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The deep-seated landslides often caused severe hazard due to the large area and landslide mass associated with the landslide movement. Thus, monitoring the landslide movement is an important task for landslide hazard management. The Microelectromechanical Systems (MEMS) technique developed rapidly in recent years provides the ability of low-cost sensors and easy installation for monitoring of the landslide movement in field. Typically, the landslide movement monitoring using MEMS is based on the tilt angle determined from the measured ground acceleration variations in three directions, and being subjected to the signal noise. We adopt Moving Window Fast Fourier Transform and other seismic wave analysis in this study to improve resolution of the seismic signals and achieve a sound detection of deep-seated landslide movement. The MEMS was installed at the Lantai deep-seated landslide study area, which measured the ground accelerations mid-slope of the landslide. The seismic signals recorded for eleven earthquake events and three heavy rainfall events are selected for analysis. It was found that the signal frequency can be separated from the system responses and related to the landslide movement. Validations were conducted by comparing the analysis results to the field monitoring data of in-place inclinometer and borehole extensometer while available. It is suggested that the landslide movement can be identified with seismic signal at approximately 17 Hz, and the results are consistent for both earthquake-induced and rainfall-induced events.

Modern high-rise buildings may be configured into spaces of widely varying specifications. This situation creates a diverse building environment with multiple variables that make fire hazards difficult to predict and monitor accurately. Therefore, developing and implementing an integrated fire disaster prevention system is necessary in order to effectively prevent fire disasters and adequately protect life and property. In Taiwan, the response to an organization of fire prevention and disaster relief as well as evacuation planning and rescue guidance continue to rely primarily on human-provided intelligence. This method makes disaster-response decision-making inherently prone to error due to the inaccuracy, incompleteness, and poor communication of this intelligence. However, Building Information Modeling (BIM) and wireless sensor networks have been widely discussed in many aspects of building disaster-prevention management as approaches to increasing the accuracy and effectiveness of disaster-response decision-making. The present study uses BIM to construct a BIM-based Intelligent Fire Prevention and Disaster Relief System. This system integrates information on personal localization, on evacuation/rescue route optimization with Bluetooth-based technology, and on a mobile guidance device to create an intelligent and two-way fire disaster prevention system framework that displays the real-time and dynamic fire information in three dimensions (3D). The results of applying the BIM-based system demonstrate that it may effectively provide 3D visualization to support the assessment and planning of fire safety, to provide early detection and alarm responses, to direct efficient evacuation, and to facilitate fire rescue and control efforts in order to increase overall building safety and disaster-response capabilities.

This paper proposes a novel method of constructing objective functions, known as the robust and interpolation-free technique (RIFT), to be used in conjunction with inverse analysis. RIFT is free of interpolation and can avoid errors introduced by interpolation. Numerous validations performed using various functional forms, levels of data-density contrast, and data discrepancies demonstrate that RIFT is accurate and robust. The advantage of RIFT over the commonly used least-squares objective function is demonstrated. In addition, the applicability of RIFT as an objective function in inverse analysis is verified in two synthetic geotechnical engineering applications: laboratory tests and an excavation.

This paper discusses how small-strain stiffness and some aspects of the yield surface affect the finite-element predictions of excavation responses, including wall and ground deformations. By using the in-house-developed constitutive model SC1SS, it is possible to isolate and quantify impacts brought about by selected aspects of the soil behavior. This soil model has been validated to reasonably model Taipei silty clay and deep excavations in such soil. This study shows that ignoring small-strain stiffness can overestimate deformations by as much as 80%, leading to conservative and costly design. Inclined yield surface and Lode-angle dependency (on deviatoric planes) have lesser effects on the prediction results. In addition, the mechanisms behind these impacts are investigated through numerical triaxial tests.

