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1.
对坦墙墙后土体第二破裂面的研究 总被引：3，自引：0，他引：3
基于土的塑性极限分析理论，从挡土墙最小抗倾覆安全系数和挡土墙背上的最大主动土压力两个角度，分别研究了坦墙后土体中第二破裂面的位置，认为在复杂的挡土结构墙背条件下，用最小抗倾覆安全系数来研究挡土墙后土体的破坏机制较为合理。 相似文献
2.
为确定地震条件下悬臂式挡土墙主动土压力,考虑假想坦墙墙背的可能不同位置,给出了墙后填土5种可能的失稳破坏模式;在此基础上,采用拟静力法,基于极限分析上限定理,推导了作用于坦墙墙背上的地震主动土压力计算公式,包括填土性质、填方坡面倾角、踵板长度、墙体高度、水平及竖向地震影响系数等多因素,其中除填土黏聚力与竖向地震影响系数与该土压力呈线性相关性外,其余因素呈非线性影响。实例分析表明,基于本方法地震土压力而计算的墙体抗滑与抗倾稳定系数,多数情况下均比经典的Mononobe-Okabe法略偏大;在填土中存在第二破裂面情况下,以踵板下边缘作为假想墙背端点的计算模式相对略偏不安全;竖直假想墙背模式相应的土压力计算值最小,但相应的墙体稳定系数却不一定最大。 相似文献
3.
《Geomechanics and Geoengineering》2013,8(4):231-244
ABSTRACTBackfills behind retaining walls are often made of collapsible soils, which are subjected to wetting by surface running water or by rising the groundwater table. Collapsible soil shows considerable strength when it is dry or at a relatively low degree of saturation and experiences excessive and sudden settlement when it is inundated. This paper presents an experimental investigation on walls retaining overconsolidated collapsible soil subjected to passive earth pressure. A prototype model of a vertical wall, retaining horizontal backfill was developed. Collapsible soil was prepared in the laboratory by mixing kaolin clay with fine sand. The model was instrumented to measure the total passive earth force on the wall, the passive earth pressure at strategic locations on the wall, and the overconsolidation ratio of the soil in the testing tank. The state of passive pressure was developed by pushing the wall horizontally toward the backfill without any rotation. Tests were conducted on walls retaining overconsolidated collapsible soil at the dry and at full saturation conditions. Results showed that for the dry state, the passive earth pressure increases with the increase of the collapse potential and overconsolidation ratio, and was significantly dropped at full saturation. 相似文献
4.
Asadollah Ranjbar Karkanaki Navid Ganjian Faradjollah Askari 《Geotechnical and Geological Engineering》2017,35(3):1079-1092
This study presents a new algorithm for design of cantilever retaining walls based on the proposed failure mechanisms and considers the effects of wall geometric parameters using an upper-bound limit analysis approach. All previous work on this subject has only focused on the optimum design of the retaining walls assuming constant forces, irrespective of the total stability and critical conditions of failure mechanisms. In the present study, the upper-bound limit analysis method was used to determine the shape of the critical failure mechanisms for a retaining wall simultaneously with its optimal dimensions. The safety factors against overturning, sliding, and bearing capacity failure were assessed by the limit analysis approach. The current results show good agreement with the results obtained using the limit equilibrium methods and finite element analyses. The results obtained based on the proposed failure mechanism show that the geometry and dimensions of the wall affect its stability safety factors, the shape of the critical failure mechanisms and the active pressure on the wall; therefore, the process of determining the shape of the critical failure mechanisms, checking the stability of the wall and the procedure of finding its optimal dimensions should be performed simultaneously. 相似文献
5.
《Geomechanics and Geoengineering》2013,8(4):275-289
Failure of retaining walls during earthquakes has occurred many times in the past. Although significant progress has been made in analysing the seismic response of rigid gravity type retaining walls, considerable difficulties still exist in the seismic-resistant design of the flexible cantilever type of retaining walls because of the complex nature of the dynamic soil–structure interaction. In this paper the seismic response of cantilever retaining walls with dry backfill is simulated using centrifuge modelling and numerical modelling. It is found that bending moments on the wall increased significantly during an earthquake. After the end of base shaking, the residual moment on the wall was significantly higher than the moment under static loading. The numerical simulation is able to model quite accurately the main characteristics of acceleration, bending moment, and displacement recorded in the centrifuge test. 相似文献
6.
