重庆紫色土抗侵蚀能力的粒组效应研究
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摘要
严重的水土流失导致不同粒径的土壤颗粒流失,改变了土壤的抗侵蚀能力。为研究粒组缺失对土壤抗侵蚀能力的影响,以重庆地区紫色土为对象,采用去掉某一粒组颗粒后的土壤作为试验用土,重塑制样进行控制围压与吸力的三轴试验。基于试验所得黏聚力c、内摩擦角φ等强度指标,分析土壤侵蚀机理。结果表明:(1)相对于无粒组缺失的试样,缺失较大粒径(0.25 mm以上)的试样内部颗粒间表面摩擦力和咬合力更大,缺失较小粒径(0.25 mm以下)的土壤颗粒间表面摩擦力和咬合力较低;(2)随着围压的增大,土壤抗侵蚀能力均得到显著提高,缺失较大粒径(0.25mm以上)的试样级配良好,压实性好,抗侵蚀能力提高的比例更大;缺失较小粒径(0.25 mm以下)的试样级配不良,不易被压实,抗侵蚀能力提高的比例相对较小;(3)颗粒级配不同的土体在固结剪切中会形成悬浮-密实结构、骨架-密实结构和骨架-孔隙结构,且抗侵蚀能力大小排序为骨架-密实结构>悬浮-密实结构>骨架-孔隙结构,且当黏聚力大于10 kPa时,影响土壤抗侵蚀能力的主要是土壤的内摩擦角;(4)通过灰色关联法分析发现,中值粒径d_(30)与黏聚力c、内摩擦角φ值关联度较大,有效粒径d_(10)与c、φ值关联度较小,并且不均匀系数Cu、曲率系数Cc、限定粒径d_(60)、d_(30)、d_(10)均对土壤抗侵蚀能力有显著影响。研究结果可以为重庆紫色土地区浅层滑坡和水土流失发生机理的研究提供试验数据和科学依据。
【Objective】Under a weather of plentiful rainfall, Chongqing is one of the most seriously eroded areas in China. The aggravating soil erosion causes depletion of soil particles of various sizes from the soil, weakening soil resistance to erosion, thus eventually leading to natural disasters, such as landslide and debris flow. So this paper aims mainly at exploring impacts of depletion of a certain fraction of soil particles on erosion resistance of the purple soil in Chongqing.【Method】 For this study, an indoor experiment was carried out on purple soil of loamy sands of which soil samples, after being fully dispersed,passed through a standard soil sieve to remove a certain fraction of soil particles and then got blended uniformly again to simulate the soil that had lost a certain fraction of soil particle as a result of soil erosion.In this way, soil samples different in absence of a fraction of soil particles were prepared, and then made the same in water content and density. and reshaped for triaxial consolidation shear tests through controlling suction of the matrix and changing confining pressure. Based on the parameters of cohesion c and internal friction angle φ obtained from the test, analysis of soil erosion mechanism was performed.【Result】Results show:(1) Compared with the sample of original soil, the samples with the fraction(0.25 mm or more) of soil particles removed were higher in surface friction and snap-in force between soil particles,while the samples with the fraction(below 0.25 mm) of soil particles removed were lower;(2) With rising confining pressure, soil erosion resistance of the sample significantly improved. The soil samples with the fraction(0.25 mm or more) of soil particles removed were good in graduation and in compactibility, as well,and hence were enhanced in erosion resistance by a larger margin, while the soil samples with the fraction(less than 0.25 mm) of soil particles removed were poor in graduation and in compactibility and enhanced in erosion resistance by a relatively limited margin;(3) In the consolidation shearing test, soil samples different in graduation formed a suspension-compaction structure, a skeleton-compaction structure, and a skeleton-pore structure, separately, with erosion resistance following an order of skeleton-compaction structure > suspension-compaction structure > skeleton-pore structure. In soil samples with cohesive force being higher than 10 kPa, the main factor affecting soil erosion resistance was internal friction angle of the soil; and(4) Grey correlation analysis shows that soil particles of median size, d_(30), was quite closely correlated with cohesion c and internal friction angle φ is large, while soil particles of effective size, d_(10),were not so. Besides, nonuniformity coefficient Cu, curvature coefficient Cc, limited particle size d_(60), d_(30),and d_(10) of a soil sample all had significant impacts on its erosion resistance.【Conclusion】All the findings in the study are expected to be able to serve as experimental data and scientific basis for future studies on mechanisms of shallow landslide and soil erosion in the purple soil area of Chongqing.
