Abstract： Splitting cracks were found in the two-directional pre-stressed concrete walls of a large scale diversion project in north China. Based on internal structural characteristics of the wall, the impact imaging method (IIM) was applied for the detections of cracks distribution, seriousness and damage area ratio of the internal cracks and the damage cause analysis. The core test and numerical simulation by 3D FEM with prefabricated joints element were also adopted for verifications. The 56 drilled cores show that the IIM has high accuracy and resolutions on the internal crack distributions. This result provides reliable data for decisionsmaking of the wall repair strategies. Both field test results and numerical analysis show that the frost of the water inside the corrugated pipes that contain the prestressed tendon lead to the internal splitting cracks, due to the incompact grouting into the pipes. This accident shows the significance of the grouting quality control of the corrugated pipes inside the posttensioned structures in cold regions in northern China.
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