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\"An exploration of the cutting-edge technology that will enable us to confront the realities of climate change. For decades scientists and environmentalists have sounded the alarm about the effects of global warming. We are now past the tipping point. As floods, storms, and extreme temperatures become our daily reality, \"Reduce, Reuse, Recycle\" efforts aren't enough anymore. In Hacking Planet Earth, New York Times bestselling author Thomas Kostigen takes readers to the frontlines of geoengineering projects that scientists, entrepreneurs, engineers, and other visionaries around the world are developing to solve the problems associated with climate change. From giant parasols hovering above the Earth to shield us from an unforgiving sun, to lasers shooting up into clouds to coax out much-needed water, Kostigen introduces readers to this inspiring work and the people who are spearheading it. These futurist, far- thinking, world-changing ideas will save us, and Hacking Planet Earth offers readers their new vision for the future.\"-- Amazon.com.

In this study, tests were conducted to investigate the influence of coal combustion product (CCP) leachates on the hydraulic conductivity of original, fiber free and artificial geosynthetic clay liners (GCLs). Sodium and polymer GCLs were permeated with two synthetic leachates representing the mining wastewater in CCP disposal facilities: coal combustion leachate (CCL), and trona ash leachate (TAL). The barrier performance of GCLs to CCL and TAL was discussed basically in terms of mass per unit area (MPUA). Regardless of GCL type, increasing the MPUA to 5.0 kg/m2 (Mb5 and MP-b5) led to a decrease in the hydraulic conductivity to CCL and TAL. However, the existence of bundles of fibers on both GCLs had a significant effect on hydraulic conductivity, especially when MPUA was low. To investigate the influence of fibers, fiber free Na-GCLs with MPUA of 3.0 kg/m2 , 4.0 kg/m2 , and 5.0 kg/m2 (Mb3FF, Mb4FF, and Mb5FF) were manufactured and subjected to hydraulic conductivity test with TAL. The hydraulic conductivity of fiber free GCLs were significantly lower that those of original GCLs. The rehydration effect was examined on Na-GCLs (Mb3 and Mb4) and using TAL. On the other hand, artificial GCLs (A-GCLs) with MPUA of 3.0 kg/m2 , 5.0 kg/m2 , and 7.0 kg/m2 were manufactured with needle-punching apparatus in the laboratory. The equipment was efficient to manufacture artificial GCLs. According to test results, it was seen that the effect of MPUA and bundles of fibers on the barrier performance of GCLs were significant in terms hydraulic conductivity to CCL and TAL.

The Hawaiian Islands have been a world-famous traveling spot for their unique tropical island view. But the particular geological formation of the islands and their unique locations have always proposed challenges for geotechnical engineers and geologists. For example, coral sand is widely encountered in coastal areas of tropical or subtropical regions. It can be found on most beaches in Hawaiian islands. Compared with silica sand, it usually exhibits weaker mechanical performance from the perspective of engineering geology. Thus, necessary soil improvements shall be applied to the coral. Considering the fragile and unique ecosystem, sustainable material with less carbon footprint and less environmental impact would be developed and selected priorly. Moreover, the infrastructures along the island have been facing coastal erosion issues from both physical erosion (waves) and chemical erosion (sea wind and seawater). The road embankment, the house embankment, the harbor, etc often require maintenance to sustain their service time. Due to the topography and climate, the windward side of the coastal area on Oahu is suffering from marine microplastics (MP) pollution issues. Furthermore, as an island state, hurricanes and tsunamis could also threaten the safety of islanders and infrastructures. Therefore, as a geotechnical major Ph.D. student, this dissertation would devote some potential solutions to the challenges. Firstly, a novel alkali-activation-based sustainable binder was developed for coral sand stabilization. The alkali-activated slag (AAS) binder material was composed of ground granulated blast furnace slag (GGBS) and hydrated lime with the amendment of biochar, an agricultural waste-derived material. The biochar-amended AAS stabilized coral sand was subjected to a series of laboratory tests to determine its mechanical, physicochemical, durability, and microstructural characteristics as well as durability. Results show that the addition of a moderate amount of biochar in AAS could improve soil strength, elastic modulus, and water holding capacity by up to 20%, 70%, and 30%, respectively. Moreover, the addition of biochar in AAS had a marginal effect on the sulfate resistance of the stabilized sand, especially at high biochar content. However, the resistance of the AAS-stabilized sand to wet-dry cycles slightly deteriorated with the addition of biochar. Based on these observations, a conceptual model showing biochar-AAS-sand interactions was proposed, in which biochar served as an internal curing agent, micro-reinforcer, and mechanically weak point.Secondly, a state-of-the-art deep-learning algorithm, Mask R-CNN, was utilized for the clayey soil crack detection, locating and segmentation. A comprehensive dataset including 1200 annotated crack images of 256×256 resolution was prepared for the algorithm training and validation. The proposed Mask R-CNN algorithm achieved precision, recall and F1 score of 73.29%, 82.76% and 77.74%, respectively. Besides, the algorithm gained a mean locating accuracy (APbb) of 64.14% and a mean segmentation accuracy (APm) of 47.59%. The detection performance of the Mask R-CNN was also compared with the U-Net in three different scenarios. The test results have demonstrated the superiority of the Mask R-CNN over the U-Net algorithm in crack detection, locating and segmentation and the algorithm could automatically process the crack characterization. Then, this dissertation proposed a state-of-the-art deep learning-based approach, Mask R-CNN, to locate, classify, and segment large marine microplastic particles (fiber, fragment, pellet, and rod). The fully trained Mask R-CNN algorithm was compared with U-Net in characterizing microplastics against various backgrounds. The results showed that the algorithm could achieve Precision=93.30%, Recall=95.40%, F1 score=94.34%, APbb=92.7%, and APm = 82.6% in a 250 images dataset with white background. The algorithm could also achieve a processing speed of 12.5 FPS. The results obtained in this study implied that the Mask R-CNN algorithm is a promising microplastics characterization method that can be potentially used in the future for large-scale surveys. Finally, a video instance segmentation algorithm was trained to locate, identify, and segment soil cracks in a real-time video stream. The algorithm could record the cracks' locations and numbers simultaneously. Besides, the crack ratio of clay could be calculated by crack pixels divided by total clay pixels among the entire soil cracking process. Furthermore, Structure from Motion (SfM) has been applied to reconstruct the 3D soil desiccation models. The soil crack can be detected in a 3D point cloud graph and highlighted. A series of 3D parameters like depth, volume, and cross-section profile can be obtained for future analysis. The proposed video instance segmentation method has demonstrated the potential application for real-time crack alerts and monitoring of geotechnical infrastructures via surveillance cameras.

