Shallow landslide mitigation through bio-inspired techniques in clay soils: the example of Trichoderma asperellum

The experimental investigation described in this thesis investigates the possibility of using fungi as an environmentally friendly and natural way to enhance the mechanical, hydrological, and physical properties of soil. Three varieties of clayey soil have been chosen for this study in order to be treated with fungus. The investigation's goal is to assess how fungal activity affects the strength, structure, and water-soil interaction of soil. To assess the physical behavior of the treated soils, the Atterberg limits test was conducted. To evaluate the impact of fungal treatment on the hydrological properties of the soils, the HYPROP and WP4C devices were used to obtain Soil Water Retention Curves(SWRC). The degree of soil hydrophobicity was determined using the Water Droplet Penetration Time (WDPT) test. To investigate the mechanical behavior, direct shear tests and oedometer tests were performed to determine shear strength parameters and consolidation characteristics. To understand the hydromechanical behavior of this treatment, evaluate by reconstructing the Soil Suction Characteristic Curves (SSCC) based on the results of SWRCs. At the end, Scanning Electron Microscopy (SEM) was conducted to obtain better visualization of fungal interactions within the soil matrix. The novelty of this project lies in addressing a gap in the current literature, where only a limited number of studies have explored fungal treatment for soil improvement, most of which focus primarily on sandy soils. In contrast, this research investigates the use of fungi in clayey soils. Another innovative aspect of this study is the comparison of three distinct fungal application methods: mixing, surface application, and injection, to evaluate their effects on soil water retention curves. The results show that the presence of fungi influences the physical, hydrological, and mechanical properties of the soil. Moreover, the method of fungal application in soil water retention has an impact on the results, as each technique leads to different results. In conclusion, the study demonstrates the potential of fungi as an eco-friendly and effective method for improving clay soils. By comparing the results across different application methods and performing engineering judgment on the findings, this research offers practical insights for the implementation of fungi.