浸透部２０を拡張浸透部２０Ｗと称す。 Further, as shown in FIG. 7, a fracturing fluid mixed with silica sand, gravel and gravel (hereinafter referred to as gravel S) having a particle size larger than that of the particles forming the low water permeability layer G2 is discharged from the discharge port 42A through the permeation portion 20. The gravel S is filled in the penetrating portion 20. As a result, it is possible to prevent the permeation portion 20 having an expanded water permeation area from returning to its original state due to earth pressure. In the following description, the permeation portion 20 having an expanded water permeation area and filled with gravel S is referred to as an extended permeation portion 20W.

次に図８（Ａ）に示すように、ケーシング４０及び注入管４２を地盤Ｇから抜きとり、注入井戸４４及び揚水井戸４６を地盤Ｇへ挿入する。注入井戸４４は、抜き取った注入管４２の跡から挿入され、また、先端部が下部透水層Ｇ３に到達するように配置される。揚水井戸４６は、先端部が上部透水層Ｇ１に位置するように配置される。 Next, as shown in FIG. 8A, the casing 40 and the injection pipe 42 are pulled out from the ground G, and the injection well 44 and the pumping well 46 are inserted into the ground G. The injection well 44 is inserted from the trace of the extracted injection pipe 42, and is arranged so that the tip portion reaches the lower permeable layer G3. The pumping well 46 is arranged so that the tip portion is located in the upper permeable layer G1.

低透水層Ｇ２は粘性土で形成されているため、ケーシング４０の引き抜き跡には周囲の土砂（粘土）が流れ込み難く、ケーシング４０の引き抜き跡には粘性土の隙間４０Ｗが形成される。 Since the low permeable layer G2 is formed of cohesive soil, it is difficult for surrounding earth and sand (clay) to flow into the withdrawal traces of the casing 40, and a gap 40W of cohesive soil is formed in the withdrawal traces of the casing 40.

次に図８（Ｂ）に示すように、注入井戸４４から下部透水層Ｇ３へ浄化剤を注入する。また、揚水井戸４６から地下水を引き揚げる。図８（Ｂ）においては、注入井戸４４から注入された浄化剤を含んだ地下水Ｃが、下部透水層Ｇ３へ拡がる様子を示している。このとき地下水Ｃは、拡張浸透部２０Ｗ及び隙間４０Ｗを通って低透水層Ｇ２の内部を、上方へ移動する。 Next, as shown in FIG. 8B, the purifying agent is injected from the injection well 44 into the lower permeable layer G3. In addition, groundwater is withdrawn from the pumping well 46. FIG. 8B shows how the groundwater C containing the purifying agent injected from the injection well 44 spreads to the lower permeable layer G3. At this time, the groundwater C moves upward inside the low permeable layer G2 through the expansion infiltration portion 20W and the gap 40W.

注入井戸４４から浄化剤の注入を続けると、図９に示すように、浄化剤を含んだ地下水Ｃは下部透水層Ｇ３、上部透水層Ｇ１において汚染物質Ｅを覆う範囲まで拡散する。また、拡張浸透部２０Ｗ及び隙間４０Ｗから低透水層Ｇ２の粘性土へ浸透し、汚染物質Ｅを覆う。 When the purification agent is continuously injected from the injection well 44, as shown in FIG. 9, the groundwater C containing the purification agent diffuses to the range covering the pollutant E in the lower permeable layer G3 and the upper permeable layer G1. Further, it permeates into the cohesive soil of the low permeability layer G2 from the extended permeation portion 20W and the gap 40W, and covers the pollutant E.

なお、浄化剤を含んだ地下水Ｃが汚染物質Ｅを覆う範囲まで拡散及び浸透する前に揚水井戸４６から揚水されないように、浄化剤は所定期間注入後、汚染地盤ＧＥへ拡散及び浸透させる漬け置き期間を確保してから再び注入を開始する。このように断続的に浄化剤を注入することで、使用する浄化剤の量を合理化し、汚染物質Ｅを徐々に浄化する。 The purifying agent is soaked in the contaminated ground GE after being injected for a predetermined period so that the groundwater C containing the purifying agent is not pumped from the pumping well 46 before it is diffused and permeated to the extent that it covers the pollutant E. After securing the period, start the injection again. By injecting the purifying agent intermittently in this way, the amount of the purifying agent used is rationalized, and the pollutant E is gradually purified.

