scholarly journals A review on the performance of the underground tunnels against blast loading

2021 ◽  
Vol 4 (1) ◽  
pp. 1-17
Author(s):  
Kasilingam Senthil ◽  
Muskaan Sethi ◽  
Loizos Pelecanos
Keyword(s):  
Lateral Displacement ◽  
Blast Loading ◽  
Blast Waves ◽  
Tunnel Lining ◽  
Standoff Distance ◽  
Blast Load ◽  
Charge Weight ◽  
Burial Depth ◽  
Tunnel Wall ◽  
Tunneling System

The tunneling system has become an important part of the present infrastructure system in all over the world. Therefore, it has become important to ensure the safety of the tunnels against any type of man-made blasting activities or other accidental blasting occurrence. In order to evaluate the performance of the tunnels against blast loading, a detailed review is carried out. Based on the review in the last couple of decades, the various parameters such as tunnel lining materials, tunnel shapes, tunnel lining thickness, tunnel burial depth, charge weight and standoff distance are high influences on the performance of underground tunnels against blast loading. It was observed that the tunnel roof and the tunnel wall center are most vulnerable to the blast loads. Also, it was found that more of the tunnel lining thickness results in lesser deformation at the tunnel roof and the tunnel wall center. The increase in the burial depth of the tunnel would reduce the extent of damage to the tunnel caused by effects of surface blast loading. The stiffness and strength of the ground media may be enhanced against the effects of blast loading by grouting measures. The studies revealed that the lining materials possessing blast waves absorbing properties can be best suited to be used in tunnel linings. Further, it was observed that more damage was caused to the tunnels due to the magnitude of the charge weight. An increase in the blast load causes a significant increase in the fracture area, residual stress and lateral displacement caused to the tunnel by the action of blast load. The standoff distance of the blast load from the tunnel also plays a significant role in the damage of the tunnel. More is the distance between the charge and the tunnel, lesser damage caused to the tunnels. In addition to that, the lining thickness was predicted and the trend was calibrated and fitted logarithmically with the available results. Based on the observation from the literature, it is concluded that the use of a single lining material in the tunnel against blast loading was studied predominantly in the couple of decades. Further, the performance of the tunnels in combination of different tunnel lining materials against blast loading was found limited. The influence of barriers to save the underground tunnels against blast loading was found limited.

scholarly journals Blast Loading and Its Effects on Building

2021 ◽  
Vol 9 (10) ◽  
pp. 1068-1078
Author(s):  
Mohini Chaurasiya
Keyword(s):  
Human Life ◽  
Blast Loading ◽  
Shear Walls ◽  
Shear Wall ◽  
Blast Waves ◽  
Blast Load ◽  
Front Face ◽  
Charge Weight ◽  
Explosion Pressure ◽  
Building Model

Abstract: Terrorist assaults have become more common in recent years. Their main purpose is to destroy important structures such as areas of defense, hospitals, schools, buildings. Due to the explosion, high pressure is generated and the blast time is also very short, but it can damage the structure from outside and inside. Which can cause a lot of damage to human life. There has an influence on the nation's economy. Like the earthquake and wind load, the blast load should also be designed, keeping in mind the important structures that have to be avoided from the explosion. In this research paper, six story R.C.C. Structures exposed to explosion loads are analyzed. We study the effect on the building by changing the weight of the explosive and the distance between the explosion source and the building. The IS 4991-1968 code has been used to calculate the parameters of the explosion pressure waves. The program ETabs 2019 has been used to analyze the effect of blast load. The structure has been modified by providing shear walls to reduce excessive displacement due to blast loading on the building. The results of the analysis are compared after adding the shear wall with the general building model. The result was that after the addition of the shear wall, the effect of blast loading is greatly reduced. Keywords: Blast phenomena, Standoff distance, detonation charge weight (TNT), Front face pressure, Side face pressure, ETABS, RCC, Blast waves, explosive effects, Story Displacement, Storey Drift, Overturning Moment, Shear wall.

scholarly journals Dynamic Response of RC Panel with and Without Openings Subjected To Blast Loading

