干湿循环过程对水泥改良土强度衰减机理的研究

水泥改良土是高速铁路路基工程中广泛使用的一种重要填料。本文通过固结不排水三轴剪切试验,在实验室内模拟环境条件的变化,研究了循环失水过程与水泥土强度变化之间的关系。结果表明,循环失水后水泥土的静强度都有一定程度的降低,特别是粉质粘土,经历一次失水饱和后其静强度降低了36%左右;环境变化的影响主要集中在前两次循环失水过程,两次之后强度基本稳定。本文还通过在改良土中置换一定比例的砂土来改善土料的颗粒级配,以降低循环失水对水泥土强度的影响。试验结果表明,这一措施对水泥土绝对强度的提高有一定程度的改善作用。

Test Study on Influence of Environmental Change to Strength Properties of Cement Improved soil

The cement improved soil is a kind of important fill material used widely in construction of railway subgrade.In the paper,authors simutate environmental change and get strength of cement improved soil through consolidation undrained triaxial shear test,and study relationships between them.Research results show that strength of cement improved soil dereased at some degrees when cement improved soil loses its water content,especially silty clay its strength creased about 36% through the first losing water content and saturation.The influence of environmental change concentrates mostly in the first two times and since then the strength will go stable.The authors also try to improve grain composition of soil by replacing cement soil with some sand to reduce influence of environmental change to strength of cement improved soil.Results show that this measure is useful to increase strength of cement improved soil.