| Laboratory tests on simulated earthquake Seed usually simplified analysis, this method means the equivalent number of cycles equivalent of seismic waves as a certain number of cycles of uniform shear stress, and then in the dynamic triaxial test was anti-sand liquefaction based on the shear stress, compared to the actual seismic shear stress and shear stress on liquefaction of sand in order to determine whether the liquefaction of saturated soils. Since the introduction, this method is widely used in practical engineering applications. In recent years, in large cities around the frequent occurrence of strong earthquakes, such earthquakes commonly known as the city of epicentral earthquake. Found, Seed equivalent method from metal fatigue problems Palmgren-Miner cumulative damage hypothesis, applied to the city of strong ground motion simulation of a direct type with obvious limitations, is no longer reasonable. In this regard, the paper based on a real case of seismic wave analysis of dynamic characteristics of saturated sand to verify the applicability of the theory Seed. Then the wave of the earthquake sequence, symmetry, frequency and other factors were studied. Finally, explore saturated sand in the past when the ground motions calculated the cumulative strain.After the initial comparison of test results showed that relative to the near-field far-field earthquake frequency components larger earthquake, the peak appeared earlier. Equivalent to the classical method of ground motion simulation using harmonic near-field irregular large pulses of strong ground motion, the seismic load is too simplistic, rougher, does not reflect the actual situation of seismic response of soil, there is need for improvement. Seed et al, and the equivalent rule is based on the physical location of a large number of results obtained, the soil can only say that the results of disaster, catastrophe cannot describe the process of soil. And the test results table order on soil strength have a greater impact. Frequency factor in the comparison of this test has little effect can be neglected.On this basis, the cumulative damage theory and this paper describes the various damage cumulative theory that rule with the damage curve established under irregular waves damage model can simulate the dynamic behavior of soil under earthquake ground motion. Damage model in MATLAB preparation procedures and irregular sine wave based program to calculate the cumulative strain compared with the experimental results to verify the correctness of the calculation method. Finally, the rain flow method based on simplified methods of irregular wave and irregular wave compiled MATLAB program to achieve a simplified, streamlined obtained by the load consisting of a series of sine wave. Finally, the simplified rules of random wave calculated with the total compared with experimental results to verify its correctness. |
