JP4293435B2 - Construction method of managed revetment - Google Patents

Description

  In the present invention, when a landfill section is constructed by installing a ready-made structure such as a caisson on the seabed ground and constructing a landfill section, the seabed ground and the structure and the seabed ground are shielded. The present invention relates to a construction method of a management-type revetment that makes it possible to demonstrate the water quality well.

In order to reclaim waste in the sea, when building a revetment that partitions the landfill and surrounds it, a foundation mound is built on the surface of the seabed, and rubble is piled up to a specified height. An off-the-shelf structure such as caisson is installed on the foundation mound. Then, wastes are dumped on the inner water surface surrounded by the revetment, landfilled with a predetermined thickness on the surface after landfill, new land is created, and new demand for parks, etc. Can be used.
In addition, in landfills partitioned by the revetment, it is necessary to use means for preventing water from flowing in and out of the revetment. For this reason, the surface of the foundation mound and the submarine ground inside the revetment is impermeable. Means such as laying sheets and water-impervious mats without gaps and water-insulating joints (connections) between caissons are used (for example, see Patent Document 1).
JP 2001-152425 A

  However, when applying a water-impervious treatment method that lays out conventional water-impervious sheets and water-impervious mats and blocks the flow of water to and from the revetment, In many cases, processing cannot be performed so that no gap is generated at both ends of the caisson side and the seabed side. In particular, in recent years, there are many cases of securing landfill disposal sites for sea areas with a water depth of 10 m or more. In such deep water areas, water shielding sheets such as laying water shielding sheets without gaps are often used. Many problems also appear in the construction work. When caisson is installed on the foundation mound as a revetment main work, the partition revetment is passed between the stones of the foundation mound or through a water-permeable stratum such as sand or silt on the seabed where the caisson is installed. It is inevitable that water will circulate between the inside and outside. In addition, even when the seabed ground is well sealed, water shielding between the bottom surface of the caisson and the foundation mound and between the layer where the seabed ground is sealed and the foundation mound It may be incomplete, and problems such as water leaking from landfills leaking out to the open ocean are likely to occur.

  Furthermore, in addition to the case where the submarine ground is a soil having a small water permeability, even in the case of a rock having a small permeability, water may circulate between the lower surface of the caisson and the rock, such a construction site. There are still many problems that need to be solved in the water-impervious treatment.

  The present invention can effectively perform water shielding treatment at the management-type waste landfill revetment of the waste sea surface disposal site, and the partition revetment, the foundation mound, and the bottom seabed as a highly reliable water shielding portion. It aims to provide a way to build.

The present invention relates to a method for constructing a partition revetment that is constructed so as to surround a portion of a predetermined area in a sea area and is partitioned for dumping waste.
In the present invention, the ground for constructing the partition revetment is subjected to the construction of impermeable ground, which is impermeable ground, and the construction of providing a groove at a predetermined depth and width,
Arranging structures like caisson in a row in the groove part, constructing a partition revetment as a section for dumping waste, and constructing a water shielding treatment at each connection part of the structure,
In the groove, a layer of a water shielding material is constructed at a predetermined height and width across the lower surface of the base of the structure and the side of the structure,
A water-impervious treatment is performed by a water-impervious material constructed between both the impermeable improved ground and the structure and the joint between the structures.

  As mentioned above, when constructing a partition revetment by installing a caisson-like structure, work on improving the impervious ground to make the permeability coefficient of the submarine ground as a supporting foundation a small value. Water shielding can be achieved by providing a layer of a water shielding material between the lower part of the material and the impermeable ground improving part or the like serving as the support base. And by filling a fluidity impermeable material between the caisson lower part and the impermeable ground improvement part as the structure, a water impermeable treatment is performed by constructing a water impermeable layer that does not generate a gap. Can be easily performed, and the reliability of the partition revetment can be improved. In addition, even when the seabed ground for constructing the revetment is a rock with a small hydraulic conductivity, it is only necessary to construct a layer of water shielding material with a predetermined thickness between the base of the caisson to be installed and the seabed ground, It can exhibit good water barrier properties. Furthermore, according to the geology of the ground at the place where the revetment is installed, any means can be used to construct a water-impervious mixture layer having a predetermined height in the lower part of the caisson, etc. It becomes possible to easily perform the water shielding treatment on the base.

  The construction method of the management type revetment will be described according to the example shown in the figure. As shown in Fig. 1, a general management-type waste landfill revetment is a ground improvement that has been constructed to improve the ground in a predetermined area where the load of the revetment built on the submarine ground 1 acts. The marine structure 10 is constructed by constructing the part 4 and installing a ready-made structure such as caisson on the ground improvement part 4. However, the geology of the ground for constructing the offshore structure 10 is often a sedimentary layer 3 having a high hydraulic conductivity, such as a sand layer, rather than a rock having a strong and low hydraulic conductivity.

