青藏高原多年冻土区热融滑塌变形现场监测分析

为了了解青藏高原多年冻土区K3035里程热融滑塌体的变形特征,分别在未滑动土体、近滑塌前缘滑体中布设了2个变形监测孔,利用Geokon-603型测斜仪实施了近1 a的变形监测。结果表明,发育在平缓斜坡上的热融滑塌具有明显的变形特征,其位移主要发生在土层浅部,越往深部,位移越小,这一监测结果通过室内数值模拟得到了验证。将阳坡的K3035热融滑塌与阴坡的K3057热融滑塌体的变形做了对比监测,无论是滑塌体后缘还是前缘,前者的滑动变形均显著大于后者。而无热融滑塌发育的斜坡(青藏铁路DK1139)土体变形量极小,这种差异一方面说明了开挖是导致热融滑塌发生的直接因素,另一方面,由于热融滑塌的影响,其后缘相对稳定的原斜坡土体也处于相对较大的蠕变变形之中。

IN-SITU MONITORING AND ANALYSIS OF THAW SLUMPING AND DEFORMATION IN GENTLE SLOPING GROUND OF PERMAFROST SOILS ON QINGHAI-TIBETAN PLATEAU

To study the deformation characteristics of the thaw slumping body at the alignment of K3035 in permafrost area of Qinghai-Tibet Platean,two deformation monitoring boreholes were instrumented with Geokon-603 clinometers,and one borehole lay in the non-sliding soil body while the other lay in the front part of the slumping soil body.Monitoring results of nearly one year show that the thaw slumping body developed in the slope of small dip angle has obvious deformation and its displacement mainly occurs in shallow soil area and decreases with depth.The monitoring results were verified by numerical simulations.The monitoring data comparisons between the thaw slumping body at the alignment of K3035(southern slope) and that at the alignment of K3057(northern slope) were carried out.With reference to both the leading edge and the rear edge of the thaw slumping body,the deformation of the former thaw slumping body is always greater than that of the latter.While in the slope with no thaw slumping(at the alignment of DK1139 of Qinghai-Tibet railway) the deformation is very limited.The difference indicates that on the one hand excavation is the direct factor causing thaw slumping,and on the other hand,because of thaw slumping,the soil body at the rear edge of the slope which is relatively stable originally will experience relatively large creep.