A Sensitivity Analysis of the Anisotropy of Hydraulic Conductivity to the Seepage, Deformation and Stability of Anti-dipping Layered Rock Slopes: A Case Study of the Pulang Area in Southwestern China

AbstractIn this paper, in order to study the influence of anisotropy ratios and anisotropy directions on the seepage, deformations and stability of the anti-dipping layered rock slopes, Geo-studio software was used in this study for the numerical analysis of carbonaceous slate slopes on the unsaturated seepage, fluid–solid coupling, and stability theory in Pulang area. The results showed that the maximum surface water content of the layered rock slopes gradually decreased with increases of the water conductivity anisotropy ratio and decreases in the anisotropy angle of the anti-dipping layered rock slopes. In addition, the rainfall infiltration depths in the middle sections of the slopes were observed to be the most affected by the anisotropy ratio and dip angles of the rock formations. Meanwhile, the bottom sections of slopes were the least affected by the anisotropy ratio and the dip angles of the rock formations. In regard to the anti-dipping rock slopes, it was found that the anisotropy ratio and rock layer dip angles should be considered in the deformation and stability analyses. When the seepage of an anti-dipping layered slope was considered to be isotropic, the safety factors often were overestimated. As the anisotropy ratio decreases and the anti-dipping angles of the layered planes increases, the safety factors of the slopes will gradually decrease. This study provided a feasible scheme for evaluating the seepage, deformations and stability of the anti-dipping layered rock slopes in southwest China’s Pulang area.

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A Sensitivity Analysis of the Anisotropy of Hydraulic Conductivity to the Seepage, Deformation and Stability of Anti-Dipping Layered Rock Slopes: A Case Study of the Pulang Area in Southwestern China

10.21203/rs.3.rs-172431/v1 ◽

2021 ◽

Author(s):

Guangkeng Zhang ◽

Guangyin Lu ◽

Chengzhi Xia ◽

Lianrong Wu ◽

Zongming Xu ◽

...

Keyword(s):

Anisotropy Ratio ◽

Rock Slopes ◽

Safety Factors ◽

Water Conductivity ◽

Conductivity Anisotropy ◽

Layered Rock ◽

Rock Formations ◽

Layered Slope ◽

Unsaturated Seepage

Abstract In this paper, in order to study the influencing effects of anisotropy ratios and anisotropy directions on the seepage, deformations and stability of the anti-dipping layered rock slopes, Geo-studio software was used in this study to carry out this test based on the unsaturated seepage, fluid-solid coupling, and stability theory numerical analysis of carbonaceous slate slopes in Pulang area. The results showed that the maximum surface water content of the layered rock slopes gradually decreased with increases of the water conductivity anisotropy ratio and decreases in the anisotropy angle of the anti-dipping layered rock slopes. In addition, the rainfall infiltration depths in the middle sections of the slopes were observed to be the most affected by the anisotropy ratio and dip angles of the rock formations. Meanwhile, the bottom sections of slopes were the least affected by the anisotropy ratio and the dip angles of the rock formations. In regard to the anti-dipping rock slopes, it was found that the anisotropy ratio and rock layer dip angles should be considered in the deformation and stability analyses. When the seepage of an anti-dipping layered slope was considered to be isotropic, the safety factors often were overestimated. As the anisotropy ratio decreases and the anti-tilt angles of the layered planes increases, the safety factors of the slopes will gradually decrease. This study provided a feasible scheme for evaluating the seepage, deformations and stability of the anti-dipping layered rock slopes in southwest China’s Pulang area.

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Deformation and Stability Characteristics of Layered Rock Slope Affected by Rainfall Based on Anisotropy of Strength and Hydraulic Conductivity

Water ◽

10.3390/w12113056 ◽

2020 ◽

Vol 12 (11) ◽

pp. 3056

Author(s):

Chengzhi Xia ◽

Guangyin Lu ◽

Ziqiang Zhu ◽

Lianrong Wu ◽

Liang Zhang ◽

...

