scholarly journals Effect of Cyclic Loading on the Lateral Behavior of Offshore Monopiles Using the Strain Wedge Model

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Keunju Kim ◽  
Boo Hyun Nam ◽  
Heejung Youn
Keyword(s):  
Cyclic Loading ◽  
Lateral Displacement ◽  
Triaxial Compression ◽  
Lateral Loads ◽  
Compression Tests ◽  
Initial Stiffness ◽  
Quartz Sands ◽  
Number Of Cycles ◽  
Lateral Behavior ◽  
Strain Wedge

This paper presents the effect of cyclic loading on the lateral behavior of monopiles in terms of load-displacement curves, deflection curves, andp-ycurves along the pile. A commercial software, Strain Wedge Model (SWM), was employed, simulating a 7.5 m in diameter and 60 m long steel monopile embedded into quartz sands. In order to account for the effect of cyclic loading, accumulated strains were calculated based on the results of drained cyclic triaxial compression tests, and the accumulated strains were combined with static strains representing input strains into the SWM. The input strains were estimated for different numbers of cycles ranging from 1 to 105and 3 different cyclic lateral loads (25%, 50%, and 75% of static capacity). The lateral displacement at pile head was found to increase with increasing number of cycles and increasing cyclic lateral loads. In order to model these deformations resulting from cyclic loading, the initial stiffness of thep-ycurves has to be significantly reduced.

scholarly journals The Effect of Vertical Loads and the Pile Shape on Pile Group Response under Lateral Two-Way Cyclic Loading

2019 ◽  
Vol 5 (11) ◽  
pp. 2377-2391
Author(s):  
Aseel Kahlan Mahmood ◽  
Jasim M Abbas
Keyword(s):  
Cyclic Loading ◽  
Cyclic Load ◽  
Lateral Displacement ◽  
Load Ratio ◽  
Pile Group ◽  
Pile Groups ◽  
Group Response ◽  
Load Intensity ◽  
Number Of Cycles ◽  
Aluminum Pipe

This paper is presented the lateral dynamic response of pile groups embedded in dry sand under influence of vertical loads and the pile shape in-group, which are subjected to the lateral two-way cyclic loads. The laboratory typical tests with pile groups (2×1) have an aluminum-pipe (i.e. circular, square) pile, embedded length to diameter of pile ratio (L/D=40) and spacing to diameter ratio (S/D) of 3, 5, 7 and 9 are used with different cyclic-load ratio (CLR) 0.4, 0.6 and 0.8. The experimental results are revealed that both the vertical and lateral pile capacity and displacement is significantly affected by the cyclic-loading factors i.e. (number of cycles, cyclic load ratio, and shape of pile) .In this study, important design references are presented. Which are explained that the response of the pile groups under cyclic lateral loading are clear affected by the attendance of vertical load and pile shape. Where, it is reduction the lateral displacement of group piles head and increase lateral capacity about (50) % compared without vertical loads. On the other side, the pile shape is a well affected to the pile response where the level of decline in lateral displacement at the pile groups head in the square pile is more than circular pile about 20 % at the same load intensity.

scholarly journals Relationship between monotonic and cyclic behavior of saturated soft clay in undrained triaxial compression tests

2021 ◽  
Author(s):  
Tingyu Wu ◽  
Jie Han ◽  
Yuanqiang Cai ◽  
Lin Guo ◽  
Jun Wang
Keyword(s):  
Cyclic Loading ◽  
Triaxial Compression ◽  
Soft Clay ◽  
Cyclic Behavior ◽  
Triaxial Tests ◽  
Engineering Practice ◽  
Compression Tests ◽  
Cyclic Tests ◽  
Saturated Soft Clay ◽  
Triaxial Compression Tests

Cyclic loading-induced deformation of soil is a common problem in the engineering practice. In the current practice, however, monotonic triaxial tests are more commonly used in the practice, due to the availability of apparatus and ease of operation. Thus, it will be very useful and practical if the monotonic triaxial tests can be used to evaluate the behavior of soil under cyclic loading. This study aims to find an explicit relationship between monotonic and cyclic behavior of saturated soft clay. Six monotonic and nine cyclic triaxial compression tests were conducted on undisturbed saturated soft clay under an undrained condition. The test results showed that the monotonic and cyclic tests shared the same stress-strain surface in a three-dimensional space p^'-q-ε_a. It is also found possible to evaluate the effective stress states of cyclic tests at two specific numbers of cycles, using corresponding monotonic tests. Based on these two findings, a simple procedure was then proposed to predict the peak axial strain for the saturated soft clay under different cyclic loadings based on the monotonic tests and only one cyclic test, which was further verified against more test data from the previous literature.

