Study On The Additional Stress Of Loess Slope Constructions' Foundations

Aiming at the loess slope foundation,focused on three factors,which are the slope angle,the water content of loess and the compaction degree of loess slope,we have carried out a series of indoor research experiments on the influence of the additional stress of the slope foundation.The test results show that:1)The classical theory of Boussinesq's solution is not applicable to the loess slope foundation's additional stress calculation,slope length and slope angle are factors that influence the effect of the slope additional stress in soil on the contrary.2)The slope angle has great influence on the distribution of the additional stress of the slope foundation.When the slope angle is less than 60 degrees,the measure to reduce the angles of the slope foundation can greatly increase the lateral restraint ability of soil,which can effectively achieve the purpose;when the slope angle is greater than 60 degrees,take the measure above is not only a heavy workload,but also can not increase the lateral restraint ability of the foundation effectively,we can take other measures,such as slope support,increase the foundation's slope distance.When it comes to the engineering practice,if the slope foundation does not meet the safety requirements,different measures should be taken to achieve our aim according to the slope angle,thus saving time and economic costs.3)The slope angle and the distance to the slope are all the factors which can lead to the additional stress' asymmetry under the slope foundation.In practical engineering,we should fully consider the asymmetry in the design and construction on the slope foundation,and measures should be taken only to reinforce or improve the slope side foundation effectively,which can reduce the unnecessary quantity of works while improve the bearing capacity of the foundation,so as to avoid the building foundation's uneven settlement and ensure the safety performance of the foundation,and bring the economic benefits for similar projects.4)The water content of loess has a great influence on the additional stress of loess slopefoundation.The moisture content is low,the linkage of the structure is strong,the original structure of the soil is not easy to be destroyed.When it suffers the additional stress,the good structure and structure index can help to lead the stress along the depth direction;With the increase of water content,water infiltration makes the shear strength of the loess decrease,and silty particles in the loess cohesion decrease,thus leading to the loess slope's deformation obviously.5)The compaction degree of loess slope has great influence on the additional stress of foundation.In a lower degree of loess compaction,the structure of the loess is loose and weak,the structure index is small.there are large pores between soil particles.Once suffered additional stress,the original structure will be destroyed,the soil will release a large part of the additional stress through deformation which was thought to be conducted erectly through soil particles.With the increasing numbers of tamping,the loess' density increases,the soil particles closely,the soil structure is strong,and structure index is increased,the pore between the soil particles is compressed,too.After sufferring the additional stress,the original structure's damage degree is reduced,the unconfined compressive strength increased.The additional stress will be well conducted down through the interaction between soil particles.