压实粉土非线性应力-应变关系的试验研究

对京九线路基粉土用GDS三轴仪进行固结不排水剪试验,研究不同围压、含水量、压实度下压实粉土样的应力-应变关系。结果表明:压实粉土在低围压下为应变软化,高围压下为应变硬化,存在一个屈服应力;含水量和压实度对粉土强度和应力-应变关系影响显著,随着含水量的减小、压实度的增大,压实粉土样强度增大,应力-应变曲线上升。对围压小于屈服应力的应变软化曲线,用常规的土的软化关系式进行拟和;对围压大于屈服应力的应变硬化曲线,用邓肯-张模型进行拟和;这二者的结合能描述压实粉土的应力-应变关系曲线,效果良好。

TRIAXIAL TEST RESULTS FOR NONLINEAR STRESS-STRAIN RELATIONSHIP OF COMPACTED SILT

Based on the CU triaxial tests on compacted silt from the Beijing to Kowloon railway subgrade,the stress-strain relationship analysis is made on the silt under different cell pressures,water contents and degrees of compaction.It is found that the compacted silt exhibits a work hardening character under high cell pressure,exhibits a work softening character under low cell pressure,and exists a yield stress.The effects of water content and compaction on soil strength and stress-strain curves are distinct.The common softening formulation of soils is adopted to describe the softening curves under low cell pressure which is less than the yield stress.For the hardening curves,the Duncan-Chang model is used.Combining the stimulation methods mentioned above,the stress-strain relationship of the compacted silt is depicted well.