Kenichi Soga

Kenichi Soga
University of California, Berkeley | UCB · Department of Civil and Environmental Engineering

About

537
Publications
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14,733
Citations

Publications

Publications (537)
Article
Full-text available
It is difficult to collect and characterise well-preserved samples of weakly cemented granular rocks as conventional sampling techniques often result in destruction of the cementation. An alternative approach is to prepare synthetic geomaterials to match required specifications. This paper introduces microbially induced carbonate precipitation (MIC...
Article
Finding a reliable and cost-effective approach to monitor the activities of the New Austrian Tunneling Method (NATM) tunnel construction automatically is a challenging yet important task. This study presents an interpretable artificial intelligence (AI) framework that automatically identifies NATM construction works using low-cost site surveillance...
Conference Paper
Full-text available
A seepage cutoff wall is one of the most common seepage mitigation measures in embankment dams and levees. Specifications for seepage cutoff walls are mainly performance-based, where criteria for determining performance are usually short-term hydraulic conductivity and/or strength parameters based on laboratory testing of field collected samples. H...
Article
Mesh-sensitivity of post-localisation analysis is an inherent drawback of continuum based finite element methods. Out of many available regularisation techniques, the nonlocal method has proved to provide viable solutions. It can be implemented at the constitutive level without adjusting equilibrium equations. This study aims to apply the nonlocal...
Article
Full-text available
Fluvial dikes are important engineering works for protecting river valleys from flooding, so the stability of them is of great importance. In this paper, we apply a two-point two-phase formulation of the Material Point Method (MPM) to investigate the dike stability problem under the action of overtopping flows. Such a method has been incorporated i...
Article
Full-text available
Brillouin scattering based fiber optic strain sensor is used to measure distributed strain profile of a structure for structural health monitoring. A distributed strain profile is derived from the Brillouin spectrum peaks but error is induced when a local strain change occurs in a distance scale smaller than the spatial resolution. In this study, a...
Article
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DOWNLOAD AT: https://authors.elsevier.com/a/1bMO339eM4BkU4 The infiltration of gas and water into the tunnel may cause serious safety problems and the control of leakage should not be underestimated in the design phase. Simulating the mechanical behaviour of longitudinal joints in segmented tunnel linings in a reliable manner serves not only from...
Article
Full-text available
Undrained deformation of dilative sand generates negative excess pore pressure. It enhances the strength, which is called dilative hardening. This increased suction is not permanent. The heterogeneity at the grain scale triggers localisations causing local volume changes. The negative hydraulic gradient drives fluid into dilating shear zones. It lo...
Article
Full-text available
Geologic reservoirs containing gas hydrate occur beneath permafrost environments and within marine continental slope sediments, representing a potentially vast natural gas source. Numerical simulators provide scientists and engineers with tools for understanding how production efficiency depends on the numerous, interdependent (coupled) processes a...
Preprint
Full-text available
Microbial-Induced Calcium carbonate (CaCO3) Precipitation (MICP) has been extensively studied for soil improvement in geotechnical engineering. The properties of calcium carbonate crystals such as size and quantity affect the strength of MICP-treated soil. This study demonstrates how the data from micro-scale microfluidic experiments that examine t...
Preprint
Full-text available
Microbial-Induced Carbonate Precipitation (MICP) has been explored for more than a decade as a promising soil improvement technique. However, it is still challenging to predict and control the growth rate and characteristics of CaCO3 precipitates, which directly affect the engineering performance of MICP-treated soils. In this study, we employ a mi...
Article
Full-text available
Numerous microbial species can selectively precipitate mineral carbonates with enhanced mechanical properties, however, understanding exactly how they achieve this control represents a major challenge in the field of biomineralisation. We have studied microbial induced calcium carbonate (CaCO3) precipitation (MICP) in three ureolytic bacterial stra...
Poster
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Methane hydrate, a form of clean energy also called combustible ice, has drawn a global interest as an alternative energy resource of traditional fossil energy. • The world's first offshore methane hydrate production test was conducted at the eastern Nankai Trough in Japan in 2013. A cumulative gas volume of 119,500 m 3 was continuously produced un...
