A newly developed soil abrasion testing method for tunnelling using shield machines

The importance of the effect of ground abrasivity on the performance of a tunnel boring machine (TBM) is important for many tunnelling projects. In recent years, many abrasivity devices have been developed to measure soil abrasivity for specific conditions. In this paper a new device is developed to estimate the abrasivity of the soil for a wide range of site conditions. The device is designed on the basis of simulating the site conditions regarding the ground water, ground stresses and confining pressure of the TBM chamber, and the performance of the rotating cutter-head and pressurized shield tunnelling during its operation. A number of abrasivity tests were carried out on 12 types of crushed rock samples including six sedimentary rocks and six crystalline igneous and metamorphic rocks. The results showed that the abrasivity of the samples increased as equivalent quartz percentages of the sample increased. It was also found that the texture of the samples has a great influence on their abrasivity. To evaluate the performance of the newly developed device, the same samples were tested by other current abrasivity methods including the Cerchar test, Laboratoire Central des Ponts et Chaussees (LCPC) test and soil abrasion test (SAT). Comparisons of the results indicated close correlations, especially with the results for the Cerchar and LCPC devices.