苏通长江大桥北引桥二期试桩试验研究   总被引：1，自引：0，他引：1  

黄生根  龚维明 《工程地质学报》2005,13(1):107-112

苏通长江大桥北引桥二期试桩工程采用自平衡试桩法对4根桩进行了测试,其中2根采用U管桩端压浆技术。根 据未压浆桩端阻实测值与计算结果的比较,计算值偏大,实测值为计算值的0.75～0.95倍。未压浆桩发挥端阻所需位移分别 为16mm、38mm,压浆桩发挥端阻所需位移有所减少,分别为12mm、21mm。压浆后桩端阻力测试值是未压浆桩端阻力测试值 的2.46～3.32倍,是规范计算值的2.46～2.50倍。压浆后,桩端阻力在总荷载中所占比例明显提高,由14.42%～15.39%提 高到22.83%～27.22%。桩端压浆对桩侧摩阻力有较大影响,其显著影响范围约为桩端以上14.27m～19.12m,且发挥摩阻 力所需位移明显减小。  相似文献   

Bearing capacity of ring footings on cohesionless soil under eccentric load     

《Computers and Geotechnics》2017

This paper presents a study on the bearing capacity of eccentrically-loaded rough ring footings resting over cohesionless soil. To this aim, a series of 3D numerical simulations were performed using the finite difference method. In order to consider the effect of load eccentricity, reduction factor method is applied. In this method, the ratio of an eccentrically-loaded bearing capacity to the bearing capacity of the same footing under vertical load is defined. Comparison between the results of the numerical simulations with those of analytical solutions and experimental data indicates good agreement. A mathematical expression is also introduced for eccentrically-loaded ring footings.  相似文献   

Numerical study of the bearing capacity for two interfering strip footings on sands     

A. Mabrouki  D. Benmeddour  R. Frank  M. Mellas 《Computers and Geotechnics》2010

Current studies of bearing capacity for shallow foundations tend to rely on the hypothesis of an isolated footing. In practice a footing is never isolated; it is mostly in interaction with other footings. This paper focuses on a numerical study using the finite-difference code Fast Lagrangian Analysis of Continua (FLAC), to evaluate the bearing capacity for two interfering strip footings, subjected to centered vertical loads with smooth and rough interfaces. The soil is modeled by an elasto-plastic model with a Mohr–Coulomb yield criterion and associative flow rule. The interference effect is estimated by efficiency factors, defined as the ratio of the bearing capacity for a single footing in the presence of the other footing to that of the single isolated footing. The efficiency factors have been computed individually to estimate the effects of cohesion, surcharge, and soil weight using Terzaghi’s equation, both in a frictional soil with surcharge pressures and in a cohesive-frictional soil with surcharge pressures. The results have been compared with those available in the literature.  相似文献   

Reliability analysis of the bearing failure problem considering uncertain stochastic parameters     

Thomas Most  Tina Knabe 《Computers and Geotechnics》2010

The consideration of uncertainties plays an increasing role in the design of geotechnical structures. An important procedure in the uncertainty analysis is the reliability assessment whereby the required statistical quantities and distributions are assumed to be known exactly. Due to small sample observations and missing information this is not the case in practical applications and uncertainties in the stochastic parameters themselves have to be considered. In our study we estimate the parameter variation of soil properties by statistical procedures and perform an extended reliability analysis of a shallow foundation considering these uncertainties. We propose a novel approach based on a Taylor series expansion which enables the estimation of the failure probability variation very efficiently.  相似文献   

陆相断陷盆地储层地震预测技术优化     

王长江  穆星 《上海国土资源》2010,31(Z1)

陆相断陷盆地是我国油气资源重要的聚集地,盆地具有复杂多样的沉积体系和储集类型。在济阳坳陷勘探实践中,逐步形成了针对不同类型储集体的地震地质综合研究技术系列。但随着勘探程度的提高,储层预测技术的精度和可靠度急需进一步深化。针对这一问题并结合现阶段主要勘探目标,本文提出了一套针对性的技术优化手段,形成了定量统计分析明确目标地震地质特征;探井成败研究找出问题关键;适用条件评价发展有效解决方法;多学科综合分析降低勘探风险的储层精细预测技术流程,在实际油气勘探实践中取得了显著的应用效果。  相似文献   

