Numerical analysis of seepage–deformation in unsaturated soils

A coupled elastic–plastic finite element analysis based on simplified consolidation theory for unsaturated soils is used to investigate the coupling processes of water infiltration and deformation. By introducing a reduced suction and an elastic–plastic constitutive equation for the soil skeleton, the simplified consolidation theory for unsaturated soils is incorporated into an in-house finite element code. Using the proposed numerical method, the generation of pore water pressure and development of deformation can be simulated under evaporation or rainfall infiltration conditions. Through a parametric study and comparison with the test results, the proposed method is found to describe well the characteristics during water evaporation/infiltration into unsaturated soils. Finally, an unsaturated soil slope with water infiltration is analyzed in detail to investigate the development of the displacement and generation of pore water pressure

Post-electrospinning crosslinking of guar/polyvinyl alcohol membrane

College of Material and Textile Engineering, Jiaxing University, Jiaxing, China The present study reports post-electrospinning crosslinking of guar/polyvinyl alcohol (PVA)/citric acid nanofiber membranes by heat treatment. Porous, interconnected nonwoven nanofiber membranes (average diameter 194±23 nm) were electrospun from a homogeneous blend of 1wt% guar gum and 8wt% polyvinyl alcohol solution (3:7 weight ratio) containing 5 wt% (by the total weight of the solution) citric acid. The electrospun nanofiber membranes were then cured at 140 oC for 2 h. The crosslinked nanofiber membranes were insoluble in water, while the non-crosslinked membranes dissolved instantaneously. FT-IR spectrum investigates that crosslinking of guar/PVA occurred through esterfication reaction during heat treatment

Composition dependence of spin-orbit torques in PtRh/ferromagnet heterostructures

10.1063/5.0046766APL Materials944110

Does e-shopping for intangible services attenuate the effect of spatial attributes on travel distance and duration?

E-shopping for intangible services (e.g., eating out services, hairdressing, and visits to movie theatres) refers to searching and paying for services online, but it requires e-shoppers to travel to use these services. In theory, e-shoppers’ search space via the internet is less constrained by spatial attributes. As a result, spatial attributes may barely affect the distance and duration of trips resulting from e-shopping for intangible services. The present study used data from 714 valid face-to-face interviews in Beijing, China, to verify this hypothesis. The results showed that e-shoppers were likely to travel farther after purchasing intangible services online. The effect of spatial attributes on the distance of a single trip was largely attenuated due to online purchases of these services, and the effect on the duration was correspondingly weaker to a limited extent. Therefore, spatial interventions aiming to moderate travel distances and durations may not be as effective in the age of online shopping

Deformation Monitoring of Geomechanical Model Test and Its Application in Overall Stability Analysis of a High Arch Dam

Geomechanical model testing is an important method for studying the overall stability of high arch dams. The main task of a geomechanical model test is deformation monitoring. Currently, many types of deformation instruments are used for deformation monitoring of dam models, which provide valuable information on the deformation characteristics of the prototype dams. However, further investigation is required for assessing the overall stability of high arch dams through analyzing deformation monitoring data. First, a relationship for assessing the stability of dams is established based on the comprehensive model test method. Second, a stability evaluation system is presented based on the deformation monitoring data, together with the relationships between the deformation and overloading coefficient. Finally, the comprehensive model test method is applied to study the overall stability of the Jinping-I high arch dam. A three-dimensional destructive test of the geomechanical model dam is conducted under reinforced foundation conditions. The deformation characteristics and failure mechanisms of the dam abutments and foundation were investigated. The test results indicate that the stability safety factors of the dam abutments and foundation range from 5.2 to 6.0. These research results provide an important scientific insight into the design, construction, and operation stages of this project

Influence of inorganic and organic salts on the hydration mechanism of montmorillonite based on molecular simulation

Abstract The molecular dynamics method is used to further reveal, from the molecular point of view, the mechanisms of salt inhibiting the hydration of Na-MMT. The interaction between water molecules, salt molecules, and montmorillonite are calculated by establishing the adsorption models. According to the simulation results, the adsorption conformation, interlayer concentration distribution, self-diffusion coefficient, ion hydration parameters, and other data are compared and analyzed. The simulation results show that the volume and basal spacing increase in a stepwise manner with the increase of water content, and water molecules have different hydration mechanisms. The addition of salt will enhance the hydration properties of compensating cations of montmorillonite and affect the mobility of particles. The addition of inorganic salts mainly reduces the adsorption tightness between water molecules and crystal surfaces, thereby reducing the thickness of water molecules layer, while the organic salts can better inhibit migration by controlling interlayer water molecules. The results of molecular dynamics simulations reveal the microscopic distribution of particles and the influence mechanism when the swelling properties of montmorillonite are modified by chemical reagents

Intelligent Explorations of Occupational Disease Prevention and Control in Coal Mine

Coal enterprises in high yield and high efficiency at the same time accompanied by a large number of occupational disease personnel, in order to continuously improve the operating environment of coal mining enterprises in each operation point, reduce occupational disease hazards, reduce the incidence of occupational diseases, to ensure the health and personal safety of operators, in recent years in China’s coal industry occupational disease incidence and occupational health management department changes on the basis of the basis of intelligent mine construction theory and technology, combined with the production and distribution of occupational disease hazard factors in various coal mine work sites, Through the comprehensive use of optimization of the equipment start-up process, the real-time monitoring technology of occupational disease hazard factors and the linkage of key equipment, the excavation of the long pressure short pumping system of the working surface, the establishment of a centralized control room, the exploration of the use of positive pressure fully enclosed helmets, active sound reduction technology, noise reduction headphones and other intelligent technologies and means, from the source control, process elimination, terminal control of the three dimensions of dust concentration and noise value to the coal mine safety regulations limit value, thereby improving the operating environment, reducing the incidence of occupational diseases, Maximize the health of operators throughout their careers and help coal companies achieve sustainable development