Underpinning of high storeyed building foundation using sheetpiles constructed with poly groutingis realized by combination of jet grouting and pressure grouting. Some jet parameters in jet grouting and newviews are presented on the base of investigation and field tests. Expected effects are obtained by application ofthese test data and views resulted from study and analysis in foundation reinforcement for No. l high storeyedresident building of Beijing No, 1 Housing Service Company.