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1.
水泥固化铅污染土的基本应力-应变特性研究 总被引：7，自引：0，他引：7
采用水泥系固化剂,对铅污染土进行了固化处理,对固化后污染土的无侧限压缩变形特性进行了研究。试验所用的铅污染土通过人工制备而成,并考虑了不同的铅离子浓度和水泥掺量。研究结果表明,随着污染土中铅含量的变化,水泥固化铅污染土的应力-应变特性、破坏应变、变形模量值不同。铅浓度为0.01%、0.1%试样的破坏应变大于不含铅试样,且随着强度的增加、龄期的增长呈幂函数减小。韧性指数可用来定量描述铅离子浓度对固化土样韧性特征的影响程度。固化铅污染土的变形模量与其无侧限抗压强度呈线性关系,线性拟合参数与铅离子浓度和水泥掺量有关。 相似文献
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3.
以标准砂及普通硅酸盐水泥为试验材料,制作水泥固化锌污染土样,进行了一系列电阻率和无侧限抗压强度试验。研究了交流电频率对水泥固化锌污染土电阻率的影响、不同含量锌离子对水泥缓凝作用的影响、锌离子含量和龄期分别对水泥土电阻率和强度的影响、电阻率与无侧限抗压强度的关系。结果表明：电阻率随电流频率的增加而明显降低,尤其当频率低于50 kHz时为甚;不同含量的锌离子对水泥土的缓凝作用影响明显,随着锌离子含量的增大,水泥土强度的充分发挥所需时间逐渐增长,但在锌离子含量为500 mg/kg时,缓凝作用表现异常;电阻率和强度均随龄期的增加而增长,随锌离子的含量的增加上下波动,电阻率在锌离子含量为50 mg/kg和500 mg/kg时出现极值,强度在锌离子含量为100 mg/kg和500 mg/kg时出现极值;在各个龄期下,电阻率与强度均呈现出很好的线性关系。 相似文献
4.
轻量砂变形及强度特性三轴试验研究 总被引：1，自引：0，他引：1
通过三轴试验系统研究了新型土工材料--轻量砂的变形及强度特性。结果表明,不同的配比、龄期使轻量砂具有不同的原生结构强度,围压使不同原生结构强度的土样处于剪胀或剪缩状态,导致发生应变硬化、应变软化以及相应状态下孔压的3种对应形态变化。变形模量随EPS（发泡聚苯乙烯）球粒掺入比的增大而线性减小,随水泥掺入比、龄期增大而线性增大,相同配比的土样变形模量与围压关系不大;三轴抗压强度随EPS球粒掺入比增大而呈负指数关系减小,随水泥掺入比、龄期、围压增大而线性增大,存在水泥掺入比阀值;土骨架转换效应对于土样强度的影响很大,造成了土体单轴、三轴抗压强度分带,高水泥掺入比能够大大弱化EPS颗粒的土骨架效应。结合前人成果,系统地研究了轻量砂密度、无侧限抗压强度的影响因素,引入材料学中比强的概念,提出了单价比强图结合配方公式的方法,对轻量土砂进行配方优化。分析了轻量土砂应力-应变关系转型问题,提出采用无侧限抗压强度来表征不同配比、龄期轻量土砂的原生结构强度。通过试验与数理统计,建立临界围压与原生结构强度的关系,为数值模拟计算与建立本构模型奠定了基础。 相似文献
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采用磷酸镁水泥（MPC）对铅污染土进行固化/稳定化处理。基于无侧限抗压强度试验,系统地研究了MPC添加量、养护龄期、水土比和污染土铅含量对固化污染土应力-应变特性的影响规律。结果表明,固化污染土的应力-应变曲线呈现出3个阶段,即压密阶段、弹性阶段和破坏阶段;随着MPC添加量和养护龄期的增加,固化污染土的抗压强度qu增大,变形模量E50增大,破坏应变εf减小;水土比和铅含量对固化土的抗压强度qu和E50均存在临界值,分别为0.45和500 mg/kg,低于临界值时,固化土的qu和E50随着铅含量和水土比的增加而增加,εf随着qu增加呈幂函数规律减小,E50随着qu的增加呈线性增加,E50随着εf的增加呈幂函数规律减小。 相似文献
6.
