Analysis of seabed dome and fracture formation induced by gas
When gas from a deep source in sediments breaks through surface fine-grained sediments,dif-ferent gas source pressures and stratum structures may lead to different degrees of seabed dome,and then cause different deformation and failure processes of fine-grained sediments,leading to different scale and types of geological disasters.To study the evolution characteristics of this process,the gas in-jection laboratory experiment and numerical simulation analysis of fine-grained sediments were carried out to observe the typical process of gas-induced soil heave,the change of excess pore water pressure in sediments,and the stress and strain changes under different degrees of sediments dome.Combined with previous studies on sediments deformation and gas-induced fracture theory,the experimental data were analyzed.It was found that(1)The elastic plate bending deformation theory could well describe the deformation process of fine sediment under constant pressure and uniform gas distribution;(2)Af-ter gas domed fine-grained sediments,the location of cracks was related to the critical pressure to form cracks and the size of the gas pocket at the bottom of the sediments.The dumper and fatter the gas pocket were,the more prone the edge of the gas pocket were to be failed with tensile;otherwise,the top of the fine sediments of the gas pocket was more likely to produce fracture.
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