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1.
数值计算方法在土力学中的应用 总被引：2，自引：0，他引：2
本文是对48篇有关数值方法在土力学方面应用的论文进行综述的报告。近年来,在土力学方面有限元和其它数值方法的耦合有了新的发展,动力分析在非线性应力应变关系、三维问题和有效应力分析中得到了进一步的应用,接触单元或连接单元可用来处理有限元计算时的接触条件。数值方法和概率方法的结合是一个值得重视的发展方向。这些方法可应用于估计固结效应、土坡稳定、土石坝、渗流、变形计算、共同作用、桩和地基性状分析等方面。 相似文献
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门架式双排抗滑桩的弹塑性模型与计算分析 总被引：3，自引：0，他引：3
门架式双排抗滑桩的计算模型大部分将桩排间岩土体视为弹性材料,而岩土体为弹塑性材料,使得抗滑桩内力、位移计算结果与实际情况相差较大。假设桩排间岩土体为弹塑性材料,提出一种弹塑性计算模型,该模型将桩排间岩土体看作线弹性单元和塑性单元的组合,根据结构力学知识、土的本构关系和数值分析方法建立一种计算前后排抗滑桩内力的计算方法。首先,由已知的桩顶位移,并结合结构力学位移法求出桩间土总应力。根据Lade-Duncan模型导出这两个单元的基本参数,然后,结合数值分析方法计算出抗滑桩的内力,最后,结合工程实例,运用ANSYS有限元软件进行计算分析,得出门架式双排抗滑桩的内力图。对比监测数据和弹性模型计算结果表明,弹塑性模型的计算结果比弹性模型更加接近监测值。 相似文献
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水流冲刷对桩基承载性状影响的数值模拟 总被引：2，自引：0，他引：2
利用三维有限元耦合数值模型,对水流冲刷作用下桩基础从低承台向高承台的变化过程中承载性状变化的数值模拟方法进行探讨,得出一种较为理想的模拟方法,对于复合地基中的水流冲刷问题及类似桩-土相互作用中的开挖问题的数值模拟有一定的参考价值。结合工程实例,说明工程计算中简单按高承台计算来考虑水流冲刷作用对桩基承载性状的影响是不准确的。通过调整接触面单元和土体单元刚度,更全面地分析了不同条件下冲刷后桩基承载性状的变化规律,说明冲刷后土体有明显的回弹效应,工程计算中不能简单忽略。 相似文献
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降雨入渗条件下非饱和路堤变形与边坡的稳定数值模拟 总被引：1，自引：0，他引：1
对于常常处于非饱和状态的路堤在降雨入渗条件下变形问题的数值模拟研究,由于涉及到非饱和土力学,一直是个热点和难点。现有的强度折减有限元法一般仅对强度指标进行折减,但折减后得到的路堤变形场与实际变形场存在一定差异。论文分析认为,在降雨入渗影响下非饱和路堤不仅强度参数会降低,而且变形参数也会随着应力水平和强度参数的变化而变化。采用基于变模量的弹塑性强度折减法,对不同降雨入渗深度下路堤的变形规律进行数值模拟,并与室内模型试验结果进行比较;同时采用强度折减法和极限平衡法中的Bishop法,分析了不同降雨入渗深度对非饱和路堤稳定性和滑弧变化特征的影响规律。 相似文献
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Numerical studies of anchored sheet pile wall behavior constructed in cut and fill conditions 总被引：1，自引：0，他引：1
The construction of sheet pile walls may involve either excavation of soils in front or backfilling of soils behind the wall. These construction procedures generate different loading conditions in the soil and therefore different wall behavior should also be expected. The conventional methods, which are based on limit equilibrium approach, commonly used in the design of anchored sheet pile walls do not consider the method of construction. However, continuum mechanics numerical methods, such as finite element method, make it possible to incorporate the construction method during the analyses and design of sheet pile walls. The effect of wall construction type for varying soil conditions and wall heights were investigated using finite element modeling and analysis. The influence of construction method on soil behavior, wall deformations, wall bending moments, and anchor forces were investigated. The study results indicate that walls constructed by backfill method yield significantly higher bending moments and wall deformations. This paper presents the results of the numerical parametric study performed and comparative analyses of the anchored sheet pile walls constructed by different construction methods. 相似文献
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Traditional approaches in contact mechanics demand complicated search algorithms at the interface between the contacting bodies. Recently, a new contact method based on the concept of a third medium has been developed, which overcomes the drawbacks of conventional contact mechanics techniques. This new scheme is based on a space filling mesh, in which the contacting bodies can move and interact. The ability and accuracy of this method in predicting displacements, as well as the contact forces, is validated by solving selected numerical examples. The potential merits of this method for analysing geotechnical problems by the finite element method are addressed. 相似文献
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考虑强度各向异性的边坡稳定有限元分析 总被引：1，自引：0，他引：1
