The mechanical behaviors were investigated by nonlinear creep tests of poly(methyl methacrylate) under different temperatures. The test duration was 4000 seconds. The corresponding temperature shift factors, stress shift factors and temperature-stress shift factors were obtained according to time-temperature superposition principle, the time-stress superposition principle and the time-temperature-stress superposition principle (TTSSP). The master creep compliance curve up to about 1-month at a reference temperature 22 degrees centigrade and a reference stress 14 MPa was constructed, and the effect of stress-induced damage evolution on the long-term creep behavior of polymeric material was accounted. It was shown that TTSSP provides an effective accelerated test technique in the laboratory, the results obtained from a short-term creep test of poly(methyl methacrylate) specimen at high temperature and stress level can be used to construct the master creep compliance curve for prediction of the long-term mechanical properties at relatively lower temperature and stress level, and the master creep compliance curve with damage considered can be applied to accurately characterize the long-term creep behavior of nonlinear viscoelastic polymer.

In this paper, the straight-wall-arch structure in the rock medium is taken as the research object, and the high-pressure plane charge loading test technology is adopted to study the anti-explosion performance of different types of structures under the explosion loading. Three types of structures, which are individually built with the high-performance reinforced concrete, the C30 reinforced concrete, and the C30 reinforced concrete with a foam concrete backfill layer as well, are tested, and the dynamic responses and damage characteristics of these structures are investigated. The test results show that under the condition of the same plane charge explosion loading, in the vault of the high-performance reinforced concrete test section appears a through-tensile crack with a largest transverse relative displacement between the two straight walls, and the composite structure test section only shows an intermittent crack at the arch foot, which represents a slight damage mode. Meanwhile the arch spring of the C30 reinforced concrete test section suffers a through-compression shear failure with a largest vertical relative displacement between the vault and the floor, which represents a moderate damage mode. Therefore, adopting the high-performance reinforced concrete, and the C30 reinforced concrete with the foam concrete backfill layer, can effectively decrease the damage degree of the rock structures. Compared with the C30 reinforced concrete, the high-performance reinforced concrete can improve the resistance of the structure by improving the structural strength and strengthening its capacity to absorb waves and energy dissipation, and the foam concrete backfill layer can significantly reduce the lateral and vertical relative displacement of the structural free surface and the peak stress of the structural inner layer. The composite structure test section of the C30 reinforced concrete with foam concrete backfill layer appears to be an excellent anti-explosion performance property.