高含盐粉土的力学特性试验研究

高含盐粉土不仅含盐量较高,而且黏粒含量极低,粉粒含量高,级配不均匀,导致难以压实,强度低。为了了解此类特殊粉土的力学特性,在室内物理化学性质分析的基础上,进行原位旁压试验和原状土样的三轴试验,充分分析了高含盐粉土的力学性质。高含盐粉土的可溶性盐含量高达2.9%,主要是高硅、铝,水溶盐以Cl-和Na+为主,属氯盐碱性土。旁压试验结果表明,临塑压力可取350kPa、极限压力可取500kPa、旁压模量Em可取1750kPa、剪切模量Gm可以700kPa作为参考值。室内力学试验进一步分析表明,该土体具有较强的剪胀性,在轴向应变达到12%左右时,试样达到稳态状态。围压150kPa下的峰值强度能达到600～800kPa,残余强度也能达到450～550kPa。

Experimental study of mechanical properties of saline silt

Saline silt has many special characteristics, such as high salt content, extremely low content of clay and uneven gradation. Due to these special properties, it is hard to compact, so that the strength is very low. In order to understand mechanical characteristics of saline silt, in-situ pressuremeter tests (PMT) and triaxial tests of undisturbed samples were conducted after physico- chemical analysis of this saline silt. The tests results show that the content of soluble salt is 2.9%, and the main ingredients are Cl－ and Na＋. The silt belongs to alkaline soil with chlorine saline. The PMT test results indicate that pre-plastic pressure is 350 kPa and limit pressure is 500 kPa. In that area, pressuremeter and shear modulus can be adopted by 1 750 kPa and 700 kPa respectively. Laboratory test results represent that this soil have strong dilatancy effect. When the axis strain reaches to 12%, the sample will be close to steady state. The peak and residual strength can be achieved to 600~800 kPa and 450~550 kPa respectively when the confining pressure is 150 kPa.