JP6171420B2 - Method of construction of retaining wall - Google Patents
Method of construction of retaining wall Download PDFInfo
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- JP6171420B2 JP6171420B2 JP2013047188A JP2013047188A JP6171420B2 JP 6171420 B2 JP6171420 B2 JP 6171420B2 JP 2013047188 A JP2013047188 A JP 2013047188A JP 2013047188 A JP2013047188 A JP 2013047188A JP 6171420 B2 JP6171420 B2 JP 6171420B2
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本発明は、土留壁を、汚染土壌を含む帯水層、その下方の不透水層を通過して、さらにその下方の帯水層に達するように施工する方法に関する。 The present invention relates to a method for constructing a retaining wall so as to pass through an aquifer containing contaminated soil and an impermeable layer below the aquifer and further reach the aquifer below the aquifer.
杭を、汚染土壌を含む帯水層、その下方の不透水層を通過して、さらにその下方の帯水層に達するように施工する方法として、ケーシングを、汚染土壌を含む帯水層を通過して不透水層に達するように設置してその内側の汚染土壌を不透水材に置換してから、杭をケーシングの内側に打設する方法が知られている（例えば、非特許文献１参照）。当該方法によれば、杭の打設に伴う不透水層の下方の帯水層への汚染物質の漏出を防止することができる。 Pass the casing through the aquifer containing the contaminated soil as a method of constructing the pile so that it passes through the aquifer containing the contaminated soil and the impermeable layer below it, and reaches the aquifer below it. Then, after installing the impermeable layer to replace the contaminated soil inside the impermeable layer, a method of driving a pile inside the casing is known (for example, see Non-Patent Document 1). ). According to this method, it is possible to prevent leakage of contaminants to the aquifer below the impermeable layer due to the driving of the pile.
土留壁を、汚染土壌を含む帯水層、その下方の不透水層を通過して、さらにその下方の帯水層に達するように施工する場合には、杭の打設に用いる上述の方法のようにケーシングを使用することができないことから、別の方法によって、不透水層の下方の帯水層への汚染物質の漏出を防止する必要がある。 When constructing the retaining wall so that it passes through the aquifer containing contaminated soil and the impermeable layer below it, and reaches the aquifer below it, Thus, it is necessary to prevent leakage of contaminants to the aquifer below the impermeable layer by another method.
本発明は、上記事情に鑑みてなされたものであり、掘削領域を囲む土留壁を、汚染土壌を含む第一帯水層、その下方の不透水層を通過して、さらにその下方の第二帯水層に達するように施工するにあたり、第二帯水層への汚染物質の漏出を防止することを課題にするものである。 The present invention has been made in view of the above circumstances, and passes through the retaining wall surrounding the excavation region through the first aquifer containing contaminated soil and the impermeable layer below the first aquifer and further below the second aquifer. In constructing to reach the aquifer, it is an object to prevent leakage of contaminants to the second aquifer.
上記課題を解決するために、本発明に係る土留壁の施工方法は、掘削領域を囲む土留壁を、汚染土壌を含む第一帯水層、及び、その下方の不透水層を通過して、さらにその下方の第二帯水層に達するように施工する方法であって、前記第一帯水層の前記汚染土壌を横断し、前記土留壁の打ち込み予定線を挟むようにして一対の仮設土留め壁を構築し、該仮説土留め壁で挟まれた領域内を掘削して前記汚染土壌を除去してから遮水性を有する壁状部を構築する工程と、前記土留壁を、前記壁状部、及び、前記不透水層を通過して、前記第二帯水層に達するように施工する工程と、を備え、前記壁状部は、前記土留壁の打ち込み予定線を挟んで、掘削領域側の厚みが非掘削領域側の厚みより小さく設定される。 In order to solve the above problems, the method of constructing a retaining wall according to the present invention passes through the retaining wall surrounding the excavation region, the first aquifer containing contaminated soil, and the impermeable layer below it. Furthermore, it is a method of constructing so as to reach the second aquifer below it, a pair of temporary earth retaining walls across the contaminated soil of the first aquifer and sandwiching the planned line of the retaining wall constructs and a step of constructing a wall-shaped portion having a water barrier after removing the contaminated soil by excavating sandwiched by the hypothesis soil retaining wall area, the earth retaining wall, the wall-shaped portion, And a process of passing through the impermeable layer and reaching the second aquifer, and the wall-like portion is located on the side of the excavation region across the planned line of the earth retaining wall. The thickness is set smaller than the thickness on the non-excavation region side .
