Mechanical properties and cracking behaviors of limestone-like samples with two parallel fissures before and after grouting

In the present work, uniaxial compressive tests were carried out on limestone-like samples containing two parallel open fissures or cement-infilled fissures with different geometries. Mechanical property and crack behavior of limestone-like samples with two parallel open fissures or cement-infilled fissures were affected by bridge inclination angle and fissure inclination angle. Four types of coalescence of rock bridge for samples containing open fissures or cement-infilled fissures were summarized and classified. The closure of tensile crack was observed in the samples with small fissure inclination angle. This is a new phenomenon which is not mentioned in previous studies. Test results show that the peak strength, crack initiation stress, and coalescence type are different between open fissures and cement-infilled fissures. The reason for this phenomenon is that grouting of cement can transfer stress and reduce stress concentration at the flaw tip and rock bridge area.