Understanding slope stability is crucial for effective risk management and prevention of slides. Some deterministic approaches based on limit-equilibrium and numerical methods have been proposed for the assessment of the safety factor (SF) for a given soil slope. However, for risk analyses of slides of earth dams, a range of SFs is required due to uncertainties associated with soil strength properties as well as slope geometry. Recently, several studies have demonstrated the efficiency of artificial neural network (ANN) models in predicting the SF of natural and artificial slopes. Nevertheless, such techniques operate as black-box models, prioritizing predictive accuracy without suitable interpretability. Alternatively, multivariate polynomial regression (MVR) models offer a pragmatic interpretability strategy by combining the analysis of variance with a response surface methodology. This approach overcomes the difficulties associated with the interpretability of the black-box models, but results in limited accuracy when the relationship between independent and dependent variables is highly nonlinear. In this study, two models for a quick assessment of slope SF in earth dams are proposed considering the MVR and the ANN models. Initially, a synthetic dataset was generated considering different soil properties and slope geometries. Then, both models were evaluated and compared using unseen data. The results are also discussed from a geotechnical point of view, showing the impact of each input parameter on the assessment of the SF. Finally, the accuracy of both models was measured and compared using a real-case database. The obtained accuracy was 78% for the ANN model and 72% for the MVR one, demonstrating a great performance for both proposed models. The efficacy of the ANN model was also observed through its capacity to reduce false negatives (a stable prediction when it is not), resulting in a model more favorable to safety assessment.

This paper addresses the issue of crack expansion in adjacent buildings caused by foundation pit construction and develops a predictive model using the response surface method. Nine factors, including the distance between the foundation pit and the building, soil elastic modulus, and density, were selected as independent variables, with the crack propagation area as the dependent variable. An orthogonal test of 32 conditions was conducted, and crack propagation was analyzed using the FEM-XFEM model. Results indicate that soil elastic modulus, Poisson's ratio, and distance between the pit and building significantly impact crack propagation. A predictive model was developed through ridge regression and validated with additional test conditions. Single-factor analysis showed that elastic modulus and Poisson's ratio of the silty clay layer, elastic modulus of sandy soil, and pit distance have near-linear effects on crack propagation. In contrast, cohesion, density, and Poisson's ratio of sandy soil exhibited extremum points, with certain factors showing high sensitivity in specific ranges. This study provides theoretical guidance for mitigating crack propagation in adjacent buildings during excavation.

Rotary tillage knives, the most critical component of rotary tillage machinery, are extremely susceptible to bluntness and even breakage, affecting the tillage efficiency and performance of rotary tillage machines. Although drag reduction methods can mitigate the breakage of rotary knives to a certain extent, the breakage mechanism of rotary knives due to impacts and chiseling in the soil cutting process remains unclear. Taking the existing rotary tillage knife based on self-excited vibration as a prototype, a coupled DEM-MBD (discrete element method-multi-body dynamics) simulation model is established to analyze the three-directional resistance of the rotary tillage knife during soil cutting from a microscopic perspective. Moreover, a strength analysis is carried out for the rotary tillage knife body based on the simulation data, verifying the feasibility of the theory of selfexcited vibration for the reduction of resistance and damage of rotary tillage knives. However, the root of the rotary tiller blade is susceptible to fatigue failure due to its discontinuous geometric structure and the influence of cyclic loading. Accordingly, reinforcement bars are welded at the root of the self-excited vibration rotary cutter, and a strength analysis of the reinforcement bars of different sizes and structures is carried out through the response surface test. The Pareto front principle is also introduced to select the optimization parameters. The maximum deformation and maximum equivalent force of the optimized self-excited vibratory rotary cutter are reduced by 52.6 and 46.8 percentage points compared with those of the traditional rotary cutter and 11.1 and 23.1 percentage points compared with those of the self-excited vibratory rotary cutter structure before optimization, respectively. Results of the real-machine test show that the average torque reduction rate of the optimized self-excited vibratory rotary cutter is 12.91% compared with that of the traditional rotary cutter under the optimal working speed. The tillage depth stability of the rotary tiller equipped with a self-excited vibration rotary cutter is 95.78%, and the soil breakage rate is 71.39%, thereby meeting the operating requirements. The results of this study have practical significance for improving the operating life of rotary tiller knives and a high reference value for the application of self-excited vibration theory in rotary tillage operation.

