基桩反射波法中桩身质量的判定及分类方法

通过对反射波法特点及其局限性的分析研究 ,提出基桩完整性、砼强度及对承载力影响 ,提出对基桩质量进行评价分类的方法 ,为规范今后桩基工程检测报告中结论意见的标准化提供参考     

基于远程监控的基桩检测监督管理实践探索

基桩检测是检验基桩承载力的重要手段,依靠网络对基桩检测实施远程监控,可以规范检测单位的质量行为,确保基桩工程质量控制.文章以江苏省南通市建设工程质量监督站远程监控基桩为例,分析了基桩静载检测行为不规范的主要表现,阐述了基桩静载检测远程监控的实施程序、方法及其配套措施.     

基桩反射波法检测桩身缺陷深度的不确定度评定

作为桩基检测的常规手段,基桩反射波法检测在我国桥梁桩基检测中已有多年的历史并已纳入国家的规范.本文以某工程为例,介绍了基桩反射波法的基本原理,并阐述了基桩反射波法在桩身缺陷深度检测方面应用.     

从低应变检测结果分析扬州地区基桩常见质量问题

桩基础是土木工程中广泛采用的一种基础形式.基桩施工质量直接影响建筑物(构筑物)的正常使用.根据扬州地区大量的基桩低应变检测资料所反映出来的问题,系统分析基桩主要是预应力管桩以及钻孔灌注桩的施工质量问题,以期为工程设计、施工、检测等服务.     

低应变基桩检测中传感器及激振技术

基桩低应变检测中传感器的选择及安装技术、激振技术直接则到测试准确与否。本文根据波动理论及从事桩检测的实践经验，重点探讨低应变基桩检测中传感器技术及激振技术。     

桩基础检测技术的综合应用

针对具体工程,利用成孔质量检测、静载试验检测、低应变动力检测、钻孔取芯法检测和高应变动力检测等技术对建设工程的基桩进行了检测,进而对桩基质量做出评价,以确保建设工程的质量.     

基于Spark的大规模软件完整性

软件完整性校验广泛应用于反篡改防御,保护软件知识产权,防止盗版。因此,了解不同完整性校验方法的强度和弱点很重要。针对传统检测方法处理大规模数据时效率较低的问题,描述了一个基于Spark的大规模软件完整性校验行为识别框架。对于单个文件检测,使用后向污点分析识别可执行或者用来计算可执行位置值的内存位置,然后使用前向污点分析识别校验过程。该方法适用于多种不同完整性校验防御方案,提供的信息可以用来辅助绕过防御。实验表明,该方法可以有效识别常见软件完整性校验行为。     

基桩低应变反射波法时域信号识别技术研究

椐据检测实践和现场试验结果,对低应变反射波法检测中经常出现的典型时域信号进行了分析研究．结果表明,传感器粘贴好坏、肓区内浅部缺陷、长桩段扩颈现象,桩周土中软硬夹层的组合特性及嵌岩桩桩底岩土特性变化等,在检测曲线上均具有典型的反射信号．正确认识这些反射信号的特征,可以保证基桩低应变反射波法的检测效果．     

静载试验检测桩基承载力

由于桩基础在工程建设中起着重要的基础性作用,并且桩基础的造价通常都会比较高(在总工程造价中几乎占据了四分之一甚至更大的比重),因此对于桩基承载力的检测具有极其重要的意义.本文旨在阐述导致基桩损坏的原因、检测桩基承载能力的几种主要方法以及如何运用静载试验方法来检测桩基承载力,从而达到满足工程建设需求、实现经济技术效益最大化的目的.     

低应变反射法检测灌注桩完整性

对于带有普查性的灌注桩完整性检测,低应变反射法较为便利和经济。低应变反射法检测过程包括三大技术步骤:信号采集技术、波速确定技术和缺陷判断技术,三步骤环环相扣,均对检测效果有重要的影响。结合实践工程桩,应用低应变反射法对桩身完整性问题做出综合评价,对各代表性类型的工程桩做出判断分析。     

基于LPC预测残差的倒谱基音检测算法分析

给出了加窗语音的新倒谱模型，提出了基于语音LPC预测残差的倒谱基音周期检测算法(LP—CEP法)，该算法在倒谱计算中采取高频分量置零的新措施，仿真研究结果表明，该算法相对于传统倒谱基音检测算法(CEP法)，无论是对不同的干净语音还是对不同信噪比的含噪语音，其基音检测结果有明显的改善。     

