论文总字数：42618字

摘 要

水泥土搅拌桩法是目前最常用的软土地基加固方法。已有大量研究证明，在水泥土中掺入惰性物质可以有效提高水泥土的强度。本文首先对掺砂水泥土进行室内不固结不排水试验、弯曲元剪切波速测试确定了合理掺砂量，并探讨了掺砂级配对水泥土的影响效益；其次通过CT扫描成像技术对掺砂水泥土的微观形态进行观察分析，作为掺砂水泥土细观尺度建模的编写依据；在此基础上，结合已有建模思路与CT成像结果，利用Python语言编写按照一定级配随机生成多边形骨料的模型，导入ABAQUS/CAE模拟不固结不排水试验，结合室内试验对掺砂量的影响进行定性分析；在验证室内三轴试验的基础上，利用ABAQUS对掺砂水泥土模拟固结排水试验，定量分析掺砂对水泥土强度的影响；最后根据推论设置人工级配对照组，在ABAQUS中验证推论。本文的主要研究成果如下：

（1）证明了掺砂确实可以提高水泥土的强度，且随着掺砂量的增大（0%—30%），水泥土的强度呈增长趋势，并将20%的掺砂量作为合理掺砂量。

（2）通过Python语言编写了一种生成随机多边形骨料的简易方法，使得该模型在骨料占比较低、骨料尺寸接近时具有较高的生成效率。

（3）将Python脚本导入ABAQUS/CAE，利用CAE界面进行建模，定性证明了随着掺砂量的增大，砂颗粒在水泥土中的骨架作用增强。

（4）定量化阐明掺砂量的增加在水泥土中发挥的作用：在细观模拟中，随着水泥土掺砂量的增加，得到最大偏应力也相应地增大，尤其表现在水泥土内摩擦角的增大。

（5）通过建立两个相互对照的人工级配，设置颗分曲线中段的级配形式不同，最终发现两者的最大偏应力值相差较大。由此从细观模拟上证实：对掺砂水泥土强度影响最大的级配范围，可能不在粒径最大段；且存在某一段级配区间，其级配的变化对掺砂水泥土的强度具有显著的影响。

关键词：掺砂水泥土；级配；随机骨料；CT；剪切波速

Abstract

The cement-soil mixing pile method is currently the most commonly used method for reinforcing soft soil foundation. A large number of studies have proved that the incorporation of inert substances in cement soil can effectively improve the strength of cement soil. In this paper, the indoor unconsolidated undrained test and the bending element shear wave velocity test of sand-mixed cement soil are used to determine the reasonable sand content, and the effect of sand-mixed cement soil is discussed. Secondly, the CT scanning imaging technology is used to blend The microscopic morphology of sand-cement soil is observed and analyzed, which is used as the basis for the mesoscale modeling of sand-mixed cement soil. On the basis of this, combined with the existing modeling ideas and CT imaging results, the Python language is used to prepare randomly according to a certain level. The model of polygonal aggregate was introduced into ABAQUS/CAE simulation unconsolidated undrained test, combined with the indoor test to qualitatively analyze the influence of sand content; based on the verification of indoor triaxial test, the ABAQUS was used to simulate the sand-mixed cement soil. The drainage test is used to quantitatively analyze the influence of sand mixing on the strength of cement soil. Finally, the artificial gradation control group is set according to the inference, and the inference is verified in ABAQUS. The main research results of this paper are as follows:

(1) It is proved that sand mixing can improve the strength of cement soil, and with the increase of sand content (0%-30%), the strength of cement soil increases, and the sand content of 20% is the reasonable sand content.

(2) A simple method for generating random polygon aggregates is written in Python language, which makes the model have higher generation efficiency when the aggregate is relatively low and the aggregate size is close.

(3) The Python script was imported into ABAQUS/CAE, and the CAE interface was used for modeling. It was qualitatively proved that the skeletal effect of sand particles in cement soil increased with the increase of sand content.

(4) Quantitative clarification of the effect of the increase of sand content in cement soil: in the mesoscopic simulation, as the sand content of cement soil increases, the maximum deviator stress increases correspondingly, especially in cement soil. The internal friction angle increases.

(5) By establishing two artificial gradings that are mutually contrasted, the gradation form of the middle section of the fractional curve is set differently, and finally the maximum deviatoric stress values of the two are found to be large. From the mesoscopic simulation, it is confirmed that the gradation range with the greatest influence on the strength of sand-mixed cement soil may not be the largest segment of the particle size; and there is a certain gradation interval, and the gradation change has the significant impact on strength of the sand-mixed cement soil.

Keywords: Sand-mixed cement soil; gradation; random aggregate; CT; shear wave velocity

目 录

摘要 I

Abstract II

目 录 IV

图 汇 总 VII

表 汇 总 XI

第一章 绪论 1

1.1 研究背景 1

1.2 国内外研究现状 2

1.2.1 水泥固化软土地基的机理 2

1.2.2 掺砂水泥土强度性质的机理及研究 3

1.2.3 掺砂水泥土微观结构的研究 5

1.2.4 课题关键问题及难点 7

1.3 研究内容与技术路线 8

1.3.1 本文主要研究内容 8

1.3.2 技术路线 9

第二章 掺砂水泥土强度试验及分析 10

2.1 土样基本物理性质测定 10

2.2 室内试验方法概述 11

2.2.1 试验材料选取 11

2.2.2 试验主要仪器及工具 11

2.2.3 试验流程 12

2.3 确定水泥土的合理掺砂量 13

2.3.1 试验方案设计 13

2.3.2 试验结果展示 14

2.4 确定水泥土的掺砂级配 17

2.4.1 试验方案简介 17

2.4.2 试验方案设计 19

2.4.3 试验结果及分析 22

2.5 剪切波速与水泥土强度的关系 24

2.5.1 剪切波与压缩波的介绍 24

2.5.2 弯曲元试验测试剪切波速方法概述 25

2.5.3 剪切波速试验结果展示 26

2.6 本章小结 29

第三章 掺砂水泥土微观试验 30

3.1 CT扫描技术概述 30

3.1.1 CT成像的原理 30

3.1.2 CT图像的定义 30

3.2 CT图像分析 31

3.3 CT图像与数值模型设计 33

3.4 本章小结 34

第四章 基于ABAQUS的掺砂水泥土细观数值模拟 35

4.1 随机骨料的二次开发 35

4.1.1 已有模型介绍 35

4.1.2 模型编写 36

4.2 建模方案概述 38

4.2.1 部件的生成 38

4.2.2 参数设置 40

4.2.3 边界条件的确定及网格划分 40

4.3 掺砂量对水泥土强度的影响 42

4.4 掺砂级配对水泥土强度的影响 48

4.4.1 富勒法掺砂水泥土 48

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