Tweet Share

• Send by email

  Send by email

  

  Assessment of mutual influence of underground constructions on electromagnetic radiation emitted by fractured rock

  In course of experimental registration natural electromagnetic radiation emitted by fractured rock mass inside underground building sites of Moscow subway system some new own-development equipment (EMI-3K) was applied. EMI-3K apparatus was developed by SJC ‘Lenmetrogiprotrans’ (scientific and research department) with the aim of impulse-electromagnetic-radiation registration in frequency range from 1 kHz to 250 kHz in three spatial dimensions. The results obtained during these experiments indicate capabilities of the equipment and the NEMR method (natural electromagnetic radiation registration method) to assess the mutual influence of underground constructions which are cross each other in different levels. The main anomalies of NEMR were marked on the line of registration in upper tunnel and presumably coincided with zones of abutment pressure distribution from deeper tunnel. Abutment pressure in rock mass arises as a result of the creation of cavities such as tunnels and determines the processes of redistribution of the stress-strain state (SSS) occurring in the marginal parts of the massif near the excavations. Such redistribution of SSS is especially active when the tunnels are close to each other. It creates conditions for mutual influence (imposition) of the abutment pressures, which under certain conditions of the depth of their formation leads to the deformations of the rock mass between the tunnels. On a section of rock mass between tunnels corresponding to the boundary of the transition from irreversible deformations to elastic ones the abutment pressure reaches a maximum and then gradually decreases to values corresponding to the initial state. Thus, rocks in the array between the tunnels can experience irreversible deformations. There are mutual displacement of particles and blocks, deformation and growth of micro and macro cracks in rock mass. All this leads to the generation of electromagnetic pulses that can be detected by the NEMR method. Due to the obtained results, one of the promising direction of scientific research activity in department is an operative assessment of the mutual influence of the objects which are under construction and existing (both underground and located on the surface) on the electromagnetic radiation of the enclosing rock massif. Underground constructions, Natural electromagnetic radiation, Stressstrain state, Abutment pressure, Mutual influence.

  Recipient :

  Name ^* :

  E-mail address ^* :

  ^* Required fields

  Send   or  Cancel

• Print