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1.
本文以风化砂改良膨胀土的抗剪强度指标为研究对象,通过室内直接剪切试验,研究了在不同垂直荷重作用下,不同掺砂比例及不同含水率对改良膨胀土抗剪强度指标c、值的影响规律及各种不同垂直荷重下的-关系。影响直接剪切试验结果的两个关键因素是试验时的垂直荷重和剪切速率,而现行规范对剪切速率是有明确规定的,但对垂直荷重只有一个推荐性的取值。本文对膨胀土掺入了10%、20%、30%、40%、50%的风化砂,分别配以6%、8%、10%、12%、14%的水,然后在I级垂直荷重(12.5～50kPa)、Ⅱ级垂直荷重(62.5～100kPa)、Ⅲ级垂直荷重(100～400kPa)作用下,进行剪切试验。通过试验研究得知:垂直荷重对改良后膨胀土抗剪强度指标影响较大,随着垂直荷重的减小,掺砂后的膨胀土内摩擦角逐渐增大,黏聚力逐渐减小; 在各级垂直荷重下,在同一含水率状态下,黏聚力均随着掺砂比例的增大而逐渐减小,而内摩擦角均是先增大后减小; 在同一掺砂比例下,黏聚力及内摩擦角均随着含水率的增大而先增大后减小。本试验的研究成果为风化砂改良膨胀土用作公路路基填料提供了试验依据。 相似文献
2.
混合型缓冲回填材料膨胀力试验研究 总被引：7，自引：1，他引：6
与纯膨润土相比,混合型缓冲回填材料（膨润土与石英砂混合物）能够实现防渗阻隔能力、热传导性能、力学强度和可施工性能的最佳组合。选用高庙子钠基膨润土（GMZ001）为缓冲回填材料的主料,添加不同比例的石英砂,对掺砂比分别为0、10%、20%、30%、40%和50%的膨润土-砂混合物压实试样进行室内试验。结果表明,混合物的液限、塑限随掺砂率的增大而线性降低;膨胀力随时间呈指数增长。初始含水率较大时,最大膨胀力随初始含水率的增大略有降低。掺砂率一定时,最大膨胀力随初始干密度指数增长。提出了有效黏土密度的概念,建立了一定初始含水率条件下,任意掺砂率和初始干密度的高庙子膨润土-砂混合物最大膨胀力归一化模型,为混合型缓冲回填材料膨胀力的预测与控制提供了依据。 相似文献
3.
研究掺粉煤灰对合肥膨胀土的物理性质指标以及胀缩性指标等的影响,探讨利用粉煤灰改良膨胀土的措施与效果。试验研究结果表明,在膨胀土中掺入适量的粉煤灰可有效降低膨胀土的塑性指数、降低膨胀势、减小线缩率与降低活性。在膨胀土中掺入粉煤灰还可改变膨胀土的击实特性,一定击实功作用下,随着掺灰率的增加,土体的最优含水率与最大干密度均减小,膨胀土中掺入粉煤灰后,膨胀土可在较小的含水率下通过击实或压实达到稳定。掺灰膨胀土的膨胀量与膨胀力随养护龄期的增长而减小;没有经过养护的掺灰土,其无侧限抗压强度随掺灰率的变化几乎没有变化,经过7 d养护后,土的无侧限抗压强度有所增长,并且存在一个峰值点,合肥膨胀土的无侧限抗压强度所对应的最佳掺粉煤灰率约为15 %～20 %。 相似文献
4.
本文以三峡库区广泛分布的风化砂来改良膨胀土,通过在膨胀土中掺入10%、20%、30%、40%、50%的风化砂,进行1、3、6、9、12次冻融循环,最后对不同冻融循环次数作用后改良膨胀土制备样进行直接剪切试验,测定不同掺砂量及不同冻融次数下,各试样的强度参数,得出冻融循环对风化砂改良膨胀土抗剪强度指标及强度规律的影响.试验结果表明:在同一掺砂比例下,风化砂改良膨胀土的抗剪指标和抗剪强度随冻融循环次数的增大而减小,最后逐渐趋于稳定,其中黏聚力与冻融循环次数呈对数关系; 在同一冻融循环次数下,黏聚力随掺砂比例的增大而减小,内摩擦角随掺砂比例的增大而增大. 相似文献
5.
6.
