共查询到19条相似文献，搜索用时 203 毫秒
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有纺土工织物加固软土地基可靠性分析 总被引：2，自引：1，他引：2
通过室内模型试验，研究了有纺土工织物加筋地基土的横向位移随深度的变化规律、加筋砂垫层的剪应力分布、加筋对地基承载力的影响，以及土工织物预应力处理后对控制地基土早期变形的作用等，还讨论了施工加质量对加固效果的影响，应用实例的成功表明，按研究成果要求实施工程处理是可行的。 相似文献
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传统锚索形变量有限,在边坡大变形加固中容易出现超限破坏,而高强大变形屈服锚索兼顾高吨位、大变形的要求,能适应地质条件复杂多变的边坡加固。首先基于单根屈服套室内试验,获得3种可稳定输出恒阻的屈服套,其起始屈服力分别为120,135,145 kN,屈服行程大于200 mm。试验表明,单根屈服套起始屈服力总是大于直线平稳段恒力;输出恒力与屈服界面长度呈线性关系。高强大变形锚索的屈服装置由数个挤压摩擦型屈服套组成,其起始屈服力及行程可依据设计调节。目前已自主研发了 400,500,1 000,1 500 kN级系列屈服锚索,室内张拉试验结果表明,锚索屈服行程可达200 mm,各屈服套受力均匀、位移同步。屈服锚索采用P锚作为限位装置以充分发挥钢绞线的抗拉能力。室内极限承载力试验结果表明,400,500 kN级屈服锚索极限承载力可达1 050 kN。高强大变形屈服锚索的吨位及行程具有较好的拓展性,性能优于已有屈服锚杆,可为边坡大变形加固提供一种新的解决方案。 相似文献
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岩体的变形模量是表征岩体抗变形能力的一个重要参数。对于深部破碎岩体的变形模量,采用传统的现场试验法或钻孔弹模法获得其变形参数有一定的局限性。因此,采用一种新开发的试验手段：将现场钻孔中取得的深部破碎岩体试样带回室内,放入MTS中进行三轴试验,记录相应的位移和应力;同时推导了一套配套的理论计算公式,利用室内试验的方法获得了从钻孔中取得的深部破碎岩体的变形模量。采用上述方法对实际水电工程坝基深部破碎带岩体的变形模量进行试验计算,并对试验得到的变形模量结果进行检验分析。其结果表明：采用两种方法获得的深部破碎岩体变形模量值差别一般在10％以内。 相似文献
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坝基软弱破碎地质体是影响大坝安全的关键因素之一,其岩体力学参数的合理确定是大坝工程稳定分析与安全评价的基础。为合理确定向家坝水电工程左岸坝基挤压破碎带的变形模量,进行了室内MTS变形模量试验、现场小型承压板和大型承压板试验研究。3种试验方法得到的破碎带岩体变形模量基本都小于1.0 GPa,有盖层承压板试验条件下的破碎岩体变形模量测试值远大于无盖层岩体影响情况下的试验成果。研究成果表明,不同试验方法反映了左岸坝基破碎带岩体的不同受力状态,其变形模量也呈现一定差异性。在分析挤压破碎带变形模量试验值差异性的原因基础上,提出了左岸坝基破碎带岩体变形模量的建议值。 相似文献
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防波堤土工织物加筋地基离心模型试验及数值模拟 总被引：7，自引：2，他引：5
以黄骅港北防波堤工程为依托,对土工织物加筋软粘土地基及斜坡式防波堤体系的固结过程进行了离心模型试验和有限元数值模拟,通过分析地基土体固结过程中防波堤-加筋垫层-基体系的位移场和应力场的发展及织物拉应力分布和发展,验证离心试验及数值模拟方法的合理性,并得出以下几点主要结论:(1)土工织物加筋垫层的作用机理为其抗拉性限制自身横向变形,通过与附近土体的摩擦作用限制其侧向变形;(2)加筋减小防波堤-垫层-地基体系的高应力水平区,避免堤身与地基高应力水平区域的连通,增强系统稳定性;(3)在离心试验采用的分层地基的条件下,加筋减小了浅层软基和堤身的侧向位移量,对系统总位移有抑制作用;(4)试验中织物替代材料的极限拉伸强度发挥程度较低,其与砂垫层间摩擦强度的发挥水平约为23.8％。 相似文献
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加筋膨胀土不同布筋型式三轴试验研究 总被引：1，自引：0，他引：1
基于三轴试验方法,对不同布筋方式的加筋膨胀土试样的强度特性和变形过程进行研究。室内三轴试验表明,非均匀加筋型式较适合低围压、变形小的加筋土体工程;高围压、大变形的加筋土体工程采用均匀布筋型式将会取得较好的效果。试样变形过程表明,加筋试样随着轴压的增加,将会形成多鼓状变形,并且中间土体最终变形将超过端部土体变形;该变形过程可较好地解释加筋挡土墙随着时间和外部荷载的作用出现中间部分突出的现象。试验结果对加筋土体施工将会起到一定的指导意义。 相似文献
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岩体变形模量是岩体工程设计最重要的参数之一.由于受到资金、时间、尺寸效应等限制, 在工程勘察设计阶段往往不可能大量开展岩体现场和室内变形模量试验, 试验结果也不具有普遍代表性.因此, 水电工程常常采用岩体纵波波速与变形模量之间的相关关系来估算大范围及深部岩体变形模量.根据波动微分方程从理论上解释了岩体纵波波速与变形模量之间内在的联系.以我国西南金沙江干流上坝基主要为玄武岩体的4个大型水电工程为例, 根据132组现场变形模量试验结果与同向波速测试结果建立玄武岩体波速与变形模量相关方程, 并与也有的研究成果对比分析.研究成果表明, 玄武岩体波速与变形模量具有较好的相关性.当波速小于4 500 m/s时, 不同类型玄武岩根据波速计算变形模量差别较小; 当波速大于4 500 m/s时, 差别逐渐增加.选取最优的相关方程用于估算坝基玄武岩体变形模量, 为水电工程坝基玄武岩体变形模量的快捷评价提供科学依据. 相似文献
