In order to clarify the load-bearing capacity of precast tunnel lining, full-scale tunnel model test has been performed. Based on the experimental results, it has been confirmed that entire structure collapse is caused due to bending compression fracture at the tunnel crown under the condition that load acts on the crown. Numerical analysis using fiber model with non-linear behavior has been also performed to simulate the full-scale model test. From the comparison of analytical and experimental results, it can be concluded that the numerical analysis is applicable to the deformation behavior of precast tunnel lining. In addition, load-bearing capacity of precast tunnel lining calculated by the present numerical analysis has been compared with that of cast-in-place tunnel lining under several load conditions.

 Quality evaluation of concrete surface is generally performed by visual inspection, hence the results depend on the knowledge and experiences of the inspector. The foci of this study are to detect bugholes in detail and to quantify the surface quality of tunnel lining concrete. In this study, color filters were used to emphasize the bugholes in the colored image. To examine the effect of the novel image analysis, the experimental study conducted photo-shooting test at a laboratory and two fields of tunnel construction site. The accuracy of image analysis to detect bugholes was improved by using a kind of color filter.

 The objective of this research is to investigate the hydro-mechanical behavior of rock mass around the shaft in the Horonobe Underground Research Laboratory (URL). The long-term monitoring has been carried out by optical sensors installed below 350m depth of the shaft in the Horonobe URL. From the measurement results, AE activity occurred frequently within 1.5 m from the shaft wall. In this area, significant increase in pore pressure was measured several times as advance of the excavation, then decrease to almost 0 MPa after the excavation. Therefore, the area from the wall surface to a depth of 1.5 m was evaluated as EDZ (Excavation damaged zoon). This EDZ was consistent with the in-situ permeability test results and numerical analysis results.

 At a depth of about 40m near the central Tokyo bay, the medium stiff clay with the N-value of 4 to 8 which is represented by the No. 7 formation distributed. In this case, if the segment is designed on the safe side according to the standard specifications for tunnel, the segment thickness may become unreasonably large, because it is necessary to adopt the total stress conditions with full overburden pressure. On the other hand, in the previous field measurement results of earth pressure and water pressure acting on a shield segment in medium stiff clay, it has been reported that the hydrostatic pressure mainly acts on the segment and the vertical effective earth pressure is less than the overburden pressure. Therefore, in this study, the measurement results of earth pressure and water pressure in medium stiff clay have been numerically analysed using two-dimensional rigid-plastic modelling. In addition, we propose a method for calculating vertical effective earth pressure by the rigid-plastic finite element method and generalized simple numerical method based on the principle of virtual work rate.