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1.
The interaction between geogrid and soil is crucial for the stability of geogrid-reinforced earth structure. In finite element (FE) analysis, geogrids are usually assumed as beam or truss elements, and the interaction between geogrid and soil is considered as Coulomb friction resistance, which cannot reflect the true stress and displacement developed in the reinforcement. And the traditional Lagrangian elements used to simulate soil always become highly distorted and lose accuracy in high-stress blocks. An improved geogrid model that can produce shear resistance and passive resistance and a soil model using the Eulerian technique, in combination with the coupled Eulerian-Lagrangian (CEL) method, are used to analyze the interaction between geogrid and soil of reinforced foundation test in ABAQUS. The stress in the backfill, resistance of geogrid, and settlement of foundation were computed and the results of analysis agree well with the experimental results. This simulation method is of referential value for FE analysis of reinforced earth structure. 相似文献
2.
Environmental effects induced by excavation 总被引：1，自引：0，他引：1
Based on 3D Biot＇s consolidation theory and nonlinear Duncan-Chang＇s model, a 3D FEM （finite element method） program is developed considering the coupling of groundwater seepage and soil skeleton deformation during excavation. The comparison between the analysis result considering the variation of water head difference and that without considering it shows that the porewater pressure distribution of the former is distinctly different from that of the latter and that the foundation pit deformations of the former are larger than those of the latter, so that the result without considering the variation of water head difference is unreliable. The distribution rules of soil horizontal and vertical displacements around the pit and excess porewater pressure are analyzed in detail in time and space, which is very significant for guiding underground engineering construction and ensuring environment safety around the pit. 相似文献
3.
On the dissipation of negative excess porewater pressure induced by excavation in soft soil 总被引：3，自引：0，他引：3
INTRODUCTION Since Terzaghi founded his one-dimensionalconsolidation theory, the studies on consolidation ofsoft soil have been made by many researchers (Gray,1945; Gibson et al., 1967; 1981; Schiffman and Stein,1970; Xie, 1994; Xie et al., 2002a). However, al-though as we all know, negative excess porewaterpressure will be induced by unloading in excavation,the dissipation of the negative pressure and its effectsare rarely studied because of their complexity (Chenand Wen, 1999; … 相似文献
4.
黄伟达 《福建工程学院学报》2012,10(6):567-570
在高陡填方区采用土工格栅加筋土挡墙,容易产生较大变形,且至变形稳定持续时间长。文章以某填方边坡为例,对无面板式加筋土挡墙的变形性状进行分析,分析结果表明,无面板式高陡加筋土挡墙的大变形,主要是地质条件、填料及土工格栅材料、施工条件、面板等综合影响。基此,提出了防患加筋土挡墙变形的相应建议。 相似文献
5.
基于库仑土压力理论,通过研究刚性挡墙绕墙顶转动极限状态土体内主应力拱形状,推导了侧土压力系数和水平微分单元间摩擦系数的理论公式,进而得到改进的主、被动土压力计算公式,并用模型试验结果验证。研究表明:考虑土拱效应计算结果与模型试验结果吻合比较好,墙土摩擦角越大,土拱效应越显著,主动土压力合力作用点越往上移,被动土压力合力作用点越往下移。 相似文献
6.
本文分析了运用库仑土压力理论计算回填土墙的土体侧压力的计算值与实际值之间产生误差的原因，并根据实际测试结果提出了库仑土压力计算公式的修正系数，从而使得设计的计算结果与实际结果相一致。 相似文献
7.
隋智力 《北京城市学院学报》2014,(1):92-97
本文以北京三峡大厦深基坑开挖支护为工程背景,结合理论分析、现场监测和数值模拟等方法,对钢管复合土钉墙支护的作用机理和应用效果进行了研究。根据土力学和基坑支护相关原理确立力学机理模型,采用有限差分数值模拟方法进行开挖支护模拟,将数值模拟结果与实测基坑变形数据进行分析比较,二者结果基本一致,说明数值模拟方法应用于基坑开挖支护过程是比较可靠的,且从塑性区和变形分析可知用钢管桩复合土钉墙进行支护后的基坑是稳定的,即钢管桩复合土钉墙能很好地满足基坑支护稳定性的要求。 相似文献
8.
