Geographically, northern Iraq, specifically on the border between Iraq, Turkey, and Iran, is considered a complex geological area consisting of different types of rocks, including sedimentary, igneous, and metamorphic. The height of the mountains in these areas ranges between 2,000 and 4,000 meters. Recently, many changes occurred in the region as a result of natural disasters such as earthquakes, random drilling of wells, and the rapid development of multi-story buildings, which led to many modifications in the geology of the Kurdistan Region. In order to construct any tunnel, the geological plan and profiles should be formed by evaluating the site investigations, and the boreholes should be drilled through the tunnel route. Accurate investigations about the geological structure and nature of the ground can be conducted during the excavation. Also, essential laboratory tests are done on core samples extracted from boreholes along the tunnel. The behaviors of the geological and geotechnical situation of the tunnel are presented, focused on the inlet of the tunnel. This work relied on previous geological investigation surveys that were conducted in the region and related to this subject, the results of geological field mapping and laboratory tests, and the geological and geotechnical parameters used for the design and construction of the tunnel. The best excavation method that can be used in this area is the New Austrian Tunneling Method (NATM), based on the economic and area conditions.

Design and construction of twin tunnels are influenced by several points such as distance between the two tunnels, position and construction procedure, etc. Tunnel failures has an influence on surface and sub-surface structure. The failures mostly result from geotechnical and geological conditions, design and suitable construction methods. For tunnel stability, it is very important to understand the distributions of various stresses on tunnels. Displaying the results of static and dynamic analysis after construction were concentrated at (stress and displacement). A series of three-dimensional numerical analyses were carried out to evaluate the behavior of position and construction process of twin tunnels. New geotechnical software called MIDAS GTS NX (v. 2015) has been used to model the twin tunnel in different cases. Collecting different data from several researches respect to this topic subjected by previous authors. Linear elastic behavior is the familiar way to analyses and modeling tunnel which assumed that the material is linear, isotropic and homogeneous. On other hand, first tunnel (e.g. upper tunnel) has been constructed firstly then they start to construct the second one. In special case, both of twin tunnels can be excavated at the same time. The aim of this study is to evaluate the effect of position and construction procedure on the tunnel structure and the surrounding ground, comparing with the previous work.

The major design parameters related in tunnel engineering are loads, tunnel dimensions, geological and geotechnical properties of the ground surrounding the tunnel, which controls stresses and deformation of this underground structure. The effects of static loads during tunneling with shield Tunnel Boring Machine (TBM) on the rock mass and segmental concrete lining are considered. Applied static loads are (self-weight, drilling or excavation pressure, jack thrust, shield external pressure and segment external pressure). A comparison of the results of maximum total displacement and principal stresses of soft rock for different tunnel diameters including (D = 4, 6, 8, 10, 12 and 14 m) is performed. Tunnel lining of a circle tunnel were assumed to behave in a simple linear elastic way. Rock mass is assumed to be Isotropic, homogeneous and elastic rock in this modelling. The numerical analysis has been simulated and evaluated for each models separately. The thickness of tunnel lining for all models was assumed as 30 cm. The main concluding points of this study are to analyze the behaviour of tunnel lining and the surrounding rock under static loads during the construction processes using numerical modeling.

Most of the researchers are constructed twin tunnels as horizontal, in some cases the twin tunnel verti-cally overlapping lined horizontal tunnels are constructed in order to avoid the other structure as like pile foundations. This paper illustrates the 3D numerical model by using software MIDAS GTS NX which is established to investigate the tunnel simulation in order to highlight the effect of static and dynamic load on the behaviour of tunnel lining. There are several points which have effect on the results of de-sign as like distance between the two tunnels, the stiffness and density of the lining material and ground, the character and magnitude of seismic loading, etc. Inner diameter of analysed tunnel is marked of D = 6 m. Thickness of concrete lining corresponds of t = 0.3 m. The depth of the top part of tunnel from the ground level is of 10D m below the surface of the ground. Distance of the twin tunnel centres is of 3D m. Response Spectrum of UBC (1997) is used as seismic response spectrum, were undertaken to com-pare the results in the displacement and stresses acting on the grouting/segment to find the quantity of deformation through tunnelling, finally to approve that the applied dynamic stress is not negligible for underground structure, but it is less dangerous in comparison with the others.

According to recent studies and observed failures of underground structures, many researchers have addressed the design and construction of tunnel lining against static/dynamic loads and earthquake vibration to get the safety of these structures. Therefore this paper includes the study of the behavior of tunnel lining due to static and dynamic loads. Inner diameter of tunnel is D m. Concrete lining of thickness 0.3 m. The depth of the tunnel centre line from the ground level is 10 D below the surface of the ground, the twin tunnel centre are 3D. After tunnel model is created in the software MIDAS GTS NX, the model is run to analyze the tunnel stability and deformation in static and dynamic conditions by calculating the value of each mesh node based on 3D finite element method and were undertaken to investigate the seismic tunnel response conditions to compare the results in the displacement, stresses, forces and bending moments acting on the tunnel lining. Due to the application of the static load the stress–strain state around the tunnel periphery is changed, the primary stress state is disrupted and the potential of instability increases, otherwise the result shows that the applied dynamic stress is not negligible for underground structure, but it is less dangerous in comparison with the others.

