Abstract
Abstract. In shield tunnel boring machine constructions, backfill pressure affects surface settlement and the stability of other underground structures nearby. Therefore, it is essential to pre-calculate backfill pressure in the design stage. This study examines and compares the seven internationally known backfill pressure calculation theories and calculates and analyzes the backfill pressures in six virtual ground conditions. The calculated backfill pressure increased as the ground cover increased, but the increase rate decreased. Also, this study performs a numerical analysis to identify the impact on ground settlement and tunnel crown settlement. In the end, settlement was more impacted by face pressure than backfill pressure in the unsaturated and saturated ground conditions. Also, as the ground cover increased, the impact of backfill pressure decreased, and as the applied face pressure decreased, the impact of backfill pressure increased.
Highlights
Tunnel excavations through the blasting method cause many complaints in cities due to noise and vibrations, leading to the rise of shield TBM that assembles segment lining while preventing the collapse of top ground with a shield at the same time as tunnel excavation
Afterwards, the calculated backfill pressure was applied to a numerical analysis to comparatively analyze the impact of the differences in backfill pressures in different models on the settlement of the ground and tunnel crown according to the ground conditions and ground cover
In the unsaturated conditions, ground settlement increased as ground cover increased, but settlement decreased in the saturated conditions, presumably because relaxed load applied as ground cover increased
Summary
Tunnel excavations through the blasting method cause many complaints in cities due to noise and vibrations, leading to the rise of shield TBM (tunnel boring machine) that assembles segment lining while preventing the collapse of top ground with a shield at the same time as tunnel excavation. The method has less risk of underground water inflow into the tunnel during tunnel excavation even under a high ground water pressure(level) in an unconfined aquifer This study examines and analyzes the backfill pressure calculation theories (models) that have been studied and suggested so far Afterwards, the calculated backfill pressure was applied to a numerical analysis to comparatively analyze the impact of the differences in backfill pressures in different models on the settlement of the ground and tunnel crown according to the ground conditions and ground cover
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