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基于Copula模型的降雨量与土壤饱和度的模拟研究 被引量:3
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作者 王沁 黄雁勇 +1 位作者 汤家法 向波 《灾害学》 CSCD 2010年第3期20-23,52,共5页
采用两步法,针对云南东川蒋家沟流域的降雨量与土壤饱和度,建立了边缘为皮尔逊Ⅲ型的Clayton Copula模型,分析了降雨量和土壤饱和度之间相关结构,以及两变量重现期,模拟了流域内土壤饱和度的变化情况。实例表明所构造的Clayton Copula... 采用两步法,针对云南东川蒋家沟流域的降雨量与土壤饱和度,建立了边缘为皮尔逊Ⅲ型的Clayton Copula模型,分析了降雨量和土壤饱和度之间相关结构,以及两变量重现期,模拟了流域内土壤饱和度的变化情况。实例表明所构造的Clayton Copula模型能比较好地模拟出流域内土壤饱和度在降雨情况下逐日变化情况,有助于进一步认识降水对土壤饱和度的作用过程,并为分析泥石流灾害的发生提供了一种新思路。 展开更多
关键词 泥石流 土壤饱和度 Clayton COPULA模型 二元联合分布 重现期 云南东川 蒋家沟流域
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土壤饱和度对柠条根与两类土界面摩擦特性的影响 被引量:3
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作者 苏禹 刘静 +3 位作者 李昊 张欣 李雪松 周丹丹 《内蒙古林业科技》 2017年第2期1-5,共5页
以内蒙古鄂尔多斯地区低液限粉土和粉土质砂及其人工柠条林为研究对象,通过重塑土直剪试验研究土壤含水率对柠条根与两类土界面摩擦特性的影响,为根-土相互作用机理提供理论和数据支持。结果显示:随着土壤饱和度由25%增至85%,低液限粉土... 以内蒙古鄂尔多斯地区低液限粉土和粉土质砂及其人工柠条林为研究对象,通过重塑土直剪试验研究土壤含水率对柠条根与两类土界面摩擦特性的影响,为根-土相互作用机理提供理论和数据支持。结果显示:随着土壤饱和度由25%增至85%,低液限粉土根-土界面的摩擦系数由0.438逐渐减小到0.35,粉土质砂则由0.517减至0.424;2种土壤质地根-土界面粘聚力呈先增大后减小的趋势,低液限粉土和粉土质砂根-土界面粘聚力分别在土壤饱和度为55%和40%时达到最大值,分别为4.986和3.056;土壤饱和度对根-土界面抗剪强度的影响随土壤类型的不同存在差异,在柠条根系主要分布层0.7 m和1.4 m内,2种土壤质地根-土界面抗剪强度随土壤饱和度增加呈现先增大后减小的趋势,且低液限粉土根-土界面抗剪强度高于粉土质砂,从固土效果角度,低液限粉土种植柠条的固土作用优于粉土质砂。 展开更多
关键词 土壤饱和度 根-土界面 摩擦特性 低液限粉土 粉土质砂 柠条
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陕北黄土区微地形土壤有效水饱和度 被引量:7
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作者 李增尧 赵兴凯 朱清科 《干旱地区农业研究》 CSCD 北大核心 2017年第4期88-94,共7页
为了明确不同微地形土壤有效水饱和度的特征以及与植被群落特征的关系,采用小波分析、回归分析和Mann-Kendall趋势检验等方法,分析了陕北黄土区阳向陡坡不同微地形0~60 cm土层深度的土壤有效水饱和度。结果表明:(1)在0~60 cm土层深度范... 为了明确不同微地形土壤有效水饱和度的特征以及与植被群落特征的关系,采用小波分析、回归分析和Mann-Kendall趋势检验等方法,分析了陕北黄土区阳向陡坡不同微地形0~60 cm土层深度的土壤有效水饱和度。结果表明:(1)在0~60 cm土层深度范围内,不同微地形土壤有效水饱和度顺序为塌陷<缓台<原状坡<切沟<浅沟<陡坎,其中切沟、塌陷和陡坎的土壤有效水饱和度呈现显著增加趋势,浅沟、缓台和原状坡的土壤有效水饱和度呈现下降趋势,但趋势不显著;(2)研究期间,不同微地形土壤有效水饱和度的变化周期不同,陡坎、塌陷和缓台的主周期相同,为22个月,浅沟、切沟和原状坡的主周期分别为23、21个月和28个月;(3)在不同微地形中,Margalef丰富度指数、Shannon-Wiener多样性指数、Simpson多样性指数和Alatalo均匀度指数均与土壤有效水饱和度呈正相关关系,其中Shannon-Wiener多样性指数和土壤有效水饱和度的相关性最高。 展开更多
关键词 陕北黄土区 阳向陡坡 微地形 土壤有效水饱和度
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施用粪肥和沼液对设施菜田土壤磷素累积与迁移的影响 被引量:24
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作者 王敏锋 严正娟 +4 位作者 陈硕 高杰云 李吉进 许俊香 陈清 《农业环境科学学报》 CAS CSCD 北大核心 2016年第7期1351-1359,共9页
针对有机蔬菜生产普遍施用粪肥和沼液的现状,利用多年田间定位试验,研究基施不同数量粪肥(CM1:30 t·hm^-2;CM2:60t·hm^-2;CM3:90 t·hm^-2)和追施相同量沼液对有机设施蔬菜产量、土壤磷素累积及其移动性的影响。结... 针对有机蔬菜生产普遍施用粪肥和沼液的现状,利用多年田间定位试验,研究基施不同数量粪肥(CM1:30 t·hm^-2;CM2:60t·hm^-2;CM3:90 t·hm^-2)和追施相同量沼液对有机设施蔬菜产量、土壤磷素累积及其移动性的影响。结果表明,2011—2014年不施粪肥单施沼液处理中(CK:0 t·hm^-2粪肥)累积磷素盈余量为290 kg P·hm^-2,0~30 cm土层土壤中Olsen-P和磷饱和度(DPS)均超过了磷素淋失的环境阈值。粪肥配施沼液处理显著增加了磷素盈余和磷素在土壤中的累积,试验期间2011—2014年累积磷素盈余量为不施粪肥单施沼液处理的6~22倍。随着粪肥施用量的增加,土壤全磷、Olsen-P、Ca Cl2-P、Mehlich3-P和DPS均迅速增加,当粪肥用量达到60 t·hm^-2时,显著增加了0~60 cm土层土壤全磷、Olsen-P、Ca Cl2-P、Mehlich3-P含量和DPS,大量粪肥施用并配施沼液处理使表层土壤DPS接近或达到100%。有机蔬菜生产中盲目大量施用粪肥和沼液,显著增加了土壤磷素累积和淋失风险,4年连续每茬90 t·hm^-2粪肥施用并配施沼液处理导致磷素在土壤剖面的迁移到达90 cm土层。与不施粪肥单施沼液处理相比,粪肥配施沼液显著提高了作物产量,但是较多量粪肥投入并没有继续增加作物产量,而显著增加了磷素淋失风险。因此,在有机蔬菜生产中推荐施用不超过30 t·hm^-2粪肥并配施沼液模式。 展开更多
关键词 粪肥 沼液 磷累积 磷迁移 土壤饱和度 环境风险
