Stability Analysis and Support Design of Imam Reza Tunnel in Ardabil Sarcham Road by Numerical Methods (original) (raw)
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Scientific Research and Essays, 2011
In this paper, a detailed geomechanical investigation of rock masses of North Water Convey Tunnel (NWCT) and its stability analysis has been carried out. The NWCT is located in the north of Iran and is to be constructed in-order to convey water for agriculture purposes. The main instability in the tunnel is joints and faults. The rocks mass encountered in the tunnel route are made of argillaceous, sandstone and shale. The tunnel has been divided into two parts, lot1 and lot2 having a length of 14 km and 26 km respectively. It is proposed to be constructed by telescopic shield method using a tunnel boring machine (TBM). In this study, the most suitable methods are utilized for the stability analysis and design of support of the tunnel. For the empirical investigation, the rock mass were classified based on RMR, Q, RSR, GSI and Rmi systems. The geomechanical properties of the rock mass were determined from the laboratory and field investigations. The results obtained from the analysis show that the tunnel is highly unstable due to the presence of a fault and hence strong supports are need in these regions. The support system used is concrete lining, as the tunnel in used for water conveyance. The tunnel alignment in lot1 is divided into 12 lithology types as; LI-SH1, LI-SH2, LI-SH3, LI-SH4, LI1, LI2, LI3, LI4, LI5, SI, CZ and FZ regions. Similarly, the tunnel alignment in lot2 is divided into 21 lithology types as; SH-ML1, SH-ML2, SH-ML3, MLI-SH1, ML-SH2, ML-SH3, ML-SH4, ML-SH5, SH-LS1, SH-LS2, SH-LS3, SH-LS4, LI2, LI3, LI4, LI5, LI6, LI-MA, LI-SH, CZ, FZ regions. A stability analysis is a necessity as during the tunneling instabilities, such as the presence of a shear zones, may cause an obstruction and delaying of TBM progressing rate. Key words: Tunnel boring, stability analysis, rock mass classification system, empirical and numerical methods, support pressure. w r n a J J RQD Q J J SRF = × × (1) This classification system includes six parameters of rock quality as following: 1. Rock quality designation (RQD) 2. The number of joint sets ( n J ) 3. The joint surface roughness ( r J ) 4. The degree of joint weathering and alteration ( a J ) 5. Joint water reduction factor ( w J )
Studia Geotechnica et Mechanica, 2016
The paper analyses the geological conditions of study area, rock mass strength parameters with suitable support structure propositions for the under construction Nahakki tunnel in Mohmand Agency. Geology of study area varies from mica schist to graphitic marble/phyllite to schist. The tunnel ground is classified and divided by the empisical classification systems like Rock mass rating (RMR), Q system (Q), and Geological strength index (GSI). Tunnel support measures are selected based on RMR and Q classification systems. Computer based finite element analysis (FEM) has given yet another dimension to design approach. FEM software Phase2 version 7.017 is used to calculate and compare deformations and stress concentrations around the tunnel, analyze interaction of support systems with excavated rock masses and verify and check the validity of empirically determined excavation and support systems.
Geotechnical and geological studies of NWCT tunnel in Iran focusing on the stabilization analysis an
2011
In this paper, a detailed geomechanical investigation of rock masses of North Water Convey Tunnel (NWCT) and its stability analysis has been carried out. The NWCT is located in the north of Iran and is to be constructed in-order to convey water for agriculture purposes. The main instability in the tunnel is joints and faults. The rocks mass encountered in the tunnel route are made of argillaceous, sandstone and shale. The tunnel has been divided into two parts, lot1 and lot2 having a length of 14 km and 26 km respectively. It is proposed to be constructed by telescopic shield method using a tunnel boring machine (TBM). In this study, the most suitable methods are utilized for the stability analysis and design of support of the tunnel. For the empirical investigation, the rock mass were classified based on RMR, Q, RSR, GSI and Rmi systems. The geomechanical properties of the rock mass were determined from the laboratory and field investigations. The results obtained from the analysis...
Effects of weak rock geomechanical properties on tunnel stability
2012
Numerous tunnels are constructed in various parts of the world. Various technologies such as the Tunneling Boring Machine (TBM), New Austrian Tunneling Method (NATM), cut and cover method, and drilling and blasting method are used in order to aid tunnel constructions. In order to investigate the behavior of tunnels and to enhance these technologies, it is primarily important to investigate the issues pertaining to the soil and rock structure interaction. It is also of prime importance to study their impact on the tunnel system‟s performance. In engineering practice, geotechnical problems such as settlement and ground stability are not given due consideration in tunnel crossing constructions on the ground surface in urban areas. In order to deal with the challenges of geotechnology, full scale experiments may be performed. However it may not be feasible to conduct full scale experiments as it may be expensive. The main purpose of this thesis is to evaluate the ground behavior in term...