2019 ◽  
Vol 8 (10) ◽  
pp. 2535-2549
Keyword(s):  
Reinforced Concrete ◽  
Dynamic Response ◽  
Blast Loading ◽  
Blast Load ◽  
Front Face ◽  
Charge Weight ◽  
Plasticity Model ◽  
Rear Face ◽  
Peak Displacement ◽  
Concrete Damaged Plasticity

The dynamic response of reinforced concrete (RC) panels without and with different configuration of opening under blast load scenario is investigated in the present study. The numerical simulations were carried out using finite element method with ABAQUS application. The concrete behavior under blast loading was modelled using Concrete damaged plasticity model. The material parameters for concrete damaged plasticity model were determined using methodology proposed by [14]. The parametric study was carried out using variation in blast load due to different charge weight. It was observed that the peak displacement increases with increase in blast load. It was also observed that at lower blast load, failure of reinforced concrete panel was initiated by cracking at rear face of panel but as the blast load increases the RC panel was failed by combination of crushing of front face of panel along with cracking of rear face. It was observed that for the given blast load, the RC panel without opening is less affected by crushing failure as compared to RC panel with opening configuration studied. It was also observed that the RC panel with circular opening at center is stiffer than other opening configuration and observed to have stable structural performance against the blast load studied.

A Re-Look Into Modified Scaled Distance Regression for Prediction of Blast-Induced Ground Vibration

2021 ◽  
Vol 12 (1) ◽  
pp. 22-39
Author(s):  
Saha Dauji
Keyword(s):  
Performance Measures ◽  
Ground Vibration ◽  
Blast Waves ◽  
Charge Weight ◽  
Mining Activities ◽  
Weight Estimation ◽  
Industrial Practice ◽  
Scaled Distance ◽  
Conservative Values ◽  
Distance Approach

Underground blasts are conducted for deep excavations, tunneling, or mining activities. Scaled distance regression analysis is performed in industry to estimate peak particle velocity from charge weight and distance. For addressing the uncertainties in estimating safe charge weight for controlled blasting, 95% confidence expression is generally used. For addressing inaccuracies arising from superimposition of blast waves in multi-hole blasting when using attenuation equation developed from single-hole blast data, a modified approach was proposed in literature. This article presents comparisons to establish that industrial practice of scaled distance regression would be as satisfactory as the proposed modified approach, when various performance measures (including parsimony) are considered together. Furthermore, industrial practice of using 95% confidence expression generated from sufficient data (say, 40 numbers) would result in safe charge weight estimation, whereas modified scaled distance approach (mean expression) could still result in few non-conservative values.

Mitigation strategies of underground tunnels against blast loading

2021 ◽  
pp. 204141962110380
Author(s):  
Senthil Kasilingam ◽  
Muskaan Sethi ◽  
Loizos Pelecanos ◽  
Narinder K Gupta
Keyword(s):  
Blast Loading ◽  
Plain Concrete ◽  
Fiber Reinforced Concrete ◽  
Mitigation Strategies ◽  
Critical Parameters ◽  
Small Scale ◽  
Burial Depth ◽  
Inelastic Behavior ◽  
Steel Fiber Reinforced Concrete ◽  
Finite Element Software

An evaluation of mitigation strategies of underground tunnels against explosions is important to the society. Therefore, a small scale tunnel was modeled against blast loading using finite element software ABAQUS. The inelastic behavior of concrete and steel bar has been incorporated through concrete damage plasticity model and Johnson-cook models respectively, available in ABAQUS. The Drucker-Prager model as well as acoustic infinite medium have been used to model the damage behavior of soil and tunnel respectively. The simulated results thus obtained from the present study were compared with the experimental results available in the literature and found in good agreement. Further, the simulations were carried to predict the damage intensity in tunnel in terms of acceleration, impulse velocity, displacement, and Mises stresses. There are many parameters which were taken into consideration to assess the mitigation strategies for the underground tunnels. The critical parameters include the influence of tunnel shapes, lining materials, lining thickness, burial depth of the tunnels, inclusion of a barrier in between the blast source-the tunnel and layered configuration of tunnel lining, and were considered to evaluate the mitigation strategy. It was concluded that the square shape of tunnel was most vulnerable as compared to circular and U-shaped tunnels. It was also concluded that plain concrete monolithic lining as well as layered configuration consisting of Dytherm foam layer between Steel Fiber reinforced Concrete layers, was found to be more vulnerable among the chosen lining materials. Also, the thickness of lining and burial depth of the tunnel found to be a significant role against blast loading.

