Development Of Liquefaction Research Articles

Study on Liquefaction Resistance of Pile Group by Shaking Table Test

This study investigated the antiliquefaction property of the pile group. It is shown in the pore pressure ratio, pile acceleration, and bending moment response of saturated silt fine sand. The response law of pile acceleration and bending moment during liquefaction development is proved. The results show that liquefaction occurs in single piles, four piles, and six piles under the action of 0.35 g seismic wave. But the time of liquefaction is different. There is an obvious difference in the response of pile acceleration and bending moment during liquefaction. Liquefaction in the saturated silt fine sand develops from shallow to deep. The complete liquefaction of six piles takes the longest time, while the single pile takes the shortest time, and the average delay was 8.82 s. With the increase of the number of piles, there are some differences in pile acceleration, magnification factor, and pile bending moment, which are mainly reflected in time. The peak acceleration appearance of six piles was 3.08 s later than that of the single pile on average. The maximum bending moment appearance of six piles was 1.96 s later than that of the single pile on average. The acceleration and bending moment of the pile begins to attenuate when the pore pressure ratio increases. It shows that the saturated silt fine sand has softening and damping effect before liquefaction. In summary, the antiliquefaction performance of the pile group is better than that of a single pile. In the seismic design of pile foundation in liquefied soil, the antiliquefaction performance of the pile group is better.

Factors of competitiveness of LNG export projects

As a result of the development of liquefaction, storage, transportation and regasification technologies, the attractiveness of LNG projects is steadily growing — in some cases, such projects are becoming more competitive than traditional pipeline solutions. The range of solutions for natural gas liquefaction projects is very wide, but low-tonnage LNG provides greater mobility and high speed of project implementation, cause of the usage of the simple low-efficiency technologies. Medium-capacity natural gas liquefaction plants can be built in environment where there are not enough resources to create a large-capacity project, and enable the usage of relatively small and remote fields, including off shore areas. For Russia, an important advantage of medium-tonnage technologies is that they can be developed in a relatively short time. The positive experience of government support for LNG exports in Canada is noteworthy. The government of this state strives to create conditions for environmentally responsible energy production and use, while ensuring the growth of the Canadian economy, as well as the availability of reliable and competitive energy sources and the protection of energy infrastructure. As for the portfolio of orders for Russian projects for natural gas liquefaction, for example, at present, in the Yamal-LNG project, Russian orders account for only 30 %, and the goal is at least 70 %. To achieve this goal, government support is required: concessional lending and tax incentives. For LNG production in the Arctic zone of the Russian Federation, with the support of the state Corporation Rosatom, a bench-testing base for import-substituting equipment is being created in the Nizhny Novgorod region. Government support for LNG projects should also include improving the regulatory framework. Russia is taking an important step towards developing its hydrocarbon reserves in the Arctic. Special attention should be paid to the measures of state support that are provided to exporters in the context of the pandemic, including in the field of LNG sales, in particular, ensuring sustainable lending to the real sector of the economy with the provision of state guarantees and subsidies.

Stability analysis of soil liquefaction using a finite element method based on particle discretization scheme

Mathematically, liquefaction corresponds to the unstable solutions of the governing equations of soil dynamics. Stability analysis of these solutions facilitates the understanding of the triggering and development of liquefaction. This paper presents a numerical approach for stability analysis of the solutions of the governing equations. The governing equations are linearized for small perturbations and discretized using a finite element method (FEM) based on the particle discretization scheme (PDS). By solving the discretized governing equations with the developed PDS–FEM code, unstable solutions are captured for perturbations in the form of a three-dimensional spherical wave. The present approach considers the dilatancy effect and the detaching effect. The numerical results show that the dilatancy effect triggers and the detaching effect spatially expands the unstable solutions. The existence and expansion of the unstable solutions provide a new perspective on the triggering and development of liquefaction.

Experimental Evaluation of p-y Curves Considering Development of Liquefaction

AbstractAlthough evidence in the literature indicates that the lateral p-y resistance of piles in liquefiable soils is significantly reduced, the shape and amplitude of the reduced p-y curve during pore pressure buildup are needed for reliable design of pile foundations. To investigate this issue, a single steel pile embedded in homogeneous saturated Nevada sand was subjected to sequential dynamic shaking and lateral (inertial-equivalent) loading. A key goal in the test program was to develop a data set capable of rendering insight into the characteristics of p-y resistance under developing liquefied soil conditions. As such, results presented focus primarily on the static p-y curves backcalculated from bending moment distributions at the achieved excess pore pressures. Analysis of the experimental data shows that mobilization of the partially liquefied soil was achieved during lateral loading. A rich set of test data was produced from this testing series, which will be useful for model validation and sub...

Coal liquefaction policy in China: Explaining the policy reversal since 2006

China has emerged as a leader in coal liquefaction. While the country's abundant coal resources and acute concerns about oil security help explain China's interest in liquefaction, the driving forces for this industry are complicated and policy has been inconsistent. Since 2006 Beijing has tried to slow down the development of liquefaction; even as China has become more dependent on imported oil, the central government has been wary about the large impact of liquefaction technologies on scarce resources such as water. However, local government officials in coal rich areas have strong incentives to pour investment into the technology, which helps explain the uneven development and policy. The future of coal liquefaction will depend on how these forces unfold along with major Beijing-led reforms in the Chinese coal industry, which is closing smaller mines and favoring the emergence of larger coal producing firms. Those reforms will have mixed effects on liquefaction. They temporarily contribute to higher prices for coal while over the longer term creating coal companies that have much greater financial and technical skills needed to deploy technologies such as coal liquefaction at a scale needed if this energy pathway is to be competitive with conventional sources of liquid fuel.

