JPS6290408A - How to install a seawall using self-rigid mounds - Google Patents

Abstract

PURPOSE:To construct a high-strength revetment by easily setting a shell by a method in which a self-hardening slurry is charged into the dredging portion of the seabed ground to form a mound, and after the mound has reached a given strength, the setting of a steel sheet pile shell, is made. CONSTITUTION:The soft layer of the seabed ground is dredged, and a self- hardening slurry prepared by adding cement to dried cinder is charged into the dredged portion to form a trapezoidal mound. When the mound has reached a given strength, a steel sheet pile shell is set in the mound, and the same slurry as in the mound is placed into the shell. Concrete is then placed onto the slurry and covering stones are laid on the open sea side. When a given strength is reached by the mound, the steel sheet pile shell is set. The setting of the shell can thus be made easier and a high-strength revetment can be constructed since the mound continues to harden even after setting the shell.

Description

[Detailed Description of the Invention] "Industrial Application Field" This invention integrates the mount, revetment wall material, and filler material, eliminates scouring by waves and running water, and is resistant to external forces such as wave force and seismic motion. The present invention relates to a method for installing a seawall that can easily construct a seawall with excellent strength and stability.

"Prior Art" As is well known, construction of seawalls for ports, rivers, dams, etc. is difficult because there is generally a soft layer on the surface of the underwater ground.
b) Remove the soft layer and form a high quality sand layer. (b) Improve the soft layer to a good quality ground using soil improvement methods.

After these measures have been taken, for example, an enclosure is constructed from the bottom of the water to the surface using revetment walls such as caissons, steel pipe sheet piles, and steel plate cells. This is accomplished by depositing, settling, and depositing stones, and finally laying a heavy covering stone on the surface of the exposed mount.

``Problems to be solved by the invention'' However, the following problems existed in the construction of conventional two-legged seawalls.

(1) The ground where ground improvement has been completed is strong, and it will be extremely difficult to embed the revetment wall.

For example, driving a ``steel plate cell'' into a mount made of sand that has been compacted using the ``sand compaction method'' requires long-term vibration. This problem arises because the ground strength is high at the time of rooting.

(2) Filling material is added after the mount has solidified, so
There was a problem that there was no integrity between the mount and the filling material, which resulted in a decrease in the rigidity of the entire seawall structure.

(3) In addition, in the construction of seawalls using sheet piles,
Due to insufficient watertightness, filler sand would come out from the gaps between the sheet piles (a type of scouring), reducing the rigidity of the entire seawall.

"Means for Solving the Problems" Therefore, the present inventors conducted extensive research to solve the above problems, and as a result, they came to the following knowledge.

(i) If the ground strength is too high at the time of embedding, problems such as ``two feet'' will occur, but on the other hand, if the ground strength is too low, it will not be able to withstand external forces, especially in the case of steel plate cells and steel sheet piles. It disappears. In addition, the strength of the mount varies depending on the degree of waves, currents, etc., but generally speaking, if it has a compressive strength of about 20 kgf/cm2 at the end of the seawall construction,
There will be no scouring or washing away due to waves, etc. Therefore, by using a mounting material that is medium-strength at the time of embedding and becomes high-strength after embedding, it is possible to easily construct a revetment and obtain a highly rigid revetment. Furthermore, by using the same material as the mount material for the filling material, the mount and the filling material can be integrated.

(ii) If a hydrated self-hardening material, such as a slurry made by mixing L-drained earth and sand with cement, or a slurry made mainly of inexpensive materials such as coal ash, is used as the mounting material, as shown in Figure 2, the , a gradual hardening mount can be constructed. In particular, slurry using coal ash is
As shown in the figure, strength development can be controlled quite flexibly by adjusting the density.

When the density of coal ash in this slurry is increased, the slurry takes on a trapezoidal shape suitable for mounting after being added.

This invention has been made based on the above findings.

