Abstract: In a case study of the foundation rehabilitation of a high\|raised building, small diameter (Φ=150 mm) boreholes were drilled through the mat foundation. These boreholes were expanded into large diameter (Φ=400 mm) cast\|in\|situ concrete piles by utilizing the soil anchor borehole enlargement techniques. This method has the advantages of minimizing the existing foundation damage; controllable pile diameter; reliable single pile capacity; and fast construction. The case study suggests this method has good foundation improvement results.