  Therefore, when constructing the offshore structure 10 by the caisson 11 or the like on the sedimentary layer 3, as shown in the drawing, ground improvement work is performed over a predetermined width including the construction area of the structure 10. The impermeable ground improvement part 4 is constructed. As the ground improvement section 4, as is generally done conventionally, an improvement work that reduces the hydraulic conductivity by mixing a hardener such as cement with the soil of the sedimentary layer 3 and hardening the soil. Install. In addition, when constructing the ground improvement portion 4, it is necessary to provide the excavation groove portion 5 that later removes the soil and positions the base portion of the caisson 11 in the lower portion where the caisson 11 is installed. The hardened material is not mixed in the portion corresponding to the excavation groove 5.

  Further, when the ground improvement portion 4 is constructed, when the ground is soft ground such as sedimentary soil, etc., a water shielding structure in which piles that exhibit a number of water shielding properties are continuously placed on the ground. It is also possible to construct a wall. When constructing a pile wall that exhibits water-imperviousness, a pile-like structure that can exhibit impermeability by driving a casing vertically into the ground and dropping and hardening sand mixed with asphalt or cement, etc. A method of building is also proposed. And the said water-impervious pile can be made to adjoin, and it can construct | assemble in a line shape, and can construct the wall-shaped impermeable wall which has predetermined | prescribed thickness.

  Of course, the depth at which the ground improvement portion 4 is constructed desirably reaches the bedrock 2 as an impermeable layer, and any depth corresponding to the thickness of the caisson 11 installed on the upper portion. Is constructed so that the water in the sea area inside and outside partitioned by the marine structure 10 does not flow through the seabed ground. After installing the ground improvement part 4, in order to install the caisson 11, the soil of the untreated part not mixed with the water shielding material of the ground improvement part 4 is removed to construct the excavation groove part 5, and the excavation groove part A foundation stone layer 6 is constructed by laying a stone or the like on the surface of the groove 5 with a predetermined thickness. Then, after leveling the surface of the foundation stone layer 6, a water shielding layer of a water shielding material or an asphalt mixture is applied to cover the voids of the foundation stone and the surface of the foundation stone layer, and a water shielding treatment is performed. After that, the caisson 11 is installed, the water shielding treatment is performed between the adjacent caissons 11, and the water shielding sheet 15 or the like is laid to perform the water shielding, thereby ensuring double water shielding.

  As a water barrier for the lower part of the caisson 11, it is constructed by placing an asphalt mixture having a high fluidity in the inside of the excavation groove 5, and asphalt having a high fluidity by heating from both sides of the excavation groove 5. The mixture can also be poured. And since the fluidity | liquidity of the mixture is large, the said fluid enters also into the clearance gap between the foundation stone layers 6, and it is filled so that a clearance gap does not remain also between the stones which form the foundation stone layer 6. FIG. If the width of the caisson is large and the asphalt mixture is not sufficiently filled just by pouring from the side of the foundation, the asphalt mixture is applied to the foundation stone layer as described above. Water shielding treatment can be performed.

  In addition, underwater concrete is placed in place of the foundation stone layer, asphalt mats are laid, asphalt mixture is cast to a predetermined thickness, and a water barrier layer is provided to construct a caisson A construction method or the like may be used. Moreover, since the asphalt mixture layer 20 is filled between the ground wall and the caisson, the inside of the excavated groove has water impermeability together with the ground improvement portion 4 which has been subjected to ground improvement to reduce the water permeability coefficient. The asphalt mixture layer 20 is combined so that the water barrier at the lower part of the caisson can be exhibited well.

  In the example shown in FIG. 1, the asphalt mixture layer 20 is filled in the excavation groove portion 5 and a water shielding work between the caissons 11 is performed. The lower part of the water sheet 15 is extended on the asphalt mixture layer 20 by a predetermined length, the pressing layer 16 is constructed on the ground, and an asphalt block 16a is further formed at the end of the water shielding sheet 15 by a predetermined size. The tip of the water-impervious sheet is held. The pressing layer 16 and the end block 16a can be constructed by laying an asphalt mat having an arbitrary thickness or by placing an asphalt mixture, so that water is formed in the lower part of the water shielding sheet 15. Make sure there are no gaps. Moreover, although the edge part block 7 and the embankment layer 8 are provided in the sea side of the offshore structure 10 as a guide member at the time of installing a caisson, such an auxiliary means is not necessarily required.

