scholarly journals Laboratory Investigation on the Stress-Dependent Anisotropic Shear Wave Velocity (Vs) and Coefficient of Lateral Earth Pressure at Rest (K0) of Granular Materials

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Guangbo Du ◽  
Nina Liu ◽  
Zhao Xia ◽  
Xin Kang
Keyword(s):  
Earth Pressure ◽  
Horizontal Stress ◽  
Granular Soils ◽  
Bender Element ◽  
Bender Elements ◽  
Soil Pressure ◽  
Pressure Transducers ◽  
Laboratory Investigations ◽  
Particle Size And Shape ◽  
Stress Dependent

The stress-dependent K0, Vs, and Vs anisotropy and their correlations with sand for 1D consolidation stress were tested with a custom-designed floating-wall consolidometer-type Bender Element (BE) testing apparatus. K0 of a soil sample was calculated using stress measurements through soil pressure transducers installed at the midsection of the consolidometer. The Vs and Vs anisotropy were measured by the bender elements installed in three orthogonal directions in the consolidometer, i.e., vh, hv, and hh. Granular soils with different sizes and shapes were tested. The effects of the stress level, overconsolidation ratio (OCR), particle size and shape on the Vs anisotropy, and K0 of the granular soils during one-dimensional consolidation were investigated. The laboratory investigations suggested (1) the K0 showed a constant value during loading, while it increased as the OCR increased during unloading, (2) soils with smaller particle sizes, rough surfaces, and angular geometry tended to have a lower value of K0, and vice versa, (3) both the anisotropic stress state and the anisotropic fabric (geometry) could lead to the Vs anisotropy, but the Vs anisotropy was manifested due to the horizontal stress-lock during unloading stage, and (4) the published correlation between Vs and K0 was modified by introducing the influence of the OCR, which could effectively reduce the variation and improve the prediction accuracy. Therefore, the modified correlation could be used as a robust approach to estimate K0 for both normally consolidated and highly overly consolidated granular soils.

Experimental characterization of deformation, coefficient of earth pressure at rest, stiffness, and contact force distributions of sand during secondary compression and rebound

2016 ◽  
Vol 53 (5) ◽  
pp. 889-898 ◽  
Author(s):  
Y. Gao ◽  
Y.-H. Wang
Keyword(s):  
Contact Force ◽  
Pressure Sensors ◽  
Earth Pressure ◽  
Horizontal Stress ◽  
Soil Behavior ◽  
Bender Elements ◽  
Secondary Compression ◽  
Comprehensive Picture ◽  
Shear Box ◽  
Deformation Coefficient

This paper aims to provide a comprehensive picture of the sand responses during secondary compression and rebound based on experimental characterizations. The experiment was carried out on dry Leighton Buzzard sand using a modified direct shear box equipped with tactile pressure sensors for the stress measurements and bender elements for stiffness (i.e., Ghv and Ghh) monitoring. It was found that secondary compression and rebound followed the same deformation trends as primary compression and rebound to continuously contract and expand, respectively. The deformation characteristics determined the changes in the associated soil properties; therefore, the opposite soil behavior during secondary compression and rebound was observed. During secondary compression, the corresponding void change, deviatoric strains εq, and the deviatoric strain rate [Formula: see text] increased with increasing vertical stress [Formula: see text] or deviatoric stress q because the sample crept more easily under a higher [Formula: see text] or q. The compression deformation gave rise to an increase in the horizontal stress [Formula: see text] and associated coefficient of earth pressure at rest K0. The soil stiffness also increased as the contact normal forces became more homogenized. During secondary rebound, the sample expanded unabated no matter whether [Formula: see text] was greater or smaller than [Formula: see text]. The corresponding void ratio change, εq, and [Formula: see text] increased with decreasing [Formula: see text] or q because the sample expanded more easily under a lower [Formula: see text] or q. The expansion gradually reduced [Formula: see text] along with the associated K0 value. The sample stiffness continued to decrease, and contact force homogenization was not observed.