Clays, whether deposited on the seafloor or resedimented in the lab, generally exhibit a type of anisotropy called transverse isotropy (TI) due to layering and grain/void orientation from compaction. Sediments also experience an array of stress states due to varying geologic conditions. It is important to systematically measure how velocity anisotropy evolves with stress path to improve subsurface geophysical models, understand dynamic stress-strain relationships, and perform informed geotechnical site characterizations. This research experimentally measured velocity anisotropy in intact vs resedimented Boston Blue Clay (BBC), as well as stress path velocity dependence, vertical velocities during undrained shear, and velocity anisotropy from 1 to 10 MPa of resedimented Gulf of Mexico Eugene Island Clay (RGoM-EI). Results for intact versus resedimented BBC agree, and all clays exhibited low horizontal vs vertical velocity anisotropy and inclined compressional wave anisotropy (Thomsen parameters ≤ 0.3). Shear stress was found to affect wave velocity immensely, and results suggest that stress path compression-derived equivalent velocity curves resemble Modified Cam Clay (MCC) iso-porosity ellipses. Undrained shear-derived iso-velocity curves agree with those from normal consolidation as well, implying that porosity/density controls vertical P-wave velocity (Vp) in normally consolidated clays.This thesis also improves upon shear and longitudinal (Vs and Vp) wave velocity measurement technologies developed at Tufts Advanced Geotechnical Laboratory and MIT. Prior technology exhibited signal noise issues that affected horizontal wave velocity interpretation. Additionally, apparatus compressibility was not considered in the previous studies, leading to offset velocity measurements. The signal issue in the horizontal wave arrivals was found to be caused by improper grounding, originating from a shared ground pin of both receiving and sending actuators. Apparatus compressibility was then measured, and for a uniaxial test at 10 MPa axial effective stress, the velocity offset was found to be 13.7 m/s. Since the P-wave velocity range of interest is greater than 1500 m/s in sea water, this deviation produces a 2.5% error in vertical P-wave velocity (VpV). This implies that all prior VpV were overestimated by up to 2.5 percent, though this error is now corrected for in post-processing.

Improving the engineering properties of the subgrade soil by means of chemical stabilization is known to enhance the construction conditions in plastic soils and result in a reduction in design thickness requirements of the base, subbase, and wearing course in a layered pavement structure. This can also potentially lead to an increase in pavement life. This study was undertaken to study the effect of hydrated lime and Portland cement used as a stabilizing agents on the strength properties and the cracking resistance of a clayey soil collected from South Dakota. Hydrated lime was mixed with the collected soil by 2%, 3% and 5% and Portland cement was blended at 7%, 9% and 11% by the weight of the soil. Different tests, namely Particle size distribution, Atterberg limits, pH, Proctor test, freeze-thaw (F-T) cycles, unconfined compressive strength, and semicircular bend test were conducted before and after treatment with hydrated lime and Portland cement. The results indicated that use of 1% cement was more effective than 1% lime in improving soil’s shear strength. In general, shear strength of the natural soil was found to become more sensitive to F-T cycles with increasing both Portland cement and hydrated lime contents. The flexural stiffness and fracture energy of the natural soil were found to improve by stabilizing it with both lime and cement. This improvement was more pronounced when Portland cement was used. Reduction in the flexural stiffness and fracture energy of the lime-stabilized soil was found to be more sensitive to F-T cycles than cement-stabilized soil. The only stabilizing agent found to be capable of improving the flexibility index of the natural soil was hydrated lime. Cement-stabilized soil was concluded to be highly brittle and may result in instantaneous propagation of the crack in the whole section after reaching the peak load. Therefore, the use of cement stabilization should be carried out more cautiously to avoid premature crack