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1.
通过对南京地区大量粘土和粉质粘土样品热导率值的测试,分析了土体热导率与其含水量、孔隙比的相关关系。对影响土体导热值的因素作了详细分析,提出了根据土体含水量、孔隙比值计算土体热导率的经验计算公式。 相似文献
2.
The hydro-mechanical behaviour of a clay-based buffer material for nuclear waste disposal has been investigated in a laboratory program. In this program, the main focus was on the influence of confinement on water uptake and swelling pressure during suction decrease. The laboratory program and some of the results are presented by Dueck [Dueck, A., 2006. Laboratory results from hydro-mechanical tests on a water unsaturated bentonite. submitted for publication.]. The results from the laboratory tests were used to find a relationship between water content, void ratio, swelling pressure and suction. Two equations for swelling pressure represent the outline of the model. In the first equation, the swelling pressure developed during water uptake is normalised by a pressure corresponding to the swelling pressure at saturation. This is done in order to be independent of void ratio. A relationship between the normalised swelling pressure and the degree of saturation is suggested. The second equation describes a relationship between the swelling pressure, the water content and the actual suction (or relative humidity). The equation is based on a thermodynamic relationship and includes the retention curve (i.e. water content vs. suction under free swelling conditions). The model can be used for a state where two of the four variables; water content, void ratio, swelling pressure and suction are known and can thus be useful to evaluate field measurements and model late stages of the wetting process. An example of an application is given. The equations are mainly based on results from tests with increasing degrees of saturation under constant void ratio but are also suggested for use with increasing void ratio. 相似文献
3.
在收集已有资料的基础上,通过野外调查和土工样品采集测试分析,结果表明：桂林红土主要由石英砂粒及高岭石、伊利石、绿泥石等次生粘土矿物组成,其体积分数为40%~75%;铁铝氧化物高度富集,一般w(Al 2O 3)为15.3%~25.9%,w(Fe 2O 3)为6.4%~11.2%。土中粘粒体积分数大都在50%以上;土的天然含水量、液限含水量、孔隙比及饱和度通常比较高,分别达26%~40%、42%~70%、0.8~1.1和90%~100%;抗剪强度较大,内聚力为40~85 kPa,内摩擦角为15°~30°;压缩系数和渗透系数一般较小,多小于0.3 MPa -1和1.5×10 -6~5.0×10 -8cm/s。桂林红土的主要工程地质问题是在基岩面附近,尤其是溶沟溶槽中多有软土分布,并常常导致土洞和地面塌陷的发生。桂林红土的这些工程地质特征主要由其特殊的成土环境条件所决定。 相似文献
4.
为了探寻纳米碳酸钙对桂林红黏土力学强度特性的影响机理,利用TSZ-1型三轴试验仪进行不固结不排水三轴压缩试验,分析了在不同干密度条件下各梯度纳米碳酸钙掺量对重塑红黏土黏聚力、内摩擦角、抗剪强度以及应力-应变曲线的影响,从红黏土矿物颗粒胶体化学的角度阐释纳米碳酸钙对红黏土力学强度的影响机理,研究结果表明:随着纳米碳酸钙掺量增加,红黏土黏聚力、内摩擦角以及抗剪强度呈现先减小后增大的趋势;纳米碳酸钙的掺入改变了原有的介质电荷pH值,使得红黏土原有的氧化铁胶结吸附平衡发生改变,形成新的钙质胶结团粒,改变了红黏土的强度特性;加入纳米碳酸钙后起始干密度为1.4g ·cm-3的重塑红黏土样应力-应变曲线由弹性理想塑性型变为应变硬化型。 相似文献
5.
针对土坝黏土铺盖裂缝的淤填固结问题,在充分考虑固相、液相连续性条件和平衡条件的情况下,建立了以孔隙比为控制变量的微分方程。选用两种黏性土进行渗透诱发固结试验,确定各自的孔隙比、渗透系数、有效应力之间的关系。采用软件Matlab的内置函数求解微分方程,得到孔隙比的时空分布曲线。通过试验对数值计算结果进行了验证,结果表明,数值计算得到的孔隙比分布曲线与实测的孔隙比分布曲线基本吻合,具有相同的分布规律,为研究土坝铺盖裂缝处淤填土的固结问题提供了科学依据。 相似文献
6.
