The effective dynamic viscosity of a soil-rock mixture (S-RM) serves as a essential parameter for simulating flowlike landslides in the context of fluid kinematics. Accurate measurement of this viscosity is significant for understanding the remote sustainability and rheological properties of landslide hazards. This study presents a method for determining dynamic viscosity, incorporating experimental measurements and numerical inversion. The experiment involves monitoring the movement of S-RMs with varying water content and rock block concentration, followed by the calculation of centroid displacements and velocities using digital image processing. The power-law model, combined with computational fluid dynamics, effectively captures the flow-like behavior of the S-RM. A grid search method is then employed to determine the optimal parameters by comparing the predicted centroid displacement with experimental results. A series of flume experiments were conducted, resulting in the observation of spatial mass distribution and centroid displacement variations over time during soil-rock movement. The dynamic viscosity model of the S-RM is derived from the experimental data. This dynamic viscosity model was then employed to simulate an additional flume experiment, with the results demonstrating excellent agreement between the simulated and experimental centroid displacements. Sensitivity analysis of the dynamic viscosity model indicates a dependence on shear rate and demonstrates a high sensitivity to water content and rock block concentration, following a parabolic trend within the measured range. This research contributes to the fields of geotechnical engineering and landslide risk assessment, offering a practical and effective method of measuring the dynamic viscosity of S-RM. Future research could explore additional factors influencing rheological behavior and extend the applicability of the proposed method to different geological environments.

The occurrence of settlements induced by soil liquefaction will exert a substantial influence on buildings situated in earthquake-prone regions. Previous studies integrated the viscous-damping force into the governing equation to characterize building settlements and considered the apparent viscosity as an important parameter. The existing equation can be utilized to predict the settlement magnitude in the final stage as well as its evolution. However, due to the insufficient description of apparent viscosity, it is commonly regarded as a constant during the process of evaluating settlement. When adopting this mechanism, the evolution of building settlement often proves inadequate in fully capturing actual conditions. The aim of this study is to propose a prediction model for estimating liquefaction-induced settlement of shallow-founded buildings, which is formulated by an analytically differential equation. The proposed model incorporates the time-dependent viscosity of liquefied soil and introduces the concept of a soil column submerged in liquefied soil during seismic shaking. The evolution of settlement and the final settlement magnitude induced by soil liquefaction is evaluated through the analytical estimation, and these findings are subsequently compared with the results obtained from centrifuge experiments and numerical simulations. Furthermore, the proposed model is employed to investigate the correlation between building settlement and the geometric characteristics of shallow foundations. The proposed methodology shows considerable promise as an intermediate tool for assessing building settlement, offering practical simplicity in real scenarios.

Accurately describing the solid-like and fluid-like behaviors of granular media is crucial in geotechnical engineering. While the unified frictional-collisional model, integrating rate-independent frictional and ratedependent collisional stresses, is widely used for solid-fluid phase transitions, an effective model is still under investigation, and comprehensive analyses are lacking. This study addresses these gaps by developing an enhanced elastoplasticity-based frictional-collisional model. The frictional stress is modeled using a critical-statebased elastoplasticity approach, and the collisional stress is formulated through an enhanced kinetic theory incorporating particle stiffness. Subsequently, comprehensive element simulations are conducted to explore the effects of concentration, particle stiffness, and strain rate paths on the model. The proposed model's effectiveness is also validated against experimental data. Finally, a detailed comparison with the typical mu(I) rheology model and a state-equation-based phase transition model is conducted. Our analyses show that the developed model effectively captures strain rate path and particle stiffness through the collisional stress component, while concentration-dependent characteristics are captured through both frictional and collisional stress components. Through comparative analyses, we also found that both the state-equation-based and elastoplasticity-based models depict solid-like behavior and replicate the rheology of granular media in a fluid-like state, similar to the mu(I) model. However, they differ in implementing critical state theory: the state-equation-based model acts as a partial-range phase transition model, describing stress evolution from the critical state to the fluid-like state, while the proposed elastoplasticity-based model serves as a full-range phase transition model, covering stress evolution from the initial to the fluid-like state.

