深大基坑支护方案的土工离心模型试验研究

Geotechnical Centrifuge Model Test Study on Deep and Large Foundation Pit Support Scheme

针对广深港客运专线福田站基坑"中心岛"开挖支护方案,从试验原理、模型设计、工况模拟及试验观测等方面提出应用土工离心模型试验研究深大基坑支护结构的安全性及基坑稳定性的试验模拟技术,测试混凝土连续墙的弯矩及土体的位移变形,结果表明:1)混凝土连续墙上的弯矩呈上大下小的分布趋势,远离基坑一侧受拉;2)基坑及附近土体均有不同程度的位移变形,由于试验与工程实际应力历史不同,试验测得沉降及变形均比实际工程现场测值偏大,离心模型试验结果偏于安全;3)基坑及附近各种加固措施有效抑制了土体的位移变形,提高了基坑的安全性。该试验技术对于深大基坑支护结构设计方案的论证、优选具有重要实践意义。

With the ＂ Center Island＂ excavation and support scheme in Futian station foundation pit in Guangzhou-Shenzhen-Hongkong passenger line as a background, test principle, model design, condition simulation, and test observations of the geotechnical centrifugal model test were provided. Geotechnical centrifugal model tests applied to study the safety and stability of the large and deep foundation pit support structure. The concrete continuous wall moment and the displacement deformation of soil were measured. Results show： 1 ） The concrete continuous wall moments present a distribution with the upper larger and the lower smaller and the far side of the foundation is under tension. 2） There are displacement and deformation of soil in foundation pit and its nearby regional, which is due to different stress path between centrifugal model test and practical engineering. The deformation measured in the test is larger than that of the practical engineering and test results show certain safety margins. 3 ） The displacement and deformation of soil is effectively inhibited by some reinforcement measures and the safety of foundation pit is also improved. These test results are important to optimize the foundation pit support structure design.