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黄土高原土壤干层评定指标的改进及分级标准 被引量:13
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作者 段建军 王小利 +2 位作者 张彩霞 高照良 李锐 《水土保持学报》 CSCD 北大核心 2007年第6期151-154,共4页
土壤干层是黄土高原普遍存在的特殊土壤水文现象,研究其现状、成因、防治、调控措施等对科学认识区域植被承载力、土地生产力以及低效林草改造和可持续植被建设等有重要理论与生产指导意义,而合理通用评判指标与分级标准是开展土壤干层... 土壤干层是黄土高原普遍存在的特殊土壤水文现象,研究其现状、成因、防治、调控措施等对科学认识区域植被承载力、土地生产力以及低效林草改造和可持续植被建设等有重要理论与生产指导意义,而合理通用评判指标与分级标准是开展土壤干层研究的基础。目前黄土高原土壤干层尚无统一评判指标与分级标准,给区域土壤干层研究带来困难。本文在已有研究成果的基础上,提出用土壤有效水饱和度/不饱和度作为土壤干层评判指标,并给出其分级标准。该评判指标计算简单,具通用性和可比性,可望成为土壤干层的通用评判指标。 展开更多
关键词 黄土高原 土壤干层 评判指标 土壤有效水饱和度
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土壤磷素淋溶预测指标研究 被引量:6
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作者 孙宏飞 吕家珑 +1 位作者 刘利花 张翠荣 《水土保持通报》 CSCD 北大核心 2006年第3期55-58,共4页
对西北农林科技大学农作一站长期肥料试验地0—20 cm耕层土壤研究表明:(1)易释放的各形态磷与全磷呈正相关关系;(2)土壤磷素的释放能力随pH值的增大而减小,不同处理的缓冲能力不同。释放能力的大小也与全磷的多少有关;(3)土壤全磷与PSD... 对西北农林科技大学农作一站长期肥料试验地0—20 cm耕层土壤研究表明:(1)易释放的各形态磷与全磷呈正相关关系;(2)土壤磷素的释放能力随pH值的增大而减小,不同处理的缓冲能力不同。释放能力的大小也与全磷的多少有关;(3)土壤全磷与PSD(土壤磷饱和度)有很好的正相关性。因此,基于以土壤饱和度为25%作为预测指标,把土壤全磷环境敏感指标(TP)为1.92 g/kg作为关中磷淋溶的环境敏感指标。 展开更多
关键词 土壤饱和度(PSD) 全磷(TP) 预测 释放
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基于大气降水的华北地区土壤湿度预测模型 被引量:8
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作者 王珊珊 韩丽娟 +1 位作者 崔恒建 杨华 《应用气象学报》 CSCD 北大核心 2011年第4期445-452,共8页
基于引入随机变量的机理性模型方法,利用华北地区2000—2008年气象台站观测数据,以大气降水为随机变量,并考虑其延迟效应,利用回归方法建立了预测时效为1旬的土壤相对湿度预测模型。利用预测率和干旱等级预报精度两个评价指标,结合2009... 基于引入随机变量的机理性模型方法,利用华北地区2000—2008年气象台站观测数据,以大气降水为随机变量,并考虑其延迟效应,利用回归方法建立了预测时效为1旬的土壤相对湿度预测模型。利用预测率和干旱等级预报精度两个评价指标,结合2009年土壤湿度实际观测数据,验证了预测模型预报率均在90%以上,绝大部分站点的干旱等级预报精度均在70%以上,得出该预测模型在华北地区应用的合理性,从而建立了一套客观、动态的土壤湿度预测方法,有利于及时掌握农田旱情程度和分布,主动采取防旱、抗旱应对措施。 展开更多
关键词 土壤湿度 土壤蓄水饱和度 降水延迟效应 非线性回归方程
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土壤环境影响评价中污染物浓度单位换算公式的推导及应用 被引量:1
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作者 刘玉兰 程莉蓉 《环境影响评价》 2021年第5期88-91,共4页
在土壤环境影响评价中,预测污染物浓度的计算结果与土壤环境质量相关标准中控制值的表征单位不同,给建设项目土壤环境影响评价工作带来不便。本文基于一定的假设条件,通过引入土壤干容重、土壤孔隙度及土壤水饱和度3个参数,推导出土壤... 在土壤环境影响评价中,预测污染物浓度的计算结果与土壤环境质量相关标准中控制值的表征单位不同,给建设项目土壤环境影响评价工作带来不便。本文基于一定的假设条件,通过引入土壤干容重、土壤孔隙度及土壤水饱和度3个参数,推导出土壤污染物质量浓度与水溶液中污染物体积浓度之间的换算公式,并选取某有色金属冶炼项目作为土壤环境影响评价案例,对公式进行了可操作性应用,进一步明确了公式的适用条件。 展开更多
关键词 环境影响评价 土壤污染物 单位换算 孔隙度 土壤干容重 土壤饱和度
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山洪灾害临界雨量研究综述 被引量:92
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作者 程卫帅 《水科学进展》 EI CAS CSCD 北大核心 2013年第6期901-908,共8页
临界雨量是一个关键的山洪灾害预警指标。按其技术原理将临界雨量推求方法划分为数据驱动的统计归纳法和基于灾变物理机制的水文水力学法分别进行评述,并介绍了临界雨量指标的两个拓展:动态临界雨量和暴雨临界曲线,综述了临界雨量不确... 临界雨量是一个关键的山洪灾害预警指标。按其技术原理将临界雨量推求方法划分为数据驱动的统计归纳法和基于灾变物理机制的水文水力学法分别进行评述,并介绍了临界雨量指标的两个拓展:动态临界雨量和暴雨临界曲线,综述了临界雨量不确定性分析的研究进展。通过综述发现:中国目前主要应用的是较简单的统计归纳法;临界雨量推求主要考虑前期降雨量(前期土壤饱和度)和时段累积降雨量两个因素的影响或仅后者一个;临界雨量指标难以反映山洪灾害的规模;考虑临界雨量不确定性有助于提高预警质量,但如何充分考虑其影响仍然是一个挑战。 展开更多
关键词 山洪灾害 临界雨量 前期土壤饱和度 降雨强度 累积降雨量
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基于HYDRUS-2D模型的玉米高出苗率地下滴灌开沟播种参数优选 被引量:15
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作者 莫彦 李光永 +3 位作者 蔡明坤 王丹 徐新涵 边新洋 《农业工程学报》 EI CAS CSCD 北大核心 2017年第17期105-112,共8页
