Study On Evaluation Method Of Liquefaction Treatment Of Embankment Based On High Density Surface Wave Exploration

Soil compaction quality assessment of earth dams is significant in the world of geotechnical engineering.The anti-liquefaction safety of the reservoir dam is very important to the construction of earth dams.Much liquefaction prevention utilizes soil compaction.However,although anti-liquefaction methods may be comprehensive at present,previous research on the evaluation of compaction degree in large earth underground structures shows it is limited by spot samples that may need additional and extensive feedback during the lifespan of the earth dam.Therefore a reliable and accurate method using high density surface waves is proposed to supplement laboratory and other field tests to evaluate the compactness related to antiliquefaction methods and their effectiveness.Wangqingtuo Reservoir is an important part of China?s South-North Water Transfer Project in Tianjin and is used as an emergency reservoir for the vast population of North China.The surface of the reservoir area is distributed with a certain thickness silt of strong permeability,which is defined as liquefiable soil.Through field tests,laboratory test and especially the high density surface wave exploration,the liquefaction identification and liquefaction classification of Wangqingtuo reservoir area were carried out.Field tests included standard penetration tests and high density surface wave.Laboratory tests included conventional geotechnical tests,static triaxial tests,resonant column tests and dynamic triaxial tests.The distribution of shallow foundation structure was obtained by high density surface wave exploration.Due to the weak geological engineering conditions of the reservoir area and the location belonging to areas with basic earthquake intensity of degree 7,there is slight to medium liquefaction possibility of the dam foundation,when the reservoir is impounded.Therefore,liquefaction control measures need to be taken.From the points of improving soil compaction and initial stress of the liquefiable soil,four liquefaction control measures were put forward.They can be summarized as the surface excavation and backfilling,setting pressure platform before and after the dam,setting anti-seepage and strengthening drainage design,aiming to enhance anti-liquefaction capacity of the base by improving the liquefiable soil?s density,lower the infiltration line in the dam and increasing the overburden pressure of the base.During the construction process,the high density surface wave test and the laboratory test were carried out at different elevations.High density surface waves and borehole data from different points on the dam area are collected to provide an extensive geological survey.Survey measuring lines along the dam axis are used to construct shear wave velocity structure for the corresponding sections and used for comparison of soil dynamic soil properties.Consequently there is a comprehensive evaluation of the compaction of the dam foundation.The research puts forward the evaluation of foundation soil compaction using high density surface waves as an extensive non-destructive method to monitor the geological structure.