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.
The stability analysis and evaluation is the base of the landslide prevention, at the same time have improvement guidance to the landslide prediction. Divided the Chinese landslide stability analysis of research history into three stages:①experience analysis and evaluation stage;②half experience and semi theoretical analysis and evaluation stage;③theoretical development and the deeping stage. Described the research situation,trend and existing problems of the slide stability analysis and evaluation,get a clear conclusion,put forward my own understanding.
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.
In the landslide disaster control and high slope strengthening engineering, anti-slide pile is one of trusted engineering measures, but cognition in aspect of forced state on the anti-slide pile, the pile-soil mechanism etc, which should be strengthened. Therefore, monitoring objects with three cantilever anti-slide pile entities in the loess high slope somewhere, burying monitoring instruments such as earth pressure cells and steel bar meter, for as long as 18 months of monitoring. Through analysis of monitoring results, can draw the following conclusion:①The soil pressure distribution form before the anti-slide piles is parabola-shape as a whole, whatever above the slip surface or under the slip surface the soil pressure distribution form behind the anti-slide piles is almost triangle as a whole;②The anti-slide piles construction are completed, pile-soil interaction force and reinforced by stress reaches stability in about 16 months;③A maximum soil pressure before the anti-slide piles on the ground, the soil pressure behind the anti-slide piles near the potential sliding surface;④Before the anti-slide piles and behind the anti-slide piles, reinforced by stress from pile cap to pile bottom respectively is "compressive stress and tensile stress" and "compressive stress, tensile stress and compressive stress, tensile and compressive stress of zero before pile is tensile stress value maximize after pile.
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