冻融作用对原状棕壤抗剪强度的影响  

Effect of Freeze-thaw Cycles on Shear Strength of Undisturbed Brown Soil

作　　者：朱龙祥 范昊明[1] 郭成久[1] 金丹[1] 谢立群[1] 马仁明[1] ZHU Longxiang;FAN Haoming;GUO Chengjiu;JIN Dan;XIE Liqun;MA Renming(College of Water Conservancy,Shenyang Agricultural University,Liaoning Province Key Laboratory of Soil Erosion Control and Ecological Restoration,Shenyang 110866)

机构地区：[1]沈阳农业大学水利学院,辽宁省水土流失防控与生态修复重点实验室,沈阳110866

出　　处：《水土保持学报》2021年第2期55-60,67,共7页Journal of Soil and Water Conservation

基　　金：国家重点研发计划项目(2016YFE0202900);国家自然科学基金项目(41601284)。

摘　　要：为揭示冻融循环作用对棕壤抗剪强度的影响,采集沈阳地区5 cm和25 cm 2个深度原状棕壤(分别为H 5和H 25)为研究对象,通过室内冻融循环模拟和土壤直剪试验,研究冻融循环次数和土壤含水率对土壤抗剪强度的影响。结果表明:(1)土样含水率越高,初次冻融作用的破坏效果越强,1次冻融循环后,含水率为25%的H 5和H 25土样黏聚力分别下降50.00%和25.87%;含水率35%的H 5和H 25土样黏聚力分别下降75.61%和50.77%。15次冻融循环后,含水率10%的H 5和H 25土样黏聚力分别增加74.36%和60.08%;含水率35%的H 5和H 25土样黏聚力分别增加14.63%和26.15%。但在2个不同含水率条件下,黏聚力的增大机制不同。(2)含水率为15%,20%,25%条件下,H 5和H 25土样内摩擦角在多次冻融循环中始终在一定范围内波动,说明这3个含水率下冻融作用对土壤内摩擦角影响具有不确定性。35%含水率的H 5和H 25土样内摩擦角受冻融作用的影响较小,分别在(18.57°±0.88°)和(12.86°±1.14°)变化。(3)平均抗剪强度主要受土壤含水率影响,随着含水率的增加呈指数函数减小。受黏粒含量影响,含水率低于25%时,H 25土样平均抗剪强度高于H 5土样;含水率高于25%时,H 25土样平均抗剪强度偏低。In order to reveal effects of freeze-thaw cycles on shear strength of brown soil,the undisturbed brown soil from 5 cm and 25 cm depths(H 5 and H 25,respectively)in Shenyang area were collected.The effects of freeze-thaw cycles and soil water contents on soil shear strength were analyzed through indoor freeze-thaw simulation and direct shear tests in laboratory.The results showed that:(1)The higher soil water content,the stronger damage effect of the first freeze-thaw cycle.After the first freeze-thaw cycle,soil cohesion of H 5 and H 25 samples with 25%soil water content decreased by 50.00%and 25.87%,respectively;and the soil cohesion with 35%soil water content decreased by 75.61%and 50.77%,respectively.After 15 freeze-thaw cycles,the cohesion of H 5 and H 25 samples with 10%soil water content increased by 74.36%and 60.08%,respectively;the cohesion of H 5 and H 25 samples with 35%soil water content increased by 14.63%and 26.15%,respectively.However,the mechanisms of cohesion increasing under two different soil water contents were different.(2)The internal friction angle of H 5 and H 25 samples with 15%,20%,and 25%soil water contents fluctuated during the multiple freeze-thaw cycles,indicating that the effects of freeze-thaw cycles on the internal friction angle were complicated and uncertain in the soil water contents.The internal friction of H 5 and H 25 samples with the soil water content of 35%were hardly affected by freeze-thaw cycles and varied between(18.57°±0.88°)and(12.86°±1.14°),respectively.(3)The average shear strength mainly decreased exponentially with the increasing of soil water contents.Clay content might play important role in average shear strength at different water contents.When the soil water contents were below 25%,the average shear strength of H 25 soil samples were higher than that of H 5;while soil water contents were above 25%,the average shear strength of H 25 were lower.

关 键 词：棕壤 冻融循环 抗剪强度 

分 类 号：S157.1[农业科学—土壤学]