以上の工程により、浸透部２０（拡張浸透部２０Ｗ）、浸透部２０の周囲の低透水層Ｇ２、上部透水層Ｇ１及び下部透水層Ｇ３の汚染物質Ｅが浄化される。 By the above steps, the pollutants E of the permeation section 20 (extended permeation section 20W), the low water permeation layer G2 around the permeation section 20, the upper water permeation layer G1 and the lower water permeation layer G3 are purified.

（作用・効果）
本実施形態に係る地盤の浄化方法によると、下部透水層Ｇ３から拡張浸透部２０Ｗ及び隙間４０Ｗを介して上部透水層Ｇ１へ浄化剤を含んだ地下水Ｃの流れをつくる。これにより浸透部２０及び浸透部２０の周囲の低透水層Ｇ２の汚染物質Ｅを浄化できる。 (Action / effect)
According to the ground purification method according to the present embodiment, a flow of groundwater C containing a purifying agent is created from the lower permeable layer G3 to the upper permeable layer G1 via the extended permeable portion 20W and the gap 40W. As a result, the pollutant E in the permeation portion 20 and the low water permeation layer G2 around the permeation portion 20 can be purified.

この方法は、例えば浸透部２０、上部透水層Ｇ１及び下部透水層Ｇ３の汚染物質Ｅを含む部分の周囲に地下遮断壁を構築し、地下遮断壁で囲まれた全域を浄化する方法と比較して、浸透部２０の汚染物質を集中的に浄化できるため浄化の作業効率が高い。また、例えば浸透部２０の周囲の地盤を掘削して、汚染物質Ｅを含んだ粘性土ごと除去する方法と比較して、粘性土を除去しなくてもよいので工事が軽微である。 This method is compared with, for example, a method of constructing an underground barrier around the portion of the permeation portion 20, the upper permeable layer G1 and the lower permeable layer G3 containing the pollutant E, and purifying the entire area surrounded by the underground barrier. Therefore, the pollutants in the penetrating portion 20 can be intensively purified, so that the purification work efficiency is high. Further, as compared with the method of excavating the ground around the infiltration portion 20, for example, and removing the cohesive soil containing the pollutant E, the cohesive soil does not have to be removed, so that the construction work is light.

また、本実施形態においては、浸透部２０の周囲をケーシング４０で囲んだ状態で浸透部２０を拡張している。このため注入管４２から浸透部２０へ圧送されたフラクチャリング流体Ｆは、横方向に向かって低透水層Ｇ２を開削することが難しく、浸透部２０の内部を縦方向へ流れる。この水流によって浸透部２０の壁が浸食されることにより、浸透部２０の流路面積が拡張される。 Further, in the present embodiment, the permeation portion 20 is expanded in a state where the permeation portion 20 is surrounded by the casing 40. Therefore, it is difficult for the fracturing fluid F pumped from the injection pipe 42 to the permeation portion 20 to open the low water permeability layer G2 in the lateral direction, and the fracturing fluid F flows in the inside of the permeation portion 20 in the vertical direction. The wall of the penetrating portion 20 is eroded by this water flow, so that the flow path area of the penetrating portion 20 is expanded.

なお、本実施形態においては、拡張浸透部２０Ｗの形成後ケーシング４０を引き抜いているが、本発明の実施形態はこれに限らず、図１０に示すように、ケーシング５０を残置した状態で浄化剤を注入してもよい。このようにすることで、拡張浸透部２０Ｗを流れる浄化剤を含んだ地下水Ｃが、ケーシング５０の外側へ浸透することが抑制される。これにより、拡張浸透部２０Ｗの周辺の浄化剤濃度が低くなりにくく、効率的に浸透部２０（拡張浸透部２０Ｗ）及び浸透部２０の周囲の低透水層Ｇ２の汚染物質Ｅを浄化できる。 In the present embodiment, the casing 40 is pulled out after the expansion penetration portion 20W is formed, but the embodiment of the present invention is not limited to this, and as shown in FIG. 10, the purifying agent is left in the casing 50. May be injected. By doing so, the groundwater C containing the purifying agent flowing through the expanded permeation portion 20W is suppressed from permeating to the outside of the casing 50. As a result, the concentration of the purifying agent around the expanded permeation portion 20W is unlikely to decrease, and the pollutant E in the permeation portion 20 (expanded permeation portion 20W) and the low water permeation layer G2 around the permeation portion 20 can be efficiently purified.