The dry‐stone retaining walls (DSRW) have been tipped as a promising solution for sustainable development. However, before recently, their behavior is relatively obscure. In this study, discrete element method (DEM) approach was applied to simulate the plane strain failure of these walls. A commercial DEM package (PFC2D™) was used throughout this study. The authors used a fully discrete approach; thus, both the wall and the backfill were modeled as discrete elements. The methodology for obtaining the micromechanical parameters was discussed in detail; this includes the three mechanical sub‐systems of DSRWs: wall, backfill and interface. The models were loaded progressively until failure, and then the results were compared with the full‐scale experimental results where the walls were loaded, respectively, with hydrostatic load and backfill. Despite its complexity and its intensive calculation time, DEM model can then be used to validate a more simplified approach. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
7.
储油罐环形加筋防护墙是由填土、筋体、格栅返包式面板组成的一个环形整体复合结构,具有明显的空间特性及其与储油罐之间复杂的相互作用,相关研究理论明显滞后于工程应用。由于环形加筋防护墙无法忽略其空间特性的影响,通过Plaxis 3D三维有限元软件进行数值模拟,采用小应变土体硬化模型作为加筋土体本构模型,研究储油罐环形加筋防护墙墙体的变形特征及加筋材料的受力特征,探讨墙体高度、厚度、墙面坡度及土工格栅刚度、加筋间距等因素对墙体变形特征的影响。结果表明:防护墙墙面侧位移随着防护墙高度、厚度和墙面倾斜角度的减小而减小,但墙体厚度过小和加筋间距过大将导致防护墙倾覆趋势增大,过小的土工格栅刚度会导致墙侧位移过大,因此需严格控制以上设计参数;加筋防护墙墙体的修筑将加大储油罐边缘处地基沉降,储油罐内燃油的装载状态不影响加筋防护墙地基沉降情况,但油罐地基最大沉降差随着储油罐内装载燃油的增多而减小;根据格栅最大拉应力位置所推测的加筋防护墙破坏面经过墙趾曲线,墙后土压力受墙面坡度影响巨大,设计时应根据坡度选择合适的设计方法。 相似文献
8.
Finite element simulations of two centrifuge tests on the same cantilever retaining wall model holding liquefiable backfill were conducted using the Biot formulation‐based program DIANA–SWANDYNE II. To demonstrate the effects due to different pore fluids in seismic centrifuge experiments, water was used as the pore fluid in one experiment whereas a substitute pore fluid was used in the second experiment. The cantilever wall model parameters were determined by comparing simulations with measurements from free‐vibration tests performed on the model wall without backfill. The initial stress conditions for dynamic analysis for the soil backfill were obtained by simulating static loads on the retaining wall from the soil backfill. Level‐ground centrifuge model results were used to select the parameters of the Pastor–Zienkiewicz mark III constitutive model used in the dynamic simulations of the soil. The effects due to different pore fluids were captured well by the simulations. The magnitudes of excess pore pressures in the soil, lateral thrust and its line of action on the wall, and wall bending strains, deflections, and accelerations were predicted well. Predictions of settlements and accelerations in the backfill were less satisfactory. Relatively high levels of Rayleigh damping were needed to be used in the retaining wall simulations in order to obtain numerically stable results, which is one of the shortcomings of the model. The procedure may be used for engineering purpose dealing with seismic analysis of flexible retaining walls where lateral pressures, bending strains and deflections in the wall are typically of importance. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
9.
This work focuses on an analysis of dry joint retaining structures based on yield design theory: the stability of the masonry is assessed using rigid block and shear failure mechanisms in the wall and its backfill. An application of this simulation on 2D scale‐down brick and wood models is then addressed, showing close agreement between theoretical predictions and experimental results. Further development on this work, including application of this theory on dry‐stone retaining walls, is discussed as a conclusion. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
10.
Wen-Chao Huang Hong-Wen Yu 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2016,10(4):269-279
In this study, the failure mechanisms for Chiuliao 1st Levee and Gueishan Levee in Taiwan were re-examined comprehensively considering the uncertainty of different parameters. Results have shown that for Chiuliao 1st Levee, the slope sliding failure has a higher coefficient of variation (COV). For Gueishan Levee, retaining wall sliding and overturning failure have higher values of COV instead. It can also be found that the scouring depths affect the stability of the levee significantly, therefore, a protecting system for the backfill material may be necessary to increase the stability of the levee effectively. 相似文献
11.
12.
For retaining walls built in mountainous regions, narrow backfill spaces are often encountered. The space to fully develop the active wedge is restricted for walls with a limited backfill space. This paper presents a numerical study on the behaviour of active earth pressures behind a rigid retaining wall with limited backfill space of various geometries. The active earth pressure for a wall built with limited backfill space is considerably less than that of the Coulomb solution, and the location of the resultant of active earth pressures is noticeably higher than one-third of the wall height. The coefficient of active earth pressures is as low as 0.5–0.6 times the Coulomb solution and the h/H value reaches up to 0.4–0.37 if aspect ratio of the fill space is in the range from 0.1 to 0.2. A clear trend between the ratio of the coefficient of active earth pressures at constrained fill conditions over the Coulomb Ka value and the aspect ratio of the fill-space geometry is obtained. 相似文献
13.
