接触面单元对单桩位移应力的影响分析

在用有限元法分析桩土相互作用的研究中,采用不同的接触面单元得到的结果必然不同。通过分别引入Goodman单元和Desai单元进行单桩有限元分析,研究接触面单元对桩土接触面力学特性及单桩位移应力的影响。分析认为:在桩顶荷载较小时两者的桩土接触面力学特性以及单桩的位移应力差别很小;桩顶荷载较大时,采用Goodman单元计算所得的桩顶沉降小,接触面剪应力大,轴力沿桩身递减快,桩端阻力和沉降都较小,单桩的竖向抗压极限承载力较大。     

基桩的超声波透射法检测

文中提出了一种准确判定缺陷性质、位置和大小的较合理的检测方法,并对国家规程中三种缺陷判定方法逐一进行分析,指出判断时应注意的问题。     

微型钢管桩支护结构在北京某基坑工程中的应用

介绍了北京某基坑工程,根据拟建建筑物东侧外墙距离既有建筑外墙仅1.5m的现场条件,采用微型钢管桩结合预应力锚杆的支护形式,既解决了通常用的钢筋混凝土护坡桩打桩机械所需施工面大而无法实施的困难问题,又保证了基坑的稳定以及邻近既有建筑物的安全和正常使用。重点对微型钢管桩支护结构的计算分析进行了介绍。     

振动沉管碎石挤密桩处理可液化地基

振动沉管碎石挤密桩,通过在地基中形成密实桩体和挤密作用,与原地基构成复合地基,具有良好的透水性,可加速地基固结,有效地消除液化,提高地基承载力。碎石挤密桩技术可靠,机具设备简单,施工方便节约投资,工程进度快。     

钻孔灌注桩水下混凝土灌注的施工控制

灌注水下混凝土是钻孔灌注桩成桩的关键工序,运用科学、实用的水下混凝土灌注工艺,以确保工程质量显得极为重要。     

竖向动荷载下桩尖附近应力场研究

在合理假设桩侧摩阻力在桩尖平面应力分布的基础上,推导了桩尖附近应力场公式,得出了在桩长、桩径、桩周土内摩擦角一定的情况下,桩尖地基应力与桩顶竖向动荷载的时程反应规律。并对影响桩尖地基应力的各因素进行了敏感分析,为桩尖附近其他地下结构的验算提供依据。     

桥梁桩基础施工技术探讨

桥梁桩基础是整个桥梁的重要组成部分,稳定夯实的桥梁桩基础对桥梁起到了重要的支撑作用,桥梁桩基础的质量好坏对整座桥梁的工程质量具有直接的影响.以某桥桩基施工为例,探讨钻孔桩施工技术以及需要注意的重要问题,以供同行参考.     

搅拌桩处理公路软弱地基施工工艺的探讨

以搅拌桩工艺处理软土地基,使其承压性能达到道路施工的必要条件。基于工程实践对其使用工艺进行技术优化,对于提高作业效率和降低工程成本是十分必要的。     

Corrosion rate measurements in steel sheet pile walls in a marine environment

Corrosion of steel structures in the marine environment is a major problem. The deterioration of this kind of structures is costly and difficult to predict both when designing new structures and when estimating the remaining service life time for existing structures. The aim of this investigation was to find indicative values for the corrosion rate of steel sheet piles on the Swedish west coast. Such corrosion rates (mm/year) can be used both when designing new structures by oversizing the steel thickness and when estimating the bearing capacity of existing sheet pile structures. Earlier investigations on the corrosion rates along the Swedish east coast – with salinity from about 0.2% to 0.8% – are still used today as guidelines for the corrosion rate of all steel structures in the Swedish maritime environment even though the salinity on the west coast can be as high as 3.0%.Steel sheet pile wharfs located in the port of Halmstad on the Swedish west coast were inspected by ultrasonic measurements. Three wharf structures with a total length of about 700 m were inspected. None of the inspected wharfs had or have had cathodic protection. The thickness measurements of the steel sheet pile structures were performed by divers.The age of the three inspected sheet pile structures ranged from 36 to 51 years. The dimensions of the original sheet pile sections are known. One of the quay structures is located along a river. The salinity at all wharfs varied from low values at the surface to approx. 2% at the bottom (also in the river outflow).The measured average corrosion rates were in the same order as the design values in the European code. However, the results indicate increased corrosion rates about 1 m below the mean water surface and at the level of the propellers from the ships berthing the most frequented of the inspected wharfs, 3–6 m below water surface.The tolerances of steel sheet thicknesses – usually in the order of ±6% – are often neglected when investigating the remaining thickness in steel sheet piles. A simple calculation model shows that the sheet pile must be almost 50 years of age before an accurate estimation on the corrosion rate can be made, considering the tolerances, if the true original sheet pile thickness is not known.     

高铁湿陷性黄土隧道地基处理浅析

根据湿陷性黄土隧道工程特点,结合宝兰客专客运专线王家岔湿陷性黄土隧道地基加固处理的工程实例,阐述了洞口和洞内两种施工工艺不同的水泥土挤密桩施工方案,分析了隧道内水泥土挤密桩施工对其它工序的干扰和对工期的影响,以及施工振动对初支结构和围岩稳定的危害,提出了有效的控制措施.