A new model characterized as describing increase in pore-water pressure in fully saturated fine sand specimens

through experimental studies include a resonant column test

a series of drained/undrained multistage strain-controlled cyclic triaxial（MSCCTX） tests and drained/undrained single-stage strain-controlled cyclic triaxial（SSCCTX） tests on a schistous fine sand named"Nanjing sand"

is development in this paper. It follows the theoretical framework of Martin’s semi-theoretical model presented by Martin and Byrne. The increase in pore pressure is caused by the change in volumetric stra

in under cyclic shear load. Thus

this proposed model is controlled by strain. Based on the drained SSCCTX tests

by introducing the concept of volumetric threshold shear strain(γ

tv

) and a representative volumetric strain in 15 cycles

volumetric strains can be normalized by cyclic shear strains

and then a three-parameter incremental shear-volume strain coupling equation is proposed. Combining experimental results of drained and undrained SSCCTX tests

the relationship between volumetric strain and pore pressure ratio is established. Thus

a new pore water pressure increment model coupling new shear strain-volumetric strain is also established considering volumetric strain increment and elastic rebound modulus. Finally

this new pore pressure model is validated

and the predicted pore pressure ratios in the model match well with those obtained from tests including an undrained SSCCTX test and a stress-controlled cyclic test.