宝钢厚板厂新建2#和3#热处理线工程基础施工难点及对策

针对宝钢厚板厂新建2#和3#热处理线工程工期短、施工场地狭长、周边生产设施多、新建设备基础埋深较深,并与周边生产设施紧邻等特点,结合宝钢地区的地质条件,系统阐述如何运用砂桩、钻孔沉桩、旋喷桩内插H型钢、坑内坑底旋喷注浆加固、搅拌桩重力挡土墙支护等施工技术,最大限度地消除桩基沉桩施工和设备基础深基坑施工过程中对周边建(构)物的影响.同时,运用监测手段对周边建(构)物的位移及沉降进行监控,并根据监测结果动态地调整施工节奏和及时采取预防措施.     

高压旋喷与静压注浆相结合补强加固桩基础

通过某工程实例 ,针对桩基础常见桩身混凝土质量差、承载力不能满足设计要求的问题 ,运用高压旋喷与静压注浆技术解决桩身补强加固的方法 ,达到预期的目的 ,符合使用要求 ,取得较好效果 ,为同类型桩基础处理提供一种可靠的施工方法 .     

旋喷桩在基础加固中的应用

本文通过工程实例介绍了旋喷桩在基础加固中的方案选用及施工工艺过程，及施工中应注意的事项。     

后压浆技术在CFG桩地基处理工程中的应用

朔黄发展大厦工程采用CFG桩复合地基,并进行桩基的后压浆处理,不仅提高了复合地基的承载力,而且缩短了桩长,加快了施工进度.经试验及时间检验,该工程地基处理效果良好,技术经济效益显著.结合该工程实例,介绍了CFG桩后压浆施工技术.     

刚-柔性桩复合地基在改建工程中的应用

介绍了某改建工程的基础设计中采用的复合地基处理的案例,提出了结合原有沉管灌注桩基,采用高压旋喷注浆法进行补充,形成刚一柔性桩复合地基的地基处理方法,取得了良好的处理效果,为类似地基加固处理工程提供参考。     

高压旋喷水泥土桩在工程施工中的应用

通过在几个工程的实际应用，提出高压旋喷水泥桩施工中的注意事项并提出了有关设计的参考参数。     

桩基施工技术在矿山工程中的应用

矿山工程中一般使用桩基施工技术对地下部分进行加固,因此对桩基施工技术在矿山工程中的应用方法进行分析说明。首先进行施工现场准备,平整场地并了解施工现场情况,从而制定出可行计划,施工过程中合理编制桩基施工方案,理论与实际相结合,对管波探测现场装置进行设计,引入钻(冲)孔灌注桩技术,经过测量定位、钻机移机就位、测量精放样、埋设护筒、制备泥浆,完成桩基施工。在施工中对各阶段质量控制要点进行分析,完成桩基施工技术在矿山工程中的应用研究。     

珠海“新世界”工程桩基的设计和研究

通过对“新世界”工程桩基方案的设计和研究，对珠海地区花岗岩残积土地基的特点、承载潜力的开发利用和高层建筑桩基持力层的选择、桩型方案的确定、打桩施工控制等问题，从设计理论和工程实践等方面进行分析和总结，供同类工程参考和进一步研究探讨。     

某工程桩基方案比选

以某海外工程为例，介绍了该项目地质分层情况，以及土壤电阻率和硫酸盐含量情况，判断该工程场地具备一定的腐蚀性。基于地勘资料，综合考虑了预应力管桩、混凝土钻孔桩及旋挖植桩法等桩型方案，并进行了相关计算，对桩基方案进行了综合比选，提出了最优桩基方案。     

振动沉管砼灌注桩的质量通病及防治

振动沉管砼灌注桩是建造多、高层建筑的一种理想的基础形式。但在实际工程中，因设备尺寸掌握不准，施工过程、质量控制不严，桩体缩径、断桩事故时有发生。本对沉管灌注桩在设计、施工中的常见通病及预防措施进行论述、探讨。     

能源桩三维螺旋线热源的瞬态传热模型

将螺旋埋管等效为三维螺旋线热源,考虑螺旋埋管能源桩的传热过程,运用格林函数和第一型曲线进行积分,推导给出了考虑时间、空间位置、埋管参数和岩土体热物理性质4参数的螺旋埋管能源桩的温度场解析解,建立高精度三维螺旋埋管能源桩的传热模型。并通过在数值模拟软件中建立螺旋埋管能源桩三维模型,依据边界条件,求解得出三维螺旋埋管能源桩温度场数值解。对比结果表明:所建立的能源桩三维螺旋线热源模型具有很高的解析精度。最后,基于解析模型讨论了螺旋埋管能源桩换热温度场的空间分布和时间效应。      

无砂混凝土小桩地基处理技术介绍

作为一种新型的地基加固方法,详细介绍了无砂混凝土小桩地基处理技术的原理、设计及施工工艺,与其他类似地基处理工艺比较,可减少用桩量,大大缩短工期,节省投资。     

浙东沿海地区沉桩引起的孔隙水压力的计算

沿海软土地区中桩基设计与沉桩引起的孔隙水压力大小及其消散有密切关系，通过对挤土桩沉桩过程的理论研究和资料分析，并对实测资料进行了对比和概括，探讨了沉桩时单桩与群桩周围土中产生的孔隙水压力的大小、分布及影响范围，对具体工程桩的施工和设计均有参考意义。     

