【作者】 蔡靖；

【导师】 王建华； 张献民；

【作者基本信息】 天津大学 ， 岩土工程， 2004， 博士

【摘要】 在基桩完整性检测中,基桩缺陷程度的定量化是一个迄今为止尚未完全解决的关键问题。作为隐蔽结构,水泥搅拌土防渗墙的质量控制是整个建设过程中很重要的一方面,但其往往也是最困难的。针对以上两种情况,本文作了以下几方面的工作。通过求解均质土和成层土中完整桩、缺陷桩在瞬态力作用下的定解问题,得到均质土中完整桩和成层土中缺陷桩任意质点的瞬态响应解析解。在此基础上通过理论分析,得到桩身应力波衰减规律,为桩侧土阻尼系数的试验研究奠定了理论基础。基于应力波反射理论和桩身应力波衰减规律,给出了利用缺陷反射波与入射波幅值比确定缺陷程度的量化分析方法。通过桩土相互作用的室内和现场试验,研究了桩侧土阻尼系数的分布规律。针对两种含水量的砂土、粉土、粉质粘土,应用应力波反射法进行了小应变下桩土相互作用的室内和现场试验,得到了桩侧土阻尼系数随桩周土应力的分布关系式。将桩侧土阻尼系数分布关系式与缺陷程度量化分析方法相结合,形成了能够考虑桩周土实际阻尼分布的缺陷程度量化分析模型。为解决利用传统信号处理方法无法确定裂缝、断桩及浅部缺陷的位置问题,通过引入小波变换多分辨率分析方法,应用Db5小波对具有以上缺陷的桩的实测信号进行分析。结果表明,此方法能够清晰识别缺陷的位置。针对水泥搅拌土防渗墙这种隐蔽工程,通过现场模型墙试验和大量室内实验,建立了评价水泥土防渗墙墙体均匀性、局部质量缺陷及墙体强度的定量综合评价标准。进一步通过现场试验,研究了适用于水泥搅拌土防渗墙的瞬态面波无损检测技术并建议了相关的试验检测参数。更多还原

【Abstract】 In the pile integrity detection, quantitative analysis of defects is a problem unsolved so far. As a hidden structure, it is important and difficult how to control construction quality of soil-cement seepage prevention wall. To solve the two problems, following researches have been done. Instantaneous response analytic solutions of the integrated pile in homogenous soil and the defective pile in layered soils are obtained along the pile by solving the mathematic problem. The degradation of stress wave along piles is analyzed on the solution, which supplys to the theory basis for the following laboratory experiments. The quantitative analysis method of defects is developed on reflecting wave theory and the degradation relation of stress wave, in which a ratio of the reflecting and incident wave amplitude is used to evaluate the degree of a defect. Laboratory and in-situ tests of pile-soil interaction at low-strain have been conducted in the sand, the silt and the silty clay of two different water contents to determine the damping coefficient. The correlation between the damping coefficient and effcitve overburden press of strata around pile is established. The correlation is combined with above analysis method to establish the model quantitatively analyzing the defects of piles. Because the traditional Fourier processing method can’t detect the locations of the fracture, the break and shallow defects in pile, the multi-resolution analysis of wavelet transform is introduced to detect them. Here, the Db5 wavelet is used to analyzing signals of these defective piles. The results show that the method can identify those defects clearly. Finally, the quantitative synthetical evaluation standard is established by in-situ and laboratory tests on soil-cement seepage prevention wall to evaluate construction quality of walls. Then, the nondestructive technique detecting construction quality of the soil-cement seepage prevention wall is further studied on the instantaneous surface-wave principle by in-situ test. Key detection parameters are suggested for nondestructive detection of the wall.更多还原