Dynamic, In-situ, Nonlinear-Inelastic Response and Post-Cyclic Strength of a Plastic Silt Deposit
Dynamic, In-situ, Nonlinear-Inelastic Response and Post-Cyclic Strength of a Plastic Silt Deposit
复制标题
塑性淤泥沉积物的动态、原位、非线性非弹性响应和循环后强度
DOI：
10.1139/cgj-2020-0652
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发表时间：
2021
影响因子：
3.6
通讯作者：
Stuedlein, Armin W.
中科院分区：
文献类型：
--
作者：
Jana, Amalesh;Stuedlein, Armin W.
本研究提出使用受控爆破作为地震能量源来获得塑性粉砂沉积物的耦合、动态、线弹性到非线性非弹性响应。爆炸引起的地震动特征表明，剪应变和相应的残余超孔隙压力（EPP）与地震频率范围内的低频近场和远场剪切波相关，而高频纵波的影响可以忽略不计。使用三个爆破程序来建立剪切应变、EPP 和非线性剪切模量退化之间的初始应变和预应变关系。引发土壤非线性和触发残余 EPP 生成的初始阈值剪切应变范围分别为 0.002% 至 0.003% 和 0.008% 至 0.012%，其中后者对应于最大剪切模量 Gmax 的~70%。在淤泥沉积物内 EPP 预应变和消散后，触发残余超孔隙压力所需的剪切应变增加了两倍。在给定剪切应变幅度下，与完整的直接简单剪切（DSS）测试样本相比，现场观察到更大的超孔隙压力。使用叶片剪切试验测量的爆炸诱发 EPP 场内原位不排水剪切强度的降低与 DSS 测试样本的结果相比更为有利。
This study presents the use of controlled blasting as a source of seismic energy to obtain the coupled, dynamic, linear-elastic to nonlinear-inelastic response of a plastic silt deposit. Characterization of blast-induced ground motions indicates that the shear strain and corresponding residual excess pore pressures (EPPs) are associated with low-frequency near- and far-field shear waves that are within the range of earthquake frequencies, whereas the effect of high-frequencyP-waves is negligible. Three blasting programs were used to develop the initial and pre-strained relationships between shear strain, EPP, and nonlinear shear modulus degradation. The initial threshold shear strain to initiate soil nonlinearity and to trigger generation of residual EPP ranged from 0.002% to 0.003% and 0.008% to 0.012%, respectively, where the latter corresponded to ∼70% of the maximum shear modulus,Gmax. Following pre-straining and dissipation of EPPs within the silt deposit, the shear strain necessary to trigger residual excess pore pressure increased two-fold. Greater excess pore pressures were observed in situ compared to those of intact direct simple shear (DSS) test specimens at a given shear strain amplitude. The reduction of in situ undrained shear strength within the blast-induced EPP field measured using vane shear tests compared favorably with that of DSS test specimens.