A New Pseudo-dynamic Approach for Seismic Active Soil Thrust 总被引：2，自引：0，他引：2
Ivo Bellezza 《Geotechnical and Geological Engineering》2014,32(2):561-576
A critical review of the existing pseudo-dynamic approach is provided and a new pseudo-dynamic approach is proposed based on a visco-elastic behavior of backfill overlying rigid bedrock subjected to harmonic horizontal acceleration. Considering a planar failure surface, closed form expressions for seismic active soil thrust, soil pressure distribution and overturning moment are obtained. The results of this study indicate that the existing pseudo-dynamic method can strongly underestimate the soil active thrust especially close to the fundamental frequency of the backfill, where the soil response is more sensitive to the damping ratio. The acting point of the total seismic active thrust is always found to be higher than that predicted by the traditional pseudo-dynamic approach. The effect of the shear resistance angle and wall friction angle on the acting point increases as the amplitude of the base acceleration increases, whereas their effect is generally small far from the natural frequencies of the backfill. 相似文献
14.
为研究高速公路环境与边坡填筑一体化设计关键技术,在对某高速公路段12 m高加筋边坡进行长期工作特性的现场试验研究基础上,建立考虑格栅黏弹性和土体黏弹塑性流变模型的高速公路加筋边坡数值分析模型,采用增量-初应变迭代法对各种工况进行了分析计算。通过与试验测试数据的对比,验证数值的可靠性,进而进行大量变动参数的数值分析,详细地探讨加筋边坡填筑过程中加筋结构的力学特性。在将试验数据和数值分析结果的对比分析的基础上,得到边坡加筋体内土压力、地基应力和格栅拉力分布规律及其成因,随后与类似加筋直墙和单级加筋路堤的研究结果对比,得到多级加筋陡坡的一般规律及其破坏模式。 相似文献
15.
废旧轮胎胎面挡土墙是一种有效利用废旧轮胎的理想途径,但直立的模块式废旧轮胎胎面挡土墙不能承受高强度的地震作用,因而提出格栅条带式加筋的方法提高其抗震性能。根据土-结构动力相似体系,设计格栅条带式加筋废旧轮胎胎面挡土墙振动台试验模型,考虑地震强度、地震波、格栅加筋长度、格栅加筋间距以及墙面坡度的影响,分析胎面墙体与回填料加速度、墙体侧向位移、墙顶表面回填料沉降以及墙背动土压力等地震响应特征,并与无加筋的废旧轮胎胎面挡土墙的振动台模型试验进行对比。研究结果表明:格栅条带式加筋胎面挡土墙的方式显著改善了无加筋状态的胎面挡土墙的地震响应特征,提高了胎面挡土墙的抗震性能,格栅条带式加筋直立式废旧轮胎胎面挡土墙可以作为理想的墙体进行工程推广应用。 相似文献
16.
铁路台阶式加筋土挡墙的设计方法尚不成熟,现有设计方法不能满足铁路边坡工程实践的需求。潜在破裂面的确定是加筋土挡墙设计的关键,但现行规范仅对10 m以下单级加筋土挡墙的潜在破裂面有了明确的规定。为了研究台阶式加筋土挡墙在铁路荷载作用下潜在破裂面的特征,设计了1:4的大比例尺二级台阶式加筋土挡墙室内模型试验,以周期性加卸载的方式模拟铁路荷载,通过监测墙面水平位移、墙顶沉降及土工格栅筋带变形,分析确定潜在破裂面的位置和形状。试验结果表明：I级墙（下级墙）潜在破裂面形状与现行规范中的0.3H法破裂面类似,但位置更深,且下部破裂面更缓,表明潜在不稳定范围更大;II级墙（上级墙）潜在破裂面形状与朗肯主动破裂面基本一致,但并未从II级墙坡脚剪出,而是内移刺入I级墙体;研究结果可为铁路台阶式加筋土挡墙的设计提供理论参考。 相似文献
17.
针对加筋挡墙顶部受条形基础载荷作用时的工作性能开展试验研究,分析条形基础距挡墙面板距离对基础极限承载力、加筋挡墙变形特点、筋材应变和破坏模式的影响。试验结果表明：基础极限承载力随基础偏移距离 增加呈现先增大后减小的趋势,且在 为 （ 为挡墙高度）时达到最大值;条形基础加载至破坏前一级载荷时,基础沉降与挡墙高度比值均小于2%,面板水平位移与挡墙高度比值均小于1%,且当 小于0.6时,面板顶部水平位移明显大于中底部;各层筋材中应变最大值随 增加而逐渐向远离面板方向发展,且筋材最大应变由最初出现在顶层而转向中间层;顶部受条形基础载荷作用下加筋挡墙破坏以3种模式为主,即顶层面板挤出的浅层破坏、破坏面沿基础边缘发展并向深部推进和加筋挡墙整体破坏。 相似文献
18.
