In modern daily life, people are often exposed to many types of vibrations generated by machine operations, traffic and other human activities. These vibrations can cause annoyance to residents, and even interfere the operations of precision instruments. Generally, these adverse effects of vibrations can be eliminated or prevented by installation of various types of wave barriers, such as multi-row of holes. In the paper, the investigation is focused on effects of using multi-row of holes for the reduction of nearby vibration response generated by dynamic machine foundation laid on saturated soil. Two semi-analytical BEM models are established to calculate the environmental vibrations due to the machine foundation and the vibration isolation efficiency by multi-row of holes, respectively. In order to increase calculating efficiency of the semi-analytical BEM, a simple SPMD parallel algorithm is developed using Matlab software. The SPMD parallel algorithm is optimized by using the corresponding relationship between holes on the spatial coordinates. By using the optimized SPMD parallel algorithm, the effects of the model parameters on effectiveness of vibration isolation are calculated and discussed in detail. The results show that the optimized SPMD parallel algorithm of semi-analytical BEM is much faster than the chained program dramatically. Multi-row of holes can isolate the ground vibrations successfully, and the holes layout has less effect on the screening efficiency. Increasing the radius and the number of holes in a row, decreasing the net spacing between two successive holes can all lead to an increase in the screening effectiveness, while the rows of holes and the net spacing between two successive rows have less effect on the screening effectiveness. Further, the distance between the rigid foundation and wave barriers can has a limited impact on vibration mitigation effectiveness. According to the results, it’s suggested in the design that two-row of holes is recommended and the hole depth, radius and the nest spacing between two successive holes should take the values of 1.0, 0.15 and 0.1, respectively.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |