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Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, the performance of a high-pressure grouting material and consolidation body, the key parameters of tunnel surrounding rock reinforcement, and the field reinforcement effect are compared and studied. The results show that 1) the compressive strength, elastic modulus, and seepage resistance of the consolidation body are related to the water–cement ratio. The permeability of the consolidation body increases with increasing water–cement ratio under the constant head; under the condition of a certain water–cement ratio, the strength increases with an increase in cement content. To meet the construction requirements and the slurry stability, a small water–cement ratio is appropriate. 2) Slurry pressure, rotary spray speed, and lifting speed on the single pile static load bearing capacity have a significant impact. Under the same static load conditions, the greater the slurry pressure, the lower the cumulative settlement value of the single pile, the cumulative settlement value increases less, and the amount of change in rebound is the same; with the increase in the rotational speed of the rotary spray, the lower the cumulative settlement value of the single pile, and the rate of change of the cumulative settlement value of the single pile decreases; and with the increase in the lifting speed, the cumulative settlement value of the single pile increases and the rate of change of the cumulative settlement value decreases. 3) The pile body cement soil is more uniform, has high strength, and is brittle, and the stratum where the slurry part is located is a loose powder clay layer and sandy layer. 4) After high-pressure jet grouting pile reinforcement, the top surrounding rock is more stable after the excavation of an ultra-shallow buried tunnel, the fissures between the surrounding rocks are filled with cement soil consolidation, and the integrity is improved. Certain piles also play a certain role in stopping water; high-pressure jet grouting pile reinforcement to improve the integrity of the surrounding rock played a role in consolidating the weak soil layer above the tunnel vault, creating conditions for the safe excavation of the shallow buried section of the tunnel.

When shield machine is driving for a long distance, it is often forced to stop due to obstacles or excessive wear of tools, which is one of the main risks of shield construction. In order to summarize the research progress of shield opening technology in urban metro, the paper systematically summarizes the two technical ideas of normal pressure opening and pressurized opening, and summarizes the principle, risk factors and principles of shield opening under two technical conditions. Combined with typical engineering examples, the application scope, key technology, advantages and disadvantages of conventional compressed air and saturated gas method with pressure opening technology are analyzed and summarized. The engineering application of atmospheric pressure opening technology and atmospheric pressure cutter disc tool changing technology for soil grouting and freezing reinforcement is summarized. Finally, combined with the current research progress and the development trend of large diameter underwater shield in China, the paper analyzes the technical challenges faced by the shield opening in the future, discusses the direction of further research, and provides a reference for the development of shield opening technology in China.

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)