Sand–Tire Shred Mixture Performance in Controlling Surface Explosion Hazards That Affect Underground Structures

Blasting is an unavoidable activity in geotechnical engineering, road and tunnel construction, and mining and quarrying. However, this activity can expose the environment to various hazards that are challenging to control and, at the same time, critical for the safety of site workers, equipment, and surrounding structures. This research aims to evaluate the ability of sand–tire shred mixtures to reduce peak blast pressure, which is the leading cause of damage to underground structures under surface explosion. ABAQUS software is used to model the material behavior under explosion and is validated using the results of previous studies and an empirical equation. Different scenarios are created by using mixture layers with different thicknesses (2, 4, and 6 m) and tire shred contents (10%, 20%, and 30%) that are subjected to various surface explosion charges (100, 500, 1000, and 5000 kg). The thickness of the mixture layer is found to be directly related to the dissipation of explosion energy. However, the percentage of the rubber content in the mixture is only significant in reducing peak blast pressure when a thick enough mixture layer is used. The results confirm the adequate performance of the correctly chosen sand–tire shred mixtures in reducing peak blast pressure and protecting the underground structure from surface explosion hazards.

Theoretical and Numerical Analysis of Blasting Pressure of Cylindrical Shells under Internal Explosive Loading

Cylindrical shells are principal structural elements that are used for many purposes, such as offshore, sub-marine, and airborne structures. The nonlinear mechanics model of internal blast loading was established to predict the dynamic blast pressure of cylindrical shells. However, due to the complexity of the nonlinear mechanical model, the solution process is time-consuming. In this study, the nonlinear mechanics model of internal blast loading is linearized, and the dynamic blast pressure of cylindrical shells is solved. First, a mechanical model of cylindrical shells subjected to internal blast loading is proposed. To simplify the calculation, the internal blast loading is reduced to linearly uniform variations. Second, according to the stress function method, the dynamic blast pressure equation of cylindrical shells subjected to blast loading is derived. Third, the calculated results are compared with those of the finite element method (FEM) under different durations of dynamic pressure pulse. Finally, to reduce the errors, the dynamic blast pressure equation is further optimized. The results demonstrate that the optimized equation is in good agreement with the FEM, and is feasible to linearize the internal blast loading of cylindrical shells.

Numerical and Experimental Protective Performance Evaluation of Sacrificial Member Effects on the Protective Structures

Principal objectives of the protective design are on protecting life, property, facility, system device and operations by developing protective design measures that reduce threat level and vulnerability while enhancing structural resilience. Protective design procedure against blast hazard would be accomplished with the threat identification, risk-based assessment, and designing the members and structures based on the proper design requirements. Considerable necessity before the protective design is to find out the various measures reducing the blast effect such as security measures, architectural configuration, and mitigation schemes without any structural strengthening the structure itself. This paper addresses the mitigation scheme to reduce the blast overpressure in general, and then a specific barrier type is introduced as sacrificial structures with the performance verification. The general schemes to reduce the blast pressure by installing barriers is mainly using RC type structures which have typical shapes and sizes. This barrier type has advantages both on installing easiness and cost. In the barrier type sacrificial wall structure, instead of using the normal RC structures, enhanced-cement concrete and composites are useful to improve protective performance and scabbing of the back surface of the RC walls. A series of the wall type RC barriers are modeled and fabricated to investigate and verify blast pressure migration and protective performance based on theoretical and numerical analysis.

Evaluation of internal blast resistance of bi-directionally prestressed concrete tubular structure according to ANFO explosive charge weight

When extreme loading from an internal is applied to prestressed concrete (PSC) structures, serious property damage and human casualties may occur. However, existing designs for PSC structures such as prestressed concrete containment vessels (PCCV) do not include features to protect the structure from the blasts. Therefore, the internal blast resistance capacity of PSC structures is evaluated by internal blast tests on bi-directional PSC tubular members. The goal of the study was to obtain the structural behavior data from an internal detonation. The ANFO charges were detonated at the center of the mid-span of the tube specimen with a standoff distance of 1,000 mm. The data acquired included blast pressure, deflection, strain, crack pattern, and prestressing loss. The data are used derive the equations to calculate the required internal blast charge weight to fail a real-scale PCCV and to calibrate a commercial simulation program to be used for internal blast simulations.