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1.
This paper presents a semi-analytical method to solve one dimensional consolidation problem by taking consideration of varied compressibility of soil under cyclic loading. In the method, soil stratum is divided equally into n layers while load and consolidation time are also divided into small parts and time intervals accordingly. The problem of one-dimensional consolidation of soil stratum under cyclic loading can then be dealt with at each time interval as one-dimensional linear consolidation of multi-layered soils under constant loading. The compression or rebounding of each soil layer can be judged by the effective stress of the layer. When the effective stress is larger than that in the last time interval, the soil layer is compressed, and when it is smaller, the soil layer rebounds. Thus, appropriate compressibility can be chosen and the consolidation of the layered system can be analyzed by the available analytical linear consolidation theory. Based on the semi-analytical method, a computer progra 相似文献
2.
The variation of effective stress ratio of stratfied soil with semi-pervious boundaries and under cyclic loading was analyzed on the basis of Terzaghi's one-dimensional consolidation assumptions. A solution by Laplace Transform was obtained for the case when the soil was under time-varied loading. With numerical inversion of Laplace Transform, some useful results were obtained for several kinds of commonly encountered loadings. The results can be meaningful in engineering practice. 相似文献
3.
The variation of effective stress ratio of stratfied soil with semi-pervious boundaries and under cyclic loading was analyzed
on the basis of Terzagh's one-dimensional consolidation assumptions. A solution by Laplace Transform was obtained for the
case when the soil was under time-varied loading. With numerical inversion of Laplace Transform, some useful results were
obtained for several kinds of commonly encountered loadings. The results can be meaningful in engineering practice.
Project supported by the National Natural Science Foundation of China (No. 59908012) and Fok Ying Tung Education Fundation
(No. 81067), Education Ministry of China. 相似文献
4.
The authors give the solution to the problem of one-dimensional consolidation of double-layered ground with the use of the
differential quadrature method. Case studies showed that the computational results for pore-water pressure in soil layer agreed
with those of analytical solution; and that in the computational results for the interface of soil layer also agreed with
those of the analytical solution except for the small discrepancies during shortly after the start of computation. The advantages
of the solution presented in this paper are that compared with the analytical solution, it avoids the cumbersome work in solving
the transcendental equation for eigenvalues, and in the case of the Laplace transform solution, it can resolve the precision
problem in the numerical solution of long time inverse Laplace transform. Because of the matrix form of the solution in this
paper, it is convenient for formulating computational program for engineering practice. The formulas for calculating double-layered
ground consolidation may be easily extended to the case of multi-layered soils.
Project (No. RC9609) supported by the Zhejiang Provincial Natural Science Foundation of China 相似文献
5.
There exists a critical cyclic stress ratio when sand or clay is subjected to cyclic loading. It is an index distinguishing stable state or failure state. The soil static and dynamic universal triaxial and torsional shear apparatus developed by Dalian University of Technology in China was employed to perform different types of tests on saturated soft marine clay in the Yangtze estuary. Undisturbed samples were subjected to undrained cyclic vertical and torsional coupling shear and cyclic torsional shear after three-directional anisotropic consolidation with different initial consolidation parameters. The effects of initial orientation angle of major principal stress, initial ratio of deviatoric stress, initial coefficient of intermediate principal stress and stress mode of cyclic shear on the critical cyclic stress ratio were investigated. It is found that the critical cyclic stress ratio decreases significantly with increasing initial orientation angle of major principal stress and initial ratio of deviatoric stress. Compared with the effects of the initial orientation angle of major principal stress and initial ratio of deviatoric stress, the effect of initial coefficient of intermediate principal stress is less evident. Under the same consolidation condition, the critical cyclic stress ratio from the cyclic coupling shear test is lower than that from the cyclic torsional shear test, indicating that the stress mode of cyclic shear has an obvious effect on the critical cyclic stress ratio. The main reason is that the continuous rotation in principal stress directions during cyclic coupling shear damages the original structure of soil more than the cyclic torsional shear does. 相似文献
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7.
Based on consolidation equations proposed for unsaturated soil, an analytical solution for 1D consolidation of an unsaturated single-layer soil with nonhomogeneous mixed boundary condition is developed. The mixed boundary condition can be used for special applications, such as tests occur in laboratory. The analytical solution is obtained by assuming all material parameters remain constant during consolidation. In the derivation of the analytical solution, the nonhomogeneous boundary condition is first transformed into a homogeneous boundary condition. Then, the eigenfunction and eigenvalue are derived according to the consolidation equations and the new boundary condition. Finally, using the method of undetermined coefficients and the orthogonal relation of the eigenfunction, the analytical solution for the new boundary condition is obtained. The present method is applicable to various types of boundary conditions. Several numerical examples are provided to investigate the consolidation behavior of an unsaturated single-layer soil with mixed boundary condition. 相似文献
8.
Stable response of axisymmetric two-phase water-saturated soil 总被引：1，自引：0，他引：1
Biot's dynamic consolidation equations and Hankel transform were used to derive the integral solutions of stress and displacement for axisymmetric harmonic excitations in the two-phase saturated soil with subjacent rock-stratum. The influence of the coefficient of permeability and loading frequency on the soil displacement at the ground surface were studied. The results showed that higher loading frequency led to more dynamic characteristics; and that the effect of the soil permeability was more obvious at higher frequencies. 相似文献
9.
