低应变桩基检测

目录

摘要 (3)

Abstract (4)

第一章绪论 (5)

1.1引言 (5)

1.2桩基分类 (6)

1.3桩基工程的常见质量问题 (8)

1.4基桩动测法的发展 (11)

第二章应力波与桩的完整性 (13)

2.1基本概念 (13)

2.2桩身完整性 (14)

2.2.1桩身完整性的定义 (14)

2.2.2桩身完整性指标 (15)

2.2.3桩身缺陷指标 (15)

第三章低应变反射波法的基本原理 (17)

3.1一维波动理论 (17)

3.1.1杆的纵向波动方程 (17)

3.2 杆的纵向波动方程解答 (19)

3.2.1分离变量法求解波动方程 (19)

3.2.2采用行波理论求解波动方程 (21)

3.3应力波的相互作用在不同阻抗界面上的反射和投射 (23)

3.3.1应力波的相互作用 (23)

3.3.2应力波在杆不同阻抗界面处的反射透射 (24)

第四章测试系统 (26)

4.1激振设备 (26)

4.1.1瞬态激振设备 (26)

4.1.2稳态激振设备 (27)

4.2传感器 (29)

4.2.1压电式加速度传感器 (29)

4.2.2速度传感器 (33)

4.2.3放大器 (35)

4.2.4信号采集分析仪 (36)

第五章测试方法及数据处理 (37)

5.1测试方法 (37)

5.1.1测试参数的选择 (37)

5.1.2测试仪器和激振设备的选择 (38)

5.1.3桩头处理 (40)

5.1.4传感器安装和激振操作 (41)

5.1.5现场测试要点 (42)

5.2测试结果的计算分析 (43)

5.2.1信号后分析 (43)

5.2.2时域分析 (45)

5.2.3频域分析 (48)

5.3各类缺陷（或桩底）的波形特征 (49)

5.4工程应用 (51)

5.4.1工程及检测概述 (51)

第六章反射波法的使用总结 (56)

摘要

桩基动力检测是指在桩顶施加一个动态力（动荷载），动态力可以是瞬态冲击力或稳态激振力。桩-土系统在动态力的作用下产生动态响应，采用不同功能的传感器在桩顶量测动态响应信号（如位移、速度、加速度信号），通过对信号的时域分析、频域分析或传递函数分析，判断桩身结构完整性，推断单桩承载力。

随着我国国民经济与工程建设的快速发展，基桩检测作为隐蔽工程验收的重要环节，对保证整个工程建设的安全稳定起着十分重要的作用。在各种检测方法中，反射波法目前应用最广泛、使用最便捷，理论与实践发展也比较成熟，有比较先进的仪器设备及应用分析软件。但是总体而言，基桩检测技术在我国的应用发展时间不长，许多测试方法不仅理论上不够完善，实际应用中也存在一些问题。

在基桩完整性检测中，利用低应变法可确定桩身缺陷位置、判断缺陷的类型和缺陷的严重程度。本文主要做了一下工作：介绍低应变的基本原理、适用范围及优缺点，一维波动理论基本方程和解答，低应变桩基检测的现场注意事项，传感器的类型，时域和频域曲线的分析等。关键字：低应变；反射波法；一维波动理论；基桩完整性。

Abstract

Pile foundation dynamic testing refers to the pile top places a dynamic force (load), the dynamic force can be transient impact or steady vibration force. Pile - soil system in dynamic force produced under the action of dynamic response, the different function of sensors at the top of the pile dynamic response signal measured (such as displacement, velocity and acceleration signals) , by analyzing the signal of time domain, frequency domain analysis or transfer function analysis, determine the structural integrity of pile, the bearing capacity of single pile.

Along with our country national economy and the rapid development of engineering construction, foundation pile detection as an important part of the concealed engineering acceptance, to ensure the safety of the engineering construction stability plays a very important role. Among various kinds of detection methods, reflection wave method is the most widely used, use the most convenient, theory and practice of development is more mature, more advanced instrument equipment and application analysis software. But, overall, pile testing technology application development time is not long in our country, many test method is not only imperfect in theory, there are some problems in actual application.

In foundation pile integrity testing, use to determine the defect position of pile low strain gauge, judging defect types and severity of. This paper mainly do the job: This article introduces the basic principle of low strain, applicable range and advantages and disadvantages, and one dimension wave theory basic equations and solutions, low strain pile foundation inspection of the matters needing attention, the types of sensors ，analysis of time domain and frequency domain curves, etc Key words: Low strain; The reflected wave method; A one-dimensional wave theory; Foundation pile integrity.