  The caisson 11 for constructing the offshore structure 10 is constructed by arranging a plurality of things having a predetermined height, thickness and length, and constructing a partition around the landfill. The ready-made structure described as the caisson is a concrete block-like structure, or a so-called hybrid caisson in which the surface of the main body made of steel or steel is coated with a predetermined thickness. Or what was manufactured in arbitrary sizes, such as a cell, can be used as a structure. Moreover, the joint water-impervious treatment part 12 for water-blocking between the caisson 11 (between joints) can use the construction method conventionally used as shown in FIG.

  As the joint water-impervious treatment portion 12 shown in FIGS. 2 and 3, a seal member 13 configured in a substantially cylindrical shape with rubber or the like is disposed between the caissons 11 and 11 at a predetermined interval. , 13a is filled with an asphalt mixture to construct an asphalt packed bed 14. Further, an arbitrary formwork is disposed outside the seal member 13a to construct a layer 14a of a solidified material such as concrete. In addition, the inside of the sealing members 13 and 13a is also filled with asphalt mixture, sand, or the like as necessary so that the sealing member 13 is not crushed. In addition to using such a method, it is also possible to apply a conventionally known joint impervious work.

  On the ground (surface) inside the groove where the structure is to be installed, a mat having a water-impervious property is laid without constructing the foundation stone layer, or asphalt mixture and underwater concrete with a predetermined thickness. It is also possible to construct a water-impervious body that can exhibit water-imperviousness and perform a process of imparting water-imperviousness between the impermeable ground and the water-impervious body. And after installing a caisson on the said water-impervious body, an asphalt mixture is laid to cover the base of the caisson, and a water-impervious treatment is performed between the structure and the water-impervious (impermeable) ground. It is also possible.

  The embodiment described in FIG. 1 is an example in which the seabed 1 is on the rock 2 as the impermeable layer and the sedimentary layer 3 as the sedimentary layer is present as a sand or silt layer. . On the other hand, the offshore structure 10 may be constructed by installing the caisson 11 or the like directly on the rock mass 2 having a very strong and low hydraulic conductivity. The examples shown in FIGS. 4 and 5 illustrate a water-impervious work between the ground and the lower part of the caisson when the caisson 11 is installed on the rock bed 2 that is strong and has a small water permeability. As shown in FIG. 4, when the rock mass 2 can be excavated relatively easily, the excavation groove portion 5 a having a predetermined depth and width with respect to the rock mass 2 is constructed using an arbitrary excavation means. And after constructing the foundation stone layer 6 by the predetermined thickness on the bottom face of the said excavation groove part 5a, the caisson 11 is mounted on it and the asphalt mixture is filled into the clearance gap (space part) inside the excavation groove part 5a. Then, after the asphalt mixture layer 20 is constructed, the joint water-impervious treatment portions are respectively constructed between the adjacent caissons 11.

  In addition, as shown in FIG. 4, when it is difficult to excavate and construct a groove in the rock, as shown in FIG. 5, on both sides of the part where the caisson 11 is installed (on both sides of the inner and outer sea areas) It is possible to arrange end blocks 21 and 21a having a predetermined height and width and to fill the asphalt mixture between the end blocks. The asphalt mixture layer 20 is constructed at the same height as the end block 21 so that the base of the caisson 11 is buried to a predetermined height. The end block can be easily constructed on the rock mass 2 by using a construction method such as placing underwater concrete while assembling the formwork. In addition, the end block 21 can be constructed by transporting a relatively large concrete block constructed on land and transporting it by a trolley and sinking it in a predetermined sea area.

  As described above, the end block 21 and the caisson 11 are formed by applying the asphalt mixture layer 20 between the end blocks 21 and 21a so as to cover both side surfaces and the lower surface of the base of the caisson 11. It can be integrated through the asphalt mixture layer 20. And, when the base of the caisson is firmly supported by the asphalt mixture, even when a wave impact is applied to the revetment, the caisson and the end block are integrated in the offshore structure. The effect of retaining the can be exhibited well.

4 and 5, when the caisson is installed on the strong rock mass 2, the surface of the rock mass 2 is not flat. A method of installing the caisson 11 can be used after the stone layer 6 is constructed and the surface thereof is leveled substantially flat.
Therefore, even when the asphalt mixture is constructed after the foundation stone layer is constructed in the lower part of the caisson, the highly fluid asphalt mixture also enters between the stones of the foundation stone layer 6, and the surface of the bedrock 2 and the caisson 11 can also exhibit good water barrier properties. Alternatively, a method may be used in which the asphalt mixture is applied to the bedrock to a predetermined thickness, and then the caisson or the end block is placed, and then the asphalt mixture layer 20 is applied in the groove.

