共查询到20条相似文献，搜索用时 31 毫秒
1.
自加筋土出现以来,由面板、筋材、填土组成的加筋土挡墙被广泛研究并应于道路、铁路等土建工程中。填土的压实对加筋土挡墙的变形、土压力及筋材拉力等影响显著。为研究填土相对密实度对加筋土挡墙的影响,进行了3组不同相对密实度的离心模型试验,通过试验数据分析得到以下结论：相对密实度越大,墙体变形越小,特别是加载期变形量;压实可增大面板附近土体约束,使水平土压力大于设计值;试验挡墙设计较保守,筋材填土界面摩擦系数小于设计值;筋材面板之间连接拉力分析表明,连接拉力实测值小于测试土压力。 相似文献
2.
One of the most important factors in optimized design of non-yielding retaining walls like basement walls and bridge abutments is to determine the exact variation of earth pressure acting on such walls. In this paper, the distribution of at rest earth pressure behind a laboratory model of a fixed and rigid retaining wall with a cohesionless dry backfill is measured under the effect of static and repeated loads. The same conditions of the experimental model are then simulated numerically with a two-dimensional finite-difference analysis computer code. For the purpose of model verification, the results of numerical model are compared to the results of the experimental model, which is similar in geometrical and geomechanical properties. Cyclic surcharges with different amplitudes and frequencies are applied in different distances from the wall, and the earth pressure distribution, the resultant force, and its point of application are investigated. The effect of soil and loading parameters on the at rest earth pressure is also evaluated, and a parametric study has been carried out. The results of model show a significant increase in the earth pressure due to cyclic loading compared to static loading, especially in the initial cycles of loading. It indicates that the effect of cycling nature of loading should be essentially taken into account in the design of retaining walls. 相似文献
3.
加筋土挡墙因其特有的景观性能、协调变形性能而日益受到设计者青睐。面板作为加筋土挡墙的组成部分,对墙体的承载能力影响显著。针对现有设计规范无法考虑面板形式对结构自身力学变形特性的影响,设计并开展了整体式与分块式面板的离心模型试验。数据测试分析显示：整体式面板加载期的位移小于分块式面板位移;由于分块式面板位移较大,所以其水平土压力小于整体式面板土压力;加筋土挡墙面板底部存在应力集中现象;分块式面板筋-土界面的摩擦系数发挥值大于整体式面板数值,但两者均小于设计规范建议值;由于模型筋材长度较长并且连接件的存在,导致原型设计较为保守。 相似文献
4.
为研究加筋土桥台结构在顶部条基动载作用下的动力响应问题,通过MTS伺服加载系统施加循环动载,开展室内加筋桥台挡墙动载破坏试验,对比分析3种格栅长度和3类格栅型式的加筋土挡墙沉降及面板水平位移、土压力、筋材应变等参数的分布规律,揭示加筋桥台挡墙的动力承载性能。试验结果表明：在循环动载下不同格栅长度及型式的加筋桥台挡墙破坏模式存在差异,M、A、B型格栅加筋长度 1.0H（H为挡墙高）的挡墙破坏模式均为冲切剪切破坏,A、B型格栅 0.7H和 0.4H的挡墙破坏模式为局部剪切破坏。加筋桥台挡墙面板侧移随筋材长度增加依次减小,A型格栅加筋土挡墙侧移系数总体上相比B型小。桥台挡墙因加筋格栅长度及型式不同导致动土压力衰减规律差异明显,当 1.0H时M型及A型筋材竖向动土压力衰减系数沿墙高呈抛物线函数模型,当 0.7H时,A型和B型筋材竖向动土压力衰减系数沿墙高皆呈指数函数模型。 相似文献
6.
Analysis and Design of Retaining Wall having Reinforced Cohesive Frictional Backfill 总被引：1，自引：0，他引：1
The case of a rigid wall with inclined back face retaining reinforced cohesive-frictional backfill subjected to uniformly
distributed surcharge load has been analyzed using limit equilibrium approach. The analysis considers the stability of an
element of the failure wedge, which is assumed to develop in the reinforced earth mass adjoining the back face of wall. The
non-dimensional charts have been developed for computing the lateral earth pressure on wall and the height of its point of
application above the base of wall. The theoretical findings have been verified by model tests on a rigid wall retaining a
dry cohesive-frictional soil reinforced by geogrid strips. Experimental results are in good agreement with the theoretical
predictions. A design example has been included to illustrate the design procedure. 相似文献
7.
