This paper considers techniques for inferring the cause of deformation in the lining of tunnels by the extracted normal type of cracks using a Tunnel-Lining Crack Index ("TCI") calculated from on internal elevations, of cracks found in the lining of road tunnels administered by East Nippon Expressway Company Limited, Central Nippon Expressway Company Limited and West Nippon Expressway Company Limited (together "NEXCO"). As a result, deformation inferred to be due to internal causes and external causes was able to be classified quantitatively. Further, for tunnels deformed by external forces, the interrelation between the configuration of cracks and deformation of the tunnel cross section was able to be determined by implementing measurement of the tunnel cross section using a Mobile Mapping System.

View full abstract

 The evaluation of the detailed inspection of the tunnel linings of the various Nippon Expressway companies (NEXCO) is carried out, based on the Tunnel-Lining Crack Index (TCI). In order to increase the precision and efficiency of inspections of tunnel linings in expressways, this paper analyses the data from multiple detailed inspections of 9 683 spans in 99 tunnels, in an effort to incorporate the progressive propagation of cracks as an index of quantitative evaluation. As a result of this data analysis, it was found that it is possible to evaluate the progress of propagation quantitatively, using the TCI.

View full abstract

 Preventing concrete spalling is very important in tunnel maintenance because spalling in railway tunnels may causes a direct safety hazard to train operations. This paper compared sprayed polyurea with alamido fiber sheet in bending test, model tunnel loading test. Cold joint was focused on in model tunnel lining test. Trial construction in an actual tunnel in cold region were carried out changing conditions of seepage and surface preparation. Pull-off adhesion testing was carried out and confirmed that adhesive strength of polyurea was sufficient even a winter of cold district has passed. No relationship could be seen among seepage, surface preparation and adhesive strength within the conditions of this trial construction.

View full abstract

 It is highly possible that the concrete lining at the tunnel entrance will suffer from thermal cracks and drying shrinkage due to its exposure to external air and the scattering of snow melting agent. In this sense, in order to avoid thermal cracks, “localized pipe cooling” and “expansive concrete” were implemented. On the other hand, as an attempt to avoid drying shrinkage cracks and salt-attacks, the “water supply curing system with sheet suction” was implemented on the actual construction site. The effects of these measures on improving quality were quantitatively recorded on site and a three-dimensional FEM thermal stress analysis was modelled. The adoption of these countermeasures reduced the probability of occurrence of thermal cracks by about 30%, the drying shrinkage on the surface was reduced by 50～130×10^-6 and the coefficient of permeability to air was improved by a factor of 1/15～1/4. Further, the effect of expansive concrete utilizing a conventional technology was compared, confirming that implementing the localized pipe cooling method was more effective.

View full abstract

 Accurate prediction of the geological conditions ahead of the tunnel face is essential for safe and economical tunnel construction. As an application of the drill logging, a new method for predicting the distribution of seismic velocity ahead of the tunnel face has been developed. The method makes it possible to determine the travel time from transmission to reception by determining the transmission time at which the rock is hit by the drill bit and processing the wave form of the vibration received by the receivers on the tunnel face. Field test results have shown that the newly developed method is useful in predicting the seismic wave velocity distribution ahead of the tunnel face.

View full abstract

 The visualization system of soil fluidity in the EPB TBM chamber has been developed. The system visualizes 3 dimensional soil fluidity based on numerical analysis with the assumed soil viscosity measured by flapper torque. This paper introduces technical methods of the visualization system, experimental approach of the clarification of properties of soil viscosity and results of the visualization system installed to actual TBM. It is concluded that the properties of soil viscosity can be measured by the flapper torque in the chamber with its appropriate rotation speed, and soil fluidity can be evaluated with the viscosity and shear stress of soil in the chamber based on flow analysis of the visualization system.

View full abstract

 To design an adequate reinforcement for an aged shield tunnel constructed in soft ground, it is important to predict precisely the future load increase, when the consolidation of the surrounding ground is proceeding with water leakage into the tunnel. However, the specification of the reinforcement could be designed overengineered with the conventional method, because the load increase is calculated with assumption that the maximum water leakage should be happening since the construction of this tunnel. In this paper, a method to predict future load increase appropriately is devised, using the water leakage condition of a tunnel and the change of inner displacement, and the validity of this method is discussed by using the field measurement results.

View full abstract

 The effect of opening width is not properly taken into account with the conventional 2D frame analysis, in which hinges are installed at the top and bottom of a virtual beam with decreased stiffness at the opening part. This research proposes a 2D frame analysis method, which can take into account the effect of opening width by installing the rotation spring with torsional stiffness according to the opening width and shape of remaining haunch. This paper investigates the influence of opening at side wall on the members of existing cut-and-cover tunnels by means of 3D FEM. The proposed 2D frame analysis method is also verified by comparing the results with those of 3D FEM and enables to judge the necessity of reinforcement.

View full abstract