Poster
Full-text available
Enhancement of the coupling model • Additional field simulation • Optimizing the production method to improve the efficiency of production and guarantee the safety of production • Modeling the coupling process • Verifying the model using laboratory data and field data • Implementing the simulation in the field work using the verified model and cali...
Poster
Full-text available
For reservoir thermal storage analysis: • Create python code that incorporates newly developed an analytical solution and conduct parametric study to show effects of model parameters on hot water recovery from doublet well system • Compare results of analytical solution with results of TOUGH and TReactMech model simulations • Develop engineering an...
Article
Full-text available
A new analytical model is proposed to estimate the peak impact pressure of debris flow exerted on a rigid barrier. The new model consists of two terms, $p=\alpha_1 \rho_0 g h_0 + 0.5 \rho_0 u_0^2$, accounting for static and dynamic impacting effects, respectively. The static coefficient $\alpha_1$ is determined according to equations governing the...
Conference Paper
Full-text available
Internal erosion is a potential failure mode of earth dams and levees and consists of the mobilization of solid grains as water flows through granular material. This paper focuses on the study of the suffusion mechanism in internally unstable soils. Typically these soils are broadly graded in nature, in which a finer fraction is subjected to erosio...
Conference Paper
The material point method (MPM) is a hybrid Eulerian-Lagrangian approach capable of simulating large deformation problems of history-dependent materials. While the MPM can represent complex and evolving material domains by using Lagrangian points, boundary conditions are often applied to the Eulerian nodes of the background mesh nodes. Hence, the u...
Conference Paper
Full-text available
Estimated geotechnical properties are unavoidably affected by various uncertainties. Quantifying the uncertainty in estimated geotechnical properties relies on probabilistic models adopted in the data analysis. Gaussian random field model (RFM) is one of the most prevailing models used in conventional geotechnical data analysis. A recent perceptibl...
Conference Paper
Full-text available
Ground Source Heat Pumps (GHSP) utilize the earth's shallow depths for storing and extracting heat during different seasons in the year. The installation and efficient operation of those geothermal energy systems requires an accurate prediction of their thermal performance. Numerical models are able to simulate the thermal performance accurately bu...
Conference Paper
Full-text available
Geothermal energy is being used as a sustainable alternative to conventional fossil fuels. An efficient utilization of geothermal sources requires a thorough understanding of subsurface conditions and their interaction with above-surface activities. Determination of uneven variation of temperature in the underground will help to efficiently utilize...
Article
This study investigates whether the heterogeneity of deepwater turbidite strata, particularly the layering and grainsize, could be contributing to catastrophic sand production during extraction of fluid from the subsurface through a wellbore. This type of sand production was seen from the producing interval over turbidite strata during the 2013 gas...
Poster
Landslide is a serious natural disaster, which often causes huge economic losses and even casualties. Obtaining the physical parameters of the landslide body is a very effective means of monitoring landslides. Traditional electromagnetic-based wireless underground sensor networks (EM-based WUSNs) technology, exposes several major defects in the lan...
Article
This study investigates the thermal and thermomechanical behavior of two energy piles with either double U-loop or spiral loop heat exchanger configurations. The piles were installed in a sandstone formation, and a heating-recovery-cooling-recovery cycle was applied to the piles. In both piles, the shaft resistance evaluated from the measured axial...
Technical Report
Full-text available
The Camp Fire, which began on November 8, 2018, provides an instructive case study of the size, scale, and costs of wildfire risk in California. This report summarizes findings from a Quick Response research study conducted with support from the National Science Foundation, administered through the Natural Hazards Center at the University of Colora...
Article
This paper presents a case study describing the effectiveness of multiple measures implemented to repair overdeformed metro shield tunnels in Shanghai. The changes in horizontal diameter were up to 3.6% of the tunnels’ diameters due to unexpected surcharge at the ground surface. The surcharge was removed, and then structural reinforcements were add...
