共查询到17条相似文献，搜索用时 140 毫秒
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顶管施工对邻近地下管线的影响预测分析 总被引：3，自引：0，他引：3
采用通用Peck公式计算顶管施工引起的地下管线平面处的土体竖向位移。对地下管线的受力模型进行简化,基于Winkler地基模型,得到地下管线由于顶管开挖引起的极限弯矩、理论弯矩以及管线变形的计算方法。通过算例分析,与连续弹性解、Attewell解和王涛解的计算结果进行比较,探讨了土质条件、管线材质、管线埋深、管线管径对地下管线受力的影响。计算结果表明,本方法适用于各种土质,可较好地预估管线所受弯矩,且不会低估管线所受的最大弯矩;在相同条件下,管线埋深越大承受的弯矩也越大,但埋深仅对最大正弯矩和最大负弯矩位置附近处的管线影响较大,对其余部位影响较小;管线抗弯刚度越大,管线承受的极限弯矩和影响范围也越大;管线管径越大,管线承受的弯矩也越大。 相似文献
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隧道开挖引起的地层不均匀沉降造成附近的地埋管线产生额外的变形,甚至破坏。被动管线与土体的相互作用的研究表明,不考虑土体的刚度衰减,较大的土体弹性模量使得管线的最大弯矩计算结果过大,偏于保守,造成不必要的浪费。在被动管线Winkler地基模型分析基础上,引入土体刚度衰减模型考虑土体非线性特性,提出了隧道开挖作用下管线响应的等效线性分析方法。基于自由土体位移场计算管周土体由于隧道开挖引起的附加应变,基于水平受荷桩的环状弹性介质模型考虑由于管土相互作用引起的管周土体应变,从而对被动Winkler地基模型的土体弹性参数进行修正,计算得到管线的最大弯矩。通过与现有的弹性理论方法、离心模型试验结果的对比,验证了针对隧道开挖引起的被动管土相互作用问题,该方法考虑土体非线性特性的合理性。 相似文献
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《岩土力学》2017,(4):1164-1170
隧道开挖和管线置换引起的应力变化将不可避免地导致土体位移,进而对上覆既有管线产生诸多的不利影响。国内外学者对管-土相互作用开展了大量的研究,但用于预估隧道开挖和管线置换引起既有管线弯曲变形的简单并且有效的设计图表尚未提出。采用ABAQUS商业软件,对隧道-土-管线、管线置换-土-管线间的相互作用开展系统的有限元仿真模拟。通过采用管线不同运动方向下的等效管-土相对刚度,提出了隧道开挖和管线置换引起的管线弯曲变形的设计图表,并采用现场实测数据和离心模型试验结果验证此设计图表的合理性。设计图表中的管线最大弯曲曲率与土体最大曲率的比值和管-土相对刚度具有非常好的相关性。工程师一旦得到隧道开挖或管线置换引起的土体位移、管线尺寸、管线参数和土体参数,此设计图表可用来预测隧道开挖或管线置换引起既有管线的最大弯曲曲率。 相似文献
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以上海地铁11号线某区间盾构工程为背景,采用相似物理模型试验研究盾构隧道开挖对上方垂直于隧道轴线的地下管线的影响,并将试验结果与数值解对比。采用量纲分析法推导出文中模型试验的相似准则,并基于该相似准则设计出盾构机和隧道模型,分别通过管线刚度试验和模糊数学综合评判方法选定模型管线和配制相似土材料。研究结果表明,自主开发的半自动盾构掘进装置能较好地模拟盾构的开挖过程,较人工开挖扰动更小;下方盾构隧道开挖使管线产生的竖向变形关于隧道轴线呈对称分布,其形态符合高斯曲线的特征,最大竖向变形位于隧道轴线正上方处,竖向变形反弯点出现在与隧道轴线水平距离约一倍隧道直径的位置处;隧道开挖对管线的影响范围随管隧间距的增加而减小,管线竖向变形曲线的反弯点位置随管隧垂直间距的增大而有所内移;管线刚度对管线竖向变形的影响相对较小。 相似文献
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利用弹性力学的Mindlin解,对孙统立公式进行修正,推导得到双圆盾构正面附加推力和盾壳摩擦力引起的土体附加应力计算公式。假定土体为Winkler模型,采用随机介质理论,推导得到土体损失引起的竖向土体附加应力计算公式。研究了双圆盾构施工在邻近垂直交叉地下管线上引起的附加荷载大小及分布规律。研究结果表明：双圆盾构盾壳摩擦力引起的地下管线附加荷载较大;正面附加推力引起的附加荷载较小,可忽略;竖向附加荷载主要由土体损失引起,最大值一般出现在中轴线上方,当地下管线与盾构之间距离较小时,附加荷载最大值出现在左右单圆圆心附近的位置。 相似文献
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顶管施工对相邻平行地下管线位移影响因素分析 总被引：6，自引：2，他引：4
顶管施工引起的管道周围土体移动会对相邻地下管线造成危害。采用三维有限元方法分析了顶管施工引起的相邻平行地下管线的位移,研究了注浆、纠偏、离顶管距离的远近、地下管线埋深、管线与土体弹性模量比及不同管材对地下管线位移的影响。计算结果表明,注浆与纠偏压力越大,地下管线的位移越大;地下管线距离顶管越远,引起的位移越小;地下管线弹性模量越小,产生的位移越大。 相似文献
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基坑开挖对邻近地下管线影响的变形控制标准 总被引：8，自引：0，他引：8
