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Excavation-induced ground movements and the resulting damages to adjacent structures and facilities is a source of concern for excavation projects in urban areas. The concern will be even higher if the adjacent structure is old or has low strength parameters like masonry building. Frame distortion and crack generation are predictors of building damage resulted from excavation-induced ground movements, which pose challenges to projects involving excavations. This study is aimed to investigate the relation between excavation-induced ground movements and damage probability of buildings in excavation affected distance. The main focus of this paper is on masonry buildings and excavations stabilized using soil nail wall method. To achieve this pu
Human growing demand for energy and in recent decades for clean and renewable energy, leading to the development of wind farms inshore areas and have moved to offshore areas to achieve more production. Noticed that wind farms are a series of large, expensive & same structures, their foundations are important and it’s necessary to minimize the probability of failure all of them. Many wind turbines are founded on large piles called monopiles. In European countries particularly in offshore areas, dominant environmental loading on monopiles is the wave. But some of the pioneer countries in wind energy development, such as China, India and the United States are highly seismic areas. Following the occurrence of natural events of wave and earthq
Arash Tunnel is an 1870 m underground urban tunnel project, which is under construction, in Tehran by New Austrian Tunneling Method (NATM). Due to the existence of different entrances and exits in its traffic scheme, it comprises various traffic lane sections like one-lane, two-lane, three-lane, twin two-lane and two-story two-lane sections. In this paper, we are going to declare our experiences during the design and the construction of the most complex part of this project, a twin tunnel. Valiasr tunnel is composed of two connected initial and two discrete adjacent final lining tubes. Based on a comparison between the monitoring data and the numerical simulation results, the contractor is requested to use additional supports or alter cons
Underground structures and facilities constitute the underlying and infrastructural part of modern urbanization and are used for a wide range of applications, including urban underground railroad and urban road tunnels, silos etc. Underground structure’s construction method depends on such factors as the ground conditions, the ground water conditions, the tunnel span and the buried depth. The cut and cover method is an engineering technique for underground construction with low buried depth in urban areas. Furthermore, some urban underground facilities have been constructed in areas with risk of seismic activity which be resistant to both static and seismic loads. Therefore, seismic response of such shallow tunnels which are usually const
A suction-controlled ring device has been developed to continuously measure the coefficient of lateral soil pressure in deformable unsaturated soil samples from the at-rest to the active condition under application of increasing vertical pressure and controlled matric suction. The device incorporates a thin aluminum specimen ring equipped with horizontal strain gages for recording the lateral soil strains. In addition, a sensor recording water volume changes is utilized to continuously monitor the degree of saturation of the soil sample during tests. The matric suction within the soil texture is controlled using the axis translation technique. In order to verify the performance of the ring device, twenty suction-controlled tests under appli
The bearing capacity of a pile group mostly depends on parameters of the soil shear strength affected by the soil-water characteristics, especially in unsaturated soils. The soil shear strength is entirely affected by hydraulic stresses in unsaturated soil, such as precipitation and evaporation. Further, the bearing capacity of the pile installed on unsaturated soil depends on hydraulic stresses applied to the soil. Furthermore, slope vicinity may cause a severe decline in the pile bearing capacity. The present study aimed to investigate a pile group in unsaturated soil adjacent to a slope and analyzed the effect of the rainfall on the soil strength parameters. Thus, a numerical study has been performed using a finite difference software,i.