寒区水泥固化土力学性能影响因素分析 总被引：4，自引：1，他引：3
为了在北方寒区推广和应用水泥固化土建造保暖性房屋和设施农业,采用内蒙古黄河灌区周边典型的粉质土,利用普通硅酸盐水泥固化土体,配制水泥固化土,采用静力机械压实法和人工分层击实法分别制作了Φ50mm×H50mm和Φ39.1mm×H80mm两种不同规格的试件,并进行了无侧限抗压强度室内试验,研究了不同水泥掺入比、不同养护龄期、不同规格及成型方法对水泥固化土无侧限抗压强度的影响,得出了不同试验条件下水泥固化土的强度变化规律.试验结果表明:强度均随水泥掺入比及龄期的增大而增大,三者之间较好地满足空间平面模型,偏回归分析表明,水泥掺入比较龄期对强度的影响贡献更大,两种规格试件的强度之间较好地满足对数关系;不同规格及成型方法的试件对水泥固化土强度的影响规律不同,Φ39.1mm×H80mm试件存在一个临界水泥掺入比与临界养护龄期,当超过这个值时,其强度增长率减小. 相似文献
7.
固化淤泥重塑土力学性质及其强度来源 总被引：3，自引：2，他引：1
对不同水泥掺加量的固化淤泥及其重塑土进行了无侧限抗压强度试验和直接剪切试验,并对固化土和重塑土的应力-应变关系曲线、无侧限抗压强度、黏聚力和内摩擦角进行了比较分析。结果表明：随着水泥量和龄期的增加,固化淤泥的脆性增强,塑性减弱;重塑土的应力-应变关系受水泥量和龄期的影响不大,随着应变的增加,应力增长缓慢,塑性变形非常大。固化土的无侧限抗压强度、黏聚力均随着水泥量和龄期的增加而增大,而内摩擦角则有减小的趋势。重塑土相对于原状土无侧限抗压强度和黏聚力都有较大程度的折减,并且水泥量和龄期越大,折减越多;内摩擦角随着水泥量和龄期的增加有小幅度提高。重塑土强度主要来源于破碎固化土团间的摩擦和咬合作用,因此,在固化淤泥重塑土的实际工程应用中,初始固化土的处理强度不应太高。 相似文献
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为研究EPS颗粒混合轻量土的密度、强度和变形特性,对不同水泥掺量、EPS颗粒掺量、含水率和龄期的轻量土进行密度无侧限抗压强度试验。试验配置轻量土无侧限抗压强度范围为103.2~1359.0 kPa,且随水泥掺量的增大呈指数关系增大的趋势,随EPS颗粒体积比的增大而呈线性关系减小的趋势。在大于最优含水率情况下,含水率越高,无侧限抗压强度越低,两者为指数关系,而龄期的增长能够使得轻量土的无侧限抗压强度呈双曲线增大的趋势。EPS颗粒混合轻量土的应力-应变关系曲线主要表现为应变软化型,含水率和EPS颗粒体积比的增大会使得轻量土的应力-应变关系曲线逐渐向硬化型转化。水泥掺量和龄期的增大能够增强轻量土的脆性特征,增大刚度。而含水率和EPS颗粒体积比的增大则使得轻量土的延性特征增强,刚度减小。研究成果对实际工程应用具有参考价值。 相似文献
9.
为实现岛礁公路建设资源集约化,提出采用水泥固化稳定珊瑚礁岩、砂作为路面基层材料。通过无侧限抗压强度、劈裂强度、回弹模量、水稳性、干缩和温缩试验,探究水泥固化稳定珊瑚礁岩、砂吹填材料强度、刚度、水稳性和收缩性等路用性能,为后续岛礁工程建设提供理论依据和数据支持。结果表明:在标养条件下,相同龄期的试样抗压强度和劈裂强度随水泥用量增加而提高,水泥用量相同的试样随龄期增长而提高;抗压强度增长基本符合线性规律。回弹模量随水泥用量增加而提高,但增幅逐渐减小。相同龄期下,试件饱和抗压强度相对于低于标准抗压强度;水泥用量和龄期越大,强度损失率越小,抗软化能力越强,如水泥用量6%试样28 d强度损失率与软化系数是水泥用量3%的93%和101%。试样失水率与干缩应变随龄期与水泥用量增加而增长,如水泥用量6%试样180 d失水率和干缩应变是水泥用量3%的1.35倍和1.27倍。温缩试验表明:温缩应变和温缩系数随水泥用量增加而增大,而随温度降低先增大后减小,处于30~45℃温度区间是岛礁公路建设最不利的状态,应尽量避免高温施工。 相似文献
10.
