Research On Characteristics And Number Calculation Of Soil Lateral Deformation Induced By Vacuum-Surcharge Preloading

Preloading soft clayey deposit by combination of the vacuum pressure and surcharge load is a commonly utilized soft ground improvement method,because that method has the advantages of the vacuum preloading and surcharge load preloading.The rather larger lateral deformations induced by the geotechnical engineering activity may damage the buildings or underground pipelines around the reinforce area.So that controlling the deformation is not ignored in an urban environment.On the basis of the previous researches,researchs in this paper are concucted on three parts.In the first place,study on the calculation method of the soil lateral deformation around reinforce area considering the influencing factors.Secondly,research on the settlement-calculation in soft soil considering the lateral deformation.Finally,study on the laws of the soil lateral deformations influencing factors with FEM.Some conclusions have been obtained in this paper.1?Calculating of lateral deformation under the combination of vacuum and surcharge preloading:(1)Two parameters are defined which are given by the ratio of the soil lateral displacement around reinforce area to the central surface settlement(Rs)and the rate of the surcharge pressure to the representative undrained shear strength of the subsoil(Rp).Based on an existing field result,a simple equation for estimating the net lateral displacement under a combianation of vacuum pressure and surcharge load has been suggested.(2)A new method of settlement-calculation considering the lateral deformation is proposed.And by defining a correction factor of volume establish a formula of the soil settlement considering the lateral deformation under combined vacuum pressure and surcharge load.Comparison of the calculations and the field datas indicate that the calculated value is close to the actual settlement value.2 Laws of the soil lateral deformation under vacuum combined with surcharge preloading(1)Establish a model of project which was improved by combination of the vacuum pressure and surcharge load with finite element software.It shows that the model is feasible by comparison of the calculated results and simulated results.(2)Basing on the existing model,reaserch the laws of the ratio of loads?the load ratio?the initial undrained shear strength of the ground?the Poisson's ratio of soft and the vacuum pressure on the lateral deformation.The results indicate that the outward lateral deformation increases with the increasing of the ratio of loads,the load ratio and the Poisson's ratio of soft,decreases with the increasing of the vacuum pressure.Also show that the lateral deformation decreases with the increasing of the initial undrained shear strength of the ground.(3)The simulated rusults also show that the suface lateral deformation curves shapes around reinforce area are the same.They all present the "hook type".And the positions of the maximum lateral deformation are at the 1 to 3 meters away from the edge of reinforce area.