Landslide is always not hazard until mankind development in highly potential area. The study not only tries to map deep seated landslide but also monitoring before the initiation of landslide. Study area in central Taiwan is selected and the geological condition is slate. Major direction of bedding in this area is northeast and the dip ranges from 30° to 75° to southeast. Several deep seated landslides were discovered in the same side of bedding from rainfall events. Several methods such as DEM observation, optical image identification, DInSAR, and monitoring instrumentations are adopted in this study. Landslides in study area are easy to observed from DEM observation and previous traditional elevation survey. However, the activity of landslides should be carefully taken into consideration. Thus SAR data utilization is adopted in this case. DInSAR and SBAS sar analysis are used in this research and ALOS/PALSAR from 2006 to 2010 is adopted. DInSAR analysis shows that landslide is possible mapped but the error is not easy to reduce. The error is possibly form several conditions such as vegetation, clouds, vapor, etc. To conquer the problem, time series analysis, SBAS, is adopted in this research. The result of SBAS in this area shows that large deep seated landslides are easy mapped and the accuracy of vertical displacement is reasonable. Moreover, a landslide area is selected to verify landslide activity in study area. Mems accelerometer is designed to monitor both static and dynamic behavior of this study area. Several events have been observed not only from rainfall but also from earthquake.

The volume of monitoring data is expected to increase exponentially in the near future. To cope with large volume of data, an information system was designed using concepts of distributed computing and service orientation. The system design consists of five discrete services, and it leads to a flexible, reliable, and scalable information system. One major challenge for this design is how to configure it properly. This work proposes the use of reliability assessment to answer such challenge. Three critical aspects for such information systems are assessed. They are reliabilities of data storage, data transmission, and server under load. Methods to estimate these reliabilities are presented and discussed. These discussions should help system administrators use quantified indices to configure information systems of distributed nature.

As an integral part of modern civil engineering systems, automated monitoring systems provide quantitative monitoring data for disaster-prevention, as references for future designs, and for forensics working at the site of an engineering disaster, among other possibilities. Most of these applications, however, require integration of the environment, sensor-deployment, and the monitoring data to realize the data's potential. This work proposes a visualization system that integrates monitoring information systems, three-dimensional digital field models, interactive computer graphics, and visualization techniques for the visualization of monitoring data along with field models. Testing of the developed system with undergraduate construction engineering majors showed a consistent improvement in efficiency of about 50% in the interpretation of monitoring data using the developed visualization versus conventional 2D maps and bar charts. The system enables users to interpret monitoring data effectively and intuitively, reduces misinterpretation, improves communication efficiency, and facilitates efficient decisions that are supported by the collected monitoring data.

The maintenance planning of deteriorating bridges is to find a balance between obtained performance and incurred cost. Because the planning horizon spans tens of years, a certain amount of uncertai...

Earthquake induced dip-slope sliding or rock-block sliding is usually analyzed using friction angles or friction coefficients measured at the sliding interface. A tilt test is a convenient test for measuring the required friction angle. However, a tilt test is a test under static conditions, and the applicability of measured friction parameters to analyze slopes under dynamic excitation requires further discussion. This study conducts a static tilt test and a dynamic shaking table test to simulate block sliding with base excitation, compares differences in measured sliding thresholds, and discusses the cause of these differences. Tests on three different materials (aluminum, sandstone, and synthetic sandstone) show that friction coefficients measured by tilt tests are always larger than the ones derived by shaking table tests. Moreover, high frequency tests yield larger friction coefficients, suggesting the sliding threshold is non-constant under excitation. In addition, tests with varying normal stresses on the sliding block show that with increasing contact stresses, sliding thresholds decrease, implying that sliding threshold varies with normal stress. Instantaneous friction coefficients, μi(t), during sliding are also studied in this work. It has been found that frictional behavior of synthetic sandstone deviates from the idealized Coulomb friction model. The instantaneous friction coefficient varies with relative displacement and relative velocity during sliding. Finally, reasons for differences between a static tilt test and a dynamic shaking table test are discussed. This study preliminarily identifies the limitations of the tilt test when applied to dynamic problems, and concludes that realistic sliding thresholds can only be obtained using dynamic tests such as shaking table tests.

