共查询到17条相似文献，搜索用时 234 毫秒
1.
风积沙路基的处理一直是沙漠公路建设面临的难题, 土工格室加固方法可为沙漠公路建设提供一条新路径, 结合S21线(乌鲁木齐-阿勒泰)沙漠公路路基现场试验, 研究不同路基深度动力响应特征, 对土工格室加固风积沙性能探究具有重要的价值及意义。结果表明: ①测试车速对路基不同深度处动应力、动加速度和动速度的时程曲线波动性影响较大, 且提高车速时, 动速度峰值、动加速度峰值和动应力峰值都出现了明显的增加; ②随着路基层深度的不断增加, 动速度幅值、动加速度幅值和动应力幅值均呈现出逐渐衰减的趋势, 其中在土工格室加固风积沙层衰减幅度最大; ③沿路基横断面水平方向上, 动速度幅值、动加速度幅值和动应力幅值均呈指数型衰减的趋势, 距振动源水平距离为5 m时, 其幅值衰减至10%左右, 可将此水平范围作为工程设计参考值。 相似文献
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为了分析冻土地基中输电线路基础发生冻拔破坏的科学问题, 以锥管板条装配式基础为研究对象, 采用室内模型试验测试及分析的研究方法, 开展了不同环境温度下, 冻土地基的冻结试验和基础的上拔加载试验, 分析了地基温度场、位移场的分布特征以及基础抗拔承载力与温度之间的关系, 揭示出上拔荷载作用下冻土地基的破坏模式。研究结果表明: 冻结试验中, 模型基础的冻拔位移均小于周围地基土体的冻胀位移, 基础对地基土体的冻胀存在反约束作用, 距离基础越近, 约束作用越明显; 不同冻结环境温度下基础的上拔加载试验中, 抗拔极限承载力均随环境温度的降低近似呈线性增大, 增加速率接近1.8 kN/℃; 在冻结与上拔力双重作用下, 地基土体首先出现局部张拉破坏, 随着上拔荷载的不断增加, 地基土体逐渐由局部张拉破坏过渡为整体剪切破坏。研究成果可为这种形式的基础在冻土地基中的应用提供理论依据和实践经验。 相似文献
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江汉油田废弃油基钻井液处理 总被引：1，自引：0，他引：1
根据江汉油田废弃油基钻井液特点,采用化学破乳法处理该废弃油基钻井液,在废弃油基钻井液中加入破乳剂、絮凝剂和混凝剂.结果表明:油回收率达到94.2%,芬顿氧化处理后的废水达到《污水综合排放标准》(GB 8978—1996)二级标准,COD去除率达到97.35%,色度去除率达到95.83%;经过固化剂固化96h后,泥渣固化物紧密度达到Ⅳ级,固化物浸出液达到《污水综合排放标准》(GB 8978—1996)二级标准,能够实现江汉油田废弃油基钻井液无害化处理. 相似文献
4.
为研究盱眙黏土团粒大小对改良填料水稳性的影响，结合苏北某高速公路工程实际，对不同团粒粒径的石灰土、新型固化土的8组试样进行了加州承载比试验。结果表明：石灰土、新型固化土的膨胀量、吸水量随团粒粒径的增大表现为先减小后增大的趋势，而加州承载比值随团粒粒径的增大则表现为先增大后减小的趋势。同时，对比两种改良方法，新型固化剂的整体改良效果好于灰土，且在较大的团粒粒径处达加州承载比最大值，同时填料水稳性受团粒粒径影响不及灰土大。在以上试验结果的基础上，就盱眙黏土的团粒大小对填料水稳性的影响机理进行了分析和讨论。 相似文献
5.
针对季冻区春融期岩锚失效的问题, 研究了玻璃纤维(GFRP)锚杆在冻融循环作用下的锚固能力。通过设计物理模型对经历25, 50, 75冻融周期的试块进行了加载试验, 根据试验数据和破坏现象分析了GFRP锚杆在冻融后锚杆应力和承载力的变化规律。研究结果表明: 冻融循环会导致环氧树脂砂浆与混凝土的黏结性能下降, 在25, 50, 75周期后承载力损失分别为38.24%, 42.65%, 52.94%。冻融循环加速黏结材料及围岩的材料性能劣化, 荷载向内部传递加速, 使得GFRP锚杆上各点之间的应力差值逐渐减小, 锚杆应力分布比常温状态下更趋于均匀, 但材料性能的劣化导致局部破坏提前, 锚杆整体承载性能降低。研究结果可以为GFRP锚杆的工程应用提供建议。 相似文献
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已发现的恐龙化石大多数埋藏在不同深度的地层中,不同埋深化石所受风化破坏程度不尽相同。为深入研究恐龙化石的风化机理,探究恐龙化石的保护措施和方法,重点分析埋深产生的侧向压力对恐龙化石强度和破坏特性的影响。通过有限差分软件FLAC3D进行数值模拟,揭示埋深因素对恐龙化石保存的影响程度。试验结果表明:围岩对恐龙化石施加的侧向压力是影响恐龙化石变形和强度特性的一个重要因素。在弹性变形阶段,恐龙化石的初始强度、峰值强度随侧向压力的增大而不断增大。当应力超过了恐龙化石极限强度后进入塑性变形,其初始强度、峰值强度逐渐减小,最终达到残余强度。 相似文献
8.