硫酸盐侵蚀环境下水泥土的力学行为研究 总被引：2，自引：0，他引：2
针对含硫酸盐介质的环境水服役条件,通过室内模拟试验手段,研究了不同配合比参数和不同条件下水泥土的无侧限强度、弹性模量以及应力-应变的变化规律,分析了硫酸盐侵蚀环境下水泥土力学性能的劣化机理。结果表明,配合比参数以及环境条件对水泥土的无侧限抗压强度、弹性模量、应力-应变曲线有显著的影响;硫酸盐溶液中的水、硫酸根离子与水泥土之间的复杂物理、化学作用,影响水泥土内部微细观结构,从而对水泥土的力学性能存在显著劣化作用;且这种侵蚀作用在90d龄期内最为显著。 相似文献
11.
Potential Application of Lateritic Soil Stabilized with Cement Kiln Dust (CKD) as Liner in Waste Containment Structures 总被引：1，自引：1，他引：0
Agapitus Ahamefule Amadi Adrian Oshioname Eberemu 《Geotechnical and Geological Engineering》2013,31(4):1221-1230
This study evaluates the applicability of residually derived lateritic soil stabilized with cement kiln dust (CKD), a waste product from the cement manufacturing process as liner in waste repositories. Lateritic soil sample mixed with 0–16 % CKD (by dry weight of the soil) was compacted with the British Standard Light, West African Standard and British Standard Heavy compaction efforts at water contents ranging from the dry to wet of optimum moistures. Geotechnical parameters such as Atterberg limits, compaction characteristics, hydraulic conductivity, unconfined compressive strength and volumetric shrinkage strain were determined. Results indicate that the plasticity index, the maximum dry unit weight and hydraulic conductivity together with the volumetric shrinkage decreased with increased amount of CKD while the optimum moisture content and unconfined compressive strength increased with higher CKD content for all the efforts. When measured properties were compared with standard specifications adopted by most environmental regulatory agencies for the construction of barrier systems in waste containment structures, the resulting values showed substantial compliance. Besides developing an economically sustainable liner material, the present study demonstrated effective utilization of an industrial by-product otherwise considered as waste by the producers, in addition to a systematic expansion in the use of the lateritic soil for geotechnical works. 相似文献
12.
The presence of heavy metals at high concentrations (percent levels) in soils has been a growing concern to human health and the environment, and the cement stabilization is considered to be an effective and practical approach to remediate such soils. The compressibility of such stabilized soils is an important consideration for redevelopment of the remediated sites for building and/or roadway construction. This paper investigates the effects of high levels of zinc concentration on the compressibility of natural clay stabilized by cement additive. Several series of laboratory compression (oedometer) tests were conducted on the soil specimens prepared with the zinc concentrations of 0, 0.1, 0.2, 0.5, 1, and 2 %, cement contents of 12 and 15 %, and curing time of 28 days. The results show that the yield stress and compression index at the post-yield state decrease with an increase in the zinc concentration regardless of the cement content. The observed results are attributed to the decrease in the cement hydration of the soil. Overall, this study demonstrates that the cementation structure of the soils is weakened, and the compressibility increases with the elevated zinc concentration, particularly at relatively high levels of zinc concentration. 相似文献
13.
