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Objective APM (automated people mover) has very high requirements for safety, and the existing SIL (safety integrity level) allocation method cannot meet the demand of APM projects efficiently and accurately. In order to ensure the safety and reliability of APM, further in-depth research should be conducted on the allocation of SIL and the determination of the safety targets for APM. Method The existing methods for SIL allocation in APM are elaborated, and a widely recognized method MODSafe (modular urban transport safety and security analysis) is proposed and applied for SIL allocation of APM. The basic steps of the MODSafe method are introduced, and the respective SIL allocation steps are clarified under the two modes of high and low safety demands. The technical idea for conducting SIL allocation based on MODSafe method is further elaborated with the train jerk control function of APM as the example. Result & Conclusion Identifying safety functions and determining safety targets in the initial design phase is crucial for the safe delivery， operation and other aspects of APM projects. The MODSafe method can be used to quantitatively determine the THR (tolerable hazard rate) and SIL of APM safety functions.

The presence of karst formations significantly impacts the load-bearing capacity of pile foundations in karst geological environments, posing a challenge to their design. This study investigated the bearing characteristics of karst pile foundations using the physical model test and numerical analysis. First, the influence of cave height and span on the bearing capacity of pile foundations is examined using model tests. The results demonstrate that the height of karst caves greatly affects the bearing capacity of karst pile foundations. Subsequently, numerical analysis further explores the bearing characteristics of these foundations. It reveals that as the top load on pile increases, an arch-shaped tensile damage zone forms at the top of karst cave and gradually expands. The rock failure in this area leads to a decrease in adhesion between rock strata and pile foundation, consequently reducing its load-bearing capacity. Finally, experimental results are compared with numerical results to validate consistency and mutual verifiability between physical model tests and numerical analyses. The outcomes of the research provide valuable insights for designing rock-socketed pile foundations in similar karst areas.

This paper presents an extensive laboratory investigation of layered salt rocks under triaxial loading and unloading cycles aiming to better understand their viscoelastic plasticity strain characteristics. Specifically, creep curves were obtained from the triaxial loading and unloading tests and analyzed using the Burgers model. The microstructure of the layered salt rocks before and after the creep test was comparatively analyzed using the dry grinding optical diagram. The results show that the creep deformation of layered salt rocks is mainly viscoelastic under a low deviatoric stress and contains both viscoelastic and viscoplastic deformations when the deviatoric stress is high. With the increase of deviatoric stress, both the instantaneous elastic and plastic strains increase, and the increasing rate becomes lower as the deviatoric stress increases. The creep curves of layered salt rocks can be well represented with the Burgers model. Since the creep leads to fracturing and interlayer rupturing and producing new fluid seepage channels in layered salt rocks, this study has great value for understanding the long-term performance of gas and hydrocarbon liquid storage caverns in layered salt rock formation.

To better study the shear characteristics of infilled joints with soil having different moisture contents, the influence of the moisture content on the shear characteristics of the infilled joint was explored in this paper, and a revised shear strength model of infilled joint surface is proposed. The results show that the shear dilatation modes of joints can be divided into four types: pure shear dilatation, pure shear compression, shear dilation-shear compression and shear compression-shear dilation. As the joint roughness coefficient (JRC) value increases, the normal displacement of the joint surface gradually increases during the shearing process and the normal stress has an inhibitory effect on dilatation. The infill material will weaken the peak shear stress of the joint surface. When the JRC value of joint surface is small, the weakening effect of soil with moisture content of 30% on peak shear stress is obvious. The revised joint roughness coefficient-joint wall compressive strength (JRC-JCS) model of infilled joint is proposed and the maximum shear stress value calculated by the model has a good linear relationship with the test value.