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在滨海区海相沉积土地基的压缩性评价和计算中,压缩模量是一个重要的土性指标,尤其是在变形要求严格的工程中,对于压缩模量取值的研究具有重要意义。以我国北方某填海造地机场工程场区地基土为研究对象,进行原位测试和变形专项研究。在现场采用固定平台取土和测试,通过室内试验获取了各层土的室内试验压缩模量,通过旁压试验、静力触探试验等原位测试方法得到了各层土的相应的压缩模量。通过分析发现,两种原位测试方法得到的压缩模量,与室内试验自重应力下的压缩模量吻合度较好,说明采用固定平台进行测试,成果合理可靠。在具体的计算取值时,如原位测试数据样本充足,推荐以原位测试成果为主,再考虑室内试验自重应力下的压缩模量。 相似文献
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Yang Jun* Li Li Fan Aiwu School of Civil Engineering Mechanics Huazhong University of Science Technology Wuhan China 《中国地质大学学报(英文版)》2005,16(4):349-353
Theapplicationofreinforcedconcrete(RC)shear wallbuildingsisquitecommoninseismicare as.Shearwalls,withlargerigidityandhigh strength,aretheprimarymembersforresistinghori zontalloadsinbuildingstructures.Butunderthe forceofasevereearthquake,shearwallsareprone… 相似文献
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桥梁桩基主动托换中顶升荷载的简化计算 总被引：1，自引：0，他引：1
以福州地铁1号线盾构隧道下穿洗马桥的桩基主动托换工程为依托,针对桥梁上部结构-桩身-土体三者共同组成的复杂超静定结构,运用数值模拟方法和现场实测数据,分析了在不同顶升荷载作用下复杂超静定结构的内力与位移响应,重点讨论了托换过程中上、下部结构的相对刚度及其对顶升荷载的影响;根据顶升荷载作用点以下桩身轴力接近0的条件,确定了桥墩盖梁与薄壁桥台梁两种典型工况下的桩基顶升荷载分别为1 800 kN和2 600 kN。现场监测结果表明,顶升过程中上部结构的位移值和桩身轴力变化值,均与计算结果吻合较好。在此基础上,提出基于上、下部结构刚度比的顶升荷载简化计算方法,研究结果可为类似复杂超静定结构的桩基主动托换工程提供参考和借鉴。 相似文献
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A parametric study of stability of geotextile-reinforced soil above an underground cavity 总被引：1，自引：1，他引：0
Abbas Tahmasebipoor R. Noorzad E. Shooshpasha A. Barari 《Arabian Journal of Geosciences》2012,5(3):449-456
A study based on two-dimensional finite element analyses under plane strain condition was performed by PLAXIS code to investigate the behavior of geotextile-reinforced soil above an underground cavity. The effects of depth of single layer, tensile stiffness, number and length of reinforcement layers, and size of cavity on settlement of ground surface and head of cavity have been investigated. Results indicated that when a single layer of reinforcement is used, there is a critical depth at which settlements are maximum. Maximum settlements reduce with increase in stiffness of reinforcement. Also settlements reduce with increase in number and length of reinforcement but there is a critical value for number and length of geotextile which increase more than this certain value has not significant effect on reduction of settlements. Also for a given load and tensile stiffness, increase in length of reinforcement has more effect for higher diameter of cavity. 相似文献
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双排桩支护组合体系作为一种新型悬臂类支护结构,其整体刚度的提升有利于保持基坑边侧的安全稳定。本文依托于张家口万全区某双排桩基坑支护工程案例,以现有双排桩冠梁刚度系数计算方法为基础,引入冠梁与连梁作用效应系数优化改进考虑连梁和冠梁作用的基坑矩形双排桩支护结构横向支撑刚度的计算方法,并对双梁组合支护体系下不同土性对双排桩前后排桩桩身最大横向位移的影响进行探讨。结果显示:（1）在双排桩结构计算中需考虑冠梁与连梁对双排支护桩的共同横向约束作用,并将冠梁与连梁的刚性连接作为一个整体以提高矩形双排桩双梁横向支撑刚度系数。（2）双梁组合支护体系组合刚度对桩顶位移有较大影响,组合刚度为40～50 MN/m下的位移与观测值较为贴近;冠梁计算长度与引入的冠梁与连梁作用效应系数对双梁组合支护体系组合刚度影响较大,计算长度对组合刚度呈负相关,效应系数对组合刚度呈正相关。（3）双梁组合支护体系下双排桩横向支撑刚度受前后排桩竖向与横向位移差影响,前后排桩桩身最大横向位移受土层内摩擦角、黏聚力和土体水平抗力比例系数影响;改变抗拉强度不会影响双排桩桩体位移。在基坑埋深以下及桩底范围内桩身存在位移拐点,拐点处各不同内摩擦角、不同黏聚力条件下位移相等。 相似文献
