长江科学院院报2019，Vol.36Issue(1)：48-54,7.DOI:10.11988/ckyyb.20170739
四川理县欢喜村冰水堆积体降雨条件下变形机理研究
Deformation Mechanism of Outwash Deposit Body under Rainfall Condition in Huanxi, Lixian County, Sichuan Province
摘要
Abstract
The deformation mechanism and characteristics of outwash deposit body under rainfall condition are dif-ferent from those of rainfall-induced landslides. The study area is featured with characteristics of dry and warm val-ley climate, with small rainfall amount but large evaporation. Through water-soil chemical effect tests, mineral com-position detection, scanning electron microscopy ( SEM) , rainfall simulation and medium scale in-situ shear test, the structural damage mechanism of outwash deposit in water is examined, and the characteristics and amplitude of strength attenuation are also investigated. On this basis, the infiltration and saturation characteristics of groundwater and the change trend of pore water pressure are analyzed by using SEEP/W module. The deformation mechanism and process of outwash deposit body are concluded in summary in line with geoenvironmental conditions. Research results unveil that when outwash deposit contacts with water, the dissolution of mineral ( mainly gypsum) together with the rearrangement of mineral particles weakens the soil structure, which further develops and mitigates the in-teractions among large particles, and finally results in the dramatic attenuation of overall soil strength under the lu-brication and softening effect of water: the value of cohesion declines by 20. 6%, and internal friction angle by 34.1%. Moreover, due to the special geological condition of the study area, the effect of rainfall infiltration in gentle slope is better than that in steep slope; and the differences in saturation time, range and depth brings about the var-iation of soil strength. Besides, favorable free surface gives rise to creep deformation in the direction of the free sur-face in the front edge and tensile cracks in the back edge of deformed body, providing passage for rainfall infiltra-tion. Cumulative creep deformation diminishes the locked segment in the front edge of deformed body, and finally induces instability.关键词
冰水堆积体/结构损伤/强度衰减/变形机理/SEEP/W模块Key words
outwash deposit body/structural damage/strength attenuation/deformation mechanism/SEEP/W module分类
建筑与水利引用本文复制引用
冯文凯,白慧林,何山玉,周强,曾琇舒,祁昊..四川理县欢喜村冰水堆积体降雨条件下变形机理研究[J].长江科学院院报,2019,36(1):48-54,7.基金项目
中国华能集团总部支持项目(HNKJ16-H12) （HNKJ16-H12）
云南省马洪琪院士2016年自由探索项目(2016HA012) （2016HA012）
