Design of a new laminar soil container and its numerical verification for SSI and liquefaction tests

Abstract

This dissertation presents the design, development, and evaluation of an Enhanced Transparent Impermeable Laminar (ETILam) soil container for laboratory soil tests. The research addresses the challenges in replicating prototype responses under static and dynamic conditions, which are crucial for geotechnical engineering applications. By conducting a comprehensive review of existing soil test setups and various types of laminar soil containers, the study aims to enhance the design and functionality of soil containers, particularly for dynamic tests using shaking tables and centrifuges. The research begins by identifying the key aspects and essential characteristics of laboratory test setups. It emphasizes the importance of soil container boundary conditions on test performance. Different types of soil containers and their specifications are examined, concluding that laminar soil containers are the most effective for replicating prototype conditions in laboratory settings. The study then explores the limitations that need to be considered during the design of a laminar soil container, leading to the development of an initial design concept. To ensure the effectiveness of the design, potential materials for the laminar soil container were tested in the laboratory. Characteristic parameters of these materials were evaluated for use in numerical modeling. Plexiglas and Sikaflex Pro3 flexible sealant paste were selected for the container construction. The performance of the lamina frame under maximum stresses induced during dynamic loadings was verified using structural software, and the locations of lateral support points were determined. A new method was developed for preparing the required soil sample with the proper relative density. This method evaluates the relative density of the soil based on the diameter of the sieve opening and the height of raining, leading to the design of a new sand pluviation mechanism. Through numerical modeling, the effect of boundary type and expansion on the soil sample was studied. Different sinusoidal motions were applied to the model, and the proper motion was selected for numerical evaluations of the laminar soil container design. Based on a review of available containers and their movement mechanisms, various numerical models were developed and their performances compared with free-field test responses. An enhanced movement mechanism was developed to provide a response more closely resembling free-field conditions. This mechanism employs roller bearings and a flexible sealant moving mechanism between the laminas. The study also examined the effect of the lateral support system on the behavior of the laminar soil container. It was found that vertical support, in addition to lateral support, provides a better response for the laminar soil container. The expected performance of the laminar soil container during laboratory tests was studied using generated models. The soil-structure interaction performance was evaluated, and the effect of a Single Degree of Freedom (SDOF) system on soil performance was assessed. The design process, through numerical modeling, resulted in the manufacturing of the ETILam soil container. Its performance was evaluated through tests on an empty container on a shaking table and with soil samples during multiple tests. For studying the soil-structure interaction (SSI) effect, a test setup representing a pile-supported SDOF system was designed and manufactured. A series of laboratory tests were performed on this system, and some of the results were presented. The performance of the empty ETILam soil container was compared with numerical model results, revealing that the numerical results closely resemble the laboratory test results. However, the results obtained from the laboratory tests on the soil sample inside the container indicated that increasing the input motion frequency and acceleration led to discrepancies between the numerical model and laboratory results, necessitating more detailed analytical studies on the soil models in the software. In conclusion, this dissertation demonstrates the development and validation of the ETILam soil container. The study highlights the effectiveness of combining roller bearings and flexible sealant for laminar movement, the importance of proper boundary support, and the need for detailed numerical and laboratory analysis to accurately replicate real-site conditions for soil-structure interaction and liquefaction tests. The ETILam soil container represents a significant advancement in geotechnical engineering laboratory testing, providing a more accurate and reliable method for studying soil behavior under dynamic conditions.