Investigating the Nail Walls Performance in Jointed Rock Medium
Evaluation of the excavation-induced ground movements is an important design aspect of support systems in urban areas. Geological and geotechnical conditions of an excavation area have significant effects on excavation-induced ground movements and the related damage. This paper is aimed at studying the performance of excavation walls supported by nails in jointed rock medium. The performance of nailed walls is investigated based on evaluating the excavation-induced ground movements. For this purpose, a set of calibrated 2D finite element models are developed by taking into account the nail-rock-structure interactions, the anisotropic properties of jointed rock, and the staged construction process. The results of this paper highlight effects of different parameters such as joint inclinations, anisotropy of rocks and nail inclinations on deformation parameters of excavation wall supported by nails. Keywords—Finite element, jointed rock, nailing, performance.
Three-Dimensional Responses of a Tied-Back Excavation through Clay
The three-dimensional ground deformations measured during construction of a 12.8 m deep tiedback excavation in Chicago are presented. The excavation was supported by a PZ-27 sheet pile wall and three levels of regroutable ground anchors. The excavation was made through granular soils into soft to medium stiff clays. Extensive field performance data were collected including lateral and vertical optical survey data and lateral inclinometer data. Construction procedures are summarized and correlated with monitoring data. The three dimensional pattern of ground surface deformations around the excavation is summarized. A performance-based relation to estimate the maximum horizontal ground movements for flexible wall systems as a function of factor of safety against basal heave and excavation depth is proposed. An empirical approach to estimate the distribution of ground movements parallel to a supported wall is presented.
Preparation and performance evaluation of swine manure bio-oil modified rubber asphalt binder
Abstract In order to study the effect of the preparation process of swine manure bio-oil modified rubber asphalt binder on the rheological properties of the binder, the matrix asphalt and asphalt rubber were used as the control group, and swine manure bio-oil modified rubber asphalt binders were obtained by three preparation processes. Then the rheological properties of five binders were evaluated by rotational viscosity, DSR, MSCR and BBR tests. The results show that the addition of swine manure bio-oil to asphalt rubber is beneficial to the workability, but cause negative effect on its high temperature performance, fatigue performance and low temperature crack resistance. The preparation method of premixing bio-oil and rubber powder can reduce the degradation of high-temperature performance of asphalt rubber caused by addition of swine manure bio-oil to a certain extent. The fatigue properties of the three bio-binders are close, and the critical temperature is less than 25 °C. The process of premixing bio-oil and rubber powder will increase the creep stiffness and reduce the low-temperature performance. However, the low-temperature performance of the binder obtained by this process is still better than that of the matrix asphalt and can meet the requirements of use. Therefore, it is recommended to use the preparation process of premixing bio-oil and rubber powder to prepare swine manure bio-oil modified asphalt rubber.