Mortar using seawater and sand was the material studied here. The mortar specimens, in particular, were cured in natural seawater. The foci development in the mortar was the principal interest in this study. The on-line damage detection experiment art, including dynamically global MSHCT (Multi-Slices Helical Computer Tomography) scan and the local detection of EDS (Energy Dispersive Spectrometer), SEM (Scanning Electron Microscopy), and XRD (X-ray Diffraction) was designed to research the foci development in the mortar specimen. The mortar specimens with 70-day age were produced and investigated by the on-line damage detection experiments. The experiment results indicated that the mortar using seawater and sand offered appreciable strength at the early age, at least, although some saline minerals were generated during the preparation. The residual strength of the mortar was above 13 MPa, which helped to prevent the sharp damage of engineering bodies. The micro-interfacial behavior and the parental foci development controlled the damage evolution in the mortar using seawater and sand, the performance of which was still the adjustable one by composition optimization.

A rock-filled concrete (RFC) dam is an original dam construction technology invented in China nearly 20 years ago. The technology has been continuously improved and innovated upon, and the accumulated rich practical experience gradually formed a complete dam design and construction technology. Seismic design is a key design area for RFC dams that still requires more investigation; therefore, this article attempts to address some questions in this area. In the article, the seismic design for a curved gravity dam, currently under construction, is compared for RFC and conventional vibrating concrete (CVC) dam alternatives based on American design documents. The conclusions drawn from investigations include the following: The displacement and stress distributions in both the CVC and RFC alternatives are similar, but the maximum computed values for the RFC dam model are slightly smaller than those for the CVC one, while the sliding resistance of both dam alternatives can meet the requirements of the specifications. Regarding the nonlinear seismic analysis results, the extent of damage in the RFC dam model is significantly reduced when compared with the CVC model, which can be explained by the higher cracking resistance of RFC. In general, the seismic performance of the investigated dam made of RFC appears to be better than that of CVC.

A high-order doubly asymptotic open boundary (DAOB) for the modeling of a semi-infinite reservoir with constant cross section is developed, in which the compressibility of water and the absorption characteristic of a reservoir bottom are considered. The dynamic stiffness matrix is approximated by a doubly asymptotic continued fraction solution with an additional factor matrix to improve its numerical robustness. The continued fraction solution converges throughout the entire frequency range quickly as the increasing orders of approximation and is verified by a rigid dam example. Introducing the auxiliary variables, a temporally local high-order DAOB is formulated. Coupling the high-order DAOB with the finite-element method (FEM) straightforwardly, an efficient procedure for the transient analysis of dam–reservoir interaction is developed and implemented in an open-source finite-element software OpenSees. Gravity dam and arch dam examples subject to dynamic loading conditions including the dam–reservoir interaction are analyzed. It is demonstrated that this proposed procedure is of high accuracy and computational efficiency.