Effect of Rainfall Pattern and Crack on the Stability of a Red Bed Slope: A Case Study in Yunnan Province

Abstract

Red bed slopes in the southwest of China are associated with a grant number of geological hazards, such as landslides, mud-rock flows, and rock blocks falling, which are vital problems in geotechnical engineering. The damage can be induced or triggered due to a series of human and environmental activities, such as excavation, concentrated or long-term rainfall, earthquake, and fluctuation of groundwater level. According to the field observations and geological exploration results, a small-scale landslide was observed on January 10, 2016, after excavation along XiaoMo highway in Yunnan Province. A numerical model in actual size using GeoStudio software based on this typical red bed engineering slope was established in this study. Back analyses and laboratory tests were used to obtain the mechanical parameters of the geomaterial inside the slope. The historic rainfall data of Mengla County from July to September in 2016 was utilized as the flux boundary in analyzing the seepage variation features and the stability of the engineering slope in the rainy season. One major tension crack was set in the shallow region of the silty clay according to the geology survey to perform the disturbance of excavation on the geomorphology of the slope. Attempts were made to establish the anisotropic permeability of the crack induced by the complex fillings, and differences in the hydraulic response between the cracking and completed slope during the rainfall process were discussed. The result shows that the factor of safety of the slope without crack before the rainfall is 1.076, and the slope is considered in the state of the critical limit equilibrium, which is in accordance with the previous state of the slope under real conditions. The pore water pressure variations of the monitor points in the shallow region of the completed slope present close compliance with the rainfall intensity subjected to different rainfall patterns, which also controls the distribution of the plastic zone in the slope after rainfall. The comparisons in the seepage field and plastic zone between the cracking and completed slope reveal that the crack can shorten the infiltration path effectively, and the higher the permeability coefficient in the vertical direction is, the larger the pore water pressure increasing zone is and the higher the underground water level is, which should be paid more attention in highway constructions.

Analysis of Mechanical Properties and Slope Stability of Red Bed Soft Rock: A Case Study in Xinjiang Irrigation Diversion Channel

“…Reservoirs and water diversion engineering channels are widely distributed and often need to run through the red-bed distribution area. Te red-bed soft rock is prone to cracks, swelling, slope collapse, and other problems [6,7], afecting the normal water delivery and operation safety of the water channel. Under long-term operation conditions, the sediment denuded from the channel sidewall is prone to siltation along the way through the fow transportation in the channel, which seriously leads to the elevation of the channel bottom, the increase of the channel width, and the reduction of the berm [8][9][10].…”

Soil nutrients determine leaf traits and above-ground biomass in the tropical cloud forest of Hainan Island

“…According to Dietze et al (2014), soluble sugar can be used as a direct carbon source for transportation and plant use. Thus, soluble sugar indicates the plant's ability to buffer environmental fluctuations (Zhang et al, 2021) by reflecting the balance between carbon intake and consumption (Würth et al, 2005). In the same way, soluble sugars influence the growth and development of plant tissue, both generative and vegetative.…”

Dynamic risk assessment of slope stability of homogeneous earth-rock dam under action of multiple hazards

“…Rainfall is also an important factor affecting the stability of dam slopes, 17 which increases the water content of the soil surface and reduces the strength parameters of the surface soil, thereby reducing the slope safety factor of the dam. Zhang et al 18 and Elkamhawy et al 19 found that during rainstorm, the stability of the slope decreases, the rainfall infiltration leads to the decrease of soil shear strength, through monitoring the positive pore water pressure and horizontal earth pressure of soil under rainfall conditions. 20,21 Besides, Huang et al 22 performed a numerical simulation to calculate the stability coefficient of the Three Gorges Project affected by reservoir water level fluctuations and rainstorms.…”