Louis Ge

Louis Ge
National Taiwan University | NTU · Department of Civil Engineering

Ph.D.

About

95
Publications
22,752
Reads
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1,241
Citations
Introduction
I am a professor in the Department of Civil Engineering at National Taiwan University. My research work focuses on granular mechanics, including soil liquefaction, tensile strength of compacted soil, ground improvement, and cyclic constitutive modeling. In geotechnical engineering practice, I also work on deep excavation and microtunneling. If you have any inquiries, please feel free to contact me at louisge@ntu.edu.tw
Additional affiliations
August 2015 - present
National Taiwan University
Position
  • Professor
September 2011 - June 2012
Missouri University of Science and Technology
Position
  • Professor (Associate)
August 2011 - July 2015
National Taiwan University
Position
  • Professor (Associate)
Education
January 2001 - December 2003
University of Colorado Boulder
Field of study
  • Civil Engineering
August 1997 - December 2000
University of Colorado Boulder
Field of study
  • Civil Engineering
October 1991 - June 1995
National Taiwan University
Field of study
  • Civil Engineering

Publications

Publications (95)
Article
The material point method (MPM) is an extended finite element method used to simulate large deformation scenarios. A massive translational landslide in Taiwan was adopted to validate the numerical technique for thorough investigations, including the digital terrain models (DTMs), laboratory experiments, and numerical analyses were available in a fo...
Article
Full-text available
The random finite element method has been widely used to evaluate slope uncertainty and reliability. To determine the probability of failure, the safety factor sampling often involves the Monte Carlo method. This process is a time-consuming task that requires many computational resources. In this study, we propose a pretrained model to directly est...
Article
According to historical records, the soil in the Xinhua District of Tainan City, Taiwan, has been liquefied several times in 1946, 2010, and 2016. To assess the soil liquefaction resistance and understand the recurring liquefaction mechanism of this site, this study conducts a series of experimental tests, including the undrained dynamic triaxial t...
Article
Full-text available
The objective of this study is to quantify the effect of the spatial variability of soil properties on site response and ground motion coherency. A 2D random field theory is used to simulate soil parameters, including shear wave velocity (Vs) and nonlinear stress–strain curves. Different levels of spatial variability are controlled by coefficient o...
Article
Full-text available
This paper proposes a method for estimating the effective zone, including effective depth and effective range of compaction degree, from rapid impact compaction (RIC) on sand layer whose fines content is less than 10%. The proposed method utilizes a string of microelectromechanical system accelerometers to monitor the acceleration at various depths...
Article
A large earthquake may lead to the generation of excess pore water pressure in soils. With the increasement of excess pore water pressure, the stiffness degradation may lead to noticeable levels of deformation even without liquefaction. More than 20 cyclic triaxial tests were conducted in this study to investigate the stiffness degradation of soils...
Article
Full-text available
To investigate the rock particle breakage behavior subject to impact load, a series of split Hopkinson pressure bar (SHPB) tests were conducted on selected Nishan rock and Shoushan rock particles within gravel size range at different strain rates. Both rock particles exhibit a typical strain softening macrobehavior and their dynamic peak strengths...
Article
Full-text available
The paper presents a numerical study on the void ratio of a ternary mixture of similar ellipsoids. The effect of particle size distribution on the void ratio was investigated through samples of various volume fractions of large, medium, and small particles. The particle size ratio of large, medium, and small particles is 16:4:1. The ratio between t...
Article
Calibrating an advanced constitutive model is not a trivial task. Conventionally, a linear regression is used to calibrate a constitutive model using laboratory data; however, it is not sufficient to identify model parameters. Optimization methods can be used to calibrate the parameters of an advanced constitutive model. The optimization methods, i...
Article
This study focused on slope stability behaviors under different conditions, including gravity, rainfall, and earthquake. The slope models were prepared by mixing sand (80%) and clay (kaolinite, 20%) and compacting at optimum water content. Under the gravitational condition, the model tests were performed with three different directions of a gravel...