语音信息中的基音参数检测算法分析

给出了加窗语音的新倒谱模型，提出了基于语音LPC预测残差的倒谱基音周期检测算法(LP—CEP法)，该算法在倒谱计算中采取高频分量置零的新措施。仿真研究结果表明，该算法相对于传统倒谱基音检测算法(CEP法)，无论是对不同的干净语音还是对不同信噪比的含噪语音，其基音检测结果都有明显的改善。     

频谱细化技术与功率倒频谱在振动信号分析中的应用

频谱细化技术和功率倒频谱是振动信号分析的两种重要辅助方法.采用细化处理,可以对信号频谱上感兴趣的一段频带进行“局部放大”,从而提高频率分辨率;倒频谱可以识别信号中较弱的周期成分,并对识别调制信号的边频县有特殊的效果.本文在介绍这两种方法基本原理的基础上,运用工程实例说明了其在振动信号分析中的实际应用效果.     

Studies on parallel seismic testing for integrity of cemented soil columns

The principle and process of parallel seismic (PS) testing for the integrity testing of cemented soil columns are in- troduced in this paper. A three-dimensional (3D) finite element model (FEM) for the pile-soil system is established for impulse responses. Under saturated soil or unsaturated soil condition, several vibrating velocity-time histories at different depths in parallel hole are obtained based on the numerical simulation. It shows that the length of the pile and the one-dimensional (1D) P-wave velocity in the pile can be determined easily from the features of the mentioned velocity-time histories. By examining the slopes of the first arrival time plotted versus depth or the depth where the amplitude of the first arrival significantly decreases, the length of the pile can be determined. The effects of the 3D P-wave propagation through the saturated soil and the defect of the cemented soil column on the velocity-time histories are also investigated.     

构建社会主义和谐社会的马克思主义解读

马克思主义以科学的世界观和历史观为基础，提出了完整的社会发展理论，奠定了构建社会主义和谐社会的理论基础。我们必须以马克思主义为指导，立足中国特色社会主义的伟大实践，深入把握社会主义和谐社会的科学内涵；必须坚持以科学发展观统领经济社会发展全局，从社会主义初级阶段的实际出发，牢牢把握社会主义的本质，走出一条具有中国特色的和谐社会建设道路。     

语音识别系统软件设计

提取语音信号的MFCC特征参数,用矢量量化（VQ）的LBG算法来建立匹配模板.在MATLAB软件平台上,基于GUI界面实现说话人识别系统软件设计,并通过实验验证其有效性.     

Bearing capacity and load transfer mechanism of a static drill rooted nodular pile in soft soil areas

The static drill rooted nodular pile is a new type of pile foundation consisting of precast nodular pile and the surrounding cemented soil. This composite pile has a relatively high bearing capacity and the mud pollution will be largely reduced during the construction process by using this type of pile. In order to investigate the bearing capacity and load transfer mechanism of this pile, a group of experiments were conducted to provide a comparison between this new pile and the bored pile. The axial force ofa precast nodular pile was also measured by the strain gauges installed on the pile to analyze the distribution of the axial force of the nodular pile and the skin friction supported by the surrounding soil, then 3D models were built by using the ABAQUS finite element program to investigate the load transfer mechanism of this composite pile in detail. By combining the results of field tests and the finite element method, the outcome showed that the bearing capacity of a static drill rooted nodular pile is higher than the bored pile, and that this composite pile will form a double stress dispersion system which will not only confirm the strength of the pile, but also make the skin friction to be fully mobilized. The settlement of this composite pile is mainly controlled by the precast nodular pile; meanwhile, the nodular pile and the surrounding cemented soil can be considered as deformation compatibility during the loading process. The nodes on the nodular pile play an important role during the load transfer process, the shear strength of the interface between the cemented soil and the soil of the static drill rooted pile is larger than that of the bored pile.     

砂土地基中静压桩桩端阻力分析

利用自主研制的大型土工试验装置,在考虑桩长和桩尖角度影响的情况下,开展了静压桩的沉桩以及静载荷试验,以研究试验过程中桩端阻力的变化规律。试验结果表明:沉桩过程中,桩端阻力随沉桩深度的增加而非线性增大,也随桩长和桩尖角度的增加而增大,沉桩深度为25D时,桩端阻力基本达到极值,同一沉桩深度处桩端阻力在沉桩阻力中的占比随桩长(20D~30D范围内)的增加而减小,随桩尖角度的增加而增大;静载荷试验过程中,桩端阻力随沉降量的增加而非线性增大,也随桩长和桩尖角度的增加而增大,同一沉降量处桩端阻力在桩顶荷载中的占比随桩长的增加而减小,随桩尖角度的增加而增大。     

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.