碱渣改良膨胀土室内试验研究 总被引：10，自引：0，他引：10
通过室内试验,探讨利用碱渣作为添加剂对膨胀土改良的可行性和改良效果和碱渣改性土的基本物理力学性质和膨胀性。研究结果表明,随着掺渣率的增加,碱渣改性土的黏性成分的含量降低,粗颗粒含量增加,导致相对密度、液限、塑性指数、自由膨胀率、有荷膨胀量均呈明显减小趋势,这说明碱渣对膨胀土膨胀性的改良有显著效果;碱渣改性土可击实含水率范围较之膨胀土宽,这给碱渣改性土的施工带来很大方便;经过7 d养护后的土样无侧限抗压强度和抗剪强度都显著增加,并在掺渣率为30%时存在一个峰值点。抗剪强度增强主要体现在黏聚力显著增加,而内摩擦角变化不大。 相似文献
7.
通过向膨胀土中添加2%~18%不同比率的水泥窑灰(CKD)对其进行改性,对纯膨胀土及掺CKD改性膨胀土的水理性质、膨胀特性和收缩特性进行室内试验,确定改性效果。试验结果表明,CKD可以降低膨胀土的自由膨胀率和液限,液限降低规律符合指数函数,塑限略有提高;随着CKD掺量的增大,混合物的最大膨胀率和最大膨胀力均呈指数衰减,最终收缩率也大幅降低。改性后的膨胀土黏粒减少,水稳性提高,同时由于离子交换等作用,膨胀土-CKD混合物的亲水性降低,吸水性减弱,从而胀缩性质降低,说明CKD对降低膨胀土的胀缩特性具有很好的改性效果,建议适宜掺灰率为10%。 相似文献
8.
不同剪切速率对风化砂改良膨胀土抗剪强度指标的影响 总被引：1，自引：0，他引：1
土的抗剪强度指标受含水率、剪切速率以及土样的类别等多个因素的影响。为了研究不同剪切速率对风化砂改良膨胀土的抗剪强度指标的影响规律,分别在2.4,0.8 mm/min剪切速率下对不同含水率和不同掺砂比例的风化砂改良膨胀土样进行了室内直剪试验,得到了不同剪切速率下改良膨胀土的抗剪强度指标值。试验表明:采用2.4 mm/min的剪切速率测得的抗剪强度指标比采用0.8 mm/min的剪切速率测得的值要大;通过对比试验数据可知,剪切速率对内摩擦角的影响比对黏聚力的影响相对来说较小,对砂土的抗剪强度指标的影响比对黏土的抗剪强度指标要小,对含水率较小的土样的抗剪强度指标的影响比对含水率大的土样的抗剪强度指标要大。对于风化砂改良膨胀土的抗剪强度指标的测定时的剪切速率应采用规范要求的0.8 mm/min。 相似文献
9.
膨胀土遇水膨胀失水收缩,是一种不良的工程地质土体。本文采用水泥、钢渣粉和NaOH改良膨胀土,对其经受不同冻融循环作用次数的冻融循环试验,并将冻融试验后的改良膨胀土及未改良膨胀土进行体积、自由膨胀率、无侧限抗压强度等物理力学性质测试,同时进行微观电镜扫描分析,研究冻融循环作用下钢渣粉水泥改良膨胀土的物理力学特性变化规律。试验结果表明,在冻融循环作用下,改良后的膨胀土与未改良膨胀土相比,体积变化率明显降低。随养护龄期的增长,改良后的膨胀土在冻融循环作用下体积膨胀变小,随冻融循环次数的增加,体积变化率趋于平稳,自由膨胀率降低。冻融循环作用下,钢渣粉水泥改良膨胀土(ES-SSP-C)试样的无荷膨胀率较低,改良后的膨胀土较未改良膨胀土具有较好的抗膨胀性能,掺NaOH活性激发剂的钢渣粉水泥改良膨胀土(ES-SSP-C-SH)抗膨胀性能效果最为明显。 相似文献
10.
合徐高速公路膨胀土路基填料的试验研究 总被引：1，自引：0，他引：1
膨胀土路基掺石灰率应通过物理与力学性质、胀缩性、水稳性等试验来确定，本文对合徐高速公路(合肥段)膨胀土路基填料不掺石灰和掺石灰处理后的胀缩性及物理、力争性质进行了试验研究，得出了掺石灰对改善膨胀土路基填料工程性质的影响，并对不掺石灰和掺石灰处理后的填料进行了膨胀及收缩变形量的估算，论述了膨胀土特性及处理方法，供同行参考。 相似文献
11.
