The surrounding conditions of tunnel lining may change
during the investment period which leads to a redistribution of
forces acting on the tunnel lining and perhaps gives new forces are not taken into account during the design. The behavior of the
tunnel should be analyzed for the new conditions and assess its performance through the stages of investment.
In this paper, a case study of Alsafkon tunnel which is one of
the Syrian Railway deep tunnels is regarded. The lining of this
tunnel suffers from cracks, leakage, and other defects.
To analyze the behavior of the tunnel lining, it has been
modeled using the finite element method software Phase for five cases that represent the investment conditions experienced by the tunnel from its construction to date. It was found that the lining cracks appear from the third phase which represents the case of immersion of the tunnel by the underground water. The formation of a weak lens adjacent to the tunnel detected by geo radar plays also an important role in the cracking of the lining of the tunnel.
The results of numerical analysis were in correspondence with the current situation of the tunnel in terms of distributed cracks places in the concrete lining. The study showed also the improvement importance of the lens properties to avoid the total fall down of the tunnel.
Tunnels are usually considered as important and costly constructions and
therefore it is very necessary to estimate their performance and analyze
their structural behavior to maintain their safety in order to ensure their
reliability and performan
ce during their hypothetical life.
In this issue we reviewed the situation of Syrian railway tunnels on Aleppo –
Lattakia axis from the field observations which show that these tunnel
linings are cracked.
The numerical method, which is known as Distinct Element Method, was
used in the analysis of cracked lining. This method performs modeling of
discontinuous systems. We focused in this study on the concrete type
through elasticity modulus and lining thickness. The result analysis shows
that the effects of cracks modify the distribution of stresses and
displacements in the lining. This modification is related to concrete elasticity
modulus and mechanical crack characteristics.
This paper presents and analyses the results of 2D and
3D numerical simulation conducted for the performance prediction
of TBM tunneling in clay soil.
