Research Projects

Rockfall is one of the most frequent threats in mountainous regions, which results in a series of damages and sometimes a secondary disaster following an earthquake. In hilly areas, this situation affects the livelihood of the people as roads often get blocked and become unusable, causing disruption to transportation, loss of property, and more importantly, loss of lives. Rockfall damage makes it more challenging to rescue injured individuals and restore disaster zones. Presently, rock shed structures have gained popularity as a form of passive protection against rockfalls, as they are designed to withstand the impact forces of falling rocks while safeguarding roads and other infrastructure. Rock shed structures are very much effective in the areas of extreme rockfall hazard where slope stabilization is very costly. Rock shed structures are used beneath the very steep high slopes where frequent rockfall occurs. Additionally, these structures require minimal maintenance. Rock shed structures are built using frames topped with a flat or inclined concrete slab or shell or tunnel type that is covered by cushioning materials. The cushioning material is placed on the rock shed structures to distribute the impact forces and absorb energy. In the absence of a protective cushion layer, rock boulder impacts cause significant damage to the steel-reinforced concrete structures, rapidly releasing substantial energy within a very short period of time. The cushioning material should be reasonably priced and suitable for construction. Generally, sand or gravels are used as cushioning materials. It is important to note that while a thicker cushion can enhance its resistance to high-impact energy, but increasing the thickness of the soil cushion also raises dead loads and construction costs. The use of geosynthetic reinforcements within the cushion may reduce the required thickness of the cushion and dead load on the rock shed structures. Geosynthetic-reinforced soil offer huge potential for protective applications due to their affordability and fast construction. Therefore, the present investigation will make use of both planar geogrid reinforcement and three-dimensional geocells reinforcement as protective cushion layer on rock sheds under rockfall impact. The main objective of the present research is to study the performance of unreinforced and geosynthetic-reinforced protective layers on rock shed structures under impact loading. The results will be measured in terms of acceleration, earth pressure developed in the protective layer (or on the rock shed structures), and strain developed in the rock shed structure and reinforcements. To achieve the objectives, a series of field tests will be conducted on unreinforced and geogrid or geocell-reinforced sand/gravel cushion layer under different heights of fall of the impactor. Numerical analysis will be performed using finite element software ABAQUS/Explicit. After validating the numerical model, parametric study will be conducted to provide the design guidelines (such as optimum thickness of the cushion layer, optimum number of the planer reinforcement layer, selection of appropriate geocell properties, stress or load acting on rock shed structures with geosynthetic-reinforced cushion) for the reinforced cushion layer over rock shed structures under rockfall impact. Field tests and validation of the numerical model will be done λ = 1/6 of the prototype conditions, but for the parametric study, prototype dimensions or impact load/impact energy will be considered. The design guidelines obtained from the present study will help practicing engineers to design such structures as rockfall protective measures.