Effect of Rock Abrasiveness on Wear of Shield Tunnelling in Bukit Timah Granite

The abrasiveness of rocks significantly influences the wear endured by excavation tools in tunnel boring machines (TBMs). In slurry shield TBMs, wear occurs not only in excavation tools but also in discharge pipes and pumps of slurry transport systems. To explore this phenomenon, this study investigated the effect of rock abrasiveness on the wear of both disc cutters and slurry discharge pipes in slurry shield TBMs. The radial wear of disc cutters and the thickness of slurry discharge pipes were measured and monitored at a TBM site in Singapore. The relationship between the weathering grade of Bukit Timah granite and the wear coefficient of disc cutters was analysed, and a correlation between the Cerchar Abrasivity Index values and the wear coefficient of 19 inch disc cutters was suggested. Additionally, the average wear rates of slurry discharge pipes used for Bukit Timah granite were determined based on the pipe thickness measurements. The wear rates of weathering grades G(I) to G(IV) of Bukit Timah granite were observed to be highly similar to each other, whereas the wear rates of G(V) grade and mixed ground were 1.55 times higher than those of the G(I) to G(IV) grades. The correlation between the slurry discharge velocity and the wear rate in slurry discharge pipes was thus derived. The accurate assessment of the effect of rock abrasiveness on both the wear of disc cutters and the wear rate in slurry discharge pipes, investigated in this paper, will highlight the need for efficient maintenance of the excavation tools in TBMs and encourage the development of various equipment wear prevention measures in order to minimize overall construction costs and time.

On the Experimental Investigation of Rock Abrasiveness in Petroleum Engineering

By means of developing new rock abrasiveness device and using quenching steel spiral simulation micro-bit, the experimental investigation on rock abrasiveness that simulating the actual drilling surroundings in petroleum engineering had been conducted. based on the data of micro-bit’s wear weight, which broke unit volume rock, of which experimental samples are made from more than 850 cores of seven main geological profiles in Shengli oilfield, rock abrasiveness is divided into eight grades with Sturges empirical formula. The bit type selection and the bit life prediction could be conducted with the upper experimental method.