Pseudo-static analysis of piles in liquefiable soils

In this paper, pseudo-static analysis of piles in liquefying soils is applied to a case study of a bridge foundation. The response of piles is separately evaluated for the cyclic phase during the intense shaking and development of liquefaction, and for the subsequent lateral spreading phase. With regard to the considerable uncertainties involved in predicting liquefaction and lateral spreading phenomena the effects of key parameters influencing the pile response are examined through parametric analyses. Particular attention is given to the variation in stiffness and residual strength of the liquefied soil, the magnitude of lateral ground displacement and the magnitude of inertial loads from the superstructure. The results shed light on the relative importance of key parameters for different combination of loads and ground conditions, and allow comparative evaluation between loads on the pile exerted by the crust layer and the liquefied layer.

Liquefaction and displacement of saturated sand under vertical vibration loading

In order to investigate the influence of the vertical vibration loading on the liquefaction of saturated sand, one dimensional model for the saturated sand with a vertical vibration is presented based on the two phase continuous media theory. The development of the liquefaction and the liquefaction region are analyzed. It is shown that the vertical vibration loading could induce liquefaction. The rate of the liquefaction increases with the increase of the initial limit strain or initial porosity or amplitude and frequency of loading, and increases with the decrease of the permeability or initial modulus. It is shown also that there is a phase lag in the sand column. When the sand permeability distribution is non-uniform, the pore pressure and the strain will rise sharply where the permeability is the smallest, and fracture might be induced. With the development of liquefaction, the strength of the soil foundation becomes smaller and smaller. In the limiting case, landslides or debris flows could occur.

NEDOL coal liquefaction development for supplying transportation fuels

NEDOL coal liquefaction development for supplying transportation fuels

Stress-strain transformations and liquefaction of sands

Presented in this paper are the results of the laboratory tests of sands performed for the purpose of defining the characteristics of the dynamic shear stress-shear strain relationships. For this purpose, the transformation of the initial stress-strain characteristics of undrained saturated sands was investigated separately. These transformations take place under conditions of an increase in pore pressure under the effect of sufficiently intensive dynamic excitations. The process of occurrence and development of liquefaction was investigated simultaneously. The obtained results show that the transformation of the stress-strain relationships leads to intensive reduction in the initial dynamic characteristics of sands. At the moment of occurrence of initial liquefaction, for the selected strain, shear moduli are considerably reduced in respect to their initial values. These parameters tend to be further reduced in the phase of post-initial liquefaction. It is concluded that the process of liquefaction of sands can be completely defined through the transformation of the stress-strain relationships.

Postearthquake Deformation Analysis of Wildlife Site

Postearthquake deformations of the Wildlife site, Imperial Valley, Calif., following the 1987 Superstition Hills earthquake, have been interpreted by finite-element deformation analyses. The analyses consider the stress redistribution and reconsolidation caused by the development of liquefaction. The stress redistribution analysis was conducted under fully undrained condition to consider the effects of strain-softening behavior of liquefied materials. The reconsolidation analysis was conducted using Biot's theory to consider the effects of dissipation of excess pore-water pressures. The results reveal that the delayed pore-water pressure response and deformation may be due to the redistribution of stresses and pore-water pressures.

Liquefaction at the Meloland Overcrossing During the Imperial Valley Earthquake of 1979

The Meloland Overcrossing is located 0.3 mi from the Imperial fault and was shaken by ground surface motions of up to 0.3 g during the Imperial Valley earthquake of 1979 (magnitude M = 6.4). While there was no significant damage to this instrumented highway bridge or any reported surface evidence of subsurface liquefaction, it is assessed that liquefaction occurred in up to three layers at the site at various times during the first eight seconds of shaking. A modified level ground liquefaction analysis after Seed and others (1983) was used to assess such time dependent development of liquefaction. Results from such evaluations were used to assess and explain anomalies in the lateral and rotational responses of the central pier pile foundation demonstrating that the central pier of the Meloland Overcrossing came periously close to complete collapse during this event. This is contrary to the bridge designer9s belief that this highway bridge performed quite well during the earthquake as characterized solely by the lack of observable damage to the bridge. It is further suggested that the time dependent evaluation of liquefaction demonstrated herein can be used on other projects where one likewise wishes to assess the amount of deformation (e.g., the rotationally induced settlement in the case of Meloland) that is likely to ensue.

Development of liquefaction and gasification in the Federal Republic of Germany

A number of pilot plants for coal gasification are run in the F.R.G. Two pilot plants for liquefaction are under construction. Furthermore, a number of plans exist for commercial plants. Probably the Federal Government, after a thorough examination, will sponsor only few of these projects. Decision is still pending and it is in fact difficult to assess the value of the individual new processes objectively. Certain technical data from life tests are still lacking. Furthermore, available coal qualities and intended use for oil and gas are important criteria for assessments. In the near future, however, the possibility and the necessity will help to decide and to place priorities. With increasing prices for oil and natural gas, the processes for coal liquefaction and gasification become relatively economic, so that with reference to the market conditions decisions can be made according to the criteria that apply to private enterprises. The best possible solution to the future problems of energy supply can only be found by joint efforts of government and industry on a national and international scale.

Rise and Development of Liquefaction of Gases.

Rise and Development of Liquefaction of Gases.