摘要详情
50 / 2025-07-20 21:33:33
Triaxial Creep Mechanical Anisotropy Characteristics Test and Engineering Effects of Phyllite
Phyllite; Triaxial creep; Anisotropy; Moisture content; Asymmetric large deformation
摘要录用
In recent years, with the increasing number of deep-buried tunnels, especially those crossing weak rock formations, the problem of large squeezing deformation in high-ground-stress soft rock tunnels has become increasingly serious. Investigations on numerous tunnels with large deformations have shown that the large squeezing deformation of tunnels is not only characterized by obvious time-dependence, but also affected by factors such as lithological combination, stratum occurrence, rock mass structure, the spatial combination of in-situ stress direction and tunnel, and groundwater distribution, resulting in significant asymmetry in tunnel deformation. Particularly in phyllite and other layered soft rock tunnels, during tunnel excavation, the surrounding rock tends to undergo unloading effects, and after excavation, the surrounding rock is affected by creep effects for a long time. Moreover, the creep characteristics exhibit significant anisotropy with different bedding dip angles. Therefore, studying the creep characteristics of phyllite and analyzing its anisotropy are crucial for researching the asymmetric large deformation of tunnels.
To study the creep anisotropic characteristics of phyllite under different bedding conditions and moisture contents, specimens with four dip angles (0°, 30°, 60°, 90°) and four moisture contents (0.7%, 1.2%, 1.6%, 2.0%) were cross-combined to conduct triaxial unloading tests and triaxial unloading creep tests. Meanwhile, the asymmetric large deformation modes of phyllite tunnels under different dip angles were further explored. The test results show that: (1) Moisture deterioration has a significant impact on phyllite. When the moisture content increases from 0.7% to 2.0%, the peak strength decreases by an average of 50.93%, and the elastic modulus drops by an average of 83.9%. Under triaxial unloading conditions, phyllite exhibits obvious anisotropy, and the peak compressive strength shows a "U" - shaped characteristic with the increase of bedding dip angle. (2) Phyllite is prone to failure under the influence of loading modes, especially the specimens with 30° and 60° dip angles. At the same bedding angle, with the increase of axial load, the creep strain shows a "U" - shaped trend due to the influence of pore compaction and rock damage. At the same moisture content, with the increase of bedding dip angle, the creep strain under the last level of load shows an increasing trend. (3) Considering the creep anisotropy of phyllite, different deformation - controlling factors of joint structure, and the influence of secondary stress distribution, through comprehensive mechanical analysis, the geomechanical mode of the tunnel with 0° dip angle is classified as the vault type b asymmetric mode, the geomechanical modes of tunnels with 30° and 60° dip angles are classified as the sidewall type b asymmetric mode, and the geomechanical mode of the tunnel with 90° dip angle is classified as the sidewall type b asymmetric mode.
To study the creep anisotropic characteristics of phyllite under different bedding conditions and moisture contents, specimens with four dip angles (0°, 30°, 60°, 90°) and four moisture contents (0.7%, 1.2%, 1.6%, 2.0%) were cross-combined to conduct triaxial unloading tests and triaxial unloading creep tests. Meanwhile, the asymmetric large deformation modes of phyllite tunnels under different dip angles were further explored. The test results show that: (1) Moisture deterioration has a significant impact on phyllite. When the moisture content increases from 0.7% to 2.0%, the peak strength decreases by an average of 50.93%, and the elastic modulus drops by an average of 83.9%. Under triaxial unloading conditions, phyllite exhibits obvious anisotropy, and the peak compressive strength shows a "U" - shaped characteristic with the increase of bedding dip angle. (2) Phyllite is prone to failure under the influence of loading modes, especially the specimens with 30° and 60° dip angles. At the same bedding angle, with the increase of axial load, the creep strain shows a "U" - shaped trend due to the influence of pore compaction and rock damage. At the same moisture content, with the increase of bedding dip angle, the creep strain under the last level of load shows an increasing trend. (3) Considering the creep anisotropy of phyllite, different deformation - controlling factors of joint structure, and the influence of secondary stress distribution, through comprehensive mechanical analysis, the geomechanical mode of the tunnel with 0° dip angle is classified as the vault type b asymmetric mode, the geomechanical modes of tunnels with 30° and 60° dip angles are classified as the sidewall type b asymmetric mode, and the geomechanical mode of the tunnel with 90° dip angle is classified as the sidewall type b asymmetric mode.
重要日期
-
会议日期
08月23日
2025
至08月26日
2025
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07月21日 2025
初稿截稿日期
-
08月26日 2025
注册截止日期
主办单位
Southwest Jiaotong University, China (SWJTU)
International Consortium on Geo-disaster Reduction (ICGdR)
UNESCO Chair on Geoenvironmental Disaster Reduction
International Consortium on Geo-disaster Reduction (ICGdR)
UNESCO Chair on Geoenvironmental Disaster Reduction
承办单位
Southwest Jiaotong University, China (SWJTU)
International Consortium on Geo-disaster Reduction (ICGdR)
UNESCO Chair on Geoenvironmental Disaster Reduction
International Consortium on Geo-disaster Reduction (ICGdR)
UNESCO Chair on Geoenvironmental Disaster Reduction
联系方式
- Yufeng Wang
- wa******@swjtu.edu.cn
- +86********