前記土留壁の施工方法において、前記壁状部を構築する工程は、前記壁状部を構築する工程は、埋め戻し材で前記一対の仮設土留壁の間を埋め戻し、前記壁状部を構築する工程とを備え、前記一対の仮設土留壁と前記埋め戻し材との少なくとも一方が遮水性を有する。
In construction methods of the earth retaining wall, the step of constructing the wall-like portion, the step of constructing the wall-like section, to return in backfill material filling between the pair of temporary earth retaining wall, the wall-shaped portion and a step of constructing, at least one of impermeability of the backfill material and the pair of temporary earth retaining wall.
前記土留壁の施工方法において、前記一対の仮設土留壁は、前記掘削領域に設ける第一仮設土留壁と、前記掘削領域の外側に設ける第二仮設土留壁とであり、前記埋め戻し材は、不透水材であってもよく、前記第二仮設土留壁と前記土留壁との間において前記不透水材による遮水性が確保されるように、前記第二仮設土留壁と前記土留壁との距離が設定されていてもよい。また、前記第一仮設土留壁は遮水性を有してもよく、該第一仮設土留壁は、前記掘削領域を掘削して前記汚染土壌を除去するまで残置してもよい。 In the construction method of the retaining wall, the pair of temporary retaining walls is a first temporary retaining wall provided in the excavation area and a second temporary retaining wall provided outside the excavation area, and the backfill material is A water impermeable material may be used, and the distance between the second temporary earth retaining wall and the earth retaining wall so as to ensure water shielding by the impermeable material between the second temporary earth retaining wall and the earth retaining wall. May be set. In addition, the first temporary retaining wall may have water shielding properties, and the first temporary retaining wall may be left until the contaminated soil is removed by excavating the excavation area.
本発明によれば、掘削領域を囲む土留壁を、汚染土壌を含む第一帯水層、その下方の不透水層を通過して、さらにその下方の第二帯水層に達するように施工するにあたり、第二帯水層への汚染物質の漏出を防止することができる。 According to the present invention, the retaining wall surrounding the excavation region is constructed so as to pass through the first aquifer containing contaminated soil and the impermeable layer below the first aquifer and further reach the second aquifer below it. In this case, it is possible to prevent leakage of contaminants into the second aquifer.
以下、本発明の一実施形態を、図面を参照しながら説明する。図１は、本発明の一実施形態に係る方法を用いて施工した土留壁１を示す立面図である。この図に示すように、土留壁１が施工された地盤は、汚染土壌（基準不適合土壌）６を含む第一帯水層２と、その下方に位置する第一不透水層（準不透水層を含む）３と、その下方に位置する第二帯水層４と、その下方に位置する第二不透水層（準不透水層を含む）５とを備えている。汚染土壌６は、土留壁１に囲まれた掘削領域７とその外側の非掘削領域８とに跨るように存在している。 Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an elevation view showing a retaining wall 1 constructed using a method according to an embodiment of the present invention. As shown in this figure, the ground on which the retaining wall 1 is constructed includes a first aquifer 2 including contaminated soil (reference nonconforming soil) 6 and a first impermeable layer (semi-impermeable layer) located below the first aquifer. 3), a second aquifer 4 positioned below, and a second impermeable layer (including a semi-impermeable layer) 5 positioned therebelow. The contaminated soil 6 exists so as to straddle the excavation area 7 surrounded by the retaining wall 1 and the non-excavation area 8 outside the excavation area 7.