水泥土群桩复合地基桩土应力比测试研究

桩土应力比是反映搅拌桩复合地基工作状态的一个重要参数,也是计算复合地基承载力和沉降的重要指标。通过在单桩、四桩承台下的桩周土和桩顶埋设土压力盒．获得系统的水泥土桩复合地基的桩土应力等原位试验数据。分析了群桩效应在搅拌桩复合地基中的影响,具有工程实用价值。     

长螺旋水下灌注成桩技术在实践中的应用

深基坑支护是工程建筑界要经常面临的一项技术难题,文章介绍了长螺旋钻孔压灌超流态混凝土桩技术在深基坑支护中的应用.该技术是在普通螺旋干钻孔桩基础上发展创新的,用改装后的长螺旋钻机钻至设计深度,在提钻的同时,通过压力冲破钻杆内腔钻头活门上的橡皮封头向孔底连续压灌制备好的超流态混凝土至桩顶为止.然后震入底部800 mm为锥型的钢筋笼而成桩体.     

Optimization of Pile Groups Using Hybrid Genetic Algorithms

This paper presents an automated optimal design method using a hybrid genetic algorithm for pile group foundation design. The design process is a sizing and topology optimization for pile foundations. The objective is to minimize the material volume of the foundation taking the configuration, number, and cross-sectional dimensions of the piles as well as the thickness of the pile cap as design variables. A local search operator by the fully stressed design (FSD) approach is incorporated into a genetic algorithm (GA) to tackle two major shortcomings of a GA, namely, large computation effort in searching the optimum design and poor local search capability. The effectiveness and capability of the proposed algorithm are first illustrated by a five by five pile group subjected to different loading conditions. The proposed optimization algorithm is then applied to a large-scale foundation project to demonstrate the practicality of the algorithm. The proposed hybrid genetic algorithm successfully minimizes the volume of material consumption and the result matches the engineering expectation. The FSD operator has great improvement on both design quality and convergence rate. Challenges encountered in the application of optimization techniques to design of pile groups consisting of hundreds of piles are discussed.     

粉喷桩加土工格栅复合地基处理施工技术浅析

本文介绍了粉喷桩加土工格栅复合地基加固机理 ,提出了粉喷桩加土工格栅的施工方法及施工中常见问题的解决办法。     

1880热轧带钢工程加热炉区深基坑围护及土体位移有限元分析

软土地基深基坑开挖过程中,由于降水质量、基坑围护不同,或者土方开挖工况选择不当,常会引起土体位移,对管桩产生较大的土压力,出现基坑滑坡、桩身偏斜等质量事故,特别是大面积群桩整体位移,对工程本身将造成较大的经济损失和工期延误.采用桩土共同建模,桩土单元之间位移协调的有限元方法,将桩土单元集成总体刚度矩阵整体分析,对宝钢1880热轧带钢工程加热炉深基坑开挖过程进行研究,对比计算了基坑开挖对土体侧移和土体应力分布的影响,对施工工况的设计具有参考作用.     

Reduced Modulus Action in U-Section Steel Sheet Pile Retaining Walls

U-section steel sheet piles are used for constructing retaining walls and they are connected together to form continuous walls using sliding joints located along their centerlines. Interpile movement along these joints can, in theory, reduce strength by 55% and stiffness by 70%, in comparison with the performance of piles in which no slip occurs (full composite action). This problem of interlock slippage is known as reduced modulus action (RMA). Despite the potential for this problem, it is common practice in many countries to ignore RMA in design, although the exact conditions governing when it becomes a design issue are not fully understood. This paper presents results from an investigation into this problem using experimental tests carried out using miniature piles. Unlike previous studies these tests were carried out using a similar load arrangement to that found in practice. The investigation indicates that the loading configuration affects the development of RMA and that friction between pile interlocks has the potential to mitigate much of the effect of RMA. A numerical model simulating the tests was developed and it has been used to model full-scale piles. The study indicates that many commonly occurring forms of steel sheet pile walls are unlikely to exhibit significant problems from RMA and this is relevant to pile design using Eurocode 3: Part 5.     

A Robust Macroelement Model for Soil–Pile Interaction under Cyclic Loads

The principal focus of this study is the development of a robust macroelement model for soil–pile interaction under cyclic loads. The model incorporates frictional forces and formation of gaps at the soil–pile interface as well as hysteretic behavior of the soil. The plastic envelope of the soil behavior is modeled via the so-called p–y approach, outlined in American Petroleum Institute’s guidelines for design of foundation piles for offshore platforms. The macroelement is an intuitive assembly of various basic elements, each of which incorporating a particular aspect of the soil–pile interaction. The modular structure of this macroelement allows straightforward adaptation of improved constitutive models for its building blocks. Herein, we focus on large-diameter, cast-in-drilled-hole reinforced concrete piles (piers) that are partially or fully embedded in soil. These types of piles are frequently used as support structures in highway construction. Consequently, the numerical robustness of the interaction model is assessed with parametric studies on pile systems and soil types relevant to this type of construction. Both elastic and inelastic pile behaviors are considered in the parametric studies. The results indicate that the proposed interaction element is numerically robust, and thus, amenable to routine structural analysis.