A New Technique and Its Application in the Conservation of Historical Masonry Constructions -underpinning by manual pipe-jacking

摘要

The structural damages, which result from the inadequate bearing capacity or the asymmetric support of foundation, are one of the crucial works in the conservation of historical masonry constructions. Firstly, the box girders are slowly and evenly jacked by the manual pipe jacking technique, and then casting the core beam to form a whole, so the construction is gradually situated on a "tray" with sufficient rigidity. Consequently, the structural damages caused by the inadequate bearing capacity or the asymmetric support of foundation is thoroughly treated. Based on the field test, the principle of the underpinning by manual pipe-jacking, the mutual effect mechanism between box girders and soil, the calculation of jacking force and its influence factors are investigated in detail, and the empirical formula of calculating jacking force is also presented.