引用本文:喜银巧,赵 英,李生宇.三种土壤改良剂对风沙土抗剪强度的影响[J].土壤学报,2018,55(6):1401-1410.
XI Yinqiao,ZHAO Ying,LI Shengyu.Effects of Three Kinds of Soil Amendments on Shear Strength of Aeolian Soil[J].Acta Pedologica Sinica,2018,55(6):1401-1410
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三种土壤改良剂对风沙土抗剪强度的影响
喜银巧,赵英,李生宇
新疆生态与地理研究所,新疆生态与地理研究所,新疆生态与地理研究所
摘要:
为探明不同土壤改良剂对风沙土力学特征的影响,采用羧甲基纤维素钠、磷石膏及生物炭三种改良剂添加到风沙土中,进行棉花盆栽实验,通过直剪法测定改良前后的土壤内聚力和内摩擦角,分析了两种土壤含水量条件下不同土壤改良剂添加风沙土的抗剪强度。结果表明:(1)无论含水量高低,经三种改良处理的风沙土内聚力均显著大于对照,三者大小关系呈羧甲基纤维素钠>磷石膏>生物炭,表明施用羧甲基纤维素钠对风沙土抗剪强度改良效果最佳;与对照相比,改良剂处理对内摩擦角影响未达到显著程度(P>0.05)。(2)随土壤改良剂添加量的增加,土壤内聚力亦增大,且拟合效果较好,但内摩擦角变化不明显。(3)在同一添加量情况下,低水处理的风沙土内聚力和内摩擦角均大于高水处理,但处理间差异不显著(P>0.05)。(4)土壤改良剂及含水量主要通过增大内聚力来提高土壤抗剪强度,但各因素间交互作用均对内聚力无显著影响。
关键词:  风沙土  土壤改良剂  土力学  抗剪强度
DOI:10.11766/trxb201802120564
分类号:
基金项目:国家千人计划新疆项目(Y472241001)
Effects of Three Kinds of Soil Amendments on Shear Strength of Aeolian Soil
xi yinqiao,zhaoying and lishengyu
Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences,Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences,Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences
Abstract:
【Objective】Application of soil amendments to assist desert governance has recently been considered as a promising strategy to improve sand fixing efficiency. However, researches in the past were focused mainly on effects of soil amendments on physicochemical and biological properties of the soil, while this study aimed to reveal those on shear strength of aeolian soils varying in soil water content, in an attempt to provide certain theoretical references for fixing aeolian sands, preventing wind erosion and restoring ecosystems in desert areas. 【Method】In order to explore factors affecting soil mechanics of aeolian soil, soil samples were collected at the edge of the Kumtag Desert for a pot experiment, designed to investigate changes in soil cohesion and internal friction angle via direct shear test. Three kinds of soil amendments were applied, separately into the pots, at set rates, that is, 0.5, 2.0 and 3.5 g•kg-1 for carboxymethylcellulose sodium (CMC); 5, 15 and 25 g•kg-1 for phosphogypsum (PG); and 15, 30 and 45 g•kg-1 for biochar (BC). For each group of treatments, two subgroups different in water content, i.e; 10% and 20%, were also designed. Cotton was planted in each pot and managed in line with the common practice for the crop in the field . At the end of the growth season, soil samples were collected from each pot dried for analysis of cohesion and internal friction angle. Fast shear tests were carried out with a EDJ-1 type direct shear-meter. Four vertical pressures,100, 200, 300 and 400 kPa were applied in the shearing tests, separately. 【Result】Results showed:(1)being the same in soil moisture content, the soil cohesions in the three amended groups were greater than those in the CK group in coherence. Compared with that in CK, cohesion increased by 156.15%~246.18% in Treatments CMC, by 81.06%~229.3% in Treatments PG, and by 71.91%~145.87% in Treatments BC in the subgroup of low water content, and by 126.3%~231.8%, 75.52%~209.9% and 57.79%~124.8%, respectively, in the subgroup of high water content. However, application of soil amendment did not have much effect on soil internal friction angle in aeolian soil.(2)with increasing application rate of soil amendments, soil cohesion significantly increased, showing a positive relationship and good regression between cohesion and soil amendment application rate. (3) being the same in amendment application rate, the soils low in soil water content were higher than their corresponding ones high in soil water content in both cohesion and internal friction angle, but the difference was not significant(P>0.05), and the former was 21.02%, 24.69% and 11.57% higher in Treatments CMC, 10.3%, 19.05% and 13.59% higher in Treatments PG and 16.49%, 9.48% and 16.93% higher in Treatments BC. 【Conclusion】In summary, application of soil amendments can significantly improve soil cohesion, but does not have much effect on soil internal friction angle. In terms of soil coherence enhancing efficiency, the three kinds of soil amendments exhibit an order of carboxymethylcellulose sodium> phosphogypsum> biochar. All the findings in this study demonstrate that low soil water content is more conducive to improvement of shear strength of aeolian soil, by enhancing soil cohesion, together with application of soil amendments, thus stabilizing aeolian soil and improving ecological environment of the desert area. Among the three kinds of soil amendments, CMC is the most effective one.
Key words:  Aeolian soil  Soil amendment  Soil mechanics  Shear strength