Abstract: This paper presents a case history of the foundation construction under a preserved historical building. Aspects of partitioned bottom-up construction and partial covered excavation of the underground space under a historical building in soft soil area are discussed. Before the historical building was transferred to the permanent position for the required underpinning, the vertical supporting systems and the basement ceiling at the final location were constructed first. The excavation was partitioned in consideration of its complicated surroundings, the zone with the historical building was constructed in bottom-up method after the other one was completed. The region under the historical building was partial covered excavated. Diaphragm walls with four-layer reinforced concrete struts were utilized as the supporting structures. The monitoring data indicated the preserved historical building structure was safe and stable during the entire excavation and the lateral displacements of the supporting structures well met the protection requirements of the surroundings. The deformations in the short side or at the corner of long side were significantly smaller than those in the middle of the long side, and the wall deflections of the small zone were evidently smaller than those of the larger excavated area.

Key words: Soft Soil, Preserved Historical Building, Deep Excavation, Underpinning, Building Translation, Partial Covered Excavation