Effect of pile-cap connection on behavior of torsionally loaded pile groups

To evaluate the responses of fixed and pinned pile groups under torsion, a method is presented to analyze the nonlinear behavior of free-standing pile groups with rigid pile caps. The method is capable of simulating the nonlinear soil response in the near field usingp-y and r-θ curves, the far-field interactions through Mindlin＇s and Randolph＇s elastic solutions, and the coupling effect of lateral resistance on torsional resistance of the individual piles using an empirical factor. Based on comparisons of the solutions for fixed- and pinned-head, 1×2, 2×2, and 3×3 pile groups subjected to torsion, it was found that pile-cap connection significantly influences the torsional capacity of pile groups and the assignment of applied torques in the pile groups. In this study, the applied torques for the pinned-head pile groups are only 44%-64% of those for the corresponding fixed-head pile groups at a twist angle of 2^o. Such a difference is mainly due to the change of the lateral resistances of individual piles in the groups.     

两层土液化场地混凝土群桩基础动力反应振动台试验研究(英文)

目的:探讨中密和密实砂液化场地混凝土低承台群桩和地基动力响应存在的差异性,并揭示引起这种差异性的原因,以期获得加密后砂土液化场地混凝土低承台群桩和地基动力反应的基本特征与规律。创新点:1.利用振动台试验,成功实施中密和密实砂液化场地低承台群桩基振动台试验;2.基于试验结果,对比中密和密实砂层液化场地群桩和地基的动力响应规律,考察两种液化场地条件下群桩效应基本特征。方法:1.通过对比白噪声扫频,获得中密砂和密实砂层液化场地下体系模态参数的差异性(图2和表1);2.通过对比砂层孔压、加速度和位移(图3–8),获得中密砂和密实砂液化场地动力反应显著的差异性;3.基于上部结构和承台的位移与加速度,讨论中密砂和密实砂液化场地上部结构动力反应与回复力特性(图9和10);4.基于桩上记录的应变时程,考虑桩的非线性,反算混凝土桩的弯矩时程,对比两类场地群桩弯矩存在的差异性,获得两类场地对群桩效应的影响效应(图12–14)。结论:1.密实砂液化场地加速度在砂层液化后未出现弱化现象,表现出明显的循环流动性,密实砂液化场地比中密砂液化场地刚度更大;2.上部结构动力响应与砂土密实状态密切相关;3.中密砂液化场地桩的最大弯矩发生在土层分界处,而密实砂液化场地中桩的最大弯矩发生在桩头处;4.群桩效应在密砂层中更显著,而在中密砂层并不显著。     

受推桩静力特性模型试验研究

本文采用模型桩进行了桩在几种水平荷载作用下桩的静力特性的试验研究,得到了桩身弯矩、桩头位移及土抗力系数等参数的一些变化规律。并进行了《m》法、《c》法及《k》法的计算比较,得出在砂土中《m》法稍优于其它两种方法。     

Study on pile drivability with one dimensional wave propagation theory

Pile drivability is a key problem during the stage of design and construction installation of pile foundations. The solution to the one dimensional wave equation was used to determine the impact force at the top of a concrete pile for a given ram mass, cushion stiffness, and pile impedance. The kinematic equation of pile toe was established and solved based on wave equation theory. The movements of the pile top and pile toe were presented, which clearly showed the dynamic displacement, including rebound and penetration of pile top and toe. A parametric study was made with a full range of practical values of ram weight, cushion stiffness, dropheight, and pile impedance. Suggestions for optimizing the parameters were also presented. Comparisons between the results obtained by the present solution and in-situ measurements indicated the reliability and validity of the method.     

桩基础对环境和建筑经济的影响

阐述了桩基础的特点和采用状况。根据环境可持续发展的要求，分析了桩基础对环境和建筑经济效益的影响，阐明了在设计环节中，慎重采用桩基础的观点。     

Study on pile drivability with one dimensional wave propagation theory

INTRODUCTIONInterestinonedimensionalwavepropagationtheoryforapplicationtounderstandingpiledriv ingismorethanacenturyold .ImportantworkdirectlyrelatedtocurrentapplicationstopiledrivabilitystartedshortlyaftertheSecondWorldWarandcontinuedtothepresent,assuchp…     

原型观测在浙医一院桩基工程中的应用

桩基础在现代建筑工程中得到了广泛的应用，但由于结构工程理念的不断更新和发展，对桩基础的设计和施工提出了更高的要求。通过确定和实施原型观测方案，获得了大量的第一手资料，并对其进行初步的整理分析，客观地揭示了工程建设进程中桩基的工作性状，反映了一些客观规律，为进一步丰富和完善桩基工程理论内涵提供了实践依据。     

IPD-80桩机液压油温异常的故障诊断与排除

本文根据IPD-80桩机液压异常的故障,从液压回路及阀的结构原理进行了多方面的分析,并进行了拆检和故障排除,对实际生产中类似的故障排除提供了相关的参考.     

