引用本文:章 智,陈 洁,林金石,蒋芳市,葛宏力,连彬彬,黎造宇,黄炎和.含水率对安溪县花岗岩崩岗土体胀缩特性的影响[J].土壤学报,2020,57(3):600-609. DOI:10.11766/trxb201903230072
ZHANG Zhi,CHEN Jie,LIN Jinshi,JIANG Fangshi,GE Hongli,LIAN Binbin,LI Zaoyu,HUANG Yanhe.Effect of Water Content on Swell-Shrink Characteristics of Collapsed Granite Soil in Anxi County[J].Acta Pedologica Sinica,2020,57(3):600-609. DOI:10.11766/trxb201903230072
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含水率对安溪县花岗岩崩岗土体胀缩特性的影响
章 智,陈 洁,林金石,蒋芳市,葛宏力,连彬彬,黎造宇,黄炎和
福建农林大学资源与环境学院
摘要:
崩壁土壤水分变化是导致崩岗发生和发展的主要因素之一。降雨可以导致崩岗崩壁失稳发生崩塌,降雨过程中土体在不同含水率下的胀缩特性是决定崩壁失稳的关键因素之一。本研究以安溪县典型崩岗崩壁土体为对象,通过室内无荷膨胀率和线性收缩率试验,研究不同梯度含水率对崩壁不同土层胀缩特性的影响。结果表明:不同土层的无荷膨胀率均随初始含水率增大而减小,线性收缩率则相反。初始含水率与崩壁不同层次土壤无荷膨胀率之间存在着明显的指数递减关系,各土层拟合所得到的回归方程均可表达为:δe=ae( /b) +cR2>0.96;初始含水率与崩壁不同层次土壤线性收缩率之间则存在着明显的指数递增关系,各土层拟合所得到的回归方程均可表达为:δsl =ae(ω /b) +cR2>0.96。对于同一土层,膨胀的变化幅度大于收缩的变化幅度。比较不同土层的膨胀和收缩变化幅度发现,红土层变化幅度最大,分别较砂土层高2.58%和3.33%,较碎屑层高3.61%和4.67%。这种不可逆的干湿胀缩现象可能是造成土体产生裂隙进而引起崩壁坍塌的原因,这对于认识崩壁失稳崩塌原因和崩岗发生机理具有重要意义。
关键词:  花岗岩崩岗  初始含水率  无荷膨胀率  线性收缩率
基金项目:国家自然科学基金项目(41571272)
Effect of Water Content on Swell-Shrink Characteristics of Collapsed Granite Soil in Anxi County
ZHANG Zhi, CHEN Jie, LIN Jinshi, JIANG Fangshi, GE Hongli, LIAN Binbin, LI Zaoyu, HUANG Yanhe
College of Resources and Environment, Fujian Agriculture and Forestry University
Abstract:
【Objective】 Change in soil moisture of a collapsed wall is one of the main factors leading to occurrence and development of collapse therein. Rainfall can cause unstability and eventually collapse of the wall. During this process, the swell-shrink characteristics of the solum as affected by soil water content play an important role in mound collapsing. In the past, studies paid most attention to effect of water content on the swelling-shrinkage characteristics only in a single soil layer. 【Method】 With the collapsing mounds or walls typical of Anxi County of Fujian as object, effect of water content on the swell-shrink characteristics of a solum or a mound relative to soil layer was studied via indoor tests on no-loading expansion rate and linear shrinkage rate. 【Result】 Results show that no-loading expansion rate of the soil, regardless of layer, decreased with increasing initial water content, while linear shrinkage rate was in a reverse trend. Initial water content exhibited an obvious exponential decreasing relationship with soil unloading expansion rate in all soil layers and the relationship could be fitted with a regression equation of δe=ae( /b) +cwith R2>0.96. But initial water content did have a significant exponential increasing relationship with linear shrinkage rate of the soil, regardless of soil layer, and the relationship could be fitted with a regression equation of δsl =ae(ω /b) +c with R2>0.96 in all soil layers. So initial water content had a good exponential relationship with no-loading expansion rate and linear shrinkage rate. In the same soil layer, the expansion varied more greatly than the shrinkage did in extent. Comparison between soil layers in extent of the variation of expansion and shrinkage rates shows that the red soil layer was 2.58% and 3.33% higher than the sandy soil layer, and 3.61% and 4.67% higher than the detritus soil layer, respectively. 【Conclusion】 These irreversible phenomena of swelling-shrinking might be the main cause to form cracks in the solum, which then eventually lead to soil collapse. This work is of certain important significance to understanding the causes and mechanism of collapsing of mounds.
Key words:  Granite collapse  Initial water content  No-loading expansion rate  Linear shrinkage rate