中印两国钢筋混凝土桩竖向承载能力计算方法对比

根据笔者在印度西孟加拉邦SAGARDIGHI THERMAL POWER PLANT(2*300MW)主厂房工程桩基处理方案的谈判和实践经验,介绍中国和印度两国在钢筋混凝土桩竖向承载能力确定时采用的计算方法和结果的对比分析,供有机会参与印度工程项目设计的设计人员参考和借鉴.     

大型整体式贮煤筒仓结构设计中的几个问题

对大型整体式贮煤筒仓结构设计中的几个问题进行了讨论与分析,这些问题包括:(1)堆煤引起的内外温度差以及煤压力的取值;(2)温度荷载和煤压力荷载对筒壁内力分布的影响规律;(3)堆煤荷载对桩基内力的影响.分析结果表明:对于筒壁环向受力来说,内外壁温差和煤压力的组合是控制工况,其内力为拉、弯组合;对于竖向受力来说,下部由堆煤压力单独作用控制,中上部也由内外壁温差和煤压力的组合工况控制,其内力为压、弯组合;季节温升或温降的影响较小,可以不考虑;受堆煤区煤压力的作用,基础土体产生较大的沉降和水平径向位移,使得承台下内侧桩受到较大的负摩擦力和水平推力,从而产生较大的轴力和弯矩,设计时必须引起足够的重视.     

大口径钻孔灌注桩的孔壁稳定研究分析

从钻孔灌注桩钻孔过程来看,由于地层土压力、孔隙水压力、地下水位及土体的蠕变等因素的影响,在成孔过程中或混凝土浇筑之前,孔壁处于不稳定状态之中,随时会出现滑裂或坍塌的危险。结合重阳大桥钻孔灌注桩工程,在分析孔壁稳定条件的基础上,进行不同土层的钻孔孔壁稳定性分析,同时分析孔内泥浆的稳定护壁作用及功能,建立孔壁稳定性数学分析模型,提出相应的护壁措施,防止孔壁的坍塌。     

钢护筒混凝土灌注桩的基础抗震性能研究进展

深水桥梁基础施工时的钢护筒在钻孔灌注桩施工完毕后保留,桩体实际上形成了上大下小的变截面混合桩。利用钢护筒参与桩身受力来改善基础的抗震性能,具有高效、简便且又经济的突出特点,有广泛的应用前景。本文针对目前钢护筒混凝土灌注桩的应用、研究现状、钢护筒混凝土桩和钢管混凝土桩的区别以及钢护筒混凝土灌注桩的基础抗震性能研究存在的问题等进行了总结与归纳,并提出一些建议。为钢护筒混凝土灌注桩的进一步研究提供参考。     

南水北调潴龙河倒虹吸振冲碎石桩施工与检验

通过水利工程实例,介绍了振冲碎石桩的施工原理、施工流程、常见问题、处理措施及桩体质量检测方法,数据详实,方法得当,对施工起到了很好的指导作用。施工完成后,经过处理的地基承载力提高比较明显,施工效果较好,为类似工程施工提供了借鉴。     

SCC modification by use of amorphous nano-silica

In this study two different types of nano-silica (nS) were applied in self-compacting concrete (SCC), both having similar particle size distributions (PSD), but produced through two different processes: fumed powder silica and precipitated silica in colloidal suspension. The influence of nano-silica on SCC was investigated with respect to the properties of concrete in fresh (workability) and hardened state (mechanical properties and durability). Additionally, the densification of the microstructure of the hardened concrete was verified by SEM and EDS analyses. The obtained results demonstrate that nano-silica efficiently used in SCC can improve its mechanical properties and durability. Considering the reactivity of the two applied nano-silicas, the colloidal type showed a higher reactivity at early age, which influenced the final SCC properties.     

Improvements in Quality of As-Manufactured Fuels for High-Temperature Gas-Cooled Reactors

The mechanisms of coating failure of the fuel particles for the high-temperature gas-cooled reactors during coating and compaction processes of the fuel fabrication were studied to determine a way to reduce the defective particle fraction of the as-manufactured fuels. Through the observation of the defective particles, it was found that the coating failure during the coating process was mainly caused by the strong mechanical shocks to the particles given by violent particle fluidization in the coater and by unloading and loading of the particles. The coating failure during the compaction process was probably related to the direct contact with neighboring particles in the fuel compacts. The coating process was improved by optimizing the mode of the particle fluidization and by developing the process without unloading and loading of the particles at intermediate coating process. The compaction process was improved by optimizing the combination of the pressing temperature and the pressing speed of the overcoated particles. Through these modifications of the fabrication process, the quality of the as-manufactured fuel compacts was improved outstandingly.     

软弱土层基坑水泥搅拌桩止水帷幕失效分析

以广州市某基坑工程止水帷幕失效为背景,对软弱土层地质条件下的城市深基坑水泥搅拌桩止水帷幕失效原因进行了分析。土体中的有机质含量、固化剂的比例及桩体有效入土深度等因素对水泥搅拌桩的成桩质量和止水效果有较大影响。城市深基坑通常施工场地比较狭窄,基坑的支护结构、电梯井基坑、降水及其他工程对水泥搅拌桩的施工质量有时也会产生较大影响,因此应做好相应的设计和施工管理工作。     

生石灰桩加固既有建筑物湿陷性黄土地基试验研究及工程应用

采用生石灰桩加固湿陷性黄土地基是工程中常用的手段,但对于生石灰桩的体积膨胀系数和吸水率工程中常利用经验取值.为了进行更深入的研究,本文结合实际工程,通过固结仪分析了生石灰桩在不同土压力下的膨胀和吸水特性,得出了特定条件下生石灰桩体积膨胀系数及吸水率与深度的关系,进而得出了生石灰桩的平均体积膨胀系数和平均吸水率,从而为不...     

碎石桩处理软土地基技术在菲律宾北吕宋铁路的成功应用

通过介绍碎石桩加固软基在菲律宾北吕宋铁路项目一期一段的成功应用,为中国企业在海外施工探讨了新的思路.