الفهرس 
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Abstract
Tunnels and shafts are versatile structures that are used for solving many problems all over the world. Tunnels are versatile underground passageways that may be used for many
purposes. Nowadays, many countries depend on tunnels to solve their problems with the
transportation process. For that reason, the world is witnessing a great leap in the technology
of the design and construction of tunnels. Shafts are vertical openings usually used as annexed
structures for tunnels for some safety issues. Shafts are used especially for long tunnels as an
economical natural ventilation system and an emergency egress. They are also used as
entrances to the tunnel’s working face to accelerate the construction process.
The intersection between tunnels and shafts is a challenging construction issue. This 3-
dimensional problem needs a thorough knowledge of the geological and geotechnical
conditions of the surrounding soil to be properly studied. The purpose of this thesis is to study
the behavior of tunnel-shaft connections under static loading and make a parametric analysis
for the same problem.
Line 3 of Greater Cairo is extended from El-Salam on the east to Imbaba and Cairo
University on the west. It consists of various stations with different types, i.e.: underground,
at-grade, and elevated stations. For safety and ventilation issues, the tunnel between any two
consecutive underground stations is chosen to be intersected with a vertical shaft. Tunnel-shaft
connection 17A between Kolleyet El-Banat and Al-Ahram stations, from Greater Cairo Metro
Line 3, Phase 2, was used as the case study of this research.
Numerical modeling is used as the analysis method for this problem. The finite element
method (FEM) is chosen, which is the most common numerical analysis method. Full details
of the procedures and components of FEM are presented in this study.
Midas GTS NX 2019 package was used for implementing the numerical simulation of
our problem. Data from National Authority for Tunnels (NAT) was obtained for the FEM
model. from this data, detailed parameters used for numerical simulation for soil, tunnel, shaft,
internal slabs, connection and loads, and boundary conditions are obtained and presented.
Analysis stages for such a problem, as constructed in reality, are also stated. Results from the
model were verified using settlement monitoring results from actual data.
The settlement at ground level (GL), the settlement around the connection, soil stresses
around the connection, and internal forces at the connection are the outputs that were discussed
in this study. Firstly, the base model representing the actual field data was performed, and the
results were discussed. Then, a parametric study was performed on the base model by changing
a definite parameter each time, and the effect of changing that parameter on all outputs was
discussed. Three parameters were chosen for this parametric study: The first one is the
groundwater level, the second is the construction sequence and the third is volume loss ratio.
Base model results showed that settlement at ground level and around the connection
was increased in the first stages, and breaking the connection between the tunnel and shaft
showed no effect on settlement and heave values. Soil stresses around the connection also had their maximum values in the first stages, and breaking the connection didn’t affect the results.
Concerning internal forces at connection, normal forces had relatively small values at all
chosen nodes, and after connection execution, these values of normal force were significantly
increased and continued to increase for subsequent stages, however shear forces and bending
moments had relatively small values, compared to normal forces.
Performing the parametric study using the GWL parameter showed that the base model
and dry model with no GW had nearly the same results for all outputs, but the model with high
GWL, 1 m below the surface, had lower values, except for settlement at GL, which had equal
values. For settlement around the connection, the high-water level model had smaller values
than the two other models, and settlement values were approximately 10% smaller than the
values of the base model. For the effective stress of soil around the connection, the high-water
level model values were about 55% smaller than values of the base model, and shear stress
values in the ZX direction were nearly between 55% and 60% of base model values. Normal
forces around the connection for the high GWL model in two directions were much lower than
the other models, and their values were approximately between 60-70% of values when
compared to base model values, but shear forces and bending moments had generally small
values.
Secondly, the construction sequence effect was discussed, by executing four models,
by changing the order of the “break the connection” stage in each one. Changing construction
sequence have nearly no effect on the settlement at GL, the settlement around the connection,
and solid stresses around the connection, and also have no effect on internal forces for all
chosen nodes around the connection, except for the two nodes at the bottom sides of the
opening between tunnel and shaft. For those two nodes, the maximum values for normal forces
and bending moments are not affected by changing construction sequence, but they have
different trends in the subsequent stages. Shear force for those two nodes has its maximum
values in sequences 1 and 2, due to breaking the connection before installing internal slabs
inside the shaft, so sequences 3 and 4 were preferable as a construction sequence to sequences
1 and 2.
Lastly, the effect of changing volume loss was discussed by executing three models
with different volume loss percentages, 0% “base model”, 0.3% and 0.5%. Increasing volume
loss resulted in increasing the settlement at ground level and around the connection that for
every 0.1% increase in volume loss, the settlement values increased by 100%. For solid
stresses, the increase in volume loss resulted in increasing effective and shear stresses except
for effective stress in the ZZ direction that was decreased. Finally, all internal force at the
connection increased due to increase in volume loss. For shear force and bending moment, the
values of the base model were very low and could be neglectable, but by adding volume loss,
shear force and bending moment values increased, and became considerable
Generally, the tunnel-shaft connection must be cared for in the design and construction
process and be the focus of more studies.