Abstract To test the voids between the tunnel bottom and the cushion, the impact imaging method is used for the baseplate tightness test of the prefabricated long-segment and large-tonnage utility tunnel in Xiong'an New Area and the baseplate tightness evaluation indicator suitable for the prefabricated utility tunnel is put forward. The immersion testing was performed to research the influence of immersion in rainwater on the contact status between the tunnel bottom and the leveling course and analyze the influence of the measuring point layout with the impact imaging method on the results of bottom contact status testing. The results show that (1) the impact response strength of 1.79 can be used as the evaluation indicator for the bottom contact status testing of the prefabricated utility tunnel with the impact imaging method, the reliability of judging and identifying the bottom defects can be more than 85%, and the area where any voids on the tunnel bottom exist can be accurately identified; (2) The immersion in rainwater for a short time will cause the whole utility tunnel to sink, make the cushion layer more compact, and improve the contact status of the tunnel bottom; (3) Based on the impact imaging method, the 500 mm×500 mm measuring point layout used in testing the contact status of the utility tunnel bottom has a void identification accuracy that can meet the demands for engineering applications, as well as a higher testing efficiency.
Abstract：
To test the voids between the tunnel bottom and the cushion, the impact imaging method is used for the baseplate tightness test of the prefabricated long-segment and large-tonnage utility tunnel in Xiong'an New Area and the baseplate tightness evaluation indicator suitable for the prefabricated utility tunnel is put forward. The immersion testing was performed to research the influence of immersion in rainwater on the contact status between the tunnel bottom and the leveling course and analyze the influence of the measuring point layout with the impact imaging method on the results of bottom contact status testing. The results show that (1) the impact response strength of 1.79 can be used as the evaluation indicator for the bottom contact status testing of the prefabricated utility tunnel with the impact imaging method, the reliability of judging and identifying the bottom defects can be more than 85%, and the area where any voids on the tunnel bottom exist can be accurately identified; (2) The immersion in rainwater for a short time will cause the whole utility tunnel to sink, make the cushion layer more compact, and improve the contact status of the tunnel bottom; (3) Based on the impact imaging method, the 500 mm×500 mm measuring point layout used in testing the contact status of the utility tunnel bottom has a void identification accuracy that can meet the demands for engineering applications, as well as a higher testing efficiency.
MA Huabing1 SHAN Hongwei1 GUO Yawei2 FU Baiyong2 SHANGGUAN Shiqing3
.Study on Full-scale Test for Bottom Contact Status of Prefabricated Utility Tunnel Based on Impact Imaging Method[J] MODERN TUNNELLING TECHNOLOGY, 2022,V59(6): 162-169
2022, Vol. 59 