Buckling design of large steel silos with various slendernesses 总被引：1，自引：0，他引：1
Large steel silos are typical kinds of thin-walled structure which are widely used for storing huge quantities of granular solids in industry and agriculture. In the present analyses, the buckling design of large steel silos subject to Eurocode-specified solid pressure is demonstrated. The finite element model is established using the commercial general purpose computer package ANSYS. Six types of buckling analyses are carried out for the geometrically perfect and imperfect models with and without consideration of material plasticity. The load cases of concentric discharge, discharge patch load, large eccentricity discharge, and large eccentricity filling are considered. The buckling behavior of six example steel silos with capacities of 30 000–60 000 m3 is investigated. The silos’ slenderness ranges from 4.77 to 0.35, comprising very slender, slender, intermediate slender, squat, and retaining silos. The index called the ratio of capacity to steel consumption (RCS) is initially defined in the paper, which provides an effective measure for the economical design of steel silos. It is validated that the RCS index increases rapidly with the decrease of silo slenderness, and the storage efficiency of steel silo improved greatly as the slenderness changes from slender silo to retaining silo. The effects of patch load reveal that the buckling modes in the case of discharge patch load are very different from those of silos under concentric solid pressure, and the effect is unfavorable for buckling resistance of all levels of slenderness of the example silos, but contributes a small decrease to the RCS index (less than 10%). The buckling deformations from both the linear and nonlinear buckling analyses in large eccentric discharge are strongly asymmetrical arising from the circumferential and meridional non-uniform distribution of the solid pressures. The buckling is mainly governed by the non-uniform distribution of the solid pressure other than other influential factors such as the weld imperfection, geometrical and material nonlinearity, compared with the load case of concentric discharge. The RCS index of example silos under large eccentric discharge is reduced substantially, and is approximately half that of silos under concentric discharge. The linear and nonlinear buckling deformations in large eccentric filling are also asymmetrical, deviating from the center to the side where the most friction locates to the highest wall contact. The RCS index of example silos under large eccentric filling is also reduced substantially, and is approximately 70% that of silos under concentric discharge. This reveals that the large eccentricity both in discharging and filling could result in a strong decrease of storage efficiency of steel silos. 相似文献
9.
为分析基坑内侧土体加固对支护结构水平位移的影响规律,将加固体及未加固土体视为复合土体,以弹性地基梁法为基础建立支挡结构的杆系有限元模型,结合工程实例计算分析土体加固参数对支护结构水平位移的影响。结果表明,支护结构水平位移随加固深度的增加而减小,且存在临界深度。当加固体的水泥掺量在0～15%范围内增加或置换率在0～0.5范围内增加,支护结构水平位移显著减小,加固效果显著;当水泥掺量大于15%或置换率大于0.5,支护结构水平位移变化较小,加固效能降低。 相似文献
10.
潘天能 《淮北职业技术学院学报》2008,7(5):17-18
桥头跳车是公路工程八大通病之一,笔者结合宣（城）广（德）高速公路在桥涵台背、挡墙两侧回填的特殊方法,浅析解决桥头跳车的预防措施和治理对策。 相似文献
11.
XIAO Cheng-zhi LUAN Mao.tian YANG Qing PEI Jian-jun 《重庆大学学报(英文版)》2005,4(3):139-143
1 Introduction 1 The sheet type geogrids, which are characterized by grid structures with apertures of (10 to 100) mm between longitudinal and transverse ribs respectively are made from pre-extruded high density polyethylene sheets by punching and drawing process, and the drawing process forms the structures of grid and enhances the tensile strength of geogrids to a grea extent. Since the geogrids possess high tensile strength in nature, they are widely used as reinforcement in segmental retai… 相似文献
12.
《天津大学学报(英文版)》2015,(4)
A series of model experiments of bucket foundations concerning suction installation and negative pressure consolidation in saturated silt were carried out in a cube steel bin at Tianjin University. The experimental results show that the silt inside the bucket has been strengthened by negative pressure, and the strengthening effect decreases with the increase of the distance from the bucket. A three-dimensional numerical model of the experiments was built by means of finite element software ABAQUS with fluid-solid coupling method. The results show that the bearing capacity of the silt inside the bucket foundation increases significantly at the former stage of negative pressure consolidation, while the increasing trend slows down over time. The rotation centers of the bucket foundation and the inner soil region tend to be closer to each other based on the consolidation. The bearing capacity of the bucket foundation is improved effectively with the increase of soil strength. The effects of negative pressure consolidation on the bearing capacity of bucket foundation were also illustrated by an actual offshore wind power project case. 相似文献
13.