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等厚度水泥土搅拌墙技术即TRD工法,近年来在深基坑工程中得到了广泛应用。以上海国际金融中心基坑工程开展的0.7 m厚、8 m宽、56.7 m深TRD成墙试验为背景,采用有限元方法,并基于土体小应变本构模型对其成墙过程进行了模拟,得到了土体侧向位移和地表沉降曲线,并与实测数据进行了对比。结果表明,距离墙体5 m处两者的土体侧向位移曲线基本一致,而距离墙体1.4 m处的土体侧向位移在深度大于20 m后的计算结果较实测值偏小;地表沉降在靠近墙体处最大,随着距墙体的距离增大而逐渐减小。最后分析了成墙深度对地表沉降和土体侧向变形的影响,结果表明,深度越深,引起的土体侧向变形和地表沉降也越大。通过不同成墙深度引起的地表沉降归一化曲线可看出,TRD成墙引起的最大地表沉降约为0.05%H（H为成墙深度）,沉降影响区域约为1.8H。 相似文献
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Bearing capacity of two close strip footings on soft clay reinforced with geotextile 总被引：1，自引：1，他引：0
For many years ago, the beneficial effects of using reinforcement to improve the property of soil have been demonstrated. Over the last three decades, the use of polymeric reinforcement such as geotextile has increased in geotechnical engineering. Among the possible applications, earth reinforcement techniques have become useful and economical techniques to solve many problems in geotechnical engineering practice, such as improve the bearing capacity and settlement characteristics of the footing. This research presents the effect of geotextile inclusion on the bearing capacity of two close strip footings located at the surface of soft clay. A broad series of finite element analysis were performed on two footings with width of 1 and 2 m using two-dimensional plane strain model using the computer code Plaxis (ver 8). Only one type of soft clay was used for the analysis, and the soil was represented by two yielding criteria including hardening soil model and Mohr–Coulomb model, while reinforcement was represented by elastic element, and at the interface between the reinforcements and soft clay, interface elements have been used. A wide range of boundary conditions, including unreinforced and reinforced cases, was analyzed by varying parameters such as number of geotextile layers, vertical spacing of layers, depth to topmost layer of geotextile, tensile stiffness of geotextile layers, and distance of between two footings. From numerical results, the bearing capacity ratio and the interference factor of the foundations have been estimated. On the basis of the analysis performed in this research, it can be concluded that there is a best distance between footings and optimum depth for topmost layer to achieve maximum bearing capacity for closely spaced strip footings. The bearing capacity was also found to increase with increasing number of reinforcement layers if the reinforcements were placed within a range of effective depths. In addition, the analysis indicated that increasing reinforcement stiffness beyond a threshold value does not result in a further increase in the bearing capacity. 相似文献