对以连云港地区的海相软土为原料的水泥土进行了一系列物理、强度试验,分析了含水量、水泥用量和龄期对水泥土强度的影响,提出了似水灰比的概念用于水泥土强度的预测。采用提出的水泥土强度预测公式,根据某一似水灰比、龄期28 d某种的水泥土室内试验强度,可以预测不同含水量、不同水泥用量和不同龄期的水泥土室内试验强度。通过比较分析发现,得出水泥土强度预测公式可以很好地应用于其他研究者已经发表的水泥土试验数据,进一步验证了所提出的强度预测公式的有效性。 相似文献
7.
广泛分布于北部湾沿岸地区的湛江组结构性黏土具有强烈的触变性,产生的工程问题比较突出。为了研究湛江组结构性黏土的物理力学特性对其触变性的影响,对湛江组结构性黏土触变性进行了一系列的宏观试验研究,通过改变含水率、孔隙比及灵敏度得到重塑土在不同静置龄期的触变强度比率,建立3种物理力学特性分别作为变量下重塑土的触变强度比率与静置龄期的关系,分析湛江组结构性黏土含水率、孔隙比及灵敏度对其触变性强弱的影响。结果表明:(1)湛江组结构性黏土扰动后,随着静置龄期的增加,含水率对湛江组结构性黏土触变强度影响较大,且含水率越大,湛江组结构性黏土触变强度增长的幅度越大;触变强度比率增长的速率表现为前期增长快,后期增长慢。(2)湛江组结构性黏土扰动后,在前期,孔隙比的变化对湛江组结构性黏土触变强度影响不显著,在后期,随着孔隙比增大,湛江组结构性黏土触变强度增长的速率与幅度显著减小。(3)湛江组结构性黏土强度恢复情况与灵敏度有关,湛江组结构性黏土扰动后,随着静置龄期的增加,不同灵敏度重塑土黏聚力、内摩擦角、触变强度比率均增大,扰动后,在静置前期,其黏聚力、内摩擦角、触变强度比率均增长快,扰动后,其黏聚力、内摩擦角、触变强度比率增长慢。 相似文献
8.
压缩指数Cc是土体变形特征的一个重要指标,一般通过固结试验获得,需要耗费较长的时间以及大量人力物力,因此通过其他基本物理指标（天然含水率wn、初始孔隙比e0、液限wL）来推算压缩指数Cc是一个快捷有效的方法。从上海地区钻孔得到第②～⑥层土的原状土样进行固结试验,并结合多个地点的勘察报告数据,发现wn和e0具有较高的线性相关性,但wn与wL间的相关性不明显。考虑到wn相比e0更容易得到,选用wn来建立与Cc的关系式。研究认为,常用的线性关系不适用于上海黏土中含水率wn大于45%的情况,提出了指数函数式（8）。该函数还可适用于中国东部沿海其他地区的黏土。 相似文献
9.
压缩指数Cc和回弹指数Cs是土力学中表征土体变形特性的两个重要参数指标,可通过室内一维固结试验获得。但是试验过程耗时长,因此,很多学者提出了压缩指数Cc与物理指标（尤其是液限wL、天然含水率wn、初始孔隙比e0和塑性指数Ip）的经验关系。通过对比国内外压缩指数经验关系,发现压缩指数与天然含水率和孔隙比关系离散性较小,分别给出了一个统一的经验关系。采用薄壁取土器从上海某一场地取得第②～⑥层土的原状土样进行固结试验,并搜集整理分析已有文献中的试验数据和上海69个场地的岩土勘察数据,给出了上海典型土层压缩指数Cc与wL、wn、e0、Ip的经验关系。同时发现,Cc/n0与Cc以及Cs/n0与Cs（n0为初始孔隙率）之间具有高度的线性关系,从而给出了基于初始孔隙率n0预测上海黏土压缩指数Cc和回弹指数Cs的经验关系。分析了压缩指数和回弹指数的关系,结果表明,上海正常固结黏土Cc/Cs分布在4.8～6.9之间,平均值约为5.8;超固结黏土Cc/Cs分布在3.3～5.2之间,平均值约为4.3。 相似文献
10.