边坡条分法物理意义是以强度折减表征材料峰值强度的下降程度。以不平衡推力部分强度折减法为例,推广传统假设,应用理想弹塑性模型和全过程剪应力-应变模型,在峰值剪应力和峰值应变相等条件下,模拟边坡的渐进破坏过程;提出了临界状态决定法,随着临界状态逐步移动,边坡不平衡力和驱动力越来越大,抗滑力越来越小,直至整体处于破坏状态。以湖北省恩施州稻池村边坡为例,以3种数值(部分强度折减、理想弹塑性和全过程剪应力-应变本构)模型揭示边坡渐进破坏过程中各参量变化特征。结果表明:3种数值条块法均能描述稻池村边坡渐进破坏过程,基于条分法和理想弹塑性模型部分强度折减系数大于全过程剪应力-应变本构模型稳定系数。 相似文献
9.
高砷高硫银矿有害杂质含量高 ,矿物成份复杂 ,直接氰化浸出率不到 2 0 %,属难选冶银矿。采用固化焙烧—氰化提银工艺 ,银浸出率可达 95 %以上。焙烧产生的As2 O3 、SO2 能以其盐的形式固定于焙砂中 ,不造成环境污染。 相似文献
10.
为了研究软岩地基桥桩的荷载传递性状、破坏机理,并获取在该地质条件下更为可靠的桩基计算参数,对秦巴山区软岩地基3根钻孔灌注试桩进行竖向静载试验.结果表明:秦巴山区软岩地基桥桩试桩荷载沉降曲线呈陡降型,实测竖向极限承载力为20500kN,桩的破坏方式为桩身材料强度破坏;淤泥质亚黏土地层中的碎石起到一定的骨架作用,增强了此地层桩极限侧阻力,发挥极限侧阻力所需的桩土(岩)相对位移为4~8mm;强风化砾岩表现为加工软化型,发挥极限侧阻力所需的桩土(岩)相对位移为3~8mm;中风化砂砾岩表现为明显的加工硬化型,所需的桩岩相对位移大,且桩极限侧阻力的特征点不明显;淤泥质亚黏土地层桩侧阻力占总荷载的60%~70%,随着桩顶荷载的逐步加大,该地层桩侧阻力所占比例不断下降,而嵌岩段桩侧阻力所占比例逐渐上升,达到55%~65%,嵌岩段桩侧阻力沿桩深的分布曲线表现出非线性的特征;试桩为端承摩擦桩,桩端阻力约占桩顶荷载的20%左右,且未充分发挥,在上部结构允许的沉降范围内,适当增加桩端的沉降有利于端阻力的发挥;桩侧阻力先于端阻力发挥,建议单桩承载力设计时分别采用不同的端阻力和侧阻力安全系数. 相似文献
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引碧入连工程，大沙河倒虹吸地质条件复杂，岩性多为淤泥质土和中细砂，前者地基承载力不及８０ｋＰａ，后者有严重的砂土液化问题，为此采用了复合地基处理，提高了地基强度又防止了砂土液化，在施工中应用了静载荷及动力法进行了检测，肯定了复合地基的有效性。 相似文献
12.
SHAN Bo WANG Changming DONG Quanyang TANG Ling ZHANG Guangyi WEI Jiaming 《世界地质(英文版)》2010,13(2):79-84
The collapsibility of loess ground can directly affect stability of subgrade. Therefore, how to adopt practical technical measures to reduce or eliminate its collapse deformation is an important content in foundation design in collapsible loess zone. Selecting collapsible loess from Fuxin-Chaoyang highway in Liaoning, the authors conducted a series of tests for improving loess with cement. The loess in different water content was mixed with the cement in varying proportions, unconfined compression strength for the samples at four different curing periods were tested, and the relationships of improved soil strength among cement mixture ratio and curing periods were analyzed. When the curing periods are certain, the strength of loess increases along with the mixture ratio increases; when the cement mixture ratio is 5%-15%, the scope of increases is quite obvious; when the mixture ratio is greater than 15%, the tendency of intensity increases turns slow. When the mixture ratio for the specimen is certain, the intensity of the test specimen increases along with the curing period increases, the intensity grows obviously in 28 days, and the growth rate is small in 28-90 days, the intensity tends to be steady in the curing period of 90 days. 相似文献
13.