scholarly journals Shear Characteristics of Cement-Stabilized Sand Reinforced with Waste Polyester Fiber Fabric Blocks

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Xiangfeng Lv ◽  
Hongyuan Zhou
Keyword(s):  
Low Cost ◽  
Triaxial Compression ◽  
Friction Angle ◽  
Polyester Fiber ◽  
Peak Strain ◽  
Compression Tests ◽  
Initial Stiffness ◽  
Cemented Sand ◽  
Aspect Ratios ◽  
Fiber Fabric

The present paper is devoted to investigate the effects of waste polyester fiber fabric blocks on the strength and mechanical behavior of cemented sand. In the investigation, samples were prepared at four different percentages of waste polyester fiber fabric block content (0.0%, 0.5%, 1.0%, and 1.5% by weight of soil) and two different aspect ratios (2 : 1 and 3 : 1), and conventional triaxial compression tests were carried out after the curing period. The test results indicated that the addition of fibers increased peak and residual shear strengths of cemented sand and changed its brittle behavior to a more ductile one. As the fabric block content increased, the brittleness index and initial stiffness decreased, and the peak strain and internal friction angle increased. The optimal combination of the content and aspect ratio was determined to be 0.5% and 3 : 1. The integration of the fabric blocks with the cemented sand matrix was analyzed by using the scanning electron microscopy (SEM). It is found that the reinforcement effect is related to the bond strength and friction at the interface. The micromechanical properties of the fiber/matrix interface were influenced by the undulations between the fabric block components. In summary, this study presented a low-cost and environment-friendly method for reinforcing cement-stabilized sand.

Pre- and post-cyclic behavior of mixed clayey soils

2009 ◽  
Vol 46 (2) ◽  
pp. 115-128 ◽  
Author(s):  
Abbas Soroush ◽  
Hossein Soltani-Jigheh
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Triaxial Compression ◽  
Cyclic Strain ◽  
Cyclic Behavior ◽  
Clayey Soils ◽  
Compression Tests ◽  
Soil Structures ◽  
Number Of Cycles ◽  
Cyclic Strain Amplitude

Soil structures are often comprised or supported by soils that are mixtures of cohesive and granular geomaterials. These soils are termed as intermediate or mixed soils and are widely found in natural deposits and man-made soil structures. The objective of this paper is to study the behavior of mixed clayey soils under monotonic, cyclic, and post-cyclic monotonic loading, with the main focus on the last of these three. For this purpose, a number of strain-controlled monotonic, cyclic, and post-cyclic triaxial compression tests were carried out on “clay–sand” and “clay–gravel” mixtures in undrained conditions. The effects of sand (or gravel) contents, number of cycles, cyclic strain amplitude, consolidation pressure, and grain size on the mechanical behavior of the mixtures are evaluated. The major findings from the laboratory study are: (i) the addition of granular materials to the clayey soils increases excess pore-water pressure during strain-controlled monotonic undrained shearing and cyclic loading and (ii) during post-cyclic monotonic shearing, mixed clayey soils behave similarly to overconsolidated soils; the higher the granular material is, the higher the overconsolidation ratio would be. Based on the research results, an algorithm for estimating post-cyclic mechanical parameters of mixed clayey soils, without conducting cyclic and post-cyclic tests, is suggested.

scholarly journals Effect of Prior Cyclic Loading on Triaxial Compression Strength of Sliding Zone Soil of the Huangtupo Landslide

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Qiong Chen ◽  
Deshan Cui ◽  
Yu Chen ◽  
Xianyu Tao ◽  
Wei Xiang
Keyword(s):  
Cyclic Loading ◽  
Loading Condition ◽  
Stress Ratio ◽  
Axial Strain ◽  
Triaxial Compression ◽  
Cycle Period ◽  
Confining Pressures ◽  
Number Of Cycles ◽  
Logarithmic Relation ◽  
Sliding Zone

