Metro's Blue Line trains will not run between Stadium-Armory and Federal Triangle stations today as workers continue to repair the breached barriers that let the waters of the Washington Channel inundate the subway Thursday night.

Metro General Manager Theodore Lutz announced that decision after a staff meeting yesterday afternoon. "We're on a day-to-day basis now," Lutz said. "We'll meet again Monday to decide if we can run Tuesday."

That means that commuters will be able to take the Blue Line from National Airport only as far as Federal Triangle. Trains will not run beyond Federal Triangle through the Southwest and Capitol Hill to the Stadium-Armory station.

Special bus service will be provided to fill the gaps.

Normal subway service will continue on the Red Line between Dupong Circle and Rhode Island Avenue NE.

Metro officials had hoped they would be able to return the Blue Line to full service today. That plan was scrubbed when complications developed as workmen tried to seal the opening in the subway tunnel that let the water in.

That opening is located generally between the Hogate's and Flagship restaurants on Maine Avenue SW. It is the end of a tunnel under construction that someday will carry Metro's planned Yellow Line from the Pentagon across the Potomac River and under the Washington Channel to the existing L'Enfant Plaza Station.

Two barriers in the Washington Channel and then a bulkhead sealing the opening gave way Thursday night and water poured into the concrete tunnel, rolled down the tube and into the L'Enfant Plaza station. There it overwhelemed the drainage system and flowed into the Blue Line below.

It flowed predictably downhill to Federal Center Station, knocking out electricla connections and switches as it went. The tide was stemmed later in the evening but the damage was done.

Contractors, using sandbags in the tunnels and pouring thousands of tons of fill to shore up the barricades, have the flow contained, Lutz was told yesterday. But before they can pump out the tunnel, they must place an absolutely secure bulkhead at the opening to make certain the subway is not again threatened.

That bulkhead - a 3/4-inch thick reinforced plate - was scheduled to go in early yesterday. But a warp developed during the welding operation and the installation had to be delayed until last night, according to Roy T. Dodge, Metro's assistant general manager for construction and design.

The contractors - a joint venture of Perini, Horn, Morrison and Knudson - recommended to Metro yesterday that full Blue Line service not be restored until the bulkhead and an additional new plug in the twin tunnels are in place. That would be Wednesday at the earliest.

"We will have to balance that - the umpety-umpth margin of safety - against the need for transit service to the public," Lutz said yesterday. "I want to make sure we make our own judgements on that."

In addition to the bulkhead, a large barrier - 160 feet long by about 35 feet wide - surrounds the opening to the tunnel where the water entered Thursday. The barrier is further divided into two 80-foot long compartments. That barrier, called a cofferdam, was first breached between 6 and 7 p.m. Thursday.Then the interior wall, then one of the two bulkheads leading to L'Enfant Plaza gave way. The other bulkhead remained in place, divers learned ysterday, Dodge said. The bulkhead that remained made no difference because of crossovers between the two tunnels.

The cofferdam and the interior barrier now are stabilized, Dodge said, and the rate of seepage into the tunnel is decreasing and under control. At no time was there a wall of water surging through a tunnel, but the rate of seepage increased steadily until it was controlled.

The Blue LIne segment of the L'Enfant Plaza station was virtually dry yesterday, although there was about 6 inches of sanding water behind the sandbags on the Yellow Line.

The major damage of the operating railroad was done at Federal Center SW, not at L'Enfant Plaza. Federal Center is the low point on that segment of the Blue Line. Water cascaded from the L'Enfant Plaza station down the track on which trains to National Airport normally would run. It hit the bottom of the hill just east of Federal Center Station.

The low point is an opening between the two tracks that allows for an x-shaped crossover between the National Airport and Stadium LInes. Water hit the bottom of the hill, gushed across the tracks and buried the crossover. Four switches were filled with silt.

Six pipe-like loops that transmit vital electronic signals to trains were filled with water. The train control room, the electronic heart of Metro, is at the mezzaine level at Federal Center. Had it been at track level, vital electrical panels also would have been flooded. In many stations, the train control room is at track level.

Metro maintenance crews replaced all four switch machines yesterday and cleaned and replaced the electronic loops. A diesel-powered work train and its crew members rolled from L'Enfant Plaza to Federal Center spraying down the tunnel and cleaning the electrical insulators that separate the electrified third rail from the ground.

Metro was planning to run test trains through the area last night to determine if its switches and electronic sensing equipment was working properly.

Metro officials have been concentrating on restoring train service and in providing buses to fill the gaps. Both of Friday's rush hours were disrupted as commuters sought to solve the puzzle. There is no subway service on Saturday and Sunday.

The question of why the barricades failed remains unanswered. Lutz said yesterday that Dodge has been ordered to conduct a full investigation. Dodge deferred on many questions, saying, "I want to get all of the facts before I determine who shot John."