Large-scale testing of the mortise and tenon joint performance of the tunnel lining of prefabricated frame tunnels

Seismic fragility analysis of in-service shield tunnels considering surface building and joint-bolt corrosion

Fluid-solid-phase multi-field coupling modeling method for hydraulic fracture of saturated brittle porous materials

A simplified analytical solution for steel plate strengthened circular tunnel concrete linings is presented, considering various interface slip modes. The full derivation for the analytical solution is introduced in detail, from which explicit expressions for the stress and displacement fields throughout the system are obtained. The distribution of lining deformation, internal force, and the interaction stress between tunnel lining and steel plate were investigated by considering various tunnel-steel interface scenarios, namely no slip, full slip, and elastic slip. The result demonstrates the importance of having a well-bonded interface to maximize the benefits of the steel plate strengthening approach. The maximum interface shear stress locates at the position with minimum interface normal stress. Subsequently, the influence of interface shear stiffness and steel plate thickness on the composited tunnel lining performance was investigated. It is founded that the improvement of the interface shear stiffness can enhance the overall structural stiffness of the strengthened tunnel lining, which results in increases in the interaction stresses and lining forces simultaneously. With a ratio of the steel thickness to the tunnel lining thickness less than 0.1, greater achievement in both strengthening effectiveness and cost efficiency is obtained.

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An Analytical Solution for Steel Plate Strengthened Circular Tunnels with Various Interface Slip Modes

In this paper, we propose an approach combining optimal softening laws and a phase-field regularized cohesive zone model (PF-CZM) for modeling the fracture and damage properties of quasi-brittle materials accurately. In this method, the optimal softening law is determined by comparing the predicted results with experimental data in the framework of the PF-CZM; three typical softening laws are considered. The PF-CZM with a length scale is used to model crack initiation and propagation without considering the mesh bias. We first investigate the mechanical responses and crack propagations of different concrete beams based on the above approach; the predicted results are compared with the data from conventional methods and experiments. The results indicate that the mechanical properties of concrete beams with the optimal softening law are better than the data reported in the literature. Further validation indicates that once the optimal softening law is determined, it is stable for the same group of materials. Moreover, we demonstrate that the PF-CZM can naturally predict and reproduce the critical notch offset and fracture transition process of three-point bending concrete beams and the fracture features of typical double-notched concrete beams, such as the interaction between two notches objectively, together with the changes of limit load capacity.

/pdf/numerical-modeling-of-quasi-brittle-materials-using-a-phase-3kekj3s6.pdf

Numerical Modeling of Quasi-Brittle Materials Using a Phase-Field Regularized Cohesive Zone Model with Optimal Softening Law

Cracking feature and mechanical behavior of shield tunnel lining simulated by a phase-field modeling method based on spectral decomposition

In this paper, we propose a novel multi-scale correlation network (MSCNet) for homography estimation from coarse to fine. First, we extract multi-scale features through a siamese network to generate global and local correlations from feature maps of different scales. Second, we use a group dilated deconvolution block to capture global mapping by increasing the receptive fields in terms of different levels. Third, we employ the channel and spatial attention mechanism to achieve local refinement for small displacements. Finally, we adopt a knowledge distillation strategy to lightweight our model while maintaining relatively high estimation performance. Experimental results on Microsoft Common Objects in Context (MSCOCO) dataset show that our proposed MSCNet outperforms the state-of-the-art approaches in terms of accuracy and parameter count. 

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Papers

Cracking feature and mechanical behavior of shield tunnel lining simulated by a phase-field modeling method based on spectral decomposition

Cracking feature and mechanical behavior of shield tunnel lining simulated by a phase-field modeling method based on spectral decomposition

Multi-Scale Correlation for Deep Homography Estimation