Poro-Elasto-Plastic Model for Wave-Induced Liquefaction

2014 ◽  
Author(s):  
Chengcong Liao ◽  
Hongyi Zhao ◽  
Dong-Sheng Jeng
Keyword(s):  
Two Dimensional ◽  
Plastic Model ◽  
Centrifuge Tests ◽  
Pore Pressures ◽  
Proposed Model ◽  
Progressive Waves ◽  
Plastic Components ◽  
Excess Pore Pressures ◽  
Wave Induced ◽  
Pore Pressure Build Up

In this study, a two-dimensional poro-elasto-plastic model for the wave-induced liquefaction in a porous seabed was presented. Two mechanisms of the wave-induced pore pressures were considered. Both elastic components (for oscillatory) and the plastic components (for residual) were integrated to predict the wave-induced excess pore pressures in marine sediments. The proposed 2D poro-elasto-plastic model allows for the pore pressure build-up process in a sandy seabed. The proposed model overall agreed well with the previous wave experiments and centrifuge tests. Numerical example shows that the pattern of progressive waves -induced liquefaction gradually changed from 2D to 1D.

Poro-Elasto-Plastic Model for the Wave-Induced Liquefaction1

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
C. C. Liao ◽  
H. Zhao ◽  
D.-S. Jeng
Keyword(s):  
Pore Pressure ◽  
Marine Sediments ◽  
Plastic Model ◽  
Whole Process ◽  
Centrifuge Tests ◽  
Pore Pressures ◽  
2D Pattern ◽  
Plastic Components ◽  
Excess Pore Pressures ◽  
Wave Induced

In this paper, we presented an integrated numerical model for the wave-induced pore pressures in marine sediments. Two mechanisms of the wave-induced pore pressures were considered. Both elastic components (for oscillatory) and the plastic components (for residual) were integrated to predict the wave-induced excess pore pressures and liquefaction in marine sediments. The proposed two-dimensional (2D) poro-elasto-plastic model can simulate the phenomenon of the pore pressure buildup and dissipation process in a sandy seabed. The proposed model overall agreed well with the previous wave experiments and geo-centrifuge tests. Based on the parametric study, first, we examined the effects of soil and wave characteristics on the pore pressure accumulations and residual liquefaction. Then, a set of analysis on liquefaction potential was presented to show the development of liquefaction zone. Numerical example shows that the pattern of progressive waves-induced liquefaction gradually changes from 2D to one-dimensional (1D), while the standing wave-induced liquefaction stays in a 2D pattern in the whole process.

Inclined Perimeter Drains Performance as Liquefaction Countermeasure Techniques Below Existing Buildings

2020 ◽  
Vol 14 (03) ◽  
pp. 2050015
Author(s):  
Samy Garcıáa-Torres ◽  
Gopal Santana Phani Madabhushi
Keyword(s):  
Pore Pressure ◽  
Structural Damage ◽  
Excess Pore Pressure ◽  
Existing Buildings ◽  
Ground Shaking ◽  
Vertical Drains ◽  
Centrifuge Tests ◽  
Pore Pressures ◽  
Excess Pore Pressures ◽  
Excess Pore

Reducing the risk of structural damage due to earthquake-induced liquefaction in new and existing buildings is a challenging problem in geotechnical engineering. Drainage countermeasure techniques against liquefaction have been studied over the last decades with an emphasis on the use of vertical drains. This technique aims to allow a rapid dissipation of excess pore pressures generated in the soil during the earthquake thereby limiting the peak excess pore pressures and consequently improve the structural response. Rapid drainage in the post-earthquake period in the presence of these drains helps quick recovery of the soil strength. Recent studies propose different variations in the vertical drains arrangement to improve the excess pore pressure redistribution in the soil around structures. However, conventional arrangements for existing buildings do not achieve an adequate proximity from the drains to the soil below the foundation. To address this, the performance of inclined and vertical perimeter drain arrangements are studied in this paper. Dynamic centrifuge tests were carried out for the different arrangements in order to evaluate the excess pore pressure generation due to ground shaking and the following dissipation together with the foundation settlement and dynamic response.

scholarly journals Downdrag Measurements on a 160-Ft Floating Pipe Test Pile in Marine Clay

