The Effect Of Inputting Interface Of Earthquake Wave On The Seismic Parameters Of Ground Motion

The selection of inputting interface of earthquake wave is a very important step to construct the site calculation model. Inputting interface of earthquake wave is also a very important parameter to analyze the seismic ground motion of the site. In fact, inputting interface of earthquake wave is the top of soil layer that is considered as true rock. In the present codes, for the work to evaluate the site, they choose the top of the soil layer which shear wave velocity is 500m/s or 700m/s as inputting interface of earthquake wave. At present, it usually surveys the site condition to ascertain inputting interface of earthquake wave. But sometimes, a lot of difficulties will be encountered to finish this work. So, the effects of the inputting interface of earthquake wave on the results of soil layer seismic response attract lots of attentions. In order to solve this problem, the following problems are studied in this thesis.1. The study is summarized in detail on the inputting interface of earthquake wave and other site conditions be related to the inputting interface of earthquake wave. Some methods of the present codes and regulations to ascertain inputting interface of earthquake wave are introduced.2. Based on hundreds of actual site profiles, the author select and create several representative drilled-holes. All of these site profiles have both geological and engineering features, the site calculation model and the calculation data is also ascertained. An idea is presented to study the effect of inputting interface of earthquake wave on the seismic ground motion in detail by using one-dimension equivalent linearization programs and site profiles.3. The ground peak acceleration, platform height and characteristic period of different inputting interfaces of earthquake wave and earthquake inputs are calculated. When the intensity earthquake inputs are small(the peak is 10gal,50gal or 120gal), it is found that when the shear wave velocity of the inputting interfaces of earthquake wave change between 300m/s and 500m/s, to the four types of sites ascertained by aseismic codes, the three earthquake ground motion parameters change little, contrasted with the results of the inputting interface of earthquake wave that is considered as true rock, the relative error is less than 30%. When the intensity earthquake inputs are great(the peak is 250gal,300gal or 400gal), the three earthquake ground motion parameters of sites belong to the second type and the third type change greatly with the change of the shear wave velocity of the inputting interface of earthquake wave, while the three earthquake ground motion parameters of sites belong to the first type and the fourth type change little. 4. The overburden soil layer keeps still, while the shear wave velocity of the inputting interfaces of earthquake wave change between 500m/s and 800m/s, the three earthquake ground motion parameters change little, and the more softer the site is, the more less the three earthquake ground motion parameters change.5. The ground peak acceleration, characteristic period and platform height of different inputting interfaces of earthquake wave and earthquake inputs of soil layer that contains soft soil layer are calculated. It is found that soft interlayer have great effect on the earthquake ground motion parameters, so the inputting interface of earthquake wave should be ascertained under the unwonted soil layer, it will be useful to diminish earthquake wave. To each type of sites, the author gives the range of the shear wave velocity of inputting interfaces of earthquake wave. At last, the author summarizes the problems that are encountered during the process of the research, and the following research is also pointed out.