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Measuring stiffness of soils in situ
Published in Fusao Oka, Akira Murakami, Ryosuke Uzuoka, Sayuri Kimoto, Computer Methods and Recent Advances in Geomechanics, 2014
Fusao Oka, Akira Murakami, Ryosuke Uzuoka, Sayuri Kimoto
The rapid increase of urban activities in mountainous areas encouraged more attention to be given to the mitigation of threats caused by natural hazards such as rockfalls and debris flows. Due to their high flow velocity and impact forces, long runout distance and poor temporal predictability, granular flows have been classified as one of the most hazardous landslides (Jakob & Hungr 2005). However, their hazard can be mitigated by the use of protection structures similar in principle to rockfall barriers (Guasti et al. 2011). Such structures are either retaining walls (Kishi et al. 2000) or flexible structures made of nets (Nicot et al. 2001). The estimation of total impact force exerted by granular flows on such structures is an important factor in their design. Such a force generally varies with slope angle, thickness of the flowing material and velocity at the moment of the impact.
Present understanding and predictive capability of the stability conditions for very high rock cuts
Published in Giovanni Barla, Prediction and Performance in Rock Mechanics and Rock Engineering, 2000
In broad terms rockfall protection can be divided either into active face protection (rock reinforcement and netting over) or passive protection involving toe and possibly intermediate catch structures or control drape nets. The principal concerns relate to the slope height and geometry which will in turn dictate the likely trajectories and energy of rockfall events. To maximise safety, active or control systems that limit kinetic energy generation are normally preferred.
Providing perfect numerical simulations of flexible rockfall protection systems
Published in António S. Cardoso, José L. Borges, Pedro A. Costa, António T. Gomes, José C. Marques, Castorina S. Vieira, Numerical Methods in Geotechnical Engineering IX, 2018
Flexible rockfall protection systems are an efficient and effective way to protect buildings and infrastructure from this considerable natural hazard. Rockfall protection systems usually consist of steel nets which are mounted in the field using steel ropes and posts that in turn are anchored to the ground. Special energy absorbing elements between the steel ropes and the anchors provide high deformation capabilities and act as a form of load limiting device.
Dynamic analysis of rock fall impact for a cantilever rock shed with geofoam cushion
Published in European Journal of Environmental and Civil Engineering, 2023
Ozgur Lutfi Ertugrul, Abduh Kiwanuka
The design of rockfall protection measures is generally carried out considering the topography of site, discontinuities and the mechanical characteristics of the surficial rocks, the vegetation on the slope and the underlying structure which is prone to rockfall risk. Advancements in materials science contributed to the effectiveness of the protection barriers. The kinetic energy levels that can be withstood by protection structures are ever increasing. One of the permanent alternatives of rockfall protection can be considered as rockfall sheds. They are widely used to protect transportation facilities located at the base of narrow valleys with steep rock cuts. These alternatives are generally suitable to protect structures for valley portions with relatively confined rockfall zones. Due to impact type loading acting on rock sheds, different impact absorbing materials are being installed on top of roof slab. Gravel and sand are preferred traditionally; however, they increase the overburden on the structure and the initial deformations of the rock shed structure. Labiouse et al. (1996) indicates that a proper rock shed structure should consist of a load carrying structure and a soil cushion for energy absorption. Current state of the art for the efficient design of rock sheds requires proper quantification of fundamental rock fall characteristics including impact forces and penetration depths (Jacquemound, 1999). It should also be mentioned that the geometry of the falling rocks, on overall mechanisms involved during impact, can be identified as an important part of rock fall impact analyses.
Demarcation of probable failure zones based on SMR and kinematic analysis
Published in Geomatics, Natural Hazards and Risk, 2019
S. Kumar, H. K. Pandey, P. K Singh, K. Venkatesh
Rockfall refers to the movement of loose blocks along the slopes under the influence of gravity (Keskin 2013; Singh et al. 2013). The movement of blocks can be through free fall, roll, slide, bounce or a combination of these and the entire activity is controlled by the surface profile of the slope face and the rock material involved. On a vertical slope, movement of loose blocks is mainly by free fall but with gradual decrease in slope angle, the movement of the blocks transforms to roll, bounce and slide. However, sliding of a block is generally observed in the initial and final stages of a typical rockfall event and if the slope gradient does not change, the sliding block will lose all its kinetic energy due to friction and finally stop (Bozzolo and Pamini 1986; Dorren 2003).
Multi-Scenario Analysis of Rockfall Hazard for a Historical Vaulted Masonry Building in Sumela Monastery
Published in International Journal of Architectural Heritage, 2022
Mohammad Manzoor Nasery, Suleyman Istemihan Cosgun, Bayram Ali Temel
Rockfall is a natural disaster in the mountainous areas caused by physical, chemical, or biological separation of rock blocks from the bedrock, which falls down slope under the influence of gravity with a high speed and impact energy that can cause substantial damage to the infrastructure and human life in the surrounding area. Sumela monastery faces rockfall hazards because of its unique location at the slope of the Zigana Mountain. Rockfall is a destructive factor for any structure as it exerts impact loading on structures, which can lead to heavy damage and even demolition. In order to investigate the dangers of rockfall on the slope, the massive rock, which was above the complex was examined by using the industrial climbers’ techniques. Examinations showed that there are currently pending rock fragments and the exposed rock surfaces are dangerous. There are some free blocks in the parts extending at the foot of the forest, and there are large and small pieces of free stones in the forest spills. It was also determined that due to the intense water leaks from the cracks, there were material losses in some places and these situations were a risk to the monastery and visitors. Therefore, in 2015, the monastery complex was closed to the visitors to carry out large-scale cleaning, placing security barriers, protective cover, and reinforcement works. Following the restoration works, it is planned to carry out the procedures for the monastery to be registered in the UNESCO World Cultural Heritage List. The monastery was opened for visitors in 2021. The view of the massive rock above the Sumela Monastery complex is given in Figure 1.