Lazhar Belabed Hacene Benyaghla Jarir Yahiaoui 《Geotechnical and Geological Engineering》2011,29(4):443-452
The stabilization of slopes by the technique of reinforced earth (Terre Armée) is a very economical and reliable technique.
We propose in this paper to check the overall internal stability of the reinforced earth retaining walls by three mechanical
models, using the analytical method of the limit equilibrium (failure). The main objective of this paper is to compare these
failure mechanical models with the failure models obtained by numerical analysis (code FLAC 2D), in order to validate the
most realistic and more unfavourable failure models. Parametric and comparative studies carried out have allowed us to bring
a very useful knowledge concerning the study of the internal stability of the reinforced earth retaining walls. It also proposed
a theoretical mechanical model of calculation proved by numerical simulation. 相似文献
8.
Huiming Tang Wenping Gong Liangqing Wang C. Hsein Juang James R. Martin Changdong Li 《国际地质力学数值与分析法杂志》2019,43(7):1516-1536
Though the technology of using stabilizing piles to prevent landsliding is not new, the design of such piles with a meaningful optimization framework has been rarely reported. In this paper, a multiobjective optimization-based framework for design of stabilizing piles is presented, in which both reinforcement effectiveness and cost efficiency could be explicitly considered. The design parameters considered in the proposed design framework are the pile parameters, including pile diameter, spacing, length, and position, and the design objectives considered are the reinforcement effectiveness and cost efficiency. The design of stabilizing piles is then implemented as a multiobjective optimization problem. In that the desire to maximize the reinforcement effectiveness and that to maximize the cost efficiency are two conflicting objectives, the output of this multiobjective optimization will be a Pareto front that depicts a trade-off between these two design objectives. With the obtained Pareto front, an informed decision regarding the design of stabilizing piles is reached. The effectiveness and significance of the proposed multiobjective optimization-based design framework for stabilizing piles are demonstrated through two illustrative examples: one is the design of stabilizing piles in a one-layer earth slope and the other the design of stabilizing piles in a two-layer earth slope. Further, parametric analyses are conducted to investigate the influences of the pile design parameters on the stability of reinforced slopes. 相似文献
9.
为研究加筋土挡墙在墙顶荷载作用下土体受力和变形形态,通过改变筋材层数、筋材长度和替换加筋材料等方式对加筋土挡墙进行了4种工况的模型试验。对4种工况下的加筋土墙体内竖向土压力、墙面水平位移、墙顶竖向位移和筋材应变等进行对比研究。研究表明,挡墙上部竖向土压力增长较快且各层竖向土压力最大值由加载点下部向墙面处移动;墙顶荷载超过130 kPa时,由于不均匀沉降,第5层筋材对应墙面处有向内收缩趋势,墙面水平位移最大值大约在上三分点位置;整个加载阶段,筋材总体应变值增幅不大且远小于筋材设计应变峰值;增加挡墙内筋材层数和增加筋材长度均可提升挡墙各方面性能,但增加筋材层数提高效果要优于增加筋材长度;使用废旧轮胎代替单向格栅进行加筋可有效提高挡墙整体性能,分散超载引起的附加应力,有效减小墙面水平位移和墙顶竖向位移。 相似文献
10.
The present study pertains to the finding of the lower bound solution, formulating it as a non-linear programming problem using the generalized method developed by Lysmer with certain variations to incorporate the non-linear no-yield condition constraints directly in the analysis. The method considers the family of plane stress fields having the property that all stresses vary linearly within each triangular element of some mesh which covers the soil mass under study. For this type of stress field it is possible to express all equilibrium conditions as a set of linear constraints and the no-yield as a set of non-linear constraints. The boundary condition constraints may be of linear equality or inequality type. By expressing some of the design variables in terms of the remaining variables the linear equality constraints are implicity satisfied. Such a technique minimizes the complexity of the problem by eliminating the equality constraints and reduces the dimensionality of the problem, saving much, computational effort. The optimal lower bound is isolated by formulating it as a non-linear programming (NLP) problem subjected to both linear and non-linear inequality constraints. The sequential unconstrained minimization technique using the extended penalty function method as suggested by Kavlie has been used to isolate the optimal lower bound. The method has successfully been applied to the passive earth pressure and bearing capacity problem. Numerical results are obtained and compared with Lysmer's solution to show the effectiveness of the present approach. 相似文献
11.
