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.
Geological, mineralogical and chemical characterization of Devonian kaolinite-bearing sediments for further applications in the ceramic (tiles) industry in La Paz, Bolivia
Clay minerals are widely distributed in Bolivia; among them, illitic clays are most common in the Altiplano where they are mined for use in the ceramic industry that has been growing in the last few years. In addition to illitic sediments, kaolinitic sediments have been recently discovered in sedimentary units in the Bolivian Altiplano. Residual ball clay occurrences in Devonian sedimentary units were studied as part of this work. Geological mapping and geophysical studies (ERT and GPR) were done for better understanding the origin of the deposits and were part of a preliminary study of the mineral potential to define the relationship with the host rock. Chemical and mineralogical techniques such as X-Ray Diffraction, Scanning Electron Microscopy and Inductively Coupled Plasma analyses were performed in samples from the studied area to verify the presence of kaolinite. Atterberg limits and behaviour of the raw material in ceramic specimens supported by chemical analyses show that this material is suitable for manufacturing tile ceramics. This study provides fundamental knowledge for deposit exploitation and future generation of an alternative source of employment for the inhabitants of Micaya.