ABSTRACT:

A3,000kw × 14hr CAES is studied. (1) Bi - functional use of a shaft for CAES in the lower half and for aeration of sewage in the upper half. (2) Concrete tank prestressed by the stable gel pressure of heavy mud. (3) Concreting test of a ultra mini -caisson at a depth of 24m.

RESUME:

L'etude a ete faite sur un CAES de 3000kW × 14h. (1) L'usage bi -fonctionnel d' un puits pour cuve CAES dans la moitie inferieure et I'aeration dans la partie superieure. (2) Une cuve pre - pressurisee par la pression d' un gel stab le de boues lourdes. (3) Le test d'un mini caisson à une profondeur de 24m.

ZUSAMMENFASSUNG:

Studie an 3000kWx 14Std CAES (1) Bi-funktionale Anwendung eines Schachtes fur CAES in der unteren Halfte und Belueftung der Abwasser -Kanale in der oberen Halfte. (2) Betontank, vorgepresst durch "stable-gel " Druck von schwerem Schlamm. (3) Betontest eines CAES Mini -Senkkastens in 24m Tiefe.

1.
CONCEPT OF URBAN CAES (Fig.1)

Double public use CAES is consisted of lower half CAES tank sustained by hydraulic head from river or treated water and the upper half aeration deep shaft for sewage treatment. This was proposed as ECO CAESd by M.Hayashi. It has been reviewed and studied the feasibility as steel CAES tank, by JSd and ENAA. The authors are other private study group on concrete CAES tankd, which will be jointly tried with the ENAA group from 1995.

2.
CONCEPT OF PRESTRESSED CONCRETE CAES TANK BY GEL PRESSURE OF HEAVY MUD IN DEEP SHAFT

2.1 Principle of prestressed CAES tank by heavy mud geld:H M G (Table 1 and Fig.2) Table 1 summarizes the principle and design concepts of H M G method. Basic comparison between the conventional (tensile concrete structure) a n d pro pose d (compressive concrete structure) is illustrated in Fig.2. Expected pressure distribution of H M G method for concrete urban CAES tank is illustrated in Fig. 3 in which the lower half is prestressed by HMG against to the CAES pressure and the CAES pressure in the upper half is withstood by the steel air pipe. This heavy mud method can be applied to the tunnel type CAES and fuel gas tank, too.

3.
LONG TERM STABILITY OF HEAVY MUD GEL FOR 7 MONTHS

1) Mechanism of stable heavy mud, gel pressure and solidized pressure (photo 1- 2) Heavy mud is consisted of water, clay, weigh barite, viscosifier, dispersant and alkaline materials. The gel structure in mud progresses with time, and becomes stable. This stability is accomplished not only by the electro chemical equilibrium around the microscopic particles of clayey material and fairy dense barite materials, but also by the polymer chains bound the flocculates with the weigh particles. In general, three dimensional flocculated network of weigh particles becomes stable. Then, flocculated hydrostatic gel pressure takes place in the continuous columns of free water in the three dimensional net work of flocculated structures. If the continuous free water changed chemically to combine free water around the flocculated particles, the gel pressure will decrease as solidaization, and become stable as cease of the chemical reaction of free water with flocculated particles. Therefore, if the measured gel pressure of heavy mud decreased Δ, it informs somewhat solidaization of heavy mud (Fig.8) and the solidized bentonite water could be used as packing plastics with high impermeable cut off plug. Residual gel pressure is liquidus and effective for prestressing the subground structure and surrounding relaxed domain. (Fig. l, Fig.4 and Fig.7).

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