Meso and micro pore structure test of Jingyang shallow loess

Rainfall and irrigation are the most common driving forces of geological disasters in loess areas. Generally, the infiltration depth is shallow and mainly controlled by microchannels. The pore structure has a significant influence on the seepage characteristics. Aiming to study the distribution of pore structure in shallow loess, this study analyzes the structural samples of loess using CT tomography and mercury intrusion methods in the southern plateau of Jingyang, Shaanxi Province. The changes in meso and micro pore structure characteristics with the burial depth of loess are observed and revealed. The results show that Jingyang shallow loess can be divided into three layers according to its pore structure characteristics: ① 1−2 m as the first layer, 3−4 m as the second layer, and 5 m as the third layer; ② The diameter of more than 95% of the total pores are less than 1.0 mm, which mainly are spherical and columnar closed pores; ③ while more than 65% of the total pore are larger than 0.8 mm, and most of them are branched and columnar connected pores; ④ With depth increasing, the pore connectivity gradually decreases, and the deformation and failure of macropores play a key role in the stability of loess structure; ⑤ In the mercury intrusion test, intragranular pores are bounded by 0.2 μm. The proportion of pores on the left side shows insignificant change with depth, while on the right side, it increases with depth. This study provides a basis for further exploring the micro pore seepage mechanism of shallow loess in the future.