For construction quality control, the compaction delay referred to as mellowing time (MT) is crucial for achieving the desired outcomes of the chemical soil stabilization process in the field. In the current study, fly ash-based geopolymer (GFA) is used as a chemical stabilizer for expansive clay because of its significance in resource utilization and waste repurposing for soil stabilization through an enhanced process. The MT-influenced macroscopic physicomechanical properties and microstructural and mineralogical properties of expansive clay treated with varying GFA and curing period (CP) were investigated. The significant amelioration of strength and compression properties is observed through the unconfined compression test, California bearing ratio test, and one-dimensional (1D) consolidation test with an increase in GFA content and CP. This improvement is caused by the formation of cementitious [(N, C)-A-S-H] compounds as confirmed by SEM, EDAX, and XRD analyses. Meanwhile, as the MT increases, a decline in both the strength and compression characteristics of the GFA-treated specimens is observed. However, these specimens exhibit a reversal in deformability and brittleness with an increase in MT, which can be attributed to the development of a porous aggregated soil structure resulting from initial hydration before densification. In addition, a generalized mathematical modeling framework was established based on three-dimensional (3D) response surface modeling to quantify the MT-influenced strength and brittleness-related characteristics using MT, GFA, and CP as predictors. The established mathematical framework showed generality and reasonable accuracy in the prediction based on the experimental data. This article outlines the implications for practitioners and researchers of using GFA for the stabilization of expansive clay considering MT-influenced mechanical characteristics in the field.

Biodegradable plastic is the preferred alternative to traditional plastic products due to its high degradability, decreased dependence on fossil sources, and decreased global pollution according to the accumulation of traditional plastic. In the current study, the optimization of biodegradable plastic synthesis was studied using biomass reinforcement materials. The reinforcement material is cellulose extracted from sawdust to prepare biodegradable plastic using the casting method. Response surface methodology using Box-Behnken Design is used to optimize the main parameters affecting the tensile strength and elongation at the break of the biodegradable plastic. These parameters are cellulose fiber addition, acetic acid addition, and the mass ratio of glycerol to starch. The maximum tensile strength and elongation were obtained at 4.45 MPa and 5.24%, respectively, using 5% cellulose fiber addition and 11.24% acetic acid addition with a 0.266 w/w glycerol to starch mass ratio. Various analyses were performed on the produced biodegradable plastic, including FTIR, SEM, and thermal stability. The biodegradability of the produced biodegradable plastic after immersing the soil for 10 days was about 90% higher than the traditional plastics. The produced biodegradable plastic has a moisture content of 4.41%, water absorption of 81.5%, water solubility of 24.6%, and alcohol solubility of 0%. According to these properties, the produced biodegradable plastic can be used in different industries as a good alternative to traditional plastics.

In order to accurately model the machine-lunar soil simulant interaction, this study combined physical and simulation experiments to calibrate the discrete element simulation parameters of the JLU-H lunar highland simulant. First, the intrinsic parameters and the true angle of repose of the JLU-H were determined through physical tests to provide data for subsequent simulation tests. A Plackett-Burman test was designed to identify and select the parameters that have a significant effect on the angle of repose. The range of values of the significant parameters was then optimized using the steepest climb test. The Box-Behnken test was then utilized to calibrate and obtain the optimal parameter combinations. Finally, a validation test of the angle of repose was conducted using the calibrated DEM parameters. The relative error between the simulation results and the test results was 1.54 %. Then further straight shear tests were conducted to verify the accuracy and validity of the DEM parameters. The results show that the calibrated parameters can provide a reference for the selection of discrete element simulation parameters for lunar soil simulant and the design and optimization of drilling and excavation machinery for lunar exploration. (c) 2024 COSPAR. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

In light of the problems of large operation resistance and small soil fragmentation during the harvesting operations of existing cassava harvesters, a long- and short-toothed digging shovel was designed. A virtual simulation soil trough model of cassava ridge soil particles was established using the discrete element method, and the Hertz-Mindlin with JKR contact model was employed to simulate the operation quality of the long- and shorttoothed digging shovel and the original digging shovel. In the movement and force analysis of the digging shovel, the angle of entry, the advance speed of the machine, and the height of the digging adjustment were the test factors. The response surface test was conducted on the digging rate and the damaged cassava rate. The results of the experimental field trial showed that the average digging rate of harvested cassava increased by 2.56%, and the average rate of damaged harvested cassava decreased by 1.54%, compared with the original digging shovel. The digging operation process was stable and met the requirements of cassava harvesting field operations. The results of this study may inform future studies on the design and improvement of a cassava harvester.

