高温后钢管再生混凝土短柱的理论分析与试验研究   总被引：1，自引：0，他引：1  

杨有福  侯睿 《地震学刊》2012,(1):71-76

首先进行了高温后钢管再生混凝土轴压短柱的试验研究,在分析试验结果的基础上提出了高温后核心再生混凝土的应力一应变关系模型,模型考虑了再生粗骨料取代率和曾经历的最高温度的影响;然后采用数值方法对高温后钢管再生混凝土轴压短柱的荷栽一变形全过程关系曲线进行了计算分析,数值计算结果得到试验结果的验证;最后利用数值方法系统分析了再生粗骨料取代率、曾经历的最高温度和约束效应系数等参数对高温后钢管再生混凝土短柱轴压强度系数的影响,并提出了相应的简化计算公式,轴压承载力的简化计算结果与试验结果基本吻合。  相似文献   

粗粒料湿化变形数值模拟研究     

杨贵  刘汉龙  朱俊高 《地震学刊》2012,(5):535-538,551

粗粒料湿化变形特性对土石坝静力稳定有着显著影响。目前开展的三轴试验和直剪试验研究,一般只能进行干样和饱和样的试验,而对于非饱和情况研究较少。基于粗粒料不同围压下湿化变形试验研究成果开展数值模拟研究,结果表明：湿化变形的影响可以通过改变细观剪切模量和细观摩擦系数来实现;随着颗粒破碎随饱和度和围压的增加,湿化后粗粒料的强度低、内聚力降低,但摩擦角变化不大。  相似文献   

不同应力路径下绢云母片岩粗粒料声发射特征   总被引：1，自引：0，他引：1  

秦尚林  杨兰强  高惠  陈善雄 《岩土力学》2015,36(1):89-96

粗粒料在变形和颗粒破碎过程中伴随着明显的声发射（AE）,通过监测粗粒料在外力作用下的声发射信号特征可用来研究其力学机制。为探讨不同应力路径下绢云母片岩粗粒料声发射规律,采用改装设计的大型三轴试验机,对绢云母片岩粗粒料分别开展了常规三轴固结排水、等p（体应力）和等q（偏应力）应力路径试验,同时监测其声发射信号。研究表明,对于粗粒料的声发射必须考虑颗粒间的滑动摩擦、翻滚摩擦、颗粒破碎这3种细观机制。不同围压、不同应力水平对颗粒间的滑移、翻滚以及颗粒破碎活动影响较大,因此,在不同阶段,摩擦型AE与破碎型AE所占比例各不相同。在等p路径下,当累计声发射信号出现拐点时,可判断其为应变软化点。等q试验产生的累计AE计数与累计AE能量计数要比等p试验的累计AE计数和累计AE能量计数少一个量级,说明等p试验状态下的声发射要比等q试验活跃。等p试验中,随着体应力逐渐增大,累计AE参量增长率逐渐增大,而等q试验中,随着偏应力逐渐增大,累计AE参量增长率逐渐降低。  相似文献   

Analysis of shear‐dominated RC columns using the nonlinear truss analogy          下载免费PDF全文

Mohammadreza Moharrami  Ioannis Koutromanos  Marios Panagiotou  Sadik Can Girgin 《地震工程与结构动力学》2015,44(5):677-694

This paper uses nonlinear truss models for the analysis of shear‐dominated reinforced concrete (RC) columns subjected to cyclic loading. A previously established method, aimed to the analysis of RC walls, is enhanced to allow simulations of column members. The concrete constitutive equations are modified to account for the contribution of the aggregate interlock to the shear resistance. Additionally, an equation is proposed to determine the inclination angle of the diagonal members in the truss models. The modeling approach is validated using the results of quasi‐static and dynamic tests on shear‐dominated RC columns. The combination of predictive capabilities and conceptual simplicity establishes truss‐based models as an attractive approach for the systematic analysis of shear‐dominated RC frame construction. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

3D-FEM modeling of the microscopic stress field of forsterite aggregate under hydrostatic pressure: Significance of the crystal orientation     

CHEN YuXiang  LIU Xi  ZHOU YongSheng 《中国科学:地球科学(英文版)》2014,57(6):1192-1198

Three Dimensional Finite Element Method(3D-FEM)has been used to model the deviatoric stress field in a forsterite aggregate with a sandwich geometry:two forsterite cubes aligned in the same crystallographic orientation(the"breads")sandwich a third forsterite cube(the"filling"),which might have an identical or different crystallographic orientation.The results show that there is no von Mises stress in the forsterite sandwich if the sandwiching and sandwiched forsterite cubes are aligned in the same crystallographic orientation.If the crystallographic orientations are different,however,von Mises stress and heterogeneous stress distribution occur both along the boundary and in the forsterite cubes.For the investigated P-T conditions(up to 6.4GPa and 500°C),the resulted deviatoric stress is much lower than the yield strength of forsterite,so that higher P,higher T,or other means to create higher deviatoric stress is necessary,in order to constrain the yielding behavior of forsterite.  相似文献   

A laboratory study on the kinetics of the formation of oil-suspended particulate matter aggregates using the NIST-1941b sediment     

Juan Sun  Ali Khelifa  Zhendi Wang  Sharon Wong  Benjamin Fieldhouse 《Marine pollution bulletin》2010,60(10):1701-1707