Article
Investigating the permeability characteristics of sand-foam mixtures in different conditioning states is important not only in earth pressure balance (EPB) shield tunneling and standstill but also for post-tunneling soil handling. Slump and permeability tests were carried out on poorly graded sand that was conditioned with different foam injection...
Article
Soil liquefaction can occur when the strength and stiffness of soil are reduced by changes in the stress condition, and the settlement of structures can be affected by this phenomenon following an earthquake. To evaluate the liquefaction-induced settlement of structures, a simple equation that proposed the concept of equivalent viscosity of soil-wa...
Article
Geotechnical systems often examine interactions that occur between continuum bodies and granular soils. The systems and interactions can be accurately simulated by using multiscale coupling approaches. The model for the continuum bodies is often constructed into a mesh. The meshing, however, is time consuming for a huge spatial system and if distor...
Article
The common laboratory tests for determining the tensile strength of soils can be categorized into direct and indirect methods. For direct methods, there are no standard testing apparatuses or procedures to measure the tensile strength of soils. This paper presents a modification of a direct tension apparatus and its test results on compacted soil....
Article
Full-text available
This study applies system identification methods to analyze the change in the dynamic characteristics (fundamental frequency and damping ratio) of rocking foundation systems under earthquake excitation. Shaking table testing performed at the National Center for Research on Earthquake Engineering of Taiwan on a rocking-governed column-footing model...
Article
This study reported the investigation on the small strain modulus of compacted low plastic Mississippi River Valley silt under varying moisture contents and dry densities through ultrasonic pulse velocity testing method. Detailed procedures on filtering the ultrasonic pulse velocity signals and determining the wave arrival times were established. T...
Article
The critical state and steady state theories are widely accepted for simulating the soil behavior and providing a basis for liquefaction evaluation and constitutive modeling. However, there was conflicting evidence regarding the critical state and steady state of sands in the last decades. In some cases, the critical state and steady state are take...
Article
An indentation test was developed to indirectly determine the effective tensile strength of lightly cemented sand by iterative method. The description of the test is followed by a discussion and comparison of the determination of the effective tensile strength of soil under a framework proposed in previous research. Test results reveal that, in gen...
Article
Clay clogging frequently happens during tunneling with an earth pressure balance (EPB) shield in clayey ground and results in local disk cutter housings. It could even completely clog shield chambers with a blocked cutterhead. Dispersants are commonly adopted as conditioning agents to reduce clay stickiness, which is related to clay consistency det...
Chapter
This paper presents an examination the Aso-bridge slope subjected to the foreshocks of the 2016 Kumamoto earthquakes. While the Aso-bridge slope was marginal stable in the absence of earthquake, it remained stable during the foreshocks that struck on April 14 and 15 2016, with magnitudes of 6.5 and 6.4 Mw, respectively. To validate that the slope d...
Article
Due to low strength and high compressibility, soft clay should be improved to increase its strength, and decrease the permeability and the ground settlement for a better construction condition. Nowadays the sustainability is much more important, so recycled materials such as fly ash and slag have been widely used and replaced the part of cement in...
Article
Unlike the liquefaction potential assessment, the liquefaction-induced ground settlement has not been studied extensively. The uncertainty of the ground profile and associated soil engineering properties is the major challenging to advance the current knowledge on this subject. Within Ishihara and his colleagues’ framework, the liquefaction-induced...
Article
This paper presents a case study and numerical simulations regarding a large-scale deep excavation in Central Jakarta, Indonesia, and its three-dimensional (3D) effects on wall deformation. The soil profile in Central Jakarta is generally soft to firm alluvial clay overlying stiff to hard alluvial and diluvial clay. In this study, the geotechnical...
Article
Full-text available
Nowadays, a wide range of site planning, field investigation and slope analysis need to be carried out for slope protection and landslide-related disaster reduction. To enhance the efficiency of topography modeling, unmanned aerial vehicle (UAV) has become a new surveying technique to obtain spatial information. This study aims to determine the top...
Chapter
As only a few boreholes are present along a tunnel design alignment, geological understanding of the worksite may not be adequate and the ability to optimise the tunnelling parameters is thus limited. Since this lack of boreholes will cause a significant potential of geo-hazards for tunnelling works. This study proposes an alternative method to det...
