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

Abstract

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.

Investigation of Disc Cutter Wear in Tunnel-Boring Machines (TBMs): Integration of Photogrammetry, Measurement with a Caliper, Weighing, and Macroscopic Visual Inspection

“…The wear of the cutter ring profile is usually measured physically using a special measuring tool: a wear ruler. This allows the amount of profile wear to be measured directly and in millimeters [18,26,36,38]. Wear rulers differ depending on the geometry of the cutter ring profile.…”

“…Several authors [7,11,12,[17][18][19][20][21] have noted that monitoring the wear condition of disc cutters and implementing predictive maintenance strategies are crucial to operational efficiency and cost management. Detailed discussions of wear measurement methods can be found in the following chapters, in which each method is examined in depth.…”

Prediction Model of Tunnel Boring Machine Disc Cutter Replacement Using Kernel Support Vector Machine

“…The data-driven method can predict disc cutter consumption and make maintenance plans before tunneling starts. Generally, the data-driven method can be classified into three kinds-empirical methods [18,19], mechanism-based methods [5,9,[20][21][22][23][24][25][26], and tunneling-parameters-based methods [8,12,27,28].…”

“…Empirical methods study the regression of cutter health indices and geological parameters based on historical data. Mechanism-based methods use energy theory or mechanical analysis to model the rock breaking process, then the disc cutter wear is mapped with relevant parameters, such as cutterhead rotation speed [20], penetration rate [5], normal force of single disc cutter [23], uniaxial compressive strength (UCS) [9], Cerchar abrasivity index (CAI) [24], cutterhead topological structure [25], and so on. With the disc cutter wear, disc cutter failure can be easily predicted.…”

Prediction of Subsidence during TBM Operation in Mixed-Face Ground Conditions from Realtime Monitoring Data

“…Mixed-face ground conditions during TBM driving pose the most challenging risks. The soft soil at the top of the face and the hard rock at the bottom makes it difficult to maintain a proper face-support pressure and face stability, and increases the risk of excessive cutter wear, face collapse, sinkholes, or damage to surrounding structures [1]. To avoid undesirable settlement and provide appropriate safety measures, engineers must reliably predict the amount of settlement under given ground conditions.…”