JPH0341605B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for constructing a core for the purpose of water-blocking a foil-type dam such as a rock-filed dam or an earth dam. Conventionally, foil-type dams have used natural soil such as clay or heated asphalt concrete as the core material, and have built the embankment by mounding it together with the embankment material. However, there are problems with natural soil such as clay as a core material, such as difficulty in obtaining high-quality natural soil, and the fact that it is easily influenced by the weather, making it difficult to adjust the water content ratio. In addition, heated asphalt concrete has problems such as the need for large-scale heating equipment and poor construction efficiency because it is difficult to build up the concrete to a thickness greater than necessary. As a technique for solving such problems, for example, Japanese Patent Application Laid-Open No. 54-32258 discloses a method for constructing a core of a file type dam, which will be described below. FIG. 1 shows the main part of the construction method disclosed in the above-mentioned publication, and is a schematic side view showing the construction method of a so-called central core type file type dam. In the construction method disclosed in the above publication, before constructing the core, foundation treatment is performed by performing curtain grouting 2 by injecting cement or the like into a predetermined position within the foundation rock 1. Next, a core 3 made of cement-bituminous mortar or cement-bituminous concrete is formed on the foundation rock 1 using a formwork, lock or random zones 4 are set on both sides of the core 3, and the material of each zone is At the same time, embankment work will be carried out by pouring out and compacting. By repeating the above-mentioned work and constructing the dam up to the top of the dam, the desired foil type dam 5 is constructed. However, with this type of core construction method, there are concerns about the watertightness of the joints of the core, and the formwork must be installed and removed repeatedly, making construction complicated and prolonging the construction period. There was a problem. The present invention has been made in consideration of the above-mentioned problems, and its purpose is to efficiently construct the core of a foil type dam without being affected by the weather.
It also aims to provide a new construction method that can be constructed economically. In order to achieve the above object, the present invention provides a method for constructing the core in the center of the embankment body of the foil type dam after constructing the embankment body when constructing the core of the foil type dam. The core is constructed by excavating from the upper side of the embankment while filling a self-hardening stabilizing liquid with a groove that overlaps the upper end of curtain grouting provided in the foundation ground, and hardening the self-hardening stabilizing liquid. The self-hardening stabilizer is characterized in that it contains 3 to 40% bentonite clay and 8 to 16% cement. That is, the basic concept of the present invention is not to build a file type dam in parallel with the work of heaving the embankment body material and the work of heaping the core material, as in the past, but to construct the heaping work of the embankment material. After constructing the foil type dam in advance, the construction work of the core material inside the embankment is carried out later. Embodiments of the present invention will be described below with reference to the drawings. FIG. 2, FIG. 3, and FIG. 4 are schematic side views showing the construction order of the method for constructing a central core type foil type dam according to the present invention. First, in Figure 2, curtain grouting 2
A lock or random zone 4 is created by embankment work on the foundation rock 1 that has been foundation-treated. By repeating this embankment work up to the crest of the embankment, the embankment body 5 of a coreless film type dam is constructed. Next, as shown in FIG. 3, using an excavator 7 from the top 6 surface of the embankment body 5 of the embanked film-type dam without a core, a self-hardening stabilizing liquid, which is a stable liquid, is poured into the embankment body 5. A trench hole 9 is excavated while filling the hole 8. When the tip of the groove hole 9 is formed to a depth that excavates the upper end of the curtain grouting 2, the excavation of the groove hole 9 is completed, and the self-hardening stabilizing liquid 8 in the excavated groove hole 9 is hardens over time,
Converted into a unit hardened wall. Next, in FIG. 4, a trailing unit hardened wall is formed in the longitudinal direction of the embankment body 5 so as to overlap and connect with the preceding unit hardened wall, and when such operations are repeated, the hardened unit wall becomes lateral. A directionally connected continuous wall or core 10 is constructed. The self-hardening stabilizer 8 used in the present invention has a content of 3 to 40%
bentonite clay, 8-16% cement, and an optional retarder. The properties of the cured product of this self-hardening stabilizer are shown in Table 1.
As shown in Figure 2, it shows impermeability when the permeability coefficient (k) is on the order of 10 ^-6 to ^{10 -7} cm/sec, and it is also made of rock or random material with a deformation coefficient (E50) of 200 to 500 m/ ^cm2 , which indicates flexibility. This value is similar to that of the embankment body 5 made of wood, indicating that it follows the deformation of the embankment body 5.

[Table] In addition, when excavating a groove in the embankment body 5 made of a material with a large particle size, for example, a suitable length of polyester fiber (especially KS fiber) is added to the self-hardening stabilizing liquid 8 as a sludge prevention material. (a good example), it is possible to maintain the stability of the trench wall without slippage. Moreover, in addition to constructing the cores 10 in a single row in the longitudinal direction of the embankment body 5, it is also possible to construct the cores 10 in multiple parallel rows. As described in detail above, in the present invention, after constructing the embankment body of a file type dam, the core is constructed as a continuous wall formed by hardening of the self-hardening stabilizing liquid. The construction work can be carried out independently of the preceding construction of embankment material, which is extremely advantageous in terms of construction efficiency and shortening the construction period. Furthermore, in the construction method of the present invention, the curtain grouting in the foundation ground and the core are polymerized and connected, so that sufficient water-stopping properties are ensured. Furthermore, the subsequent core material construction work can be carried out without being affected by the weather, and since the core uses a self-hardening stabilizing liquid adjusted to a specific range, it has excellent water-impermeability and a film-like structure. An ideal core with flexibility that follows the deformation of the type dam can be constructed.

[Brief explanation of drawings]

FIG. 1 is a schematic side view showing the construction method of a conventional central core type file type dam. Fig. 2 is a schematic side view of a rock-file type dam without a core built by embankment work according to the present invention, and Fig. 3 shows the core construction work inside the embankment of the lock-file type dam without a core shown in Fig. 2. Figure 4 is a schematic side view of a lock-file type dam completed through core construction work. 4...Lock or random zone, 5...
Lock file type dam, 8...Self-hardening stabilizer,
9...Slot hole, 10...Core.

Claims (1)

[Claims] 1. When constructing the core of a foil type dam, the core is constructed in the center of the embankment body of the foil type dam after the embankment body is constructed, the core being installed on the foundation ground. excavating a groove from the upper side of the embankment body while filling it with a self-hardening stabilizing liquid, which overlaps with the upper end of the curtain grouting;
It is a continuous wall constructed by curing this self-hardening stabilizing liquid, and the self-hardening stabilizing liquid has a
A method for constructing a core of a fill-type dam, characterized in that the core contains 8% to 16% of bentonite clay and 8 to 16% of cement.