静止土压力系数(K 0)是岩土工程中计算侧向土压力的关键参数,原状和重塑黄土的K 0系数在固结过程中的发展规律明显区别于黏土或砂土。为研究围压和初始孔隙比对原状和重塑黄土的K 0系数的影响,采用加装高精度局部径向位移计(LVDT)的应力路径三轴仪开展了K 0固结试验研究,结果表明:(1)重塑黄土的K 0系数受初始孔隙比(e 0)的影响较为明显,当试样的初始孔隙比减小(从0.775变为0.503),其K 0系数的最大降幅为55%;然而原状黄土的K 0系数受有效围压(σ 3′)的影响较为明显,比如在σ 3′ < 350kPa时,K 0系数为0.77~0.85,在σ 3′>350kPa时,K 0系数为0.46~0.51;(2)在固结过程中,原状黄土试样和重塑黄土试样的K 0系数均发生陡降,具体表现为重塑黄土密样(e 0<0.6)的陡降发生在固结的起始阶段,重塑黄土松样(e 0 ≈ 0.77)的陡降发生在有效围压接近100kPa,而原状黄土试样的陡降发生在有效围压为350kPa附近;(3)在相同的有效围压和密度条件下,原状黄土的K 0系数大于重塑黄土。采用核磁共振技术(NMR)获取了重塑和原状黄土的孔隙分布,并辅以试样的超孔隙水压力、排水体积等数据进行了讨论,发现结构性是造成黄土K 0系数差异的主要原因。 相似文献
11.
已关闭的淮南大通垃圾填埋场建场24 a,最大堆填高度为15 m,垃圾最大填埋龄期达24 a。通过钻孔获取不同深度的6个垃圾样,土工试验结果表明:填埋场内垃圾最小孔隙比为1.18,最大孔隙比为2.53,塑料和纸张类含量对试样孔隙比影响较大;经过24 a的扩散,渗滤液透过了10 m厚的天然致密粘土层而对地下水体产生了污染;实测填埋场垃圾体内气体中CH 4的最高体积分数达2.8654%,CH 4/CO 2比值在0.773～1.79;填埋体内最高温度大约发生在垃圾进场40 d后,达到56℃。针对垃圾填埋场固液气热特性,提出了填埋场治理措施的建议。 相似文献
12.
Artificial linings for the confinement of toxic wastes are often made of clay-cement mixtures, which sometimes contain other powdery substances, such as carbonates. These mixtures are characterized by: (1) high alkaline contents; and (2) strong adsorption capacities, due to the high specific surface of the clay and the artificial silico-aluminous components. The migration of toxic cations normally occurs in acidic solutions. When they come in contact with the clay-cement mixture, the alkaline content of these solutions is progressively activated. The reactions which occur are related to the acid-base neutralization reaction. The sorption of Pb2+ on a clay-cement mixture was studied using the batch equilibrium technique and percolation tests. The change in the retention capacity with increasing pH and the amount of Pb2+ added is similar in both cases. Pb2+ is entirely retained at pH> 7 and this can be attributed to precipitation as hydroxides or hydroxycarbonates. When the alkaline content of the mixture is neutralized, the pH of the solution lowers progressively and the clay-cement mixtures, especially the cement-rich mixture, exhibited stoichiometric uptake of Pb2+ and release of Ca2+, suggesting the formation of lead silicate. 相似文献
13.
