Experimental Study on the Fracture Characteristics of Paraffin-Based Phase Change Material–Mixed Soil

The paraffin-based phase change material (PPCM) has provided a novel solution to the antifreezing and temperature control of core wall soil. However, as a new filling material for dam core walls, the PPCM-mixed soil (PS) may increase the brittleness and the risk of hydraulic fracturing failure to the core wall. In this paper, a three/four-point bending test device with horizontal loading was developed to investigate the fracture characteristics and failure criteria of PS. The results show that the increase of PPCM content and the decrease of dry density will reduce the fracture toughness of PS. The elliptic equation with the fracture toughness of Mode I (open fracture) and Mode II (sliding fracture) as the axial length is more suited to describing the results of the fracture toughness test for PS with different PPCM contents. Combined with the relationship between the fracture angle and the ratio of the stress intensity factor, the fracture failure criterion of PS under different PPCM contents can be presented. These research results can provide a theoretical support for further analysis of core wall failure and hydraulic fracturing risk.