开沟播种是一种可显著提高地下滴灌春玉米出苗率的新型播种方式,为了优化该技术模式,该文通过两年田间试验分析了地下滴灌玉米出苗率与灌水后种子处土壤有效饱和度(effective saturation)的关系,并基于HYDRUS-2D构建了地下滴灌开沟播种... 开沟播种是一种可显著提高地下滴灌春玉米出苗率的新型播种方式,为了优化该技术模式,该文通过两年田间试验分析了地下滴灌玉米出苗率与灌水后种子处土壤有效饱和度(effective saturation)的关系,并基于HYDRUS-2D构建了地下滴灌开沟播种土壤水分运动模型,以90%玉米出苗率为前提,研究了不同土质和土壤初始含水率条件下3个技术参数——开沟深度、滴灌带埋深和灌水量对种子处土壤有效饱和度的影响。结果表明:1)出苗率随土壤有效饱和度线性递增,土壤有效饱和度不小于0.77时,出苗率超过90%;2)地下滴灌开沟播种HYDRUS-2D模型模拟精度较高,模拟得到的土壤有效饱和度随开沟深度增大而增大,随滴灌带埋深增大而减小;3)满足土壤有效饱和度为0.77所需的出苗水灌水量随土壤黏粒含量、土壤初始含水率和开沟深度增大而减小,随滴灌带埋深增大而增大。当表层土壤初始含水率为40%田持~60%田持时,开沟深度每增加5 cm,砂壤土的出苗水灌水量减小15~20 mm,粉壤和粉黏土的出苗水灌水量减小6~18 mm;滴灌带埋深由30 cm增大到35 cm时,砂壤土的出苗水灌水量增大16~21 mm,粉壤和粉黏土的出苗水灌水量增大4~14 mm。不同埋深和开沟深度下,当表层土壤初始含水率由40%田持增大到60%田持时,砂壤土的出苗水灌水量减小9~14 mm,粉壤和粉黏土的出苗水灌水量减小9~19 mm;4)综合考虑土壤质地、玉米根系分布、机械作业、耗能、耕作深度和土壤水深层渗漏以及土壤初始含水率,玉米地下滴灌适宜的滴灌带埋深为30~35 cm,开沟深度为10~15 cm,灌水量范围为25~67 mm。农业生产者可以根据当地实际情况对以上3个技术参数进行合理配置。 展开更多
关键词 灌溉 质地 含水率 地下滴灌 开沟播种 HYDRUS-2D 土壤有效饱和度
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大中型水库不同等级暴雨的防汛调度研究
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作者 谷宏亮 曲凤垚 《中文科技期刊数据库(全文版)工程技术》 2021年第4期119-121,共3页
防汛决策是关系国计民生的大事,一场洪水调度过程中水库最高水位、下游最大泄量、调度期末水库水位等需要综合考虑。目前,气象部门3日内降雨精度已较高,对于水库而言,如果能在降雨开始时就计算出当前剩余防洪库容能够滞纳的降雨量,再对... 防汛决策是关系国计民生的大事,一场洪水调度过程中水库最高水位、下游最大泄量、调度期末水库水位等需要综合考虑。目前,气象部门3日内降雨精度已较高,对于水库而言,如果能在降雨开始时就计算出当前剩余防洪库容能够滞纳的降雨量,再对比气象部门发布的降雨预报,就可以尽早发布预警并适当调整水库调洪方式,从而最大限度的减少水库由于调度不及时而出现的溃坝或上下游淹没等问题。因此,就提出了大中型水库不同等级暴雨的防洪调度研究的问题,分析水库的抗暴雨能力,为防汛决策提供技术支撑,提高决策的科学性和时效性的参考。 展开更多
关键词 抗暴雨能力 前期影响雨量 土壤饱和度 降雨量级 水库防洪调度
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Salt-Water Transport in Unsaturated Soils Under Crop Planting: Dynamics and Numerical Simulation 被引量:7
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作者 XU Li-Gang YANG Jing-Song +1 位作者 ZHANG Qi LIU Guang-Ming 《Pedosphere》 SCIE CAS CSCD 2005年第5期634-640,共7页
A laboratory salt-water dynamics experiment using unsaturated soils in packed silt loam and clay soil columns withdifferent soil texture profiles and groundwater levels under crops were conducted to study the changes ... A laboratory salt-water dynamics experiment using unsaturated soils in packed silt loam and clay soil columns withdifferent soil texture profiles and groundwater levels under crops were conducted to study the changes of salt-waterdynamics induced by water uptake of crops and to propose the theoretical basis for the regulation and control of salt-water dynamics as well as to predict salinity levels. The HYDRUS 1D model was applied to simulate the one-dimensionalmovement of water and salt transport in the soil columns. The results showed that the salts mainly accumulated in theplow layer in the soil columns under crops. Soil water and salt both moved towards the plow layer due to soil waterabsorption by the crop root system. The salt contents in the column with lower groundwater were mostly greater thanthose with high groundwater. The water contents in the soil columns increased from top to the bottom due to plant rootwater uptake. The changes in groundwater level had little influence on water content of the root zone in the soil columnswith crop planting. Comparison between the simulated and the determined values showed that model simulation resultswere ideal, so it is practicable to do numerical simulation of soil salt and water transport by the HYDRUS 1D model.Furthermore, if the actual movement of salt and water in fields is to be described in detail, much work needs to be done.The most important thing is to refine the parameters and select precise boundary conditions. 展开更多
