Dynamic Stress Concentration of Underground Lined Cavities in Different Distance under Incident Plane SV Wave

A series solution for dynamic stress concentration of underground lined cavities in different distance under incident plane SV waves is given by wave function expansion method. The infinite series is cut and calculated under the required precision. The lining includes rigid lining, unlined cavities, flexible lining. The numerical results show that the distance between cavities has an important impact on the dynamic stress concentration factor and the interaction between two cavities greatly amplifies the dynamic stress concentration. With the distance increases the dynamic stress concentration factor turn smaller gradually and tend to the distribution case of one cavity; The rigidity of lining also has great effect on the dynamic stress concentration which is highest for the rigid lining, second for unlined cavities and is lowest for the flexible lining.

Microearthquake crustal reflections, Socorro, New Mexico

About 25 per cent of the microearthquakes which originate close to Socorro (S minus P ≦ 2.5 secs) produce seismograms with two sharp arrivals about 2.5 and 5.0 seconds after the direct S-phase arrival. The best interpretation of the time-distance data for these late phases is that they are the SxP and the SxS reflections from a crustal discontinuity at a depth of 18 km. The amplitudes of the reflections, which average 0.21 and 0.32 of the direct S-phase amplitude on vertical-component seismograms, are for greater than theoretical amplitudes found by assuming uniform radiation from the focus and reflection of a plane SV wave from a horizontal discontinuity.