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Abstract

By taking the ultra-shallow buried construction of Xinwu Tunnel in Luoding–Xinyi Expressway in Guangdong Province as the engineering background, the key construction parameters and formation reinforcement effect of high-pressure rotary churning pile in ultra-shallow buried tunnel surrounding rock of fully weathered strata were compared. The results show that: ① slurry pressure, rotary churning speed, and lifting speed have obvious effects on the static load bearing capacity of a single pile. Under the same static load condition, greater slurry pressure indicates a lower cumulative settlement value of a single pile and a smaller increase in cumulative settlement value, and the change rate of rebound value is basically the same. With the increase in rotary churning speed, the lower cumulative settlement value of a single pile means that the change rate of the cumulative settlement value of a single pile decreases, and the change rate of rebound value decreases. With the increase in lifting speed, the cumulative settlement value of a single pile increases, and the change rate of cumulative settlement value decreases; the change rate of rebound value basically remains unchanged. ②The cement soil of the pile body is uniform and brittle, with high strength, and the formation at the slurry site is mainly a loose silty clay layer and sand-bearing layer. ③After the bottom of the tunnel is strengthened by a high-pressure rotary churning pile, the top surrounding rock is more stable after the excavation of the ultra-shallow buried tunnel, and the cracks between the surrounding rock are filled with cement slurry; the integrity is improved. The pile body effectively limits the deformation of the soil outside the side wall to the inside of the tunnel and plays a certain role in stopping water. The reinforcement by a high-pressure rotary churning pile improves the integrity of surrounding rock, consolidates the soft soil above the tunnel arch, and creates conditions for the safe excavation of the shallow buried section of the tunnel.

Publication Date

3-17-2023

DOI

10.14048/j.issn.1671-2579.2023.01.027

First Page

155

Last Page

161

Submission Date

March 2025

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