Geotechnical factors influencing earth retaining wall deformation during excavations

This study aims to identify and evaluate the significance of the key design factors that impact the stability of Earth retaining wall anchor-supported structures during excavations in urban areas. Although there are many previous studies on the deformation of Earth retaining walls during excavation, there is a lack of verification studies that quantitatively examine the stability of various influencing factors such as wall, ground characteristics, and external influencing factors. To this end, finite-element analyses were conducted, and their results were compared and validated with field measurements. These comparisons demonstrated that the numerical modeling technique employed in this study effectively simulates the wall’s behavior under excavation conditions. Subsequently, the impact of the main design factors, including ground properties, external conditions, and structural stiffness, on the behavior of the wall was quantitatively assessed by applying variation ratios. The findings indicate that the horizontal displacement of the wall, induced by excavation, is significantly dependent on the unit weight and shear strength of the soil. Conversely, the groundwater level location, surcharge load, and structural stiffness exhibit a relatively minor effect. Finally, the variability of the main design parameters was investigated, considering the specific ground layer where the wall is installed, revealing distinct influences of these variables across different ground layers. Consequently, it is expected that the importance of the influencing geotechnical factors will be selected and used for predicting the behavior of Earth retaining walls and actual design, which will help to efficient wall design

Behavior of a full scale tieback wall in sand

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Sealing impoundment leaks by electrophoresis

Vita.Electrophoresis is an innovative technology to seal leaks in operating surface impoundments that does not require removal of impoundment contents, exposure of workers, or locating the leaks. A suspension of clay particles is added to the impounded liquid. The cathode (negative electrode) is placed inside and the anode (positive electrode) is placed outside the leaking impoundment. An electric field is imposed externally across the geomembrane liner through the leaks. The clay particles migrate to the leaks under the influence of the imposed electric field to form a clay cake seal. This dissertation presents the results of various kinds of laboratory experiments conducted to evaluate the use of an electric field to direct migration of clay particles to a leak, and the hydraulic integrity of the resulting seal. The effects of clay mineralogy, clay particle concentration in suspension, size of leak, electric field strength, and the presence of background metal ions in suspension on migration and cake formation were evaluated. The sealing effectiveness of the resulting clay cakes were evaluated by measuring the hydraulic conductivity, and the internal structures were examined using nuclear magnetic resonance imaging techniques. The effect of the presence of dissolved methanol on the electrophoretic mobility of bentonite was investigated. The results of cake formation experiments indicate that the cake growth rate was dictated by: (1) deposition of clay particles migrated by electrophoresis and gravity; and (21) consolidation of the particles. The cake growth rate and pattern were complex due to continuously changing particle distribution and increasing particle interference with time. The stability of the suspension was a key factor affecting the structural integrity of clay cakes. The dimensions of clay cake increased with increasing electrical energy consumed in system