共查询到20条相似文献，搜索用时 140 毫秒
1.
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
2.
《Geomechanics and Geoengineering》2013,8(2):175-181
Expansive soils swell on absorbing water and shrink on evaporation thereof. Because of this alternate swelling and shrinkage, civil engineering structures founded in them are severely damaged. For counteracting the problems of expansive soils, different innovative techniques were suggested. Stabilization of expansive clays with various additives has also met with considerable success. This paper presents, by comparison, the effect of lime and fly ash on free swell index (FSI), swell potential, swelling pressure, coefficient of consolidation, compression index, secondary consolidation characteristics and shear strength. Lime content (weight of lime/weight of dry soil) was varied as 0%, 2%, 4%?and 6%?and fly ash content (weight of fly ash/weight of dry soil) as 0%, 10%?and 20%. A fly ash content of 20%?showed significant reduction in swell potential, swelling pressure, compression index and secondary consolidation characteristics and resulted in increase in maximum dry density and shear strength. Swell potential and swelling pressure decreased with increase in lime content also. Further, consolidation characteristics improved. Compaction characteristics and unconfined compression strength improved at 4%?lime and reduced at 6%?lime. 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.
Effect of Random Inclusion of Polypropylene Fibers on Strength Characteristics of Cohesive Soil 总被引：2，自引：1，他引：1
Pradip Kumar Pradhan Rabindra Kumar Kar Ashutosh Naik 《Geotechnical and Geological Engineering》2012,30(1):15-25
This paper presents the effect of random inclusion of polypropylene fibers on strength characteristics of soil. Locally available
cohesive soil (CL) is used as medium and polypropylene fibers with three aspect ratios (l/d = 75, 100 and 125) are used as reinforcement. Soil is compacted with standard Proctor’s maximum density with low percentage
of reinforcement (0–1% by weight of oven-dried soil). Direct shear tests, unconfined compression tests and CBR tests were
conducted on un-reinforced as well as reinforced soil to investigate the strength characteristics of fiber-reinforced soil.
The test results reveal that the inclusion of randomly distributed polypropylene fibers in soil increases peak and residual
shear strength, unconfined compressive strength and CBR value of soil. It is noticed that the optimum fiber content for achieving
maximum strength is 0.4–0.8% of the weight of oven-dried soil for fiber aspect ratio of 100. 相似文献
5.
垃圾焚烧飞灰水泥固化体强度稳定性研究 总被引：1，自引：0，他引：1
针对垃圾焚烧飞灰安全处置技术要求,采用水泥对其进行固化、稳定化处理,研究了不同水泥添加量、不同养护时间和渗沥液浸泡时间对固化体无侧限抗压强度及破坏特性的影响,并对垃圾渗沥液的侵蚀机制进行了分析。结果表明：当水泥添加量小于5%,养护时间小于3 d时,飞灰固化体在渗沥液浸泡下迅速解体,垃圾渗沥液的侵蚀对飞灰固化体的强度有较大的影响,浸泡后的固化体呈现出明显的应变软化特征,而未经浸泡的固化体的强度增长符合y=a[1-exp(-bt)]模式。随着水泥添加量及养护时间的增加,飞灰固化体无侧限抗压强度增加,破坏应变减小,而随着浸泡时间的增加,飞灰固化体的无侧限抗压强度先增大后减小,转折点大约在5～7 d,破坏应变近似呈线性增大。渗沥液对飞灰固化体的侵蚀主要是其成分抑制了固化体水化反应和破坏了水化产物。研究成果可为垃圾焚烧飞灰的安全处置技术提供理论依据和参数支持。 相似文献
6.
国内每年产生大量的污泥,其无害化处理、废物重新利用的技术是解决疏浚污泥污染问题的必由之路,而污泥固化技术是其重要的途径。纸浆渣烧结灰自身所具有的吸水性和自硬性是一种研制廉价污泥固化剂配方的重要成分,是把造纸产业废弃物和生产废弃物同时再利用的环保工法,具有现实的研究价值。对纸浆渣烧结灰基本特性进行了试验研究,并在此基础上进行了污泥固化的试验研究,主要包括纸浆渣烧结灰酸碱度试验、吸水率试验、微观结构试验、抗剪强度试验和污泥固化土的无侧限抗压强度试验,结果表明,纸浆渣烧结灰呈弱碱性;吸水性随着压力的增大而减小,存在一个最小吸水率;抗剪强度随含水率的增加而减小,且具有自硬性。纸浆渣烧结灰可提高水泥固化污泥的无侧限抗压强度,并且水泥的掺入含量越高,其强度的提高越显著。 相似文献
7.