Assessment of geotechnical properties Of Draa El Mizane highway tunnel (Algeria)
Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu, 2020
Purpose. To show the results of geotechnical studies and design the support system chosen in complex geological conditions especially in fault zones. The Draa El Mizane highway tunnel was a research site. Methodology. The determination of geotechnical properties by different classification systems for the quality of the rock mass such as the Q index, Rock Mass Rating RMR and the Geological Resistance Index GSI. In addition, the choice of the support system is validated by numerical modeling via the 2D Phase 2 program. Findings. The geotechnical measures developed through extensometer monitoring show a major compatibility between the geotechnical design and the digital simulation, which validates the reliability of the selected support system. Originality. A type of support chosen during construction is established, which corresponds to local specific conditions in order to eliminate instabilities. Practical value. The values obtained by numerical modeling can give us a final decision for the support system chosen: values in terms of deformations-in order of 1.5 cm at the top, 7.5 and 13.5 cm for the left and right wings respectively, 9.0 and 18 cm in the lower half left and right, 22.5 cm for the base of the tunnel. Furthermore, the results obtained by the measurements of instru mentation in the dimensioning of the support type are well illustrated through the measurements by an extensometer, which are very compatible with the results of numerical modeling.
Influences of Crushed Fault Zone in the Stability of Zaker-Sorkhedizaj tunnel, NW Iran
2012
This paper presents the results of engineering geological studies of rock masses in the crushed fault zone along a road tunnel in NW Iran. The tunnel is to cross the Western Alborz Mountain Range through 530 m in length with 11.2 m span and 8 m height. Eocene tuffs and andesites crop out in whole of the tunnel route. The final segment of tunnel is composed of porphyry andesites and a strike-slip fault with reverse component has caused the crushed zone with 20-25 m extent and 20 m cover. Empirical and numerical methods were combined for safe tunnel design in the crushed rock masses. The results of the evaluations show that the crushed rock masses is completely instable in the tunnel and need to an especially support system. The performances of the proposed support systems were analyzed by means of numerical analysis. After applying the suggested support system to the crushed rock masses, tunnel deformation and the yielded elements around the tunnel decreased significantly thus it was...
Stability Analysis and Design of Rock Support for Tunnel and cavern of Kathmandu University Geo-lab
Kathmandu University Journal of Science, Engineering and Technology
This study focuses on the design and stability analysis of underground structures in the Lesser Himalayan Region of Nepal. The rock support design for such opening depends upon the rock mass strength. In this study a proposed Kathmandu University Geo-Lab tunnel and cavern, which passes through weak rock mass conditions, was used as a case study. Existing empirical and analytical methods for the stability of the proposed tunnel and cavern are used for the estimation of support pressure and design support. A detailed numerical study was carried out in 2D finite element analysis to design the tunnel in such region. The results of analysis showed that the support pressure and deformation can be predicted very well from the numerical analysis.Kathmandu University Journal of Science, Engineering and TechnologyVol. 13, No. 1, 2017, page: 1-19
The effect of disturbance factor on the stability of tunnels (Case study: Tunnel No.2 of Kurdistan)
Disturbance factor (D) is related to excavation method and cause damage and stress relief in the rock masses. The convergence and plastic zone around tunnels depends on the disturbance factor of rocks.This study has been in the tunnel No.2 of Kurdistan in NW of Iran which is composed of shale rocks. In tunnel modeling, different disturbance factors(0 to 1) areanalyzed using phase2 software and the amount of displacement and extent of plastic zone in around the tunnelis determined. The obtain results show that by increasing of disturbance factor, the displacement and plastic zone around the tunnel has increased and the most increase has occurred in disturbance factors 0.8 to 1. Therefore, for excavation of this tunnel, the blasting method should not be used and instead of it, the mechanical methods must be used.
Numerical Simulation on the Stability of Surrounding Rock of Horizontal Rock Strata in the Tunnel
Horizontal rock strata is a geological condition of rock which is often encountered in the tunnel construction, and it has an important influence on the tunnel construction, it is necessary to analyze and study the stability of horizontal rock strata in tunnel construction to ensure the tunnel construction's safety and efficiency. By taking " Xishan Highway Tunnel " as the research object, and using the numerical simulation method, the numerical model of the tunnel has been established in the Midas/GTS to simulate the tunnel excavation under the horizontal rock strata condition，and the deformation and failure mechanism of surrounding rock and the influence factors of surrounding rock stability after are studied and analyzed. The research focused on the displacement of surrounding rock horizontal and vertical deformation, the results show that the vertical displacement of the surrounding rock is obviously greater than that of other parts during the excavation of the horizontal rock tunnel. According to the calculation results, the optimization measures of horizontal stratum tunnel construction method are put forward, which has important reference value for ensuring the construction safety and construction quality.