ObjectiveIn view of the problems such as cumbersome modeling and long calculation time faced in the past when numerical simulation was used
ObjectiveIn view of the problems such as cumbersome modeling and long calculation time faced in the past when numerical simulation was used to study the dynamic response of rock mass under blasting loads, and the existing mine numerical software is unable to solve the analysis of the vibration response of each parameter of blasting stress waves. This paper proposes a "Structural dynamic response model analysis method", conducts exploratory research in this field to achieve the purpose of rapid calculation, and provides a new research idea for the study of rock mass dynamic response under blasting load disturbance.MethodsBy constructing a dynamic response calculation model for limestone pillars with weak interlayers and employing the concentrated mass method in structural dynamics, the weak interlayers, which possess relatively weaker mechanical properties, were simplified as viscoelastic elements, while the limestone portions were treated as rigid bodies. Subsequently, relevant parameters were input, boundary conditions were established according to specific criteria, and a program was developed using Matlab software by integrating the Newmark-β self-starting method within the time-domain stepwise integration approach. The validity of this methodology was confirmed through numerical simulations and corroborated by on-site monitoring data. Additionally, the influence of various factors on the structural dynamic response was systematically analyzed to ascertain its stable state. This approach offers significant advantages, including reduced computational time, efficient modeling, and precise external load inputs.Results and discussion The number of weak interlayers, the magnitude of stiffness and damping, as well as the frequency of blasting loads, affect the displacement and velocity response of the pillar containing weak interlayers. The number of weak interlayers is inversely proportional to the response amplitude. However, due to the lower strength of the weak interlayers, they are prone to damage while absorbing more energy. When other conditions are constant, the amplitude of the dynamic response decreases with the increase of the stiffness or damping of the weak interlayer, the response period decreases with the increase of stiffness, and the change of damping magnitude has no significant effect on the response period. The amplitude of the displacement and velocity response of limestone first increases and then decreases with the increase of the frequency of the blasting stress wave. Its time-history curve shows a "single peak" shape. When the frequency of the external load is close to the natural frequency of the rock mass, a maximum value occurs and resonance is prone to happen. The thickness, stiffness and damping of the interlayer affect the occurrence of resonance. Resonance lasting for 3 to 5 cycles will cause compressive failure of the pillar with weak interlayers. At the high-frequency stage, due to the existence of damping, vibration is more likely to attenuate.ConclusionsThis paper focuses on addressing the exposure of weak interlayers during limestone mining, and the dynamic response mechanism of such ore pillars under the action of blasting loads. By using the Newmark-β code program for calculation, the goals of short time consumption and high efficiency are achieved, which is basically in line with the actual situation and provides a new idea for the study of rock mass dynamic response under blasting excitation.