Daniela Porcino Vito Nicola Ghionna Raffaella Granata Vincenzo Marcianò 《Geomechanics and Geoengineering》2016,11(2):164-175
The purpose of this paper is to investigate mechanical and hydraulic properties of sands treated with mineral-based grouts through the results of a laboratory test programme consisting of unconfined compression tests (UCS), triaxial bender element tests (BeT) and constant flow permeability tests in triaxial apparatus. An improved apparatus was set up for obtaining high quality, multiple grouted specimens from a single column. Two selected natural sands having different grain sizes were grouted with two mineral-based silica grouts, resulting in different levels of improvement. The behaviour of the sands treated by mineral grouts, in terms of strength, initial stiffness and permeability, was compared with that exhibited by more traditional silicate grouts. The results of this study indicate that sands treated with mineral grouts result in higher strengths, higher initial shear modulus and lower permeability values than the sands treated with the silicate solution. The effect of grout type, effective confining pressure, and sand particle-size on small-strain shear modulus of grouted sand specimens was evaluated. Based on test results, the small strain shear modulus increment from treated to untreated specimens has been correlated with the unconfined compressive strength, obtaining a unique relationship regardless of grout type and grain-size of tested sands. 相似文献
8.
The production and utilization of coal is based on well-proven and widely used technologies. Fly ash, a coal combustion byproduct,
has potential to produce a composite material with controlled and superior properties. The major challenges with the production
of fly ash are in its huge land coverage, adverse impact on environment etc. It puts pressure on the available land particularly
in a densely populated country like India. In India the ash utilization percentage has not been very encouraging in spite
of many attempts. Stabilization of fly ash is one of the methods to transfer the waste material into a safe construction material.
This investigation is a step in that direction. This paper presents the results of an investigation on compressive strength
and bearing ratio characteristics of surface coal mine overburden material and fly ash mixes stabilized with lime for coal
mine haul road construction. Tests were performed with different percentages of lime (2, 3, 6 and 9%). The effects of lime
content and curing period on the bearing ratio and tensile strength characteristics of the stabilized overburden and fly ash
mixes are highlighted. Unconfined compressive strength test results cured for 7, 28 and 56 days are presented to develop correlation
between different tensile strengths and unconfined compressive strength. Empirical models are developed to estimate bearing
ratio and tensile strength of mine overburden–fly ash–quick lime mixtures from unconfined compressive strength test results. 相似文献
9.
《Geomechanics and Geoengineering》2013,8(2):141-149
Expansive soils swell on absorbing water and shrink on evaporation thereof. Because of this alternate swelling and shrinkage, civil engineering structures founded in them are severely damaged. For counteracting the problems of expansive soils, different innovative techniques were suggested. Stabilization of expansive clays with various additives has also met with considerable success. This paper presents, by comparison, the effect of lime and fly ash on free swell index (FSI), swell potential, swelling pressure, coefficient of consolidation, compression index, secondary consolidation characteristics and shear strength. Lime content was varied as 0%, 2%, 4%?and 6%?and fly ash content as 0%, 10%?and 20%. A fly ash content of 20%?showed significant reduction in swell potential, swelling pressure, compression index and secondary consolidation characteristics and resulted in increase in maximum dry density and shear strength. Swell potential and swelling pressure decreased with increase in lime content also. Further, consolidation characteristics improved. Compaction characteristics and unconfined compression strength improved at 4%?lime and reduced at 6%?lime. 相似文献
10.
Strength properties of compacted ash layers depend to a great extent on the moulding conditions. This paper focuses on the effects of compaction energy and degree of saturation on strength characteristics of compacted pond ash. The pond ash sample, collected from the ash pond of Rourkela Steel Plant (RSP), was subjected to compactive energies varying from 357 kJ/m3 to 3488 kJ/m3. The optimum moisture content and maximum dry densities corresponding to different compactive energies were determined by conventional compaction tests. The shear strength parameters, unconfined compressive strengths (UCS) and California bearing ratio (CBR) values of specimens compacted to different dry densities and moisture content were assessed and reported. The effects of compaction energy and degree of saturation on shear strength parameters i.e. unit cohesion (cu) and angle of internal friction (Ф) values and also the UCS values are evaluated and presented herein. The results indicate that the dry density and strength of the compacted pond ash can be suitably modified by controlling the compactive energy and moulding moisture content. The strength achieved in the present study is comparable to the good quality, similar graded conventional earth materials. Hence, it may be safely concluded that pond ash can replace the natural earth materials in geotechnical constructions. 相似文献
11.
水泥土中掺入粉煤灰能在一定程度改善其性能,而变形特性是实际工程应用的重要指标。因此,研究粉煤灰和龄期对水泥土变形特性的影响对实际工程具有较大的参考价值。通过粉煤灰掺量为0和8%的水泥土无侧限抗压强度实验,研究发现养护龄期的增长与粉煤灰的掺加有利于水泥土变形模量的增长,尤其是粉煤灰的掺加有利于后期变形模量的增长。进一步对比分析两种粉煤灰掺量时的无侧限抗压强度和平均变形模量,发现它们之间基本上呈线性关系,随后通过拟合得出了它们之间的换算公式。最后,考虑应力-应变曲线模型特征以及对试验数据回归分析,推导出了一定条件下的水泥土应力-应变上升段表达式,为实际工程设计提供参考。 相似文献
12.
