Based on the static-friction model for solid-liquid-vapor contact line suggested by Adam and Jessop,one can calculate surface-tension coefficient of solids from the data of wetting angles, but the results depend on the friction condition adopted. Using the data reported on stainless steel and polypropylene samples as examples, we have compared the surface-tension coefficients given by the Mises yield condition and Amonton's friction law. It is found that only the latter pos sesses always the Wenzel behavior which claims an increase of surface-tension co efficient with surface roughness, as well as total wetting condition, namely rec eding angle vanishes when the difference of solid-liquid and solid-vapor coeffic ients equals that of liquid-vapor. This shows that the Amonton's law seems to be more reasonable for describing the static friction of contact line.
We report that when the density at the centre of a cohesionless granular pile is slightly smaller than the density at its sides, such that the elastic strength at the centre is evidently smaller than the strength at the sides, the pressure distribution under the pile will show a dip at the centre. For the conical (or w edge-shaped) piles formed by slowly pouring grains from a point (or a line), the small density variation may be due to the phenomenon that the pile is slightly tapped by the down-rolling grains along the pile surfaces. The computation shows that the observed pressure distribution can be well reproduced by the elastic t heory with a spatial-varying bulk modulus.
This paper shows that for a static cohesionless granular material simply averaging in space the strains inside grains does not result in its macroscopic strain , so the fields of displacement vector and strain tensor do not have the propert y of coarse-graining. However this gives no disturbance to the validity of the n otions of strain and elasticity for the granular material because they are based on the equilibrium thermodynamics.
Taking Maoyu Mountain Tunnel on the Lanzhou-Chongqing Railway as the object, this paper measures the surrounding rock pressure, initial support stress and other parameters in the tunnel of the pilot heading and space reservation, two popular methods for the stress release of high geo-stress soft rock tunnels. Then, the measured parameters of the two methods were compared and analyzed, aiming to select the stress release method suitable for the target tunnel. The comparative analysis shows that the maximum stress on the steel frame in initial support of pilot heading is 3.4 times that on the steel frame in initial support of space reservation, reaching the level of 340MPa. To release the stress of the said tunnel, it is recommended to reserve a large space (50cm) and add a flexible support net to deform with the surrounding rock. The flexible support net can withstand large deformation stress, thus reducing the stress on the initial support and that on the secondary lining. The research results show that the space reservation is an easy, efficient and economical way to release geo-stress before excavation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.