Conference Paper
A study was conducted on cemented sand modeled with a contact bond model to investigate the influences of micro parameters on its macro properties based on a three dimensional discrete element simulation. The influences of the micro parameters of the stiffness ratio, the strength ratio and the friction coefficient on the unconfined compression beha...
Article
The permeability is a very important property affecting drainage, pore pressure buildup and dissipation, and ground settlement for saturated sand during and after seismically induced liquefaction. A laboratory experiment was developed to conduct tests for evaluating the water movements and permeability in a sand column before, during and after liqu...
Article
Full-text available
In urban area with soft clay deposit, it is required that the wall deformation of a deep excavation be limited to a very low value in order to minimize damages to adjacent buildings. Major factors that control the magnitude of wall deformation includes excavation depth, shear strength of soft clay, stiffness of bracing system, and flexural rigidity...
Chapter
Low-plasticity silt has been found susceptible to liquefaction in recent earthquake reconnaissance. As silt is less permeable than sand, a different excess pore water pressure dissipation mechanism could take place. This may have an effect on the cyclic strength at different loading rates, although the influence on loading rate is neglected in gene...
Article
The spatial variability of geotechnical parameters is determined in terms of their scale of fluctuation (SOF), θ. There are basically two approaches in analyzing the spatial variability of geotechnical parameters in order to determine their SOF. One uses an autocorrelation function (ACF) from random field theory and time series analysis and the oth...
Conference Paper
Full-text available
Pipe jacking force mainly consists of the penetration resistance from face pressure and the friction resistance between the pipe and soil. Jacking forces depends on several site related parameters such as alignment, pipe diameter, soil type, groundwater table, overburden, overcut, lubrication, steering corrections, and stoppage. This paper presents...
Article
In the past two decades, significant progress has been made in understanding the thermo-hydro-mechanics of unsaturated soils. Constitutive models have been developed and validated, experimental techniques have been further refined, and full-scale and centrifuge model tests are being successfully conducted. Unsaturated soil mechanics is also being a...
Article
A contact mechanics model, based on the Hertzian elastic contact theory and cementation coating development, was established to 6 predict the time-dependent small-strain stiffness of fly ash–stabilized soils during curing. The cementation coating development model was 7 developed at the particulate level based on the Arrhenius law. A hyperbolic tim...
Article
Minimum and maximum void ratios provide a general basis for comparative evaluation of material properties for soils with various densities. Either the minimum or the maximum void ratio is dependent considerably upon the fines content of soil. There are a few mathematical models in the literature for predicting the variation of minimum void ratio wi...
Article
Radial strain behaviors and stress state interpretation methods of silica sand consolidated at different K0 values under modified direct simple shear were investigated in this research. Consolidated drained triaxial compression test, direct shear box test, and wire reinforced direct simple shear tests were conducted and the test results were compar...
Conference Paper
For understanding and modeling the behavior of saturated sand during liquefaction, the permeability of the sand is a very important property affecting drainage, pore pressure buildup and dissipation, and ground settlement. A laboratory experiment system was developed to conduct tests for evaluating the water movements and permeability in a sand col...
Article
Full-text available
Gravel deposits are materials that contain large particles. The mechanical behavior of such materials is conventionally examined using large-scale tests such as large-scale triaxial and in situ shear tests. However, the large-scale tests may not fully represent the gravel deposits in the field or cannot obtain the deformation parameters. This study...
Article
Strain-controlled cyclic simple-shear tests were performed on silica sand with radial strain measurements. The specimens were tested under a constant K0 condition and subjected to cyclic loading and postcyclic monotonic loading. Threshold cyclic shear strain, volumetric strain, secant shear modulus, and damping ratio are investigated. Generally, th...
Article
The effectiveness of Class-C fly ash (FA) (ASTM C-618) and lime kiln dust (LKD) used in clay pavement base materials stabilisation has been investigated in this research. Proctor compaction test, unconfined compression test, and non-destructive test (Briaud compaction device (BCD) modulus and thermal conductivity) were carried out on the chemically...
