The large amount of slag generated during the construction of earth pressure balance shield (EPBS) not only incurs significant disposal costs, but also exacerbates environmental pollution. To improve the utilization of the shield slag, silty clay with additive is proposed as a slag conditioner instead of bentonite. Firstly, various macroscopic properties of the bentonite and silty clay slurries are tested. Subsequently, the relationships between the macroscopic properties of the silty clay slurries containing additives and the modification mechanism are evaluated at microscopic, mesoscopic, and macroscopic scales by using infrared spectroscopy (IR), scanning electron microscope (SEM), and Zeta potential tests, respectively. Based on these tests, reasons for variations in modification effects of different slurries are identified. The results show that addition of 3 % sodium carbonate to the silty clay can effectively improve the rheological properties of the slurry. The modification mechanism of sodium carbonate involves the formation of hydrogen bonds between water molecules and inner surface hydroxyl groups within the lattice layer of kaolinite. This process significantly enhances the rheological properties of the silty clay slurry. Furthermore, sodium carbonate alters the contact relationships between the silty clay particles, which increases viscosity and reduces permeability of the slurry. Finally, sodium carbonate increases thickness of the electrical double layer of the silty clay particles. This allows the particles to bind more water molecules, therefore improving slurry-making capacity of the silty clay. This paper presents an innovative multiscale analysis of the modification process of silty clay. The substitution of recycled silty clay for bentonite as a slag conditioner not only substantially reduces the cost of purchasing materials, but also considerably decreases the expenses associated with transportation and disposal of the soil discharged by EPBS.

The silt seabed can undergo liquefaction under wave action, resulting in the liquefied silt seabed exhibiting nonNewtonian fluid characteristics and fluctuating in phase with the overlying waves. The fluctuation of the liquefied silt seabed can impose periodic forces on the buried pipelines, posing a significant threat to their safety. This study achieves the measurement of the non-Newtonian fluid rheological properties of wave-induced liquefied silt, through the improvement of the falling-ball method. The improved falling-ball method enables in situ measurement of the rheological properties of liquefied silt in fluctuation state. This method is applied in two wave flume experiments to investigate the effects of wave intensity and the liquefaction process on the rheological properties of liquefied silt. Building on this foundation, a computational fluid dynamics (CFD) numerical model is developed to simulate the wave-liquefied silt interaction, utilizing the rheological properties of the liquefied silt obtained from experimental measurement. The model is used to evaluate the fluctuation velocity of the liquefied silt under field conditions and its forces acting on buried pipelines. The research findings provide foundational data for more accurate simulations of the movement of wave-induced liquefied silt and its effects on structures.

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.

Lunar soil-based polymers, created using lunar soil as a precursor combined with highly automated 3D printing construction methods, hold great potential for lunar base construction. However, technical challenges such as ambiguities in characterizing rheological behavior and difficulties in regulation limit their 3D printing workability. To address these issues, the applicability of the Bingham model, Herschel-Bulkley (H-B) model, and a modified Bingham model to TJ-1 simulated lunar soil-based polymer was investigated by analyzing the fluidity variation. The effects of the solid-liquid ratio, Ca(OH)2, and Hydroxypropyl Methyl Cellulose ether (HPMC) on the 3D printing performance of the simulated lunar soil-based polymer were explored through one-way tests and standard deviation analysis. The results show that the modified Bingham model more accurately describes the rheological properties of TJ-1 simulated lunar soil-based polymer. HPMC proved to be an effective thixotropic agent for adjusting the 3D printing performance of the polymer. The yield stress and plastic viscosity of the polymer doped with 0.15 % HPMC were 3.577 Pa and 0.733 Pa s, respectively, meeting the requirements for printability. The yield stress and plastic viscosity of the simulated lunar soil polymers ranged from 1.84 to 3.58 Pa and 0.23-0.73 Pa s, respectively. Moreover, the compressive and flexural strengths of the simulated lunar soil polymers were significantly improved by adding Ca(OH)2. The optimal ratios for 3Dprinted simulated lunar soil polymers are a water-cement ratio of 0.30, 10 % NaOH, 8 % Na2SiO3, 6 % Ca(OH)2, and 0.10 % HPMC. Under these conditions, the 28-day compressive strength and flexural strength were 19.5 MPa and 6.9 MPa, respectively, meeting the strength standards of ordinary sintered bricks.The research results could provide a theoretical basis for the subsequent optimization of the simulated lunar soil base polymer mixing ratios for 3D printing.

