Mohammad Omidi manesh - Mining Engineering Department, Hamedan University of Technology, Hamedan, Iran
Vahab Sarfarazi - Mining Engineering Department, Hamedan University of Technology, Hamedan, Iran
Nima Babanouri - Mining Engineering Department, Hamedan University of Technology, Hamedan, Iran
Amir Rezaei - Mining Engineering Department, Hamedan University of Technology, Hamedan, Iran

This work presents the hollow center cracked disc (HCCD) test and the cracked straight through Brazilian disc (CSTBD) test of oil well cement sheath using the experimental test and Particle Flow Code in two-dimensions (PFC۲D) in order to determine mode I fracture toughness of cement sheath. The tensile strength of cement sheath is ۱.۲ MPa. The cement sheath model is calibrated by outputs of the experimental test. Secondly, the numerical HCCD model and CSTBD model with diameter of ۱۰۰ mm are prepared. The notch lengths are ۱۰ mm, ۲۰ mm, ۳۰ mm, and ۴۰ mm. The tests are performed by the loading rate of ۰.۰۱۸ mm/s. When the notch length in CSTBD is ۴۰ mm, the external work is decreased ۴۸%, related to the maximum external work of model with notch length of ۱۰ mm (۰.۲۲۵ KN*mm decreased to ۰.۱۱۶ KN*mm). When the notch length in HCCD is ۳۰ mm, the external work is decreased ۳۳%, related to the maximum external work of model with notch length of ۱۰ mm (۰.۰۶ KN*mm decreased to ۰.۰۴ KN*mm). The fracture energy is largely related to the joint length. The fracture energy is decreased by increasing the notch length. In constant to the notch length, the fracture energy of the CSTBD model is more than the HCCD model. Mode I fracture toughness is constant by increasing the notch length. The HCCD test and the CSTBD test yield a similar fracture toughness due to a similar tensile stress distribution on failure surface. The experimental outputs are in accordance to the numerical results.

HCCD, CSTBD, mode I fracture toughness, cement slurry, Discrete Element Method