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原位应力对桥梁的状态与可靠度评估具有重要意义。针对桥梁混凝土结构服役年限较长、实际受力状态复杂、构件尺寸较大以及单轴受力控制的特点,通过单轴应力释放影响函数建立了未知原位应力状态与表面释放应变之间的对应关系。以薄壁环作为释放区域,借助有限元标定了不同测量区域的影响函数。通过分步钻入试验,尝试识别处于单轴均匀应力场下的混凝土试块的原位应力。结果表明:影响函数能够有效反映原位应力与表层释放应变的对应关系,与试验结果吻合,识别方法具有可行性与适用性;多应变计综合识别能有效降低混凝土不均匀性与随机性引起的识别误差,对多步识别结果的优化求解可以进一步提高精度;识别结果的稳定性与应变计敏感栅尺寸有关。
In-situ stress is important for the assessment of bridge status and reliability. Aiming at the characteristics of long service life of bridge concrete structure, complex actual stress state, large component size and uniaxial force control, the correspondence between the unknown in situ stress state and the surface release strain is established by the uniaxial stress release influence function relationship. Using the thin-walled ring as the release area, the influence function of different measurement areas was calibrated by finite element method. By step-by-step drilling into the test, try to identify the in-situ stress of the concrete block under a uniform uniaxial stress field. The results show that the influence function can effectively reflect the corresponding relationship between in-situ stress and surface strain, and coincides with the experimental results. The identification method is feasible and applicable. The comprehensive identification of multi-strain gauges can effectively reduce the heterogeneity and randomness of concrete The recognition error can further improve the accuracy of the multi-step recognition result. The stability of the recognition result is related to the sensitive grid size of the strain gage.