Investigation on performance of a large circular pit-in-pit excavation in claygravel-cobble mixed strata
Investigation on performance of a large circular pit-in-pit excavation in claygravel-cobble mixed strata
复制标题
粘土卵石混合地层大型圆形坑中坑开挖性能研究
DOI：
10.1016/j.tust.2018.06.023
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发表时间：
2018
影响因子：
6.9
通讯作者：
汪大龙
中科院分区：
文献类型：
--
作者：
谭勇;陆烨;徐长节;汪大龙
独特的凹坑（PIP）发掘，包括外部直径较大的圆形凹坑和更较小的深凹坑。内部的矩形凹坑是在粘土砂锅中构建的。为了确保项目安全性以及PIP发掘的表征，请研究内坑开挖对外坑性能的影响，并探索在离散地材料中动员的横向地球压力，该项目被广泛进行了仪器。现场数据表明，它从文献中的发掘中明显执行。该发掘引起了相对较小的墙壁和地面位移，这两者都具有独特的作用。当前的经验和半经验方法预测发掘性能不再适用于这种情况。为了控制PIP发掘的性能，限制内部坑的壁运动至关重要。与以前的认可相反，发生了由于发掘而产生的基础反弹。不仅在柔软的粘土中，而且还处于僵硬到坚硬的粘土，粘土碎的混合物，甚至是分解的底石。在细颗粒土壤中的差异差异。岩石颗粒的力。经典的兰金理论基本上低估了当前的经验。为了设计PIP开挖，内部和外部固定壁之间的地面应被视为在开挖外坑期间被视为被动状态，而当随后在内壁上发掘时，在内壁比外壁更大的偏转率时，将其视为活跃状态。在挖掘内坑之前，外坑的基本基准板的铸造头是一种具有成本效益的解决方案。将墙壁脚趾插入基础分解的基岩中，大大减轻了与墙踢有关的潜在风险。
A unique pit-in-pit (PIP) excavation, which comprised a large diameter circular pit outside and a smaller deeper.rectangular pit inside, was constructed in clay-gravel-cobble mixed strata. To guarantee project safety as well as.characterize behavior of PIP excavation, investigate influence of inner pit excavation on outer pit performance.and explore lateral earth pressure mobilized in discrete geomaterials, this project was extensively instrumented.throughout construction. Field data indicated that it performed distinctly from those excavations in literature..This excavation caused relatively smaller wall and ground displacements, both of which featured distinctive.profiles; current empirical and semi-empirical approaches for predicting excavation performance were not applicable to this case any more. To control performance of PIP excavation, it is of paramount importance to limit.lateral wall movement of inner pit. Contrary to previous recognition, basal rebound due to excavation took place.not only in soft clay, but also in stiff to hard clay, clay-gravel-cobble mixtures, and even decomposed bedrock..Different from those in fine grained soils, magnitudes of lateral earth pressures against retaining wall in claygravel-cobble mixtures showed a wide range of scattering and their thrusts were transferred to wall mainly via.contact force of rock particles. Classic Rankine theory substantially underestimated while current empirical.apparent earth pressure (AEP) diagrams highly overestimated magnitude of lateral active earth pressure of claygravel-cobble mixtures. For design of PIP excavation, the ground between inner and outer retaining walls should.be treated as the passive state during excavation of outer pit, while as the active state during subsequent excavation of inner pit when greater increment of deflection occurred to inner wall than outer wall. Casting head of.inner wall inside base slab of outer pit prior to excavation of inner pit was a cost-effective solution for enhancing.excavation performance; socketing wall toe into underlying decomposed bedrock significantly mitigated potential risk associated with wall kicking.