【Objective】Under a weather of plentiful rainfall, Chongqing is one of the most seriously eroded areas in China. The aggravating soil erosion causes depletion of soil particles of various sizes from the soil, weakening soil resistance to erosion, thus eventually leading to natural disasters, such as landslide and debris flow. So this paper aims mainly at exploring impacts of depletion of a certain fraction of soil particles on erosion resistance of the purple soil in Chongqing.【Method】 For this study, an indoor experiment was carried out on purple soil of loamy sands of which soil samples, after being fully dispersed,passed through a standard soil sieve to remove a certain fraction of soil particles and then got blended uniformly again to simulate the soil that had lost a certain fraction of soil particle as a result of soil erosion.In this way, soil samples different in absence of a fraction of soil particles were prepared, and then made the same in water content and density. and reshaped for triaxial consolidation shear tests through controlling suction of the matrix and changing confining pressure. Based on the parameters of cohesion c and internal friction angle φ obtained from the test, analysis of soil erosion mechanism was performed.【Result】Results show:(1) Compared with the sample of original soil, the samples with the fraction(0.25 mm or more) of soil particles removed were higher in surface friction and snap-in force between soil particles,while the samples with the fraction(below 0.25 mm) of soil particles removed were lower;(2) With rising confining pressure, soil erosion resistance of the sample significantly improved. The soil samples with the fraction(0.25 mm or more) of soil particles removed were good in graduation and in compactibility, as well,and hence were enhanced in erosion resistance by a larger margin, while the soil samples with the fraction(less than 0.25 mm) of soil particles removed were poor in graduation and in compactibility and enhanced in erosion resistance by a relatively limited margin;(3) In the consolidation shearing test, soil samples different in graduation formed a suspension-compaction structure, a skeleton-compaction structure, and a skeleton-pore structure, separately, with erosion resistance following an order of skeleton-compaction structure > suspension-compaction structure > skeleton-pore structure. In soil samples with cohesive force being higher than 10 kPa, the main factor affecting soil erosion resistance was internal friction angle of the soil; and(4) Grey correlation analysis shows that soil particles of median size, d_(30), was quite closely correlated with cohesion c and internal friction angle φ is large, while soil particles of effective size, d_(10),were not so. Besides, nonuniformity coefficient Cu, curvature coefficient Cc, limited particle size d_(60), d_(30),and d_(10) of a soil sample all had significant impacts on its erosion resistance.【Conclusion】All the findings in the study are expected to be able to serve as experimental data and scientific basis for future studies on mechanisms of shallow landslide and soil erosion in the purple soil area of Chongqing.
引文
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[8]葛莎,刘之葵,高伊航,等.重庆北碚区浸口滑坡形成机制和稳定性分析.广西大学学报(自然科学版),2015,40(4):934-942Ge S,Liu Z K,Gao Y H,et al.Formation mechanism and stability analysis of Jinkou landslide in Beibei District,Chongqing(In Chinese).Journal of Guangxi University(Natural Science Edition),2015,40(4):934-942
[9]李振林.汶川震区滑坡堆积体物质组成与堆积体休止角关系模拟研究.重庆:西南大学资源环境学院,2013Li Z L.The Wenchuan earthquake landslide accumulation substance pile repose angle of simulation on relations(In Chinese).Chongqing:College of Resources and Environment,Southwest University,2013