关键词 crop planting numerical simulation salt accumulation salt-water dynamics
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Relationship of Resistivity with Water Content and Fissures of Unsaturated Expansive Soils 被引量:7
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作者 CHEN Liang YIN Zong-ze ZHANG Pei 《Journal of China University of Mining and Technology》 EI 2007年第4期537-540,共4页
The development of fissures in expansive soils has a great effect on the stability of slope. Of the three phases of soils,the gas phase and solid phase are relatively insulated,so the average resistivity of soils can ... The development of fissures in expansive soils has a great effect on the stability of slope. Of the three phases of soils,the gas phase and solid phase are relatively insulated,so the average resistivity of soils can be calculated from the resistivity of the liquid phase. On this basis,the two-part model of resistivity changing with the water saturation of the expansive soil can be deduced. A 2-D resistance grid model is established based on simulating the resistance of ver-tically developed fissures. Variation in measured resistance of vertically developed fissures at different positions can be calculated from this model. Fissure development can be inversely determined from the variation in the measured resis-tance. Finally,the model is verified by an indoor resistivity test for remolded soil samples,indicating that the test result agrees well with that of the model established. 展开更多
关键词 unsaturated expansive soil RESISTIVITY fissure development degree of saturation resistivity structural model
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Sensitivity to Acidification of Forest Soils in Two Watersheds with Contrasting Hydrological Regimes in the Oil Sands Region of Alberta 被引量:1
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作者 Y. S. OK S. X. CHANG Y. S. FENG 《Pedosphere》 SCIE CAS CSCD 2007年第6期747-757,共11页
Input of large amounts of N and S compounds into forest ecosystems through atmospheric deposition is a significant risk for soil acidification in the oil sands region of Alberta.We evaluated the sensitivity of forest ... Input of large amounts of N and S compounds into forest ecosystems through atmospheric deposition is a significant risk for soil acidification in the oil sands region of Alberta.We evaluated the sensitivity of forest soils to acidification in two watersheds(Lake 287 and Lake 185)with contrasting hydrological regimes as a part of a larger project assessing the role of N and S cycling in soil acidification in forest ecosystems.Fifty six forest soil samples were collected from the two watersheds by horizon from 10 monitoring plots dominated by either jack pine(Pinus banksiana)or aspen(Populus tremuloides).Soils in the two watersheds were extremely to moderately acidic with