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《结构与土木工程前沿(英文)》 >> 2021年 第15卷 第2期 doi: 10.1007/s11709-021-0718-8

Experimental study on slurry-induced fracturing during shield tunneling

Key Laboratory of Urban Underground Engineering of the Education Ministry, Beijing Jiaotong University, Beijing 100044, China

收稿日期: 2021-03-29 录用日期: 2021-04-30 发布日期: 2021-04-30

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摘要

Facial support in slurry shield tunneling is provided by slurry pressure to balance the external earth and water pressure. Hydraulic fracturing may occur and cause a significant decrease in the support pressure if the slurry pressure exceeds the threshold of the soil or rock material, resulting in a serious face collapse accident. Preventing the occurrence of hydraulic fracturing in a slurry shield requires investigating the effects of related influencing factors on the hydraulic fracturing pressure and fracture pattern. In this study, a hydraulic fracturing apparatus was developed to test the slurry-induced fracturing of cohesive soil. The effects of different sample parameters and loading conditions, including types of holes, unconfined compressive strength, slurry viscosity, and axial and circumferential loads, on the fracturing pressure and fracture dip were examined. The results indicate that the fracture dip is mainly affected by the deviator stress. The fracturing pressure increases linearly with the increase in the circumferential pressure, but it is almost independent of the axial pressure. The unconfined compressive strength of soil can reflect its ability to resist fracturing failure. The fracturing pressure increases with an increase in the unconfined compressive strength as well as the slurry viscosity. Based on the test results, an empirical approach was proposed to estimate the fracturing pressure of the soil.

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