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This research explores the responses of reconstituted Kaolin clay samples due to simulations of wildfires in the laboratory using heat guns for control heating. Two laboratory geophysical methods, bender element and electrical resistivity, were used to detect the changes in soil’s mechanical (shear modulus, Gmax) and hydraulic properties (electrical resistivity, ρ) in real time, while soil specimens were heated, up to 60°C, to partially represent the temperatures in a wildfire. Measurements were compared with samples that had not been heated. Results show that the Gmax values for the controlled samples were about 25% greater than those that were heated, which implied that heating causes soil strength reduction. Additionally, the electrical resistivity for the controlled samples was 55% higher than that of the heated samples, meaning that heating caused the kaolin specimens to be less permeable. Correlations between Gmax versus temperature (T) and water content were developed. Results also allowed for the development of electrical resistivity, temperature, and water content correlations. 

Numerical simulation of liquefiable soil under cyclic undrained loading is essential for predicting earthquake-induced deformation of geotechnical structures in liquefaction hazard evaluation. Successful simulation of soil response requires constitutive models that can reasonably predict soil behavior under dynamic loading. Many advanced constitutive models have been developed for soil liquefaction hazard evaluation in the past four decades. These advanced models are built on plasticity theories with different modifications and assumptions. Nevertheless, the core part of all models was mainly developed based on observations from constant-volume (CV) cyclic direct simple shear (DSS) tests. While CV tests are standardized in the widely recognized ASTM D8296-19, true-undrained (TU) cyclic DSS tests wherein pore water pressure (PWP) is directly measured have also been performed in academic research. CV and TU cyclic DSS data were successfully generated at California State University, Los Angeles (Cal State LA), from the same apparatus. In this paper, the PM4Sand plasticity model is calibrated using CV and TU data. The performance of CV- and TU-calibrated models is cross-compared with TU and CV data, respectively. While results suggest trends in liquefaction capacity predictions, further data is required for comprehensive validation. The outcomes of this paper also provide insight into the calibration of PM4Sand over a range of relative densities and loading conditions. 

Marine structures placed in the shallower seabed can experience pore water drainages with more complexity than those in onshore environments, particularly in coarse-grained soils where drainage is neither purely “drained” nor “undrained,” but Partially Drained (PD). However, current laboratory approaches for characterizing soil behavior are limited to modeling drainage conditions as fully drained or undrained. This paper presents results from a series of confined monotonic saturated simple shear tests under various drainage conditions on reconstituted medium dense to dense Monterey sand specimens to fill this knowledge gap. Although others have performed limited PD element-level tests under triaxial conditions, no documentation exists for tests using a simple monotonic shear configuration. To achieve PD, a special filter was fabricated and connected between the bottom of the specimen and the backpressure controller. The hydraulic filter comprises a series of needle valves to provide various hydraulic impedances. All simple shear tests in this paper were backpressure-saturated. Two different degrees of PD were considered and compared with fully drained and undrained conditions. Results show that the excess pore water pressure generation and measured volumetric changes in the PD tests are bounded between those measured from fully drained and undrained, proving the PD filter provided the hydraulic resistance to achieve PD condition. 

Dynamic characteristics of treated and untreated Bauxite Residue (Red Mud) are studied and compared using a cyclic simple shear device. Red Mud (RM) is the by-product waste from the Bayer process during aluminum production that has shown the potential of being reused as fill material in embankment construction, which can reduce the energy consumption of disposing of the mining waste and producing fill materials. There are limited studies on the dynamic characteristics of RM; furthermore, the bauxite slurry’s high alkalinity (pH > 12) is a challenge for reusing the material. Past studies have shown two effective and economic neutralization methods: (1) mixing with saline and (2) adding gypsum. This study utilizes a cyclic simple shear device to characterize the dynamic properties of the treated and untreated Red Mud. The experimental results are used to develop the liquefaction capacity curves for the three types of Bauxite Residue: untreated, treated with saline solution, and treated with gypsum, and the results show different liquefaction resistances after pH treatments. Untreated RM specimens show the highest liquefaction resistance, and saline-treated demonstrated the least liquefaction resistance.