海相页岩古地理编图和深水陆棚亚相微相细分一直是细粒沉积学研究的热点和难点。以川南泸州地区五峰组— 龙一14小层为编图单元,通过页岩编图关键单因素的选取和典型钻井矿物组分测井数据的统计分析,编制了关键单因素图件。在此基础上,通过深水陆棚亚相各微相划分标准的确定及多因素图件综合分析,编制了海相页岩定量古地理图。结果表明:1）海相页岩定量古地理编图的关键单因素是地层厚度（m）、碳酸盐矿物含量（%）、石英含量（%）和黏土矿物含量（%）。其中,地层厚度（m）反映了该地层单元在区域上的分布范围、厚度变化及沉积时期的大地构造背景;碳酸盐矿物含量（%）及分布能够反映古水深,水深越浅,碳酸盐矿物含量（%）越高;石英含量（%）及分布主要受古水深控制,水深越大,石英含量越高;黏土矿物含量（%）和分布可以反映古物源方向,黏土矿物含量越高,受陆源碎屑影响越大。2）依据海相页岩的碳酸盐矿物含量（%）、石英含量（%）和黏土矿物含量（%）,深水陆棚亚相可划分出深水斜坡、深水洼地、重力流沉积和深水平原4种沉积微相。其中,深水斜坡碳酸盐含量最高（15%~20%）,深水洼地石英含量最高（>55%）,重力流沉积黏土矿物含量最高（>40%）,深水平原各矿物含量介于其他微相之间。3）五峰组— 龙一14小层发育时期,川南泸州地区发育深水斜坡、重力流沉积、深水洼地和深水平原4种沉积微相,整体呈“3高1洼1复合体”的分布格局,其中,深水斜坡分布于研究区西北部和东北部,重力流沉积发育于研究区东南部,深水洼地发育于研究区中部,其他地区发育深水平原。沉积微相分布是该时期古地形及古构造活动的产物。 相似文献
14.
以深圳南油“３１４”吹淤造陆地区为例，系统分析了吹填淤泥土的物质组成，微观结构特征及其物理力学特征，认为吹填泥土属现代人工堆积淤泥质超软土，具有高含水量，高孔隙比，高压缩性，低承载力的物理力学特征，其物质组成及微观结构与海淤泥有很大差别，在进行造陆加固方案设计时，必须考虑其特殊的工程特征。 相似文献
15.
The impact of the variation in compaction condition on the swelling and shrinkage behavior of three soils has been examined.
Two natural soils, namely red soil and black cotton soil, and one artificially mixed soil sample of commercial bentonite with
well-graded sand, were studied. Compaction curve for Standard Proctor conditions were plotted and four compaction conditions
were selected. Experimental results showed that clay mineralogy dominates over compaction conditions in influencing the swelling
and shrinkage behavior of the tested soils. Monitoring of void ratio (e)−water content (w) relations during shrinkage showed
that soil specimens generally shrunk in three distinct linear stages. A small reduction in void ratio occurred on reduction
in water content during the first shrinkage stage and was termed as initial shrinkage. In second stage, void ratio decreased
rapidly with reduction in water content and was termed as primary shrinkage. In third and final stage, reduction in water
content is accompanied by a marginal change in void ratio and it’s called residual shrinkage. Irrespective of initial compaction
conditions studied, the transition from primary to residual shrinkage for all the specimens occurred within a narrow range
of water content (10–15%). 相似文献
16.
天然软黏土一般都具有一定的结构性,地基处理会改变结构性软土的工程特性。对比扰动软土原位和室内压缩曲线,分析了扰动软土的沉降机理及其压缩性的上下限,给出了考虑扰动影响的结构性软土沉降计算公式。算例分析表明,在孔隙比e0和0.42e0之间所对应的应力水平范围内,扰动会增加地基沉降量,附加沉降量大小与应力水平、扰动度直接相关,通常在0.1～0.3 m之间,但随着应力水平的提高,不同扰动度的结构性软土地基的最终沉降量将趋于相同,得出的有关结论具有工程参考价值。 相似文献
17.
