Key Takeaways & Executive Findings
- •• Cracks at the slope crest tend to propagate in shear mode with an initiation angle of approximately 8°, while toe cracks may propagate in either tensile or shear mode. • Shear crack initiation angle at the crest increases with slope angle, crack position parameter, and crack length parameter, but decreases with crack inclination angle, with a maximum variation of about 30°. • Tensile crack initiation angle at the toe decreases with slope angle, crack inclination angle, and crack length parameter, while the influence of crack position parameter is minor, with maximum changes ranging from 25° to 60°. • Theoretical predictions of crack propagation modes and directions align well with transparent soil model test results, validating the analytical stress field formula.
Abstract
The stability of rock slopes is frequently controlled by the initiation and propagation of inherent dominant cracks. This study systematically investigated these processes in valley slopes by combining fracture-mechanics analysis with transparent soil model tests. An analytical expression for the stress field at the dominant crack tip was derived from the slope stress distribution by superposing the corresponding stress intensity factors (SIFs). The theoretical predictions were then validated against observations from transparent soil model tests. The influences of slope angle (b), crack inclination angle (a), crack position parameter (b), and crack length parameter (l) on crack initiation and propagation were quantified. The results indicated that: (1) cracks at the slope crest tended to propagate in shear mode, and the shear crack initiation angle (hs) was approximately 8°. Cracks at the slope toe might propagate in either tensile or shear mode. (2) hs at the slope crest increased with b, b, and l, and decreased with a. The maximum change in hs induced by the considered parameters was approximately 30°. (3) The tensile crack initiation angle (ht) at the slope toe decreased with b, a, and l, while the influence of b was comparatively minor. The maximum change in ht caused by individual parameters ranged approximately from 25° to 60°. Predicted crack propagation modes and directions showed good agreement with experimental results. These findings provide theoretical guidance for stability assessments of valley slopes controlled by dominant crack propagation.
1. Introduction
Crustal stress concentrations, unloading zones, and associated tension-shear fracture zones commonly develop in valley rock slopes as a result of tectonics, valley downcutting, and prolonged weathering [1,2]. Valley-slope evolution frequently produces high-inclination tensile cracks at the slope crest and low-inclination shear cracks at the slope toe due to unloading. External disturbances—such as earthquakes, surface-water erosion, and anthropogenic activities—can drive propagation of these cracks, ultimately triggering slope instability [3–5]. The integrity of the rock bridge connecting the high-inclination crack at the crest and the low-inclination crack at the toe has been identified as the principal control on slope stability [6–8]. Therefore, these dominant cracks are crucial factors influencing valley slope stability and are essential for preventing large-scale engineering disasters.
Understanding the initiation and propagation behaviors of these dominant cracks is crucial for assessing rock-slope failure. Numerous studies have investigated crack initiation, propagation, and coalescence using laboratory experiments [9,10] and numerical simulations [11,12]. For example, Li et al. [13] numerically explored the effects of crack inclination angle and loading condition on crack initiation and propagation. Huang et al. [14] investigated tension-shear strength and hybrid fracture in sandstone through laboratory experiments and numerical simulations. Leng et al. [15] examined dominant crack propagation and internal deformation of the valley slope via transparent soil model tests, providing valuable insights into the mechanisms of slope failure.
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Xianlun Leng, Chuan Wang, Chengtang Wang, Zhanrong Zhang, Haibin Wang, Lan Cui, Kun Fang (2025). Theoretical investigation on the initiation and propagation behavior of dominant cracks in valley slopes. SinoTechIntel Verified Research. https://doi.org/10.1016/j.ijmst.2025.11.002
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Frequently Asked Questions
What is the main focus of this study?
The study focuses on the theoretical and experimental investigation of the initiation and propagation behavior of dominant cracks in valley slopes, combining fracture mechanics analysis with transparent soil model tests.
How were the theoretical predictions validated?
The theoretical predictions were validated against observations from transparent soil model tests, showing good agreement in crack propagation modes and directions.
What are the key parameters influencing crack initiation angles?
The key parameters include slope angle (b), crack inclination angle (a), crack position parameter (b), and crack length parameter (l). Their effects on shear and tensile crack initiation angles were quantified.
What are the practical implications of this research?
The findings provide theoretical guidance for stability assessments of valley slopes controlled by dominant crack propagation, aiding in the prevention of large-scale engineering disasters.
What is the significance of the crack initiation angles?
Crack initiation angles determine the direction of crack propagation, which is critical for predicting slope failure mechanisms and assessing stability.
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