土留壁１は、鋼矢板壁であり、第一帯水層２、第一不透水層３、及び第二帯水層４を貫通して第二不透水層５に達するように構築されている。ここで、図２の平面図にも示すように、第一帯水層２には、汚染土壌６を横断するように不透水材からなる壁状体１０が構築され、土留壁１の一部は、壁状体１０を縦断するように（壁厚方向に二分するように）構築されている。壁状体１０は、第一帯水層２の下端から上端までの高さを有しており、土留壁１と汚染土壌６との間を全高、全幅に亘って隔てて地下水の移動を遮断している。 The retaining wall 1 is a steel sheet pile wall, and is constructed so as to penetrate the first aquifer 2, the first impermeable layer 3, and the second aquifer 4 to reach the second impermeable layer 5. . Here, as shown also in the plan view of FIG. 2, a wall-like body 10 made of a water-impermeable material is constructed in the first aquifer 2 so as to cross the contaminated soil 6, and a part of the retaining wall 1. Is constructed so as to cut through the wall-like body 10 (dividing into two in the wall thickness direction). The wall-like body 10 has a height from the lower end to the upper end of the first aquifer 2 and blocks the movement of groundwater by separating the retaining wall 1 and the contaminated soil 6 across the entire height and width. doing.
ここで、壁状体１０の土留壁１を挟んだ両側の部位の厚みは、不透水材の品質を考慮したうえで、当該部位が、上述のガイドラインで規定された不透水層（厚さが５ｍ以上であり、かつ、透水係数が毎秒１００ナノメートル（１．０×１０ｍ−７／秒）以下の地層）と同等以上の遮水の効力を有するように設定されている。なお、不透水材としては、ソイルモルタルとベントナイトとの混合物等が挙げられる。 Here, in consideration of the quality of the water-impermeable material, the thickness of the portions on both sides of the wall-shaped body 10 across the retaining wall 1 is the impermeable layer (thickness is determined by the above-mentioned guidelines). It is set to have a water shielding effect equivalent to or higher than 5 m and a water permeability of 100 nanometers per second (a stratum of 1.0 × 10 m −7 / second) or less. Examples of the water-impermeable material include a mixture of soil mortar and bentonite.
図３〜図７は、土留壁１の施工手順を示す立面図又は平面図である。まず、図３及び図４に示すように、仮設土留壁１１、１２を、汚染土壌６を横断し、土留壁１の打ち込み予定線９を挟んで対向するように平行に構築し、仮設土留壁１１、１２の幅方向両端を連結する仮設土留壁１３、１４を構築する。仮設土留壁１１〜１４は、遮水壁である鋼矢板壁であり、第一帯水層２を貫通して第一不透水層３に達するように構築する。次に、図５に示すように、第一帯水層２の仮設土留壁１１〜１４で囲まれた領域を掘削する。この際、仮設土留壁１１〜１４内の汚染土壌６を除去する。なお、この掘削工を山留めをせずに実施できる程に第一帯水層２が浅い場合には、仮設土留壁１１〜１４を構築する工程を省略してもよい。 3 to 7 are elevational views or plan views showing the construction procedure of the retaining wall 1. First, as shown in FIG. 3 and FIG. 4, the temporary retaining walls 11, 12 are constructed in parallel so as to cross the contaminated soil 6 and face each other across the planned driving line 9 of the retaining wall 1. Temporary earth retaining walls 13 and 14 that connect both ends in the width direction of 11 and 12 are constructed. The temporary earth retaining walls 11 to 14 are steel sheet pile walls that are impermeable walls, and are constructed so as to penetrate the first aquifer 2 and reach the first impermeable layer 3. Next, as shown in FIG. 5, the area | region enclosed by the temporary earth retaining walls 11-14 of the 1st aquifer 2 is excavated. At this time, the contaminated soil 6 in the temporary earth retaining walls 11 to 14 is removed. In addition, when the 1st aquifer 2 is shallow enough to be able to implement this excavation without attaching a mountain, the process of constructing temporary earth retaining walls 11 to 14 may be omitted.
