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Investigation of bottom ash as a partial replacement to conventional subbase soils 底灰部分替代常规底基土的研究
Q2 Engineering Pub Date : 2023-09-01 DOI: 10.1680/jgrim.21.00038
Thet Htet Ye Htun, Parnthep Julnipitawong, Weeraya Chimoye, Somnuk Tangtermsirikul
This study evaluates the potential use of bottom ash (BA) in the subbase layer of pavements. Lateritic soil, a conventional subbase soil, was mixed with 0–60% of BA, and their properties were studied. The lateritic soil was sieved into grade B and grade D soils. Each grade of soil is mixed with BA at varying content and their bearing capacity and permeability properties were tested. The California bearing ratio (CBR) samples were compacted at optimum water content (OWC) and OWC + 2%. At OWC, both grades of soil showed a high CBR when 30–60% BA was mixed. However, when the samples were compacted at OWC + 2%, CBR values reduced drastically and only a few mixtures passed the minimum CBR requirement for subbases by the Department of Highway, Thailand. To explain the mechanism behind the CBR trends, the gradation of the mixtures before and after CBR was checked and interaction compaction effects were observed. This phenomenon was further proved by the results of permeability.
本研究评价了底灰(BA)在路面亚基层中的潜在用途。以红土土为基土,掺入0 ~ 60% BA,对其性质进行了研究。红土分为B级和D级土。在不同等级的土中掺入不同含量的BA,测试其承载力和渗透性能。在最佳含水率(OWC)和OWC + 2%的条件下对CBR样品进行了压实。在最低含水率下,30 ~ 60% BA混合时,两级土壤的CBR均较高。然而,当样品在OWC + 2%压实时,CBR值急剧下降,只有少数混合物通过了泰国公路部门对基层的最低CBR要求。为了解释CBR趋势背后的机制,检查了CBR前后混合物的级配,并观察了相互作用的压实效果。渗透率的结果进一步证明了这一现象。
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引用次数: 1
Assessment of alkali-induced heave in soil and its stabilisation using slag 土中碱致隆起评价及矿渣稳定
Q2 Engineering Pub Date : 2023-09-01 DOI: 10.1680/jgrim.21.00019
Manish Kumar Mandal, Bala Ramudu Paramkusam
Soil–alkali-interaction results in unexpected heaving and other negative effects of soil properties, which can lead to complete failure of structures. An investigation was carried out on the impact of highly concentrated sodium hydroxide alkali on the heaving behaviour of low-plasticity clay. The effect of ground-granulated blast-furnace slag as a stabiliser for alkali-interacted soil was also investigated. The interaction of alkali with the soil showed heaving up to 5.25% after 30 days, while a slag content of 20% showed maximum suppression of heave. The alkali-interacted soil stabilised with slag was also compared with un-interacted soil mixed with slag. There was a marginal increase in friction angle with an increase in curing period, and a significant increase in cohesion for both. A substantial improvement in unconfined compressive strength was also evident with increased slag content and curing period. The results were supported by microstructural examinations. The application of slag as a liquid-based stabiliser for alkali-interacted soil was also conducted using electrokinetics. Statistical analysis indicated that the curing period was a dominant parameter in affecting the compressive strength of un-interacted soil while, for alkali-interacted soil, slag content was more dominant.
土-碱相互作用会导致土体发生意想不到的起伏和其他负面影响,从而导致结构的完全破坏。研究了高浓度氢氧化钠碱对低塑性粘土起伏特性的影响。研究了高炉磨粒渣作为碱作用土的稳定剂的效果。碱与土壤的相互作用使30 d后的沉陷率达到5.25%,而矿渣含量为20%时对沉陷的抑制作用最大。并对碱相互作用后的矿渣稳定土与碱相互作用后的矿渣稳定土进行了比较。随着养护时间的延长,摩擦角略有增加,黏聚力均有显著增加。随着渣量的增加和养护时间的延长,无侧限抗压强度也有了明显的提高。结果得到了显微组织检查的支持。利用电动力学方法对矿渣作为液基稳定剂在碱作用土壤中的应用进行了研究。统计分析表明,养护时间是影响未相互作用土抗压强度的主要参数,而对于碱相互作用土,矿渣含量的影响更大。
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引用次数: 1
Effect of surcharge loads during curing of lime stabilised Cochin marine clay 石灰稳定科钦海相粘土固化过程中附加荷载的影响
IF 1.2 Q2 Engineering Pub Date : 2023-08-23 DOI: 10.1680/jgrim.22.00051
Rija Johny, B. M. Abraham, A. Sridharan
The marine clays possess poor engineering properties and need to be improved prior to any construction activities on them. Lime stabilization is a widely adopted method of chemical stabilization for such types of soils. This paper evaluates the effect of surcharge loads during curing of lime stabilization of Cochin marine clays. In the case of lime-stabilized soil cured under surcharge loads, it is necessary to consider two processes, i.e. cementation and consolidation, along which the structures of stabilized soils evolve. These two processes are interrelated and cannot be considered separately, especially in the early stages of curing when significant structural changes occur. This study investigated the strength and deformation characteristics of lime stabilized Cochin marine clay subjected to surcharge loading during curing. The marine clay with 6% lime was subjected to surcharge loads of 20kPa, 40kPa, and 60kPa for different curing periods up to 180 days. The effect of surcharge loading on shear strength and compressibility characteristics were evaluated at different curing periods.
