Abstract: A multistage wedge-shaped jack apparatus is provided for jacking up and maintaining a heavy structure for mounting and replacing bearing units interposed between the heavy structure and a lower base while considerably increasing the jack amount without increasing the overall length of the apparatus. A wedge-shaped drive member (1) and a wedge-shaped pressure receiving member (2) are laminated on a base plate (3) and brought into contact with each other with the respective slant surfaces (11) and (21). A push/pull drive device (6) is provided in cooperation with a reactive force receiving device (5) for limiting a movement of the wedge-shaped pressure receiving member. A single or a plurality of auxiliary wedge-shaped members (7) are provided to the wedge-shaped drive member to be detachably coupled with each other in order.

Abstract: A method of raising/supporting a bridge or the like on a lower structure involving sliding an upper wedge-shaped pressure receiving member having a slope on its lower face and a wedge-shaped drive member having a slope on its upper face relative to each other on their slopes by drive mechanism for driving the wedge-shaped drive member, to raise the upper face of the upper wedge-shaped pressure receiving member with respect to the lower structure. The method further involves regulating the upper wedge-shaped pressure receiving member and the wedge-shaped drive member from their relative movements after the bridge has been raised. The method further involves removing the drive member after the regulation of the relative movements of the upper wedge-shaped pressure receiving member and the wedge-shaped drive member.