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通过级配分析、击实试验，分析了含砂低液限粉土的物理力学特性和压实特性。认为现行以压实度为指标的压实控制标准的不完备，是引起公路病害的主要原因之一。为了解决这一问题，引入空气体积率作为粉土压实的辅助控制标准，并建议提高现行路堤的压实度控制标准。 相似文献
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强夯法加固岷江防洪堤粉土地基的效果检验 总被引：4，自引：1，他引：3
对宜宾市岷江防洪堤工程粉土地基进行了强夯法加固现场试验,介绍了试验区强夯法的施工设计和现场检测与室内试验结果。强夯法加固地基现场检测结果表明,采用1 600 kN?m的夯击能使该粉土地基有效加固深度达到8 m。 当夯点间距为5 m,强夯2遍,满夯1遍后,现场检测和取土实验结果表明：由于强夯作用,粉土层的干密度明显增加,压缩性和渗透性降低。在天然地基中,32.2 %的标准贯入击数小于5,强夯以后,标准贯入击数全部大于7。粉土地基经过强夯处理后,满足了防洪堤地基对承载力和渗透性的要求,消除了Ⅶ度地震液化势。采用正三角形夯点布置区的加固效果明显优于正方形夯点布置区的加固效果。 相似文献
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文中通过级配分析、击实试验,分析了高液限粘土路基填土的物理力学特性和压实特性。认为现行以压实度为指标的压实控制标准不完备,是引起公路病害的主要原因之一。建议引入空气体积率作为粘土路基压实程度的评判标准,并提高现有压实度控制标准中路堤的压实度。 相似文献
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M. D. Gidigasu 《Geotechnical and Geological Engineering》1991,9(3-4):219-260
Summary Road transportation is increasingly becoming one of the key factors for promoting economic growth in most developing countries. However, transport and road research in the tropics has received relatively little attention. Experiences in road construction in the tropics within the past 50 years or so have established that local materials specifications and pavement construction technologies have to be developed in relation to the climatic conditions. This would involve knowledge of the processes of formation as well as genetic characteristics of the local gravels. Genetic characteristics exert considerable influence on the geotechnical properties and engineering behaviour of local gravels under pavement. The construction technology of the road pavement should take cognizance of the compositional variabilities of the gravel deposits. Construction studies of pavement sections (as well as assessment of the performance of existing roads) built with different gravels formed over different geological formations in specific climatic, and drainage conditions would provide useful data for evolving local gravel specifications for constructing stable and durable pavements. Stage construction of pavements involving the exposure of the various layers to traffic loading and seasonal climatic influences appears to hold promise for formulating strategies for constructing stable, and long-term durable tropical roads. The problem of achieving reproducible laboratory test data under field conditions is perhaps the most challenging aspect of utilizing local gravels for pavement construction in tropical and sub-tropical conditions. It is noted that the stability of pavements in tropical environments depends not so much on the geotechnical properties of the available gravels as on the appreciation by the designers and construction engineers of the relationship between the genetic and laboratory determined characteristics of the gravels on the one hand and the pavement construction technology and local climatic and drainage conditions on the other. This paper is a contribution to development of highway geotechnics for tropical and sub-tropical conditions. 相似文献
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C. M. O. Nwaiwu I. B. K. Alkali U. A. Ahmed 《Geotechnical and Geological Engineering》2006,24(2):283-298
A laboratory investigation was conducted to determine properties of five samples of ‘oolitic ironstone’ lateritic gravel aggregates
