JP4801283B2 - Hybrid artificial ground constructed in ocean space and its construction method - Google Patents

Description

[Industrial application fields]
The present invention relates to a hybrid type ground constructed in an ocean space, and more particularly to an artificial ground combining a pile structure and a caisson structure and a construction method thereof.
[Prior art]
Conventionally, a plurality of construction methods have been proposed as means for constructing artificial ground in an ocean space.
The first proposal is a method of constructing artificial ground in an ocean space using a pile structure. That is, the pile structure construction method is a construction method in which a pile is placed on the seabed and an offshore building is constructed based on the pile. Since it is possible to drive a pile at a predetermined point, it is possible to drive a pile at an accurate point according to the design drawing. Moreover, although an offshore structure is manufactured using several piles, the rigidity of the seabed geology of the seabed between each pile and the flatness of the seabed are not ask | required. In other words, whether or not piles can be placed is only a matter of placing piles, and it is possible to build offshore buildings even if some flatness between each pile and rigidity of the seabed geology are impaired. It is.
The second proposal is a method of constructing artificial ground in an ocean space using a caisson structure. The caisson structure is a box-like structure having a size of about 15 m × 15 m, which is previously constructed on the land with concrete and steel. Inside the caisson structure is a hollow, transported in a floating state on the sea after providing a wall other than the upper surface on land, moved to the destination point in a floating state, and entered the seawater etc. into the interior at the installation point, The caisson structure is controlled to move up and down by the weight of the incoming water, and is submerged on the sea floor.
Furthermore, a landfill method exists as a third proposal. In other words, this is a simple conventional technique for replacing seawater and earth and sand while laminating a large amount of earth and sand on the seabed.
A fourth proposal is the float method. It is a method of laying large floating objects on the sea, and there is an advantage that floating objects can be manufactured in a free shape on land and that laying is easy.
[Problems to be solved by the invention]
However, some problems have arisen in these conventional methods.
In the first pile structure construction method, it is usually necessary to drive the pile to a depth that produces axial strength that can reach the hard rock and face the horizontal stress. For this reason, the driving time of the pile has increased. In addition, the work at sea has been a factor that further increases the construction time because the work cannot be performed if the sea conditions deteriorate.
Moreover, in order to cope with the stress in the horizontal direction, it is necessary to increase the diameter of the pile, but this point is also a factor for extending the placing time.
On the other hand, the second caisson structure method requires flatness of the bottom of the caisson. In other words, since the caisson structure is usually formed of a rectangular parallelepiped, the caisson structure may be inclined when the sea floor is not flat. Furthermore, the caisson structure is huge, and it is difficult to specify the installation position with high accuracy by controlling the position of the caisson structure in the sea where the base axis does not exist.
Furthermore, the third landfill method has a problem that a large amount of earth and sand is required and the construction period is significantly longer than other methods and the cost is increased. Moreover, the phenomenon of ground subsidence and land liquefaction after landfill has not been solved.
The float, which is the fourth method, cannot be used unless the wave height is 40 cm or less, and in order to use it normally, a breakwater is installed around the float in order to ensure the sea area to be used as a constant hydrostatic surface. On the other hand, the cost was added to the breakwater installation.
SUMMARY OF THE INVENTION An object of the present invention is to provide an artificial ground that has a high position control accuracy at the time of installation, has a short construction period, can cope with a wide range of required horizontal / vertical forces after completion, and a construction method thereof.
[Means for Solving the Problems]
In order to achieve the object, the hybrid artificial ground constructed in the marine space of the present invention is composed of caissons provided with pile structures placed on the seabed ground at the four corners of the side.
When there is a gap between the caisson and the seabed ground, the gap can be filled with fine sand, concrete milk, or mortar, so that it can be installed even on an uneven seabed.
Furthermore, since the caisson is made of steel shell or concrete shell, it is possible to provide an artificial ground suitable for cost and sea conditions.
In addition, the caisson and the pile structure can be stretched and joined at the joining point / joint surface so that the sea level of the artificial ground after completion can be adjusted freely.
By having a liquid storage tank structure inside the caisson, the space on the artificial ground and the space inside the artificial ground can be used effectively.
By having a living space structure inside the caisson, it becomes possible to build a cheaper living space at sea.
In the construction of the hybrid type artificial ground according to the present invention, a caisson comprising a rectangular parallelepiped having the same length as the specific interval after placing a pile structure at a predetermined interval at two points on a predetermined submarine ground The side of the width is set so as to be fitted between the pile structures, and the pile structure is further placed so that the opposite side is fitted and constructed in the marine space.
Pile construction is driven in a short time in four directions in the case of a quadrilateral planar work table centered on a fixed work table by using a pile driving device capable of driving multiple piles at the same time. Can be set up.
【Example】
Embodiments of the present invention will be described below with reference to FIGS.
FIG. 1 schematically illustrates the structure of a hybrid artificial ground constructed in an ocean space according to the present invention. FIG. 1A shows a schematic plan view, and FIG. 1B shows a cross-sectional view along AA.
In FIG. 1A, reference numeral 2 denotes a caisson, and its shape is an octagon obtained by cutting off the corners of the four corners of the square at an angle of 45 degrees with respect to each side. It joins with the adjacent caisson 2 at the sides corresponding to the four sides of the square. A pile 4 is arranged at the center of each small square space formed at the cut off four corners, and the pile 4 is coupled to the caisson 2 via a coupling portion 6 that can be expanded and contracted. Each caisson 2 is connected to the adjacent caisson 2 that contacts the adjacent caisson at each side and is adjacent to the adjacent caisson 2 via the pile 4 and the diagonally located caisson 2. The caisson 2 is composed of a steel shell caisson in which a plurality of H steels are used for the skeleton and a steel plate or the like is used for the side plate. However, it is not limited to the steel shell caisson, and may be a reinforced concrete shell whose skeleton is composed of reinforcing bars. In any case, the caisson 2 is formed in a hollow box shape having an inner top surface. The size of the caisson 2 is, for example, 15 meters deep, 15 meters wide, and 20 meters high in the case of an ocean having a water depth of 10 meters. Further, the pile 4 may be either a steel material or a concrete material.
