Seismic Earth Pressures Measured During a Shake Table Experiment of Underground Structures

Download or read book Seismic Earth Pressures Measured During a Shake Table Experiment of Underground Structures written by Albert Luan Luu and published by . This book was released on 2013 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to better understand the behavior of underground structures when subjected to various levels of earthquake shaking, a large scale shake table experiment was conducted at E-Defense in Miki, Japan in February of 2012. A system of underground structures was installed inside a laminar soil container consisting of two vertical shafts connected via a cut-and-cover tunnel and two horizontal tunnels located independently near the bottom of the container. The underground structures were surrounded by sandy soil compacted to a relative density of about 35%. Recordings scaled to 50% and 80% intensity measured at the JR Takatori station during the 1995 Kobe earthquake were used as table input motions. Seismic soil pressures were measured along one of the vertical shafts using sensors specifically developed for this project. Soil pressures were found to be strongly acceleration dependent. The dynamic earth pressure acting on the underground vertical shaft increased with depth and consistently followed a triangular distribution up to shaft fixity. The point of application of the resultant force was found to be between 0.40-0.44 H on the shaft's height above its base. Comparison studies xii showed that the classical Mononobe-Okabe (M-O) theory did not provide a good match to the seismic earth pressures measured under small accelerations. However, a good fit in distribution and magnitude of earth pressures was observed when the accelerations approached magnitudes between 0.3-0.4 g. The Mononobe-Okabe method significantly over-predicted results for accelerations larger than 0.4 g.