次に、図６に示すように、仮設土留壁１１〜１４内を不透水材で埋め戻すことにより、仮設土留壁１１〜１４内に、不透水性（遮水性）の壁状体１０を構築する。次に、図７に示すように、仮設土留壁１１〜１４を除去する。その後、土留壁１を、掘削領域７を囲い、第一帯水層２、第一不透水層３、及び第二帯水層４を貫通して第二不透水層５に達するように構築する（図１参照）。この際、土留壁１の一部を、壁状体１０を縦断し、第一帯水層２の壁状体１０、第一不透水層３、及び第二帯水層４を貫通して第二不透水層５に達するように構築する。その後、掘削領域７を掘削する際に、掘削領域７内の汚染土壌６と不透水材とを除去する。 Next, as shown in FIG. 6, the impervious (water-impervious) wall-like body 10 is constructed in the temporary earth retaining walls 11 to 14 by backfilling the temporary earth retaining walls 11 to 14 with an impermeable material. To do. Next, as shown in FIG. 7, the temporary earth retaining walls 11 to 14 are removed. Thereafter, the retaining wall 1 is constructed so as to surround the excavation region 7 and penetrate the first aquifer 2, the first impermeable layer 3, and the second aquifer 4 to reach the second impermeable layer 5. (See FIG. 1). At this time, a part of the retaining wall 1 passes through the wall 10 and passes through the wall 10 of the first aquifer 2, the first impermeable layer 3, and the second aquifer 4. It is constructed so as to reach the two impermeable layers 5. Then, when excavating the excavation area 7, the contaminated soil 6 and the impermeable material in the excavation area 7 are removed.
以上説明したように、本実施形態に係る土留壁１の施工方法では、まず、第一帯水層２の汚染土壌６と土留壁１の施工領域とが含まれる領域を掘削して遮水性を有する壁状体１０を構築し、つぎに、土留壁１を、壁状体１０、第一不透水層３を通過して、第二帯水層４に達するように施工し、その後、土留壁１で囲まれた掘削領域７を掘削して汚染土壌を除去する。これによって、土留壁１を、汚染土壌６を含む第一帯水層２、その下方の第一不透水層３を通過して、さらにその下方の第二帯水層４に達するように施工するにあたり、第一帯水層２内において、壁状体１０によって、施工中の土留壁１と汚染土壌６との間が全高、全幅に亘って遮水されるため、第一帯水層２から第二帯水層４への汚染物質の漏出を防止することができる。 As explained above, in the construction method of the retaining wall 1 according to the present embodiment, first, a region including the contaminated soil 6 of the first aquifer 2 and the construction region of the retaining wall 1 is excavated to perform water shielding. The retaining wall 10 is constructed, and then the retaining wall 1 is constructed so as to pass through the retaining body 10 and the first impermeable layer 3 and reach the second aquifer 4, and then the retaining wall. The excavated area 7 surrounded by 1 is excavated to remove the contaminated soil. Thus, the retaining wall 1 is constructed so as to pass through the first aquifer 2 including the contaminated soil 6 and the first impermeable layer 3 below the first aquifer 2 and reach the second aquifer 4 below it. In the first aquifer 2, since the wall 10 blocks the wall between the retaining wall 1 under construction and the contaminated soil 6 over the entire height and width, the first aquifer 2 Leakage of contaminants to the second aquifer 4 can be prevented.
