Fracture process zone of mode I in compacted clay through digital image correlation

To study the generation characteristics and length variation of the soil fracture process zone (FPZ), mode I fracture tests were conducted on compacted clay specimens with different moisture contents and dry densities. Combined with the digital image correlation (DIC) method, the displacement fields of prefabricated crack tips at different loading stages were obtained. The results showed that the mode I fracture toughness (K-IC) increased and then decreased as moisture content increases, and increased linearly with dry density. As the load increased, the FPZ generation rate accelerated. The FPZ length at peak load ranged from 7.92 mm to 12.54 mm and continued to increase after peak load. The FPZ length calculated with the Schimdt model was lower than that measured by the DIC method. Finally, the differences in the FPZ lengths of compacted clay and rock-like materials were discussed.