In order to explore the disintegration characteristics of compacted loess, through the unsaturated soil disintegration instrument by independently developed,conduct the soaking disintegration experimental study on remolded soil unsaturated samples,obtained a series of experimental results:①The curves can be divided into the slow disintegration, rapid disintegration and stabilization of disintegration in three stages，the degree of compaction and water rate impact on rapidly disintegrating stage;②When the degree of compaction is certain,the disintegration rate decreased with the water contented increasing,the decreased amplitude is increasing with the moisture content increased to18%,the disintegration characteristics disappeared with the moisture content increased to 22%;③When the initial moisture content is certain, the disintegration rate decreased with the degree of compaction increasing, The time significantly prolonged when the disintegration completed. the decreased amplitude is increasing with the degree of compaction increased to 95%,the disintegration characteristics basically disappeared. Based on the relationship of degree of compaction and the moisture content to void ratio, the thesis establishes the model between the disintegration rate and the effective porosity ratio,the formula can be used to calculate the disintegration rate of compacted loess.The specific conclusions are:①When the critical moisture content increased to 22%,the disintegration characteristics disappeared;②When the critical degree of compaction increased to95%，the disintegration characteristics also disappeared.

Based on the understanding of diseases of building’s foundation and manmade slope caused by water capillary rise, this thesis carried out a large number of laboratory tests by selfdeveloped absorption permeameter for unsaturated soil, in order to explore the capillary transport law of unsaturated soil. The thesis obtains some valuable results and conclusions: The moisture content shows minishing trend as the seepage fronts increasing, and reflects the gravitational potential of normal relations with the capillary action; (2) the water seepage frontal Hω% relation curve has no obvious inflection point, but the initial water content has an certain influence on the capillary moisture content distribution, the moisture content uses the initial moisture content of 12.5%, 9.8%, 8.0% and5.3% for testing showed an increasing trend at 4 cm and 16 cm sections, and the moisture content at the same section increased with the initial moisture content increasing, this reflects the rule that the smaller the moisture content is, the greater the matric potential, the water absorption capacity becomes stronger. (3)The moisture content difference between 4 cm and 16 cm of the initial moisture content is 12.5%, 9.8%, 8.0% and 9.8% is 1.48 %, 1.5 %, 1.7 % and 2.2 %, indicating that the smaller the initial moisture content is, the difference at the vertical section is greater. Finally, based on the relationship of Hω% curve, the thesis establishes the grey correlation prediction model, and forecasts the maximum capillary height of Lishi loess is 182cm.

Vibration effect is a major inducing factor of loess slope hazards and the basis of revealing loess slope mechanism, which often changes loess structure and decreases loess strength. Based on the GDS Lab System, the dynamic triaxial test was performed by using equivalent sine wave under strain controlling. The results are described as follows: ① there is an obvious phenomenon of stress relaxation during the cyclic loading test on Malan loess, and the degree of stress relaxation decreases with the increase of confining pressure and dynamic strain. Under the low confining pressure, Malan loess reaches certain strain only by small dynamic stress within 2% strain ranges. Under high confining pressure, Malan loess will also reach certain strain value by small dynamic stress within 1% strain ranges. At the same time, with the increase of confining pressure, the peak value of dynamic stress increases gradually. ②The dynamic failure stress of Malan loess increases linearly with the increase of confining pressure. The correlation coefficient is 0.99 and the linear regression equation is бd = 0.001б3 + 0.019. ③On the basis of Molar Coulomb failure criterion, the index of dynamic strength was c =3.36kPa, φ=16°. In comparison with the static strength, the internal friction angle decreases significantly while the cohesion slightly.

Lishi loess is an important component of loess slope. To explore the structure and strength change characteristics of Lishi loess caused by shock (vibration) action, and to reveal the mechanism of loess slope catastrophe, the dynamic triaxial test was performed by using equivalent sine wave under strain controlling. The results show that:① There is an obvious stress relaxation phenomenon during the same cyclic loading test, the degree decreases with the increasing of dynamic strain and confining pressure. And the influence of dynamic strain variation on stress relaxation degree is less under high confining pressure than under low confining pressure;② Under a confining pressure of 40kPa, within 1% strain ranges, the needed dynamic stress to reach the specified strain is just 0.01kN, and the peak stress decreases with the augmentation of dynamic strain, when peak stress increases to 0.204kN, the sample is destructed; Under a confining pressure of 90kPa, soil radial particles are closely spaced, within 2% strain ranges also only a dynamic stress of 0.01kN is needed to reach the specified strain, and with the increase of dynamic strain, the samples are destructed when dynamic strain increases to 0.267kN. The dynamic failure stress of Lishi loess increases gradually with the increase of confining pressure, and the linear regression equation is бd=0.0011б3+0.1590, the correlation coefficient is 0.9944. ③According to Mohr-Coulomb failure criterion, the strength parameters of Lishi loess in somewhere of the north of shaanxi are C=30.33kPa，φ=14°. Under the dynamic shearing action, the dynamic effective strength parameters are obviously less than static effective strength parameters, this indicates that the soil consolidation effect reduced and the particles displaced and occluded each other.

Paleosol is an important factor affecting the stability of loess slope, and its mechanical properties, deformation and failure mechanism are still under in-depth exploration and research. Here based on the GDS Lab System, using equivalent sine wave progressively loading mode of strain controlling, in order to reveal the dynamic strength characteristics of Paleosol under the vibration effect. The result show that:① there is an obvious phenomenon of stress relaxation during the cyclic loading test on Paleosol; Paleosol is high-consolidated clay, when the given confining pressure less than the natural confining pressure, the degree of stress relaxation increased at first and then decreased,to the contrary first decreased and then increased.② under the 50kPa、80kPa、100kPa confining pressure, the dynamic failure stress of Paleosol is 0.176kN、0.2302kN、0.2555kN,the dynamic failure stress increases linearly with the increase of confining pressure. The correlation coefficient is 0.9009 and the linear regression equation is бd=0.001б3+0.0958.③ On the basis of Molar Coulomb failure criterion, We obtained the index of dynamic strength of Paleosol, which was C=25.63kPa and φ=14º, by Molar Circle. In comparison with the static strength, the internal friction angle and cohesion decreases significantly, show that the Paleosol have obvious characteristic of brittle.