Article
Well integrity is crucial in enabling sustainable gas production from methane hydrate reservoirs and real-time distributed monitoring techniques can potentially facilitate proper and timely inspection of well integrity during gas production. In this research, the feasibility of distributed fibre optic strain monitoring with Brillouin optical time d...
Article
The shallow subsurface of dense cities is increasingly exploited for various purposes due to the significant rise in urban populations. Past research has shown that underground activities have a significant impact on local subsurface temperatures. However, the resulting spatial variability of ground temperature elevations on a city-scale is not wel...
Preprint
In this paper, we describe a new scalable and modular material point method (MPM) code developed for solving large-scale problems in continuum mechanics. The MPM is a hybrid Eulerian-Lagrangian approach, which uses both moving material points and computational nodes on a background mesh. The MPM has been successfully applied to solve large-deformat...
Preprint
Full-text available
In this paper, we describe a new scalable and modular material point method (MPM) code developed for solving large-scale problems in continuum mechanics. The MPM is a hybrid Eulerian-Lagrangian approach, which uses both moving material points and computational nodes on a background mesh. The MPM has been successfully applied to solve large-deformat...
Preprint
Full-text available
The Material Point Method (MPM) is a hybrid Eulerian-Lagrangian approach capable of simulating large deformation problems of history-dependent materials. While the MPM can represent complex and evolving material domains by using Lagrangian points, boundary conditions are often applied to the Eulerian nodes of the background mesh nodes. Hence, the u...
Article
Full-text available
Fibre optic cables can be used as sensors to monitor temperature changes through the analysis of back scattered light. This can be linked to changes in the ambient conditions surrounding the fibre optic cable. Active distributed temperature sensing relies on an external heat source relative to the fibre optic cable to measure the properties of, and...
Article
Full-text available
Microbial-induced calcium carbonate (CaCO3) precipitation (MICP) has been explored for its potential engineering applications such as soil stabilization, but current understanding of the fundamental MICP processes at the microscale is limited. In this study, real-time in situ microscale experiments were conducted using glass slides and microfluidic...
Article
Post-slide investigations show large displacement of failed soil mass in many earthquake-triggered landslides. An Eulerian-based finite-element modelling (FEM) of large deformation of soil, for pseudostatic and dynamic loadings, is presented in this study. The Eulerian FEM is compared with Lagrangian-based explicit and implicit finite-element (FE)...
Article
Urbanization and limited land availability have resulted in the increased utilization of underground structures including residential basements in largely populated cities such as London, with an average addition of 200 basements per year in some boroughs. Residential basements kept at a comfortable temperature level throughout the year significant...
Article
Full-text available
In this paper we describe the design of a proof-of-concept wireless embedded sensor system for continuous strain cycle monitoring as a method for fatigue life assessment on civil structures. Monitoring of strain cycles is energy demanding, and therefore not suited to energy-constrained devices, as it requires continuous acquisition of strain data w...
Article
Full-text available
The objective of this study is to evaluate the effectiveness of MICP to improve the internal erosion resistance of gravel-sand mixtures. Two gravel-sand mixtures with 25% sand/75% gravel and 50% sand/50% gravel were used; the former was susceptible to suffusion whereas the latter was internally stable. MICP treatment was made by either mixing the u...
Article
Full-text available
Distributed fibre optic sensing (DFOS) presents several advantages over traditional point sensors, for measuring strain and temperature in civil and geotechnical infrastructure. DFOS techniques use light transmitted through an optical fibre to enable measurements to be taken all along an embedded or surface-mounted fibre optic cable, which can be u...
Article
The Centre for European Nuclear Research (CERN) uses large and complex scientific instruments to study the basic constituents of matter by operating a network of underground particle accelerators and appurtenant tunnels. Long-term safety and structural health of this critical infrastructure highlighted the need for a sensing plan that could provide...
Chapter
The recent advances in sensor and communication technologies are making significant impacts on the monitoring methods used for geotechnical engineering. This chapter introduces several emerging technologies that have shown to provide new types of dataset that were not available a decade ago. Technologies such as computed tomography scanning, enviro...
