Implementation and evaluation of the underwater crack repair in the hollow concrete block of the gravity wharf

Abstract

Concrete block quay wall is the most popular type of structures in the gravity wharf. The concrete block can be generally categorized into two types: solid and hollow concrete blocks. Compared to the solid concrete block, the hollow concrete block can reduce the usage of concrete significantly and increase the resistance to sliding and overturning. This paper studied the application of hollow concrete blocks in the gravity wharf of Qingdao Port. It was discovered that in the application, the main problem was the crack development in the hollow concrete blocks. The paper first analysed the reason of crack development in the structure by conducting laboratory model tests. It was found that the contact conditions between two hollow concrete blocks was the key of the crack development. In order to improve the performance of the structure of hollow concrete blocks, an effective scheme, which can repair the cracks in the underwater environment and increase the bearing capacity of the gravity wharf, is proposed. The scheme contains two main procedures. The first step is to use the invented mending material to fill up the cracks. The next is to use the grouting technique to bond the rockfill inside the block holes and the hollow concrete blocks together. The model tests, field tests in 1980s and 2010 have proved the effectiveness of the scheme. This paper provides reference for the construction of similar structures.