Filtering device for large depth vacuum drainage, compacting dehydration process and construction method of filtering device

A filter device in large vacuum drainage and compaction dewatering method and construction method thereof. Said filter device consists of long size sleeve and external sleeve pipe. The said long sleeve is made of welded multi-section inner sleeve pipe with vertical and triangle shape combined water absorbing holes in low end bottom sand storage part which has circular support base. The external sleeve pipe is made of same length multi-section with inner sleeve pipe, plural washer are set in inner surface of circle to form space between inner and external sleeve pipe, window shaped water gap with cover are set in external sleeve pipe.