Abstract: Distributed widely in loess area, joints are the weak channel of loess and the dominant channel of water infiltration. At present, studies on the engineering characteristics, especially on the law of seepage through joints are inadequate. In this paper, the distribution and range of water infiltration in typical loess with single joint are analyzed by model test. According to the model test results, the equivalent saturated permeability coefficient of loess with typical joint width of 0.41 mm, 0.80 mm and 1.24 mm are obtained as 1.5×10^-4 cm/s, 1.67×10^-4 cm/s and 1.83×10^-4 cm/s, respectively, by combining unsaturated seepage theory and numerical analysis using SEEP/W. In addition, the influence of joints on the distribution of moisture field and the influence of the number and spacing of joints on the infiltration range are studied. Results revealed that joint has a great influence on the moisture field of loess site. The depth of humid zone increases remarkably with the growth of the number of joints. With the augment of joint spacing, the effect of joint spacing on humid zone depth gradually disappears. The width of humid zone is less affected by the spacing of joints.

Key words: loess joint, seepage, humid zone, model test, numerical simulation