The use of shredded waste tires to improve the geotechnical engineering properties of sands 总被引：2，自引：0，他引：2
Mousa F. Attom 《Environmental Geology》2006,49(4):497-503
A new geo-environmental approach was proposed to use waste tires in certain engineering applications and thereby reduce the
potential impact on the environment. This paper presents a laboratory study on the effect of shredded tires on the physical
properties of some sands. Shredded tires were passed through US sieve size 4 and mixed with three different types of sands
with varying gradations. Each type of sand was mixed with four different percentages of shredded tires: 10, 20, 30 and 40%
by dry weight. Direct shear tests were conducted to study the effect of the shredded tires on the shear strength properties
of sands, such as angle of internal friction and shear strength. The addition of shredded waste tires increased both the angle
of internal friction and the shear strength of the sands. Additionally, a prediction model was developed to calculate the
shear strength of sand due to increasing shredded tire content. The shredded tires improved some engineering properties of
sand. 相似文献
12.
13.
Ali Firat Cabalar 《Geotechnical and Geological Engineering》2011,29(4):411-418
Waste tires are used in some engineering applications and thereby reduce the potential impact on the environment, for example,
as lightweight materials in geotechnical engineering projects. This paper presents a brief literature review on geotechnical
applications of processed waste tires, and a laboratory study on the effect of tire shreds on the physical properties of two
different sands (fine angular sand and coarse rotund sand). Each type of sand was mixed four different percentages of rubber
particles; 5, 10, 20 and 50% by dry weight. Direct shear tests were employed to investigate the effect of rubber particles
on the shear strength of sands and internal friction angle. The addition of shredded waste rubber particles slightly decreased
both the internal angle of friction and the shear strengths of the sands within the tested stress and strain levels. Additionally,
a prediction model using stepwise regression (SR) method is proposed to calculate the shear strength of sands with the increasing
rubber content. The performance of accuracies of proposed SR models are quite satisfactory. The proposed SR models are presented
as relatively simple explicit mathematical functions for further use by researchers. 相似文献
14.
The paper presents the results of the study which influence the use of recycled waste expanded polystyrene foams (EPS), as a lightweight material used with river sand. In this study, thermally modified waste EPS have been used. The waste EPS were put in an oven at 130 °C through 15 min to obtain modified expanded polystyrene (MEPS). The influences of MEPS on compaction properties such as maximum dry density and optimum moisture content were investigated. For this purpose, five series of compaction tests were carried out. MEPS were added to river sand at 5, 10, 15, and 20 % by weight. The test results showed that addition of 20 % MEPS in sand reduces the density of mixture almost 50 %. MEPS can be an alternative light weight fill material for geotechnical applications. 相似文献
15.
Mahmoud Ghazavi 《Geotechnical and Geological Engineering》2004,22(3):401-416
Waste materials such as waste tires, rubbers, and plastic materials are normally produced in every society, entering the environment
and causing serious problems. These problems may be somehow reduced by finding applications for them in engineering, for example,
as lightweight materials for backfill in geotechnical projects. To this aim, this paper demonstrates how shear strength characteristics
of sand mixed with various percentages of waste garden hose grains are altered. A relatively, uniform sand has been mixed
with waste hose grains in loose and slightly compacted states. Waste hose grains were prepared with special popular machinery
in a local area. Various sand-rubber mixtures having 0%, 10%, 15%, 20%, 50%, 70%, and 100% waste hose particles by weight
were chosen. The rubber grains were distributed in the sand such that uniform mixtures are obtained. In order to compare the
shear strength of different sand-rubber samples, two compaction states were considered. The results show that the influencing
parameters on shear strength characteristics of sand-rubber mixtures are normal stress, mixture unit weight, and rubber content.
With the selected waste hose particles, compaction states, and rubber contents, the initial friction angle φ1 does not change significantly. However, an apparent cohesion appears in the mixtures. From environmental point of view and
due to lightweight material for the sand-waste hose particles, it may be useful to use such materials in corresponding geotechnical
projects.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
将建筑废渣按一定比例与黏土掺合形成的渣土混合料用作填筑材料,具有显著的社会经济与环保效益。为了揭示渣土混合料的压实特性,利用击实试验研究渣料含量和初始级配对渣土混合料压实性能及颗粒破碎特性的影响。研究结果显示,与黏土相比,渣土混合料的最优含水率较低而最大干密度较高,尽管渣料的初始级配有所不同,渣土混合料的最优含水率随掺渣量的增加而减小,最大干密度随掺渣量的增加而先增后减,并存在着一个约为30%的最优掺渣量;击实作用下渣料颗粒的相对破碎率随掺渣量的增加而增加,与初始级配均匀的渣料相比,相同掺渣量下初始级配不均匀渣料的相对破碎率较小,但受渣料初始颗粒大小的影响不大;与初始较小颗粒渣料的混合料相比,初始较大颗粒渣料的混合料的最大干密度较大,表明宽级配的渣土混合料压实性能较好。渣土混合料的压实特性通过结合掺渣量、颗粒破碎特性与渣土混合料结构响应分析得到合理解释。 相似文献
17.