pH(CaCl_2)ranging from 2.83 to 4.91.Soil acid-base chemistry variables such as pH,base saturation,Al saturation,and acid-buffering capacity measured using the acetic acid equilibrium procedure indicated that soils in Lake 287 were more acidified than those in Lake 185. Acid-buffering capacity decreased in the order of forest floor>subsurface mineral soil>surface mineral soil.The most dramatic differences in percent Ca and Al saturations between the two watersheds were found in the surface mineral soil horizon.Percent Ca and Al saturation in the surface mineral soil in Lake 287 were 15% and 70%,respectively;the percent Ca saturation value fell within a critical range proposed in the literature that indicates soil acidification.Our results suggest that the soils in the two watersheds have low acid buffering capacity and would be sensitive to increased acidic deposition in the region. 展开更多
关键词 acid-buffering capacity Al saturation base saturation pH soil acidification
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Relationship Between Soil Properties and Different Fractions of Soil Hg 被引量:2
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作者 WU HONGTAO YU GUIFEN +1 位作者 QING CHANGLE and CHEN TONGBIN Southwest Agricultural University, Chongqing 400716 (China) Institute of Geographic Sciences and Natural Resources, the Chinese Academy of Sciences, Beijing 100101 (China) Institute of Soil Science, th 《Pedosphere》 SCIE CAS CSCD 2001年第3期257-262,共6页
Correlation and path analysis methods were used to study the relationship between soil properties and the distribution of different soil Hg fractions with nine representative soils from Chongqing, China. Results showe... Correlation and path analysis methods were used to study the relationship between soil properties and the distribution of different soil Hg fractions with nine representative soils from Chongqing, China. Results showed that clay (< 2 m) could increase water-soluble Hg (r = 0.700*). Soil organic matter (OM) could enhance the increase of elemental Hg (r = 0.674*). The higher the base saturation percentage (BSP), the more the residual Hg (T = 0.684*). Organic Hg, the sum of acid-soluble organic Hg and alkali-soluble Hg, was positively affected by silt (2-20 μm) but negatively affected by pH, with the direct path coefficients amounting to 1.0487 and 0.5121, respectively. The positive effect of OM and negative effect of BSP on organic Hg were the most significant, with the direct path coefficients being 0.7614 and -0.8527, respectively. The indirect effect of clay (< 2 μm) via BSP (path coefficient = 0.4186) was the highest, showing that the real influencing factor in the effect of clay (< 2 μm) on acid-soluble organic Hg was BSP. Since the available Hg fraction, water-soluble Hg, was positively affected by soil clay content, and the quite immobile and not bioavailable residual Hg by soil BSP, suitable reduction of clay content and increase of BSP would be of much help to reduce the Hg availability and Hg activity in Hg-contaminated soils. 展开更多
关键词 different fractions soil Hg soil properties