また、壁状体１０を構築する工程では、第一帯水層２の汚染土壌６と土留壁１の施工領域とが含まれる領域に、一対の遮水壁である仮設土留壁１１、１２を土留壁１を挟むように施工し、一対の仮設土留壁１１、１２の間を掘削して汚染土壌６を除去し、不透水材で一対の仮設土留壁１１、１２の間を埋め戻す。これによって、土留壁１と汚染土壌６との間を全高、全幅に亘って遮水する壁状体１０を構築することができる。 Moreover, in the process of constructing the wall-like body 10, temporary earth retaining walls 11 and 12, which are a pair of impermeable walls, are provided in an area including the contaminated soil 6 of the first aquifer 2 and the construction area of the earth retaining wall 1. Construction is performed so that the retaining wall 1 is sandwiched, and the contaminated soil 6 is removed by excavating between the pair of temporary retaining walls 11 and 12, and the space between the pair of temporary retaining walls 11 and 12 is backfilled with an impermeable material. Thereby, it is possible to construct the wall-like body 10 that shields water between the retaining wall 1 and the contaminated soil 6 over the entire height and width.
なお、一対の仮設土留壁１１、１２と埋め戻し材との双方が遮水性を有することは必須ではない。例えば、本実施形態のように、土留壁１と仮設土留壁１１、１２との間の埋め戻し材が遮水性を有する場合には、仮設土留壁１１、１２が遮水性を有することは必須ではない。また、内側の仮設土留壁１１を掘削領域７を掘削するまでの間、残置する場合には、土留壁１と内側の仮設土留壁１１との間の埋め戻し材は、土砂や土嚢等の透水性を有するものでもよい。さらに、外側の仮設土留壁１２を掘削領域７を掘削した後も残置する場合には、土留壁１と外側の仮設土留壁１２との間の埋め戻し材は、土砂や土嚢等の透水性を有するものでもよい。 In addition, it is not essential that both of the pair of temporary earth retaining walls 11 and 12 and the backfilling material have water shielding properties. For example, when the backfill material between the retaining wall 1 and the temporary retaining walls 11 and 12 has a water-impervious property as in this embodiment, it is essential that the temporary retaining walls 11 and 12 have a water-impervious property. Absent. When the inner temporary retaining wall 11 is left until the excavation area 7 is excavated, the backfill material between the retaining wall 1 and the inner temporary retaining wall 11 is water permeable such as earth and sand or sandbags. It may have a property. Furthermore, when the outer temporary retaining wall 12 is left after the excavation area 7 is excavated, the backfill material between the retaining wall 1 and the outer temporary retaining wall 12 is permeable to soil and sand. You may have.
図８は、他の実施形態に係る方法を用いて施工した土留壁１を示す概略図である。この図に示すように、本実施形態では、第一帯水層２には、汚染土壌６を横断するように不透水材からなる壁状体２０が構築され、土留壁１の一部は、壁状体２０を縦断するように構築されている。壁状体２０は、第一帯水層２の下端から上端までの高さを有している。 FIG. 8 is a schematic view showing a retaining wall 1 constructed using a method according to another embodiment. As shown in this figure, in this embodiment, in the first aquifer 2, a wall-like body 20 made of an impermeable material is constructed so as to cross the contaminated soil 6, and a part of the retaining wall 1 is It is constructed so as to cut the wall-like body 20 vertically. The wall-like body 20 has a height from the lower end to the upper end of the first aquifer 2.
ところで、壁状体２０は、土留壁１を境にして厚みＴ１の非掘削領域８側と厚みＴ２（＜Ｔ１）の掘削領域７側とに二分されている。また、非掘削領域８側の仮設土留壁１２は除去されているのに対して、掘削領域７側の仮設土留壁１１は掘削領域７の掘削工の前まで残置されている。 By the way, the wall-like body 20 is divided in two into the non-excavation region 8 side having a thickness T1 and the excavation region 7 side having a thickness T2 (<T1) with the retaining wall 1 as a boundary. Further, the temporary retaining wall 12 on the non-excavation area 8 side is removed, while the temporary retaining wall 11 on the excavation area 7 side is left until the excavation in the excavation area 7.