Evaluation of the environmental impacts of extreme floods in the Evros River basin using Contingent Valuation Method 总被引：2，自引：1，他引：1
India is among the top ten countries with the highest percentage of landslide fatalities for the past few years. Intense rainfall during the 2009 monsoon in the hilly district of Nilgiris, in the state of Tamilnadu in India, triggered landslides at more than 300 locations which affected road and rail traffic, destroyed buildings, caused the death of more than 40 people and left hundreds homeless. In this paper, three case histories from Nilgiris district are investigated: the slope failure of a railway track at Aravankadu, failure of retaining walls supporting buildings at Coonoor, failure of the slope and retaining wall along national highway (NH67) at Chinnabikatty. Laboratory investigations are carried out on soil samples collected at these sites. Soils at all the three locations have high fine content and low values of coefficient of permeability. Finite element analyses of all the three case histories were carried out using PLAXIS2D software in order to understand the failure mechanism and contributing factors. Slope stability analysis using strength reduction technique is carried out for the slope at Aravankadu to determine the critical slip surface and factor of safety. Results reveal that the increase in pore pressures led to a reduction in shear strength of the soil and consequently resulted in progressive failure of slope at Aravankadu site. Displacement analysis is carried out for Coonoor and Chinnabikatty sites. The results show that combined effect of surcharge load of building and high pore pressure led to intense shearing behind the retaining walls at Coonoor site. Results indicate occurrence of large displacements along the face and at toe of the slope at Chinnabikatty site. 相似文献
19.
地震作用下挡土墙主动土压力及转动位移分析 总被引：2，自引：0，他引：2
分析地震引起的挡土墙位移及墙后土压力,对于评估挡土墙可靠性具有重要意义。基于拟动力法,考虑时效、地震波传播的相位差、超载、墙背摩擦角、填土黏聚力以及填土开裂等影响,建立地震作用下挡土墙主动土压力计算模型,获得挡土墙绕墙趾转动模式下主动土压力大小、分布形式及作用点高度。同时,考虑挡土墙本身受地震荷载作用的影响,求出挡土墙绕墙趾的转动位移。通过与Mononobe-Okabe法对比可知,文中获得的主动土压力值与Mononobe-Okabe法接近,但Mononobe-Okabe法低估了主动土压力作用点高度,表明采用Mononobe-Okabe法设计存在风险。通过算例分析了地震系数、墙背摩擦系数、超载大小、时间、填土黏聚力和内摩擦角对挡土墙转动位移的影响。 相似文献
20.
Aurelian Catalin Trandafir Toshitaka Kamai Roy Carl Sidle Mihail Popescu 《Geotechnical and Geological Engineering》2007,25(6):679-691
Failure of several gravity retaining walls in residential areas built on reclaimed land, during the October 23, 2004 Chuetsu
earthquake in Niigata Prefecture, Japan, determined the authorities to consider the seismic retrofit of the walls in order
to mitigate future similar disasters in the urban environment. This study addresses the effectiveness of ground anchors in
improving the seismic performance of such retaining structures through a sliding block analysis of the seismic response of
an anchored gravity retaining wall supporting a dry homogeneous fill slope subject to horizontal ground shaking. Sliding failure
along the base of the wall and translational failure along a planar slip surface of the active wedge within the fill material
behind the wall were considered in the formulation, whereas the anchor load was taken as a line load acting on the face of
the gravity retaining wall. The effects of magnitude and orientation of anchor load on the yield acceleration of the wall-backfill
system and seismically induced wall displacements were examined. It was found that for the same anchor orientation, the yield
acceleration increases in a quasi-linear manner with increasing the anchor load, whereas an anchor load of a given magnitude
acting at various orientations produces essentially identical yield accelerations. On the other hand, the computed earthquake-induced
permanent displacements of the anchored gravity retaining wall decrease exponentially with increasing magnitude of anchor
load. Additionally, the influence of backfill strength properties (e.g., internal friction angle) on the seismic wall displacement
appears to diminish considerably for the anchored gravity retaining wall. A dynamic displacement analysis conducted for the
anchored gravity retaining wall subjected to various seismic waveforms scaled to the same peak earthquake acceleration revealed
a good correlation between the calculated permanent wall displacements and the Arias intensity parameter characterizing the
input accelerogram. 相似文献