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摘要:
黄土斜坡因湿陷所致侧压力促进坡体失稳滑动，是研究灌溉诱发黄土滑坡的基础科学问题。本研究通过黑方台黄土湿陷试验和坡体稳定性模拟，阐明了灌溉湿陷侧压力在坡体内部空间变异性及其促滑机理。结果表明，该区黄土为自重湿陷性黄土，灌区0～15 m深度黄土为轻度湿陷，20～25 m深度黄土为中度湿陷，非灌区黄土均为强烈湿陷。当坡体含水率由4%增加到20%时，总位移以水平方向为主，水平方向总位移由12 mm增加至140 mm，侧压力系数逐渐增大。饱和状态下，发生湿陷变形时的最大侧压力达123 kPa，湿陷型侧压力系数增加达1.4倍。湿陷导致坡体上部产生拉应力，在滑坡后缘深度在5 m以下的土体产生湿陷裂缝，形成优势通道；坡体内部因压应力集中而产生指向临空面的侧向压力，循着坡肩湿陷裂缝向坡体内部扩张，并沿弧形软弱带发生剪切破坏直至失稳。考虑侧压力对滑坡的促进作用与实际情况更为吻合，完善了灌溉型黄土滑坡的影响因素的表征，有助于完善黄土滑坡诱发灾害理论，为黄土滑坡的精确预警提供参考。
Abstract:Loess collapse-type lateral pressure have a landslide-promoting effect in loess slope areas, which is a basic scientific problem in the study of loess landslides induced by irrigation. A study on collapse tests and slope stability simulations of loess were conducted. The variability of loess collapse-type lateral pressure in the Heifangtai area and its sliding mechanism has been analyzed. The results indicate that Heifangtai loess is self-weighted collapsible loess; soil of the irrigated area at depths of 0-15 m are slightly collapsible; soil at depths of 20-25 m are moderately collapsible loess, and the loess in the unirrigated area is highly collapsible. As the water content of the slope increases from 4% to 20%, the total slope displacement is predominantly horizontal, increasing from 12 mm to 140 mm, the lateral pressure coefficient also gradually increases. In saturated state, the maximum lateral pressure reaches 123 kPa when collapsible deformation occurs, the collapse-type lateral pressure coefficient increases of up to 1.4 times, and horizontal deformation is also correspondingly large. Collapse action leads to tensile stresses in the upper part of the slope, making it prone to collapse-type crack formation in the soil below the back edge of the landslide at depths of up to 5 m, resulting in dominant channels of surface water infiltration and forming landslide scarps. What’s more, lateral pressure pointing to the critical surface is generated inside of the slope due to the stress concentration, which expands to the interior of the slope along the collapse-type crack of the slope shoulder, and shear damage occurs along the curved weak zone until instability occurs. Considering that the promotion of landslides by lateral pressure is more consistent with the actual situation and can better characterize the influencing factors of irrigated loess landslides. The results of this research help to improve loess landslide–induced disaster theory, and provide reference for the precise early warning of loess landslide disasters.
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Key words:
- collapsibility /
- lateral pressure coefficient /
- water content /
- loess landslide
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表 1 土体材料强度及物理参数
Table 1. Material strength and physical parameter
土层类型 体积模量K（MPa） 剪切模量G（MPa） 粘聚力C（kPa） 内摩擦角φ（°） 密度ρ（kg/m3） 液限(%) 塑限(%) 马兰黄土 417 149 23 21.9 1470 22.90~28.21 11.17~19.94 离石黄土 588 226 41 27.5 1780 —— —— 
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