Article
Full-text available
Many underground excavation failures are caused by severe water inflow due to the piping through the opening in the diaphragm wall. The opening can be created by slurry pocket or air pocket during concrete placement by tremie method. This type of defect in diaphragm wall can be detected by sonic logging to show the condition of trench wall and by m...
Article
An enhanced series-parallel (S-II) model of one-dimensional conductive heat flow through a unit cell was developed to estimate the time-dependent thermal conductivity of Class C fly ash stabilized soils. The unit cell is composed of three separate heat flow paths: a continuous path through solid contacts (soil contacts, fly ash contacts, and soil f...
Article
Silty sand liquefaction has been of great interest of research in geotechnical earthquake engineering, especially for the silty sand containing a large amount of non-plastic fines. This article presents a case study on non-plastic silty sand liquefaction. A new sampling technique, Gel-Push sampler, that could retrieve undisturbed non-plastic silty...
Article
Soft clays are widely distributed in Missouri, United States. Due to their relatively low strength and high compressibility, subgrade construction in soft clays has encountered many difficulties. In recent practice, the use of fly ash (FA) along with lime to tackle soft subgrade problems has shown promising results. The effectiveness of Class C FA...
Article
The use of correlations and empirical relationships in geotechnical engineering provides a fast, cost-effective means of predicting the value of a parameter based on the values of certain other, possibly more easily determined, parameters. The correlation between two or more soil properties has been found to be dependent in varying degrees on soil...
Article
Full-text available
Silica gel, a typical desiccant widely used in industry to absorb moisture, is a porous inert colloid with different sizes in beaded or angular shape. The mixture of silica gel and pore fluid of matched refractive index has been used as transparent media to mimic the behavior of sand. Previous studies have been focused on the static properties of t...
Book
Selected papers from the proceedings of the Geo-Hubei 2014 International Conference on Sustainable Civil Infrastructure, held in Yichang, Hubei, China, July 20-22, 2014. Sponsored by the China Three Gorges University, the Committee on Sustainability of ASCE, and the Geo-Institute of ASCE. Geotechnical Special Publication 248 contains 13 peer-review...
Article
Full-text available
Expansive clays exhibit a high potential for the volume change behavior when the soil moisture changes. The estimated annual cost of the damage to the facilities built on expansive clay in the United States exceeds 9 billion dollars. Because of the physicochemical nature of the expansive clay, the use of chemical agents to improve their engineering...
Conference Paper
Full-text available
Small strain stiffness of granular materials is important to many engineering applications, such as earthquake engineering, pavement, machine foundation, embankment subjected to tidal impacts, and foundations for structures under wind loads. Shear wave velocity, which is an indicator of stiffness, was measured with a newly developed bender element...
Article
Rock slopes undergoing long–term effects of weathering and gravity may gradually deform or creep downslope leading to geological structures such as bend- ing, bucking, fracturing, or even progressive failure. This study uses geomechanics-based numerical modeling to qualitatively explain the cause and evolution of slope creep behavior. Constitutive...
Article
Full-text available
Single-well and group-well pumping tests were undertaken in a deep gravel formation of the Taipei basin to determine the hydraulic parameters and better understand the drawdown characteristics across the basin. The periodic drawdown fluctuation due to tidal loading from the overlying river resulted in a difficulty in determining the hydraulic param...
Conference Paper
Full-text available
For a complete probabilistic characterization of a geotechnical parameter, its mean, variance, and the scale of fluctuation have to be known. While the mean and variance can be easily determined, determination of the scale of fluctuation is a little more complex. Knowledge of the scale of fluctuation is important in reliability-based design as it i...
Article
Full-text available
Because low-compacted trench backfill around a manhole is normally liquefiable, the manhole could suffer uplift damage associated with soil liquefaction during a strong earthquake. In this study, 22 dynamic centrifuge models were tested to investigate the response of a buried manhole subjected to a dynamic load. The models were tested under 20g, an...
Article
A survey of current literature has revealed that the testing protocol for determining the time of setting of fly ash-soil mixtures is not available. Although the current ASTM standard recommends using the Vicat needle method with a water-to-fly ash weight ratio of 0.35, it was originally proposed for testing the time of setting of cement. The curre...
