管涌后缺级砂土的压缩固结特性试验研究

Experimental Research on Compression Consolidation Characteristics of Discontinuous Graded Sand after Piping

土体管涌对重要工程的危害众所周知,发生管涌后土体的承载力将直接影响上部建筑的安全性。故而研究管涌前后土体的压缩固结特性至关重要。选用标准试验砂与可溶性盐,利用相同级配的不同密实度砂进行不同管涌侵蚀程度下的缺级砂土压缩固结试验。结果表明,在相同的管涌侵蚀程度下砂土压缩性与固结系数都随管涌前初始密实度的增大而减小,其压缩模量则反之。随管涌侵蚀的扩大,土体压缩曲线变化并不规律,以30%的细粒流失量为转折点;而固结系数逐渐增大,且增大趋势明显。受管涌侵蚀越严重的砂土在同等附加应力作用下越容易发生沉降,压缩系数越大。利用函数拟合沉降量与时间关系曲线,分析得出土体沉降速率与初始密实度也有较大关联。

The damage of soil piping to important projects is well known.The bearing capacity of the soil after the piping will directly affect the safety of the upper building.Therefore,it is very important to study the compression consolidation characteristics of the soil before and after the piping.In this test,standard experimental sand and soluble salt are used,and different compactness sands of the same grade are used to carry out the compression consolidation test of the missing sand under different piping erosion degrees.The results show that under the same piping erosion degree,the compression and consolidation coefficient of sand decrease with the increase of the initial compactness before the piping,and the compression modulus is reversed.With the expansion of the piping erosion,the soil compression curve changes irregularly,with 30% of the fine particle loss as the turning point.The consolidation coefficient increases gradually,and the increase trend is obvious.The sand with more serious erosion by the piping is more likely to settle under the same additional stress,and the compression coefficient is larger.Using the function to fit the relationship between settlement and time,it is concluded that the soil settlement rate is also related to the initial compactness.