ここで、壁状体２０の非掘削領域８側の厚みＴ１は、不透水層の品質を考慮したうえで、当該部位が、上述のガイドラインで規定された不透水層（厚さが５ｍ以上であり、かつ、透水係数が毎秒１００ナノメートル（１．０×１０ｍ−７／秒）以下の地層）と同等以上の遮水の効力を有するように設定されている。それに対して、壁状体２０の掘削領域７側の厚みＴ２は、非掘削領域８側の厚みＴ１よりも小さく設定されており、壁状体２０の掘削領域７側は、非掘削領域８側に比して遮水の効力が小さい。しかし、遮水壁である仮設土留壁１１が、土留壁１の掘削領域７側において土留壁１と汚染土壌６との間を遮水している。 Here, the thickness T1 on the non-excavation region 8 side of the wall-shaped body 20 is the impermeable layer (thickness is 5 m or more) defined by the above-mentioned guidelines after considering the quality of the impermeable layer. In addition, the water permeability is set to have a water shielding effect equivalent to or higher than 100 nanometers per second (a stratum of 1.0 × 10 m −7 / second) or less. On the other hand, the thickness T2 on the excavation area 7 side of the wall-like body 20 is set smaller than the thickness T1 on the non-excavation area 8 side, and the excavation area 7 side of the wall-like body 20 is on the non-excavation area 8 side. Compared to, water shielding effectiveness is small. However, the temporary earth retaining wall 11, which is a water shielding wall, shields between the earth retaining wall 1 and the contaminated soil 6 on the excavation region 7 side of the earth retaining wall 1.
図９〜図１２は、本実施形態に係る土留壁１の施工手順を示す概略図である。まず、図９に示すように、仮設土留壁１１、１２を、汚染土壌６を横断し、土留壁１の打ち込み予定線９を挟んで対向するように平行に構築し、仮設土留壁１１、１２の幅方向両端を連結する仮設土留壁１３、１４（図示省略）を構築する。仮設土留壁１１〜１４は、第一帯水層２を貫通して第一不透水層３に達するように構築する。 9-12 is the schematic which shows the construction procedure of the retaining wall 1 which concerns on this embodiment. First, as shown in FIG. 9, the temporary retaining walls 11, 12 are constructed in parallel so as to cross the contaminated soil 6 and face each other across the planned driving line 9 of the retaining wall 1. Temporary earth retaining walls 13 and 14 (not shown) that connect both ends in the width direction are constructed. The temporary earth retaining walls 11 to 14 are constructed so as to penetrate the first aquifer 2 and reach the first impermeable layer 3.
ここで、仮設土留壁１１、１２の間隔は、上述の実施形態に比して狭く設定する。そして、非掘削領域８側の仮設土留壁１２と打ち込み予定線９との間隔Ｌ１は、後に構築される壁状体２０の非掘削領域８側の厚みＴ１が上述の厚みを満足するように設定する。また、掘削領域７側の仮設土留壁１１と打ち込み予定線９との間隔Ｌ２は、間隔Ｌ１よりも小さくなるように設定する。 Here, the space | interval of the temporary earth retaining walls 11 and 12 is set narrowly compared with the above-mentioned embodiment. The distance L1 between the temporary retaining wall 12 on the non-excavation region 8 side and the planned driving line 9 is set so that the thickness T1 on the non-excavation region 8 side of the wall-like body 20 to be constructed later satisfies the above-described thickness. To do. The interval L2 between the temporary earth retaining wall 11 on the excavation region 7 side and the planned driving line 9 is set to be smaller than the interval L1.
次に、図１０に示すように、第一帯水層２の仮設土留壁１１〜１４で囲まれた領域を掘削して、仮設土留壁１１〜１４の汚染土壌６を除去する。次に、図１１に示すように、仮設土留壁１１〜１４内を不透水材で埋め戻すことにより、仮設土留壁１１〜１４内に、不透水性の壁状体２０を構築する。次に、図１２に示すように、非掘削領域８側の仮設土留壁１２、及び仮設土留壁１３、１４を除去し、掘削領域７側の仮設土留壁１１は残置する。 Next, as shown in FIG. 10, the area | region enclosed by the temporary earth retaining walls 11-14 of the 1st aquifer 2 is excavated, and the contaminated soil 6 of the temporary earth retaining walls 11-14 is removed. Next, as shown in FIG. 11, the impervious wall-like body 20 is constructed in the temporary earth retaining walls 11 to 14 by backfilling the temporary earth retaining walls 11 to 14 with a water-impermeable material. Next, as shown in FIG. 12, the temporary earth retaining wall 12 on the non-excavation area 8 side and the temporary earth retaining walls 13 and 14 are removed, and the temporary earth retaining wall 11 on the excavation area 7 side is left.
