海域人工岛填筑及地下互通隧道施工对邻近桥梁桩基影响研究

针对深中通道东人工岛下穿广深沿江高速桥梁工程建设过程出现堆载开挖问题,为了保障临近桥梁安全运营,考虑土体硬化特性,重点研究了海域分层填筑及桥桩保护措施,以及人工岛隧道基坑下穿及并行既有桥梁桩基两类典型不利工况,分析了依托工程筑岛后互通隧道施工过程与桥梁结构之间的相互影响,提出了分层分块填土、钢板桩加固、旋喷桩加固等措施要点,以及隧道下穿和并行时基坑设计关键技术。结果表明:横桥向两侧分层交替填筑有利于降低对桥梁桩基的影响;钢板桩内先填土方案可降低桩身弯矩50%左右;支护桩从嵌入强风化岩至嵌入中风化岩过程,临近桩基变形可降低30%左右;采取针对性的桥桩保护措施可控制各种不利工况下桩身变形及裂缝在设计规范要求范围内,并保障邻近广深沿江高速桥梁正常运营安全。研究成果可为类似海域明筑地下互通设计与施工安全提供有益的参考。

Study on influences from filling of artificial island in sea area and construction of underground interchange tunnel on adjacent bridge pile foundation

Aiming at the engineering problem from the preloading excavation for the project of downward crossing the bridge of Guangzhou Shenzhen Highway along the Pearl Ｒiver for the eastern artificial island of Shenzhong Channel，the layered filling and the bridge pile protection measures in sea area as well as two kinds of typical unfavorable working conditions of the artificial island tunnel foundation pit downward-crossing and parallelly passing the existing bridge pile foundation are emphasically studied herein under the consideration of the hardening characteristics of soil mass therein，so as to ensure the safe operation of the bridge nearby，while the interactive influence between the construction of the interchange tunnel after the filling of the island and the relevant bridge structure are analyzed，and then the main points of the measures such as layered and sectionalized filling，steel sheet pile reinforcement，jet grouting pile reinforcement，etc. as well as the key design technologies of the foundation pit for the downward crossing and parallelly passing are proposed herein as well. The study result shows that the layered-alternated filling on both the sides in the transverse direction of bridge is conducive to reduce the impact on the pile foundation of the bridge. The bending moment of the pile body can be decreased by about 50% with the scheme of prefilling inside of the steel sheet pile，while the deformation of the adjacent pile foundation can be decreased by about 30% during embedding the supporting pile from the strong weathered rock to the moderately weathered rock. The adoptions of the targetable bridge pile protection measures can control the pile body deformation and cracking under all the unfavorable working conditions within the range of the design specifications concerned，thus guarantee the operation safety of the bridge of Guangzhou Shenzhen Highway along the Pearl Ｒiver. The study result can provide beneficial reference for the design and construction safety of the underground interchange filled in the similar sea area.