Consoli Nilo Cesar Párraga Morales Durval Saldanha Rodrigo Beck 《Acta Geotechnica》2021,16(5):1473-1486
The presence of lateritic soils occurs in tropical and subtropical regions. The improvement of lateritic soils that are not suitable for a particular purpose through techniques that combine modification of grain size through the insertion of sand, incorporation of Portland cement and densification through compaction is seen as an alternative. In this context, a dosage method to use a local lateritic soil as construction material in a most rational way reducing the economic and environmental impacts related to this activity is still missing. Therefore, the current research aims to evaluate the performance of a lateritic soil via modification of grain size through the insertion of sand, incorporation of Portland cement and densification through compaction. For this, unconfined compression, and durability (wetting and drying) tests were carried out on specimens of compacted clayey gravel lateritic soil, whose granulometry was modified by the insertion of distinct amounts (from zero to 45%) of weathered sand, treated with distinct Portland cement contents (from 4 to 10%), molded at different dry unit weights (from 16.8 to 20.1 kN/m3) and cured for 7 and 28 days. Results of the mechanical tests have shown the significant influence exerted by cement content and dry unit weight of the blend, followed by curing time and finally sand insertion. Satisfactory correlations between the response variables (qu and ALM) and the adjusted porosity/cement index (η/Cv) were obtained. Furthermore, an innovative approach to replacing the laborious durability test is proposed.
相似文献14.
Mousa F. Attom 《Environmental Geology》2008,55(4):781-788
Iron filling and iron filling–cement mixture were used to improve the shear strength characteristics of Irbid clayey soil.
For this purpose, five types of Irbid clay soils were obtained and mixed with iron filling and iron filling–cement mixture
at different percentages. Two sets of prepared samples were mixed with the admixture. The first set was prepared by mixing
the soil samples with iron filling alone at 2.5, 5.0, 7.5, and 10% by dry weight of the soil. The second set was prepared
by mixing with iron filling–cement mixture at equal ratio of the same percentages of the first set. An unconfined compression
test was performed in this study to measure the shear strength properties of the soils. The test results showed that the increase
in the percentages of the iron filling and iron filling–cement mixture up to 10% will result in increasing the maximum dry
density of the soil and increase the unconfined compressive strength and the secant of modulus of elasticity of the clayey
soil. Also, the addition of iron filling–cement mixture increased the unconfined compressive strength and secant modulus of
elasticity of the clayey soil higher than the addition of iron filling alone. 相似文献
15.
Yahia E.-A. Mohamedzein Amer A. Al-Rawas 《Geotechnical and Geological Engineering》2011,29(6):999-1008
Sabkha soils are salt-bearing formations that are formed in arid regions. In their in situ states the sabkha soils have high
compressibility and low shear strength. These soils are also heterogeneous and their properties depend on the type and amount
of salt present. Thus, these soils are not suitable for support of infrastructures without the risk of high settlement and/or
bearing capacity failure. This paper investigates the possibility of using cement to improve the shear strength of sabkha
soils for possible use as a foundation-bearing soil. The sabkha soil used in this study is a sandy sabkha obtained from the
coastal plains at Al-Auzayba, Sultanate of Oman. Cement was added in percentages of 2.5, 5, 7.5 and 10%, by dry weight of
soil. The soil-stabilizer mixers were allowed to cure for 7, 14 and 28 days. Laboratory tests such as compaction, unconfined
compression, consolidated undrained triaxial and durability tests were performed to measure the engineering characteristics
of the stabilized material. The results showed substantial improvements in the shear strength of the sabkha–cement mixtures
and the mixtures are also durable with small weight loss after 12 wetting/drying cycles. Thus, cement can be used to improve
the shear strength of sabkha soils. Furthermore, the effective stress path and the tress-strain relation of the sabkha–cement
mixtures follow trends similar to those of cemented calcareous soils. 相似文献
16.
