Long-term stability of mountain tunnels is disrupted by natural causes such as ground pressure and earthquakes. In some cases, their serviceability is disturbed by deterioration of lining concrete. There are 280.5 kilometers of tunnels in Sanyo Shinkansen. Among them, 16.8 kilometers are reinforced concrete structures. Rock pockets and cold joints are main causes of loose parts of lining concrete. They are mainly defects at the time of construction, and once they are removed, further deterioration is limited. However, the cause of loose parts of reinforced lining is carbonation combined with deficiency in the depth of cover of rebars, and carbonation continues into the future. In order to ensure long-term performance of tunnels with reinforced lining, the authors have developed a new technology of inner lining. Members of the new lining were tested in laboratory, and confirmed they will withstand grouting pressure, wind pressure caused by train operation, and weight of loose parts of concrete. Mock tunnel was constructed and test executions were carried out to verify execution time before actual construction.

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This paper reports on the development of an advanced slope disaster monitoring system for practical use. In 2010, we developed a distributed wireless sensor network and installed it on a slope along an expressway to detect and monitor water behavior and deformations in the slope due to heavy rainfalls at an early stage. In this previous research, three major issues remained unresolved: poor wireless communication data collection rate, sensing performance, and monitoring system. To resolve these issues, in 2013, improved monitoring systems with wireless mesh network functions were set up on slopes along six expressways managed by the West Nippon Expressway Company in Japan. Consequently, we confirmed that data were constantly being sent to the data server every ten minutes, even at single-hop wireless communication distances up to 400 m. Improvements in the sensor nodes by adding strain gauge sensors and contact input and output devices made them useful not only for monitoring slope failure but also for maintenance of the slope by the ground anchor method and evaluation of the drainage effect of the embankment. (However, improvements in the electric field strength and addition of a retry function resulted in a decline in battery life.) The improved monitoring system allows road managers to view the data at each site at any time. Further, the data can also be downloaded from the webserver on the Internet.

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This paper presents forensic investigations of earthquake induced failures during Sikkim 2011 Earthquake, India. Detailed field geotechnical observations and geophysical investigations have been carried out at selected locations affected by 2011 Sikkim earthquake. Field observation, drilling of boreholes with sample collection (DBS), surface wave testing by Multichannel Analysis of Surface Wave (MASW) method and Ground Penetrating Radar (GPR) survey have been carried out at sites having slope failures, settlement and structural failures. Three different failure cases: distressed pavement over a natural slope, a school building, and secretariat building failures are discussed with reference to the field tests carried out. GPR radargram showed the cracked portion of pavement and the depth of the cracks. DBS and MASW at school building show the presence of loose cohesionless soil layer below the top dense layer, which might have undergone cyclic mobility and hence resulted in a settlement and cracks in the floor slab. GPR investigation at Sikkim secretariat building showed that the building is constructed on a sloped ground, where one side is filled with soil (damaged side) and the other side is directly resting on the rock. The study highlights the possible reasons for local seismic wave amplification and the associated damage with the help of field investigation carried out.

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Geotechnical investigation involving failed structures can vary from open surface failures of roadside slopes to underground tunnel collapses. Remote sensing techniques naturally adapts to geo-problem investigation. This paper discusses innovative remote sensing technologies that are being developed for geotechnical investigations. Remote sensing refers to non-contact sensing from a distance away. Most remote sensing techniques such as satellite imaging and aerial LiDAR scans have been popular for geo-spatial analysis. More recently, close range remote sensing techniques have been developed into terrestrial or near-ground technologies. In this paper, focus is placed on remote sensing techniques that do not require surface treatments and techniques that can be used for quantitative measurements. Four techniques are described herein: terrestrial LiDAR scan, rapid shooting camera (RSCS) system, small format aerial photography (SFAP) and unmanned aerial vehicle (UAV) imaging.

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Three different problems are also described in the current paper i.e. the effect of faulting on buried pipes, segmental tunnels as well as shallow foundations. Effect of embedment depth as well as pipe type are investigated in the first study. In the second set of tests the performance of shallow foundations with different embedment depths and different contact pressures were studied. In the third study the behavior of segmental tunnels against faulting were the main subject. Interesting behavior of these tunnels are described and all failure mechanisms are introduced.

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The stratums along the Beijing-Shanghai high-speed railway are composed mainly with soft soil. The foundation of roadbed were strengthened in hope of reducing differential and total settlement. Ram-compacted piles are mentioned in this paper, as an example of strengthening methods. Using joint test method combining liquid level settlement gauges and single point settlement gauges, total settlements and compressions at different depths were measured. Field test results showed that:1. The settlements were significantly reduced. 2. The settlement of the basement with cap at the middle of roadbed mainly appeared during filling stage, and that without cap indicated a 30-day-stablisation during preloading stage. 3. The up thorn can be decreased by pile cap. 4. The largest settlement was found at roadbed center, whereas the smallest occurred at embankment toe. Ram-compacted piles successfully reduced settlement of roadbed, offering reference value to high-speed railway design.

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