なお、ケーシング５０を残置した状態で浄化剤を注入する場合、低透水層Ｇ２の透水係数や汚染物質Ｅの発生時期などから、浸透部２０の周囲において汚染物質Ｅが浸透している範囲を推測し、その推測範囲を取り囲むことができる直径を備えたケーシング５０を用いることが好ましい。 When the purifying agent is injected with the casing 50 left, the range in which the pollutant E permeates around the permeation portion 20 is estimated from the water permeability coefficient of the low water permeability layer G2 and the generation time of the pollutant E. However, it is preferable to use a casing 50 having a diameter capable of surrounding the estimated range.

また、浸透部２０の浄化時にケーシング５０を残置する場合でも、浸透部２０及び浸透部２０の周囲の低透水層Ｇ２の汚染物質Ｅを浄化した後は、ケーシング５０を引き抜き、上部透水層Ｇ１におけるケーシング５０の外側部分の汚染物質Ｅ１を浄化する。汚染物質Ｅ１の浄化にあたっては、注入井戸４４の先端を上部透水層Ｇ１まで引き上げて、上部透水層Ｇ１へ浄化剤を注入することが好ましい。 Further, even when the casing 50 is left when purifying the permeation portion 20, after purifying the pollutant E of the low water permeation layer G2 around the permeation portion 20 and the permeation portion 20, the casing 50 is pulled out to form the upper water permeation layer G1. Purify the contaminant E1 on the outer portion of the casing 50. In purifying the pollutant E1, it is preferable to pull up the tip of the injection well 44 to the upper permeable layer G1 and inject the purifying agent into the upper permeable layer G1.

さらに上部透水層Ｇ１へ浄化剤を注入する場合で、かつ、下部透水層Ｇ３における汚染物質Ｅの浄化が完了している場合においては、拡張浸透部２０Ｗ及びケーシング５０の跡には改良材を充填し、地下水の流れを遮断するとよい。これにより上部透水層Ｇ１へ注入した浄化剤が拡張浸透部２０Ｗ及びケーシング５０の跡を通って下部透水層Ｇ３へ流失することを抑制できる。 Further, when the purifying agent is injected into the upper permeable layer G1 and the purification of the pollutant E in the lower permeable layer G3 is completed, the traces of the expanded permeation portion 20W and the casing 50 are filled with an improving material. However, it is advisable to block the flow of groundwater. As a result, it is possible to prevent the purifying agent injected into the upper permeable layer G1 from flowing out to the lower permeable layer G3 through the traces of the expanded permeation portion 20W and the casing 50.

また、本実施形態においては図６（Ａ）、（Ｂ）に示すように、浸透部２０における透水面積を拡げるために注入管４２及びフラクチャリング流体Ｆを用いているが、本発明の実施形態はこれに限らない。例えば地上から浸透部２０の真上又は真上の近傍から地盤Ｇを掘削して、低透水層Ｇ２を上下に貫通する透水孔を形成してもよい。浄化剤を含んだ地下水Ｃがこの透水孔を流れることで、浸透部２０及び浸透部２０の周囲の低透水層Ｇ２の汚染物質Ｅを浄化できる。 Further, in the present embodiment, as shown in FIGS. 6A and 6B, the injection pipe 42 and the fracturing fluid F are used in order to increase the water permeation area in the permeation portion 20, but the embodiment of the present invention is used. Is not limited to this. For example, the ground G may be excavated from the ground directly above or in the vicinity of the infiltration portion 20 to form a water permeable hole that penetrates the low water permeable layer G2 up and down. By allowing the groundwater C containing the purifying agent to flow through the water permeation holes, the pollutant E of the permeation portion 20 and the low permeation layer G2 around the permeation portion 20 can be purified.

また、本実施形態においては図８（Ａ）、（Ｂ）に示すように下部透水層Ｇ３へ注入井戸４４を挿入し、上部透水層Ｇ１へ揚水井戸４６を挿入しているが本発明の実施形態はこれに限らない。すなわち、下部透水層Ｇ３へ揚水井戸４６を挿入し、上部透水層Ｇ１へ注入井戸４４を挿入してもよい。この場合、注入井戸４４から上部透水層Ｇ１へ注入された浄化剤を含んだ地下水Ｃは、重力によって、拡張浸透部２０Ｗ及び隙間４０Ｗを流れて下部透水層Ｇ３へ到達しやすい。これにより揚水井戸４６を駆動させるポンプの出力を小さくできる。 Further, in the present embodiment, as shown in FIGS. 8A and 8B, the injection well 44 is inserted into the lower permeable layer G3, and the pumping well 46 is inserted into the upper permeable layer G1. The form is not limited to this. That is, the pumping well 46 may be inserted into the lower permeable layer G3, and the injection well 44 may be inserted into the upper permeable layer G1. In this case, the groundwater C containing the purifying agent injected from the injection well 44 into the upper permeable layer G1 easily reaches the lower permeable layer G3 by flowing through the expanded permeation portion 20W and the gap 40W due to gravity. As a result, the output of the pump that drives the pumping well 46 can be reduced.

