Introduction
Underground structures have become an essential part of the metro
cities. Construction of the underground structures especially tunnels
for the efficient movement of humans and goods has resulted in the
investment of a massive amount of money in the underground space.
Therefore, underground structures especially rock tunnel has been an
active area of research since mid-nineteenth century. Manouchehrian and
Cai carried out a finite element study for static and dynamic loading
for a circular tunnel. They have used finite element software
Abaqus/Explicit and Python scripting for the study. They have shown the
importance of using a finite element analysis for case histories are
useful for the rockburst phenomenon due to the presence of
discontinuities [1]. Mishra et al., [2] carried out the study
for tunnels when subjected to static and dynamic loading using finite
element software Abaqus/Explicit. The analysis has been carried out for
different geomaterials, and it has been concluded that the settlement of
the tunnel crown has a direct relationship with the friction angle.
Mishra et al., [3]concluded that the effect of load in deformation
of tunnel reduces as the distance of loading position increases. They
have calculated different zones of deformations for different rock mass
for shallow rock tunnels. Bobet carried out the study under static and
seismic loading for the effect of pore water pressure on the stability
of tunnel support. It has been concluded that the racking deformation
and the flexibility of the tunnel are directly related [4].
Furthermore, the underground tunnels have been subjected to dynamic
loads such as seismic loads, impact loads, blast loads and other types
of loading. Stability of tunnels under blast loading has attracted
several researchers in recent decades [5]–[13]. Moreover,
Matsagar has carried out the comparative study for composite sandwich
panel and non-sandwich panel for blast loading. They have utilised
finite element analysis for comparison of different materials and
concluded that cenosphere aluminium alloy syntactic foams found to be
the superior material for the reduction in the damage caused by the
blast load [14][15]. Jaini and Feng have studied the response of
reinforced cement concrete (RCC) slab using computational modelling.
They have carried out a finite discrete element analysis for the damage
analysis of RCC slab. It has been concluded from the study that the use
of both positive and negative phase of blast response may give more
realistic results [16].
Further, blast study has also been carried out for the response of
concrete pavement slab by Luccioni and Luege [17]. They have
considered three different explosive charge weights and the stand-off
distance of explosive remains constant as 5m. Based on experimental,
numerical and limit analysis, they have proposed an equation that
relates the diameter of crater and the explosive charge. The behaviour
of spherical explosive charge has been discussed by Brode [18]. When
a blast event occurs, there has been the presence of vibrations in
addition to heating effect of blast. Hence, Berta has carried out the
study on the vibrations induced in tunnel by the blast loading [19].
Jingbo et al., [20] had studied the blast wave propagation in the
tunnel by using finite element software LS-DYNA. Chen and Zhao have
utilized UDEC modeling for the study of blast wave propagation in the
jointed rockmass [21]. Choi et al., have used AUTODYN software for
the 3D nonlinear dynamic analysis of tunnel subjected to internal blast
loading. They have used Coupled-Eulerian-Lagrangian modeling to
simulating the blast response[22]. Buonsanti and Leonardi had
carried out the study on rail tunnel subjected to internal blast loading
using ANSYS code [23]
The present paper deals with the response of a rock tunnel when
subjected to internal blast loading using finite element software
Abaqus/Explicit [24], [25]. The Mohr-Coulomb constitutive
material model has been considered for the Quartzite rock. In the
present study, the effect of the weight of explosive charge has been
carried out. Also, the response of rock tunnel under varying thickness
of tunnel lining has been incorporated. The four different overburden
depths are also considered.