Abstract
With the development of tunnels and other engineering constructions into the deep strata, rock masses are more prone to dynamic damage such as rock bursts under in situ conditions and excavation disturbances. The pore water in the rock mass will produce pressure changes during this process. According to the relationship between the change of pore water pressure and the development of rock mass damage, the variation rule and precursor characteristics of pore water pressure in the process of rock mass failure can be found. In this paper, through mechanical analysis, the evolution law of pore water pressure during the failure process of saturated rock is obtained. The study found that, in the process of rock failure, the pore water pressure presents three stages of linear growth, transition, and decrease. The rise and fall of pore water pressure are closely related to rock damage and influence each other. Through the observation of pore water pressure during coal mining, it is found that the coseismic effect of pore water pressure is significant. It is proved that there is a close correlation between the evolution of the stress field in the surrounding area of the stope and the change of pore water pressure in the surrounding area under the effect of mining disturbance. During the engineering practice, dynamic monitoring can be carried out on the change of pore water pressure inside the rock mass according to the law, and the precursor information of rock mass instability and failure can be explored.
Highlights
Research shows that the complete process of a seismic event is carried out within a certain range of time and space. e source of the earthquake includes the ruptured body that generates rupture and instability and consumes energy when the earthquake occurs and the surrounding participants that provide energy for the earthquake
Since the selection of the observation station is far from the working faces and the location where rock bursts occur, the change of pore water pressure obtained changes with the change of the stress field in the adjacent area of the closed rock mass. is change presents obvious characteristics of microdynamic changes, which proves that there is a close correlation between the evolution of the stress field in the surrounding area of the stope under mining disturbance and the change of the pore water pressure in the surrounding area
(1) In an ideally closed saturated rock unit, the pore water pressure is closely related to the expansion of internal damage. e pore water pressure presents a linear increase, a growth-decrease transition, and a decrease process and reaches a stable value after the rock is completely destroyed
Summary
Research shows that the complete process of a seismic event is carried out within a certain range of time and space. e source of the earthquake includes the ruptured body that generates rupture and instability and consumes energy when the earthquake occurs and the surrounding participants that provide energy for the earthquake. The stress of the rock mass and the pore water pressure will increase during the compression process If it is a permeable stratum, the excess pore water pressure will dissipate over time and cause the change of groundwater level. E “stress-strain” curve shows that the rock deformation enters the plastic stage, and the pore water pressure increases slowly and decreases after reaching the peak. According to the principle of effective stress (see formula (3)), during the damage, the pore space inside the rock becomes larger, and the pore water pressure decreases. When the total stress σ remains constant, the pore water pressure p decreases, which in turn causes an instantaneous increase in the effective stress and intensifies the development of damage cracks in the rock. E study of the pore water pressure change can be used to Stress Damage Pore water pressure
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