Debris flows are catastrophic mass movements with significant social and environmental consequences, particularly in the Western Himalayas. Understanding the rheological properties of debris flow material is crucial for accurately modeling their behavior and predicting their impacts. In this study, rheological parameters such as yield stress and viscosity were determined through extensive laboratory testing using a parallel plate setup in a rheometer. Reconstituted soil samples from the debris flow zone were prepared using an optimized sampling approach to vary the solid volume concentration and water content (w/c). Experimental results revealed non-Newtonian behavior for all tested compositions, which closely aligned with the Herschel-Bulkley rheological model. The Herschel-Bulkley parameters were subsequently used to calibrate a smooth particle hydrodynamics (SPH) model in the open-access DualSPHysics tool. The results showed that water content and silt concentration played a significant role in influencing the rheology, with finer particles exhibiting higher viscosity and shear stress compared to coarser particles. The SPH simulations effectively replicated the flow behavior observed during the Kotrupi debris flow event (2017), providing insights into flow dynamics, such as velocity and shear distribution. This integration of experimental rheology and numerical modeling advances our understanding of debris flow mechanics and highlights the importance of incorporating rheological calibration in predictive debris flow models.

Accurate continuum modelling of granular flows is essential for predicting geohazards such as flow-like landslides and debris flows. Achieving such precision necessitates both a robust constitutive model for granular media and a numerical solver capable of handling large deformations. In this work, a novel unified phase transition constitutive model for granular media is proposed that follows a generalized Maxwell framework. The stress is divided into an elastoplastic part and a viscous part. The former utilizes a critical-state-based elastoplasticity model, while the latter employs a strain acceleration-based mu(I) rheology model. Key characteristics such as nonlinear elasticity, nonlinear plastic hardening, stress dilatancy, and critical state concept are incorporated into the elastoplasticity model, and the non-Newtonian mu(I) rheology model considers strain rate and strain acceleration (i.e., a higher-order derivative of strain) to capture changes in accelerated and decelerated flow conditions. A series of element tests is simulated using the proposed unified phase transition model, demonstrating that the novel theory effectively describes the transition of granular media from solid-like to fluid-like states in a unified manner. The proposed unified model is then implemented within the material point method (MPM) framework to simulate 2D and 3D granular flows. The results show remarkable consistency with results from experiments and other numerical methods, demonstrating the model's accuracy in capturing solid-like behaviour during inception and deposition, as well as liquid-like behaviour during propagation.

Underground structures are subject to deterioration conditions in which water leakage occurs through cracks due to the long-term influence of soil and groundwater. Therefore, composite waterproofing sheets can play an important role in securing the leakage stability of structures by combining them with concrete structures. In this study, a total of eight composite waterproofing sheets were used according to the thickness of the compound and the properties of the material attached to the concrete, and the deformation characteristics at the bonding surface were identified through repeated tensile tests. Types A, B, and C, with a compound thickness of 1.35 to 1.85 mm and a single layer, had strong bonding performance, with a deformation rate of 0.5 to 2 x 10-4 and a DE/RE ratio of 0.3 to 1.3; tensile deformation progressed while maintaining integrity with the concrete at the bonding surface. Types D and E were viscoelastic and non-hardening compounds with a compound thickness of 1.35 to 3.5 mm, where the strain rate due to tensile deformation was the lowest, at 0.1 x 10-4 or less, and the DE/RE ratio was -5 to 3; therefore, when internal stress occurs, the high-viscosity compound absorbs it, and the material is judged to have low deformation characteristics. Types F, G, and H, which were 2 to 2.9 mm thick and had two layers using a core material, were found to have characteristics corresponding to tensile deformation, as the strain rate increased continuously from 0.2 to 0.5 x 10-4, and the DE/RE ratio increased up to 8 mm of tensile deformation.