海相粘土具有较差的工程性能,在进行施工前需要对其进行改良。石灰稳定是这类土壤广泛采用的化学稳定方法。本文对科钦海相粘土石灰稳定养护过程中附加荷载的影响进行了评价。对于石灰稳定土在附加荷载作用下的固化,需要考虑两个过程,即胶结和固结,稳定土的结构沿着这两个过程演变。这两个过程是相互关联的,不能分开考虑,特别是在固化的早期阶段,当发生重大的结构变化时。研究了石灰稳定科钦海相粘土在附加荷载作用下的强度和变形特性。对含6%石灰的海相粘土分别施加20kPa、40kPa、60kPa的附加荷载,养护时间长达180天。研究了不同龄期附加荷载对混凝土抗剪强度和压缩性的影响。
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引用次数: 0
Effect of smear zone on the consolidation and strength characteristics of soil under radial drainage 涂抹带对径向排水条件下土体固结及强度特性的影响
IF 1.2 Q2 Engineering Pub Date : 2023-08-18 DOI: 10.1680/jgrim.21.00040
R. Aparna, R. Robinson, S. R. Gandhi
Vertical drains installed in soft clay deposits enhance the rate of consolidation in preloading projects. Using a mandrel to install the prefabricated vertical drains (PVD), its insertion and withdrawal will result in the remoulding of the soil zone surrounding it, called the smear zone. The extent of the smear zone is an important parameter that characterizes the smearing effect. This paper describes this effect in terms of smear ratio (i.e., the ratio of the diameter of smear zone ds to the diameter of drain, dw) on the consolidation characteristics of soil with radial drainage. A series of radial consolidation tests with a predetermined smear zone in a model unit cell was conducted by varying the diameter of the smear zone. The experimental results show that beyond a smear ratio of 4, the soil behaves as if it is in a fully remoulded condition. The results were compared with some of the theoretical approaches reported in the literature. The analytical solution that predicts the time-settlement curve in a better way is identified. Also, it is observed that the gain in undrained shear strength due to the consolidation of soft clay decreases with the increase in the diameter of the smear.
在软粘土沉积物中安装垂直排水管,可提高预压工程的固结速度。使用芯轴安装预制垂直排水管(PVD),其插入和取出将导致周围土壤区域的重塑,称为涂抹区。涂抹区域的范围是表征涂抹效果的一个重要参数。本文从涂抹比(即涂抹区直径ds与排水管直径dw之比)对径向排水土固结特性的影响来描述这种影响。通过改变涂抹区域的直径,在模型单元格中进行了一系列具有预定涂抹区域的径向固结试验。实验结果表明,当涂布比大于4时,土壤表现为完全重塑状态。结果与文献中报道的一些理论方法进行了比较。确定了较好地预测时间沉降曲线的解析解。此外,还观察到由于软粘土固结而获得的不排水抗剪强度随涂布直径的增加而减小。
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引用次数: 0
Effect of tyre crumbs on the stability of sand under constant shear drained stress 恒定剪切排水应力下轮胎碎屑对砂土稳定性的影响
IF 1.2 Q2 Engineering Pub Date : 2023-05-10 DOI: 10.1680/jgrim.22.00085
Shabir Ahmed, J. Vinod, M. Sheikh
The instability of earth structures resting on granular materials, such as embankments and tailing dams, is caused by the infiltration of water which can lead to their failure. This paper presents the potential use of tyre crumbs for controlling the stability of structures made of sand. Constant shear drained experiments were carried out on mixtures of sand and tyre crumbs to understand the onset of instability. Conventional drained shear tests were carried out on all samples up to a deviator stress of 200 kPa. Tests were then carried out on the sheared samples by reducing the confining pressure until the onset of instability. This was determined by a drop in stress, by second-order work and by the strain ratio approach. The value of mean effective stress at instability was found to decrease with the addition of tyre crumbs to the mix of up to 20% and then increase with further addition of tyre crumbs. The strain ratio approach was found to predict the onset of instability easily and efficiently, similar to the second-order work method.
