大直徑鉆孔灌注樁高應(yīng)變動力檢測技術(shù)研究及推廣應(yīng)用

The Research on Application of using power test techniques of high strain to test large diameter borehole dabbling pile.


 




摘  要


本文緊緊圍繞高應(yīng)變法在檢測大直徑鉆孔灌注樁承載力中的關(guān)鍵技術(shù)這一主旨，從鉆孔灌注樁的特點，動力測樁的基本原理，高應(yīng)變動力測樁的物理基礎(chǔ)、現(xiàn)場測試技術(shù)、資料的分析處理、實測效果等方面進行了分析與研究。

文中作者通過實踐找出了大直徑鉆孔灌注樁高應(yīng)變動力檢測技術(shù)的特殊性，并對其中的關(guān)鍵技術(shù)進行了研究。并把這些關(guān)鍵技術(shù)研究結(jié)果應(yīng)用于某橋梁基樁的檢測過程中，取得了令建設(shè)方滿意的結(jié)果。通過工程實踐，充分證明了一點，即大直徑鉆孔灌注樁高應(yīng)變動力檢測技術(shù)雖然比較復(fù)雜與困難，但通過對關(guān)鍵技術(shù)進行深入的分析與研究，并采取合理的處理手段，是可以用于檢測工程樁單樁承載力的。為此，高應(yīng)變檢測大直徑灌注樁可以部分的代替費時、費錢的靜載荷試驗。同時，從統(tǒng)計學角度分析，高應(yīng)變作為靜載荷試驗的補充，對整個樁基礎(chǔ)更有代表性。

文中作者把高應(yīng)變檢測結(jié)果進行分析計算，這個過程分為三個部分。第一部分通過大量的高應(yīng)變良好擬合結(jié)果，尤其是和靜載荷試驗對比過的擬合結(jié)果，得到某個地質(zhì)條件下的樁土作用參數(shù)，對這些參數(shù)進行收集和整理，可以用于指導以后類似工程的擬合分析。第二部分根據(jù)高應(yīng)變的檢測結(jié)果，統(tǒng)計計算出不同地層單元的樁周土極限摩阻力和樁尖土極限承載力，可以作為本地經(jīng)驗值，應(yīng)用于同種施工工藝的樁型的設(shè)計工作中。第三部分是統(tǒng)計與分析某地區(qū)大直徑鉆孔灌注長樁（樁徑≥1200mm，樁長/樁徑>30）在設(shè)計荷載作用下的承載性狀，得出樁側(cè)阻力占到樁總阻力的80%以上，樁側(cè)阻力起主要承載作用。


關(guān)鍵詞：高應(yīng)變，大直徑鉆孔灌注樁，實測曲線擬合法


 




Abstract

On the characteristics of borehole dabbling pile, fundamentals of power test the pile, and physical basis, on-the-spot test, material processing and actual effectiveness of high strain power test the pile, this paper made an analysis and research, encircling the gist that the core techniques of using high strain to test the bearing strength of large diameter borehole dabbling pile.

In this paper, the author found the particularity of using high strain to power test the large diameter borehole dabbling pile on the base of practice, and made a research of its core techniques. The results obtained had been applied to the testing course of piles of bridges in the expressway of     with satisfactory results. The engineering practice proved that it is complex and difficult to use the power test techniques of high strain to test large diameter borehole dabbling pile. However, it can be used to test the bearing strength of one engineering pile by analyzing its core techniques and taking rational methods. Therefore, we can use high strain to test the bearing strength of large diameter borehole dabbling pile to partly instead of dead load experiment with saving both time and money. At the same time, high strain is represential for the pile as the supplement of dead load experiment.

The author analyzed the results of high strain test by three steps. First, the author collected and collated the acting parameters of pile-soil in certain geological condition to guide the fitting analysis to come. These parameters come from a large number of good results of high strain, especially results compared with dead load experiment. In the second part, the limit frictional resistance of the earth around pile and the limit bearing strength of the earth of tip pile in different stratum units were counted and calculated, using in the designing of piles in the similar execution as local empirical data. In the third part,  the author counted and analyzed  the bearing strength behavior of large diameter borehole dabbling long pile (d≥1200mm, l/d>30) under designed-load conditions, and got results that resistance of pile side occupied over 80%of the whole with main effect of bearing strength.

 

Key words:  high strain，large diameter borehole dabbling pile，

            actual curve fitting


目    錄

1 緒論 1

1.1鉆孔灌注樁的概述 1

1.1.1 鉆孔灌注樁的發(fā)展 1

1.1.2 鉆孔灌注樁的特點 1

1.2 高應(yīng)變動力檢測概述 3

1.2.1 高應(yīng)變動力檢測技術(shù)的發(fā)展 3

1.2.2 高應(yīng)變動力檢測分析方法簡介 4

1.3研究大直徑鉆孔灌注樁高應(yīng)變動力檢測技術(shù)的意義 4

1.4 本文的研究思路和技術(shù)路線 5

2 樁的動力檢測技術(shù)的基本理論 7

2.1 一維波動方程 7

2.2應(yīng)力波在不同阻抗界面上的反射和透射 8

3  高應(yīng)變法測試與分析 11

3.1載力計算方法—實測曲線擬合法 11

3.1.1 樁土體系的基本假定 11

3.1.2應(yīng)力波的基本描述及其作用規(guī)律 11

3.1.3 彈性波速 14

3.1.4樁身阻抗變化對應(yīng)力波傳播的影響 15

3.1.5土阻力所產(chǎn)生的應(yīng)力波及其傳播規(guī)律 17

3.1.6樁身阻抗變化和土阻力在F—V圖上的表現(xiàn) 18

3.2承載力計算方法—凱司法 20

3.2.1凱司法的近似假..