基坑开挖会引起邻近区域地埋管线的附加受力和变形,甚至会引起管线的开裂破坏。基于位移控制理论,对板式支护体系由于基坑开挖而引起的周边自由土体位移场的分布规律进行了探讨,通过位移控制两阶段简化分析方法与位移控制有限元方法的对比,验证了简化方法的合理性。其次对最近修订的《上海市基坑工程技术规范》的基坑环境保护标准进行了探讨,利用简化方法通过算例计算以分析其仍需改进的方面,在此基础上,基于地下管线的自身承受能力,提出了基坑开挖对管线保护的变形控制标准,给出了为保证管线正常使用,基坑开挖深度与基坑允许侧向变形的关系,从而可以为基坑开挖环境影响评价标准的建设提供相应的理论依据。 相似文献
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邻近开挖对既有软土隧道的影响 总被引：11，自引：1，他引：10
采用两阶段分析方法,提出了邻近开挖对既有软土隧道纵向受力变形影响的简化计算方法。针对软土隧道开挖情况,第1阶段采用Loganathan和Poulos提出的解析解计算开挖引起的土体自由位移场;针对基坑开挖情况,第1阶段根据Mindlin理论解计算邻近荷载作用引起隧道的附加应力;第2阶段基于Winkler地基模型将既有隧道视为弹性地基无限长梁,将土体自由位移或附加应力施加于隧道,并建立求解该问题的纵向变形方程,从而得到隧道纵向位移和内力的计算表达式。结合离心模型试验结果和工程实例进行分析,验证了方法的有效性。研究成果可为合理制定邻近施工对软土隧道的保护措施提供依据。 相似文献
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采用Loganathan公式研究了盾构隧道下穿管道施工引起的地下管道处土体竖向位移,利用考虑土中剪力传递的Pasternak模型模拟管-土相互作用,运用修正Vlasov模型中的迭代流程计算出Pasternak模型的关键参数——弹性系数k与剪切系数gs。将计算结果与已有文献结果及工程监测数据进行对比,深入分析了迭代求解k、gs值的Pasternak模型与传统模型的计算差异,并进一步研究了土中剪力、管道与隧道的夹角、土体弹性模量及隧道半径的变化对管-土相互作用的影响。研究结果表明：迭代求解的k、gs值能提升Pasternak模型的精确度;土中剪力对管道竖向位移计算值的影响可达15.3%;随着管道与隧道夹角的减小,管道的竖向位移增大、弯矩减小;土体弹性模量与隧道半径的增大均会增加管道的竖向位移和弯矩。 相似文献
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Rosendo Danilo C. Albuquerque Paulo J. R. 《Geotechnical and Geological Engineering》2021,39(2):765-782
Piles subjected to lateral loading can create problems in soil-structure interaction. Several differing methods of analysis have been proposed to solve the problem of laterally loaded piles, resulting in the determination of pile bending and the bending moment as a function of depth below soil surface. These piles are widely used to support laterally loaded piles, such as bridge pillars, offshore platforms, communication towers and others. This study presents an analytical solution to Miche’s problem as a continuous function of depth: deflection and moment, as well as a dimensional plots to be used in projects involving piles subjected to laterally loading only including data concerning laterally loading test and pile geometry. A new formula is presented to calculate the pile head displacement as well as an equation to determine maximum moment for a generalized Miche model and further analysis. In addition, this paper proposes an equation for the determination of constant horizontal subgrade reaction \((n_{h})\) based on the CPT in-situ test and the geometric characteristics of the pile. Calibration of the analytical model showed good fit and conservative results regarding inclinometer data from an bored pile and good agreement with the literature results.
相似文献13.
