深水单层钢板桩围堰设计与分析

钢板桩围堰由于具有施工速度快、防水性能好、可重复利用等诸多优点,被广泛应用于各种永久性和临时性工程,包括港口、码头、河道护岸、挡土墙、地下结构、桥梁承台围堰等工程中.某桥梁承台工程在水深近10m的河道中,采用单层钢板桩围堰施工,应用MIDAS/Civil三维结构软件建立力学模型,对钢板桩进行强度和刚度计算,验算钢板桩的实际受力及支护结构的稳定性,以确保支护结构的精确性和安全性.从而达到满足工程施工需要,节省投资,缩短工期,提高社会经济效益的目的.     

静压管桩静载试验分析

采用在预应力管桩中预埋应力计测桩身轴力的现场试验方案,在静压桩贯入过程中测得桩身轴力,并进行了竖向抗压静载试验,测得不同分级荷载作用下的桩身轴力图,通过对桩身内力分析来研究管桩在压桩及静载试验过程中的受力机理。     

黄河三角洲改性含盐水泥土搅拌桩耐久性研究

通过室内试验,研究了黄河三角洲含盐水泥土的劣化规律以及粉煤灰和矿渣微粉对其劣化的抑制效应,并利用X射线衍射（XRD）和扫描电镜（SEM）对劣化机理及外加剂的改性机理进行了分析.结果表明：地下盐水环境对黄河三角洲水泥土有较强的腐蚀作用,其90,180d龄期的抗压强度分别降低了18.5%,21.6%;掺加粉煤灰对黄河三角洲含盐水泥土的早期强度不利,但其后期强度会持续增加;掺加矿渣微粉对黄河三角洲含盐水泥土强度有明显的提升作用,并对其劣化有显著的抑制作用.为防止黄河三角洲含盐水泥土劣化,工程中建议用粉煤灰和矿渣微粉等质量替代60%的水泥,而且矿渣微粉掺量不少于40%.     

Centrifuge modeling of hybrid foundation to mitigate liquefaction-induced effects on shallow foundation resting on liquefiable ground

A hybrid foundation is developed in this study to mitigate the liquefaction-induced effects on shallow foundations. The proposed hybrid foundation is a combination of a gravel drainage system and friction steel piles with spiral blades, framed under the footing. The motivation behind having a gravel drainage system, as an integral part of the hybrid foundation, is its ability to improve the liquefaction resistance of the ground in the most economical way. However, case histories and the development of recent research have highlighted that gravel drainage systems have exhibited poor performances and could not prevent ground liquefaction during strong ground motion. To counteract these shortcomings, friction steel piles are provided which are supposed to yield frictional resistance during earthquakes and are presumed to minimize the rocking/tilting behavior of the foundation-structure system even if the ground undergoes liquefaction. The evolution of excess pore water pressure, specifically in the vicinity of the foundation-structure system, dominatingly influences the settlement mechanism of shallow foundations. Centrifuge test results show that the presence of gravel drainage can minimize the post-liquefaction settlement of shallow foundations through the rapid dissipation of excess pore water pressure. Moreover, friction piles are able to minimize the tilting/differential settlement of shallow foundations. It is found that the proposed hybrid foundation provides the desired function of reducing the overall liquefaction-induced effects on shallow foundations resting on liquefiable grounds.     

低应变瞬态荷载作用下基桩动力响应解析解

目前广泛采用的基桩低应变检测问题的理论基础是基于平截面假定的一维应力波理论。而实际上,锤击产生的应力波是三维应力波,不仅沿桩身纵向传播,还沿径向传播,对于基桩低应变检测问题平截面假定实际上是不成立的。此时,一维纵波传播问题转换为应力波沿三维柱体传播问题。文章从基桩三维理论出发,忽略桩土径向位移,考虑桩体中应力波沿纵向和径向传播与桩土的相互作用,建立三维条件下桩土系统瞬态振动计算模型,推导得到低应变瞬态荷载作用下基桩三维动力响应的解析解,以期为基桩低应变检测提供新的理论指导。     

钻孔变截面灌注桩施工技术研究与应用

在软土地基中提高钻孔灌注桩承载力的根本途径是施工变截面桩。在总结施工凹凸桩工法的基础上，建议在软土地基普遍推广应用变截面桩。     

粉喷桩单桩竖向抗压极限承载力预测方法

根据粉喷桩单桩静载试验所得荷载-沉降曲线对粉喷桩的极限荷载的预测方法进行了探讨,分别按照抛物线法、双曲线法和灰色理论预测方法对粉喷桩极限荷载进行了预测。结果表明:灰色理论预测值与另两种方法的预测值相比要小些,偏于安全。另外,也讨论了各种预测方法的适用性与应用条件。其方法和成果可供相同工程参考和利用。     

桩底岩溶的地质雷达探测

为探测人工挖孔嵌岩灌注桩桩底以下一定深度内发育溶洞等不良地质现象 ,采用高频地质雷达技术 ,在桩底布设环行探测剖面 ,并对雷达数据进行时间域及空间域滤波、背景干扰波去除等处理 ,可解释推断地下地质结构。经 10余个建筑场地 ,数百个桩孔的探测及开挖、钻探、静载荷试验对比验证 ,证明这是一种行之有效的探测方法     

竖向荷载下挤扩支盘桩试验成果分析

通过6根挤扩支盘桩的静载试验和桩身应力及桩端反力测试试验成果，分析挤扩支盘桩在竖向荷载下的变形受力特征，给出了对工程实践有指导意义的结论。     

钻孔灌注桩施工中几个技术问题的处理

施工中如何控制灌注桩的质量是保证桩基工程质量的重要环节。结合江苏省防汛物资储运码头工程施工实践，针对钻孔灌注桩施工中遇到的几个技术问题，提出了切合实际的处理办法，以供参考。