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通过多种类型的快剪试验,全面把握塔克拉玛干沙漠风积沙的剪切变形特征。试验结果表明:风积沙的剪切变形曲线明显受相对压实度影响——后者低于95%时基本上不出现峰值,高于95%时常会出现峰值,并随压实度或垂直压力的增大,峰值抗剪强度与残余抗剪强度的差值也加大;残余抗剪强度受压实度、垂直压力、含水率的影响较小,一般较高,多在峰值抗剪强度的90%以上,表明风积沙具有比较明显的剪胀性与剪缩性;试验时不饱水,出现峰值时的剪应变多在0.8%~1.6%之间,试验时饱水则会明显增加,并导致剪切变形曲线不易出现峰值等。机理在于压实度与含水率变化所导致的毛细管力与薄膜水连接的复杂变化及其综合影响。
Through various types of quick shear tests, the shear deformation characteristics of the aeolian sand in the Taklamakan Desert are fully grasped. The results show that the shear deformation curve of aeolian sand is obviously affected by the relative compaction degree - the latter basically does not appear peak value when the latter is less than 95%, the peak value often appears when it is higher than 95%, and with the compaction degree or vertical The difference between the peak shear strength and the residual shear strength increases with the increasing of the pressure. The residual shear strength is less affected by the compaction degree, the vertical pressure and the moisture content. Generally, the shear strength at peak shear strength Of the above 90%, indicating that Aeolian sand has obvious dilatancy and shear-shrinkability; test is not full of water, the peak shear strain increased more than 0.8% to 1.6%, the test will be full of water will be obvious Increase, and lead to shear deformation curve is not prone to peak and so on. The mechanism lies in the complex changes of the capillary force and the membrane water connection caused by the changes of the compaction degree and the moisture content and their combined effects.