不确定地层属性相关的地下工程鲁棒性

Robustness of Underground Engineering Related to Uncertain Geological Conditions

提出地下工程结构设计体系的鲁棒性概念,建立地下结构力学响应与鲁棒性的联系,明确土压对地下结构鲁棒性产生的控制性影响,以典型地下结构桩基础为样本,讨论主被动土压-地下结构位移-破坏机理-体系鲁棒性之间的联成关系。给出鲁棒-应力解析模型,对不确定地层属性相关的软硬互层(如特殊液化滑移)、交界面地层中地下结构的鲁棒响应进行针对性评价。结合地下工程典型桩基的破坏实例,分析其破坏机理及鲁棒应力响应模式,以给出特殊边界条件下的应力解。对比桩基破坏的监测调查实例发现:桩基础等典型地下结构的整体鲁棒性特征与地上结构的鞭梢效应不同,呈现与不确定地层属性密切相关的类线性整体折断+局部塌沉特点,初步验证评价解析方法的有效性及实用性,为不确定地层属性相关地下工程的鲁棒性及地下结构设计提供一种对比参考。

The concept of robustness for the design system of underground engineering structure was put forward for the first time. The relationship between mechanical response and robustness of underground structures was established. The control effect of active and passive soil pressure on the robustness of underground structures was defined. Based on the typical sample of underground pile foundation, the relationship among the active/passive earth pressure, underground structure displacement, failure mechanism, and system robustness was discussed in detail. The practical robustness-stress model was presented, which was used to evaluate the robust response of the soft/hard layers （such as special liquefaction slip） related to uncertain geological conditions and the underground structures in the interface boundary layer. Based on the typical failure example of pile foundation in underground engineering, the failure mechanism and the model of the stress response were analyzed to facilitate the stress solution under special boundary conditions. The investigation that compared the pile foundation damage monitoring data found that the characteristics of the overall robustness of pile foundation were different to the whiplash effect of overground structure, showing the characteristics of linear integral fracture with local collapse, which was closely related to the uncertain geological conditions. The preliminary validity and practicability of the analytical method were validated, which provides a reference to the robustness evaluation and the design of underground engineering and structure.