Vahed Ghiasi

Evaluation of tunnels under squeezing rock condition

Purpose – The purpose of this study is to evaluate the methods employed for classifying and quantifying the potential of squeezing in tunnels. Along with the empirical and semi‐empirical approaches presently available in order to anticipate the potential of squeezing tunnel problems, the squeezing potential of Karaj water transfer tunnel and North West Tunnel Convey (NWTC) tunnels (Lot 2), located in Iran, are evaluated and presented. Those two case studies have an interesting geology profile and parameters to identify and then evaluate the squeezing potential.Design/methodology/approach – In recent years, there has been an increasing interest in the tunnel construction. This paper describes the squeezing behavior of poor rock mass associated with deformability and strength properties. In Karaj water transfer tunnel, there are eight lithological rock types; and NWTC tunnel (Lot2) has 21 Lithological rock types. The parameters for rock classification, such as rock quality designation (RQD), rock mass ratin...

Effect of Cement on Compressibility and Microstructure of Tropical Peat

Peats are geotechnically problematic soil due to their high compressibility and low shear strength. Cement is widely used for the stabilization of peat by deep mixing method (DMM). This paper presents the results of the model study of compressibility property of peats stabilized with cement columns formed by DMM. The results of consolidation test, scanning electron micrographs (SEM) and energy dispersive x-ray spectrometer (EDX) showed that the compressibility of peats can be improved significantly by the installation of cement stabilized columns. The amount of cement used to form the column was observed to influence the engineering behaviour of treated tropical peats and it had more influence on sapric peat than on hemic and fibrous peats.

SQUEEZING POTENTIAL EVALUATION OF TUNNEL IN TROPICAL AREA

In recent years, there has been an increasing interest in the tunnel construction. This part describes the squeezing behavior of poor rock mass associated with deformability and strength properties. Squeezing phenomena happen in tunnels which are surrounded by weak and moderately strength of rock. Squeezing cause to deformed the tunnels cross section and wastes a lot of human and natural source in all of the word every year. The purpose of current study is to determine methods employed to classifying and quantifying of potential squeezing in tunnel. The results show that some part of case-study tunnel has potential of squeezing. Along with the empirical and semi-empirical approaches is available in order to evaluating of potential of squeezing in tunnel are presented moreover squeezing potential evaluation of Padang Renas tunnel which is located in tropical area (Malaysia) are presented. . The implications of the anticipated ground conditions and squeezing on machine and ground support selection as well as the field observation of the actual conditions are discussed in this paper.

Risk management overview of tunnels using numerical modeling

Purpose – The purpose of this paper is to introduce the numerical methods in tunnel engineering and their capabilities to indicate the fracture and failure in all kinds of tunneling methods such as New Austrian Tunneling Method, tunnel boring machine and cut‐cover. An essential definition of numerical modeling of tunnels to determine the interaction between geo‐material (soil and rock) surrounding the tunnel structure is discussed.Design/methodology/approach – Tunnel geo‐material (soil and rock) interaction requires advanced constitutive models for the numerical simulation of linear, nonlinear, time‐dependent, anisotropic, isotropic, homogenous and nonhomogeneous behaviors. The numerical models discussed in this paper are developed in finite element method (FEM), finite deference method (FDM), boundary element method and discrete element method and these tools are used to illustrate the behavior of tunnel structure deformation under different loads and in complicated conditions. The disadvantage of this m...