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Effective stress in soils under different saturation conditions 被引量:1
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作者 徐浩峰 谢康和 《Journal of Central South University》 SCIE EI CAS 2011年第6期2137-2142,共6页
BISHOP’s effective stress or two state stress variables are unsatisfactory for unsaturated soils where one of fluid phases is discontinuous, so new expressions of effective stress should be founded. The approach for ... BISHOP’s effective stress or two state stress variables are unsatisfactory for unsaturated soils where one of fluid phases is discontinuous, so new expressions of effective stress should be founded. The approach for derivation was according to the principle of equilibrium of forces (i.e., the stress-sharing principle), and it was firstly validated by demonstrating TERZAGHI’s principle of effective stress. And then, the derivations were subdivided into four parts according to different pore air states: 1) air bubbles were spherical and suspended in pore water; 2) air bubbles were bound on soil skeleton; 3) air bubbles held almost the single section of pore; 4) air phase was continuous. The different formulae of effective stress were presented. Conclusions are drawn as follows: 1) For nearly-saturated soils, the "real" effective stress would be a little smaller than TERZAGHI’s effective stress; 2) For soils in which air phase is discontinuous in the form of bubbles, a new concept of pore air elastic pressure is put forward, and the total stress can be constituted by effective stress, pore water pressure and pore air elastic pressure; 3) For soils in which air phase is continuous, effective stress is equal to the value of the total stress plus suction; 4) Suction can be divided into two parts: one is the effect caused by additional pressure, and the other is the contract action by the "skin". 展开更多
关键词 unsaturated soils effective stress SUCTION surface tension occluded gas SATURATION
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Influence of water saturation on propagation of elastic waves in transversely isotropic nearly saturated soil 被引量:1
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作者 李保忠 蔡袁强 《Journal of Zhejiang University Science》 EI CSCD 2003年第6期694-701,共8页
Biot' s two-phase theory for fluid-saturated porous media was applied in a study carried out to investigate the influence of water saturation on propagation of elastic wave in transversely isotropic nearly saturat... Biot' s two-phase theory for fluid-saturated porous media was applied in a study carried out to investigate the influence of water saturation on propagation of elastic wave in transversely isotropic nearly saturated soil. The characteristic equations for wave propagation were derived and solved analytically. The results showed that there are four waves: the first and second quasi-longitudinal waves (QP1 and QP2), the quasitransverse wave (QSV) and the anti-plane transverse wave (SH) . Numerical results are given to illustrate theinfluence of saturation on the velocity, dispersion and attenuation of the four body waves. Some typical numerical results are discussed and plotted. The results can be meaningful for soil dynamics and earthquake engineering. 展开更多