In contrast to hard rocks, weak rocks often have significant shear-induced volumetric contraction/dilation under short-term or long-term loadings, and this behavior necessitates the development of an unconventional constitutive model. As such, an elastic–viscoplastic constitutive model characterizing the mechanical behavior of weak rocks is proposed, and its validity is demonstrated by comparing the simulated and the actual deformational behaviors of weak sandstone under various stress paths. In order to distinguish the immediate and the time-dependent deformation, the procedures involving multi-stage loading–unloading and creep tests, together with controlled pure-shear stress path, have been undertaken to clarify the deformation behavior of sandstone. Through these experimental procedures, elastic and viscoplastic deformations can be effectively separated, and the coupling between shear stresses and volume stresses can also be identified. Consequently, it is found that the function form of yield surfaces can also be applied to plastic potentials and viscoplastic potentials so that the complexity of the constitutive model to be developed is significantly reduced. Furthermore, the parameters for the proposed constitutive model can be readily obtained by fitting experimental data. Through systematic comparisons of the predictions and the actual behaviors of the studied sandstone, it is found the proposed constitutive model is capable of describing the elastic, plastic, and viscoplastic deformational behaviors not only under pure shearing stress path that were used to calibrate parameters, but also under other stress paths.

When geo‐materials, such as soil, gravelly soil and soft rocks, are loaded by shear stress, they frequently exhibit volumetric deformation, either dilation or compression, that cannot be modeled by conventional elasticity of isotropic material. This study aims, using as few parameters as possible, to develop a material model designed to simulate the main deformation of geo‐materials. A constitutive model based on the concept of shear‐induced anisotropic degradation is proposed. The proposed constitutive model is characterized by the following features: (1) significant shear‐induced volumetric deformation prior to failure, (2) modulus stiffening under hydrostatic loading and degradation under shearing; (3) stress‐induced anisotropy; and (4) being versatile in representing many geo‐materials and their behaviors under various stress paths. In the proposed model, the deformational moduli, E, G, and G ', vary according to stress state. The stiffening and degradation of these moduli render the deformat...

Automated monitoring systems are important in civil engineering industry. Existing utilities and infrastructures are monitored when their safety is of concern. These monitoring data also provide key indicators for their health and information for the life cycle management. With the prevalence of wireless sensor network (WSN) technology and the availability of various wireless communication technologies, large-scale automated monitoring systems can be deployed easily, and the cost of such systems are dropping owing to the use of Micro-Electro-Mechanical System (MEMS) technology. In this work, potential technologies for next-generation automated monitoring systems are first visited. A scalable IT (Information Technology) infrastructure for supporting large-scale automated monitoring systems capable of handling multiple projects is then proposed. Scalability, reliability, and extensibility are main considerations when designing the system and when choosing the technology for the system. Some scenarios are presented to demonstrate the characteristics and capabilities of the proposed infrastructure and information systems.

Macroscopic mechanical properties of sandstones, such as uniaxial compressive strength and Young's modulus were found to be significantly affected by their petrographic properties, e.g. the porosity n and the grain area ration GAR . The intricate relationship between the macroscopic properties of sandstones and their petrographic or microscopic properties necessitates further study in exploring how the microscopic properties influence the macroscopic mechanical behavior. In this research, numerical analyses based on the bonded-particle model, the microscopic properties of which originated from the bonded strength and stiffness, were thus conducted as a systematic study aiming at unraveling these microscopic mechanisms. A series of tests was conducted, and the results were compared with the actual behavior of sandstone. A numerical model comprised of three types of particles, grain particles GP , matrix particles MP and porous matrix particles PP , was accordingly proposed to represent the sandstone. The results of analyses demonstrated how the petrographic parameter GAR and porosity n determined the proportions and the numbers of GP , MP and PP . The strength and stiffness of these bonds were estimated based on back analyses. Accordingly, the results of parametric study indicate that matrix particles tend to have stronger bonding strength yet softer stiffness, when compared to the grain particles.