which are relevant to their use as road construction materials. Measured values of physico-chemical, physico-mechanical as
well as index properties and compaction characteristics are similar to those of other lateritic, gravels occurring in West
Africa which are used in road pavement applications. These lateritic clayey gravels have good workability as engineering construction
materials and are rated fair to good as road aggregates in terms of probable in-situ behaviour based on water absorption values. Relationships between maximum dry unit weight and optimum moisture content as
well as those between California bearing ratio and some derived soil parameters such as grading modulus, plasticity product
or plasticity modulus can be described using a third-order polynomial function. The maximum dry unit weight has a bimodal
frequency distribution and can be predicted from logarithm to base 10 of compaction energy with fairly good accuracy. 相似文献
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压实黄土回弹模量试验研究 总被引：2，自引：0，他引：2
土基回弹模量是路面结构设计中一个非常重要的参数,直接关系到路面结构的安全性和经济性。室内振动压实是室内击实成型试件的一种新方法,能较好地模拟振动压实的特点。研究了压实黄土回弹模量与其干密度、含水率、稠度和压实度以及龄期等物理指标之间的关系,并分析了振动压实黄土的回弹模量与击实黄土的回弹摸量。研究结果表明,压实黄土的回弹模量与其干密度、含水率、稠度和压实度以及龄期之间有一定的相关关系。在推荐参数条件下,室内振动压实黄土回弹模量比室内击实的要大。 相似文献
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《城镇道路工程施工与质量验收规范》（CJJ1—2008）颁布实施快一周年了,在执行过程中,作者认为规范条文中压实系数的概念难于理解、路基压实度指标偏低,石灰、粉煤灰稳定碎石中集料级配选择余地较小等,并对此提出修编建议。 相似文献
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在湿陷性黄土地区,黄土作为高速公路地基的主要原料其强度和变形特性不能满足要求,主要有振动碾压、冲击碾压和强夯3种有效且实用的处治方法。本文根据原位试验和室内试验的数据,进行有限元模拟,在不同高度路堤和不同加载方式情况下,地基沉降变形随着处治能级的增加而减小,路堤本身的沉降保持不变。对于地基处理的深度和沉降变形减小的效果,强夯最好,冲碾次之,振碾最弱。处治前后地表中心沉降变形值与加载路堤高度之间的关系均可用二阶多项式回归拟合。2～4m高的路堤采用振碾的方式处理地基,5～10m高的路堤采用冲碾方法,大于10m的路堤多用强夯或者直接修桥来代替,对于黄土地区高速公路建设与维护具有重要意义。 相似文献
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Magnus Wangen 《国际地质力学数值与分析法杂志》1997,21(2):91-120
The upstream-weighted finite element method with lumped mass matrix is applied to the modelling of oil migration in compacting sedimentary basins. An implicit formulation is made in Lagrangian co-ordinates of a pressure, saturation and a temperature equation, which is based on immiscible two-phase flow of oil and water. The formulation accounts for the compaction of the sediments, the generation of oil from solid organic material (kerogen), the eventual pore space generated by kerogen breakdown, and the density variations of the fluids which may set up thermal convection. The model is validated by comparison with results from a one-dimensional (1D) fractional flow-based migration model. A 2D case example showing oil expulsion from source rocks, and the filling of a trap is presented. The mass balance of the model is easily checked because all oil in the basin originates from breakdown of kerogen. Compared with other alternatives, the simple upstream-weighted finite element method is suggested as a possible first choice for a numerical method for the modelling of oil migration in compacting sedimentary basins. It easily deals with the complex geometry of a basin, it yields reasonably good results, is simple to implement, and the same implementation applies to all spatial dimensions. © 1997 by John Wiley & Sons, Ltd. 相似文献