粮食增产背景下松花江区水资源承载力分析   总被引：4，自引：1，他引：3  

张士锋  孟秀敬 《地理科学》2012,(3):342-347

松花江区是中国粮食增产计划的重点地区,这势必对该区的水资源开发利用提出挑战。建立研究区水资源承载力的综合评价模型,选取社会经济指标、用水指标、水土资源对人口的承载指标、水资源供需指标和水环境等5类共10项指标组成评价指标体系,采用聚类分析、层次分析和模糊矩阵的方法进行计算。以2007年作为现状年,1999年为参照年份,得到各年份水资源承载力整体均处于安全状态的结论;结合研究区具体情况对水资源承载力的影响因素进行分析,预测粮食增产条件下研究区水资源承载力的变化趋势。  相似文献   

建筑工程中膨胀土浸水软化及承载力试验     

蔡春 《云南地质》2005,24(3):313-316

工程地基膨胀土浸水软化后,各项力学指标均有较大变化,承载力则明显衰减,设计和施工中应慎重对待.  相似文献   

Behaviour of model footing on pond ash     

Ashis Kumar Bera  Ambarish Ghosh  Amalendu Ghosh 《Geotechnical and Geological Engineering》2007,25(3):315-325

This paper focuses on the effective utilization of pond ash, as foundation medium. A series of laboratory model tests have been carried out using square, rectangular and strip footings on pond ash. The effects of dry density, degree of saturation of pond ash, size and shape of footing on ultimate bearing capacity of shallow foundations are presented in this paper. Local shear failure of a square footing on pond ash at 37% moisture content (optimum moisture content) is observed up to the values of dry density 11.20 kN/m³ and general shear failure takes place at the values of dry density 11.48 kN/m³ and 11.70 kN/m³. Effects of degree of saturation on ultimate bearing capacity were studied. Experimental results show that degree of saturation significantly affects the ultimate bearing capacity of strip footing. The effect of footing length to width ratio (L/B), on increase in ultimate bearing capacity of pond ash, is insignificant for L/B ≥ 10 in case of rectangular footings. The effects of size of footing on ultimate bearing capacity for all shapes of footings viz., square, rectangular and strip footings are highlighted.  相似文献   

强柱系数基于结构易损性的抗震性能评估          下载免费PDF全文

周靖  蔡健  方小丹 《地震工程学报》2007,29(3):207-212

增大柱端抗弯承载力是抗震"能力设计"措施中引导钢筋混凝土框架结构形成梁铰型有利耗能机构的关键措施。本文以6层确定性钢筋混凝土框架结构为分析对象,通过结构易损性分析评估了不同强柱系数取值对钢筋混凝土框架结构抗震性能的影响。结构易损性分析表明增大柱端抗弯承载力是改善结构抗震性能的有效措施,增大强柱系数提高了结构的变形能力,使不同破坏极限状态之间形成较大的"梯度",对防止强烈地震作用下结构的突然倒塌提供了预示。结构易损性曲线对评估结构抗震性能、选用合适的目标强柱系数提供了量化标准。  相似文献   

Assessment of liquefaction triggering using strain energy concept and ANN model: Capacity Energy   总被引：3，自引：0，他引：3  

M.H. Baziar  Y. Jafarian   《Soil Dynamics and Earthquake Engineering》2007,27(12):1056-1072

In the present study, an artificial neural network (ANN) model was developed to establish a correlation between soils initial parameters and the strain energy required to trigger liquefaction in sands and silty sands. A relatively large set of data including 284 previously published cyclic triaxial, torsional shear and simple shear test results were employed to develop the model. A subsequent parametric study was carried out and the trends of the results have been confirmed via some previous laboratory studies. In addition, the data recorded during some real earthquakes at Wildlife, Lotung and Port Island Kobe sites plus some available centrifuge tests data have been utilized in order to validate the proposed ANN-based liquefaction energy model. The results clearly demonstrate the capability of the proposed model and the strain energy concept to assess liquefaction resistance (capacity energy) of soils.  相似文献