关键词 SATURATION Transversely isotropic Nearly saturated DISPERSION ATTENUATION
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Batch washing of saturated hydrocarbons and polycyclic aromatic hydrocarbons from crude oil contaminated soils using bio-surfactant 被引量:3
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作者 张文 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第3期895-903,共9页
Desorption of total saturated fractions(i.e. SAT, defined for this study as the summation of the concentrations of the saturated hydrocarbon from n-C10 to n-C26) and polycyclic aromatic fractions(i.e. PAH, defined as ... Desorption of total saturated fractions(i.e. SAT, defined for this study as the summation of the concentrations of the saturated hydrocarbon from n-C10 to n-C26) and polycyclic aromatic fractions(i.e. PAH, defined as the summation of the concentrations of all polycyclic aromatic fractions including the 16 EPA priority PAH) in two types of soils subjected to the changes of p H and salinity and different bio-surfactant concentrations were investigated. In general, compared with the experiments without bio-surfactant addition, adding rhamnolipid to crude oil-water systems at concentrations above its critical micelle concentration(CMC) values benefits SAT and PAH desorption. The results indicate that the change of p H could have distinct effects on rhamnolipid performance concerning its own micelle structure and soil properties. For loam soil, the adsorption of non-aqueous phase liquid(NAPL) and rhamnolipid would be the principle limiting factors during the NAPL removal procedure. For sand soil, less amount of rhamnolipid is adsorbed onto soil. Thus, with the increase of salinity, the solubilization and desorption of rhamnolipid solution are more significant. In summary, the p H and salt sensitivity of the bio-surfactant will vary according to the specific structure of the surfactant characteristics and soil properties. 展开更多
关键词 bio-surfactant salinity desorption total saturated fractions(SAT) polycyclic aromatic fractions(PAH)
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Large-area Analysis of Soil Erosion and Landslides Induced by Rainfall: A Case of Unsaturated Shallow Deposits 被引量:1
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作者 CUOMO Sabatino DELLA SALA Maria 《Journal of Mountain Science》 SCIE CSCD 2015年第4期783-796,共14页
Unsaturated shallow soil deposits may be affected by either superficial soil erosion or shallow landslides in adjacent or overlapping source areas and in different seasons when a different soil suction exists.The trig... Unsaturated shallow soil deposits may be affected by either superficial soil erosion or shallow landslides in adjacent or overlapping source areas and in different seasons when a different soil suction exists.The triggering analysis of both these processes is a relevant issue for the hazard analysis while the literature mostly provides specific approaches for erosion or for landslides.The paper proposes a largearea analysis for a