天然沉积的土层总是表现出一定程度的强度各向异性,但现有的边坡稳定有限元分析极少考虑各向异性的影响。对大型有限元软件ABAQUS进行二次开发,使其能够考虑土体黏聚力随大主应力方向的变化,动态更新增量迭代求解过程中边坡不同位置处的抗剪强度,进而提出具备安全系数自动搜索功能的各向异性边坡稳定分析方法。计算结果表明,均匀边坡的有限元解与极限分析上限解相差很小。如果采用土体固结方向的黏聚力并按各向同性评价缓坡的稳定性,可能严重高估安全系数,尤其是在黏聚力较高的情况下。与极限分析不同,建立的强度更新有限元模型能够分析成层边坡的稳定性。 相似文献
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This paper outlines the development as well as implementation of a numerical procedure for coupled finite element analysis of dynamic problems in geomechanics, particularly those involving large deformations and soil-structure interaction. The procedure is based on Biot’s theory for the dynamic behaviour of saturated porous media. The nonlinear behaviour of the solid phase of the soil is represented by either the Mohr Coulomb or Modified Cam Clay material model. The interface between soil and structure is modelled by the so-called node-to-segment contact method. The contact algorithm uses a penalty approach to enforce constraints and to prevent rigid body interpenetration. Moreover, the contact algorithm utilises a smooth discretisation of the contact surfaces to decrease numerical oscillations. An Arbitrary Lagrangian–Eulerian (ALE) scheme preserves the quality and topology of the finite element mesh throughout the numerical simulation. The generalised-α method is used to integrate the governing equations of motion in the time domain. Some aspects of the numerical procedure are validated by solving two benchmark problems. Subsequently, dynamic soil behaviour including the development of excess pore-water pressure due to the fast installation of a single pile and the penetration of a free falling torpedo anchor are studied. The numerical results indicate the robustness and applicability of the proposed method. Typical distributions of the predicted excess pore-water pressures generated due to the dynamic penetration of an object into a saturated soil are presented, revealing higher magnitudes of pore pressure at the face of the penetrometer and lower values along the shaft. A smooth discretisation of the contact interface between soil and structure is found to be a crucial factor to avoid severe oscillations in the predicted dynamic response of the soil. 相似文献
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针对重力式挡土墙墙后分层填土对墙身受力影响的问题,深入研究分析墙背土压力动态变化值及规律性,利用大型通用有限元分析软件ADINA,建立了平面应变单元及墙、土接触单元的有限元计算模型,并且综合考虑墙后回填土Mo-hr-Coulomb材料本构模型,初始地应力场平衡、墙后回填土分层碾压填筑,设置墙、土之间的接触受力进行有限元... 相似文献
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对三维问题的分析是数值流形方法发展的必然,在数值流形方法覆盖位移函数的基础上构造了一种六面体有限覆盖的三维流形单元,推导了相应的应变矩阵、刚度矩阵及平衡方程等表达式。同时,由于目前数值流形方法的模拟分析主要是采用线弹性模型,而对于非线性模型分析研究很少;根据数值流形方法的特点和岩土体的本构模型,给出了适用于数值流形方法进行非线性分析的算法。该方法利用中点增量法进行求解,以改变 模型和 模型中弹性模量的方式来反映非线性,其实质是用分段线性来取代非线性。通过地基沉降计算算例表明,数值流形方法在三维岩土体中进行非线性分析中是有效的。 相似文献
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复合本构有限元法是一种新型的复合地基沉降数值计算方法.采用复合本构有限元和传统三维有限元两种计算模型,通过不同桩土模量比、置换率和桩长条件下复合地基沉降计算结果的比较,对复合本构有限元法的适应性进行了探讨. 相似文献
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Coupling of solid deformation and pore pressure for undrained deformation—a discrete element method approach 