罗曦芸 《实验室研究与探索》2000,19(4):50-52
分别测定了用加填充物法脱水加固饱水古木时加固液渗透量受木材含水率的影响以及浸渍温度、添加溶剂对处理周期的影响。结果表明：高含水率古木由于内部木纤维素几乎全部降解,在相同浓度加固液中,加固剂的尖一增加,在实际自理中采用高浓度加固液更有利于器物定型,温度升高和添加溶剂,有利于降你加固液的黏度和表面张力,提高渗透速度,缩短处理时间。 相似文献
10.
Biot's dynamic consolidation equations and Hankel transform were used to derive the integral solutions of stress and displacement for axisymmetric harmonic excitations in the two-phase saturated soil with subjacent rock-stratum. The influence of the coefficient of permeability and loading frequency on the soil displacement at the ground surface were studied. The results showed that higher loading frequency led to more dynamic characteristics; and that the effect of the soil permeability was more obvious at higher frequencies. 相似文献
11.
强夯法处理湿陷性黄土地基具有施工简便、快速有效、造价经济、质量可靠的优点.它对增强地基密实度、消除土层湿陷性、降低土层压缩性和提高地基承载力效果显著.针对某仓库地基强夯工程,对强夯加固效果进行分析,采用文中建议的公式计算夯后地基承载力,理论计算值与实测值基本吻合. 相似文献
12.
在考虑软土超载预压后的次固结变形特性的基础上,推导出消除使用荷载作用下的主固结所需预压时间的公式.通过室内试验研究了不同超载量和不同超载预压时间对饱和软土次固结变形的影响,对排水固结法处理软土地基有一定的参考价值. 相似文献
13.
土的固结过程与渗透性质关系密切,但传统的固结仪不能进行渗透试验。该文研制了一种渗透固结装置,既能进行固结试验和渗透试验,又能测量固结过程中的孔压。装置构造简单,操作便捷,密封性能好,可自动记录孔压、时间等参数。该装置应用于研究生的土工试验教学,促进了土力学理论与实践教学的融合,不仅加深了学生对理论知识的理解,提高了学生分析和解决问题的能力,还增强了学生的科研思维和动手实践能力,从而提高了人才培养质量。 相似文献
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INTRODUCTION An important problem in foundation engineeringis the determination of the rate of settlement of a raftfoundation placed on a deep clay layer. Gibson andMcNamee (1957), and McNamee and Gibson (1960a;1960b) considered the problem of normal uniformloading applied to the surface of a half-space andshowed that one-dimensional theory gives a markedunderestimate of the rate of settlement. This theorycorresponds to the case of a perfectly flexible footing.However, it is often… 相似文献
15.
土地整理的生态环境影响及对策 总被引：1，自引：0，他引：1
尹力军 《唐山师范学院学报》2010,32(3):99-101
土地整理过程对区域水环境系统、植被系统、土壤环境、大气环境及敏感生态系统都会产生一定的不利影响。现阶段,土地总体利用规划不够完善、土地整理投入不足、相关基础研究不能满足需要、相关法律、法规不健全则是导致不利环境影响的主要原因。针对这种现状,提出以生态学基本理论为基础开展土地整理工作、加强国民生可持续发展意识和生态保护意识教育、增加投入、加强土地生态系统研究等建议。 相似文献
16.
连云港海相软土具有含水量高、压缩性高、孔隙比高、强度低等特点,其工程性质较差,是该地区基础设计的重点和难点。结合某海相软土的加固处理工程,阐述了动力排水固结的加固机理,并对其加固效果进行了分析。检测结果显示,动力排水固结法处理连云港软粘土场地可以取得良好效果,其经验可供类似工程参考。 相似文献
17.
用标准的数学物理方法详细推导一维渗流固结微分方程的傅里叶级数解,并用Mathematica绘制了压力分布的三维图,直观地展示了渗流固结过程中压力随深度和时间变化的物理规律.讨论了固结度实用公式的理论依据.结果表明:不同的边界条件决定了不同的物理进程;当t=0时,固结微分方程的级数解不适用于排水面;固结度两个实用公式的最佳转换点是Ut=0.5,而不是Ut=0.6. 相似文献
18.
Cover-bearing-type bucket foundation for offshore wind turbines has been paid more and more attention due to its low cost and great bearing capacity. In order to ensure the cover-bearing mode, the muddy soil inside the bucket foundation should be reinforced by some soil consolidation methods, such as negative pressure and electro-osmosis. Firstly, tests were conducted to obtain the reasonable current density. Meanwhile, to improve the electro-osmotic speed and effectiveness, other factors such as intermittent power and layout of electrode, were also studied in the tests. Then, the soil reinforcing tests by negative pressure combined with electro-osmosis were performed for the muddy soil consolidation inside the bucket foundation. The results showed that soil reinforcement by negative pressure was quicker and more obvious during the early phase, and electro-osmotic method can affect more range of soil by rational arrangement of electrodes. Compared with negative pressure, the electro-osmotic method was a continuous and relatively slow process of reinforcement, which was complementary to the negative pressure method. The voltage value of electro-osmosis had little effect on the muddy soil reinforcement inside the bucket foundation, and 1.5 A was chosen as the most reasonable current value for scale model testing in the electro-osmotic method. 相似文献
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INTRODUCTION Since the development of the conventionalconsolidation theory by Terzaghi (1943) in 1923,many attempts have been made to present some solu-tions for the problems considering more realistic as-sumptions on the practical geotechnical engineering.Some efforts have been made to avoid limitation ofthe assumptions in the Terzaghi’s theory. During theconsolidation of soil, it is obvious that the coefficientof volume compressibility mv and the coefficient ofpermeability kv ar… 相似文献