scholarly journals Sandwich Panels with Polymeric Foam Cores Exposed to Blast Loading: An Experimental and Numerical Investigation

2020 ◽  
Vol 10 (24) ◽  
pp. 9061
Author(s):  
Kristoffer Aune Brekken ◽  
Aase Reyes ◽  
Torodd Berstad ◽  
Magnus Langseth ◽  
Tore Børvik
Keyword(s):  
Shock Tube ◽  
Numerical Models ◽  
Sandwich Panels ◽  
Blast Loading ◽  
Experimental Tests ◽  
Quantitative Agreement ◽  
Low Velocity Impact ◽  
Blast Load ◽  
Low Velocity ◽  
Skin Deformation

Sandwich panels have proven to be excellent energy absorbents. Such panels may be used as a protective structure in, for example, façades subjected to explosions. In this study, the dynamic response of sandwich structures subjected to blast loading has been investigated both experimentally and numerically, utilizing a shock tube facility. Sandwich panels made of aluminium skins and a core of extruded polystyrene (XPS) with different densities were subjected to various blast load intensities. Low-velocity impact tests on XPS samples were also conducted for validation and calibration of a viscoplastic extension of the Deshpande-Fleck crushable foam model. The experimental results revealed a significant increase in blast load mitigation for sandwich panels compared to skins without a foam core, and that the back-skin deformation and the core compression correlated with the foam density. Numerical models of the shock tube tests were created using LS-DYNA, incorporating the new viscoplastic formulation of the foam material. The numerical models were able to capture the trends observed in the experimental tests, and good quantitative agreement between the experimental and predicted responses was in general obtained. One aim of this study is to provide high-precision experimental data, combined with a validated numerical modelling strategy, that can be used in simulation-based optimisation of sandwich panels exposed to blast loading.

Comparative Study of the Dynamic Response of Different Materials Subjected to Compressed Gas Blast Loading

2011 ◽  
Author(s):  
Brandon J. Hinz ◽  
Matthew V. Grimm ◽  
Karim H. Muci-Ku¨chler ◽  
Shawn M. Walsh
Keyword(s):  
Dynamic Response ◽  
High Speed ◽  
Mechanical Response ◽  
Blast Loading ◽  
Test Sample ◽  
Blast Waves ◽  
Small Scale ◽  
Acceleration Time Histories ◽  
Compressed Gas ◽  
Brain Tissue Damage

Understanding the dynamic response of materials under blast and impact loading is of interest for both military and civilian applications. In the case of blast loading, the mitigation characteristics of materials employed in personal protective equipment (PPE) is of particular importance. Without adequate protection, exposure of the head to blast waves may result in or contribute to brain tissue damage leading to traumatic brain injury (TBI). The development of simple but representative laboratory experiments that can be used to study the mechanical response of different materials and/or material combinations to blast loading could be very useful for the design of PPE such as helmets. This paper presents a basic experimental setup that can be conveniently used to perform such studies using small scale compressed gas blasts. An open end shock tube is employed to generate the blasts used to load flat plate samples placed in a special rigid holder. Acceleration time histories at selected locations in the sample are used to generate data to compare the dynamic response and blast mitigation effectiveness of different specimens. High speed schlieren video is used to correlate the arrival of the shock wave and air flow that follows with the motion of the test sample.

