{'fraction_non_alphanumeric': 0.017857142857142856, 'fraction_numerical': 0.0010504201680672268, 'mean_word_length': 5.148387096774194, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Cumulative Damage Monitoring of Shotcrete in Large-Span Tunnel under Multiple-Blastings

In case of poor surrounding rock conditions, multiple-section blasting method is usually used in large-span tunnel. The sprayed concrete in tunnel will receive multiple blasting effects from different blasting section. Hence, its valuable to research the safety of sprayed concrete lining. Based on the field observation data and construction condition in Shizilong tunnel, The relation between initial velocity and crack length of different concrete age is obtained through indoor tests and the velocity is calculated when the length is 2mm. Then, with the mechanics theories of fracture and damage, the cumulative damage of rock and concrete is studied microcosmically and the increment expression is mended at the same time. The accuracy is verified based on a large number of data in the end, which is helpful for construction of large-span tunnels in future.