The current study is aimed at investigating the basic soil behavior involved in a TBM-EPB excavation and the capability of the Modify Cam Clay (MCC) model is verified for the analysis of the soil settlement in cohesive soils. Tunnel excavation in urban areas can engender considerable ground movements, which is known as one of the complicated issues that may have negative effects on the extant structures. In this paper, the construction of the second line of the Mashhad metro is considered as a case study. Each section of the ground was modeled by two constitutive models, namely MCC and Mohr-Coulomb (MC). Afterwards, the results of numerical analyses and monitoring data were compared with each other. In addition, real parameters of soil, suc
A micromechanical continuum model based on mechanics of tensile microcracks, is presented for brittle failure of rock containing randomly distributed microcracks. The proposed model describes both the mechanical response of rock and microcracks geometry evolution under compression. By generalizing the results obtained from the analysis of one single microcrack and including the effects of interaction among neighboring microcracks, this model for brittle rock under compression is derived. In order to illustrate the predictive capability of the proposed model for mechanical properties of rock and microcracks geometry evolution under compression, the model is applied to Inada granite. Numerical results are compared with experimental data from
In order to increase the productivity of extraction of hydrocarbons reservoirs, the well is usually drilled in the direction of the minimum horizontal in situ stress and hydraulic fractures simultaneously initiate and propagate perpendicular/transverse to the wellbore. The last decade, more than 10,000 horizontal wells per year have been bored and hydraulically fractured, with up to a hundred hydraulic fractures placed in the horizontal segment of the well. The well is therefor stimulated in stages, with one stage consisting of a single pumping operation aimed at initiating and propagating simultaneously typically between3-8 cracks spaced about 10–30 m apart. When, the fluid pressure is applied on the surface of the fracture, the crack ca
Tunnels are vital substructures that are strongly influenced by the surrounding soil, especially when using the New Austrian Tunneling Method (NATM) in which the soil surrounding the tunnel displaces under part of the applied load and the remaining load is borne by the tunnel initial lining. Displacement monitoring is of great importance in this method and designers should monitor data during construction in addition to a choosing an initial design based on primary soil parameters. The method should be a performance-based approach that is required to meet a target. This paper reports on a case study on an urban twin tunnel constructed using NATM. The construction method is compatible with existing geological conditions and space constraints
This research aims to declare a case study on a twin tunnel constructed by New Austrian Tunneling Method. The twin tunnel is sketched with connected initial linings and separate final linings, due to dimension and obstacles restrictions. Three scenarios of excavation were numerically modeled in order to reduce settlement. The first scenario comprises entire excavation and installation of the initial lining of each section in order. The second scenario simulates the effect of keeping Center Cross Diaphragm during excavation till the entire construction of initial lining. The third scenario evaluates the effect of final lining construction for a section before entire initial stabilization of another. Numerical results show that the third scen
Tensile strength which is an important parameter of the rock for engineering applications is difficult to measure directly through physical experiment (ie uniaxial tensile test). Therefore, indirect experimental methods such as Brazilian test have been taken into consideration and some relations have been proposed in order to obtain the tensile strength for rocks indirectly. In this research, to calculate numerically the tensile strength for granitic rocks, Particle Flow Code in three-dimension (PFC3D) software were used. First, uniaxial compression tests were simulated and the tensile strength was determined for Inada granite (from a quarry in Kasama, Ibaraki, Japan). Then, by simulating Brazilian test condition for Inada granite, the tens
To investigate the effect of tunnel existence on the ramp stability, two models have been simulated. The case study is a part of Arash tunnel project constructed in Tehran, Iran. The first model contains construction of tunnel, conduit, and ramp, respectively, while in the second model (without tunnel) after conduit implementation, ramp is constructed. This article is aimed to discuss the displacements induced in ramp walls, and ground settlements due to existence of the adjacent tunnel, and supporting elements in two numerical cases. Numerical results demonstrate that the displacement of ramp walls, and ground settlements have increased in the tunnel existed model. Also the location of maximum displacement of ramp walls and ground surface
The under passing tunnels are strongly influenced by the soils around. There are some complexities in the specification of real soil behavior, owing to the fact that lots of uncertainties exist in soil properties, and additionally, inappropriate soil constitutive models. Such mentioned factors may cause incompatible settlements in numerical analysis with the obtained values in actual construction. This paper aims to report a case study on a specific tunnel constructed by NATM. The tunnel has a depth of 11.4 m, height of 12.2 m, and width of 14.4 m with 2.5 lanes. The numerical modeling was based on a 2D finite element program. The soil material behavior was modeled by hardening soil model. According to the field observations, the numerical
Any investigative approach towards rock behavior will necessitate inherent deficiencies such as pores and cracks to be taken into consideration. One of the methodologies employed to study cracked rock is to consider an equivalent continuum as for the domain with defects which will lend flexibility to experimental and numerical schemes due to its seamless effects on the constitutive relationships, hence reducing computational costs as well as experimental restraints in the laboratory. A case in point in such approach is the crack tensor model which is based upon the idea to represent cracks’ size, orientation, and number density as one single entity through which proper geometric characterization of the in situ rock is carried out. Followi
In the process of hydraulic fracture, various physical parameters such as; viscosity, inertia of fluid and toughness of rock do not influence the fracture propagation identically, and it is probable that one or more of the parameters be more pronounced. Therefore, it may persuade one special regime which is named base on dissipation of energy. In an impermeable rock, the two limiting regimes can be identified with the dominance of one or the other of the two energy dissipation mechanisms corresponding to extending the fracture in the rock and to flow of viscous fluid in the fracture, respectively. In the viscosity-dominated regime, dissipation in extending the fracture in the rock is negligible compared to the dissipation in the viscous flu