[10]王云琦,王玉杰,张洪江,等.重庆缙云山不同土地利用类型土壤结构对土壤抗剪性能的影响.农业工程学报,2006,22(3):40-45Wang Y Q,Wang Y J,Zhang H J,et al.Impacts of soil structure on shear-resistantance of soil under different land uses in Jinyun Mountain of Chongqing City(In Chinese).Transactions of the Chinese Society of Agricultural Engineering,2006,22(3):40-45
[11]钟小燕.预压固结时间与粒径级配对崩岗土体抗剪强度的影响.福州:福建农林大学资源与环境学院,2016Zhong X Y.Effects of preloading consolidation time and paricle size distribution on soil strength of granite collapsing hill(In Chinese).Fuzhou:College of Resources and Environment,Fujian Agriculture and Forestry University,2016
[12]Cruse R M,Larson W E.Effect of soil shear strength on soil detachment due to raindrop impact1.Journal Soil Science Society American,1977,41(4):777-781
[13]陈安强,张丹,熊东红,等.元谋干热河谷坡面表层土壤力学特性对其抗冲性的影响.农业工程学报,2012,28(5):108-113Chen A Q,Zhang D,Xiong D H,et al.Effects of mechanical properties of surface soil on soil anti-scourability in Yuanmou dry-hot valley(In Chinese).Transactions of the Chinese Society of Agricultural Engineering,2012,28(5):108-113
[14]谌芸,何丙辉,练彩霞,等.三峡库区陡坡根-土复合体抗冲性能.生态学报,2016,36(16):5173-5181Chen Y,He B H,Lian C X,et al.Root-soil system antiscourability on steep slopes in the Three Gorges Reservoir Area(In Chinese).Acta Ecologica Sinica,2016,36(16):5173-5181
[15]倪九派,高明,魏朝富,等.干湿循环条件下重庆地区三种土壤抗剪强度的动态变化.土壤学报,2013,50(6):1090-1101Ni J P,Gao M,Wei C F,et al.Dynamics of soil sheraing strength of three types of soils underwettingdrying alternationg in Chongqing Area(In Chinese).Acta Pedologica Sinica,2013,50(6):1090-1101
[16]汪时机,陈正汉,李贤,等.土体孔洞损伤结构演化及其力学特性的CT-三轴试验研究.农业工程学报,2012,28(7):150-154Wang S J,Chen Z H,Li X,et al.Pore-damage evolution and mechanical properties of remolded soil by CT-triaxial test(In Chinese).Transactions of the Chinese Society of Agricultural Engineering,2012,28(7):150-154
[17]张晓明,王玉杰,夏一平,等.重庆缙云山典型植被原状土抗剪强度的灰色关联度分析与评价.水土保持研究,2007,14(2):145-147Zhang X M,Wang Y J,Xia Y P,et al.Grey relational analysis and evaluation on anti-shear strength of the undisturbed soil of typical vegetations in Jinyun Mountain in Chongqing City(In Chinese).Research of Soil and Water Conservation,2007,14(2):145-147
[18]刘思峰,蔡华,杨英杰,等.灰色关联分析模型研究进展.系统工程理论与实践,2013,33(8):2041-2046Liu S F,Cai H,Yang Y J,et al.Advance in grey incidence analysis modelling(In Chinese).Systems Engineering-Theory&Practice,2013,33(8):2041-2046
[19]杨同,徐川,王宝学,等.岩土三轴试验中的粘聚力与内摩擦角.中国矿业,2007,16(12):104-107Yang T,Xu C,Wang B X,et al.The cohesive strength and the friction angle in rock-soil triaxial rests(In Chinese).China Mining Magazine,2007,16(12):104-107
[20]崔洁,江权,冯夏庭,等.岩石抗剪强度参数的理论概率分布形态研究.岩土力学,2015,36(5):1261-1274Cui J,Jiang Q,Feng X T,et al.Theoretical probability distribution of shear strength parameters for rock(In Chinese).Rock and Soil Mechanics,2015,36(5):1261-1274
[21]钟茫.非饱和紫色土抗剪强度影响因素研究.重庆:西南大学资源环境学院,2014Zhong M.Study on the influence factors of unsaturated purple soil shear strength(In Chinese).Chongqing:College of Resources and Environment,Southwest University,2014
[2]李月臣,刘春霞,赵纯勇,等.三峡库区重庆段水土流失的时空格局特征.地理学报,2008,63(5):475-486Li Y C,Liu C X,Zhao C Y,et al.Spatiotemporal features of soil and water loss in the Three Gorges Reservoir Area of Chongqing(In Chinese).Acta Geographica Sinica,2008,63(5):475-486
[3]苏正安,熊东红,张建辉,等.紫色土坡耕地土壤侵蚀及其防治措施研究进展.中国水土保持,2018(2):42-47Su Z A,Xiong D H,Zhang J H,et al.Research progress of soil erosion of purple soil slope farmland and its prevention and control measures(In Chinese).Soil and Water Conservation in China,2018(2):42-47
[4]温熙胜.三峡库区坡耕地土壤侵蚀研究.北京:北京林业大学水土保持学院,2007Wen X S.The study of soil erosion from sloping farmland in Three Gorges Reservoir area(In Chinese).Beijing:School of Soil and Water Conservation,Beijing Forestry University,2007
[5]程琴娟,蔡强国,李家永,表土结皮发育过程及其侵蚀响应研究进展.地理科学进展,2005,24(4):114-122Cheng Q J,Cai Q G,Li J Y.Summarization on study of soil surface crust or sealing and its effects on erosion(In Chinese).Progress in Geography,2005,24(4):114-122
