Field Investigation and Finite Element Analysis of Landslide-Triggering Factors of a Cut Slope Composed of Granite Residual Soil: A Case Study of Chongtou Town, Lishui City, China

The red beds that are widely distributed in hilly areas in eastern Sichuan Province are inevitable rock and soil masses in engineering construction. In order to obtain a larger building area, engineering slope cutting is quite common in red bed hilly areas. Engineering slope cutting destroys the inherent stability of a slope and causes geological disasters. In order to practice the concept of sustainable development and explore ways to develop and utilize land resources reasonably and reduce the possibility of geological disasters caused by engineering slope cutting, this paper took the slope cutting sites caused by rural housing construction in the red bed area of Wanyuan City as research objects. The internal and external factors affecting the stability of the cut slopes were summarized through a field investigation, and two typical slopes were selected for analysis. Sampling and indoor tests were conducted to obtain the geotechnical parameters. Geo Studio software (2018 R2) was employed to establish numerical models, simulate the stress and strain distributions, and compute stability coefficients under different slope cutting conditions at the same time. Based on field investigations and numerical simulations, the three main failure modes of shallow landslides caused by slope cutting were summarized, and the evolution process of slope landform accelerated by slope cutting activities was deduced. In an engineering application, the functional relationship between the cutting height and the stability coefficient was fitted. It was found that the critical cut height values of soil slope were 6.3 m, 6.2 m, 5.2 m, and 2.6 m at slope of 10°, 20°, 30° and 40°, respectively; the critical cut height values of rock–soil mixed slope were 9.3 m, 6.5 m, 5.9 m, and 2.2 m at slope of 10°, 20°, 30° and 40°, respectively. The research findings can be used to prevent and manage the hazards caused by slope cutting in this study area.

Section: Introductionmentioning

confidence: 94%

Study on the Stability of Cut Slopes Caused by Rural Housing Construction in Red Bed Areas: A Case Study of Wanyuan City, China

He,

Dong,

et al. 2024

“…It has been recognized that uncertainty has a significant influence on the stability of geological structures such as slopes. However, in the stability analysis of unsaturated soil slope, the stratum was usually considered to be deterministic in the past [28][29][30][31][32][33][34][35]. Recently, increasing attention has been paid to the unsaturated slope stability analysis considering the spatial variability of soil properties [36][37][38][39][40][41][42].…”

Section: Introductionmentioning

confidence: 99%

Stability of Unsaturated Soil Slope Considering Stratigraphic Uncertainty

Cao

Wan

Li³

2023

Stratigraphic uncertainty is widely present in nature, but it has not been well considered in the stability analysis of unsaturated soil slopes in the past. In this study, the stability of the unsaturated soil slope is evaluated based on borehole data considering stratigraphic uncertainty. Firstly, an enhanced coupled Markov chain model is used to simulate stratigraphic uncertainty. Then, a finite element algorithm for automatically calculating the safety factor (FS) and the average groundwater table (AGT) of the unsaturated soil slope is developed. At last, a hypothetical slope located in the stratum from Perth, West Australia is analyzed using the proposed algorithm under different borehole schemes. The results show that with the increase in the borehole number, the statistics of FS and AGT will not monotonically increase or decrease. But the trend is that the mean values of FS and AGT gradually approach and eventually converge to the real values, and the standard deviations of FS and AGT decrease. There is a linear relationship between the standard deviation of FS (or AGT) and the average information entropy. The FS and AGT are negatively correlated considering stratigraphic uncertainty.

“…The mechanical properties and stability of GRS are significantly affected by water. Soil disintegration, which refers to the phenomenon of soil fragmentation, breaking, and separation or weakening of its strength in hydrostatic water, is closely related to the resistance of soil to water intrusion and is a critical evaluative indicator of soil erosion [1,[6][7][8][9][10][11]. The prominent disintegration behavior of GRS is responsible for the apparent collapsing erosion of the granite weathering zone, resulting in severe soil erosion and environmental damage, as well as natural geohazards such as landslide and mudslide disasters [12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

“…Some scholars have used the quantitative testing method to evaluate GRS disintegration characteristics and its influential factors, including internal factors (e.g., dry density, initial moisture content, degrees of weathering, structure, and mineral composition) and external factors (e.g., temperature, pH, and dry-wet cycles) [1,[6][7][8][9][10][11][12]15,16,21]. Scholars agree that the initial moisture content significantly affects the disintegration characteristics of GRS.…”

Section: Introductionmentioning

confidence: 99%

Disintegration Characteristics of Remolded Granite Residual Soil with Different Moisture Contents

Chen,

Zhou,

et al. 2023

Granite residual soil (GRS) has prominent disintegration characteristics which have induced various geological disasters and engineering problems. The initial moisture content is believed to affect the disintegration of GRS significantly. To explore the effects of the initial moisture content on the soil disintegration characteristics and disintegration mechanism, disintegration tests were performed on remolded GRS with different initial moisture contents via the balance method, and the quantitative disintegration indices were corrected, considering the effects of water-absorption weight gain, in combination with a parallel water-absorption test. The disintegration characteristics and mechanism were thoroughly investigated, starting with the disintegration process curves and disintegration morphology, and combined with strength theory, X-ray diffraction (XRD) and X-ray fluorescence (XRF), the matric suction test, and the triaxial shear test. The results are as follows. (1) The corrected method improves the accuracy of the quantitative disintegration evaluation. (2) During the two disintegration stages, the forms of disintegration are dispersive fragmentation and progressive or block separation, and the soil matric suction and weakening of intergranular joining forces, respectively, are the drivers of disintegration. The first stage is usually completed within 1.5–2 min, and the disintegration ratio is usually within 20%. (3) The trends of change within the disintegration during the two stages show opposite water-content-dependent modes, and the soil samples with lower moisture contents have better water stability and slower disintegration in the second stage. The average disintegration rate of the soil with a moisture content of 24.4% in the first and second stages was approximately 1/5 and 13 times, respectively, that of the soil with a moisture content of 6.1%; these values can be rendered as 0.049%/s and 0.82%/s, respectively. The results provide some theoretical references for soil and water conservation and engineering applications in the GRS field.