次に、土留壁１を、掘削領域７を囲い、第一帯水層２、第一不透水層３、及び第二帯水層４を貫通して第二不透水層５に達するように構築する（図８参照）。この際、土留壁１の一部を、壁状体２０を縦断し、第一帯水層２の壁状体２０、第一不透水層３、及び第二帯水層４を貫通して第二不透水層５に達するように構築する。そして、掘削領域７を掘削し、その際、掘削領域７内の汚染土壌６を除去する。その後、仮設土留壁１１と掘削領域７内の不透水材とを除去する。 Next, the retaining wall 1 is constructed so as to surround the excavation region 7 and penetrate the first aquifer 2, the first impermeable layer 3, and the second aquifer 4 to reach the second impermeable layer 5. (See FIG. 8). At this time, a part of the retaining wall 1 passes through the wall-like body 20 and passes through the wall-like body 20 of the first aquifer 2, the first impermeable layer 3, and the second aquifer 4. It is constructed so as to reach the two impermeable layers 5. And the excavation area | region 7 is excavated and the contaminated soil 6 in the excavation area | region 7 is removed in that case. Thereafter, the temporary earth retaining wall 11 and the impermeable material in the excavation area 7 are removed.
以上説明したように、本実施形態に係る土留壁１の施工方法では、土留壁１とその外側の仮設土留壁１２との間の距離Ｌ１が、不透水材による遮水性が確保されるように設定されている。これによって、掘削領域７を掘削した後に外側の遮水壁たる仮設土留壁１２を撤去する場合でも、土留壁１の外側の不透水材によって、非掘削領域８に残る汚染土壌６と土留壁１との間を全高、全幅に亘って遮水することができる。 As explained above, in the construction method of the retaining wall 1 according to the present embodiment, the distance L1 between the retaining wall 1 and the temporary retaining wall 12 outside the retaining wall 1 is ensured to be water impermeable by the impermeable material. Is set. As a result, even when the temporary retaining wall 12 as the outer impermeable wall is removed after excavating the excavation area 7, the contaminated soil 6 and the retaining wall 1 remaining in the non-excavated area 8 by the impermeable material outside the retaining wall 1. Can be shielded over the entire height and width.
ここで、掘削領域７に存在する汚染土壌６は、掘削領域７を掘削する際に除去するため、土留壁１の内側では、それまでの間だけ遮水できればよい。そこで、本実施形態に係る土留壁１の施工方法では、内側の仮設土留壁１１を、掘削領域７を掘削して汚染土壌６を除去するまで残置し、土留壁１と内側の仮設土留壁１１との間の距離を、遮水性の確保を目的とせずに短く設定している。これによって、壁状体２０の厚みを小さくすることができ、不透水材の使用量や地盤の掘削量を低減することができる。 Here, since the contaminated soil 6 present in the excavation area 7 is removed when excavating the excavation area 7, it is only necessary to block the water inside the retaining wall 1 until then. Therefore, in the construction method of the retaining wall 1 according to the present embodiment, the inner temporary retaining wall 11 is left until the contaminated soil 6 is removed by excavating the excavation region 7, and the inner retaining wall 11 and the inner temporary retaining wall 11. The distance between is set to be short without aiming to ensure water shielding. Thereby, the thickness of the wall-shaped body 20 can be made small, and the usage-amount of a water-impermeable material and the excavation amount of a ground can be reduced.
