InSAR Constrained Downdip and Updip Afterslip Following the 2015 Nepal Earthquake: New Insights into Moment Budget of the Main Himalayan Thrust

We use ALOS-2 and Sentinel-1 data spanning 2015-2020 to obtain the post-seismic deformation of the 2015 Mw 7.8 Nepal earthquake. ALOS-2 observations reveal that the post-seismic deformation was mainly distributed in four areas. A large-scale uplift deformation occurred in the northern subsidence area of the co-seismic deformation field, with a maximum uplift of ~80mm within 4.5 yr after the mainshock. While in the southern coseismic uplift area, the direction of the post-seismic deformation is generally opposite to the co-seismic deformation. Additionally, two notable deformation areas are located in the region around 29°N, and near the MFT, respectively. Sentinel-1 observations reveal post-seismic uplift deformation on the north side of the co-seismic deformation field with an average rate of ~20 mm/yr in line-of-stght. The kinematic afterslip constrained by InSAR data shows that the frictional slip is distributed in both updip and downdip areas. The maximum cumulative afterslip is 0.35 m in downdip areas, and 0.2 m in the updip areas, constrained by the ALOS measurements. The stress-driven afterslip model shows that the afterslip is distributed in the downdip area with a maximum slip of 0.3m during the first year after the earthquake. Within the 4.5 years after the mainshock, the estimated moment released by afterslip is ~1.5174 × 1020 Nm,about 21.2% of that released by the main earthquake.

Deformations of Subway Tunnels Induced by the Overcrossing Jacked Box Tunnels

The rectangular utility tunnels have been increasingly built in urban areas in recent decades. In this paper, a case of jacked box tunnels built closely over-crossing the existing subway tunnels in Suzhou, China, is presented. The tunneling-induced deformation of the subway tunnels is measured and analyzed. The measurement indicates that the subway tunnels are uplifted and subjected to the overcrossing box tunneling. As compared, the longitudinal deformation of the range that locates under the box tunnels is more significant than that outside the range. The tunneling-induced deformation of the left subway tunnel is relatively higher than that of the right one. The numerical simulation is performed for validation. The numerical result is agreed with the in-situ measurements. Moreover, the simulation reveals that the presence of friction in jacked tunnels causes the extra uplift deformation of subway tunnels. The higher the friction, the is the deformation. It is affirmed that using the effective lubrication not only facilitates the tunnel jacking but also inabilities the tunneling-induced deformation of underlying tunnels.

Uplift Deformation of the Bottom Plate of the Cylindrical Shell Tanks Under Steady-State Response of Tank Rocking Motion

The uplift phenomenon of a flat-bottom cylindrical shell tank is a long-term unsolved problem. In this study, uplift deformation of a tank bottom plate calculated by an explicit finite element analysis (refer to PVP2016-63916) is observed, and a hand calculating model based on Euler–Bernoulli beam theory is examined by comparing with the results of the numerical analysis. First, this study analyzes the results of uplift displacement and uplift width calculated by the FE analysis. Then, the results of the relationship between the uplift displacement and the uplift width are observed. Moreover, comparing the results of the maximum uplift width of a thick bottom plate case and a thin bottom plate case, trends of the maximum uplift width that depends on the thickness of the tank bottom plate are obtained. Seconds, this study tries to verify the hand calculating model based on Euler–Bernoulli beam theory. Compering the results of the deformation of the tank bottom plate calculated by the hand calculation and the FE analysis, accuracy of the hand calculating model is examined. The comparison implies that the hand calculating model may be able to estimate uplift deformation of the tank bottom plate until the uplift displacement of the juncture reaches some height even though the geometrical nonlinearity is not considered.

Numerical Simulation of Effect of Foundation Pit Excavation on Underlain Shield Tunnel

In the background of a foundation pit excavation project on Yanan Road in Hangzhou City, this study simulated the excavation of foundation pit above an underground tunnel using 3D MIDAS/GTS software. The combined action of foundation pit, ground and tunnel were considered. The influence of foundation pit excavation on the deformation of underlain shield tunnel was evaluated and simulations were carried out on the effectiveness of different strengthening and control approaches. Results from the research showed that during the stages of piling and ground strengthening, settlement occurred at the tunnel; with the excavation of foundation pit, uplift deformation at the bottom of the foundation pit and the tunnel increased; with stricter strengthening and control techniques employed, the magnitude of uplift at the tunnel and bottom of the foundation pit reduced, suggesting that various control procedures were effective to some extent.