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粉砂土中PHC管桩的工作性状试验研究 总被引:8,自引:0,他引:8
采用现场标准贯入试验 ,分析了粉砂土中PHC管桩的土塞特性、不同沉桩方式对桩周土力学性能的影响。进而通过系列载荷试验 ,研究了粉砂土中PHC管桩的单桩竖向极限承载力随休止期的变化规律及时间效应。研究结果显示 ,不同沉桩方式对粉砂土中PHC管桩产生显著不同的短期时间效应 ,休止期 2 5天后单桩竖向极限承载力趋于稳定 相似文献
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Shuhei Shibayama Jun Izawa Akihiro Takahashi Jiro Takemura Osamu Kusakabe 《Soils and Foundations》2010,50(2):281-294
The paper describes observed behaviour of a model tunnel embedded in dry sand subjected to cyclic ground shear deformation in a centrifuge, as well as the behaviour of the model ground during shear deformation. Detailed data on earth pressures acting on the tunnel lining and the sectional forces of the lining are presented during ground shear deformation. The data suggest that the earth pressure at tunnel crown before ground shear deformation is smaller than the full overburden pressure probably due to the formation of arch action and the arch action may deteriorate with the cyclic ground shear deformation, resulting in an increase in the earth pressure at crown and changing the distribution of the sectional forces, which are largely influenced by conditions between tunnel lining and invert. 相似文献
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基于30个Losberg拉拔试验,对黏砂变形GFRP筋与采用箍筋约束的混凝土之间的黏结性能进行了较为系统的研究.研究表明:GFRP筋与约束混凝土之间的黏结-滑移(τ-s)曲线可分为微滑移段、滑移段、下降段、二次上升段以及残余下降段;对于采用箍筋约束的GFRP筋试件,均只发生拔出破坏,而对于无箍筋约束的GFRP筋试件,其破坏模式包括拔出和劈裂两种;与无箍筋约束的GFRP筋试件相比,GFRP筋与约束混凝土之间的黏结强度增加了0%~16%,而达到黏结强度时对应的滑移量则提高了1.20~2.76倍.在考虑GFRP筋直径、黏结长度、体积配箍率等因素的基础上,建立了GFRP筋与约束混凝土之间的黏结-滑移本构模型. 相似文献
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《Soils and Foundations》2007,47(1):1-10
Geological disposal in soft rocks is expected as one of the most practicable methods for isolation of high-level radioactive wastes. Since the country rock around the deep tunnels tends to be heated for a long term due to continuous collapse of nuclides, creep behavior of the soft rocks of impermeable nature under high temperature should be studied. Under different temperatures from 24°C to 95°C, a series of unconfined compression tests was conducted on a tuffaceous rock, Ohya stone, at creep stress ratios ranging from 0.6 to 1.0. The results show that the creep behavior is accelerated by high temperatures over 60°C. That is, for higher temperatures, the time to failure is decreased, while the minimum strain rate is increased. A creep model is then presented, in which attention is paid to the change in strain rate with time. Unique relationships between the minimum strain rate and various creep parameters are used, that appear to be dependent on neither creep stress ratio nor temperature. According to the proposed model, the creep failure will not take place if the creep stress ratio is lower than 0.44. 相似文献
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很早以前人们就发现,砂在沉积方向(竖向)的力学特性与其它方向的不同,说明砂的内部存在着各向异性的特点。近20年来,人们已经对砂内部的各向异性的影响有了一定的了解。但是,如果向砂中加入非塑性泥后,砂的力学特性又会怎样呢?人们已经观测到了泥质砂中应力-应变和液化的奇怪现象。 相似文献
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为研究风积沙混凝土与钢筋之间的黏结性能,制作了28个试块进行中心拉拔试验,研究了风积沙掺量、钢筋形状、钢筋直径和龄期对黏结性能的影响规律,并基于试验结果拟合出风积沙混凝土与带肋钢筋之间的黏结强度-滑移本构关系曲线。研究结果表明,风积沙掺量小于30%时,极限黏结强度随着风积沙掺量、钢筋直径、龄期的提高而提高;风积沙掺量分别为10%、20%和30%时,带肋钢筋对应的极限黏结强度分别比光圆钢筋提高了61.2%、58.5%、56.1%。 相似文献