That is, the method for installing a seawall according to the present invention is to dredge the soft layer at the location where the mount is to be installed on the water bottom, fill this dredged part with a hydrated self-hardening material, leave it alone until the mount reaches the required strength, and then, This method is characterized by installing a revetment wall on this mount, and then inserting filler material.

"Operation" According to the above method, when the revetment wall is embedded, the mount has a medium hardness, so it can be easily installed, and even after installation, the mount continues to harden and becomes high strength. , it becomes possible to construct a seawall that is resistant to external forces. Furthermore, if the filling material to be put in after the installation of the seawall wall is made of a hydrated self-hardening material that is the same as the mount material, it is possible to obtain a seawall in which the mount and the filling material are integrated. Furthermore, if the mounting material and the filling material are made of the same material in this way, even if sheet piles are used, it is possible to construct a seawall with improved watertightness that will not be scoured.

Hereinafter, this invention will be explained in more detail with reference to Examples.

``Example'' Figure 1 shows the construction sequence. The soft layer (approximately 5 m) of the seabed ground was removed using a well-known method to a depth of 5 m, 20 m x 20
Dredge the area within m as shown in Figure 1 (a),
A self-hardening material with a dry density of 1.2 g/cm3, which was made by adding 5 wt% cement to dry coal ash, was put into this part to form a trapezoidal mount [Fig. 1(b)]. This mount was left for 1 to 3 days, and its -axial compressive strength was 5Kgf/a.
m", we installed steel sheet piles with a diameter of 10 m and installed a revetment wall [Fig. 1 (C)]. At this time, the vibration could be carried out in about the same time as conventional methods. After that, a slurry equivalent to the mounting material was poured into the revetment wall as a filling material, and concrete was poured on top of it [First
Figure (d)]. And finally, on the surface of the exposed mount,
The installation of the seawall was completed by laying large covering stones weighing approximately 0 to 100 kg [Figure 1 (e)]. The unconfined compressive strength of the mount 28 days after installation is 15Kgf/c
It was m2.

According to observations after construction, the stability of this revetment was very good, with almost no scour of the filling material or mounting material, and no subsidence of the concrete at the top.

"Effects of the Invention" As explained above, the method for installing a seawall according to the present invention involves dredging the soft layer at the location where the mount is planned to be installed on the bottom of the water, filling this dredged part with a hydrated self-hardening material, It is characterized by leaving the mount until it reaches strength, then installing a revetment wall on this mount, and then filling it with filling material.

Therefore, according to the method of this invention, when the revetment wall is embedded, the mount has a medium hardness, so it can be easily installed, and even after installation, the mount continues to harden and becomes high strength. , it becomes possible to construct a seawall that is resistant to external forces. Furthermore, if the filling material to be put in after the installation of the seawall wall is made of a hydrated self-hardening material that is the same as the mount material, it is possible to obtain a seawall in which the mount and the filling material are integrated.

Furthermore, if the mounting material and the filling material are made of the same material in this way, it is possible to construct a seawall with improved watertightness that will not be scoured even if a pile is used.

[Brief explanation of drawings]

Figures 1 (a) to (e) are for explaining one embodiment of the present invention, each showing the construction process of a seawall, and Figure 2 is a diagram showing a construction process suitable for the mounting material used in the method of this invention. FIG. 3 is a graph showing the development of strength over time of coal ash slurry, and is a graph showing the relationship between the density and developed strength of coal ash slurry suitable for the mounting material used in the method of this invention. Figure 2 Figure 3

Claims (1)

[Claims] Dredge the soft layer at the location where the mount is planned to be installed on the bottom of the water.
This dredged part is filled with a hydrated self-hardening material as a mounting material, and this mount is left until it reaches the required strength. Then, a revetment wall is embedded and installed in this mount, and then it is surrounded by the revetment wall. A method for installing a seawall using a self-hardening mount, which is characterized by inserting filler material into the section where the seawall is installed.