12.
The stability analysis of curved earth retaining walls, stabilized by reinforcing membranes, is investigated by means of a multiphase model developed in the framework of the yield design approach. This model is an extension of that previously developed for soils reinforced by linear inclusions. It combines the advantage of a homogenization approach in terms of improved computational efficiency, with its capability to account for a specific soil–reinforcement failure condition, in a rational and systematic way. Application of this model is performed on the illustrative example of a cylindrical‐reinforced retaining wall by means of the kinematic approach of yield design, which provides upper bound estimates for the retaining wall stability factor. Nondimensional charts are finally presented assessing the influence of relevant parameters such as the curvature of the wall, the length of the reinforcing membranes or the reinforcement pull‐out resistance. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
13.
A simple model for the corrosion‐induced loss of stiffness and strength of the steel strips of earth‐reinforced walls was introduced in a finite element simulation of the long‐term behavior of the wall, in which the backfill‐strips interactions are taken into account by means of a generalized homogenization procedure (called a multiphase model). The results show an initial phase of slow displacements induced by the loss of stiffness, followed after a few decades by a steep acceleration of the displacements, leading to wall failure. The influences of the parameter controlling corrosion, the backfill cohesion and the heterogeneity of the corrosion process are discussed. Results are used to discuss a strategy for reinforced earth wall surveillance. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
14.
阻滑桩加固土坡稳定性分析的上限解法 总被引：1，自引：0，他引：1
从极限分析机动学方法出发,利用土的抗剪强度折减系数概念,建立了土坡的极限平衡状态方程,由此确定土坡的临界稳定安全系数及其相应的潜在破坏模式.对于典型问题,通过与现有极限平衡解和有限元数值解的对比分析,验证了这种上限解法的合理性.进而对于在给定的荷载条件下不能满足抗滑稳定性要求的土坡,考虑采用阻滑桩加固方式,根据桩侧有效土压力的合理分布模式确定桩体与滑动面相交的截面上等效抗滑力和抗滑力矩,利用极限分析上限定理建立了阻滑桩加固土坡的极限平衡状态方程,将桩侧土压力作为目标函数,运用数学规划方法确定了极限平衡状态时的临界桩侧土压力,以此为土坡加固中阻滑桩设计提供依据.通过数值计算与分析探讨了阻滑桩加固位置的优化布置等问题. 相似文献
15.
Debabrata Giri 《Geomechanics and Geoengineering》2014,9(1):72-78
The designing of retaining walls requires the complete knowledge of earth pressure distribution. Under earthquake conditions the design needs special attention to reduce the devastating effect, but under seismic conditions, the available literature mostly uses the pseudo-static analytical solution as an approximate to the real dynamic nature of the complex problem. This paper shows a detailed study on the seismic passive earth thrust behind a cantilever retaining wall with inclined backfill surface by pseudo-dynamic analysis. A planar failure surface has been considered. The effect of variation of parameters such as soil friction angle, wall friction angle and back fill inclination have been explored. A complete analysis shows that the time dependent non-linear behaviour of the pressure distribution obtained in the present method results in more realistic design values of earth pressures under earthquake conditions. Results are provided in tabular and graphical non-dimensional form and compared thoroughly with the existing values in the literature. 相似文献
16.
Mansoureh Jesmani Mathias C. Bellout Remus Hanea Bjarne Foss 《Computational Geosciences》2016,20(6):1185-1209
This work considers the well placement problem in reservoir management and field development optimization. In particular, it emphasizes embedding realistic and practical constraints into a mathematical optimization formulation. Such constraints are a prerequisite for the wider use of mathematical optimization techniques in well placement problems, since constraints are a way to incorporate reservoir engineering knowledge into the problem formulation. There are important design limitations that are used by the field development team when treating the well placement problem, and these limitations need to be articulated and eventually formalized within the problem before conducting the search for optimal well placements. In addition, these design limitations may be explicit or implicit. In this work, various design limitations pertaining to well locations have been developed in close collaboration with a field operator on the Norwegian Continental Shelf. Moreover, this work focuses on developing constraint-handling capability to enforce these various considerations during optimization. In particular, the Particle Swarm Optimization (PSO) algorithm is applied to optimize for the well locations, and various practical well placement constraints are incorporated into the PSO algorithm using two different constraint-handling techniques: a decoder procedure and the penalty method. The decoder procedure maps the feasible search space onto a cube and has the advantage of not requiring parameter tuning. The penalty method converts the constrained optimization problem into an unconstrained one by introducing an additional term, which is called a penalty function, to the objective function. In contrast to the penalty method, only feasible solutions are evaluated in the decoder method. Through numerical simulations, a comparison between the penalty method and the decoder technique is performed for two cases. We show that the decoder technique can easily be implemented for the well placement problem, and furthermore, that it performs better than the penalty method in most of the cases. 相似文献
17.
