关键词: 侵蚀率和后退速率, 黄土, 人工坡面, 断层崖

Abstract: The degradation of fault scarps in unconsolidated deposits can be accurately simulated. Under the appropriate correction,high-accuracy digital models can be built for the fault scarps evolution. These models provide the basis for estimating the age of faulting. In this paper we measured a series of artificial fault scarps with different slope angles in frequency of once a month,and found that the artificial fault scarps with slope angle above 30° are in an unstable stage and a group of parameters are acquired. There are obvious differences in erosion thicknesses,daily erosion rates and annual recession rates of artificial fault scarps. Besides the greatest erosion thickness of 6.13mm on the slope of 80°,there is a peak value of 5.24mm at the scarp of 50°,and the erosion thicknesses then gradually reduce for other slopes. There are the similar distribution characters in the daily erosion rates and the annual recession rate. Besides the recession rate of (6.74±0.26)mm/a on the slope of 80°,the greatest value of (7.41±0.84)mm/a is observed at the scarp with slope angle of 50°.But there is an abnormally high value of (8.19±1.16)mm/a in recession rate for scarps with a slope of 30°,which may result from the low angle. As the angle reduces,the deviation of the erosion thickness from the recession distance becomes bigger. The average recession rate of 5.8mm/a can be used as the correction value of the evolution of the normal fault scarps in Shanxi rift system,though it is based on the measurement of one year and has larger limitations. In addition,there is an obvious difference between field observations and ideal model. The accumulation amounts at the foot of scarps are not equal to the erosion amounts of scarp surface,due to that part of weathering material was washed away by the rainwater. The experimental observations show that there are not obvious accumulations during the rainy season(until October)due to rushing of rainwater,but the loess accumulations appear at the foot of scarp after the snow melts in winter. According to the measurements of one year,41.6% of total erosion amount is washed away by rainwater at the scarp with slope angle of 80°,and for others scarps the results are 52.4%,47.6%,50.6%,60.5% at slope angles of 70°,60°,40°,respectively.

Key words: erosion rate and retreat rate, loess, man-made slope, fault scarp