Yahia E.-A. Mohamedzein Mohammed Y. Al-Aghbari 《Geotechnical and Geological Engineering》2012,30(6):1335-1344
Dune sands are problematic soils because they have low shear strength and are susceptible to collapse upon wetting. Dosages of municipal solid waste incinerator ash between 10 and 80?% were used to improve the engineering properties of dune sands. The soil-ash mixtures were allowed to cure for periods from 7 to 90?days. Laboratory tests such as compaction, unconfined compression, shear box and hydraulic conductivity tests were performed to measure the engineering characteristics of the stabilized material. The results showed that the maximum dry density remains approximately constant up to ash content of 30?% and then it decreases with the increase in ash content. The optimum water content increases with the increase in ash content. The unconfined compressive strength substantially increases with ash content up to 30?% and then decreases with the increase in ash content. The angle of friction follows similar trend to the unconfined compressive strength. However, the cohesion shows a steady increase with the ash content. The hydraulic conductivity of the stabilized material consistently decreases with the increase in the ash content. The effect of curing time on the hydraulic conductivity is minimal after 7?days of curing time. However, the unconfined compressive strength and the cohesion slightly increased with curing time up to 90?days. 相似文献
18.
砂-膨润土混合屏障材料渗透性影响因素研究 总被引：2，自引：0，他引：2
膨润土因具有渗透性低、阳离子交换能力高等优点被认为是最适合高放废物深地质处置库中屏障系统的缓冲材料,工程实践发现随着水化过程的进行,纯高压实膨润土强度不断降低,并最终影响到工程屏障系统功能的发挥。针对这一问题,在膨润土中加入一定比例的石英砂,可以有效地提高工程屏障的热传导特性、压实性、力学强度和长期稳定性,降低工程造价。本文研究了影响砂-膨润土混合物渗透性的主要因素,包括膨润土含量、粒径分布、含水量和干密度、压实方法以及膨润土类型等。结果表明,砂土混合物渗透性主要受膨润土的渗透性控制,渗透系数随着膨润土含量和干密度的增加而减小,当膨润土含量超过某一界限值后,继续增加膨润土含量对降低渗透系数的作用有限;细颗粒和级配良好的混合物渗透系数小,当土体内部发生渗透侵蚀将增大渗透系数;最优含水量条件下压实得到的渗透系数最低,高于最优含水量压实得到的渗透系数比低于最优含水量压实得到的渗透系数要小。 相似文献
19.
基于压实度和弯沉值检测在某高速公路检验路基质量标准的应用实践,通过现场填筑试验,分析土石混填路基的压实固结机制并探讨不同施工因素（碾压次数、虚铺高度、颗粒级配、洒水遍数、振动方式）及其组合形式对压实质量的影响。研究结果表明:（1）随着碾压遍数逐渐增大,路基弯沉值先减小后平稳,压实度先增大后平稳;（2）先两遍静压再六遍高频率振动碾压,松铺厚度为30 cm,洒水两到三遍可以进一步改善压实效果;（3）颗粒破碎是影响路基压实度增大的因素之一,压实度增大是粗颗粒破碎成细颗粒,填充颗粒间孔隙,使粗细颗粒彼此咬合的结果。通过对试验结果的分析,提出了路基压实度与回弹模量的高斯指数关系,可作为高速公路快速安全施工的理论参考。 相似文献
20.
利用DSJ-2型电动四联等应变直剪仪分别进行了不同粒径砂和粘土(方案1)、不同含水量砂和粘土(方案2)的直剪试验,揭示了其接触面的力学特性。试验结果表明:法向应力(σn)、砂粒径大小、砂含水量对接触面的力学特性有着重要的影响。方案1和方案2接触面的抗剪强度和达到剪切应力峰值时的剪切位移随着法向应力的增大而增大,当σn为100 kPa时,粘土和不同粒径砂的接触面剪切应力和水平剪切位移(τ-δ)关系曲线呈现应变软化现象;方案1接触面抗剪强度随砂粒径的减小而降低,方案2在σn为100 kPa时,接触面抗剪强度随砂含水量增加而降低,σn>100 kPa时,接触面抗剪强度随砂含水量增加先降低后变大;方案2在低法向应力下,接触面抗剪强度对应的含水量敏感区间为[10%,15%],且较明显。 相似文献