case study of Southern Italy,consisting of unsaturated shallow deposits of loose pyroclastic(air-fall) volcanic soils that have been repeatedly affected by erosion and landslides in special seasons.For a past catastrophic event, the simulated source areas of shallow landslides are smaller than those observed in the field while the simulated eroded areas with thickness greater than 5cm are comparable with the in-situ evidences, if the analysis takes into account high rainfall intensity and a spatially variable soil cover use.More in general, the results of the paper are consistent with the previous literature and also provide a methodological contribution about the application of distinct tools over large area.The added value is that the paper shows how the combination of distinct large-area analyses may help with understanding the dominant slope instability mechanisms.Only once this goal is fully achieved, can specific physically-based analyses be confidently performed at detailed scales and for smaller specific areas. 展开更多
关键词 Soil Erosion LANDSLIDE Soil Suction Slope instability mechanism Modelling
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Influence of Dry Density on Soil-Water Retention Curve of Unsaturated Soils and Its Mechanism Based on Mercury Intrusion Porosimetry
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作者 李博 陈宇龙 《Transactions of Tianjin University》 EI CAS 2016年第3期268-272,共5页
The soil-water retention curve(SWRC)can be used to evaluate the ability of unsaturated soils to attract water at various water contents and suctions. In this study, drying SWRCs for a kind of sandy soil were obtained ... The soil-water retention curve(SWRC)can be used to evaluate the ability of unsaturated soils to attract water at various water contents and suctions. In this study, drying SWRCs for a kind of sandy soil were obtained in the laboratory by using self-modified SWRC apparatus. In addition, the porosity and the pore size distribution of the samples were investigated by a mercury porosimetry test in order to analyze the effect of dry density. Results showed that the soil-water retention of the soil specimens was strongly dependent on the dry density. Under zero suction, soil specimens with a higher dry density exhibited lower initial volumetric water content. The higher the dry density of soil, the more slowly the volumetric water content decreased with the increase of suction. There was a general and consistent trend for a soil specimen to possess a larger air-entry value and residual suction, while smaller slope of SWRC when it had a higher density. This was probably attributed to the presence of smaller interconnected pores in the soil specimen with a higher dry density. The proportion of large diameter pores decreased in comparison to pores with small diameters in the soil tested. The measured total pore volume of the soil specimen, which had a larger dry density, was lower than that of the relatively loose specimens. 展开更多
关键词 soil-water retention curve dry density mercury intrusion porosimetry unsaturated soil
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