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广东河砂碱活性的检测与分析 总被引:2,自引:0,他引:2
河砂的碱活性对工程结构的破坏能力至今虽然还没有定论,但其影响是不容忽视的。本文对广东的几个主要砂源(西江、东江、北江)的河砂进行了碱活性检验,发现西江河砂潜在和明显碱硅酸活性的存在几率相当高,东江河砂亦发现有潜在活性的样品,北江河砂经初步分析还不能判定是否有潜在碱—硅酸反应危害。 相似文献
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通过建立新的电化学等效电路模型,分析了海砂砂浆的碳化行为,并对新模型进行理论数学推导,得出了新模型在复平面中的曲线方程;同时通过对比分析验证了新模型的合理性.结果表明:碳化过程会引起海砂砂浆的电化学阻抗谱行为发生规律性的变化,高频圆直径随碳化龄期增大而增大;由电化学阻抗谱拟合获得的电化学模型参数具有规律性,可以定量表征海砂砂浆的碳化过程,其参数分别与碳化深度和碳化时间存在函数关系,可以对海砂砂浆的碳化深度进行预测. 相似文献
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通过微生物珊瑚砂桩单桩复合地基模型试验,研究了褥垫层厚度和桩间珊瑚砂相对密实度对微生物珊瑚砂桩单桩复合地基承载特性的影响。试验结果表明:褥垫层厚度从1 cm增加到5 cm,复合地基承载力在桩间珊瑚砂相对密实度分别为44%、56%、70%时分别提高了91.8%、45.6%、31.0%,土压力分布均匀性等也得到了改善;桩间砂相对密实度从44%增加到70%,褥垫层厚度分别为1 cm、3 cm、5 cm时复合地基承载力分别提高了121.8%、97.4%、51.5%;微生物珊瑚砂桩侧摩阻力随相对密实度增大而略有增大;微生物珊瑚砂桩侧摩阻力随深度先增大后减小,最大侧摩阻力出现在试验桩桩深10~20 cm之间;建议微生物珊瑚砂桩复合地基褥垫层厚度为0.6倍桩径。试验结果可为微生物珊瑚砂桩复合地基的工程运用提供参考。 相似文献
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Experimental data are presented in this paper to study the instability behavior of sand in strain path testing under plane-strain conditions. K0 consolidated strain path tests were conducted on Changi sand using a plane-strain apparatus. The test results show that the occurrence of pre-failure instability under plane-strain conditions is affected by the void ratio and the strain increment ratio. This is consistent with previous findings established under axisymmetric conditions. However, instability behavior of medium dense sand in strain path-controlled plane-strain tests can also be affected by shear band formation. In this case, on-failure instability takes place and failure is likely caused by shear band development. This observation is different from that in triaxial strain path-controlled tests where shear bands do not normally occur. 相似文献
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Zhang XianyU 《建筑节能》1999,(6)
利用长江粉细砂可玻化为高级饰面材料,粉细砂用量高,玻璃性能好。本文介绍了粉细砂玻璃的玻化工艺和试验结果,并对其经济效益进行了初步分析。 相似文献
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Fei Wang Linchang Miao Yajun Zhang 《Bulletin of Engineering Geology and the Environment》2012,71(2):317-324
The paper reports a study into the creep behavior of Yangtze River sand, which has implications for both the sustainability
and serviceability of structures and the prediction of land subsidence in this area. Following sieve analysis, sand was compressed
under pressures of 800, 1,600 and 3,200 kPa, with sieve analysis repeated after each test. This indicated particle crushing.
Samples were also compressed by 800 kPa for 0.5, 1, 10, and 100 min, which indicated particle breakage is associated with
creep. A new method is proposed to calculate the creep strain of Yangtze River sand, especially where laboratory test results
are not available. Two case histories are presented which demonstrate the validity of this simple method for the prediction
of post-construction settlement of a high-rise building on Yangtze River Sand and subsidence related to a pumped aquifer. 相似文献
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近年来,随着我国对海洋领土的开发,如人工造岛计划的实施,加强了对海洋资源的利用。然而海洋恶劣的气候环境、海水对岛上结构基础地基的腐蚀,对近海结构的耐久性提出了严峻的挑战。本文重点关注利用胶结材料—水泥对砂性地基处理后,地基在海水条件下动力特性的演化,将利用动三轴和共振柱试验获得全应变范围内不同侵蚀时间对人工胶结土的动剪切模量和阻尼比的影响,并对不同浸泡时间的动剪切模量给了拟合公式,同时,给出了预测水泥胶结土长期动剪切模量演化的经验公式,为工程设计提供参考。 相似文献