雅康高速公路泸定大渡河桥重力锚边坡粗粒土蠕变特性及其应用研究

发布时间：2018-02-04 13:24

  本文关键词： 重力锚边坡 粗粒土 直剪蠕变试验 颗粒级配 长期稳定性　出处：《西南交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：在山区道路工程建设中常常会遇到粗粒土边坡,粗粒土的工程性质直接决定着工程边坡的稳定性,其蠕变变形特性对边坡的长期稳定性有重要影响。本文依托四川雅安至康定高速公路沪定大渡河桥位由粗粒土构成的重力锚边坡工程,通过普通直剪试验和直剪蠕变试验研究了粗粒土的力学性质,分析了颗粒级配和含水量的变化对其蠕变特性的影响,进而通过Flac3D数值模拟分析了成桥后重力锚边坡的长期稳定性。主要研究工作及结果如下:(1)针对桥位重力锚边坡的粗粒土进行现场取样,在原土样的基础上配制了 3种不同颗粒级配的粗粒土试样,采用普通直剪试验和改制的直剪蠕变试验测试了不同含水量情况下的不同试验土样的力学特性,得到该试样的长期抗剪强度约为快剪强度的0.7～0.8倍,试样摩擦角降低2°左右。(2)随着粒径大于5mm的颗粒含量P5的增加,试样长期粘聚力c∞值逐渐降低,长期内摩擦角Φ∞值逐渐增加,同普通直剪试验得到的抗剪强度指标变化规律相似。土样含水量由10%降至5%,Φ∞约增加2°,c∞值则提高约30%。(3)利用Matlab程序对试验测得的土样蠕变曲线进行拟合,符合Burgers模型基本特征。通过对试样的Maxwell及Kelvin单元剪切模量及粘滞系数计算分析,得到了在不同竖向压力和剪切应力作用下试样的P5对初始剪切模量G1、长期剪切模量G2、黏滞系数η1和黏滞系数η2的影响规律。随着P5增加,G1基本不变,但G2、η1和η2随之逐渐减小。(4)基于试验确定的土体蠕变特性,采用Flac3D三维数值模拟方法分析了重力锚边坡的长期稳定性。结果表明,大渡河桥重力锚边坡在5年内的稳定性良好,锚碇朝大渡河方向位移增加值为13.59cm,处于有效工作状态。对比3种级配的土体试样,得到在土体颗粒级配P5=20.7%时,锚碇朝大渡河方向位移增加值最小。本文研究确定的桥位重力锚边坡粗粒土蠕变特性,及相关的边坡长期稳定性分析结果,可为工程实际提供重要参考。
[Abstract]:The coarse grained soil slope is often encountered in the mountain road engineering construction. The engineering properties of the coarse grained soil directly determine the stability of the engineering slope. The creep deformation characteristics have an important effect on the long-term stability of the slope. This paper relies on the gravity anchor slope engineering of the Dadu River bridge of the Ya'an to Kangding expressway in Sichuan province. The mechanical properties of coarse grained soil were studied by normal direct shear test and direct shear creep test, and the effects of particle gradation and water content on the creep properties were analyzed. Then the long-term stability of gravity anchor slope after completion of the bridge is analyzed by Flac3D numerical simulation. The main research work and results are as follows: 1) sampling the coarse soil of gravity anchor slope at bridge site. Three kinds of coarse grained soil samples with different gradation were prepared on the basis of original soil samples. The mechanical properties of different test soil samples with different water content were tested by normal direct shear test and modified direct shear creep test. The long-term shear strength of the sample is about 0.7 ~ 0.8 times of that of the fast shear strength, and the friction angle of the sample is reduced by about 2 掳. 2) with the increase of the particle content P _ 5 when the diameter is larger than 5 mm. The long-term cohesion C 鈭，

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