Research on 3d elastoplastic numerical analysis of settlement joint of shield tunnel based on the interaction between soil and structure
Considering the effect on uneven settlement of tunnel longitudinal stratum, a 3d elastoplastic numerical model is established for the arrangement of settlement joint and the calculation of force and deformation of tunnel longitudinal structure based on the interaction between soil and structure. In the FEM calculation model, soil material is elastoplastic, the soil constitutive model selected Mohr Coulomb, the element type of soil choose a three-dimensional solid element, the element type of segment structure use space shell element, and settlement joint use three-dimensional linear elastic spring. Calculation shows that, this calculation model is able to fully consider the impact of tunnel the uneven settlement of all factors, and may better simulate the vertical force and deformation behavior of tunnel structure in complex ground formation conditions. Research conclusion gives the vertical force and deformation of the tunnel structure under the condition of different set of settlement joint, and has an important reference value for the future design and construction of the tunnel lining structure.
Numerical Study on the Effect of Grouting on Long-Term Settlement of Tunnels in Clay
The long-term settlements over tunnels can be rather significant, particularly when tunnels are embedded in soft and compressible soils. The influence of grouting on the evolution of long-term surface settlement, as well as ground loss, is simulated by imposing prescribed volumetric strain on the disturbed area around the tunnel due to shield tunneling. The volumetric strain could be detected from the grouting ratio of grouting volume and the volume of the physical gap of shield tunnel. Finally, some conclusions are drawn from the numerical simulations.
Archaeological Survey of Dangoyama Kofun by 3DGPR
We presented a three-dimensional ground penetrating radar (3DGPR) system for the archeological investigation in a harsh site, where we have to deal with many trees and/or great topographic variations. This system consists of a commercial GPR system with a laser positioning system. With this system, we can move the GPR antenna freely, on which a positioning detector can record accurate position for each GPR data trace. We applied our 3DGPR system at Dangoyama Kofun, a burial mound, in Fukushima prefecture, Japan. A lot of trees and bushes covered the survey area and cannot be cut. We acquired six datasets in two days in this area. We successfully imaged the boundary between the original surface of the burial mound and the covering soil clearly at about 0.3 m depth around the mound. Furthermore, we found some strong reflections appeared at 0.8 m depth in the top area of the mound, which can be from the artificial parts of the burial mound. The results would greatly aid the following archaeological excavation. In addition, we compared the non-interpolated depth slice with interpolated depth slice at same position and demonstrated that the interpolation process on threedimensional GPR data may introduce some artifacts which might mislead our interpretation.