Studying the mechanical properties of the soil-root interface using the pullout test method 总被引：4，自引：0，他引：4
It is important to quantify the effect of the root diameter, the embedment length of the root and load speed on the soil-root interface mechanical properties for studying the root anchorage. The soilroot interface mechanical properties can be obtained through the pullout force and root slippage curve(F-S curve). About 120 Pinus tabulaeformis single roots whose diameters ranged from 1 mm to 10 mm divided into 6 groups based on different root embedment length(50 mm, 100 mm and 150 mm) and different load velocity(10 mm·min~(-1), 50 mm·min~(-1), 100 mm·min~(-1) and 300 mm·min~(-1)) were investigated using the pullout method. This study aims to explore the mechanical properties of the soil-root interface in the real conditions using the pullout test method. The results showed two kinds of pullout test failure modes during the experimental process: breakage failure and pullout failure. The results showed that the roots were easier to be broken when the root diameter was smaller or the loading speed was larger. The relationship between the maximum anchorage force and root diameter was linear and the linearly dependent coefficient(R~2) was larger than 0.85. The anchorage force increased with the root embedment length. An increase of 10%~(-1)5% for the maximumanchorage force was found when load speed increased from 10 to 300 mm.min~(-1). The mean peak slippage of the root was from 13.81 to 35.79 mm when the load velocity varied from 10 to 300 mm.min~(-1). The study will be helpful for the design of slopes reinforced by vegetation and in predicting risk of uprooting of trees, and will have practical benefits for understanding the mechanism of landslide. 相似文献
14.
Grain-size characteristics of sediment in Daniugou peatland in Changbai Mountains,Northeast China: Implications for atmospheric dust deposition 总被引：1，自引：0，他引：1
The grain-size distribution characteristics and grain-size parameters of sediment in two vertical sections of Daniugou peatland
in the Changbai Mountains were systematically investigated. A comparative analysis of the sediment granularity using a discriminative
function with Hongyuan peat, red clay, loess-paleosol, fluvial deposit as well as lacustrine deposit was also conducted. It
turns out that the vertical section of Daniugou peat ash is primarily constituted by clay and silt particles, and the content
of sand is relatively small. Grain-size frequency curves generally show a single-peak modality while a bimodal pattern is
detected in the upper layer. The grain-size component and peak pattern of grain-size frequency curves also illustrate that
peat ash materials were transported to the peatland by long-range aeolian dust during the deposition process, while there
existed short-distance dust influence in peat deposition of the upper layer. Comparisons of grain-size parameters and the
discriminative Y-value of Daniugou peat ash with those of typical aeolian sediments show close similarities, suggesting the
possibility that atmospheric dust transport processes were involved in the accumulation of peat again. Moreover, the variations
of grain-size distribution suggest the local environmental deterioration which is just the driving force of local dust elevation.
Grain-size analysis of peatland sediment is demonstrated to be one effective method to extract information about regional
and global environmental evolution, and more attention should be paid to current local ecological environment and to seeking
a balance between economic development and environmental protection in Northeast China. 相似文献
15.
地基是工程建设的基础,其承载力计算和预测十分关键,决定着建筑工程上部结构的安全性与稳定性。为实现小数据量、短周期、较高精度的地基承载力预测。本研究提出以地基静载试验数据为依据,利用灰色模型进行计算,结合马尔科夫优化,建立灰色马尔科夫预测模型,预测固定荷载作用下的地基沉降,进而明确相应沉降下的基地承载力。同时,将该模型与传统的灰色GM(1, 1)模型、指数曲线拟合模型进行对比,分析3种模型的优劣。结果表明,案例一中,静载试验下的地基承载能力完好,灰色马尔科夫模型、GM(1, 1)模型、指数曲线模型预测值与实测值的平均相对误差依次为1.55%,3.80%,10.22%,灰色马尔科夫模型精度最高,更契合地基静载试验,能准确有效地明确地基承载力;案例二中,地基在静载试验下发生破坏,破坏前灰色马尔科夫模型预测值与实测值的平均相对误差仅为0.5%,预测效果良好。破坏时,地基沉降迅速增加,加载点模型预测值与实测值的相对误差出现异常,骤增至26.29%,以此可判断破坏前一级加载序列荷载为该地基的极限承载力。运用此模型指导地基静载试验,在保障工程施工安全的前提下,相邻试验点可以适当减少静载试验次数,节约工程施工成本,为信息化地基静载试验提供一个新的计算工具。 相似文献
16.
SahelbioclimaticzonecrossNorthAfricabe-tweenl7oNandl3"Nborders,theSaharaDeserttothenorthandtheSudansavannatothesouth,beinganimportantfragileecologicalzoneintheworld.SincethesevereSudano-Saheliandroughtof1968-l973sandydesertificationhasresultedinaverymiserableconse-quencestolocalpeople,asaSahelcountryinwestAhica,theRepublicofMaliisoneofthecountriesmostseverelyaffectedbydroughtanddesertification,AccordingtotheinvestigationsoftheexpertgroupoftheLanzhouInstituteofDesertResearch,theChineseA-… 相似文献
17.
《世界地质(英文版)》2015,(3)
Calcareous sand is a kind of special medium which is composed of calcium carbonate and other difficult soluble carbonate substances. Because of its rich in inner pore space and easy crashed,the mechanical property is very different from conventional quartz sand. Based on the compaction test and direct shear test of calcareous sand,by means of data fitting,the coupling relationship between compaction density and mechanical property under different water contents was obtained; meanwhile,the shear strength expression was built on the basis of the relationship between water content and dry density. 相似文献