A E-p Curve Model For Soil Compression Process And Its Engineering Applications

The simulation method for compression process of soils, namely e-p curve model,is an important basis for calculation of foundation settlement. The Layer-wiseSummation analysis as the extensive application of foundation settlement calculationmethod is estabilished on the base of the soil compression characteristics and e-pcurve model. e-p compression curve of soil is get in completely lateral restraintconsolidation test conditions, it is difficult to adopt the analytical method. When toget corresponding void ratio of corresponding pressure based on compression testcurve of soil will be caused by human error and not facilitate compuer processing. Onthe other hand, sometimes the e-p test curve can not get in actual project, which causethe Layer-wise Summation analysis unable to use. Then some scholars have proposeda variety of e-p curve model of soil compression, but there are still somen deficiencies.The model parameters of these methods must be obtained based on the measuredcurves using fitting methods, when the e-p test curve can not get these method is stilldifficult to implement, and the model parameters is lack of clear physical meaning.Stress history of foundation soil effect the compression process very clealy, but theexisting considerable part of the e-p curve model does not consider the issue.Therefore, if we can use conventional compression indicators to express the e-p curvemodel for foundation soil’s compression process simulation, it obviously hasimportant theoretical and practical significance to pefect the foundation settlementanalysis methods.Firstly, based on the initial compression deformation mechanism and the e-pcurve characteristics of soils, the hyperbolic model of the relationship betweencompression stress and strain of soils is introduced, and a e-p curve analysis modelabout the simulation of initial compression deformation process of soils and itsparameters determination method are established from the relationship between strainand void ratio of soils in completely lateral restraint consolidation test conditions.The basic form of the model function is relatively simple, only contains the initialcompression modulus, compression coefficient and initial void ratio threeconventional test parameters. Model parameters do not need to be determined byfitting method based on the e-p test curve of siol compression process. Afterwards, Considering the essential differences between initial compressionand recompression process in pre-consolidation stress is that their initial void ratioand initial compression modulus are different, and based on deep discussion for thecomputation method of the unrecoverable strain that is produced when the initialcompression soil at pre-consolidation stress is competely unloaded，a determinationtechnique of the parameters such initial void ratio as well as initial compressionmodulus about the recompression soils is developed, thus, a e-p curve analysis modelconsidering the impact of stress history is set up, which can simulate the deformationprocess of the recompression soils. The e-p curve analysis models aboutrecompression soils only include three routine test parameters as the same with thee-p curve analysis models about initial compression.Finally, the e-p curve analysis models about initial compression andrecompression soils is applied in the Layer-wise Summation analysis, and it is used toanalysis the foundation settlement of an ordinary residential floors in Beidaihe area ofQinhuangdao. The theoretical and the measured values is relatively close, it is shownthat the models in this paper are reasonable and feasible.