Cross-sectional ovalization of buried steel pipes subjected to bending moment induced by end displacements is discussed. A three dimensional finite element analysis was conducted employing Abaqus/CAE. The pipe was simulated using 3D shell elements while the saturated sand soil medium was simulated by employing discrete nonlinear springs along the pipeline. The effects of normalized burial depth (H/D), diameter to wall thickness ratio (D/t), sand density and level of the internal pressure on the ovalization are investigated, and resulting ovalization distribution with respect to bending moment at critical sections is presented. The results of this study enable simple one dimensional finite element models to consider geometrical cross-sectional nonlinearities in the analysis of buried pipelines. 相似文献
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The response of box culverts to static loads is controlled by soil arching. Soil arching is a result of a complex soil culvert interaction (SCI) due to the relative stiffness between the culvert and the surrounding soil, and is a critical consideration in culvert design. The factors that affect soil arching on box culverts include the soil height above the culvert, the geometrical configuration of the box culvert and the properties of the soil around it. Box culverts are typically designed using formulae that assume simplified behaviors and in some cases rely on considerable empiricism. In the present study, small scale centrifuge physical model tests were conducted to investigate SCI considering the height and density of soil above the culvert and the geometry of the culvert. The results of these centrifuge tests were used to calibrate and verify a numerical model that was used to further investigate the response of box culverts to static loads. The results have been evaluated for bending moment and soil culvert interaction factors. The results demonstrated that the soil culvert interaction factors are not only a function of the height of soil column above the culvert, but also a function of the culvert thickness, soil elastic modulus and Poisson’s ratio. Therefore, the results were used to establish charts and equations that can be employed to assess the design values of the static soil pressure and static bending moment for box culverts. 相似文献
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埋地管道在交通荷载等作用下会发生破坏，对区域内的经济和生活造成较大的影响。近年来废弃橡胶轮胎颗粒与土混合成轻质土逐渐被用于路基填料等领域。设计完成了冲击动载下橡胶?粉土轻质混合土中管道动力响应特性的模型试验，采用等体积置换法在地基土中掺入0%、10%、20%、30%的废轮胎颗粒，通过路基的表层沉降以及埋地管道的变形特性来研究轻质混合土作为路基填料的减振性能。试验结果表明，加入橡胶颗粒能有效减小路基表层沉降，当橡胶含量10%时，路基沉降减小最明显；埋地管道在冲击动载的作用下表现出“压扁”的形态特征，加入橡胶颗粒能明显减小埋地管道的应变及弯矩响应，当橡胶含量为20%和30%时，管道的应变和弯矩减小更为明显。 相似文献
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A new method is developed for analysis of flexible foundations (beams) on spatially random elastic soil. The elastic soil underneath the beams is treated as a continuum, characterized by spatially random Young’s modulus and constant Poisson’s ratio. The randomness of the soil Young’s modulus is modeled using a two-dimensional non-Gaussian, homogeneous random field. The beam geometry and Young’s modulus are assumed to be deterministic. The total potential energy of the beam-soil system is minimized, and the governing differential equations and boundary conditions describing the equilibrium configuration of the system are obtained using the variational principles of mechanics. The differential equations are solved using the finite element and finite difference methods to obtain the beam and soil displacements. Four different beam lengths, representing moderately short, moderately long and long beams are analyzed for beam deflection, differential settlement, bending moment and beam shear force. The statistics of the beam responses are investigated using Monte Carlo simulations for different beam-soil modulus ratios and for different variances and scales of fluctuations of the soil Young’s modulus. Suggestions regarding the use of the analysis in design are made. A novelty in the analysis is that the two-dimensional random heterogeneity of soil is taken into account without the use of traditional two-dimensional numerical methods, which makes the new approach computationally efficient. 相似文献
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This article revisits the influences of axial load on the lateral response of single pile with integral equation method. The problem is formulated by decomposing the pile soil system into an extended elastic soil and a fictitious pile, the former of which is analyzed by making use of the fundamental Mindlin's solution for a concentrated horizontal load whereas the latter is modeled by the conventional beam bending theory. According to the rotation compatibility condition between the fictitious pile and the extended soil, a Fredholm integral equation of the second kind is established with the shear strain and rotation angle of the fictitious pile being the basic unknowns. The bending moment and displacement distribution along the pile are subsequently obtained. Comparison with existing solutions validates the accuracy and applicability of the present formulation. The results of parametric analysis indicate that the influences of axial load on the lateral response of single piles could be significant, and in general, the bending moment and horizontal displacement distributions along the pile increase considerably with the increase of axial load. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献