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List of products by author: N. Isago
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An Evaluation on Load-Bearing Capacity of Rock Tunnel Lining against Earthquake-attributed Loading
Abstract: Huge earthquakes can pose serious risks even for rock tunnels, as evidenced by large earthquakes in the past. In a large earthquake in Japan in 2004, some tunnels suffered severe damages including collapse of their permanent lining, even though the tunnels were constructed in ordinary ground conditions. To mitigate such risks, mechanical behavior of tunnel lining during earthquake should be...
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Behavior of lining concrete under high temperature condition
Abstract: Permanent lining has various functions for tunnel and naturally the fire proof resistance is included, and it is expected to confirm the safety for users. The road tunnels in Japan constructed by conventional method uses plain concrete as permanent lining in general conditions. The thickness is 30 cm and its compressive strength is 18 MPa mainly [1]. Installation of emergency facilities against...
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Countermeasure for deformed road tunnel by precast concrete members with partial thin thickness
Abstract: There are more than 10,000 road tunnels in Japan, and every year, more and more tunnels reach the end of their service lifetimes. These tunnels include some in which their lining concrete has been deformed by external force so that they require reinforcement measures. The authors have developed a reinforcement method that can guarantee adequate load-bearing capacity by using precast concrete...
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Deformation mechanism and effect of countermeasure for tunnel under swelling rock condition
Abstract: Temporary support of tunnel is generally constructed conforming to ground condition on the result of observation and measurement during construction, and permanent lining is constructed after the judgment of convergence of displacement. Deformation and defect during service stage is grasped by periodical inspection, and some countermeasures are performed if necessary. Then, cracks over lining...
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Displacement Control Effect of the Ground in front of the Main Tunnel Face with the Drift Using High Rigidity...
Abstract: The fragile Nichinan Group is distributed in southern Miyazaki Prefecture, Japan. The Higashi Kyushu Expressway Yoshinomoto Tunnel is a two-lane tunnel with a length of 1,880m, which is planned in this fragile Nichinan Group. The authors applied Center Drift Advancing method using the drift with high rigidity support to the Yoshinomoto tunnel. As a result based on the measurement at the time of...
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Influence of stiffness of back-fill grouting material for void above tunnel lining upon load-bearing capacity of...
Abstract: Void above a tunnel lining is harmful to a tunnel structure in some cases especially in poor ground conditions. The void often exists in old tunnels constructed with the steel rib and lagging method, and back-fill grouting is one of the most effective countermeasures against the void. Stiffness of the back-fill grouting material is an important factor and should be examined appropriately to...
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Large deformation mechanism of lining through actual data and model experiment
Abstract: Tunnel structure may be largely deformed or collapsed by larger force than expected in design. Big earthquake occurred in Japan and the collapse of permanent lining and the destruction of temporary lining such as fracture of steel arched support in road tunnels have been reported several times for over 20 years. Some mountain tunnels also encountered extreme squeezing and swelling geological...
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Long-term durability of permanent lining concrete in mountain tunnel
Abstract: Up-close visual inspections have been mandatory and hammering tests were done as necessary in periodical inspections for all road tunnels in Japan from 2014. Information obtained by the inspections should be accurately evaluated in order to diagnose soundness of the tunnels and take proper countermeasures correctly. Defect and deformation mechanisms of the permanent lining of mountain...
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Mechanical Behavior of Mountain Tunnel during Earthquake Based on Dynamic Measurement in an Actual Tunnel
Abstract: Rock tunnels suffered severe damage from recent large earthquakes in Japan, despite the empirical knowledge that tunnels tolerate earthquakes better than surface structures. Seismic design for rock tunnels have therefore become a fascinating subject for many tunnel engineers. However, even basic behavior of tunnel has not been fully understood due to lack of actual seismic data. In this study,...
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Performance of rock bolt with differe nt material by on-site and model experiments
Abstract: Although the tensile and shear resistance performances of rock bolts have been extensively studied, other performance measures such as compression and erosion resistance are required to be examined. Various types of rock bolts have been developed recently; however, owing to the lack of experience in tunneling and data on the use of support members in design and construction, it is difficult to...
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Waterproof Rock Tunnels for the Preservation of Hydrological Environment
Abstract: Waterproof rock tunnels have been constructed in Japan when it was necessary to reduce the impact on the hydrological environment. This study performed case analyses of existing waterproof rock tunnels in Japan and seepage analysis on the hydrological behaviour related to the waterproof rock tunnels to discuss the practicability of design and construction. The results of the case analyses show...
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