Abstract
Red-bed soft rock easily softens and disintegrates when it comes into contact with water, which is the main factor restricting the application of soft rock as an engineering filler. Therefore, research on the influence of seawater on soft rock softening has great significance for the application of soft rock in marine engineering. To examine the softening mechanism of soft rock under seawater conditions, two kinds of soft rock softening experiments, as well as ion inhibition tests of soft rock softening, were performed under seawater and pure water conditions, and the results were compared. The variation in the soft rock composition, the deformation and failure characteristics of soft rock under the influence of sea water, and the variation in main cations in the softening process of soft rock are examined successively; the influences of different ions on soft rock softening are further analysed. Based on the analyses, the softening mechanism and control method of soft rock under sea water conditions are expounded. The study showed that soft rock softening was inhibited by seawater, which decreased the softening degree of soft rock. The main cations in seawater had an inhibitory effect on soft rock softening, and the order of inhibition was Ca2+ > Mg2+ > Na+. According to the inhibitory effect of ions on soft rock softening, we propose that seawater or calcium salt should be added to reduce the softening of soft rock in soft rock engineering and improve the mechanical strength of soft rock; in addition, soft rock can be considered a raw material in marine engineering. The experimental results have great significance for studies of the disintegration mechanism and inhibitory rules of soft rock under the influence of seawater and provide a theoretical basis for the application of soft rock in marine engineering, such as in artificial reef engineering and coastal dike engineering.
Highlights
In recent years, with the construction of man-made islands and reefs, maritime airports, undersea tunnels, undersea military bases and other marine projects, marine engineering has entered an era of great advancements
The concentrations of the four main cations in seawater are in the order of Na+ > Mg2+ > Ca2+ > K+, and so MgCl2, CaCl2 and NaCl are selected as the dissolved salts in the experiments, and K+ is not considered in the experiments
It can be deduced that the soft rock softening rate is higher, the water-rock interactions are stronger, and the degree of disintegration is higher in pure water
Summary
With the construction of man-made islands and reefs, maritime airports, undersea tunnels, undersea military bases and other marine projects, marine engineering has entered an era of great advancements. In addition to indoor modification tests of soft rock, scholars have performed road use research on soft rock [25,26,27,28,29] These studies provide a solid theoretical basis for the control of soft rock softening. This paper takes sandy mudstone as the research object, and saturated tests of soft rock under seawater conditions are performed to study the evolution of the soft rock strength under the influence of seawater and the variation in the main cations in solution during the softening process of soft rock; in addition, the characteristics of composition change, deformation and failure of the soft rock are examined. The study provides experimental and theoretical bases for the study of the effective utilization of soft rock in marine engineering
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
