《Journal of Geotechnical and Geoenvironmental Engineering》杂志刊登“粗粒宽级配土在低围压下的特性研究”

作者：H. F. Zhao; L. M. Zhang; and D. S. Chang

刊物：《Journal of Geotechnical and Geoenvironmental Engineering》，2013年1月，139卷第1期，35–48页

关键词：粗粒土；压缩性；滑坡；微观结构；抗剪强度；土体夯实；土壤组织

摘要：崩积土通常是粗粒和宽级配土，崩积土在降雨入渗过程中经常会发生浅层破坏。本文研究了浅层破坏中经常遇到的极低围压下粗粒、宽级配土的特性，该围压为5-25kPa。并采用孔隙比（0.62）相同，不同粗粒含量的一系列宽级配土进行了等向固结试验，三轴排水试验和三轴不排水试验。随着粗粒含量的增加，土壤的微结构会从由细粒控制结构变为粗粒控制结构，临界粗粒含量约为70%。由于团聚体间大孔隙的存在，含砾石粉砂压缩性在粗粒含量接近临界值时达到最大。即使在非常低的围压下，该土在不排水加载过程中仍表现出较强的压缩特性。这也解释了为什么崩积土在降雨入渗条件下大多发生浅层破坏。在相同的低围压下，粗粒含量比临界值偏低或偏高时，土壤表现出剪胀特性，并且其极限状态摩擦角也随着粗粒含量的增加而增大。

Behavior of Coarse Widely Graded Soils under Low Confining Pressures

Authors: H. F. Zhao; L. M. Zhang; and D. S. Chang

Journal: Journal of Geotechnical and Geoenvironmental Engineering, Volume 139, Issue 1 (January 2013), 35–48

Key words: Coarse-grained soil, compressibility, Landslides, Microstructures, Shear strength, Soil compaction, Soil fabric

Abstract: Colluvial soils are usually coarse and widely graded. Shallow-seated failures occur frequently in colluvial soil deposits during rainfall infiltration. This paper investigates the behavior of coarse, widely graded soils under very low confining pressures of 5–25 kPa encountered in shallow-seated failures. Isotropic consolidation tests, drained triaxial tests, and undrained triaxial tests were conducted on several widely graded soils with different coarse contents but with the same void ratio of 0.62. With increasing coarse content, the soil microstructure changes from a fines-controlled structure to a coarse-controlled structure after a critical coarse content of approximately 70%. Silty sand with gravel with a coarse content close to the critical value exhibits the highest compressibility because of the presence of large inter aggregate pores. Even under very low confining pressures, such soil still shows strong contractive behavior during drained loading, and generates large positive pore-water pressures during undrained loading. This explains why shallow-seated failures occur frequently in colluvial soil deposits caused by rainfall infiltration. Soils with lower or higher coarse contents than the critical value may show dilative behavior under the same low confining pressures. The critical state friction angle increases with the coarse content.

原文链接：http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000755