固化黄土的干湿循环特性研究

抗干湿循环能力是检验固化土耐久性能的重要指标，研究固化黄土的干湿循环特性具有较重要的意义。本文利用高分子材料SH固化剂对黄土进行固化改良，就固化黄土抗压和抗剪强度受干湿循环变化的影响开展室内模拟试验研究。试验结果表明：SH固化黄土试样经过干湿循环后，强度整体下降，但是仍远高于素黄土强度。随干湿循环次数的增大，抗压强度呈指数衰减，SH掺量增大，循环后的强度损失减小，质量损失率非常小，完整性良好。抗剪强度随干湿循环次数的增大而减小，干湿循环对SH固化黄土的黏聚力影响明显。不同掺量的SH固化黄土试件经3次干湿循环黏聚力下降，第4次循环后略有增大再下降，经多次循环下降平缓。经3～4次干湿循环的固化黄土试件的内摩擦角均有不同程度的降低，随后基本趋于稳定。由于增湿与脱湿过程中水分质量的变化，试样的质量和体积呈波状起伏变化。对掺量为10%的固化黄土应力应变关系分析得出其应变具有硬化特征。大于10%的SH固化黄土干湿循环之后仍然保持较高和较稳定的强度，能抵抗15次干湿循环，进一步说明了SH固化黄土的水稳性良好。SH固化剂在运用于黄土抗干湿循环方面具有明显的作用，因而具有较广阔的应用前景。

PROPERTY STUDY OF SOLIDIFIED LOESS UNDER WET-DRY CYCLES

The resistance of wet-dry cycles is an important durability index of solidified soil. It is important to explore the effect of environmental features, namely wet-dry cycles, on the performance and durability of loess solidification. In this paper, the solidified agent of SH is used in the loess solidification. By simulating the climate change of wet-dry cycles characteristics indoor, the effects of wet-dry cycles on compressive strength and shear strength of the solidified loess are analyzed. The test results show that: the strength of samples after wet-dry cycles is declined or weakened in overall. With the increase of number of cycles, the compressive strength values for samples exponential decline, but they are higher than the loess. SH content increases, the compressive strength losses reduce. The weight losses are very smaller, and the integrities are good. The parameters of shear strength decrease with SH content. The effects of wet-dry cycles on cohesion are obvious. During the beginning of three wet-dry cycles, the cohesions of the loess solidification by different contents of SH are decreased; after fourth cycles, the cohesions have a little increase, and then show a little decrease. With the increase of wet-dry cycles, they proceed to a relatively steady state. The internal friction angles of the solidified loess express a decreasing tendency, and maintain stability. Because of the change of water quality during the condensation-evaporation process, the weight and volumetric changes of specimens are flexuous. By analyzing the relationship between the stress and strain of the loess solidification by 10%SH content, it is concluded that the solidified loess has hardening characteristic. The loess solidification by more than 10%SH content is durable against 15 cycles for its higher and more steadying strength. Subsequent to that, it is good in water stability, and solidified agent of SH applied in loess of anti-wet-dry cycle has a prominent role. SH has a broad prospect in application.