When constructing the offshore structure as described above, the water permeability in the sedimentary layer 3 is improved, caisson is installed in the excavation groove 5, and the joint water-impermeable treatment part between the caisson and the asphalt mixture layer under the caisson. It is assumed that the strength of the offshore structure is not sufficient only by constructing 20. As shown in FIG. 6, when the strength of the ground is not sufficient for the pressure of the waste buried in the partition revetment and the pressure of the waves, an auxiliary strengthening means is added as shown in FIG. May be provided.
When constructing the auxiliary strengthening means, for example, on one side of the caisson 11, a steel sheet pile (steel sheet pile, steel pipe sheet pile, steel box sheet pile, steel H-type sheet pile, etc. are collectively named) The pile wall 25 is constructed in a row and connected to the caisson using a connecting tool 26 such as a tie rod. And the well-known water shielding process is performed with respect to each connection part of the steel sheet piles which comprise the said pile wall 25, and a perpendicular | vertical water shielding wall is constructed | assembled. Further, by constructing a filler layer 27 having a small water permeability coefficient in the space between the pile wall 25 and the caisson 11, it is possible to further enhance the water shielding performance and to combine with the caisson. Thus, the water shielding property can be maintained better.

  As the filling material 27, it is possible to use a material having a property that a harmful material does not dissolve in water and flows out, such as a building waste material. For example, a material that does not corrode such as concrete debris is used. And good. In addition, the soil (residual soil) excavated from the building ground and other soil-like materials can be dumped and packed (consolidated) so as not to form a gap. In addition to FIG. 6, the means for constructing the pile wall 25 on the land side of the caisson 11 to better exhibit the water-imperviousness of the landfill can also be applied to the structure 10 shown in FIG. In the example shown in FIG. 1, for example, a steel sheet pile is driven into the water-impervious ground improvement portion 4, and a pile wall 25 is added to construct the same as in the example of FIG. 6. Can exhibit excellent water barrier properties.

  In the embodiment of the present invention, the case where an asphalt mixture is used as a water shielding material has been described. However, as the water shielding layer, a soil-based water shielding material or a concrete water shielding material can be used. It is also possible to perform construction by combining two or three kinds of the water shielding material. When constructing a combination of different types of the water shielding material, for example, it is constructed so that a water shielding material of an arbitrary thickness is laminated in layers, or a water shielding material of an arbitrary thickness. The layers may be constructed so as to be adjacent to each other in a row, so that the construction cost of the water shielding layer can be reduced. For example, when construction is performed using only an asphalt mixture as the water shielding material, the cost of the asphalt mixture is relatively high, so that sufficient water shielding can be achieved and the construction cost of the water shielding layer can be reduced. In many cases, it is strongly desired to construct in combination with other water shielding materials.

  In addition to the asphalt mixture, the material used as the water shielding material may be a soil water shielding material or a concrete water shielding material. For example, as a soil-based water-impervious material, a concrete-based water-impervious material can be used by adding an additive that prevents arbitrary solidification to clayey soil and performing a treatment that does not solidify. As a material, it is possible to use a material in which mortar or cement is mixed with soil or sand at a predetermined ratio in addition to concrete. And in the case of constructing the water shielding layer by laminating a plurality of layers of water shielding material, as shown in the examples described below, a plurality of types of water shielding material layers were laminated in any vertical and horizontal directions. It can be constructed as a water shielding layer.

In the example shown in FIG. 7, as described with reference to FIG. 4, when the caisson 11 is installed on the rock mass 2 that is strong and small in water permeability, the water shielding work between the ground and the lower part of the caisson is different. An embodiment of the present invention is described. When the rock mass 2 in the structure construction sea area can be excavated relatively easily, an excavation groove portion 5a having a predetermined depth and width is excavated with respect to the rock mass 2 using an arbitrary excavation means. And after constructing the foundation stone layer 6 by the predetermined thickness on the bottom face of the said excavation groove part 5a, the caisson 11 is mounted on it, and the earth-based impermeable material in the clearance gap (space part) inside the excavation groove part 5a Alternatively, it is possible to provide a lower water-impervious layer 20a by constructing a concrete water-impervious material with a predetermined thickness.
In addition, after the structure 11 is installed on the water-impervious layer 20a constructed by filling the soil-based water-impervious material and the space on both sides of the structure is further filled with the soil-based water-impervious material, The upper surface is constructed so as to be covered with the asphalt mixture layer 20b, and an integrated water shielding layer is constructed so as to protect the filling layer 20a of the soil-based water shielding material.

