干湿循环过程导致水泥改良土强度衰减机理的研究

水泥改良土是铁路路基工程中重要的填料。通过试验研究干湿循环过程对水泥改良粉质黏土与粉土强度衰减的影响程度,分析干湿循环过程导致水泥改良土强度衰减的机理,并进行了试验验证。结果表明,土料中黏粒团的干缩湿胀变形是引起干湿循环后改良土强度衰减的主要原因,适当降低改良土料中黏粒的相对含量可以有效提高干湿循环后改良土的强度。对于粉质黏土,采用掺砂方法,可使干湿循环后的水泥改良粉质黏土强度降低率减少50%。前2次干湿循环是导致改良土强度降低的主要过程,第3次干湿循环后,改良土的强度变化将趋于稳定。

Study on the Strength Degradation Mechanism of Cement-Soils Resulting from Dry-Wet Cycles

Cement-soil is an important filling material used in the railway subgrade engineering.The effect of dry-wet cycles on the strength degradation of the cement silty clay and the cement silt is studied by using tests.The strength degradation mechanism of cement-soils resulting from dry-wet cycles is analyzed based on test results and validated through tests.Results show that the dry shrinkage and wet dilatation deformation due to clay pockets is a main factor resulting in the strength degradation of cement-soils after dry-wet cycles.To decrease the relative contents of clay grains in silty clays can increase the strength of cement-soils after dry-wet cycles.For cement silty clay,it can decrease the degradation ratio of the strength to 50% by adding sand into the silty clay.The most important dry-wet processes resulting in the strength degradation are the first and the second cycles.The strength change of cement-soils tends to stability after the third dry-wet cycle.