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中国北方春秋季节常有滑坡发生。秋季发生的滑坡多由降雨引起,初春发生的滑坡多由冻融引起。这种冻融作用触发的滑坡在甘肃省黑方台地区最为典型。为了研究冻融诱发滑坡的基本特征和破坏机制,对黑方台地区的滑坡进行了现场调查,并对典型滑坡进行了地表温度和孔隙水压力的检测,在室内进行了偏应力不变、平均有效应力逐渐减小的三轴剪切试验来反映孔隙水压力逐渐增大时黄土的强度特性。结果表明:冻融作用分为冻结期、冻融期和融化期3个时期。冻结期使得地下水排泄受阻,坡体内孔隙水压力增大,土体抗剪强度降低,进而降低了边坡稳定性;融化作用使地下水突然释放,产生很高的水力梯度,也降低了斜坡的稳定性,最终导致滑坡发生。
Spring and autumn seasons in northern China often occur landslides. The landslides that occurred in autumn were mostly caused by rainfall. The landslides occurred in early spring were mostly caused by freezing and thawing. This kind of freeze-thaw triggered landslide is the most typical in Heifangtai area of Gansu Province. In order to study the basic characteristics and failure mechanism of landslides triggered by freezing and thawing, the landslides in Heifangtai area were investigated on site, the surface temperature and pore water pressure of typical landslides were measured, and the deviatoric stress was constant in the interior. The average The triaxial shear test with decreasing effective stress reflects the strength characteristics of loess when the pore water pressure is gradually increasing. The results showed that the freeze-thaw cycles were divided into three phases: freezing, thaw and thawing. During the freezing period, the discharge of groundwater is blocked, the pore water pressure in the slope body increases, and the shear strength of the soil decreases, which in turn reduces the stability of the slope. The melting effect causes a sudden release of groundwater, resulting in a very high hydraulic gradient and also reduces the stability of the slope Sexuality eventually led to landslides.