The combined peak particle velocity (PPV) and frequency safety criterion for blast vibration is widely used in blasting engineering. However, some field investigations are inconsistent with this criterion. On the basis of field investigations, it is found that there are two failure modes of structures subjected to blasting seismic waves, that is, first-excursion failure and cumulative plastic damage failure. Moreover, the nature of structural responses under blast vibrations is a process of energy input, transformation, and dissipation. Therefore, an energy-based dual safety standard is proposed in this work to more comprehensively explain all failure modes of structures under blast vibrations. To this end, structures are simplified into elastic-plastic single degree of freedom (SDOF) systems with bilinear restoring force models, and energy responses of SDOF systems are then determined using theNewmark-βmethod. From the energy responses, the maximum instantaneous input energy and hysteretic energy are selected as the basis of the dual safety criterion, because they can reflect first-excursion failure and cumulative plastic damage failure, respectively. Finally, field investigations in a blasting site in Zunyi, Guizhou province, China, are used to prove that compared to the PPV-frequency criterion the proposed energy-based dual safety criterion is more capable of assessing the damage potential of blast vibrations.

The fracture and fragmentation of rock materials are basic and important problem in geomechanics and blasting engineering. An approach, which can simulate the process of fracture and fragmentation of rock materials, is introduced in this work. A beam-particle model is first introduced in the frame of the discrete element method. In the beam-particle model, the neighboring elements are connected by beams. Consequently, a beam network is formed in the particle system. The strength characteristics of rock materials are reflected by the beam network. The strength criterion was then built to verify whether a beam exists or not. The process of rock fracture and fragmentation is described by the gradual disappearance of beams. Finally, two cases were presented to indicate the validity of the method proposed in this work.

Based on cutting principle and technology development of vertical blasthole cut by stage and deck in vertical shaft excavation, combined with the merits of middle space charging and toe space charging, the reinforced cutting effect of central large-diameter blasthole and the method of cutting blast by stage and deck toe space charging for the vertical large-diameter blastholes was put forward and analyzed theoretically. This new cut blasting method is provided with the advantages of high blasthole using ratio, big cavity bulk, low rate of chunk, even lumpiness, and relatively high energy using ratio. The parameter choices and practical effects of this cutting method were discussed after in situ experiment. It shows that the decked delay time of 75~100 ms is applicable.

In order to study the mechanical behavior of open caisson foundation in the Wenzhou area, combined with the characteristics of the soil layer in the Wenzhou area, based on the field measurement and investigation of a wide range of engineering cases, this project studies the mechanical properties of open caisson sinking in soft soil stratum and optimizes the construction parameters through the combination of field measurement, numerical simulation, and theoretical calculation, while ensuring the smooth sinking of the open caisson, control the deformation effect of the soil around the open caisson to serve the urban construction. The research results can directly serve the whole process of design, construction, measurement, and control of open caisson engineering. It has engineering practical significance and can be used as a reference for similar projects.