AUTHOR=Liu Tao , Du Tiantian , Lu Huaming , Hu Baichun , Yang Xun , Liu Gang 

TITLE=The influence of cement proportion and curing age on the mixed mode I-II fracture characteristics of cement soil

JOURNAL=Frontiers in Materials

VOLUME=10

YEAR=2024

URL=https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2023.1342249

DOI=10.3389/fmats.2023.1342249

ISSN=2296-8016

ABSTRACT=<p>To study the fracture failure mechanism of cement soil under tensile-shear stress, mixed mode I-II fracture tests were conducted on cement soil semi-circular bending specimens with different cement proportions (<italic>p</italic> = 5%, 10%, 15%, 20%, and 25%) and curing ages (<italic>T</italic> = 1, 3, 5, and 7 days). The test results showed that the cracks were jagged as they propagated, and mode I stress intensity factor (<italic>K</italic><sub>I</sub>) and mode II stress intensity factor (<italic>K</italic><sub>II</sub>)gradually increased with the increase of cement proportion and curing age. In addition, the <italic>K</italic><sub>II</sub>/<italic>K</italic><sub>IC</sub> values were between 0.39 and 0.45 under different cement proportions and between 0.40 and 0.44 under different curing ages. Subsequently, the limitations of using traditional fracture criteria (MTS, S, G, and circular criteria) to describe cement soil fracture damage were identified. In contrast, the generalized maximum tangential stress (GMTS) criterion fitted the test results well, with the <italic>K</italic><sub>II</sub>/<italic>K</italic><sub>IC</sub> value and the crack initiation angle near the critical size <italic>r</italic><sub>c</sub> = 1 mm curve. Based on the generalized maximum tangential stress (GMTS) criterion, the <italic>r</italic><sub>c</sub> of the cement soil crack tip micro-fracture zone was calculated as 0.3 mm–1.9 mm.</p>