Debris flows are destructive mass movements that pose multifaceted challenges with profound social and environmental implications in the Western Himalayas. For precise modeling and flow behavior prediction, it is essential to understand the rheological characteristics of debris flow material. In the current study, rheological characteristics like yield stress and viscosity were determined by a series of lab tests using a parallel plate setup in a rheometer. An optimized sampling approach created the reconstituted soil samples of finer particles to change the solid volume concentration and volumetric water content (w/c). Later, the feature importance of finer particles in debris flow rheology was determined using a machine learning regressor. Non-Newtonian behavior was shown by each composition and was similar to Herschel-Bulkley's rheological model. The eXtreme Gradient Boosting (XGBoost) regression model was developed for rheological parameters with robust model fitting with R2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${R}{2}$$\end{document} = 0.90 for yield stress and R2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${R}{2}$$\end{document} = 0.94 for viscosity. The model helped in understanding the sensitivity of rheological parameters with solid constitutents of debris flows. The findings showed that water content and silt concentration substantially impacted the debris flow's rheology. The yield stress was more dominated by silt followed by fine sand, whereas water content influenced the viscosity more than any solid concentration. The flow behavior was also affected by the distribution of grain sizes, with finer particles exhibiting higher viscosity and shear stress than coarser particles. These results enhance understanding of debris flow rheology and highlight the complex interplay between geohazards and sustainable development.

Establishing a permanent, self-sufficient habitat for humans on planetary bodies is critical for successful space exploration. In-situ resource utilisation (ISRU) of locally available resources offers the possibility of an energy-efficient and cost-effective approach. This paper considers the high-temperature processing of molten lunar regolith under conditions which represent the lunar environment, namely low gravity, low temperature, and negligible atmospheric pressure. The rheological properties of the low-titanium lunar mare regolith simulant JSC-1A are measured using concentric cylinder rheometry and these results are used to explore the influence of viscosity on processing operations involving the flow of molten regolith for fabricating construction components on the Moon surface. These include the delivery of molten regolith within an extrusion-based 3D printing technique and the ingress of molten regolith into porous structures. The energy and power required to establish and maintain sufficiently high temperatures for the regolith to remain in the liquid state are also considered and discussed in the context of lunar construction.

Utilizing casein in geotechnical engineering and construction can reduce global dairy waste. Variations in initial water content during sample preparation influence cation and OH ion availability, alkaline additive concentrations, casein binder function, and rheological properties of the casein solution. This study investigates the impact of initial water content and casein solution rheology on unconfined compressive strength in two soil types (coarse and fine) treated with casein, both in dry conditions and after water immersion. The study also assesses the long-term performance of casein-treated soil under bio-decomposition. Results suggest that increasing casein content, beyond the optimal ratio, can enhance strength by adjusting initial water concentration. Notably, calcium caseinate-treated soil shows improved water resistance, with wet strength reaching 833 kPa at 5% casein and 20% initial water content, due to reduced viscosity and better workability, resulting in a more rigid soil structure during preparation. We propose an empirical formula describing the influence of casein solution rheological characteristics on soil strength. Furthermore, artificial neural networks, developed from experimental data, predict casein-treated soil strength, highlighting the significance of initial water content and rheological parameters.

Soil contamination by organic and hazardous substances is a critical environmental issue, particularly in developing countries. This study investigates the limitations of double-layer theory for bentonite-organic contaminant interactions through experimental and numerical analysis. Using NaCl and KCl as salts and acetone, isopropyl alcohol, and glycerol as organic contaminants, the research explores the rheological properties of Na-bentonite dispersions. The double-layer theory, particularly Stern's model, has limitations in accurately representing the interaction between bentonite and organic contaminants. The research aims to validate the double-layer equations and investigate the impact of viscosity and cation hydrated radius on the rheological properties of Na-bentonite. The novelty lies in introducing a range of viscosities into the pore fluid to challenge existing double-layer equations. Numerical calculations based on double-layer theory were used to analyze the total interaction energy. The study found that without salt, bentonite showed similar rheological behavior in acetone and alcohol but higher yield stress in glycerol. NaCl up to 0.1 M increased yield stress, while 0.5 M reduced it. KCl had a more pronounced effect on rheological properties than NaCl, highlighting the importance of cation hydrated radius. In soil-organic mixtures, lower viscosity organic chemicals increased yield stress. Despite similar dielectric constants, acetone showed higher yield stress than glycerol at lower concentrations, but at higher concentrations, dielectric constant differences became dominant. The study confirms the limitations of double-layer theory in bentonite-organic contaminant interactions, particularly regarding pore fluid viscosity, though it remains reliable at high contaminant concentrations.