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Kousik Deb N. Sivakugan Sarvesh Chandra P. K. Basudhar 《Geotechnical and Geological Engineering》2007,25(6):639-646
In this paper, considering the plain strain conditions, a numerical study has been conducted to investigate the behavior of
multi layer geosynthetic-reinforced granular bed overlying a soft soil using the Fast Lagrangian Analysis of Continua (FLAC)
program. The granular fill, soft soil, and geosynthetic reinforcements are considered as linear elastic materials. The geosynthetic
reinforcements are modeled as cable elements fully bonded with the surrounding soil, thus neglecting any slip. The results
obtained from the present investigation showed very close agreement when compared with the results of finite element analysis
and lumped parameter modeling. The distribution of vertical, lateral and shear stresses in the soil are greatly affected as
the number of reinforcement layers is increased. If the tensile stiffness of geosynthetic layers increases and its value is
no more than 4,000–5,000 kN/m, the settlement of the reinforced foundation decreases significantly. The reduction in settlement
is insignificant when the tensile strength of the geosynthetics exceed the above value. 相似文献
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Slope instability arisen along with dam construction is a common problem of great concern in reservoir areas. Thus, displacement monitoring of active slopes is of great importance for the safety of dam operation. The unstable Guobu slope is located only about 1.5 km away from Laxiwa hydropower station in upstream Yellow River. In this study, Synthetic Aperture Radar (SAR) datasets acquired by C-band Environmental Satellite (ENVISAT) Advanced Synthetic Aperture Radar (ASAR), L-band Advanced Land Observing Satellite 2 (ALOS-2) Phased Array type L-band Synthetic Aperture Radar 2 (PALSAR-2), and X-band TerraSAR-X covering different evolution stages of Guobu slope were collected to investigate the displacement history so as to facilitate understanding of its deformation and failure mechanisms. The displacements occurred during the past decade were quantitatively identified for the first time by SAR pixel offset tracking analyses. The results show that before the reservoir impoundment, the maximum accumulative displacements on the slope were more than 7 m from 2003 to 2008, while the post-impoundment displacements also exceeded 7 m in just 1 year from September 2009 to September 2010. Furthermore, this slope is still in active deformation up to now. Nevertheless, the displacement rates seem decreased recently according to the interferometric results of TerraSAR-X data pairs from September 2015 to March 2016. 相似文献