穿河暗涵工程长期安全性及损伤模式研究

Study on Long⁃Term Safety Characteristics and Damage Mode of River Crossing Culvert Project

工程运行期的材料劣化对输水暗涵的长期安全性及损伤模式具有重要影响。为了给暗涵工程的建设和运行管理提供参考,以南水北调某穿河倒虹吸三孔一联暗涵工程为研究对象,基于裂缝带理论和微平面本构模型,采用数值模拟方法对其建模,分析了正常运行工况和极端荷载条件下暗涵混凝土结构长期运行安全性、损伤模式及缺陷(裂缝)随材料长期劣化的发展情况。结果表明:在内水压力和不均匀沉降的持续作用下,随着材料性能长期劣化,暗涵不同部位相继出现局部裂缝,裂缝总体上深度较大但宽度较小,长期运行中材料性能劣化不会影响工程的安全运行;当枯水期超负荷运行和检修期河道出现超大洪水时,暗涵侧墙外侧裂缝的总宽度和最大宽度均显著增大;初始缺陷(裂缝)的存在对暗涵的最终损坏形式没有显著影响,但对局部裂缝扩展有明显的促进作用,因此及时处理初始缺陷、定期对暗涵进行检修非常重要。

The material deterioration during the operation period of a project has an important impact on the long⁃term safety and damage mode of the water conveyance culvert.In order to provide reference for the construction and operation management of underground culvert pro⁃ject,taking a river crossing inverted siphon three hole one combination underground culvert project as the research object,based on the crack zone theory and micro plane constitutive model,the numerical simulation method was used to model it,and the long⁃term operation safety,damage mode and defects(cracks)of underground culvert concrete structure under normal operation conditions and extreme load conditions were analyzed with the development of long⁃term deterioration of materials.The results show that under the continuous action of internal water pressure and uneven settlement,with the long⁃term deterioration of material properties,local cracks appear one after another in different parts of the culvert.Generally,the depth of the cracks is larger but the width is smaller.The deterioration of material properties will not affect the safe operation of the project in long⁃term operation;The total width and the maximum width of cracks on the outside of the side wall of the culvert are increased significantly when the overload operation in the dry season and the super flood occurs in the river channel during the ma⁃intenance period;The existence of initial defects(cracks)has no significant impact on the final damage form of the concealed culvert,but it can significantly promote the local crack propagation.Therefore,it is very important to deal with the initial defects in time and repair the con⁃cealed culvert regularly.