TBM Operation and Performance at the Silver Lake Project

Abstract

This thesis is written in cooperation with Herrenknecht. The main objectives of this thesis were to: Compare recorded TBM performance in soft ground with results from laboratory tests designed to estimate performance. Evaluate the influence and usefulness of soil conditioning additives, which are designed to reduce wear and torque and thus improve performance.The research was conducted by first doing a field study, which included recording essential TBM performance data, collecting soil samples and obtaining valuable knowledge from experienced people working on site. The samples have later been tested in the laboratory, and the recorded data has been processed. Literature studies have been used to discuss and better understand the results. It must be emphasized that this research is based on performance data from less than 90 meters of TBM tunneling. On the other hand, the documentation from this segment is very high, and all performances are based on a big amount of data.The two main laboratory tests are the Soil Abrasion Test (SATTM) and the Soft Ground Abrasion Test (SGAT). Other tests performed are grain size distribution analysis and XRD mineralogy analysis.Tests have shown that moisture content of soil samples collected for this thesis, and thus its compactibility can influence the soil abrasivity by as much as 500 %. A result of this high moisture influence is that the SGAT seems to have a better ability to predict TBM performance than SATTM.There is a clear correlation between recorded weight loss, torque and thrust from the SGAT tests, which increases the reliability of the test. Results from this work do indicate that results from the SGAT can be used to predict in-situ TBM performance. Adding foam to the sample reduces weight loss, torque and thrust. A reduction in abrasion of 60 % has been achieved, but this influence is very dependent on the soil and its moisture content and compactibility.