Keyword(s):

Hydraulic Conductivity ◽

Factor Of Safety ◽

Rock Slope ◽

Horizontal Displacement ◽

Field Monitoring ◽

Monitoring Data ◽

Anisotropy Ratio ◽

Conductivity Anisotropy ◽

Layered Rock ◽

Dip Angle

The strength and hydraulic conductivity anisotropy of rock slopes have a great impact on the slope stability. This study took a layered rock slope in Pulang, Southwestern China as a case study. The strength conversion equations of the seriously weathered rock mass were proposed. Then, considering the anisotropy ratio and anisotropy angle (dip angle of bedding plane) of strength and hydraulic conductivity, the deformation and stability characteristics of rock slope were calculated and compared with field monitoring data. The results showed that the sensitivity analysis of strength and hydraulic conductivity anisotropy could successfully predict the occurrence time, horizontal displacement (HD), and the scope of the rock landslide. When the anisotropy ratio was 0.01 and the dip angle was 30°, the calculated HD and scope of the landslide were consistent with the field monitoring data, which verified the feasibility of the strength conversion equations. The maximum horizontal displacement (MHD) reached the maximum value at the dip angle of 30°, and the MHD reached the minimum value at the dip angle of 60°. When the dip angle was 30°, the overall factor of safety (FS) and the minimum factor of safety (MFS) of the rock slope were the smallest. By assuming that the layered rock slope was homogeneous, the HD and MHD would be underestimated and FS and MFS would be overestimated. The obtained results are likely to provide a theoretical basis for the prediction and monitoring of layered rock landslides.

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Sensitivity Analyses of the Seepage and Stability of Layered Rock Slope Based on the Anisotropy of Hydraulic Conductivity: A Case Study in the Pulang Region of Southwestern China

Water ◽

10.3390/w12082314 ◽

2020 ◽

Vol 12 (8) ◽

pp. 2314 ◽

Cited By ~ 1

Author(s):

Chengzhi Xia ◽

Guangyin Lu ◽

Dongxin Bai ◽

Ziqiang Zhu ◽

Shuai Luo ◽

...

Keyword(s):

Hydraulic Conductivity ◽

Factor Of Safety ◽

Rock Slope ◽

Pore Water Pressure ◽

Water Pressure ◽

Sensitivity Analyses ◽

Southwestern China ◽

Anisotropy Ratio ◽

Rock Slopes ◽

Layered Rock

In the study of the seepage characteristics of layered rock slope under rainfall conditions, the majority of previous research has considered the hydraulic conduction to be isotropic, or only considered the anisotropy ratio of the hydraulic conductivity, ignoring the anisotropy angle. In the current study, a layered rock slope in the Pulang region was selected as an example. Then, based on the fitting parameters of the Van Genuchten model, pore water pressure sensitivity analyses of the layered rock slope were carried out. The anisotropy ratio and anisotropy angle were used to analyze the sensitivity of the seepage and stability of the layered rock slopes. The results show that as the anisotropy angle of hydraulic conductivity of layered rock slope decreased, the maximum volume water content of surface (MWCS) of layered rock slope gradually increased. Additionally, as the anisotropy ratio decreased and the anisotropy angle increased, the rising heights of the groundwater (RHG) of layered rock slope gradually increased. When the hydraulic conduction of layered rock slope was considered isotropic, the factor of safety (FS) tended to be overestimated. As the anisotropy ratio decreased and the anisotropy angle increased, the factor of safety (FS) of layered rock slope decreased. Prevention should be the objective for rock slopes with larger dip angles in the bedding plane in the Pulang region. This study provides feasible schemes for the evaluation of the seepage and stability of layered rock slopes in Pulang region of southwestern China.

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Role of bedrock on stream conductivity and groundwater contribution to streams: a case study from Jhikhu Khola watershed, central Nepal

Journal of Nepal Geological Society ◽

10.3126/jngs.v18i0.32260 ◽

1998 ◽

Vol 18 ◽

Author(s):

G. Nakarmi ◽

T. Li

Keyword(s):

Stream Flow ◽

Flow Direction ◽

Annual Rainfall ◽

Water Conductivity ◽

Water Storage Capacity ◽

Central Nepal ◽

Rock Formations ◽

Groundwater Condition

Role of rock formations on water conductivity and groundwater condition contributing to stream flow was examined in the Jhikhu Khola watershed, central Nepal. More than 75% of annual rainfall occurring between June and September which recharges the groundwater. Carbonate rocks are responsible for the higher conductivity values whereas mica schist and quartzite yield little flow with low conductivity during dry season. For better understanding of the water storage capacity of the rock formations, detail studies on distribution of fissures and cavities in the rocks are essential. Application of selected tracer will assist to evaluate flow direction and quantify the rate of flow.

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