Reinforced soil walls commonly include facing elements which affect the mechanical behavior of the system. However, the design procedures involved in the existing codes and manuals (e.g. FHWA, BS8006, AASHTO, etc.) do not consider the structural contribution of the facing to the wall stability. Recently, a new computer based method for the analysis of reinforced soil walls which takes into account the interaction between the facing and the soil reinforcement layers was presented [Klar A and Sas T. Rational approach for the analysis of segmental reinforced soil walls based on kinematic constraints. Geotextiles and Geomembranes 2009;27:332-340]. This method demands full compatibility between the reinforcement layers and the deforming wall, and is solved as an optimization problem on this constraint. This kinematic compatibility (KC) method entails several assumptions regarding the interaction between the three components of the system (soil, wall, and reinforcement). This paper compares the KC method to a more rigorous continuum analysis. Results show that the KC method is capable of replicating the behavior of the more rigorous system, with a good agreement on both the value of maximum tensile forces in the reinforcement and shear and bending moment distributions along the wall. The KC method has a certain advantage over continuum methods, such as finite element or finite difference, since it requires limited input data that can easily be obtained from field tests. 相似文献
18.
挡土墙库仑土压力的遗传算法求解分析 总被引：6，自引：1，他引：5
在对破裂面上滑动土体静力极限平衡分析的基础上,建立了基于优化方法求解无黏性土、黏性土库仑土压力的自变量取值区间和目标函数模型,并采用遗传进化方法进行了实例求解分析。研究结果表明,遗传算法在计算挡土墙库仑主动土压力的过程中,收敛速度快、用时短,并具有较高的计算精度。算例1中5组无黏性土挡土墙的主动土压力的计算结果与经典库仑解析解非常接近,平均误差为1.748 %,平均进化代数为15代。算例2中8组黏性土挡土墙的主动土压力计算结果与文献的解答非常吻合,平均误差仅为0.017 %,平均进化代数为17.125代。遗传算法具有良好的适应性和强大的搜索性能,非常适合求解岩土工程优化问题。 相似文献
19.
基于极限分析上限定理与土的抗剪强度折减系数概念,考虑土的强度分布的非均质性与各向异性, 建立了土坡的极限平衡状态方程,由此确定土坡的稳定安全系数及其相应的潜在破坏模式。对于在给定的荷载条件下不能满足抗滑稳定性要求的土坡,考虑采用阻滑桩加固方式,根据桩侧有效土压力的合理分布模式确定桩体与滑动面相交的截面上等效抗滑力和抗滑力矩,考虑土的强度非均质性与各向异性的条件,利用极限分析上限定理建立阻滑桩加固土坡的极限平衡状态方程,将桩侧土压力作为目标函数,运用数学规划方法确定极限平衡状态时的临界桩侧有效土压力。通过大量的变动参数对比计算,探讨了土的强度的非均质性与各向异性等因素对阻滑桩桩侧极限抗力及最优加固位置的影响。 相似文献
20.
《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2013,7(3-4):218-228
This paper reports the results of load and resistance factor design (LRFD) calibration for pullout and yield limit states for steel grid reinforced soil walls owing to soil self-weight loading plus permanent uniform surcharge. The calibration method uses bias statistics to account for prediction accuracy of the underlying deterministic models for reinforcement load, pullout capacity and yield strength of the steel grids, and random variability in input parameters. A new revised pullout design model is proposed to improve pullout resistance prediction accuracy and to remove hidden dependency with calculated pullout resistance values. Load and resistance factors are proposed that give a uniform probability of failure of 1% for both pullout and yield limit states. The approach adopted in this paper has application to a wide variety of other reinforced soil wall technologies. 相似文献