Earthquakes or cyclic loadings cause significant changes in the strength characteristics of soil. These changes, especially for sliding zone soil, can lead to catastrophic landslides. Taking into account this characteristic, this paper investigates the effects of prior cyclic loading on the consolidated undrained triaxial compression strength of sliding zone soil with the KTL triaxial automated system. Our experimental results indicate that the prior cyclic loading has a significant effect on the strength behaviour of saturated sliding zone soil. Under different confining pressures, cycle periods, and number of cycles, the samples exhibit the characteristics of strain-hardening. Deviatoric stress under cyclic loading condition is smaller than that with monotonic loading condition under different confining pressures, cycle periods, and number of cycles. As the confining pressure and cycle period increase, the failure stress ratio decreases. The axial strain exhibits a steep rise first and then stays stable under a cycle period of 90 s, while the axial strain shows a linear increase with an increase in the number of cycles under a cycle period of 10 s under confining pressures of 100 kPa and 400 kPa, respectively. The logarithmic relation correlates well with the failure stress ratio in the cyclic loading tests, which preliminary validates the applicability of logarithmic relation for sliding zone soil influenced by prior cyclic loading, providing a theoretical basis and guidance for the further understanding of strength characteristics of sliding zone soil.

scholarly journals Mechanical properties and stress–dilatancy relationships of unsaturated soil under various cyclic loading conditions

2019 ◽  
Vol 15 (7) ◽  
pp. 1799-1813
Author(s):  
Win Tun Tun ◽  
Tomotaka Sato ◽  
Hirotaka Saito ◽  
Yuji Kohgo
Keyword(s):  
Mechanical Properties ◽  
Cyclic Loading ◽  
Potential Function ◽  
Unsaturated Soils ◽  
Triaxial Compression ◽  
Saturated Soils ◽  
Loading Conditions ◽  
Compression Tests ◽  
Plastic Potential ◽  
Plastic Potential Function

AbstractMost studies investigating the effect of cyclic loading on soil properties have been conducted for saturated soils. Embankments such as fill dams, roads and railways are usually constructed by unsaturated geo-materials and retained under unsaturated conditions during their in-service periods. Then when the stabilities of the embankments against dynamic motions such as earthquakes and traffic loads are evaluated, it is necessary to account for the cyclic properties of unsaturated soils. However, there are few studies investigating mechanical properties of unsaturated soils under cyclic loadings. There are two objectives in this paper. One objective is to investigate cyclic properties of an unsaturated silt under various cyclic loading conditions, while the other is to investigate the stress–dilatancy relationships; the relation of plastic strain increment ratio,  − dεvp/dγp, versus stress ratio, q/p′; and to derive the plastic potential function of the unsaturated silt. Cyclic triaxial compression tests under various loading conditions were performed using the unsaturated silt. The material used is an artificial silty soil named DL clay. It was found from the series of the tests that the stiffness of the soil increased with an increase in suction and the number of cyclic loadings. The total volume reductions in the specimens decreased with an increase in suction. When the numbers of cyclic loadings and suction increased, the dilation also increased. Each unique stress–dilatancy relationship could be found in both loading and unloading processes. The relationships were similar to those of saturated soils under cyclic loadings. A unique plastic potential function could also be derived from the stress–dilatancy relationships.

scholarly journals Fatigue Characteristics of Limestone under Triaxial Compression with Cyclic Loading

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Yongjie Yang ◽  
Huiqiang Duan ◽  
Luyi Xing ◽  
Shan Ning ◽  
Jiakun Lv
Keyword(s):  
Cyclic Loading ◽  
Damage Evolution ◽  
Triaxial Compression ◽  
Peak Stress ◽  
Confining Pressure ◽  
Primary Phase ◽  
Fatigue Properties ◽  
Dissipated Energy ◽  
Loading Frequency ◽  
Compression Tests

This paper presents an experimental investigation of the fatigue properties of limestone subjected to triaxial compression with axial cyclic loading. Tests were conducted on intact limestone samples with a loading frequency of 0.5 Hz and a confining pressure of 10 MPa. The test results show the following five points. (1) Under triaxial conditions, the axial and circumferential deformations at the failure point induced by cyclic loading are slightly larger than the corresponding deformations at the peak stress achieved by conventional compression tests. (2) The first level cyclic loading process has a strong influence on rock deformation in the primary phase during subsequent level cyclic loading. A smaller difference in stress amplitude between the two loading stress levels leads to less deformation during the latter. (3) Circumferential and volumetric changes are more sensitive to fatigue failure in terms of deformation and strain rate than axial changes. (4) The three phases of dissipated energy evolution are consistent with a sample’s deformation such that the energy dissipation characteristics reflect the fatigue damage evolution process. (5) A new damage formula is proposed that can concisely describe a rock’s zero-cycle damage and damage evolution.

