TANG Xin,ZHANG Wuyu,TONG Guoqing,et al.Experimental Study on Dynamic Characteristics of Loess in Xining Area under Freeze⁃thaw Cycles[J].Journal of Disaster Prevention and Mitigation Engineering,2023,43(04):887-895.
TANG Xin,ZHANG Wuyu,TONG Guoqing,et al.Experimental Study on Dynamic Characteristics of Loess in Xining Area under Freeze⁃thaw Cycles[J].Journal of Disaster Prevention and Mitigation Engineering,2023,43(04):887-895. DOI: 10.13409/j.cnki.jdpme.20211111047.
Experimental Study on Dynamic Characteristics of Loess in Xining Area under Freeze⁃thaw Cycles
As a kind of special soil widely distributed in Qinghai Province, loess has long been impacted by both freeze-thaw cycle and seismic loading. The seismic susceptibility and water sensitivity of loess have been widely discussed. Taking loess in Xining area as the research object, the change rule of dynamic properties of loess under the coupling effect of freeze-thaw cycle and dynamic load was studied. The dynamic triaxial test with cyclic dynamic load in the form of sinusoidal wave was carried out, and the evolution laws of perimeter pressure, the number of freeze-thaw cycles and the amplitude of dynamic shear strain
γ
d
on the backbone curve of loess, the dynamic shear modulus
G
d
, the dynamic shear modulus ratio
G
d
/
G
d max
, and the damping ratio
λ
were analyzed. The results show that: the backbone curve of loess tends to be stabilized after 6 freeze-thaw cycles, and the development process of the backbone curve can be divided into elastic and elastoplastic stages; the dynamic shear modulus curve is fitted by Hardin-Drnevich model and improved Hardin-Drnevich model respectively, and it is found that the dynamic parameters are fitted better with the improved Hardin-Drnevich model; with the reduction of the perimeter pressure, the distribution of
G
d
/
G
d max
-
γ
d
relationship curve is more dispersed and has a tendency to decrease gradually; with the increase of
γ
d
,
λ
is increasing; after the loess experiences different numbers of freezing and thawing cycles, there are maximum and minimum values of
G
d
/
G
d max
and
λ
under various conditions of perimeter pressures. This study provided a preliminary understanding on the dynamic parameters of loess in the Qinghai region under the action of freeze-thaw cycle, and the research results can provide references for seismic design in cold regions.
关键词
Keywords
references
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