scholarly journals Monitoring a 28.5 m High Anchored Pile Wall in Gravel Using Various Methods

Sensors ◽  
2019 ◽  
Vol 20 (1) ◽  
pp. 80 ◽  
Author(s):  
Ricardo Moffat ◽  
Pablo Parra ◽  
Miguel Carrasco
Keyword(s):  
Optical Fiber ◽  
Earth Pressure ◽  
Time Domain Reflectometry ◽  
Body Motion ◽  
Soil Pressure ◽  
Optical Time Domain Reflectometry ◽  
Excavation Process ◽  
Topographic Survey ◽  
Optical Time ◽  
Horizontal Displacements

Horizontal displacements of a multiple-anchor pile wall in a 28.5 m deep excavation using the top–down construction method have been monitored using optical fiber (Brillouin optical time-domain reflectometry (BOTDR)), strain gauges, inclinometers, and a topographic survey. This work presents a comparison between these different techniques to measure horizontal displacements in the pile at several stages of the soil excavation process. It was observed that displacements can be separated into two components: Rigid body motion and pile flexural deformation. Measurements using optical fiber and inclinometers are considered the most adequate and easy to install. A numerical model allows us to evaluate the influence of earth pressure on the estimated horizontal displacements. It is shown that using soil pressure on the wall given by p = 0.65Kaγh, on a simplified modeled wall, provides a close deduction of horizontal displacements compared to observed values on the field.

Study on Soil Pressure of High Fill Retaining Wall in Construction Stage

2012 ◽  
Vol 204-208 ◽  
pp. 718-721 ◽  
Author(s):  
Peng Li ◽  
Xiao Song
Keyword(s):  
Retaining Wall ◽  
Earth Pressure ◽  
Monitoring Data ◽  
Experiment Study ◽  
Pressure Monitoring ◽  
Soil Pressure ◽  
Construction Stage ◽  
The Earth ◽  
Pressure Calculation ◽  
Practical Guidance

The traditional formula using for the calculation of Expressway on high embankment of the retaining wall and the earth pressure can not be very good practical. In order to accurately determine the soil pressure calculation of the complex retaining wall in construction stage for guaranteeing the engineering safety, the experiment study on soil pressure is done, and the study on soil pressure monitoring data is also done. Then the valuable conclusions are obtained to facilitate better practical guidance for construction.

Evaluation of induced trench twin culverts constructed in deep fill

2020 ◽  
Vol 57 (9) ◽  
pp. 1388-1403
Author(s):  
Campbell Bryden ◽  
Kaveh Arjomandi ◽  
Arun Valsangkar
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Data Acquisition ◽  
Earth Pressure ◽  
Field Studies ◽  
Construction Method ◽  
Recent Criticism ◽  
Soil Pressure ◽  
Earth Pressures ◽  
Overburden Soil

When culverts are installed beneath high embankments, earth loads become excessive and the induced trench construction method is a viable design option to reduce the culvert loads to acceptable levels. However, limited field studies evaluating the performance of induced trench twin culverts are reported in the literature and the practicality and effectiveness of the induced trench construction method (in general) has been subject to recent criticism. This paper describes the performance of twin 3048 mm inside-diameter reinforced concrete culverts constructed with an induced trench beneath 15.3 m of fill. Research instruments and autonomous data acquisition systems were installed during construction to monitor (i) culvert earth pressures, (ii) embankment deformations, and (iii) groundwater elevations in the vicinity of the compressible fill. The experimental observations recorded throughout the construction phase are presented herein; the embankment deformations are indicative of effective positive arching within the induced trench region, and the average earth pressure at the culvert crown was reduced to approximately 48% of the overburden soil pressure. The experimental data are compared with those reported in the literature by others, and the conclusions attained from this study demonstrate the effectiveness of the induced trench construction method.

