干湿和冻融循环作用下黄土强度劣化特性试验研究

通过室内试验模拟土体季节性的干湿和冻融交替变化，采用直剪试验测试了原状黄土经干湿和冻融循环作用后的抗剪强度及抗剪强度参数的变化，并进行了直剪后试样的易溶盐总量测定.结果表明：干湿和冻融循环作用对原状黄土物理力学性质影响极大，是造成黄土边坡破坏的主要因素.随着干湿循环次数的增加，试样的抗剪强度逐渐减小，黏聚力逐渐减小，内摩擦角先增加，后逐渐趋于稳定，盐分迁移现象明显，土样下部易溶盐含量逐渐减少，上部易溶盐含量逐渐增加，并且试样的质量损失逐渐增加；随着冻融循环次数的增加，试样的抗剪强度逐渐减小，黏聚力逐渐增大最后趋于稳定，而内摩擦角和盐分迁移现象不明显.

Experimental study on the loess strength degradation characteristics under the action of dry-wet and freeze-thaw cycles

Laboratory experiments were used to simulate the soil seasonal dry-wet and freeze-thaw alternate chan-ges.Using direct shear test to measurement the change of the shear strength and parameters of undisturbed loess after dry-wet and freeze-thaw cycles,and determine the sample total soluble salts after direct shear test.The re-sults showed that:dry-wet and freeze-thaw cycles has a great influence on physical and mechanical properties of undisturbed loess,is the main factor of the loess slope failure.With the increase of dry-wet cycles,the shear strength of the sample decreases,the cohesive force is gradually reduced,internal friction angle first increases, then gradually stabilized,salt migration phenomenon obviously,the lower part of soil soluble salt content gradu-ally reduce,the upper soluble salt content gradually increases,and the mass loss of the sample increased.With the increase of freeze-thaw cycles,the shear strength of the sample decreases,the cohesive force is gradually in-creased,then gradually stabilized,but the internal friction angle and salt migration phenomenon not obviously.