FIG. 1 (B) shows a cross-sectional view of the artificial ground of FIG. 1 (A) cut along line AA. The caisson 2 is set on the seabed 8. Here, 10 indicates the sea level. The caisson 2 is coupled to the pile 4 by a plurality of coupling portions 6. The pile 4 is driven to the seabed 8 to a depth of 1 to 2 meters.
That is, regarding the horizontal stress, the frictional force between the caisson 2 and the seabed 8 and the horizontal stress are offset in the configuration of the present invention in which the caisson and the pile support the horizontal stress compared to the case where the horizontal stress is supported only by the pile 4. The For this reason, a large horizontal stress does not occur in the pile 4. On the other hand, in order to disperse the vertical force at the bottom of the caisson in the vertical direction, the pile 4 does not require axial strength, and the axial strength shared by the pile side and the tip of the pile required for the pile driving method is generated. Therefore, it is not necessary to drive piles deeply into the seabed, which was necessary for this purpose.
On the other hand, in the vertical direction, the pile 4 and the caisson 2 are integrated as described above, and the buoyancy of the caisson 2 cancels out the vertical friction force and the reverse friction force acting on the pile 4. For this reason, the vertical strength and horizontal strength of the artificial ground composed of the pile 4 and the caisson 2 are controlled. That is, the buoyancy of the entire artificial ground can be controlled by controlling the buoyancy of the caisson 2 by the amount of seawater injected into the caisson 2 and controlling the amount of seawater injected by the caisson 2 of the entire artificial ground.
Then, the construction method of a hybrid type artificial ground is demonstrated concretely using FIGS.
2 to 6, (A) shows a side view and (B) shows a plan view. As shown in FIG. 2 (A), a fixed work table 12 having a width of 50 meters and a depth of 50 meters is installed 10 meters above the sea surface at a water depth of 10 meters in the coastal area, and the fixing work is performed as shown in FIG. 3 (A). A cantilever 16 is provided at the end of the base 12, the beam length is 15 meters, a pile driving machine 18 is provided at the tip, and the upright pile pillar 4 is driven. Here, the pile driving machine 18 may be either a vibration hammer or a weight hammer.
As shown in FIG. 4, the caisson 2 manufactured in advance by a dry dog or the like is pulled by the towed ship 20 and is transported and fitted to three existing pile driving points, thereby enabling accurate subsidence.
The caisson 2 transported as shown in FIG. 5 is laid down to the sea bottom with its three corners in contact between the piles. If the caisson is box-shaped and has a bottom plate, water is poured into the caisson and set. Here, since caisson laying positioning is performed at the pile position, it is easier than positioning the caisson alone in the conventional method, and laying can be performed in a short time.
Furthermore, as shown in FIG. 6, the upper part of the caisson 2 that has settled and stabilized is shielded by a shielding plate 22 made of concrete or steel plate, and a pile is placed at one corner side portion where the caisson remains. Then, a cantilever 16 similar to that shown in FIG. 3 is provided on the pile facing the open ocean, and an upright pile column is driven from the cantilever 16 to the open ocean by 15 meters using the pile driver 18 provided. Subsequently, returning to the process of FIG. 4 again, the caisson is sunk so as to fit between the three piles that have already been placed. After that, the upper part of the caisson is shielded with concrete, and a pile is further driven in the remaining one corner side of the caisson that has been laid. By repeating this process across the fixed work table 12 in both the vertical and horizontal directions, piles are driven every 15 meters, and caisson is sunk between them. Installed in size. By starting from the original fixed worktable and repeating the above work in sequence, the caisson itself becomes a worktable in turn, resulting in a stable structure, and the construction can be promoted without being affected by sea conditions, so the process is based on complex sea conditions To eliminate the delay.
In addition, two or more pile driving machines 18 are connected in series, and the caisson is fitted using the piles that have already been placed in the correct position. After the caisson is placed in the correct position, the upper surface of the caisson is used as the work floor. It is also possible to improve the efficiency of pile driving by providing a carriage that moves over the cantilever. The construction period can be shortened by increasing the configuration and the number of pile driving machines 18 and combining the pile driving work and caisson fitting / sinking work.
Furthermore, as shown in FIG. 7, when the sea bottom is not flat, a pile is driven and the caisson is sunk until the most projecting point 24 on the sea bottom contacts the bottom of the caisson. Thereafter, it is possible to maintain flatness by pouring fine sand, concrete milk, or mortar into the sea bottom from the hole 26 provided in the caisson bottom in advance to fill the gap between the caisson bottom and the sea bottom.
【The invention's effect】
According to the present invention, the pile structure and the caisson structure are constructed in an integrated manner, and the vertical and horizontal proof stresses of the entire structure can be freely adjusted in order to function in an integrated form.
If the caisson upper surface is converted to a working floor and the structure of pile driving support mechanisms such as cantilever beams is combined with caisson insertion and subsidence appropriately, the influence of the surrounding sea conditions will be reduced, and the water depth that enables pile driving work For example, it is possible to respond appropriately to changes in pile shape / scale and wide changes in pile spacing. For this reason, an artificial ground consisting of a pile structure, a caisson structure, and a combination / hybrid structure thereof can be constructed in a short period of time centering on the work table on the sea surface, completely independent of the surrounding land. In addition, the construction cost can be reduced by shortening the construction period.
[Brief description of the drawings]
1A and 1B schematically illustrate the structure of a hybrid artificial ground constructed in an ocean space according to the present invention, in which FIG. 1A is a schematic plan view and FIG. 1B is a cross-sectional view taken along line AA.
FIGS. 2A and 2B show a method for constructing a hybrid artificial ground constructed in an ocean space according to the present invention, wherein FIG. 2A shows a side view and FIG. 2B shows a plan view.
FIGS. 3A and 3B are a (A) side view and (B) plan view of a pile driving device for a hybrid artificial ground construction method constructed in an ocean space according to the present invention.
FIGS. 4A and 4B show a method for constructing a hybrid artificial ground constructed in an ocean space according to the present invention, in which (A) a side view and (B) a plan view are shown when a caisson is transported.
FIGS. 5A and 5B are a side view and a plan view, respectively, (A) of a method for constructing a hybrid artificial ground constructed in an ocean space according to the present invention when caisson is set.
FIGS. 6A and 6B are (A) a side view and (B) a plan view of a further pile placing process, which is a method for constructing a hybrid artificial ground constructed in an ocean space according to the present invention.
FIG. 7 is a side view showing a method for constructing a hybrid artificial ground constructed in an ocean space according to the present invention when the sea floor is not flat.
[Explanation of symbols]
2 Caisson 4 Pile 6 Joint part 8 Sea bottom 10 Sea surface 12 Fixed work table 14 Positioning device 16 Cantilever 18 Pile driver 20 Towing ship 22 Shield plate on caisson 24 Sea bottom most protruding point 26 Filling material injection hole