Coefficient of earth pressure at rest for sands subjected to vibration

2007 ◽  
Vol 44 (10) ◽  
pp. 1242-1263 ◽  
Author(s):  
Barames Vardhanabhuti ◽  
Gholamreza Mesri
Keyword(s):  
Lake Michigan ◽  
Earth Pressure ◽  
Horizontal Stress ◽  
Vertical Vibration ◽  
Vertical Stress ◽  
Dynamic Changes ◽  
Shearing Resistance ◽  
Interparticle Contacts ◽  
Horizontal Pressure ◽  
Stress Ratios

An oedometer instrumented to measure horizontal pressure was used to examine the behavior of the coefficient of earth pressure at rest, Ko, of clean sands subjected to vertical vibration. Reconstituted specimens of Ottawa, Lake Michigan Beach, and Niigata sands were used in a comprehensive series of tests. The dynamic effort is defined by the ratio of dynamic increase in effective vertical stress to the static effective vertical stress, and frequency and duration of vibration. Dynamic changes in Koare referenced to a series of lines representing the ratio of the increase in effective horizontal stress to the increase in effective vertical stress corresponding to different void ratios or friction angles through the Jaky equation. An increase in Kooccurs when the combination of the initial sand state and dynamic effort results in periodic disengagement of interparticle contacts, producing a periodic decrease in interparticle shearing resistance and thus a periodic fluidization of the sand. The highest values of [Ko]maxas well as the lowest values of eminwere obtained with dynamic stress ratios equal to or greater than 3–4. Vibration of overconsolidated sands results in an initial Kodrop that increases with previbration density and overconsolidation ratio. Thereafter, the behavior of Koand void ratio with vibration depend on the potential for fluidization.

Effects of wetting–drying and stress ratio on anisotropic stiffness of an unsaturated soil at very small strains

2009 ◽  
Vol 46 (9) ◽  
pp. 1062-1076 ◽  
Author(s):  
C. W.W. Ng ◽  
J. Xu ◽  
S. Y. Yung
Keyword(s):  
Unsaturated Soils ◽  
Stress Ratio ◽  
Shear Stiffness ◽  
Small Strain ◽  
Matric Suction ◽  
Bender Elements ◽  
Shear Moduli ◽  
Small Strains ◽  
Stiffness Anisotropy ◽  
Stress Dependent

The very small strain shear modulus of soil, G0, is affected by many factors including soil properties, current stress state, stress history, and matric suction. Very little research has been conducted on anisotropic shear moduli of unsaturated soils. In this study, the effects of wetting–drying and stress ratio on anisotropic shear stiffness of an unsaturated completely decomposed tuff (CDT) at very small strains have been investigated using a modified triaxial testing system equipped with three pairs of bender elements. During drying and wetting tests, the measured very small strain shear moduli increased in a nonlinear fashion, but at a reduced rate as the matric suction increased. Similar to the stress-dependent soil-water characteristic curves (SDSWCCs), there was hysteresis between the drying and wetting curves showing the variations in shear moduli with matric suction. Variation in suction on the specimens under isotropic conditions produced changes in stiffness anisotropy (expressed as G0(hh)/G0(hv)) together with anisotropic strains. In shearing tests at constant suctions, significant stress-induced stiffness anisotropy was observed due to a change in the stress ratio. While shearing at a constant stress ratio, G0(hh)/G0(hv) appeared to be constant.

scholarly journals Grain-scale DEM study of open-ended pipe pile penetration in granular soils

2021 ◽  
Vol 249 ◽  
pp. 11007
Author(s):  
Michail Komodromos ◽  
Gaël Combe ◽  
Gioacchino Viggiani
Keyword(s):  
Distinct Element ◽  
Horizontal Stress ◽  
Granular Soils ◽  
Pipe Pile ◽  
Pile Shaft ◽  
Offshore Engineering ◽  
Pile Penetration ◽  
Penetration Tests ◽  
Shed Light ◽  
Number Of Particles