また、本実施形態において注入井戸４４は注入管４２の跡から挿入しているが、本発明の実施形態はこれに限らず、例えばケーシング４０の跡である隙間４０Ｗの外側から挿入してもよい。さらに、注入井戸４４の本数は１本に限らず、複数設置してもよい。揚水井戸４６についてもその場所や本数は任意に設定することができる。このように、本発明の実施形態は様々な態様で実施できる。 Further, in the present embodiment, the injection well 44 is inserted from the trace of the injection pipe 42, but the embodiment of the present invention is not limited to this, and may be inserted from the outside of the gap 40W which is the trace of the casing 40, for example. .. Further, the number of injection wells 44 is not limited to one, and a plurality of injection wells may be installed. The location and number of pumping wells 46 can be arbitrarily set. As described above, the embodiments of the present invention can be implemented in various aspects.

２０ 浸透部
Ｆ フラクチャリング流体（割裂液）
Ｇ 地盤
Ｇ１ 上部透水層
Ｇ２ 低透水層
Ｇ３ 下部透水層
３２ 熱電対（温度センサ）
Ｃ 浄化剤を含んだ地下水
Ｓ 砂礫
４０、５０ ケーシング（管体） 20 Penetration part F Fracturing fluid (split liquid)
G Ground G1 Upper permeable layer G2 Low permeable layer G3 Lower permeable layer 32 Thermocouple (temperature sensor)
C Groundwater containing purifying agent S Gravel 40, 50 Casing (tube)

Claims (4)

上下方向へ延びる浸透部が存在する低透水層の上面に上部透水層があり、前記低透水層の下面に下部透水層がある地盤の浄化方法であって、
前記上部透水層から前記下部透水層に亘って前記浸透部の透水面積を拡げる工程と、
前記下部透水層へ浄化剤を注入し、前記上部透水層から前記浄化剤を含んだ地下水を揚水する工程と、
を有する地盤の浄化方法。 This is a method for purifying the ground with an upper permeable layer on the upper surface of the low permeable layer having a permeation portion extending in the vertical direction and a lower permeable layer on the lower surface of the low permeable layer.
A step of expanding the water permeable area of the permeation portion from the upper water permeable layer to the lower water permeable layer, and
A step of injecting a purifying agent into the lower permeable layer and pumping groundwater containing the purifying agent from the upper permeable layer.
How to purify the ground with. 上下方向へ延びる浸透部が存在する低透水層の上面に上部透水層があり、前記低透水層の下面に下部透水層がある地盤の浄化方法であって、
前記上部透水層から前記下部透水層に亘って前記浸透部の透水面積を拡げる工程と、
前記上部透水層へ浄化剤を注入し、前記下部透水層から前記浄化剤を含んだ地下水を揚水する工程と、
を有する地盤の浄化方法。 This is a method for purifying the ground with an upper permeable layer on the upper surface of the low permeable layer having a permeation portion extending in the vertical direction and a lower permeable layer on the lower surface of the low permeable layer.
A step of expanding the water permeable area of the permeation portion from the upper water permeable layer to the lower water permeable layer, and
A step of injecting a purifying agent into the upper permeable layer and pumping groundwater containing the purifying agent from the lower permeable layer.
How to purify the ground with. 前記低透水層へ注入管を挿入し、前記注入管から前記低透水層へ割裂液を注入して前記浸透部の透水面積を拡げ、前記浸透部へ砂礫を充填する、請求項１又は２に記載の地盤の浄化方法。 According to claim 1 or 2 , an injection pipe is inserted into the low water permeability layer, and a split liquid is injected from the injection pipe into the low water permeability layer to expand the water permeability area of the permeation portion and fill the permeation portion with gravel. The described ground purification method. 前記低透水層へ前記浸透部を取り囲む管体を挿入する、請求項１〜３の何れか1項に記載の地盤の浄化方法。 The method for purifying the ground according to any one of claims 1 to 3, wherein a pipe body surrounding the permeation portion is inserted into the low water permeability layer.

Images