なお、上述の実施形態は、本発明の理解を容易にするためのものであり、本発明を限定するものではない。本発明はその趣旨を逸脱することなく、変更、改良され得ると共に本発明にはその等価物が含まれることは勿論である。例えば、上述の実施形態では、土留壁を鋼矢板壁としたが、鋼管矢板壁やソイルセメント柱列壁等の他の土留壁にしてもよい。 In addition, the above-mentioned embodiment is for making an understanding of this invention easy, and does not limit this invention. It goes without saying that the present invention can be changed and improved without departing from the gist thereof, and that the present invention includes equivalents thereof. For example, in the above-described embodiment, the retaining wall is a steel sheet pile wall, but another retaining wall such as a steel pipe sheet pile wall or a soil cement column wall may be used.
１ 土留壁、２ 第一帯水層、３ 第一不透水層、４ 第二帯水層、５ 第二不透水層、６ 汚染土壌、７ 掘削領域、８ 非掘削領域、９ 打ち込み予定線、１０ 壁状体、１１、１２、１３、１４ 仮設土留壁、２０ 壁状体 1 retaining wall, 2 first aquifer, 3 first impermeable layer, 4 second aquifer, 5 second impermeable layer, 6 contaminated soil, 7 excavated area, 8 non-excavated area, 9 planned implantation line, 10 Wall-shaped body, 11, 12, 13, 14 Temporary earth retaining wall, 20 Wall-shaped body
Claims (4)
前記第一帯水層の前記汚染土壌を横断し、前記土留壁の打ち込み予定線を挟むようにして一対の仮設土留め壁を構築し、該仮説土留め壁で挟まれた領域内を掘削して前記汚染土壌を除去してから遮水性を有する壁状部を構築する工程と、
前記土留壁を、前記壁状部、及び、前記不透水層を通過して、前記第二帯水層に達するように施工する工程と、を備え、
前記壁状部は、前記土留壁の打ち込み予定線を挟んで、掘削領域側の厚みが非掘削領域側の厚みより小さく設定されることを特徴とする土留壁の施工方法。 A method of constructing a retaining wall surrounding an excavation area so as to pass through a first aquifer containing contaminated soil and an impermeable layer below the first aquifer and further reach a second aquifer below it. ,
Across said contaminated soil of the first aquifer, the earth retaining so as to sandwich the driving schedule line of the wall to construct a pair of temporary earth retaining wall, said drilling sandwiched by the hypothesis soil retaining wall region A step of constructing a wall-like portion having a water barrier after removing the contaminated soil;
Constructing the retaining wall so as to pass through the wall-like portion and the impermeable layer and reach the second aquifer,
The method for constructing a retaining wall, wherein the wall-shaped portion is set such that a thickness on an excavation region side is smaller than a thickness on a non-excavation region side across a planned driving line of the retaining wall.
前記一対の仮設土留壁と前記埋め戻し材との少なくとも一方が遮水性を有することを特徴とする請求項１に記載の土留壁の施工方法。 The step of constructing the wall-like section, to return in backfill material filling between the pair of temporary earth retaining wall, and a step of constructing the wall-shaped portion,
The construction method of the retaining wall according to claim 1, wherein at least one of the pair of temporary retaining walls and the backfilling material has a water shielding property.
前記埋め戻し材は、不透水材であり、
前記第二仮設土留壁と前記土留壁との間において前記不透水材による遮水性が確保されるように、前記第二仮設土留壁と前記土留壁との距離が設定されていることを特徴とする請求項２に記載の土留壁の施工方法。 The pair of temporary retaining walls is a first temporary retaining wall provided in the excavation area and a second temporary retaining wall provided outside the excavation area,
The backfill material is an impermeable material,
And wherein the aqueous barrier by the impermeable material so as to secure a distance between the second temporary earth retaining wall and the earth retaining wall is set between said second temporary earth retaining wall and the earth retaining wall earth retaining wall the method of construction according to claim 2.
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