研究Cu2+污染物对桂林红黏土土性异变的影响。通过开展XRD、XRF及压汞试验,探讨Cu2+污染红黏土中主要矿物成分的异变规律及微观孔隙结构的变化趋势,结果表明:红黏土中主要矿物成分为高岭石、石英和针铁矿,Cu2+污染对这3种主要矿物成分的含量产生显著影响,随着Cu2+浓度的增大,高岭石和针铁矿的含量逐渐减少,石英的含量逐渐增多,其含量变化率大小关系为:高岭石>针铁矿>石英,且在浓度为2%时,高岭石的损失率高达10.69%,针铁矿的损失率达到5.38%;红黏土孔隙分布曲线为双峰分布,双峰分别分布在0.01-0.1 μm和1~10 μm之间,且在0.01~0.1 μm之间的微小孔隙占了绝对优势。随着Cu2+浓度的增加,"双峰"逐渐右移,孔隙变大;"峰宽"逐渐变宽,孔隙变多。通过开展相关力学试验,观察Cu2+污染红黏土的变形强度特性异变规律,试验结果表明:Cu2+污染对红黏土的变形强度特性影响显著。随着Cu2+浓度的增加,土体的无侧限抗压强度、抗剪强度、黏聚力C和内摩擦角φ逐渐减小,初始孔隙比e 0和压缩系数α逐渐增大;当Cu2+浓度从0增大至2%时,土体应力-应变关系曲线由典型的应变软化型转变为弱应变硬化型,无侧限抗压峰值强度减少了76.91%,抗剪强度平均损失率达到69.36%。 相似文献
18.
An unusual suite of silicified rocks was excavated during a recent harbour-deepening project in Tampa Bay, Florida. These rocks, which we have termed “box-work geodes”, are composed of convoluted, intersecting silica walls enclosing cavities which are either voids or filled with relatively pure monoclinic palygorskite. The “box-work geodes” are interpreted as having formed in shallow lagoonal environments, similar to the Coorong Lagoon of South Australia. Synaeresis of syngenetic palygorskite was followed by opal deposition and case hardening of the material. Subsequent chemical deposition of chalcedony, megacrystalline quartz, barite, and calcite on the void facing walls indicates an open chemical system. The existence of opal saturated lagoons, as inferred from the “box-work geodes”, suggests that much of the replacement chert, porcelanite, and silicified fossils in the Tertiary deposits of peninsular Florida formed in the shallow subsurface. Subsequent weathering of carbonates and clays not encapsulated in the box works has resulted in formation of a green montmorillonite residual clay bed. 相似文献
19.
Two sections of the Upper Cenomanian and Lower Turonian in central and south-east Poland were investigated for foraminifers, CaCO 3content, carbon content insoluble in HCl (C org) and in the carbonates (C carb), carbon and oxygen isotopic composition of bulk-rock carbonates and elemental abundances. The Cenomanian/Turonian boundary interval is characterized by the appearance of more marly facies, a δ 13C and δ 18O stable isotope anomaly, a considerable increase in C org content and decrease in C carb content and substantial changes in the foraminiferal assemblages. A major carbon stable isotope excursion with a shift of +2 (PDB) occurs in the lowermost Whiteinella archaeocretacea Zone. The late Cenomanian δ 13C anomaly is associated with heavy δ 18O values. The peak value of δ 13C corresponds to the minima in P/B ratio and in diversity of foraminiferal assemblages. A late Cenomanian anoxic event is thought to be responsible for changes in foraminiferal assemblages. However, elemental abundance analyses do not show changes in the concentrations of trace elements. This may be explained by the long distance between studied area and a source of enrichment which was probably located in the western hemisphere. 相似文献
20.
总结宁波地区120个软土地基工程的试验成果,采用数理统计和室内土工试验方法,系统分析研究了宁波地区典型淤泥质粘土的物理力学指标特征、各指标间的相互关系以及固结主要参数,并与我国其他地区软土相关工程特性进行比较,揭示了宁波地区典型软粘土工程特性,即:天然含水率与孔隙比、重度与孔隙比、液限与塑性比相关性非常好;建立的宁波地区软土经验公式不同于其他软土地区。此外,结构性对该地区软土工程性状影响较大,固结系数和次固结系数都受其影响,且影响程度异于其他地区。 相似文献
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