以湖岸支护工程为例,基于有限元模拟研究了支护结构内力及变形、地表沉降、基坑隆起以及土压力分布情况,探讨了桩顶锚固形式和板桩嵌固深度,得到板桩-冠梁协同支护体系工作机理。 研究表明:板桩-冠梁协同支护体系的桩土协同作用机制与有锚板桩相似,桩体变形呈现中部鼓出状,主动土压力呈R 形分布;桩顶冠梁锚固以及桩底嵌固作用是影响板桩支护性能的重要因素,板桩最佳嵌固深度比为0.69~0.79。 研究成果可为相关板桩支护的设计和工程应用提供参考借鉴。 相似文献
14.
林智勇 《福建工程学院学报》2016,(4):318-323
利用数值分析方法建立了软土地基模型,采用比奥固结理论,计算分析了真空预压下的软土地基流固耦合作用;并进一步分析了真空度损耗率、密封墙、塑料排水板打设深度等因素对软基加固效果的影响。分析结果表明:在抽真空早期,地表沉降增长很快,达到一定天数后,沉降值逐渐趋于稳定;真空负压沿深度、水平方向上损耗,在加固软土外围形成一个零孔隙水压力面;真空度损耗率、塑料排水板打设深度对真空预压加固软土的效果影响很大;侧向密封墙对加固区内土体影响不大,但其限制了真空负压的侧向传递,使影响区的地基沉降大幅减小。 相似文献
15.
为探究无支撑多级支护结构的不同设计参数对基坑变形的影响,以一个无支撑两级支护的粉质黏土深基坑为例,利用FLAC3D软件建立数值模型,并基于正交试验通过极差、方差分析,就两级支护间距、开挖比以及两级支护结构长度对支护结构位移的影响进行研究。主要结论如下:采用无支撑两级支护结构的粉质黏土深基坑,两级支护结构的顶部最大位移受两级支护间距和开挖比影响的敏感度较高两级支护结构位移之间存在“叠加作用”、“牵引作用”的相互影响,但当两级支护间距不小于总开挖深度的0.5倍时,相互影响不显著当两级支护间距不小于总开挖深度的0.5倍,且开挖比为0.8~1.3时,两级支护结构的顶部最大位移比较接近,且不超过规范的一级基坑下限控制值,处于最合理的工作状态。 相似文献
16.
火映霞 《江苏广播电视大学学报》2006,17(6):65-67
应用P laxis有限元程序对内撑式围护结构基坑的开挖过程进行二维数值模拟分析,研究不同的开挖方式对于地表沉降、基底隆起、挡墙位移的影响,对比分析得出“先撑后挖”的开挖方式较为合理,对基坑工程施工具有积极的指导意义。 相似文献
17.
U型钢筋混凝土地道桥的受力计算比较复杂,涉及到挡土墙土压力计算的水土分算和水土合算,本文通过大型有限元软件ANSYS,建立U型钢筋混凝土地道桥的有限元模型和力学模型,对其进行三维有限元荷载应力分析。 相似文献
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19.
张实斌 《辽宁科技学院学报》2010,12(3):15-16
文章探讨了采用箱型重力式挡土墙处理15m～20m高挡土墙的问题,克服了传统挡土墙应用的局限性,利用挡土墙箱内的填土来平衡外部土体压力,既减小了结构构件的截面尺寸又相应增加了重力式挡土墙的适用高度。 相似文献
20.
Numerical Analysis of Soil Plug Inside Suction Foundations During Suction Penetration by Discrete Element Method 总被引：2，自引：1，他引：2
The phenomenon of the soil plug usually rising inside the suction foundations during suction penetration was quantitatively described and predicted. The formation process of the soil plug was simulated and calculated by DEM （discrete element method） model. The seepage flow, the self-weight of soil, the friction on the chamber wall as well as the suction inside the chamber are considered as the main external forces in the process. The results are compared with a set of laboratory model tests performed by using three soil types （sand, silty clay and clay） in the Bohai Sea area. The heights of soil plug from numerical estimations are lower than those from model test results, mainly because the suction pressure and friction resistance are applied in an ideal way under the numerical simulation. 相似文献