银川平原粉细砂的压缩性

Compressibility of Silty Fine Sand in Yinchuan Plain

粉细砂在银川平原分布广泛,埋藏浅,土层深厚,是建筑物的主要持力层,考虑干密度和饱和度两个重要因素,设计正交试验方案,研究了银川平原粉细砂的压缩性,探索各因素的作用规律和作用机理。研究结果表明:银川平原地表下1~7 m范围内,砂土的压缩性较低,压缩系数a1-2最大的不过0.2 MPa^-1,为中低压缩性土。压缩性随干密度的增大呈非线性减小,压缩性的降幅亦随干密度的增大而减小。压缩性随饱和度的增加呈非线性增大,但压缩性的增幅随饱和度的增大而减小。对于a1-2,干密度的影响很显著,饱和度的影响显著,提高干密度是降低银川砂土压缩性非常有效的措施,而提高饱和度对提高银川砂土的压实性有较好效果。建立的压缩性关系模型,相关性好,显著性高,对银川平原砂土压缩性的预测具有实际意义。

The shallow buried and thick silty fine sand is widely distributed in Yinchuan Plain.It is the main load bearing layer for building structures,and the mechanical properties test data for engineering reference are not enough.Therefore,considering the two important factors such as the dry density and the saturation,the statistical orthogonal test scheme was designed in this study.The compressibility of silty fine sand in Yinchuan Plain was studied by means of one-dimensional tests by using automatic pneumatic consolidation apparatus.The influence factors and mechanism of each factor were investigated,the significance was analyzed,and the empirical correlation with the compressibility was established.The results show that the compressibility of the silty fine sand is low,and the maximum value of a1-2 is no more than 0.2 MPa^-1 within 1~7 mdepth of Yinchuan Plain,which is a medium-low compressibility soil.With the increase of dry density,the compressibility decreases nonlinearly,and the change of compressibility decreases.With the increase of saturation,the compressibility increases nonlinearly,but the change of compressibility decreases.For a1-2,the effect of dry density is very significant,and the effect of saturation is significant.The order of significance is dry density and saturation from high to low.Increasing dry density is a very effective measure to reduce the compressibility of Yinchuan sandy soil,while increasing saturation has a better effect on improving the compactness of Yinchuan sandy soil.The compressibility model has good correlation and high significance,which is of practical significance to the prediction of compressibility of silty sand in Yinchuan Plain.