[6]Barthès B,Roose E.Aggregate stability as an indicator of soil susceptibility to runoff and erosion;validation at several levels.Catena,2002,47(2):133-149
[7]陈晓燕,牛青霞,周继,等.人工模拟降雨条件下紫色土陡坡地土壤颗粒分布空间变异特征.水土保持学报,2010,24(5):163-168Chen X Y,Niu Q X,Zhou J,et al.Study on spatial variability characters of steep purple soil particles under rainfall simulation condition(In Chinese).Journal of Soil and Water Conservation,2010,24(5):163-168
[8]葛莎,刘之葵,高伊航,等.重庆北碚区浸口滑坡形成机制和稳定性分析.广西大学学报(自然科学版),2015,40(4):934-942Ge S,Liu Z K,Gao Y H,et al.Formation mechanism and stability analysis of Jinkou landslide in Beibei District,Chongqing(In Chinese).Journal of Guangxi University(Natural Science Edition),2015,40(4):934-942
[9]李振林.汶川震区滑坡堆积体物质组成与堆积体休止角关系模拟研究.重庆:西南大学资源环境学院,2013Li Z L.The Wenchuan earthquake landslide accumulation substance pile repose angle of simulation on relations(In Chinese).Chongqing:College of Resources and Environment,Southwest University,2013
[10]王云琦,王玉杰,张洪江,等.重庆缙云山不同土地利用类型土壤结构对土壤抗剪性能的影响.农业工程学报,2006,22(3):40-45Wang Y Q,Wang Y J,Zhang H J,et al.Impacts of soil structure on shear-resistantance of soil under different land uses in Jinyun Mountain of Chongqing City(In Chinese).Transactions of the Chinese Society of Agricultural Engineering,2006,22(3):40-45
[11]钟小燕.预压固结时间与粒径级配对崩岗土体抗剪强度的影响.福州:福建农林大学资源与环境学院,2016Zhong X Y.Effects of preloading consolidation time and paricle size distribution on soil strength of granite collapsing hill(In Chinese).Fuzhou:College of Resources and Environment,Fujian Agriculture and Forestry University,2016
[12]Cruse R M,Larson W E.Effect of soil shear strength on soil detachment due to raindrop impact1.Journal Soil Science Society American,1977,41(4):777-781
[13]陈安强,张丹,熊东红,等.元谋干热河谷坡面表层土壤力学特性对其抗冲性的影响.农业工程学报,2012,28(5):108-113Chen A Q,Zhang D,Xiong D H,et al.Effects of mechanical properties of surface soil on soil anti-scourability in Yuanmou dry-hot valley(In Chinese).Transactions of the Chinese Society of Agricultural Engineering,2012,28(5):108-113
[14]谌芸,何丙辉,练彩霞,等.三峡库区陡坡根-土复合体抗冲性能.生态学报,2016,36(16):5173-5181Chen Y,He B H,Lian C X,et al.Root-soil system antiscourability on steep slopes in the Three Gorges Reservoir Area(In Chinese).Acta Ecologica Sinica,2016,36(16):5173-5181
[15]倪九派,高明,魏朝富,等.干湿循环条件下重庆地区三种土壤抗剪强度的动态变化.土壤学报,2013,50(6):1090-1101Ni J P,Gao M,Wei C F,et al.Dynamics of soil sheraing strength of three types of soils underwettingdrying alternationg in Chongqing Area(In Chinese).Acta Pedologica Sinica,2013,50(6):1090-1101
[16]汪时机,陈正汉,李贤,等.土体孔洞损伤结构演化及其力学特性的CT-三轴试验研究.农业工程学报,2012,28(7):150-154Wang S J,Chen Z H,Li X,et al.Pore-damage evolution and mechanical properties of remolded soil by CT-triaxial test(In Chinese).Transactions of the Chinese Society of Agricultural Engineering,2012,28(7):150-154
[17]张晓明,王玉杰,夏一平,等.重庆缙云山典型植被原状土抗剪强度的灰色关联度分析与评价.水土保持研究,2007,14(2):145-147Zhang X M,Wang Y J,Xia Y P,et al.Grey relational analysis and evaluation on anti-shear strength of the undisturbed soil of typical vegetations in Jinyun Mountain in Chongqing City(In Chinese).Research of Soil and Water Conservation,2007,14(2):145-147
[18]刘思峰,蔡华,杨英杰,等.灰色关联分析模型研究进展.系统工程理论与实践,2013,33(8):2041-2046Liu S F,Cai H,Yang Y J,et al.Advance in grey incidence analysis modelling(In Chinese).Systems Engineering-Theory&Practice,2013,33(8):2041-2046
[19]杨同,徐川,王宝学,等.岩土三轴试验中的粘聚力与内摩擦角.中国矿业,2007,16(12):104-107Yang T,Xu C,Wang B X,et al.The cohesive strength and the friction angle in rock-soil triaxial rests(In Chinese).China Mining Magazine,2007,16(12):104-107
[20]崔洁,江权,冯夏庭,等.岩石抗剪强度参数的理论概率分布形态研究.岩土力学,2015,36(5):1261-1274Cui J,Jiang Q,Feng X T,et al.Theoretical probability distribution of shear strength parameters for rock(In Chinese).Rock and Soil Mechanics,2015,36(5):1261-1274
[21]钟茫.非饱和紫色土抗剪强度影响因素研究.重庆:西南大学资源环境学院,2014Zhong M.Study on the influence factors of unsaturated purple soil shear strength(In Chinese).Chongqing:College of Resources and Environment,Southwest University,2014