1972 ◽  
Vol 9 (2) ◽  
pp. 127-136 ◽  
Author(s):  
M. Bozozuk
Keyword(s):  
Skin Friction ◽  
Compressive Load ◽  
Marine Clay ◽  
Positive Skin ◽  
Negative Skin Friction ◽  
Pore Pressures ◽  
Excess Pore Pressures ◽  
Test Pile ◽  
Excess Pore

Large negative skin friction loads were observed on a 160 ft (49 m) steel pipe test pile floating in marine clay. The test pile was driven, open-ended, on the centerline of a 30 ft (9 m) high granular approach fill on the Quebec Autoroute near Berthierville. Since the installation was made in 1966 the fill has settled 21 in. (53 cm), dragging the pile down with it. Negative skin friction acting along the upper surface of the pile was resisted by positive skin friction acting along the lower end as it penetrated the underlying clay. Under these conditions the pile compressed about [Formula: see text] (2 cm). Analysis of the axial strains indicated that a peak compressive load of 140 t developed at the inflection point between negative and positive skin friction 73 ft (22 m) below the top of the pile. Negative and positive skin friction acting on the upper surface of the pile exceeded the in situ shear strength and approached the drained strength of the soil where excess pore water pressures had dissipated. At the lower end where the positive excess pore pressures were high and relative movement between the pile and the soil was large, the positive skin friction approached the remoulded strength as measured with the field vane. Skin friction was increasing, however, as positive escess pore pressures dissipated.This paper shows that skin friction loads are related to the combination of (a) in situ horizontal effective stresses, (b) horizontal stresses due to embankment loads, and (c) horizontal stresses due to differential settlement of the fill.

scholarly journals Sustainable Measures for Protection of Structures Against Earthquake Induced Liquefaction

2021 ◽  
Author(s):  
Gopal S. P. Madabhushi ◽  
Samy Garcia-Torres
Keyword(s):  
Soil Liquefaction ◽  
Excess Pore Pressure ◽  
Economic Losses ◽  
Element Analysis ◽  
Centrifuge Testing ◽  
Centrifuge Tests ◽  
Liquefiable Soil ◽  
Recent Earthquakes ◽  
Excess Pore Pressures ◽  
Excess Pore

AbstractSoil liquefaction can cause excessive damage to structures as witnessed in many recent earthquakes. The damage to small/medium-sized buildings can lead to excessive death toll and economic losses due to the sheer number of such buildings. Economic and sustainable methods to mitigate liquefaction damage to such buildings are therefore required. In this paper, the use of rubble brick as a material to construct earthquake drains is proposed. The efficacy of these drains to mitigate liquefaction effects was investigated, for the first time to include the effects of the foundations of a structure by using dynamic centrifuge testing. It will be shown that performance of the foundation in terms of its settlement was improved by the rubble brick drains by directly comparing them to the foundation on unimproved, liquefiable ground. The dynamic response in terms of horizontal accelerations and rotations will be compared. The dynamic centrifuge tests also yielded valuable information with regard to the excess pore pressure variation below the foundations both spatially and temporally. Differences of excess pore pressures between the improved and unimproved ground will be compared. Finally, a simplified 3D finite element analysis will be introduced that will be shown to satisfactorily capture the settlement characteristics of the foundation located on liquefiable soil with earthquake drains.

Advanced Approaches for Coupled Deformation-Seepage-Analyses of Suction Caisson Installation

2017 ◽  
Author(s):  
Marc Stapelfeldt ◽  
Britta Bienen ◽  
Jürgen Grabe
Keyword(s):  
Deformation Analysis ◽  
Numerical Techniques ◽  
Suction Caisson ◽  
Large Deformation Analysis ◽  
Centrifuge Tests ◽  
Calculation Results ◽  
Modelling Techniques ◽  
Explicit Solver ◽  
Excess Pore Pressures ◽  
Numerical Approaches

In this paper the installation procedure of suction caissons is investigated by means of coupled seepage large deformation analysis performed with finite element methods. The modelling techniques employed to enable simulations of the penetration of a caisson into the soil under offshore conditions, i. e. several tens of meters below the water level. The numerical model includes a u-p-formulation, which is used to calculate the excess pore pressures and effective stresses from the total stresses. The Coupled-Eulerian-Lagrangian (CEL) approach available in conjunction with the Abaqus/Explicit solver is used. The calculation results are compared to centrifuge tests that were carried out recently at the Centre for Offshore Foundation Systems (COFS). This sheds light on the potential and the limitations of the presented numerical techniques. This paper concludes with a brief discussion of alternative numerical approaches that could be capable of the simulation of caisson installation.

