Soil Dynamics and Earthquake Engineering ( IF 4 ) Pub Date : 2021-03-27 , DOI: 10.1016/j.soildyn.2020.106535 Vlado Gičev , Mihailo D. Trifunac , Maria I. Todorovska
We study how the peak velocity of an SV-wave pulse on the ground surface of a two-dimensional soil valley is reduced by loss of wave energy during large nonlinear response inside the valley. This is a follow-up on our previous studies in which we considered excitation by an SH-pulse and a P-wave pulse. We consider in-plane response for incident angle below critical and assume that the soil material does not support tension, but the normal stress at a point in the soil can be compression. A point in the soil with zero stress behaves as stress-free, does not transmit normal stress and appears as a crack. We study the interplay of two opposing effects. The first effect is a jump in impedance from a higher value (in the half-space) to a lower value (in the valley), which amplifies the linear motions at the free surface of the valley. The second effect is the occurrence of nonlinear zones in the valley, which reduce the motion at the valley surface. We show how, for small excitations, when the response is linear or almost linear, the valley amplifies the motion. As the excitation amplitudes increase, at low frequencies, at which the nonlinearities are weak, the effect of decrease in impedance is stronger than the effect of nonlinear zones and the valley amplifies the motion. At higher frequencies, the effect of nonlinearity becomes stronger and the amplitudes of motion are reduced. As the excitation further increases, the effect of nonlinear soil response prevails at all frequencies and the motion is reduced significantly.
中文翻译:
通过非线性土壤响应降低峰值地速– III:SV波脉冲激励
我们研究了二维波谷地表上SV波脉冲的峰值速度如何在波谷内部发生较大的非线性响应时,由于波能的损失而降低。这是我们先前研究的后续研究,其中我们考虑了SH脉冲和P波脉冲的激发。我们认为入射角低于临界值时会产生平面响应,并假定土壤材料不支持张力,但土壤中某个点的法向应力可能会被压缩。零应力土壤中的一点表现为无应力,不传递法向应力,并显示为裂缝。我们研究了两种相反作用的相互作用。第一个效果是阻抗从较高的值(在半空间中)到较低的值(在凹部中)跳跃,这放大了凹部自由表面处的线性运动。第二个效果是在山谷中出现非线性区域,从而减少了山谷表面的运动。我们展示了对于小激发,当响应为线性或几乎线性时,谷如何放大运动。随着激励幅度的增加,在非线性弱的低频处,阻抗减小的影响要强于非线性区域的影响,并且谷值会放大运动。在较高的频率下,非线性效应变得更强,运动幅度减小。随着激励的进一步增加,非线性土壤响应的影响在所有频率上都普遍存在,并且运动显着降低。当响应为线性或几乎线性时,谷底会放大运动。随着激励幅度的增加,在非线性弱的低频处,阻抗减小的影响要强于非线性区域的影响,并且谷值会放大运动。在较高的频率下,非线性效应变得更强,运动幅度减小。随着激励的进一步增加,非线性土壤响应的影响在所有频率上都普遍存在,并且运动显着降低。当响应为线性或几乎线性时,谷底会放大运动。随着激励幅度的增加,在非线性弱的低频处,阻抗减小的影响要强于非线性区域的影响,并且谷值会放大运动。在较高的频率下,非线性效应变得更强,运动幅度减小。随着激励的进一步增加,非线性土壤响应的影响在所有频率上都普遍存在,并且运动显着降低。非线性的影响变得更强,运动幅度减小。随着激励的进一步增加,非线性土壤响应的影响在所有频率上都普遍存在,并且运动显着降低。非线性的影响变得更强,运动幅度减小。随着激励的进一步增加,非线性土壤响应的影响在所有频率上都普遍存在,并且运动显着降低。