Research on Effective Embedded Depth of Bottomless Steel Sheet Pile Cofferdam in Rock

This study investigates the effective embedded depth of bottomless steel sheet pile cofferdam in hard rock. The bridge crossing the north main stream of the Dongjiang River in Huizhou City is used as a case. Based on the cofferdam-aided pouring of the pile cap of pier No. 76 , the interaction of the steel sheet piles, backfill soil and hard rock was numerically simulated to analyze the influence of an embedded depth of 0 to 2. 4 m on the equivalent stress and deformation of steel sheet piles as well as the equivalent stress distribution in hard rock of the guide hole. It is shown that the embedded depth has minor influence on the equivalent stress and deformation of the steel sheet piles. Regular and intermittent equivalent stress concentrated spots in the top part of guide holes were observed, which were distributed along horizontal direction and were the damage sensitive areas of rock skirting in the guide hole. When the embedded depth is varying, the distribution heights of the equivalent stress in the hard rock of the guide hole along the horizontal and vertical directions are similar. Compared with an embedded depth of 0 m, the maximum stress in the equivalent stress concentrated area in the guide hole is significantly reduced about 14% at an embedded depth of 1. 5 m, which is favorable to the stability of the hard rock of the guide hole. As the embedded depth increases above 1.5 m, the equivalent stress in the hard rock at the guide hole will not decrease as the embedded depth keeps increasing, as a result, the stability of the hard rock in the guide hole could not be furtherly improved. © 2023 Wuhan Bridge Research Institute. All rights reserved.