Base Stress of the Opened Bottom Cylinder Structures

The base stress of the opened bottom cylinder structure differs greatly from that of the structure with a closed bottom. By investigating the inner soil pressure on the cylinder wall and the base stress of the cylinder base, which were obtained from the model experiments, the interactions among the filler inside the cylinder, subsoil and cylinder are analyzed. The adjusting mechanism of frictional resistance between the inner filler and the wall of the cylinder during the overturning of the cylinder is discussed. Based on the experimental study, a method for calculating the base stress of the opened bottom cylinder structure is proposed. Meanwhile, the formulas for calculating the effective anti-overturning ratio of the opened bottom cylinder are derived.

Joint inversion of gravity and multiple components of tensor gravity data

Geological structures often exhibit smooth characteristics away from sharp discontinuities. One aim of geophysical inversion is to recover information about the smooth structures as well as about the sharp discontinuities. Because no specific operator can provide a perfect sparse representation of complicated geological models, hyper-parameter regularization inversion based on the iterative split Bregman method was used to recover the features of both smooth and sharp geological structures. A novel preconditioned matrix was proposed, which counteracted the natural decay of the sensitivity matrix and its inverse matrix was calculated easily. Application of the algorithm to synthetic data produces density models that are good representations of the designed models. The results show that the algorithm proposed is feasible and effective.

Dynamic response of gravity dam model with crack and damage detection

Gravity dam is a typical structure that has been frequently used in the fields of water conservancy engineering, and the safety of the structure has received widespread attention recently. Due to earthquakes or other reasons, gravity dams normally have damage such as cracks in practical service. Damage in the structures can alter the structural dynamic behavior and seriously affect structural performance. Maintaining safety and integrity of the gravity dam structures requires a better understanding of dynamic response of structure with damage and associated damage detection method. In order to study thoroughly the dynamic behavior of gravity dam with damage, the sweep vibration responses of the gravity dam with and without damage are investigated. The experimental results show that the peak-peak acceleration responses all increase for the structure is with crack. At the same time, a structural damage detection method, i.e., the local damage factor (LDF) method, is considered in the study of gravity dam damage detection when the dam is subjected to the base excitation. It is shown that the LDF method can be used as a damage index and is capable of evaluating both the presence and relative severity of structural damage, and it can be used as a viable condition assessment and damage identification technique to detect and quantify the damage in the gravity dam.