中文摘要：

残积土风化剧烈，研究其大变形下的工程特性很有必要。利用环剪仪的试验特点，可以研究土体在较大剪切位移下抗剪强度的变化规律。通过对残积土残余和峰值强度的环剪试验测定和对试验数据的整理与对比分析，得到了含水率与残余强度指标之间的关系，证明大变形下残积土具有浸水软化的特性；从应变阈值角度分析了残积土应变软化的性质，不同剪切位移下的残积土具有不同的抗剪强度，所研究的残积土达到峰值强度对应的应变介于0．02～0．06之间，而到达基本稳定的残余强度所需要的应变介于0．06～0．20区域内。研究还发现，矿物成分不同直接影响到残积土的残余强度，是残积土不均匀性的内部因素。

英文摘要：

It is imperative to study the engineering characteristics of residual soils which is weathered violently under large deformation. Making use of the test features of ring shear apparatus, the change law of shear strength of soils under large shear displacement can be studied. The experimental determination Of residual strength and peak strength indexes of residual soil is conducted by ring shear tests. Test data are analyzed through arrangement and comparison. The relationship between water content and residual strength proved the existence of property of watering softening under large deformation. The character of strain softening of residual soil is analyzed by strain threshold, that is, various shear strengths should be different with various shear displacements. Specifically, the peak strength corresponding to the range of strain is between 0.02 and 0.06 while the residual strength corresponding to the range of strain is between 0.06 and 0.20. Besides, the results also indicate that the residual strength of residual soil is directly affected by the difference of mineral composition, which is the internal cause of inhomogeneity of residual soils.