Several loads are occurring in tunnel construction process that can be divided into number of stages. In each of these stage, the tunnel lining and surrounding soil affected by different loads which can cause the deformation and instable. This paper illustrates the use of MIDAS GTS NX to investigate the tunnel’s simulation in order to highlight the effect of static and dynamic load on the behaviour of tunnel to compare this response expressed in terms of displacement and stresses acting on the tunnel and ground. Main tunnel is located in the ground having uniform property throughout its extent, connecting gallery is located perpendicular to the main tunnel, the shotcrete and rock bolts for each tunnel will be installed.

One of the important tasks in mechanized tunneling using tunnel boring machines is to determine the required face pressure ensuring its stabilization. For the solution of this task various methods can be used. Analytical calculations to determine the required stabilizing face pressure are mainly based on limit equilibrium methods and plasticity theory. Although numer-ical methods (finite element method, etc.) to determine the tunnel face pressure facilitate the modelling of this problem with more general calculation assumptions (inhomogeneous envi-ronment, etc.) as compared with the above analytical methods, the creation of the model and the actual calculation are more time consuming. The paper presents the comparison of face pres-sure values obtained from analytical models of different authors, and from the numerical model. The paper concludes by presenting the resulting comparative charts for various computational methods and an analysis of obtained results.

A full three-dimensional (3D) numerical model using the finite element software program MIDAS GTS NX is established to investigate the tunnel’s simulation in order to highlight the effect of enter force and elements of construction procedure on the behaviour of segmental tunnel lining. It is important noticing that shallow tunnels suffer higher damage compared to deep structures. Many numerical analyses were carried out in order to verify and compare the stresses, normal forces and bending moments acting in the final tunnel lining according with the seismic design. During the Shield TBM excavation, it is assumed that the excavation pressure and the Jack thrust are applied on the shield excavation face. The Shield external pressure and segment external pressure are applied around that face. This work study, a three-dimensional Finite Element Method was prepared to simulate the static and dynamic behavior of circular tunnels, were undertaken to investigate the seismic tunnel response conditions to compare the results with the stresses, forces and bending moments acting in the final tunnel lining according with the seismic design, dynamic for different tunnels diameter and different rock types (soft, moderately and hard rock) under the same condition.

The aim of this paper is to analyse the effects of static and dynamic loads on the stability and deformation of circle tunnels reliance to Response Spectrum. Most of researchers explain that shallow tunnels suffer higher damage compared to deep structures. During the shield Tuunel Boring Machin (TBM), it is assumed that the excavation pressure and jack thrust are applied on the shield excavation; the shield external pressure and segment external pressure are applied around that face. There is on layer for different ground materials (soft, moderate and hard rock) under the same condition, at the same depth of tunnel under ground surface by 20 m from the external tunnel diameter. A full 3D numerical model using the finite element software MIDAS GTS NX is established, the model is run to analyse the tunnel stability and deformation in static and dynamic conditions by calculating the value of each mesh node based on 3D finite element method to investigate the comparison in different tunnel diameter and different modulus of elasticity response conditions to compare the results in the displacement, stresses, forces and bending moments acting in the tunnel lining. This work has two cases (different types of tunnel diameters and different value of ground elastic modulus). Due to the application of the static load the stress-strain state around the tunnel periphery is changed, the primary stress state is disrupted and the potential of instability increases, otherwise the result show that the applied dynamic loads is not negligible on underground structure, but it is less dangerous in comparison with the others.

According to recent studies and observed failures of underground structures many researchers have been addressed the design and construction of tunnel lining against static/dynamic loads and earthquake vibration to get the safety of these structures, therefore this paper includes the study of the behavior of tunnel lining due to static and dynamic loads . Inner diameter of tunnel is D m. Concrete lining of thickness 0.3 m. The depth of the tunnel center line from the ground level is 10 D below the surface of the ground, the twin tunnel centre are 3D. After tunnel model is created in the software MIDAS GTS NX, the model is run to analyze the tunnel stability and deformation in static and dynamic conditions by calculated the value of each mesh node based on 3D finite element method were undertaken to investigate the seismic tunnel response conditions to compare the results in the displacement, stresses, forces and bending moments acting on the tunnel lining. Due to the application of the static load the stress-strain state around the tunnel periphery is changed, the primary stress state is disrupted and the potential of instability increases, otherwise the result show that the applied dynamic stress is not negligible for underground structure, but it is less dangerous in comparison with the others.

