Influence of Construction of Deep Excavation Groups on Adjacent Shallowly Buried Pipelines in Soft Clay

In order to understand the impact of construction of large deep excavation groups on adjacent shallowly buried underground pipelines in soft clay, the influences of diaphragm wall construction and zoned excavation on pipelines settlements were analyzed by the field instrumentation data. The results show that during the construction of the deep excavation group, the underground pipelines settlements exhibited significant additive effects. Pipelines are affected by the excavation of multiple adjacent foundation pits. The ratio of the total settlement of underground pipelines to the equivalent excavation depth (He) ranged from 0.11% to 0.55%. The maximum ratio of pipeline settlement caused by diaphragm walling to total settlement can reach 50%. The main affected area during the diaphragm wall construction was 0.3Hw (diaphragm wall depth), and the subordinate affected area was 0.3Hw-1.5Hw. Settlements of the main affected area during diaphragm walling ranged from 0.02% Hw to 0.09% Hw. The main affected area of the foundation pit groups excavation was 1.0He, and the subordinate affected area was 1.0He-4.5He, where He is the equivalent excavation depth of the foundation pit groups. Settlements of the underground pipeline in the main affected area during the excavation groups construction ranged from 0.18% He to 0.39% He. The settlements of shallowly buried underground pipelines decreased as the distance between pipelines and deep excavation increased. The settlements of shallowly buried pipelines caused by adjacent excavation groups were predominantly governed by the distances between pipelines and deep excavation and less influenced by pipeline relative stiffness and buried depth. © 2023 Xi'an Highway University. All rights reserved.