A Novel Experimental Study on the Effects of Soil and Faults’ Properties on Tunnels Induced by Normal and Reverse Faults

Abstract

Due to the world population increasing considerably, there is a need for efficient public transportation, such as the subway. However, it has become a major concern to geotechnical engineers that the development and construction of subways are held underground where faults exist, as it will be a major risk to any structure if the fault is still active. Several seismic events, such as the earthquakes in Taiwan in 1999, China in 2008, and Malaysia (Sabah) in 2015, caused by fault ruptures, signify the importance of this study. In this paper, a physical model of 1000 mm in height, 3000 mm in length, and 1000 mm in width, which is the largest single gravity (1g) model for simulation faults (normal and reverse) ever built, was fabricated to evaluate the influence of various soil properties, various fault angles, and tunnel depths on tunnels affected by normal and reverse faults. The effects of various soil properties, such as water content, particle size, cohesion, and friction angle, had revealed major changes (approximately by 34%, 39%, 64%, and 39%, respectively) in tunnel displacements. Results also showed that increasing of fault angle could increase the tunnel displacement as much as two times. In addition, when a tunnel is located close to the ground surface, 22% less displacement was found to have occurred to the tunnel. With the results obtained from the physical model, simulation had been made using plane strain and axial symmetry (PLAXIS) software. The comparison made between rock and soft soil showed that soft soil imposed two times more displacements than rock, and an existence of foundation in soft soil and rock can decrease the tunnel displacements by 6% and 4%, respectively. This paper asserts that besides the structural design of a tunnel, the geotechnical design also has a major impact on the safety and robustness of the tunnel, in which aspects such as soil properties, tunnel depth, and fault angle have a strong influence on tunnel damages which were not considered in previous research, despite their importance.

Analysis of Bridge Tests on Sandy Overburden Site with Fault Dislocating

“…Accelerometers were strategically placed on both sides of the pile body, bearing platform, and bridge deck of the bridge structure, as illustrated in Figure 6. In Test 3 ⃝, the rightmost side of the bridge bearing platform was 700 mm away from the soil box plate on the east side, and in Test 4 ⃝, the distance to the east side of the soil box plate was 1100 mm.…”

“…During a strong earthquake, the displacement of bedrock can rupture the overlying soil layer, causing the destruction of buildings and rendering bridge structures nonfunctional. This phenomenon is referred to as the surface rupture effect in strong earthquakes [1][2][3][4]. The surface rupture resulting from the primary fault during a strong earthquake is highly destructive, and current seismic fortification measures struggle to mitigate the direct damage caused to buildings and critical lifeline infrastructure [5].…”

Spatial Modelling in Environmental Analysis and Civil Engineering

“…An important subject, described in the special issue was the development of manmade infrastructure in relation to the processes of the natural environment taking place in the vicinity of this infrastructure. Ghafari et al [2] shows the problem related to the development of transport. Its expansion is very important due to the constantly growing number of people using it.…”

Analysis of Extent of Deformation Range and Failure Characteristics of Rocks Surrounding a Tunnel Crossing Fault Zone Based on FDEM

“…Extensive research has been carried out on fault-crossing tunnels, including analysis models, experiments, and numerical simulation. Key influencing factors of fault zones studied have included the fault zone width, soil properties, and the intersection angle between tunnel axis and fault zone [7,8]. Tunnelling research subjects have encompassed surrounding rock deformation, internal forces, tunnel lining deformation, and the advantages and drawbacks of a range of construction measures [9][10][11][12][13].…”