Experimental study on seismic response and progressive failure characteristics of bedding rock slopes

Bedding rock slopes are common geological features in nature that are prone to failure under strong earthquakes. Their failures induce catastrophic landslides and form barrier lakes, posing severe threats to people’s lives and property. Based on the similarity criteria, a bedding rock slope model with a length of3 m, a width of 0.8 m, and a height of 1.6 m was constructed to facilitate large-scale shaking table tests.The results showed that with the increase of vibration time, the natural frequency of the model slope decreased, but the damping ratio increased. Damage to the rock mass structure altered the dynamic characteristics of the slope;therefore, amplification of the acceleration was found to be nonlinear and uneven. Furthermore, the acceleration was amplified nonlinearly with the increase of slope elevation along the slope surface and the vertical section, and the maximum acceleration amplification factor(AAF) occurred at the slope crest. Before visible deformation, the AAF increased with increasing shaking intensity;however, it decreased with increasing shaking intensity after obvious deformation. The slope was likely to slide along the bedding planes at a shallow depth below the slope surface. The upper part of the slope mainly experienced a tensile-shear effect, whereas the lower part suffered a compressive-shear force. The progressive failure process of the model slope can be divided into four stages, and the dislocated rock mass can be summarized into three zones. The testing data provide a good explanation of the dynamic behavior of the rock slope when subjected to an earthquake and may serve as a helpful reference in implementing antiseismic measures for earthquake-induced landslides.

A Comprehensive Method for the Risk Assessment of Ground Fissures:Case Study of the Eastern Weihe Basin

Ground fissures are influenced by the coupling of geological factors and human activi-ties.They threaten the safety of infrastructure and restrict town planning in many areas in China.One of the area most severely affected by ground fissures is the Weihe Basin in North China,which has the most extensive distribution of ground fissures and all the elements that control their occurrence,pro-viding an ideal study area for the study of ground fissures.In this study,we took the eastern Weihe Ba-sin as the study area and determined the distribution and hazard characteristics of ground fissures via field investigation.Based on the analytic hierarchy process,we propose a multi-level,comprehensive method for evaluating the hazards of ground fissures.This method considers the geological back-ground,development status,and triggering factors of ground fissures,including all nine currently known assessment indices of ground fissures.We used judgment matrices to rank the constructed ground fissure assessment index system at the single and total levels and quantified the nine assessment indices of ground fissures according to the field survey data.Finally,we plotted the ground fissure risk zoning map and evaluated the ground fissure risk at the study area.Our findings indicated that the proposed method could facilitate ground fissure hazard assessment and prediction and provide support for hazard prevention and urban/rural planning.

Formation Mechanism of Ground Fissures Originated from the Hanging Wall of Normal Fault:A Case in Fen-Wei Basin,China

This paper takes Fen-Wei Basin(FWB)as a case to study the ground fissures controlled by normal fault.Based on the field investigation,geophysical exploration,drilling,GNSS data and numerical calculation,the characteristics and mechanism of ground fissures originated from the hanging wall of normal faults are revealed.The results show that the distribution of ground fissures in the hanging wall and heading wall of the active faults is not uniform.Ground fissures are mostly distributed in the hanging wall of active faults and show a linear distribution on the surface,their strike is consistent with the fault,mainly characterized by vertical offset and horizontal tension.Ground fissures destroy the farmland and building foundation through which they pass and cause the rupture or displacement.In profile section,the ground fissure shows the characteristics of normal faults and dislocates the strata,and is connected with the underlying faults.Numerical analysis shows that the vertical displacement of normal fault activity in hanging wall is much larger than that in heading wall,which is the reason that tectonic ground fissures mainly originate from hanging wall.The range of dangerous area of ground fissures is controlled by the depth of fault,the strength of the ground fissures disaster is mainly controlled by the activity of fault.The formation of the ground fissures originated from the hanging wall of the fault experienced three stages:the main fault activity stage,the secondary fault activity stage and the fissure formation stage.