Article
Full-text available
The Centre for European Nuclear Research (CERN) uses large and complex scientific instruments to study the basic constituents of matter by operating a network of underground particle accelerators and appurtenant tunnels. Long-term safety and structural health of this critical infrastructure highlighted the need for a sensing plan that could provide...
Article
Full-text available
Distributed fibre optic sensing (DFOS) presents several advantages over traditional point sensors, for measuring strain and temperature in civil and geotechnical infrastructure. DFOS techniques use light transmitted through an optical fibre to enable measurements to be taken all along an embedded or surface-mounted fibre optic cable, which can be u...
Article
A real-time dynamic Brillouin optical time domain reflectometry (BOTDR) based system is introduced by using small gain stimulated Brillouin scattering with fast data managing and saving method. The system achieves 2cm read-out interval, 2m spatial resolution and about 7 ¼µ accuracy with about 7Hz or even faster with 23Hz continuous monitoring. A mo...
Conference Paper
Land deformation, such as land subsidence and landslides, is conventionally monitored using extensometers and inclinometers. Distributed fiber optic sensing is an emerging technology that transforms common telecommunication fiber optic cables into sensors capable of making distributed strain measurements at kilometer scales and beyond. Recently, th...
Conference Paper
A high content of salt in soil makes it unsuitable for crop production. In this study, a series of laboratory test was conducted to investigate the ability of bioremediation to reduce the salinity of soil samples. Saline soil was prepared after soaking the test soil in artificial seawater for 3 days and dried it. It was then mixed with different mi...
Conference Paper
Full-text available
Thousands of piles are built every year in the world and their construction has become an integral part of a building"s design and construction. Although so many piles are being built, contractors still find piles that are damaged or their as-built condition is significantly different than the initial design. Pile damage or any compromise in the st...
Chapter
Geophysical hazards, such as avalanches, debris flows and submarine landslides, involve rapid and large mass movement of granular solids, water and air as a multi-phase system. The momentum transfer between the discrete and continuous phases significantly affect the dynamics of the movement. This study aims to understand the ability of continuum mo...
Conference Paper
Full-text available
The primary focus of this research is to develop and implement an agent-based model (ABM) to analyze the New Orleans Metropolitan transportation network near real-time. ABMs have grown in popularity because of their ability to analyze multifaceted community scale resilience with hundreds of thousands of links and millions of agents. Road closures a...
Article
Full-text available
Experimental evidence indicates that the shear localisation acts as a precursor to the failure in biaxial compression tests of granular materials. Once formed they are persistent and lead to progressive failure of most geotechnical structures. It is generally accepted that the primary mode of deformation within these shear bands is simple shear whi...
Article
Full-text available
When saturated granular materials which are dilative in nature are subjected to the undrained deformation, their strength increases due to the generation of negative excess pore pressure. This phenomenon is known as dilative hardening and can be witnessed in saturated dense sand or rocks during very fast loading. However, experimental evidence of u...
Conference Paper
Full-text available
Field observations of infrastructure performance, during and following construction, are vital for efficient design of infrastructure in subsequent projects. Fibre optic sensing technology offers considerable benefits because it provides a continuous measurement profile along its length whereas conventional monitoring instrumentation, such as strai...
Poster
Full-text available
The finite element method suffers from pathological mesh dependency and numerical errors from lack of convergence during modelling of strain localisation. Standard constitutive models assume that mechanical behaviour at a point is dependent on the current deformation at that individual point only. In the event of a shear localisation, an individual...
Poster
Full-text available
Soil constitutive models play a prominent role in finite element predictions of geotechnical structures. The accuracy of these material models dictates the precision of the finite element predictions. Conventional constitutive models assume that the orientation of principal stresses coincides with that of principal plastic strain rate which is term...
Article
Long runout landslides can cause significant damage and represent one of the most important problems in geotechnical engineering. Understanding the mechanics of the landslide runout process is important for risk assessment and is challenging due to its complexities. This work examines the runout of the 22 March 2014 Oso, Washington, landslide. The...