Theoretical Tire Model Considering Two-Dimensional Contact Patch for Force and Moment

2021 ◽  
Author(s):  
Y. Nakajima ◽  
S. Hidano
Keyword(s):  
Finite Element Method ◽  
Shear Force ◽  
The Self ◽  
Slip Angle ◽  
Force Distribution ◽  
Two Dimensional ◽  
Tire Model ◽  
Side Force ◽  
Contact Patch ◽  
Proposed Model

ABSTRACT The new theoretical tire model for force and moment has been developed by considering a two-dimensional contact patch of a tire with rib pattern. The force and moment are compared with the calculation by finite element method (FEM). The side force predicted by the theoretical tire model is somewhat undervalued as compared with the FEM calculation, while the self-aligning torque predicted by the theoretical tire model agrees well with the FEM calculation. The shear force distribution in a two-dimensional contact patch under slip angle predicted by the proposed model qualitatively agrees with the FEM calculation. Furthermore, the distribution of the adhesion region and sliding region in a two-dimensional contact patch predicted by the theoretical tire model qualitatively agrees with the FEM calculation.

Preventive maintenance optimization for repairable products considering two-dimensional warranty and customer satisfaction

2018 ◽  
Vol 233 (4) ◽  
pp. 553-566
Author(s):  
Yukun Wang ◽  
Yiliu Liu ◽  
Aibo Zhang
Keyword(s):  
Customer Satisfaction ◽  
Preventive Maintenance ◽  
Product Performance ◽  
Maintenance Optimization ◽  
Two Dimensional ◽  
Maintenance Strategy ◽  
Minimal Repair ◽  
Proposed Model ◽  
Useful Life ◽  
Practical Implications

Customer satisfaction with a purchased product is closely related to the product performance within the warranty region and even the performance during the remainder of its useful life. Every satisfied customer may boost the future sales of the same product with positive evaluations and recommendations to others, and thus will create more profits for the manufacturer. During the useful life of the product, the expected cost to the manufacturer normally depends on the warranty policy, product reliability and specific servicing strategies implemented. In this article, considering the effect of customer satisfaction on the manufacturer’s incurred cost, we investigate a periodic and imperfect preventive maintenance strategy for repairable products sold with a two-dimensional warranty policy. The customer satisfaction is measured with the probability of the customer making a repeat purchase from the same manufacturer. In the proposed model, the number of preventive maintenance actions and corresponding maintenance level are jointly derived with the objective of minimizing the expected total cost per product to the manufacturer. The performance of the proposed preventive maintenance strategy is compared with that of minimal repair corrective maintenance strategy in a numerical example, so as to illustrate its applicability. In addition, some practical implications from a detailed sensitivity analysis are elaborated.

Numerical analysis of strengthening by rockfill embankments on an upstream tailings dam

2013 ◽  
Vol 50 (4) ◽  
pp. 391-399 ◽  
Author(s):  
Linda Ormann ◽  
Muhammad Auchar Zardari ◽  
Hans Mattsson ◽  
Annika Bjelkevik ◽  
Sven Knutsson
Keyword(s):  
Finite Element ◽  
Minimum Cost ◽  
Tailings Dam ◽  
Consolidation Process ◽  
Downstream Side ◽  
Pore Pressures ◽  
Staged Construction ◽  
The Stability ◽  
Excess Pore Pressures ◽  
Excess Pore

The consolidation process could be slow in an upstream tailings dam; therefore, the stability can reduce due to an increase in excess pore pressures when the dam is raised. The safety of the dam can be enhanced by constructing rockfill berms on the downstream side. This paper presents a case study on the strengthening of an upstream tailings dam with rockfill berms. The finite element analyses were performed for modelling the staged construction of the dam and for optimizing the volume of the rockfill berms. The dam was raised in 11 stages; each stage consisting of a raising phase and a consolidation phase. The study shows that the slope stability of the dam reduced due to an increase of excess pore pressures during the raising phase. The stability of the dam was successfully improved by utilizing rockfill berms as supports on the downstream side. A technique has been presented to minimize the volume of the rockfill berms so that the required stability can be achieved at minimum cost. This paper shows that the finite element method can be a useful tool for modelling the consolidation behaviour of an upstream tailings dam and minimizing the volume of the rockfill berms that may be needed to maintain the stability of the dam during staged construction.

Sign in / Sign up

Export Citation Format

Share Document