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下载免费PDF全文 This paper presents a numerical scheme for fluid‐particle coupling that uses the discrete element method by taking into consideration solid deformation and pore pressure generation. A new water particle element is introduced to calculate pore water pressure due to porosity changes. The water particle element has the same size and shape as the solid element and experiences the same amount of deformation. On the basis of the effective stress principle at the element contact, the total force is equal to the sum of the force transmitted through the solid element contact and the water particle force due to pore water pressure. Analytical solutions of traditional soil mechanics problems, such as isotropic compression and consolidated triaxial undrained test, are used to quantitatively validate the proposed model. The numerical results show good agreement between the model and the analytical solutions. The model therefore provides an effective method to calculate pore pressure in a porous medium in discrete modeling. 相似文献
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考虑到颗粒形状对粗粒料的力学特性有重大影响,提出了一种新的表征颗粒形状的方法,即在椭圆上随机选取一系列点连接成多边形颗粒,表征狭长扁平的颗粒。新方法较圆上取点的方法能代表更多类型的颗粒形状,适用范围更广。提出了一种新的粗粒料投放算法,即先缩小颗粒,然采用随机算法将缩小的颗粒投放至给定区域,对颗粒划分好网格后,将颗粒放大到原来的大小,然后采用有限元-离散元(FEM/DEM)方法计算稳定后即生成了相应的试样。通过将上述颗粒生成及投放算法与FEM/DEM结合,应用于粗粒料的数值模拟。分析表明,FEM/DEM是研究粗粒料力学性质的较好方法,对复杂的颗粒形状也可简单建模,且因在颗粒内部划分了有限元网格,复杂的接触判断及接触力计算转化为标准统一的三角形和三角形之间的接触判断及接触力计算,所有的计算均可标准化、统一化。同时因为颗粒是可以变形的,依然保留了连续介质力学中应力和应变的概念,无须像PFC那样需通过测量圆来间接表示某点的应力、应变。最后,通过粗粒料的侧限压缩试验的数值模拟,展现了文中提出的一整套解决方案在模拟粗粒料方面的巨大潜力。 相似文献
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为准确评估软土地区基坑施工安全以及对周围环境的影响,开挖过程中的时间和空间影响因素不可忽视。以长江漫滩软土地区某深基坑开挖工程为依托,首先建立考虑顺逆结合施工过程的有限元模型,将地连墙水平位移的计算值与实测值进行对比,验证有限元计算的可靠性;基于理论分析、数值计算和实测数据,采用坑角效应影响系数和等效水平抗力系数来衡量时空效应对支护变形的影响,提出考虑时空效应的地连墙变形计算方法;通过工程实例验证了在软土地区基坑设计计算中考虑时空效应的必要性以及所提计算方法的合理性。该研究成果可为软土地区深基坑变形计算提供有益借鉴。 相似文献
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地基极限承载力分析是土力学研究中的一个经典课题。基于Hellinger-Reissner混合变分原理和有限元方法,将岩土体弹塑性问题构造成基于有限元框架的二阶锥规划（second-order cone programming,SOCP）问题,进而提出一种基于二阶锥规划理论的增量有限元法,即FEM-SOCP法。将岩土体弹塑性问题构造成二阶锥规划的数学优化问题,可以避免采用传统弹塑性计算中复杂的应力点积分等算法和屈服面棱角的平滑处理。此外,对于二阶锥规划问题,可以采用具有原始?对偶内点求解法的标准数学规划求解器MOSEK进行求解。将增量加载FEM-SOCP法应用于经典的基底粗糙的条形浅基础地基极限承载力分析中,分别考虑了关联和非关联塑性条件下的Mohr-Coulomb屈服准则。数值结果表明：所提出的增量加载FEM-SOCP法获得的地基承载力系数及地基承载力与传统FEM计算结果基本一致,而与常规有限元计算结果相比,基于增量加载的FEM-SOCP法所获得的屈服区更加平滑。 相似文献
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为了克服现有数值计算方法在计算复杂断裂面接触滑移过程中效率低的问题，通过吸收边界元的建模思想，提出了新的数值计算方法。在该算法中，所有网格均位于岩块的边界，利用显示差分方法计算得到岩块之间的相互作用力以及岩块的位移量。利用“小球在抛物面上滑移”、“哑铃在不同倾角的斜面上”两个模拟试验对文中的算法进行验证，同时利用文中算法与有限元算法对直剪试验进行模拟。结果表明：算法能够准确描述物体之间的相互接触，准确计算得到接触块体之间的法向位移。算法能够准确判断出接触物体的“滑移状态”和“稳定状态”，摩擦力的数值计算结果与解析解的误差小于10?10。在计算断裂面接触和剪应力变化规律时，算法与有限元算法的计算结果一致，但文中计算方法的效率显著提高。 相似文献
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A numerical method is developed in this paper for the analysis of the behaviour of a raft resting on a consolidating soil. The response of the raft under an applied loading is determined using the finite layer method for the soil and the finite element method for the raft. By considering deflection compatibility on the contact surface, the distribution of contact pressure is computed at various time steps. The settlement and bending moment in the raft is then evaluated by applying the calculated contact pressure back to the raft. It is shown that, in some cases, the maximum moment in the raft occurs during consolidation and that checking the final moment in the raft by use of elastic theory may not be sufficient. 相似文献
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D. V. Griffiths 《国际地质力学数值与分析法杂志》1985,9(3):253-259
The influence of pore-fluid compressibility on failure loads in certain soil mechanics problems is investigated. The results are tested using a finite element approach treating the soil as an elasto-plastic material. A limiting value for the pore-fluid compressibility to give satisfactory solutions and numerical stability is suggested. 相似文献