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黄土的湿陷性对于建筑的安全具有极大的危害性,而强夯法可以有效地消除黄土的湿陷性。通过对强夯前后湿陷性黄土的物理力学性质及微观结构进行对比分析,强夯效果沿深度可分为三段,从3 m至8 m为强夯效果最佳段。强夯使土体中孔径大于20 μm的孔隙含量减少,小于5 μm的孔隙含量增加,土体的致密程度提高。 相似文献
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土石混填路基修筑技术研究综述 总被引：21，自引：3，他引：21
土石混合料作为一种填料，越来越广泛地被应用于工程实践，尤其是公路路基工程中．国内外学者对土石混合料的物理力学性质、压实特性和土石混合路基修筑技术已进行了大量的研究，但由于这些研究尚处于初级阶段，因而，仍不能满足工程实践的需要。笔者对不同石质类型、不同比例土石混合料的物理力学性质，土石混合料的分类、工程分级和性能评价，土石混填路基的均匀性及其强度与变形规律，土石混填路基的设计理论和设计方法，土石混填路基施工工艺及质量控制方法等方面进行深入系统的分析。提出了目前研究存在的问题及其解决的初步方法。 相似文献
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Henry Grace 《Geotechnical and Geological Engineering》1991,9(3-4):183-195
Summary In Kenya 1974/5 and in Malawi 1984/5 trial sections of bituminous-surfaced low volume roads were constructed using as-dug laterite in place of stone or stabilized material as a base course.The laterite did not conform with any accepted specifications but performed equally well when compared with adjoining sections of road using stone or stabilized material as a base.The construction procedures employed are described. A period of 4–6 weeks between the compaction of the base and its surfacing is considered essential if the road is to perform satisfactorily. During this period it is exposed to the weather and traffic or to periodic watering and rolling. This treatment fills any cracks with dust or mud and closes them by the kneading action of rubber-tyred traffic. The bituminous surfacing is applied where the base has dried out to about half the optimum moisture content and is extended about 1.5 m beyond each edge of the carriageway.In 1984, $40000 US per km was saved in Malawi in this way, approximately 70% being in convertible currency without incurring additional maintenance or vehicle operating costs. 相似文献
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黏土单层击实试验与制样因子研究 总被引：1，自引：1，他引：0
使用非标准击实仪进行单层击样,获取非标准击实状态下单层击实样的密度与击实功及含水率之间的关系,并进一步以得到的击实样获得其抗剪强度。发现当击实功小到一定程度时,击实密度随含水率的增大而不断增大,两者近似线性变化,无峰值出现。密度峰值对应的含水率与抗剪强度峰值对应的含水率有一个差值,其值在3.4%～5.7%之间。内摩擦角随含水率增大而减小的规律仅适合于一定的击实功。内摩擦角在较小的击实功下有峰值出现,但随着击实功的增大,内摩擦角的变化呈线性而非曲线形式。另外,针对土工室内模型试验的重塑土样制备问题,结合试验数据,给出了试验最优制样参数,并初步提供了评价指标?。 相似文献
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开展饱和钙质砂爆炸密实动力特性试验研究,探索饱和钙质砂爆炸密实机制和密实效果,对钙质砂地层中进行的工程建设有重要的理论意义和工程实用价值。通过控制爆炸参数,测试不同参数作用时钙质砂爆炸前后声波特性和表面沉降规律,揭示饱和钙质砂爆炸密实动力特性。试验结果表明：钙质砂高孔隙比和颗粒破碎特性对爆炸密实效果有重要影响。爆炸密实作用后,在爆炸近区,钙质砂颗粒受到较强爆炸冲击作用,导致钙质砂颗粒破碎而形成破碎区和压缩区,压缩区随着时间的推移有松弛的趋势,钙质砂颗粒结构重新固结过程在爆炸后2 h内基本完成。 相似文献
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在国内现行的各类土工试验规程中,5点击实法是最基本的土工击实试验方法,具有用土量大、费时、费力,而且试验数据处理麻烦等缺陷。为了克服这些缺陷,采用静压脱湿试验法,对人工配制含水率,而且含水率高于该土的塑限含水率的不同土样进行脱湿。试验结果表明：各土样脱湿后的含水率具有稳定在标准击实功下该土最优含水率以下某一稳定水平的特点。由此提出：可将需要击实的土样先脱湿,得出土样脱湿后的含水率,再乘以有关系数求得土的最优含水率,直接对最优含水率下的土体进行标准击实功单点击实,从而快速准确地获得该土的最优含水率和最大干密度。通过对比试验验证,单点击实法不但简单、快速,而且具有足够的可靠性。 相似文献
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三江平原沼泽湿地区,在自然和人为影响下,发育着五种不同类型的道路翻浆,某些路段产生雪阻,冰糊(涎流冰)、路面挂冰等道路冻害,严重影响交通运输,采取相应防治措施维持运营。 相似文献
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由于煤矿再生岩体围岩结构和成分进行了重组,其力学特性将发生本质变化。根据再生岩体压实成岩过程中破碎岩体多次受压的实际情况,采用广西州景煤矿再生顶板破碎围岩进行有侧限条件的分次压实试验。结果表明:分次压缩过程可分为压实破碎、压实应力记忆和压密固结3个阶段。在第1次压缩时,压实特性曲线呈线性变化,后续压实特性曲线逐渐向指数形式转变,而"压实应力记忆"阶段表现为多项式变化。在侧限压缩条件下,提出以最小势能原理作为判定不规则岩样挤压破碎判据。破碎岩样压缩特性受压实次数和装岩高度的影响,破碎岩样分次压实次数越多,累积压缩应变越大,后续压缩时的应力增量越大。装岩高度越大,压缩至相同压应力时,累积总应变越大。压实应力达到一定程度,不同粗粒径破碎岩样的粒径分布规律趋于一致,据此建立了破碎岩样粒径分布与工程中破碎岩体压实程度之间的相关关系。 相似文献