scholarly journals Investigation of Deformation Inhomogeneity and Low-Cycle Fatigue of a Polycrystalline Material

2021 ◽  
Vol 11 (6) ◽  
pp. 2673
Author(s):  
Mu-Hang Zhang ◽  
Xiao-Hong Shen ◽  
Lei He ◽  
Ke-Shi Zhang
Keyword(s):  
Cyclic Loading ◽  
Low Cycle Fatigue ◽  
Strain Tensor ◽  
Equivalent Strain ◽  
Differential Entropy ◽  
Strain Components ◽  
Deformation Inhomogeneity ◽  
Standard Deviations ◽  
Number Of Cycles ◽  
The Relationship

Considering the relationship between inhomogeneous plastic deformation and fatigue damage, deformation inhomogeneity evolution and fatigue failure of superalloy GH4169 under temperature 500 °C and macro tension compression cyclic loading are studied, by using crystal plasticity calculation associated with polycrystalline representative Voronoi volume element (RVE). Different statistical standard deviation and differential entropy of meso strain are used to measure the inhomogeneity of deformation, and the relationship between the inhomogeneity and strain cycle is explored by cyclic numerical simulation. It is found from the research that the standard deviations of each component of the strain tensor at the cyclic peak increase monotonically with the cyclic loading, and they are similar to each other. The differential entropy of each component of the strain tensor also increases with the number of cycles, and the law is similar. On this basis, the critical values determined by statistical standard deviations of the strain components and the equivalent strain, and that by differential entropy of strain components, are, respectively, used as fatigue criteria, then predict the fatigue–life curves of the material. The predictions are verified with reference to the measured results, and their deviations are proved to be in a reasonable range.

A Simple Unconsolidated Undrained Triaxial Compression Test Emulator

2015 ◽  
Vol 771 ◽  
pp. 104-107
Author(s):  
Riska Ekawita ◽  
Hasbullah Nawir ◽  
Suprijadi ◽  
Khairurrijal
Keyword(s):  
Triaxial Compression ◽  
Measurement Data ◽  
Radial Strain ◽  
Compression Tests ◽  
Viscous Effects ◽  
Axial Pressure ◽  
Strain Stress ◽  
The University ◽  
And Storage ◽  
Triaxial Compression Tests

An unconsolidated undrained (UU) test is one type of triaxial compression tests based on the nature of loading and drainage conditions. In order to imitate the UU triaxial compression tests, a UU triaxial emulator with a graphical user interface (GUI) was developed. It has 5 deformation sensors (4 radial deformations and one vertical deformation) and one axial pressure sensor. In addition, other inputs of the emulator are the cell pressure, the height of sample, and the diameter of sample, which are provided by the user. The emulator also facilitates the analysis and storage of measurement data. Deformation data fed to the emulator were obtained from real measurements [H. Nawir, Viscous effects on yielding characteristics of sand in triaxial compression, Dissertation, Civil Eng. Dept., The University of Tokyo, 2002]. Using the measurement data, the stress vs radial strain, stress vs vertical strain, and Mohr-Coulomb circle curves were obtained and displayed by the emulator.

Strength envelope of granular soil stabilized by multi-axial geogrid in large triaxial tests

2020 ◽  
Vol 57 (3) ◽  
pp. 448-452 ◽  
Author(s):  
A.S. Lees ◽  
J. Clausen
Keyword(s):  
Triaxial Compression ◽  
Triaxial Tests ◽  
Compression Tests ◽  
Failure Envelope ◽  
Element Analysis ◽  
Linear Elastic ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic ◽  
Triaxial Compression Tests ◽  
Properties Of Soil

Conventional methods of characterizing the mechanical properties of soil and geogrid separately are not suited to multi-axial stabilizing geogrid that depends critically on the interaction between soil particles and geogrid. This has been overcome by testing the soil and geogrid product together as one composite material in large specimen triaxial compression tests and fitting a nonlinear failure envelope to the peak failure states. As such, the performance of stabilizing, multi-axial geogrid can be characterized in a measurable way. The failure envelope was adopted in a linear elastic – perfectly plastic constitutive model and implemented into finite element analysis, incorporating a linear variation of enhanced strength with distance from the geogrid plane. This was shown to produce reasonably accurate simulations of triaxial compression tests of both stabilized and nonstabilized specimens at all the confining stresses tested with one set of input parameters for the failure envelope and its variation with distance from the geogrid plane.

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