Studying the rheological properties of deep-sea shallow sediments can provide basic mechanical characteristics for designing deep-sea mining vehicles driving on the soft seabed, providing anchoring stability of semi-submersible mining platforms, and assessing submarine landslide hazards. Shallow sediment column samples from the Western Pacific mining area were obtained, and their rheological properties were studied. A series of rheological tests was conducted under different conditions using an RST rheometer. In addition, conventional physical property, mineral composition, and microstructure analyses were conducted. The results showed that shallow sediments have a high liquid limit and plasticity, with flocculent and honeycomb-like flaky structures as the main microstructure types. The rheological properties exhibited typical non-Newtonian fluid characteristics with yield stress and shear-thinning phenomena during the shearing process. In contrast to previous studies on deep-sea soft soil sediments, a remarkable long-range shear-softening stage, called the thixotropic fluid stage, was discovered in the overall rheological curve. A four-stage model is proposed for the transition mechanism of deep-sea shallow sediments from the solid to liquid-solid, solid-liquid transition, thixotropic fluid, and stable fluid stages. The mechanism of the newly added thixotropic fluid stage was quantitatively analyzed using a modified Cross rheological model, and this stage was inferred from the perspective of mineralogy and microstructure. The results of this study can be useful for improving the operational safety and work efficiency of submarine operation equipment for deep-sea mining in the Western Pacific Ocean. (c) 2025 Japanese Geotechnical Society. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).

The enzyme-induced calcium carbonate precipitation (EICP) method has been utilized for curing low-permeability clay by directly mixing the reaction solution with soil. The added reaction solution quantity is limited by the optimal water content, producing insufficient calcium carbonate. Herein, the high-activity urease and high-concentration cementation solution efficacy in treating dispersive soils was evaluated. Phase transitions and structural modifications in EICP-cured soils were investigated through oscillatory amplitude scanning. The soil gradation influence on the EICP treatment effectiveness was assessed. The fluidized EICP-cured soil cementation and rupture mechanisms were investigated by viscosity measurements, electron microscopy, and zeta potential evaluations. A 3 M cementation solution, coupled with 500g/L of soybean urease, significantly enhanced the soil shear resistance, increasing it by 339% to 1807%. The EICP-cured soil gradually transitioned from a fluid to a paste and eventually to a solid within 168 h. High-clay-particle-content soils exhibited pronounced increases in shear resistance after EICP treatment. Under dynamic loading, three shear crack types emerged in EICP-cured soils, emphasizing the importance of soybean protein viscosity and calcium carbonate crystal filling-bonding capability in enhancing soil structural stability. The fluid solidification effectiveness in treating fine-grained soils utilizing EICP was validated through erosion trenches in fluid-solidified check dams, validating its potential.

Solid-fluidization transition-induced flow-like events pose significant threats to both ecological systems and human society. This geophysical phenomenon undergoes a continuous and catastrophic solid-fluidization-solid retransition, which often leads to severe disasters. A series of flume and rheological tests were conducted to explore the continuous solid-fluidization-solid retransition mechanism of sedimentary loess. The results showed that the flow distance after phase retransition increased by 39.5% compared with the first flowslip distance. With increasing rainfall intensity, the moisture content during phase transition tended to decrease while the time required for reactivation lengthened. Rheological analyses revealed that the reduction and recovery of storage modulus exhibited by thixotropy is a crucial mechanism in the phase retransition of soil, and they have significant time-concentration dependence. A higher soil water content leads to a longer structural recovery time and stronger thixotropy, which agrees well with the results of flume tests. Our experimental data NSav and NBag showed a positive power-law relationship and had similar fitting coefficients to the field case data, indicating that our experimental results have successfully captured the kinematic and rheological characteristics of real mudflow events. This study suggests that thixotropy can be used to interpret complex phase retransition processes in mudflow and can also help to explain the hypermobility and reactivation of many large geophysical processes, such as pyroclastic flows.