Conference Paper
When a conventional method such as linear regression is insufficient to identify the constants and parameters of an advanced constitutive model, numerical optimization techniques are often used. In employing numerical optimization to constitutive model calibration, an objective function essentially needs to be formulated in the form of nonlinear le...
Article
Full-text available
Because of the large grainsizes typical of railroad ballast, large triaxial samples are required to assess the reactions of these materials. The parallel gradation modeling technique was originally developed by John Lowe in 1964 to allow assessment of large grain-size geomaterial properties in smaller, more typical testing facilities. Emphasis has...
Article
Mode I (tensile) fracture is the most commonly observed failure in geostructures resulting from cracks in soil. Direct or indirect tensile tests have been used to evaluate the tensile strength of geomaterials. In this paper, the unconfined penetration device and experimental procedure were modified to reduce measurement errors. It was then used to...
Article
The response of a soil-structure system subjected to monotonic or cyclic loading is significantly influenced by the mechanical behavior of its interface. In this paper, the friction characteristics of crushed rock-concrete interface and the role of the crushed rock deformability were examined through a series of monotonic and cyclic direct shear te...
Conference Paper
Full-text available
The knowledge of the spatial variability of geotechnical parameters, which can be described statistically by the mean, the variance, and the scale of fluctuation, is important in reliability-based design. Of particular importance is the scale of fluctuation. It can be used to compute the variance reduction factor, a factor of spatial averaging of g...
Book
Proceedings of the GeoHunan International Conference II: Emerging Technologies for Design, Construction, Rehabilitation, and Inspection of Transportation Infrastructure, held in Hunan, China, June 9-11, 2011. This Geotechnical Special Publication contains 42 papers addressing contemporary geotechnical subjects. Topics include: physical, numerical,...
Conference Paper
The response of a soil-structure system subjected to monotonic or cyclic loading is influenced significantly by the mechanical behavior of soil-structure interface. In this paper, the friction characteristics of the crushed rock-concrete interface and the role of the crushed rock deformability were examined through a series of monotonic and cyclic...
Conference Paper
Pre-consolidation pressure provides valuable information about soil behavior and, specifically, settlement under an induced load. Soil is expected to have less settlement before its pre-consolidation pressure and much more settlement after that point. The pre-consolidation pressure and the compressibility of the soil can be determined from the resu...
Conference Paper
Developing reliable and versatile constitutive models for geomaterials has been challenging tasks for nonlinear finite element analysis of geotechnical engineering systems. The fuzzy set plasticity theory has been developed to account for the nonlinear soil stress-strain response under complex stress paths. The theory in many ways resembles the bou...
Conference Paper
In pile foundation response due to horizontal vibration, it is known that the original Novak's method overestimates the dominant frequency and underestimates the dominant amplitude of pile head responses. It is found that reducing the pile-foundation system stiffness and damping coefficients would lead to a smaller dominant frequency and higher dom...
Conference Paper
Full-text available
A soil variability analysis is presented in this paper. About 317 unconsolidated undrained triaxial compression tests (UU) were carried out on undisturbed samples from four locations in Missouri. The spatial variation of the undrained shear strength and plasticity index was described by the second-moment statistics (mean and variance). Meanwhile, t...
Conference Paper
Full-text available
Description of the spatial variation of compositional and mechanical soil parameters is often paramount in site characterization of geotechnical design and analysis. The values of the parameters themselves largely depend on in-situ state factors which are related to spatial locations. Also, for large-scale engineering projects such as earth dams or...
Conference Paper
When a conventional method such as linear regression is insufficient to identify the constants and parameters of an advanced constitutive model, numerical optimization techniques are often being used. In employing numerical optimization to constitutive model calibration, an objective function essentially needs to be formulated in such way that the...
Article
Three dynamic centrifuge models were tested to obtain data for safety evaluation of the Jen-Yi-Tan Dam in Taiwan subject to a strong earthquake. In these tests, recorded 1999 Chi-Chi earthquake ground motions were modified and used on the electro-hydraulic shaking table mounted on the 400 g-ton centrifuge at the University of Colorado at Boulder. A...