Theoretical investigation of interaction between a rectangular plate and fractional viscoelastic foundation

The interaction between plates and foundations is a typical problem encountered in geotechnical engineering. The long-term plate performance is highly dependent on the theological characteristics of ground soil. Compared with conventional linear theology, the fractional calculus-based theory is a more powerful mathematical tool that can address this issue. This paper proposes a fractional Merchant model （FMM） to investigate the time-dependent behavior of a simply supported rectangular plate on viscoelastic foundation. The correspondence principle involving Laplace transforms was employed to derive the closed-form solutions of plate response under uniformly distributed load. The plate deflection, bending moment, and foundation reaction calculated using the FMM were compared with the results obtained from the analogous elastic model （EM） and the standard Merchant model （SMM）. It is shown that the upper and lower bound solutions of the FMM can be determined using the EM. In addition, a parametric study was performed to examine the influences of the model parameters on the time- dependent behavior of the plate-foundation interaction problem. The results indicate that a small fractional differential order corresponds to a plate resting on a sandy soil foundation, while the fractional differential order value should be increased for a clayey soil foundation. The long-term performance of a foundation plate can be accurately simulated by varying the values of the fractional differential order and the viscosity coefficient. The observations from this study reveal that the proposed fractional model has the capability to capture the variation of plate deflection over many decades of time.

Study on Ground Deformation during Shield Tunnel Construction

Through the systematic analysis of the ground settlement generated by the process of shield tunneling,the relationships between ground deformation and construction parameters are studied in this paper.Based on the assumption of linear small deformation,a mathematical model of the relationship between ground deformation and construction parameters is set up.The principle and method of optimization for estimating ground deformation is studied.The actual measured data are compared with the results of theoretical analysis in a case.Considering different ground formations in different construction sites with different adverse effects on surface and underground structures,the ground surface deformations caused by shield tunneling is an aimed topic in this paper.The contributions and research implications are the revealed relationships between the ground deformation and the shield tunneling parameters during construction.

Comparison of settlement behaviors of high-food-waste-content(HFWC) and low-food-waste-content(LFWC) MSWs and assessment of their prediction models

Settlement behaviors of high-food-waste-content(HFWC) and low-food-waste-content(LFWC) municipal solid wastes(MSWs) respectively from developing and developed countries were characterized and compared based on a great number of experimental datasets from references. Fresh HFWC-MSW generally has larger primary compression ratio compared to fresh LFWC-MSW, due to the release of a large amount of intra-particle water contained in food waste under additional stresses. The slopes of strain-logarithmic time curves with respect to the three secondary compression phases are characterized as "slightsteep-slight" for LFWC-MSWand "moderate-moderate-slight" for HFWC-MSW. It is difficult to distinguish the first two phases of the secondary compression in strain-logarithmic time curves for HFWC-MSW. The entropy method was built to evaluate the performance and applicability of nine published settlement models based on the settlement datasets of four large-scale experiments. The computational simplicity, the fitting performance, the prediction performance and the parametric stability were taken as the four criterions in the entropy method. Based on the evaluation results, the models proposed by Sowers et al.(1973)and Gourc et al.(2010) are recommended for predicting settlement at LFWC-MSW landfills, while the hyperbolic model and the Chen et al.(2010) model are recommended for HFWC-MSW landfills.