《基础工程》课程教学方法的研究

本文对《基础工程》课程做了简单论述,主要对《基础工程》中一些关于基础理论、设计、计算和施工方法等教学内容在教学过程中存在的问题进行了阐释,提出构建课程体系强调思路和案例式的教学方法。     

基于现场测试的软弱黄土地基桥头引道路堤变形规律及控制措施研究

基于现场测试手段,深入研究分析软弱黄土地基桥头引道路堤变形的时空特征,并从技术方面系统提出变形控制技术措施,确保桥头引道的工程质量。通过现场观测,分析各类技术手段对桥头引道路堤变形控制的有效性。     

大直径挖孔桩在高层建筑中的应用

本文介绍了高层办公楼选择大直径挖孔扩底桩基础,具有受力明确,经济易行,质量可靠的优点,在具有较好持力层地质条件下选用此桩是适宜的.     

全容式 LNG 储罐桩基施工质量控制研究

全容式LNG低温储罐上部荷载较大,对差异沉降较敏感,基础施工要求非常严格。以天津全容式LNG储罐钻孔灌注桩施工为例,分析了影响桩基施工质量的因素,并提出了在施工过程中控制质量的措施及常见问题预防对策,以保障桩基施工质量。     

Analytical model of vertical vibrations in piles for different tip boundary conditions: parametric study and applications

In this paper,a model named fictitious soil pile was introduced to solve the boundary coupled problem at the pile tip.In the model,the soil column between pile tip and bedrock was treated as a fictitious pile,which has the same properties as the local soil.The tip of the fictitious soil pile was assumed to rest on a rigid rock and no tip movement was allowed.In combination with the plane strain theory,the analytical solutions of vertical vibration response of piles in a frequency domain and the corresponding semi-analytical solutions in a time domain were obtained using the Laplace transforms and inverse Fourier transforms.A parametric study of pile response at the pile tip and head showed that the thickness and layering of the stratum between pile tip and bedrock have a significant influence on the complex impedances.Finally,two applications of the analytical model were presented.One is to identify the defects of the pile shaft,in which the proposed model was proved to be accurate to identify the location as well as the length of pile defects.Another application of the model is to identify the sediment thickness under the pile tip.The results showed that the sediment can lead to the decrease of the pile stiffness and increase of the damping,especially when the pile is under a low frequency load.     

Analytical model of vertical vibrations in piles for different tip boundary conditions: parametric study and applicationsx

In this paper,a model named fictitious soil pile was introduced to solve the boundary coupled problem at the pile tip.In the model,the soil column between pile tip and bedrock was treated as a fictitious pile,which has the same properties as the local soil.The tip of the fictitious soil pile was assumed to rest on a rigid rock and no tip movement was allowed.In combination with the plane strain theory,the analytical solutions of vertical vibration response of piles in a frequency domain and the corresponding semi-analytical solutions in a time domain were obtained using the Laplace transforms and inverse Fourier transforms.A parametric study of pile response at the pile tip and head showed that the thickness and layering of the stratum between pile tip and bedrock have a significant influence on the complex impedances.Finally,two applications of the analytical model were presented.One is to identify the defects of the pile shaft,in which the proposed model was proved to be accurate to identify the location as well as the length of pile defects.Another application of the model is to identify the sediment thickness under the pile tip.The results showed that the sediment can lead to the decrease of the pile stiffness and increase of the damping,especially when the pile is under a low frequency load.     

挖孔灌注桩工程量的计算方法和分析

通过实例介绍了人工挖掘孔大直径扩底灌注桩工程量的计算方法。     

水泥搅拌桩（ 湿法） 施工的质量控制

用双搅头水泥搅拌桩（湿法）处理软弱地基,使其能形成复合地基,并能达到设计所要求的最终复合地基承载力特征值。满足工程要求。     

高等级公路边桩坐标计算方法探讨

文章探讨了应用南方CASS快速实现边桩坐标解算的方法,并与传统坐标计算方法得出的成果进行了比较分析,最后重点介绍了坐标纠正方法以及其在工程中的应用。     

机场航站楼桩基基础施工技术探讨

桩基基础施工技术种类繁多,常见的木桩、钢桩、钢筋混凝土桩等。在机场航站楼施工中绝大部分为钢筋混凝土桩,结合贵州省贵阳市龙洞堡国际机场1号航站楼扩建工程2标段实际情况,分别从桩基人工开挖,机械开挖等方面对机场航站楼桩基基础施工技术探讨。研究表明:机场航站楼桩基础施工技术,施工更加稳定,安全性高,施工工期更加容易掌控,值得大范围推广应用。     

既有建筑物地基基础高压注浆托换法加固的应用技术

通过工程实例，对既有建筑物地基基础因为产生不均匀沉降而进行高压注浆托换法加固的施工技术做简单介绍，阐述利用人工挖孔高压注浆桩对既有建筑物地基基础进行固结稳定和托换法的加固施工工艺。     

人工挖孔桩施工中遇到的问题及其对策

针对人工挖孔桩施工中常遇到的几个问题,提出了相应的对策.