Effect of Cement Injection on Shear Behaviour of Jointed Rock based on Mohr-Coulomb Criterion

Abstract

Common problem in mining activity is instability caused by jointed rock mass. The strength of jointed rock masscan be increased by cement injection. An artificial rock sample made from dental plaster type of moldano tara isused in this study to evaluate the influence of cement injection to the strength of jointed rock sample. The roughnessof joint surface are obtained from the natural rock joints and divided into three groups of Joint RoughnessCoefficient (JRC) values based on Barton criteria. The injection materials are mixture of cement and water withthe ratio of water and cement of 4: 5 and 3: 2. This artificial samples are then subjected to direct shear tests. Thetest results are analyzed by Mohr-Coulomb criterion to obtain the cohesion and internal friction angle. It isrevealed that cohesion and internal friction angle increased for injected rock sample. The strength increase variesby JRC condition. For Sample with JRC value between 8-10, the study find that injection material with water tocement ratio of 4:5 is more effective than cement injection with ratio of 3:2. For JRC value between 12-14, 16-18,and 18-20, it is found that cement injection with ratio of 3:2 is more effective than 4:5.

Analysis of Consolidation Grouting Effect on The Stability of Portal Slope of The Spillway Tunnel in The Bulango Ulu Dam, Gorontalo, Indonesia

“…Zakri et al [17] evaluate the influence of cement injection to the strength of jointed rock samples using an artificial rock type of moldano tara given the artificial joint with variation Joint Roughness Coefficient (JRC). The different water to cement ratio was injected into the artificial joint.…”

“…Grouting is an effective and practical method for improving rock properties [16]. Zakri et al (2018) analyzed an artificial rock sample made from dental plaster of the type of moldano tara after grouting injection and experienced an increase in cohesion and internal friction angle value using the direct shear test [17]. To evaluate the effectiveness of grouting, coring samples were taken after grouting at the check hole location (CH-01) see Figure 5.…”