Injection-induced seismicity has been a focus of industry for decades as it poses great challenges to the associated risk mitigation and hazard assessment. The response surface methodology is integrated into the geo-mechanical model to analyze the effects of multiple factors on induced seismicity during the post shut-in period. We investigate the roles of poroelastic stress and pore pressure diffusion and examine the differences in the controlling mechanism between fault damage zones and the fault core. A sensitivity analysis is conducted to rank the selected factors, followed by a Box-Behnken design to form response surfaces and formulate prediction models for the Coulomb stress and its components. Reservoir properties significantly affect the potentials of induced seismicity in the fault by changing pore pressure diffusion, which can be influenced by other factors to varying degrees. Coulomb stress is greater in pressurized damage zones than in fault cores, and the seismicity rate exhibits a consistent variation. Poroelastic stress plays a similar role to pore pressure diffusion in the stability of the fault within the pressurized damage zones. However, pore pressure diffusion dominates in the fault core due to the low rigidity, which limits the accumulation of elastic energy caused by poroelastic coupling. The slip along the fault core is a critical issue to consider. The potential for induced seismicity is reduced in the right damage zones as the pore pressure diffusion is blocked by the low-permeability fault core. However, poroelastic stressing still occurs, and in deep basements, the poroelastic effect is dominant even without a direct increase in pore pressure. The findings in this study reveal the fundamental mechanisms behind injection-induced seismicity and provide guidance for optimizing injection schemes in specific situations. (c) 2024 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. 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/).

This study utilizes polymers based on coal gangue and blast furnace slag to solidify engineering slurry with high silt content. Response surface methodology was employed to investigate the effects of polymer composition, alkali activator modulus, and coal gangue calcination temperature on the unconfined compressive strength of stabilized soil. Additionally, the study comprehensively characterized the thermal stability, pore structure, molecular bonds, mineral composition, and micro-morphology of the stabilized soils, and explored the mechanisms governing their strength development. The results demonstrate that the highest strength of stabilized soils is achieved with a slag to coal gangue ratio of 2.5:7.5, a water glass modulus of 1.2, and a coal gangue calcination temperature of 750 degrees C. Formation of calcium-aluminum-silicate-hydrate (C-A-S-H) and sodium-aluminum-silicate-hydrate (N-A-S-H) contributes significantly to the strength development. The presence of slag promotes early strength through C-A-S-H formation, while coal gangue facilitates N-A-S-H formation, supporting later-stage strength development by filling micropores. By applying alkali-activated calcined coal gangue-slag based cementitious materials to solidify engineering slurry, this research not only elucidates the mechanism of alkaliactivated calcined coal gangue-granulated blast furnace slag in slurry solidification but also promotes the utilization of industrial solid waste, providing new insights for environmental protection and resource recovery.

As marine-dredged mud and waste steel slag in coastal port cities continue to soar, the traditional treatment method of land stockpiling has caused ecological problems. Thus, it is necessary to find a large-scale resource-comprehensive utilization method for dredged mud and waste steel slag. This study uses waste steel slag and composite solidifying agents (cement, lime, fly ash) to physically and chemically improve marine-dredged mud. The physical improvement effect of the particle size and dosage of waste steel slag was studied by the shear strength test under the effect of freeze-thaw cycle. Then, based on the Box-Behnken design of the response surface method, the interaction effects of the solidifying agent components on the unconfined compressive strength were studied. Then, the water stability under dry-wet cycles and a microscopic mechanism were analyzed by XRD and SEM tests. The results show that the waste steel slag with a dosage of 30% and a particle size of 1.18 similar to 2.36 mm has the best improvement. The interaction between cement and lime and lime and fly ash has a significant effect on the linear effect and surface effect of 7d unconfined compressive strength, and the strength increases first and then decreases with the increase in its dosage. For the 14d unconfined compressive strength, only the interaction between cement and lime is still significant. The unconfined compressive strength prediction model is established to optimize the mix ratio of the composite solidifying agent. In the water stability, the water stability coefficients of the 7d and 14d tests are 0.68 and 0.95, respectively, and the volume and mass loss rates are all below 1.5%, showing a good performance in dry-wet resistance and durability. Microscopic mechanism analysis shows that waste steel slag provides an 'anchoring surface' as a skeleton, which improves the pore structure of dredged mud, and the hydration products generated by the solidifying agent play a role in filling and cementation. The results of the study can provide an experimental and technical basis for the resource engineering of marine-dredged mud and waste steel slag, helping the construction of green low-carbon and resource-saving ports.