Integral stability and lining stability of the twin-tube tunnel are lower than that of the single tunnel,and the mechanical performance during excavation is more complex.In this paper FLAC3D is used to analyze the integral behavior of the twin-tube tunnel, cosidering to different excavation cross-section and nonideal construction quality.Conclusions are made from the analysis of the caeculated stress,displacement and axial force of the cable.It is helpful to the design and construction of the twin-tube tunnel in China.

Integer Behavior Analysis of Twin-tube Tunnel during Excavation with Fast Lagrangian Analysis of Continua in 3 Dimensions

Numerical evaluation of slope effect on soil–pile interaction in seismic analysis

Evaluation of Seismic Performance of Takahama Wharf Using Nonlinear Effective Stress Analysis

A 1D-modelling approach for simulating the soil-pile interaction mechanism in the liquefiable ground

Slope effect on dynamic p–y backbone curve in dry sand

Evaluation of the soil–pile interface properties in the lateral direction for seismic analysis in sand

The input parameters for numerical simulation of the liquefaction phenomenon need to be properly evaluated from laboratory and field tests, which are difficult to be performed in practical situations. In this study, the numerical simulation of the cyclic direct simple shear test was performed to analyze the applicability of Finn and PM4Sand models among the constitutive models for liquefaction simulation. The analysis results showed that the Finn model properly predicted the time when the excess pore water pressure reached the maximum, but failed to simulate the pore pressure response and the stress-strain behavior of post-liquefaction. On the other hand, the PM4Sand model properly simulated those behaviors of the post liquefaction. Finally, the evaluation procedure and the equations of the input parameters in the PM4Sand model were developed to mach the liquefaction cyclic resistance ratio corresponding to design conditions.

Evaluation of Input Parameters in Constitutive Models Based on Liquefaction Resistance Curve and Laboratory Tests

Various liquefaction vulnerability indices (LVIs) have been proposed to quantify the severity of liquefaction, and used to create the liquefaction hazard map. In producing the liquefaction hazard map, the spatial variability of LVI is important because the number of available in-situ data is typically limited, and the values at the unmeasured locations are predicted using kriging operations that consider the spatial correlation of observed values. In addition, the liquefaction hazard map may vary significantly depending on how LVI was spatially interpolated. This study aims to evaluate the spatial variability of soil properties based on cone penetration test (CPT) data, and to investigate the changes in geostatistical properties of LVIs depending on shaking intensity. A simplified CPT-based procedure was used to calculate the factor of safety against liquefaction, and the geostatistical properties of LVI according to shaking intensity were evaluated using the parameters of semivariogram. In addition, the LVIs at unmeasured locations were predicted using two geostatistical modeling approaches, and their results were compared to investigate the accuracy of geostatistical approaches in predicting LVIs according to the peak ground acceleration (PGA).

Geostatistical Properties of Liquefaction Vulnerability Index for Reclaimed Land in South Korea

As a method of ground reinforcement to prevent liquefaction, various construction methods have been applied. A method to stabilize the ground using a fixative or stabilizer is the most useful method for the reinforcement of construction against liquefaction for lower levels of existing structures. However, the vertical or inclined grouting that is generally applied to construction sites has drawbacks in efficiency and reinforcement range as well as drilling problems at the bottom of existing structures. To overcome these drawbacks, some equipment and reinforcement methods that can conduct grouting after digging underneath of existing structures in the horizontal direction have been developed. As a foundational study to develop the above technology, this study conducted a dynamic finite differential analysis (FLAC 2D) to compare and review the effects of liquefaction reinforcement methods using the grouting method. As the analysis results, the horizontal grouting method is considered more effective to reduce liquefaction occurrence than applying the slope and vertical reinforcement conditions.

Byeong-Soo Yoo

Papers

Evaluation of the soil–pile interface properties in the lateral direction for seismic analysis in sand

Evaluation of Input Parameters in Constitutive Models Based on Liquefaction Resistance Curve and Laboratory Tests

Slope effect on dynamic p–y backbone curve in dry sand

Geostatistical Properties of Liquefaction Vulnerability Index for Reclaimed Land in South Korea

Numerical study of effectiveness of horizontal grouting in liquefaction mitigation for existing building foundation