The formation of oil-suspended particulate matter aggregates (OSAs) results from the heteroaggregation between dispersed oil droplets and suspended particulate matter present in coastal waters. This process has been recognized by the oil spill remediation community to enhance natural cleansing of oiled shorelines and oil dispersion in the water column. While several studies have been conducted on the formation and characteristics of OSAs, few studies have addressed the kinetics of OSA formation. Operationally, this has left decision-makers lacking information on the time scale of this process and its significance to oil dispersion in real spills. A laboratory study was conducted to investigate the kinetics of OSA formation as a function of mixing energy and the sediment-to-oil ratio using the standard reference material 1941b. Results showed that formation of OSAs increased exponentially with the mixing time and reached a maximum within 4 h. When the shaking rate increased from 2.0 to 2.3 Hz, the maximum oil trapping efficiency increased from 20% to 42% and the required shaking time decreased from 3.7 to 0.7 h.  相似文献   

不同级配粗颗粒材料动力特性试验研究     

傅华  赵大海  韩华强  凌华 《岩土力学》2016,37(8):2279-2284

级配是粗颗粒材料最基本特征,根据大量试验结果和长期积累的试验经验,总结出了试验级配缩制的具体原则,并基于粗颗粒材料中小于等于5 mm粒径含量变化,分析了级配优劣对其充填关系的影响,级配越优,粗颗粒材料的充填关系越好,粗颗粒材料能达到较大的干密度,反之则越差,粗颗粒材料也难以获得较大的干密度。级配的优劣对堆石料动力特性的影响在低围压状态下并不明显,随着围压的升高,级配优的堆石料动力特性指标明显变优;砂砾料由于颗粒浑圆度较好,级配的优劣对其动力特性的影响逐渐减弱。针对上述级配对粗颗粒材料动力特性的影响规律,对于高土石坝来说有必要采用级配优的粗颗粒材料作为坝体的填筑料,通过其在高应力条件下力学性能的优势来控制坝体整体变形和提高其抗震性能。  相似文献   

Accumulative deformation in railway track induced by high-speed traffic loading of the trains   总被引：1，自引：0，他引：1  

Xuecheng Bian  Hongguang Jiang  Yunmin Chen 《地震工程与工程振动(英文版)》2010,9(3):319-326

Prediction and control of the permanent settlement of a track caused by traffic loading from trains is crucial to high-speed railway design and maintenance. In this study, a unified prediction model of accumulative deformation of geomaterials used in railway construction subjected to cyclic loadings is introduced and calibrated using physical model testing. Based on this versatile model, a calculation approach to determine the track structure settlement under repeated loadings caused by the movement of the wheel axle of the train is proposed. Regression analysis on the physical model testing is adopted to determine the parameters involved in the computational approach. Comparison of model test data and computed results shows that the parameters obtained from the back-analysis are consistent throughout the various testing conditions, and the proposed calculation approach is capable of satisfactorily predicting the accumulative settlement of the railway roadbed and subgrade soil for various axle loads and loading cycles. A case study of a high-speed railway is performed to demonstrate the feasibility of the proposed approach in realistic engineering applications. The computation results from the settlement development of a roadbed and subgrade soil are presented and discussed.  相似文献   

Studies on soil organic carbon of density-isolated fractions and water-stable aggregates under different types of land use on black soils     

Haibo LI Xiaozeng HAN Feng WANG Yunfa QIAO Baoshan XING 《中国地球化学学报》2006,25(B08):266-267

The experiment was conducted to determine the organic carbon concentrations of black soils by using density fractionation and wet-sieving of aggregates into five size fractions. Soil samples （0-20 cm layer） were collected from the following experiment sites （National Field Research Station of Agro-ecosystem in Hailun, Northeast of China）： （1） grassland （GL）, formerly cropped, and but fallowed in 1985 with Leymus chinesis as the dominant species; （2） bareland （BL）, like grassland, fallowed in 1985, but grasses were eliminated periodically during the plant growth stages; （3） cropland, three treatments in a long-term site experiment established in 1993 were selected, including no fertilizer applied （NF）, nitrogen and phosphorus fertilizers applied （NP）, and NP fertilizer amended with organic materials （NPOM）. The results showed that the total organic carbon （TOC） concentrations within five experiment sites differed significantly at P〈0.01. The natural ecosystem subjected to human disturbance or transferred into cropland resulted in loss of TOC, however, TOC concentrations increased significantly with chemical fertilizer plus organic manure incorporated into cropland. The OC concentrations in the free light fraction （free-LF） and heavy fraction （HF） had significant correlations with those of TOC in the whole soil at P〈0.01, which indicated that the accumulation of free-LF and HF was very important for the net increase in the TOC. In GL more than 90% of the aggregate separates was larger than 0.25 mm, in which aggregates larger than 2 mm accounted for 44%, as a result of physical enmeshing of fine roots.  相似文献   

红矸石在锚喷支护巷道中的应用          下载免费PDF全文

刘玉元  李瑞江  张京泉 《探矿工程》2006,33(2):63-65

通过对矿井锚索支护巷道喷浆骨料的各种配比试验研究，结合现场的实际应用，总结出比较适合巷道喷浆使用的采用红矸石做骨料的骨料配比方案。  相似文献