Interaction of Blast Load on AASHTO Girder Bridge

2016 ◽  
Vol 857 ◽  
pp. 131-135
Author(s):  
G. Nikhil ◽  
N.I. Narayanan
Keyword(s):  
Highway Bridges ◽  
Standoff Distance ◽  
Blast Load ◽  
Structural Elements ◽  
Maximum Displacement ◽  
Explicit Finite Element ◽  
Analysis And Design ◽  
Finite Element Software ◽  
Girder Bridge ◽  
Blast Resistant Design

Guidelines of blast resistant design for AASHTO girder bridges have not taken up much importance on researches. As the transportation infrastructure mainly bridges are highly vulnerable for bomb attack, they must be designed to resist it. The analysis and design of bridges subjected to blast load requires a detailed understanding of blast propagation and its dynamic effects on various structural elements. The response of bridge components subjected to blast load is carried out using Abaqus explicit finite element software. The bridge is modeled on the basis of AASHTO-LRFD bridge design specification for highway bridges. Blast load has been introduced on different critical location of the bridge to understand their effects on various structural elements and extent of damage. A thorough parametric study varying standoff distance and TNT mass is done to understand their importance in developing a blast resistant design for AASHTO Girder Bridge. The study concludes that the value of maximum displacement decreases with the increase in standoff distance.

Characteristics of Free Air Blast Loading Due to Simultaneously Detonated Multiple Charges

2014 ◽  
Vol 14 (04) ◽  
pp. 1450002 ◽  
Author(s):  
Nimasha Weerasingha Mohottige ◽  
Chengqing Wu ◽  
Hong Hao
Keyword(s):  
Numerical Simulation ◽  
Pressure Ratio ◽  
Mesh Size ◽  
Blast Load ◽  
Charge Weight ◽  
Single Charge ◽  
Air Blast ◽  
Scaled Distance ◽  
Free Air ◽  
Blast Resistant Design

Extensive research has been conducted to investigate the characteristics of blast load due to single charge explosion, including numerical simulations and experimental blast tests in both unconfined and confined environments. Further, available guidelines for blast resistant design such as UFC-3-340-02 (2008) and ASCE 59-11 (2011) provide details to predict blast loads on a structure subjected to single charge explosion. However, blast load characteristics due to multiple charge explosions are poorly discussed in available literature. In this paper, commercially available Hydrocode, AUTODYN is calibrated for single charge explosions. Based on a comparison between numerical simulation and UFC prediction, correction factors for peak reflected pressure and positive reflected impulse as a function of charge weight, scaled distance and mesh size of the numerical model are proposed to minimize the errors in simulations. The calibrated AUTODYN model is then used to conduct parametric studies to investigate the effects of charge weight, scaled distance, number of charges and distance between the charges on the characteristics of free air blast load due to simultaneous detonated multiple charges. Numerical simulation results are used to derive analytical formulas for predictions of peak reflected pressure ratio and positive reflected impulse ratio between single and multiple explosions. The discussion is made on characteristics of free air blast load due to simultaneous detonated multiple charges.

scholarly journals Analysis of the Response of a One-Storey One-Bay Steel Frame to Blast

2016 ◽  
Vol 2016 ◽  
pp. 1-11
Author(s):  
Rupert G. Williams ◽  
William A. Wilson ◽  
Reisa Dookeeram
Keyword(s):  
Analytical Study ◽  
Considerable Increase ◽  
Plastic Region ◽  
Blast Loading ◽  
Building Design ◽  
Charge Weight ◽  
Building Structures ◽  
Single Degree Of Freedom ◽  
Blast Design ◽  
Plane Frame

In recent years, there has been a considerable increase in perceived risks of blast loading attacks or similar incidents on structures. Blast design is therefore a necessary aspect of the design for building structures globally and as such building design must adapt accordingly. Presented herein is an attempt to determine the numerical response of a seismically designed single-degree-of-freedom (SDOF) structure to blast loading. The SDOF model in the form of a portal frame was designed to withstand a typical seismic occurrence in Northern Trinidad. Blast loads caused by applying a 500 kg charge weight of TNT at standoff distances of 45 m, 33 m, and 20 m were then applied to the model. The blast loading on the frame was determined using empirical methods. The analytical study showed that the seismically designed SDOF plane frame model entered the plastic region during the application of the blast load occurring up to the critical standoff distance.

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