The $110.7 million in bonds approved by Fairfax County voters last week for new schools, highway improvements and jail expansion will not actually be sold until next spring at the earliest, depending on the nation's volatile municipal bond market.

As a result, voters will see little progress on the projects they have approved for at least a year, perhaps longer. An exception will be construction on the $16.2 million expansion of the county jail, because the county already has allocated some funds to start work on it.

The county still has $74 million in unsold bonds, some dating back to l977 and 1978 when voters approved bonds for parks and schools. The county in most cases has put off selling those issues because of high bond interest rates during the past two years.

The Board of Supervisors next Monday may authorize the sale of $25-30 million of these previously approved bonds, with most of the funds to be used to buy and develop small parks across the county.

Because interest rates are still high -- 11 to 12 percent even for top-rated AAA bond jurisdictions like Fairfax, Arlington and Montgomery counties -- Fairfax may decide to avoid the conventional, long-term, 20-year bonds, says county budget analyst Charles Woodruff.

The supervisors may instead sell short-term, 5- to 10-year bonds or even two-year bond-anticipation notes, which would allow the construction projects to go forward and pin county hopes on bond market rates declining by 1984 -- a strategy also being considered by Arlington officials. Short-term bonds would save the county interest, since they pay lower rates than long-term bonds, but they would put a heavier load on taxpayers and the county budget, since payment of the loans would not be spread over 20 years.

The biggest chunk of the bonds approved Nov. 3 by voters is $57.2 million for a two-year program to build five new county schools and four school additions, and to refurbish nine other schools.

If bonds or notes are indeed sold next spring, officials plan to begin construction quickly on four of the five new schools: Franklin Elementary and Franklin Intermediate to serve the Franklin subdivision near Chantilly, and elementary schools at Newington Forest and Cherry Run. All are planned to open in the fall of 1983. The new Braddock Park Intermediate School is scheduled to open in 1984. All nine school refurbishment programs are to begin in 1982.

The $30 million in highway bonds, the first issue ever approved to maintain county roads -- a state responsibility -- will be spent over the next three years to back portions of 32 projects around the county. Voters will be asked to approve another $30 million bond issue in 1984 to finish the projects, most of which are small community road improvements, say county officials.

The $30 million is less than 5 percent of the $700 million in secondary road improvements needed in Fairfax County, according to state estimates, but the state presently has no money for them. The Virginia Department of Highways and Transportation estimates it ran a $27 million deficit in the fiscal year that ended in June, a figure that helped convince the legislature to allow the county limited authority -- $10 million a year -- to repair its roads.

Most of the previously approved but still unissued county bonds -- $54.5 million approved by voters in 1980 -- is for new Mount Vernon and Reston area governmental centers, a new county garage and renovations to the county courthouse. Woodruff said he expects the funds for these delayed projects will be borrowed at the same time that bonds or notes are sold for the 1981 projects approved by voters.