  As shown in FIG. 6, the example shown in FIG. 8 is a steel sheet pile (steel sheet pile, steel pipe sheet pile, steel box-type sheet pile, steel on the inland side (landfill side) of the caisson at a predetermined interval. A pile wall 25 is constructed by placing a pile of sheet piles such as H-shaped sheet piles in a row, and is connected to a caisson using a connection tool 26 such as a tie rod. And the well-known water shielding process is performed with respect to the connection part of the steel sheet pile which comprises the said pile wall 25, a vertical water-impervious wall is constructed | assembled, and water permeability is provided in the space part between the said pile wall 25 and the caisson 11. The partition which can maintain the water-proofing property more is constructed by applying the treatment to construct the packing layer with a small coefficient. In this embodiment, in the gap between the ground and the base of the caisson, it is possible to construct the water shielding layer 20A as described in each of the embodiments. In addition to the above-described structure, as the packed bed 27A, an asphalt mixture layer 27b is applied to the side surface of the caisson and the packed bed 20A, and a soil-based water shielding material layer 27a is formed between the wall 25 and the side portion. Install to. On the upper surface of the filling layer 27A, it is possible to construct a concrete water-blocking material with a predetermined thickness and use it as a water-blocking layer 27A in which three types of water-blocking materials are combined.

  In each of the embodiments of the present invention, as described above, in the water shielding material layers 20 and 20A constructed at the base of the caisson, a plurality of types of water shielding materials are laminated to further improve the water shielding performance. It is possible to construct a layer, and the thickness and the like of each material when the layers are laminated can be set as appropriate. In addition to the base water shielding material layer, the water shielding layer 27A constructed in a wall shape with a predetermined thickness on the side of the caisson also combines a plurality of water shielding materials having different properties as described above. Therefore, it is possible to cope with this by forming a water shielding layer. In addition, when an asphalt mixture is used as the water shielding material, the mixing ratio of asphalt components, aggregates, and other mixtures in the mixture correspond to the roughness of the sea area that constructs the structure, construction efficiency, etc. And can be created arbitrarily.

  In addition, as the soil-based water-impervious material, any clay-like material can be used. For example, a mixture of an emulsifying material, a component that suppresses precipitation, or the like is used for bentonite or the like. It is possible to maintain the properties as a water shielding material over a long period of time by holding the clay component so as not to be consolidated and solidified. Furthermore, as concrete-based water-insulating material, concrete and mortar formed at any blending ratio can be cast alone, but when placing relatively thick, a pebble or chestnut layer is used. After the construction, a concrete water-impervious material may be placed to construct a water-impervious layer in which these stone layers are integrated with the concrete water-impervious material.

It is explanatory drawing which shows the structure of the offshore structure of this invention. It is explanatory drawing of the joint water-impervious treatment part provided between caisson. It is a top view of the joint water-impervious treatment part of FIG. It is explanatory drawing of the example which builds an offshore structure on a bedrock. It is explanatory drawing of the example which builds an offshore structure without excavating a bedrock. FIG. 2 is an improved view of the offshore structure of FIG. 1. It is explanatory drawing of another Example of the layer of the water-blocking thing constructed | assembled in the base of a caisson. It is explanatory drawing of the modification of the water shielding process of FIG.

Explanation of symbols

1 submarine ground, 2 bedrock, 3 sedimentary layer, 4 impermeable ground improvement section,
5 excavation groove, 6 foundation stone layer, 7 end block, 8 embankment layer,
10 offshore structure, 11 caisson, 12 joint impermeable treatment section,
13 sealing member, 14 joint filling layer, 15 water shielding sheet,
16 presser blocks, 20 asphalt mixture layer, 21 end blocks, 25 pile walls, 26 fittings, 27 filling.

Claims (1)

A partition revetment that is constructed so as to surround a predetermined area in the sea area, and is divided to dump waste.
In the ground that builds the partition revetment, the impervious ground is improved as an impermeable ground, and a groove is provided at a predetermined depth and width.
Arranging structures like caisson in a row in the groove part, constructing a partition revetment as a section for dumping waste, and constructing a water shielding treatment at each connection part of the structure,
In the groove, a layer of a water shielding material is constructed at a predetermined height and width across the lower surface of the base of the structure and the side of the structure,
The construction method of the management type revetment characterized by performing a water-impervious treatment with the water-impervious material constructed between both the impermeable improved ground and the structure and the joint between the structures.

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