This paper presents a new design numerical tool for geosynthetic-reinforced soil embankments, used to mitigate rockfall risk in scenarios of large volumes, energies, and multiple block failures. The model can simulate both local block penetration into the uphill embankment face and extrusion mechanism frequently affecting the downhill face. The new model is based on an existing elastic-visco-plastic model, originally developed to simulate impacts of blocks on homogeneous granular strata. The model has been enhanced and modified by incorporating a plastic mechanism, accounting for the extrusion process potentially occurring within the embankment body. The model is initially described and then validated using available in situ real-scale test data; finally, the results of a parametric study, examining the influence of the main controlling parameters and the applicability of the tool for pre-design purposes, are illustrated.

Rubber-based intercropping is a recommended practice due to its ecological and economic benefits. Understanding the implications of ecophysiological changes in intercropping farms on the production and technological properties of Hevea rubber is still necessary. This study investigated the effects of seasonal changes in the leaf area index (LAI) and soil moisture content (SMC) of rubber-based intercropping farms (RBIFs) on the latex biochemical composition, yield, and technological properties of Hevea rubber. Three RBIFs: rubber-bamboo (RB); rubber-melinjo (RM); rubber-coffee (RC), and one rubber monocropping farm (RR) were selected in a village in southern Thailand. Data were collected from September to December 2020 (S1), January to April 2021 (S2), and May to August 2021 (S3). Over the study period, RB, RM, and RC exhibited significantly high LAI values of 1.2, 1.05, and 0.99, respectively, whereas RR had a low LAI of 0.79. The increasing SMC with soil depths was pronounced in all RBIFs. RB and RM expressed less physiological stress and delivered latex yield, which was on average 40% higher than that of RR. With higher molecular weight distributions, their rheological properties were comparable to those of RR. However, the latex Mg content of RB and RM significantly increased to 660 and 742 mg/kg, respectively, in S2. Their dry rubbers had an ash content of more than 0.6% in S3.

Mudflows are natural phenomena starting from landslides and presenting high impact when they occur. They generate great catastrophes in their path because most of the time there is no indication prior to the failure that triggers them. Understanding how mud is transported is of great importance in infrastructure projects that coincide with hillside areas due to the high risk of occurrence of this phenomenon by cause of the high slopes, which can involve great risks and produce disasters that involve great costs. This work presents the evaluation of mudflows, from the implementation of a laboratory scale experiment in a consistometer with its calibration and validation from numerical models to estimate rheological parameters of the material. Tests were also carried out in an open channel in the laboratory, based on the data previously obtained considering the behavior of the material as a both Newtonian fluid and non-Newtonian fluid. The experiment considered a channel with dimensions of 3 m long, 0.5 m high and 0.7 m wide with slope control, and a mud composition of silty material with 60% moisture. The tests were conducted with slopes of 5%, 10%, 15% and 20%. The numerical models were carried out in ANSYS FLUENT software. In addition, the calibration data of the numerical model were used for a real case study, simulating the slip flow occurred in Yangbaodi, in the southeast of China, occurred on September 18, 2002. The results of the numerical models were compared with the experimental results and show that these have a great capacity to reproduce what is observed in the laboratory when the material is considered as a non-Newtonian fluid. The model reproduced in an appropriate way the movement of the flow at laboratory scale, and for the aforementioned case study, some differences in the final length of deposition were noticed, achieving interesting results that lead the use of the calibrated model towards the estimation of risks due to the mudflow occurrence.