Behzad Fatahi Thu Minh Le Behnam Fatahi Hadi Khabbaz 《Geotechnical and Geological Engineering》2013,31(5):1421-1435
In this study, effects of two types of geofibers, namely polypropylene and recycled carpet, on three dimensional shrinkage properties of cement treated kaolinite and bentonite clays are investigated. Cement treated clay specimens were prepared with cement contents of 5, 10, and 15 % by weight of dry soil for kaolinite samples, and 30, 40 and 50 % for bentonite samples. To investigate and understand the influence of different fiber types and contents, three different percentages of fiber content (i.e. 0.1, 0.2 and 0.5 % polypropylene fibers; and 0.5, 0.75 and 1 % carpet fibers) were adopted. The results of shrinkage tests on 126 cylindrical samples of cement treated clay with various cement and fiber contents were analysed to understand the relationships between these parameters and the shrinkage percentage of treated soil. Results of this study indicate that combination of cement and fiber is effective in reducing the volume change of clayey soils undergoing drying process. In the applied ranges of cement and fiber contents, the influence of cement addition on the shrinkage reduction is more significant than the addition of fibers for the treated kaolinite. However, addition of fibers in curtailing the shrinkage of bentonite clay is more significant than the cement addition. 相似文献
17.
超微粒子水泥加固软土试验研究 总被引：1，自引：0，他引：1
应用和研发各种固化材料,对软土进行固化和改性,以改善其工程特性是当今国际上研究的热点课题。通过室内试验,研究了一种新型超微粒子水泥材料（ALOFIX-MC,简称MC）加固软土的效果,分析了其加固和改性机制。试验中,MC以0 %、1 %、2 %、3 %、4 %和5 %的掺量分别掺入到水泥掺量15 %和石膏掺量2 %的软土试样中,配制了6组试样。室内无侧限抗压强度试验结果表明,在15 %掺量的普通水泥土中掺入少量MC就可以显著提高软土的强度和稳定性。扫描电镜（SEM）分析表明,MC的胶结填充作用和MC对水泥水化的促进、孔隙的填充以及其本身的表面吸水作用对加固效果有重要影响。研究成果为进一步提高水泥土的工程性质和减少常规水泥土中水泥掺量提供了一条新的途径。 相似文献
18.
评估了水泥稳定再生沥青路面（RAP）/边缘红土混合物作为碎石桩骨料替代传统采石场骨料的潜力,研究了混合材料在不同RAP置换率和有效约束压力下的不排水剪切强度变化。RAP置换率分别为10%、30%和50%（按干重计）,普通硅酸盐水泥含量分别为1%和3%。很明显,RAP的置换增加了大颗粒,同时减少了细小颗粒,因此增加了压实度。在低于先期固结压力的有效应力下,RAP−土颗粒混合物表现出与孔隙压力降低相关的应变硬化性能。当RAP置换率增加时,水泥稳定的RAP−土颗粒混合物应力−应变曲线的应变软化性能减弱。胶结作用提高了黏聚力,而内摩擦角未产生明显的变化。水泥稳定的RAP−土颗粒混合物的强度和刚度主要取决于胶结强度和RAP置换率。抗剪强度随着非稳定和水泥稳定的RAP−土颗粒混合物的RAP置换率增加而提高,而水泥稳定的RAP−土颗粒混合物的刚度由于沥青黏结剂的高能量吸收而下降。 相似文献
19.
水泥改良土具有强度高、变形小、施工操作简单、质量控制容易和经济效益显著等优点,被广泛应用于路基填筑、基坑回填、边坡防护和地基换填。水泥土裂缝影响路基工程的正常运行,甚至可能危及铁路路基安全。因此,铁路路基设计需要对路基填土的抗拉强度有一定程度的了解,水泥改良土抗拉强度的确定具有重要意义。水泥改良土的抗裂性能是影响工程应用的重要因素,拉伸强度是衡量水泥土抗裂性能的关键指标。本文基于常规无侧限压缩仪自行设计了直接测量水泥改良土拉伸强度的单轴拉伸试验方法,系统地研究了水泥掺量（A）、龄期（t）、含水率（w）和干密度（ρd）对水泥改良土单轴拉伸强度（σt）的影响,水泥改良土的单轴拉伸强度随水泥掺量、龄期和干密度增加而增加,随含水率增加而减小,建立了水泥改良土的单轴拉伸强度与et/A（et是水泥改良土的孔隙比）之间的指数函数关系。结合水泥改良土的无侧限抗压强度和基质吸力的测试结果,建立了单轴拉伸强度与无侧限抗压强度和基质吸力之间的相关关系。 相似文献