A Study Of The Characteristics Of Liqueifable Soils And Anti-Liquefaction Measurements In The Zhengdong New District, Henan

Purpose: Effected by periodic dynamic loads as earthquake, soils with lower viscosity such assaturated sand soil, silty soil or sandy silt are easy to be liquefied, which will lead to the failure offoundations where structures or other facilities may be damaged. With the dynamic loads ofearthquake fixed, main factors influencing the liquefaction of saturated soils are its granules,compaction, depth of water level underground and thickness of covered non-liquefied soils. Inorder to reduce the loss caused by liquefaction-induced damage, it is very necessary to researchefficient anti-liquefaction measures. In the paper, Zhengdong New District is taken as subjectinvestigated, on the basis of deep discussion on the liquefaction mechanism and judging methodsfor liquefaction, the paper, which takes field drilling, in situ test and indoor test as main measures,conducts a series of investigation on the liquefiable soils in the investigated area, and determinesphysical mechanical characteristics of the liquefiable soils. Meanwhile, it describes physicalgeography, geologic conditions, hydrogeology and seismological engineering geology in the area,and makes judgment and appraisal on the possibility of liquefaction of low-viscosity soils and theliquefaction level in the area. It summarizes physical mechanical characteristics of the liquefiablesoils and investigates the characteristics of horizontal distribution and depth distribution. Itanalyzes and appraises the possibility of seismic settlement of liquefiable soils and gives overallappraisal on the characteristics of liquefiable soils in the area.Contents and Methods:In order to take efficient anti-liquefaction measures, the paper conducts studies and analysisupon the anti-liquefaction mechanism and treatment effect of foundation treatment methods suchas dynamic consolidation, sand-gravel pile, and pile foundation, etc, and advances the feasibilityof cement mixing pile to resist liquefaction, and makes discussions in the anti-liquefactionmechanism. Through the analogy analysis of specific construction cases, it indicates the deficiencyof pile foundation for anti-liquefaction, and optimizes and combines the anti-liquefactionmeasures of foundation soils, and lodges new ideas and patterns of damping isolation belt to be setaround buildings.Main Views and Conclusion: under the earthquake intensity of level 7, there are liquefiable soilsunder slight-medium liquefaction level in the investigated area, and the setting depth of liquefiablesoil shall be not more than 16m, which belongs to liquefiable and possibly liquefiable fields, thefoundation of structures shall be treated according to the requirements of anti-liquefactionmeasures. Except general anti-liquefaction measures as dynamic consolidation, sand-gravel pile,the cement-mixing pile is feasible as well, because the fines contents in cement change theformation of soil particles, and the contents of cosmid can be increased by about 3%. In theabove-mentioned foundation process method, the bearing capacity of foundation will generally notexceed 200kPa. The anti-liquefaction measures shall be optimized and combined as to reach anideal liquefaction effect. In addition, it lodges new ideas and patterns of damping isolationfoundation for anti-liquefaction, model tests indicate that the method works well to improve theanti-liquefaction of buildings, and the cycle index of stresses needed for liquefaction and damagesof buildings are increased by 40-50% respectively, in addition, the paper gives suggestions for thenext procedures.