基于颗粒材料的土质结构的失稳,如堤防和尾矿坝,是由水的渗透引起的,水的渗透会导致土质结构的破坏。本文介绍了轮胎碎屑在控制砂土结构稳定性方面的潜在用途。采用恒剪切排水试验对砂土和轮胎碎屑的混合物进行了试验,以了解其失稳的发生。对所有试样进行常规排水剪切试验,直至偏差应力为200 kPa。然后通过降低围压对剪切试样进行试验,直到失稳开始。这是由应力下降、二阶功和应变比法确定的。不稳定时的平均有效应力值随着掺量达到20%而减小,然后随着掺量的增加而增大。结果表明,应变比法与二阶功法相似,能方便、有效地预测失稳的发生。
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引用次数: 0
Influence of type of drainage boundary on coefficient of horizontal consolidation 排水边界类型对水平固结系数的影响
IF 1.2 Q2 Engineering Pub Date : 2023-04-20 DOI: 10.1680/jgrim.22.00055
G. Sridhar, R. Robinson, K. Rajagopal
Vertical drains are used widely to accelerate the consolidation of soft clay deposits when preloading is used as a ground improvement technique. One of the essential input parameters required in Barron's theory is the coefficient of horizontal consolidation, ch. The values of ch can be determined by the radial consolidation test, using either a central sand drain or a porous plastic peripheral drain. This paper presents the laboratory tests carried out to understand the reason for the difference in values of ch determined from inward and outward radial flow consolidations tests. A 150 mm diameter instrumented consolidation cell was used to perform the inward or outward radial consolidation tests. The total stress measurements during consolidation showed non-uniform stress distribution in clay with higher effective stress values close to the drainage boundary. This stiffening of the clay close to the drain retards the consolidation rate resulting in reduced values of ch. As a result, the ch values determined by radially outward consolidation tests with larger drainage boundary area are lower to those obtained by the inward radial flow test. The pore water pressure measurements showed significantly higher undissipated pore water pressure away from the drainage boundary for the outward flow test.
在采用预压地基加固技术时,垂直排水管被广泛用于加速软粘土沉积的固结。巴伦理论要求的一个重要输入参数是水平固结系数ch。ch的值可以通过径向固结试验确定,使用中心砂土排水或多孔塑料外围排水。本文介绍了为了解从向内和向外径向流固结试验中测定的ch值不同的原因而进行的实验室试验。采用直径150mm的仪器固结箱进行向内或向外径向固结试验。固结过程中总应力测量结果表明,粘土中应力分布不均匀,靠近排水边界处有效应力值较高。靠近排水口的粘土的这种硬化延缓了固结速率,导致ch值降低。因此,在较大的排水边界面积下,径向向外固结试验得到的ch值低于向内径向流动试验得到的ch值。孔隙水压力测量表明,在远离排水边界的地方,向外流动试验的未耗散孔隙水压力明显更高。
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引用次数: 0
Permeation grouting in soils: numerical discussion of the reliability of a simplifying analytical approach 土中渗透注浆:一种简化解析方法可靠性的数值讨论
IF 1.2 Q2 Engineering Pub Date : 2023-04-03 DOI: 10.1680/jgrim.22.00019
K. Boschi, D. Grassi, R. Castellanza, C. G. di Prisco
Permeation grouting, i.e. injections at low pressure values of either microfine cements or chemical products, is frequently adopted to increase the mechanical/hydraulic properties of soils and standard design approaches are currently either empirical or based on simplified analytical solutions. In this paper, some fundamental hypotheses of these analytical solutions are discussed by performing a campaign of finite element numerical analyses, in which the injection phase in a water saturated soil is analysed, a Newtonian rheology for the grout is implemented and the hypothesis of immiscibility for the two liquids is assumed. The injection source geometry effect is discussed, as well as the role of gravity and capillarity. The authors analyse the conditions, in terms of injection flow rate, grout viscosity, soil intrinsic permeability and retention curve, under which the analytical solutions provide reliable results. The numerical results have been compared with the simplified analytical solution herein derived for a 1D spherical geometry, in terms of the “characteristic curves” for the system: the relationship between injection pressure/grout front advancement and injection time.
