Sandbox Physical Simulation Experiment of Extensional Structure under Different Stretching Modes and Speeds

Sandbox structural physics simulation experiment is an efficient method to simulate the deformation process, genesis mechanism and dynamic process of natural structural deformation in laboratory. Factors affecting the rate of rock deformation and the mode of action of forces are the main factors affecting the results of physical simulation experiments of extensional tectonics and tectonic morphology. Based on this, in order to investigate the effects of tensile speed and tensile mode (mode of the stress action) on extensional structural deformation characteristics in sandbox physical simulation experiment. This article is based on existing research, three different stretching speeds of high (0.01 mm/s), medium (0.001 mm/s) and low (0.000 5 mm/s) are combined with two different stretching methods of unidirectional and bidirectional stretching, and six sets of experiments are designed for comparative study. The results show that: ① Tensile velocity has no significant effect on the final morphology of the sand body, but has a certain influence on the development process of the fault, while the influence of the tensile mode on both the development process and the final morphology of the fault is more significant, and the velocity of the sand body increases to a certain high value before the formation of the fault and decreases rapidly after the formation of the fault. ② The sand body of the unidirectional stretching model eventually forms an asymmetric graben tectonic feature. The sand bodies of the two–way stretching model eventually form a typical graben tectonic feature. ③ Asymmetric graben structures are usually formed in a relatively stretched or differentially stretched environment, with a series of stepwise positive faults on the relatively stretched side and a large positive fault on the relatively fixed side, and the location of the pre–existing structure often determines the initial location of the later structure development. This understanding lays the foundation for the model setting and parameter selection in sandbox analogue modeling of the extensional structure.