shear stress

pore water pressure

direct bearing on effective normal stress because it can add or subtract to it

friction

loose packed with smooth surfaces slide easier past each other dense packed with rough surface have higher resitance to shear

shear strength

properties of matter that resist the stresses generated by gravitational force

coulomb equation for shear stress

s = c + ((delta n +- water pore pressure)* tan phi)

soil shear strength

saturated soil - fricitional strength reduced dry soil - medium moist - friction at max

effective normal stress

stress exerted at the solid to solid contacts across the shear surface delta n

coefficient of plane sliding friction

tan phi

shear strain

change of shape or volume produced by a stress

shear stress

body deforms by one part sliding over the other

normal stress

capacity to hold material together increasing the internal resistance to shear acts perpendicular to shear surface two elements: effective normal stress and pore water pressure

cohesion

caused by chemical cementation of rock and soil particles and electrostatic and electromagnetic forces