Claims (8)

A hybrid artificial ground constructed in a marine space composed of caisson with four pile corners placed on the seabed ground. 2. The hybrid artificial ground constructed in an ocean space according to claim 1, wherein the gap is filled with fine sand, concrete milk or mortar when there is a gap between the caisson and the seabed ground. 2. The hybrid artificial ground constructed in an ocean space according to claim 1, wherein the caisson is made of steel shell or concrete shell. The hybrid artificial ground constructed in an ocean space according to claim 1, wherein the caisson and the pile structure are joined in a stretchable manner. The hybrid artificial ground constructed in an ocean space according to claim 1, further comprising a tank structure for buoyancy adjustment inside the caisson. The hybrid artificial ground constructed in an ocean space according to claim 1, further comprising a living space structure inside the caisson. A caisson made of a rectangular parallelepiped having the same length as the specific interval is placed between the pile structures after placing the pile structure with a specific interval at two points on the predetermined seabed ground. The hybrid artificial ground construction method is set up in a marine space by setting the position so that it can be placed next, and then sinking and covering the upper surface of the caisson with a shielding plate and using it as a work floor. 8. The construction method for a hybrid artificial ground constructed in an ocean space according to claim 7, wherein the pile structure is placed by a pile driving device capable of simultaneously placing a plurality of piles.

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