Gali-Zakho tunnel is located on the highway in Duhok city-Iraqi Kurdistan, this city is the border between Kurdistan-Iraq and Turkey, involves design and construction of a dual carriageway road with two individual tubes with a total length of 3.604 Km. Tectonically; Iraq was located in a relatively active seismic zone at the tectonically active northern and eastern boundaries of the Arabian Plate. Earthquakes in this seismic zone can be cause significant infrastructure damage, especially in the eastern part of North-East (NE) Iraq. The project area is located on 3rd degree earthquake zone according to the earthquake zone. The East Anatolian Fault Zone (EAFZ) which constituted the scene of intensive earthquake activities is 260 Km northwest (NE) of the project area. Therefore, possible earthquake movements that may affect the project area in the future are determined through an earthquake risk analysis with considering the maximum moment magnitude of (M =8.5 on EAFZ).Second important tectonic element is the Bitlis-Zagros trust fault zone, for the seismic risk analysis (M = 7.5) moment magnitude is considered. Seismic risk analysis shall be considered in accordance with the relevant regulations while designing. Horizontal ground acceleration coefficient shall be taken as Ao = 0.14 g for the tunnel design and 0.07 g for the earth works. Structural analysis has been done by means of SAP 2000 and using numerical analysis technique Phase2 “Finite Element Analysis for Excavations” and the most critical results of moment, shear and axial force diagrams has been displayed as analysis results.

One of the important tasks in mechanized tunneling using tunnel boring machines is to determine the required face pressure ensuring its stabilization. When addressing this task, it is possible to use various methods, which differ in their mathematical essence, calculation assumptions, the degree of conservatism of results, required computing time and calculation efficiency, which is a very important factor, particularly when flexibly solving practical problems. Analytical calculations to determine the required stabilizing face pressure mainly rely on limit equilibrium methods and plasticity theory. The “lower bound theory” allows obtaining a statically acceptable solution which, however, is quite conservative. On the other hand, the “upper bound theory” allows obtaining kinematically acceptable non-conservative solution. Although numerical methods (finite element method, etc.) to determine the tunnel face pressure allow modelling this problem with more general calculation assumptions (inhomogeneous environment, etc.) as compared with the above analytical methods, the creation of the model and the actual calculation are more time consuming. The paper presents the comparison of the face pressure values obtained from analytical models of different authors, and from the numerical model, created by the authors of this paper in MIDAS GTS. The paper concludes by presenting the resulting comparative charts for various computational methods and analysing the results.

This paper presents the results of an experimental investigation of the using of carbon fiber reinforced polymer (CFRP) to enhance the high strength reinforced concrete (RC) deep beam in case of creating a circular cutout throughout its web. A set of 5 specimens were grouped and investigated to evaluate the structural behavior in terms of shear strength capacity and deflection. The specimens were 1200mm long with rectangular cross-section of 100x500mm. Two symmetric circular cutouts of 150mm diameter were made at mid-point of each shear span. CFRP strips were installed around the cutouts in three different configurations in order to enhance the cutout zone. The results of this experimental work showed that the diagonal configuration of CFRP strips around the cutout was the best one, as the ultimate shear strength ratio with respect to control solid beam was 0.97, while it was 0.86 for control beam with cutouts. A significant positive effect was observed on the deflection for the beams that enhanced with CFRP strips. Also, CFRP sheet oriented diagonally around cutout was the most appropriate for reducing the deflection.

The contribution presents the results of 3D-stochastic modelling of slab-subsoil interaction. The cooperation between the centric loaded concrete foundation slab (square shape, dimension 2 m x 2 m, thickness 0.1 m) has been modeled as a contact problem using software MIDAS GTS (based on the finite element method). To take into account the stochastic character of the soil characteristics the stochastic simulation Latin Hypercube Sampling method was used. Four input stochastic parameters of soil were considered - elastic modulus, unit weight, friction angle and cohesion. From the contact modelling viewpoint two variants were modelled – first variant neglected the interface elements on the contact, in the second one the interface elements were involved into the model. The contribution presents the 90% confidence interval for the settlement in the centre of the upper surface of the slab and for the contact stresses below the slab also. The results of experimental measurements were used to the calibration of the model.

Most of researchers explain that shallow tunnels suffer higher damage compared to deep structures. Many numerical analyses were carried out in order to verify and compare the stresses, forces and bending moments acting on tunnel lining according with the seismic design. After tunnel modelling in MIDAS GTS NX to investigate the tunnel simulation in order to highlight the effect of static and dynamic load on the behaviour of tunnel lining for different cases and calculated the value of each mesh node based on 3D finite element method to simulate the effect of earthquake on tunnel were undertaken to investigate the comparison in different tunnel diameter and different modulus of elasticity response conditions to compare the results in the displacement , maximum principle stress and minimum principle stress acting in the tunnel lining. Design response spectrum of UBC (1997) is used as seismic response spectrum. Due to the application of the static load the stress-strain state around the tunnel periphery is changed, the primary stress state is disrupted and the potential of instability increases, otherwise the result show that the applied dynamic stress is not negligible for underground structure, but it is less dangerous in comparison with the others.