主应力轴旋转作用下各向异性软粘土静动力特性试验研究

发布时间：2018-05-28 01:34

本文选题：软粘土 + 各向异性　；参考：《江西理工大学》2015年硕士论文

【摘要】：软粘土地基上修筑的高速公路、机场跑道、跨海大桥等交通工程在循环交通荷载作用下,往往会产生过大的工后沉降,这是因为在自重荷载和交通荷载作用下软粘土中的应力路径十分复杂,主要表现在以下两个方面,第一,软粘土具有明显的各向异性,这种各向异性一方面和K0固结有关,另一方面则由路基中的应力引起。第二,在循环交通荷载作用下,软粘土单元体中的主应力轴还会发生连续旋转。因此,开展各向异性软粘土在主应力轴旋转作用下的静动力特性试验研究是解决软土地基工程灾变问题的重要手段。本文以温州软粘土为研究对象,主要做了以下工作:1.研制出一种制备重塑土的仪器即高压固结仪,利用该仪器通过一系列的加工工艺流程制备出高质量的重塑软粘土,分别取与土样沉积方向呈0°、30°、45°、60°、90°的原状土样和重塑土样,对每种角度的原状和重塑土样依次分别进行压缩试验、渗透试验、直剪试验,结果表明:无论是重塑土样还是原状土样,其压缩模量、渗透系数、抗剪强度等方面都存在各向异性。2.利用GDS空心扭剪系统,对原状温州饱和软粘土开展与大主应力方向分别呈0°,30°,45°,60°,90°的定向剪切试验,结果表明:不同主应力方向角下的剪切,主应力、主应变、应力-应变关系曲线变化规律差别较大,偏应力峰值和内摩擦角也互不相同,且偏应力峰值在0°剪切时最大,而有效内摩擦角最大值出现在45°剪切。3.利用GDS空心扭剪系统,通过使用自定义的波形及心脏线形应力路径的加载,模拟了实际工程中交通荷载作用下土单元体中主应力轴连续旋转的应力路径,研究了主应力轴连续旋转作用下,软粘土中应变、孔压、弹性模量的变化规律,结果还发现,与不考虑主应力方向变化的动三轴试验结果相比,主应力轴旋转会加快软粘土应变、孔压的累积和土体的软化。最后建立了考虑主应力轴旋转作用的软粘土累积应变预测方程。
[Abstract]:Highway, airport runway, cross-sea bridge and other traffic projects built on soft clay foundation often produce excessive post-construction settlement under cyclic traffic load. This is because the stress paths in soft clay under gravity and traffic loads are very complex and are mainly manifested in the following two aspects: first, the soft clay has obvious anisotropy, which is related to K _ 0 consolidation on one hand. On the other hand, it is caused by the stress in the roadbed. Secondly, under cyclic traffic load, the principal stress axis in the soft clay element will rotate continuously. Therefore, the static and dynamic behavior of anisotropic soft clay under the rotation of principal stress axis is an important means to solve the problem of engineering disaster in soft soil foundation. In this paper, Wenzhou soft clay as the research object, mainly do the following work: 1. A high pressure consolidation instrument for the preparation of remolded soil was developed. High quality soft clay was prepared by a series of processing processes. The original and remolded soil samples with the direction of 0 掳~ 30 掳~ 45 掳~ 45 掳~ 60 掳~ (90 掳) and remolded soil samples were obtained, respectively, when the soil was deposited in the direction of 0 掳~ 30 掳~ 45 掳~ (45 掳) or 60 掳~ 90 掳. Compression tests, permeation tests, and direct shear tests were carried out on the original and remolded soil samples at each angle, respectively. The results showed that the compression modulus and permeability coefficient of the original soil samples, whether the remolded soil samples or the original soil samples, were tested respectively. The shear strength is anisotropic. Using GDS hollow torsional shear system, the directional shear tests of Wenzhou saturated soft clay were carried out in the direction of 0 掳/ 30 掳/ 45 掳/ 60 掳/ 90 掳respectively with large principal stress direction. The results show that the shear, principal stress and principal strain of Wenzhou saturated soft clay in different principal stress directions are different from each other. The variation law of stress-strain relation curve is quite different, the peak value of deflection stress and the angle of internal friction are also different, and the peak value of deviant stress is maximum at 0 掳shear, and the maximum value of effective internal friction angle appears at 45 掳shear. 3. By using the GDS hollow torsional shear system, by using the self-defined waveform and the loading of the linear stress path of the heart, the stress path of continuous rotation of the principal stress axis in the soil element under the traffic load in the actual engineering is simulated. The variation of strain, pore pressure and modulus of elasticity in soft clay under continuous rotation of principal stress axis is studied. It is also found that the dynamic triaxial test results are compared with those of dynamic triaxial test without considering the direction of principal stress. Rotation of principal stress axis accelerates strain, pore pressure accumulation and softening of soft clay. Finally, the cumulative strain prediction equation of soft clay considering the rotation of principal stress axis is established.
【学位授予单位】：江西理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU41

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