A Tale of Two Continents: Factors Influencing Students to Major in Mathematics

Students consider the selection of their college major as one of the critical decisions in their life. Literature suggests that influencing factors can differ based on the academic discipline, student status (freshmen, declared, etc.), and geography. We select two countries, the United States and Sri Lanka, with contrasting education systems and study the factors which may have influenced students to become mathematics majors. We consider the effect of ten influencing factors, which form three clusters, namely, “Career-Related”, “Math-Related”, and “Other”. The study first reveals that the factors and clusters significantly affect student decisions in the two countries. One of the critical conclusions of the study is how the “MathRelated” cluster influences students’ decisions significantly more than the other two clusters. We also look at the difference in the impact of specific influencing factors on the two populations and find that factors related to the nature of mathematics influence US students more than Sri Lankan students. The study’s conclusions should benefit teachers and recruiters when guiding future math majors

Shear behaviour of rock joints with unsaturated infill

Behaviour of soil-infilled rock joints has significant importance with respect to the strength of fractured rock mass. The presence of even a small amount of fine-grained infill material within a joint can reduce its shear strength considerably, depending on the degree of saturation of infill. Therefore, it is crucial to examine how the infill material can adversely affect the joint shear strength. Previous studies of infilled joints have mainly been focused on idealised regular joint patterns owing to the simplicity and reproducibility in laboratory testing. Current literature on infilled rock joints has also neglected the effect of the degree of saturation of infill on the shear behaviour. In most instances, fully saturated infill has been used or assumed, and the contribution of matric suction on the shear strength of joints having unsaturated infill has not been studied. In this study, a series of triaxial tests on natural joint profiles having joint roughness coefficient (JRC) of 10-12 is carried out at constant moisture content. A semi-empirical model is proposed and validated on the basis of laboratory data

Shear strength of rock joints influenced by compacted infill

Discontinuities such as fault planes, joints and bedding planes in a rock mass may be filled with different types of fine-grained material that are either transported or accumulated as gouge due to weathering or joint shearing. Previous laboratory studies have mainly examined the role of saturated infill that exhibits the minimum shear strength. However, in practice, the infill materials are often partially saturated generating matric suction within the joint that can contribute to increased shear strength. To the authors' knowledge this is the first study to examine the influence of compacted (unsaturated) infill on the joint shear strength. A series of laboratory triaxial tests on idealised model joints and imprinted natural joint profiles was carried out, with constant water contents of the infill being maintained. From the laboratory results, it is observed that the peak shear strength of infilled joints increased with the decrease of degree of saturation from 85% to 35% for both idealised joints and replicated natural joints. Based on the laboratory observations an empirical model for describing the infilled joint shear strength was developed