Wei-Hong Yang , Dong Su , Xing-Tao Lin , Zhi-Jia Lv , Zhan-Hu Yao , Hui Li , Ya-Zhou Zhang , Xiang-Sheng Chen
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引用次数: 0
Abstract
Boulders pose substantial challenges in coastal urban tunnel engineering. This study, for the first time, utilizes extensive closely spaced borehole data from 3486 drilling points obtained during actual tunnelling through boulder strata to evaluate the effectiveness of microtremor detection, analyze variations in operational parameters, and assess the efficiency of blasting treatment. Additionally, leveraging borehole data, a 3D reconstruction of the soil-boulder-bedrock stratum was developed, and the stratum content ratio at the excavation face was derived. A multivariate linear regression model was established to explore the relationship between boulder geology and construction parameters. The results demonstrated that microtremor surveys effectively identified boulder distributions by analyzing horizontal-to-vertical spectral ratio curves and differences in surface wave phase velocity. Field drilling confirmed the high accuracy of microtremor predictions, particularly in areas with dense or thick boulder layers. Post-blasting secondary drilling revealed boulder fragments smaller than 30 cm, meeting the operational requirements for shield cutter and crusher systems. The presence of boulders was found to increase thrust, torque, and overturning moments, as well as cause abnormal cutter wear. Blasting significantly reduced the standard deviation of operational data, demonstrating its effectiveness in stabilizing tunnelling performance. Regression analysis showed a strong correlation between geological conditions and tunnelling parameters, with results indicating that blasting operations effectively mitigate the adverse impacts of boulders on shield tunnelling performance. This study aims to provide valuable insights and references for future engineering projects encountering similar complex geological conditions.
期刊介绍:
Transportation Geotechnics is a journal dedicated to publishing high-quality, theoretical, and applied papers that cover all facets of geotechnics for transportation infrastructure such as roads, highways, railways, underground railways, airfields, and waterways. The journal places a special emphasis on case studies that present original work relevant to the sustainable construction of transportation infrastructure. The scope of topics it addresses includes the geotechnical properties of geomaterials for sustainable and rational design and construction, the behavior of compacted and stabilized geomaterials, the use of geosynthetics and reinforcement in constructed layers and interlayers, ground improvement and slope stability for transportation infrastructures, compaction technology and management, maintenance technology, the impact of climate, embankments for highways and high-speed trains, transition zones, dredging, underwater geotechnics for infrastructure purposes, and the modeling of multi-layered structures and supporting ground under dynamic and repeated loads.