Research on the design of ballastless track in the subgrade section of highspeed railway in high earthquake-intensity area

According to the characteristics of complex terrain and bad geological conditions in the southwest mountainous area of China, it is proposed that cast-in situ double-block ballastless track with layers and blocks structure should be adopted preferentially in the subgrade section of high-speed railway, which is conducive to the construction, prolongation of service life and maintenance of the ballastless track. Based on the finite element model, the dynamic performance, structural strength and stability of double-block ballastless track under high earthquake-intensity action are analyzed. The analysis shows that the relative displacement between the base slab of ballastless track and the subgrade may occur under 9 degree earthquake action. A new CRTS double-block ballastless track structure with a concave-convex structure between the base slab and the subgrade is proposed in the subgrade section, and its additional stress and relative displacement under earthquake are analyzed. The results show that the additional stress and relative displacement of the new ballastless track structure and the subgrade under 9-degree earthquake actions are small, which meet the high stability requirements of high-speed railway.

Research on Instability Mechanism and Type of Ore Pillar Based on the Fold Catastrophe Theory

The stability of ore pillar in mine is essential for the safe and efficient mining.Based on the energy evolvement rule in ore pillar and roadway roof system,the roadway roof and ore pillar are treated as energy release body and energy dissipation body,respectively.Therefore,the double-block mechanical model is established with energy dissipation body and energy release body,and the energy mechanism of ore pillar instability is obtained,based on the fold catastrophe mathematical theory.The research result indicates that the dynamic instability of ore pillar is a physical instability problem caused by the strain softening property of ore mass,and the instability type of ore pillar is determined by the stiffness parameter of double-block mechanical system.When the systematical stiffness parameter is greater than or equal to 1,the equilibrium position of double-block mechanical system passes through shaft K-1 or the origin,from branch 1 of unstable equilibrium state to branch 2 of stable equilibrium state by smooth transition,and the ore pillar shows quasi-static fracture.When the systematical stiffness parameter is less than 1,the equilibrium position of double-block system mutates from branch 1 of unstable equilibrium state to branch 2 of stable equilibrium state by jumping transition,and the ore pillar shows dynamic instability.The research result could provide theoretical guidance for the prevention measures of ore pillar instability.

Cross-fault Newton force measurement for Earthquake prediction

Earthquake prediction is a common scientific challenge for academics worldwide.This dilemma originates from the lack of precursory indicators that meet the sufficient and necessary conditions of earthquake occurrence,which may be the root cause of the failure of earthquake prediction.In light of this,a double-block catastrophic mechanics theory for earthquakes based on cross-fault Newton force measurement is proposed herein.Based on this theory and laboratory physical model tests of seismic Newton force monitoring,a new academic thought is envisioned“the sufficient and necessary condition for earthquake occurrence is the change of Newton force,and the sudden drop of Newton force on the fault surface can be used as a predictor of earthquake disaster.”Several equipment systems have been independently developed,and the technology has been successfully applied to engineering practice.This concept has currently been proven in small-scale double-block catastrophic events such as landslides.Based on the double-block catastrophic mechanics theory,landslides and earthquakes have the similar nature but different scales.According to the on-site monitoring of landslides,it is verified that the sudden drop of Newton force can be used as a predictor of landslide disaster which successfully solves the problem of short-term landslide prediction.The introduction of cross-fault Newton force measurement technology and idea has laid a foundation for improving the method and level of international earthquake monitoring and solving the world-class scientific problem of short-term earthquake prediction.