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
13.
14.
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
15.
Behavior of expansive soils stabilized with fly ash 总被引：6，自引：0，他引：6
Expansive soils cause serious problem in the civil engineering practice due to swell and shrinkage upon wetting and drying.
Disposal of fly ash, which is an industrial waste in both cost-effective and environment-friendly way receives high attention
in China. In this study, the potential use and the effectiveness of expansive soils stabilization using fly ash and fly ash-lime
as admixtures are evaluated. The test results show that the plasticity index, activity, free swell, swell potential, swelling
pressure, and axial shrinkage percent decreased with an increase in fly ash or fly ash-lime content. With the increase of
the curing time for the treated soil, the swell potential and swelling pressure decreased. Soils immediately treated with
fly ash show no significant change in the unconfined compressive strength. However, after 7 days curing of the fly ash treated
soils, the unconfined compressive strength increased significantly. The relationship between the plasticity index and swell-shrinkage
properties for pre-treated and post-treated soils is discussed. 相似文献
16.
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
17.
Extensive investigations and studies on topography, sedimentary and chronology show new evidence for the formation and evolution
of the Ulan Buh desert during early Holocene. Evidence on clay-sand strata and plant roots under interdune lowlands, lake
shorelines covered by plenty of Corbicula largillierti and large amounts of dry salt lakes in the central region of the desert prove that many megalakes existed in the hinterland
of Ulan Buh desert. Several OSL samples collected from Aeolian sands overlying lacustrine sediments in profiles around Jilantai
Salt Lake and interdune lowlands in the southern Ulan Buh desert suggest that the desert began around 7 ka B.P.. The formation
of Ulan Buh desert may have resulted from the shrinking of Jilantai megalakes and sands blown from exposed loose sediments.
__________
Translated from Journal of Desert Research, 2007, 27(6): 927–931 [译自: 中国沙漠] 相似文献
18.
为探究赤泥改性黄土的基本工程特性,进行无侧限抗压试验、直剪试验及渗透试验,得出赤泥改性黄土的最佳配比,建立了抗剪强度、无侧限抗压强度与电阻率的经验公式。通过动三轴试验,分析了循环动荷载下改性黄土的累积塑性变形、动弹性模量及浸出毒性。结果表明,随赤泥含量增加,改性黄土无侧限抗压强度和黏聚力都先增大后减小,当赤泥含量为15%时其28 d无侧限抗压强度达到3.5 MPa,较不掺入赤泥时提高约34.7%;改性黄土的渗透系数随赤泥含量增加先快速降低,至赤泥含量5%后趋于稳定;改性黄土的抗剪强度、无侧限抗压强度与电阻率呈良好的线性关系;改性黄土在循环动荷载下的临界动应力达600 kPa,最大动弹性模量比未改性黄土高出6倍,且其浸出液不具有浸出毒性。 相似文献
19.
盐渍土化学固化法是解决盐渍土盐胀、溶陷和腐蚀等不良工程问题的有效方法之一。通过无侧限抗压强度试验、X射线衍射试验、化学成分分析和扫描电镜试验研究了石灰粉、煤灰、水玻璃联合固化硫酸盐渍土的强度特征,分析探讨了其固化机制。试验结果表明：石灰含量小于8%时,石灰、粉煤灰、水玻璃联合固化硫酸盐渍土的抗压和抗剪强度较石灰粉煤灰固化土有大幅度提升,固化土强度随水玻璃浓度几乎呈线性增长。水玻璃固化硫酸盐渍土强度增加的机制在于：水玻璃的碱激发粉煤灰作用和水玻璃与盐渍土中化学成分的吸附作用所生成各类凝胶的填充和包裹,使得骨架颗粒的接触面积增大,颗粒之间的孔隙逐步减小,骨架颗粒由点接触变为面接触,固化盐渍土通过凝胶而黏结成为一个紧密的空间网状整体结构,土体强度得以提高。同时,复杂的物理化学作用大幅度降低了固化盐渍土中 含量,有效地抑制了硫酸盐渍土的盐胀特性。 相似文献
20.
结构性软土力学特性试验研究 总被引：3，自引：0，他引：3
选取广州南沙典型软土为研究对象,进行了剪切、无侧限抗压、固结等室内试验.从强度和变形两方面对试样的结构性进行了研究,分析了原状土和重塑土的变形特性、强度特性和固结特性,揭示了所研究的区域性软土的结构性特征以及这一特征对软土工程性质的影响.试验结果表明:结构性软士经扰动后强度明显降低,压缩性增加;原状土的同结特性与结构屈服压力有关,压缩曲线呈现3阶段特征.在同一级荷载下扰动后的土体变形规律较原状土有更明显的主次固结划分界限.结构屈服压力是变形规律的控制因素之一,可以通过压缩系数-固结压力曲线近似确定.试验结果还表明,当崮结压力较大时,原状土的结构被完伞破坏,此时结构性对土体力学特性的影响可被削弱,甚至消失. 相似文献