渗透注浆,即在低压值注入微细水泥或化学产品,经常被用来增加土壤的力学/水力特性,目前的标准设计方法要么是经验的,要么是基于简化的解析解。本文通过进行一系列有限元数值分析,讨论了这些解析解的一些基本假设,其中分析了饱和水土壤中的注入阶段,实现了浆液的牛顿流变性,并假设了两种液体的不混相。讨论了注入源的几何效应,以及重力和毛细作用。从注浆流量、浆液黏度、土体固有渗透性和截留曲线等方面对不同条件进行了分析,得到了可靠的结果。数值计算结果与一维球面几何简化解析解进行了比较,得到了注浆压力/注浆前缘推进与注浆时间之间的特征曲线。
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引用次数: 1
Evaluating improved moduli of geogrid-stabilised sandy soil with a deflectometer 用偏转计评价土工格栅稳定砂土的改进模量
IF 1.2 Q2 Engineering Pub Date : 2023-03-30 DOI: 10.1680/jgrim.22.00075
Sidhu Ramulu Duddu, Vamsi Kommanamanchi, Hariprasad Chennarapu, U. Balunaini
Geogrid-stabilised soil has been widely adopted to enhance performance in transportation and infrastructure sectors. In a study, the performance of unstabilised and triaxial-geogrid-stabilised sandy soils in terms of dynamic deformation modulus and elastic modulus was measured using lightweight deflectometer test and plate load tests respectively. The objective of the study was to evaluate: (a) determination of dynamic deformation modulus of sandy soils with different relative compactions from deflectometer testing and compare with the elastic modulus of sandy soils from plate load tests for a given relative compaction of 97%; (b) determination of modulus improvement factors of triaxial-geogrid-stabilised sandy soils through extensive laboratory testing; and (c) demonstration of compaction quality control of well-graded gravel using deflectometer testing through a field study. The triaxial-geogrid-stabilised sandy soil layer showed modulus improvement factors of 1.51 and 1.37 obtained from deflectometer and plate tests corresponding to an embedded depth of 50 mm respectively. The percentage differences in these values are in the range of 4% to 9% for all the embedded depths. Hence a lightweight deflectometer can be used instead of a plate load test as a quick and low-cost alternative for determining the modulus improvement factor of geogrid-stabilised sand soil, both in the laboratory and in the field.
土工格栅稳定土已被广泛采用,以提高交通和基础设施部门的性能。在一项研究中,不稳定和三轴土工格栅稳定的沙土在动态变形模量和弹性模量方面的性能分别采用轻型偏转仪试验和板荷载试验进行了测量。本研究的目的是评估:(a)从偏转计测试中确定不同相对压实度的沙土的动态变形模量,并与给定相对压实度为97%的板载试验中沙土的弹性模量进行比较;(b)通过广泛的实验室测试,确定三轴土工格栅稳定砂质土的模量改善系数;(c)通过现场试验,论证了用偏转仪对分级良好的砾石进行压实质量控制。三轴土工格栅稳定沙土层的模量改善系数分别为1.51和1.37,分别对应于埋深为50 mm的偏转仪和板试验。对于所有嵌入深度,这些值的百分比差异在4%到9%之间。因此,无论是在实验室还是在现场,轻质挠度计都可以代替板荷载测试,作为确定土工格栅稳定砂土的模量改善系数的快速和低成本替代方案。
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引用次数: 0
Mechanical behavior of grouted sands with acrylates and polyurethane resins 丙烯酸酯和聚氨酯树脂灌浆砂的力学性能
IF 1.2 Q2 Engineering Pub Date : 2023-03-30 DOI: 10.1680/jgrim.23.00005
G. Spagnoli, S. Collico, Götz Tintelnot
Chemical grouting is a technique where solution-based binders are used to improve both mechanical and hydraulic properties of the soils or rocks. The following research shows an extensive laboratory program where a polyurethane and an acrylate were grouted in a tertiary sand under different water contents, relative density, with different gelling time and different grouting conditions. Unconfined compressive strength (UCS), splitting tests, triaxial tests and creep tests on the grouted materials were performed. A statistical interpretation considering the Kernel probability density function was performed in order to understand the interdependency of the changing parameters. In general polyurethane-consolidated samples provide higher mechanical properties with respect to acrylates, however the effects and the dependency to the geotechnical base parameters are different.
化学灌浆是一种使用溶液基粘合剂来改善土壤或岩石的机械和水力特性的技术。在不同含水量、相对密度、不同胶凝时间和不同注浆条件下,对聚氨酯和丙烯酸酯在三级砂中进行了大量的实验研究。对注浆材料进行了无侧限抗压强度试验、劈裂试验、三轴试验和蠕变试验。为了理解参数变化的相互依赖性,采用核概率密度函数进行了统计解释。一般来说,聚氨酯固结样品相对于丙烯酸酯具有更高的力学性能,但是对岩土基础参数的影响和依赖是不同的。
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引用次数: 1
Award-winning paper in 2021 2021年获奖论文
Q2 Engineering Pub Date : 2023-03-01 DOI: 10.1680/jgrim.2023.176.1.66
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引用次数: 0
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Proceedings of the Institution of Civil Engineers-Ground Improvement
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