Open-Ended Pipe Piles (OEPP) are particularly popular in offshore engineering. An important feature of the installation of these piles is the rate with which soil enters the pile from the bottom, and its interaction with the internal pile shaft. The response of OEPP crucially depends on the occurrence of soil plugging, which can make the behavior of an OEPP similar to a pile of solid cross section. Plugging is generally attributed to arching effects in the soil; therefore, understanding this phenomenon requires an investigation at the grain scale. This is precisely the objective of this study, where the Distinct Element Method (DEM) is used to study the installation of an Open-Ended Pipe Pile in a Virtual Calibration Chamber comprising 128000 grains, under constant horizontal stress. Despite the relatively small number of particles, this numerical model is found to be able to reproduce several aspects of the mechanisms actually observed in thefield. The results are compared to those obtained from actual experiments of miniature pile penetration tests. Stress and strainfields that develop in the soil inside and outside the pile provide interesting data and shed light on the mechanisms at play during OEPP installation, especially as for the influence of grains interlocking.

scholarly journals Stress Distribution in a Cohesionless Backfill Poured in a Silo

2014 ◽  
Vol 8 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Li Li ◽  
Jonathan D. Aubertin ◽  
Jean-Sébastien Dubé
Keyword(s):  
Soil Structure ◽  
Earth Pressure ◽  
Horizontal Stress ◽  
Density Variation ◽  
Direction Parallel ◽  
Rest State ◽  
Drop Mass ◽  
Drop Tests ◽  
Series Of Experiments ◽  
Infrastructure Rehabilitation

The field of infrastructure rehabilitation and development requires a better understanding of soil-structure interactions. The interaction behaviour between soil and structures has mostly been investigated through theoretical and/or numerical analysis. This paper presents a series of experiments performed on an intermediate-scale physical model made of an instrumented silo. In contrast to most reported laboratory tests, both the horizontal and vertical stresses were monitored during backfilling operations realised by wild pouring. Drop tests were performed to investigate the density variation with respect to the drop (or falling) height of the soil, which were introduced in the pressure interpretation. The results showed that horizontal stress in the direction parallel to the pouring plane is larger than that perpendicular to the pouring plane. Apparently, the vertical stress is well-described using the arching solution by considering the backfill in an active state, whereas the horizontal stress perpendicular to the pouring plane is better described with the arching solution by considering the backfill in an at-rest state. An estimate of the earth pressure coefficients based on the measured vertical and horizontal stresses indicates, however, that the backfill was closer to an at-rest state in the direction perpendicular to the pouring plane, whereas in the direction parallel to the pouring plane, it was in a state between at-rest and passive. These results indicate that it is important to measure both the horizontal and vertical stresses to obtain a whole picture of the state of the backfill. The results showed also that the horizontal stresses can be larger than those calculated by the overburden solution, probably due to dynamic loading by drop mass during the filling operation and stress lock.

Field Observation of Tide-Induced Loading Upon Undersea Tunnel

2012 ◽  
Author(s):  
Nan Chen ◽  
Guan-lin Ye ◽  
Jin-jian Chen ◽  
Xiao-he Xia
Keyword(s):  
Linear Relation ◽  
Nuclear Power ◽  
Cooling Water ◽  
Earth Pressure ◽  
Tidal Height ◽  
Tidal Level ◽  
Pressure Transducers ◽  
Power Stations ◽  
Earth Pressures ◽  
Type Pressure

Many shallow undersea tunnels have been built to circulate the cooling water for the thermal or nuclear power stations in recent years. In current study, a field monitoring of tide-influenced earth pressure on the tunnel was carried out by using the pad type pressure transducers. The variation of tidal level was also recorded carefully. The measured results of earth pressures and the tidal height were analyzed qualitatively and quantitatively. It can be found that there is a linear relation between the variation of load and tidal height. The computed values of the loadings based on tunnel pressure theory are almost the same with measurements.

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