Weak sandstones possess deformational behavior different from hard rocks; these phenomena include shear dilation and softening of the deformational moduli. It has been found previously that under hydrostatic loading, the bulk modulus increases as confining pressure arises; and that under shear loading, the weak sandstone may transform from its original isotropy to a stress-induced anisotropic material, and the deformational modulus can accordingly be softened as well. These phenomena contribute to the increase of crown settlements during tunnel excavations, and account for several cases of tunnel squeezing. Consequently, a model capable of simulating major deformational characteristics of weak sandstones is needed for engineering purposes. A simple yet innovative constitutive model is accordingly proposed. This proposed model is characterized during the simulation as having: (1) non-linear volumetric deformation under hydrostatic loading; (2) significant shear dilation prior to the failure state; (3) isotropic stiffening of deformational moduli under hydrostatic loading; and (4) anisotropic softening of deformational moduli under shearing condition. The proposed model was formulated based on the linear elastic model, and it accounts for the variations of moduli E and G through different loading conditions. It was found that the proposed model is able to closely simulate the actual deformational characteristics of weak sandstones. In addition, the proposed model only needs six material parameters, and all these parameters can be easily obtained from experiments. This model was then incorporated into a finite element program and was used to analyze a squeezing tunnel case.

Time-dependent deformation behavior of rocks has a significant impact on the stability of rock slopes or underground constructions. This paper presents systematic experimental data regarding time-dependent deformation of a typical weak sandstone, known as the Mushan sandstone. The observed deformations are further separated to distinguish elastic and viscoplastic behaviors of the weak sandstone through the use of multi-staged loading–creep-unloading–reloading tests. The stress path is designed to be a purely hydrostatic loading followed by a pure shear, so that the deformations induced by these two types of stresses can be distinguished. For elastic behavior, although the nonlinear stress–strain relations vary according to the applied hydrostatic stress, these stress–strain relations can be normalized by the applied hydrostatic stress or the bulk modulus and converted into a single consistent stress–strain curve. Inelastic behavior is then obtained by subtracting the elastic deformation from the total deformation. As a result, the characteristics of the viscoplastic deformation are that: (1) the direction of the viscoplastic flow is time independent, and (2) it has a similar direction to the conventionally defined plastic flow. As such, the viscoplastic potential has a similar shape to the plastic potential, but the size of the former changes with time, while the latter has a size that is time independent. Meanwhile, through the calculation of irreversible work, direct evidence of orthogonality between the yield surface and the plastic flow, as well as the viscoplastic flow, is observed. Thus, it is reasonable to assert that the yield surface, the plastic potential, and the viscoplastic potential all have the same geometry. Consequently, the associated flow rules are applicable to modeling the time-dependent deformational behavior of weak sandstones.

Owing to tectonic collision, about 70% of Taiwan’s land are mountains and foothills. With several unfavourable conditions such as typhoons, strong rainfalls, and earthquakes, the landslide hazard is a critical issue in Taiwan. This issue is increasingly important because the use of hillsides for residence are growing in recent years. To address the issue and to protect its citizens, Taipei City Government initiated a pilot project to monitor landslide displacements in 2010. The project involves a selected hillside community with dip slope in Taipei City. The community had a major landslide in 1983.The monthly monitoring with non-automated devices is not helpful for residence to react to landslides. To help improve the situation, we use motion sensors to develop fully automated devices to infer displacements. We also used numerical analyses to help determine the best locations to install these devices. They were mounted to the ground surface to sense the tilt. The tilt converts to displacements by assuming slip surfaces. Small displacements were detected during a typhoon event in July of 2013.With the developed monitoring device, standard operation procedures were developed accordingly. Community residents has been educated how to react to unfavourable conditions. These conditions are defined by displacements exceeding certain thresholds.

This paper describes a numerical study of drained pressuremeter tests in sand using a one-dimensional finite-element method in conjunction with an advanced soil model MIT-S1, and input parameters corresponding to Toyoura sand. This soil model is capable of describing realistically the transitions in peak shear strength parameters of cohesionless soils that occur due to changes in void ratio and confining pressure. The predicted peak shear strengths can be normalized, at least approximately, by introducing a state parameter that references the initial (preshear) void ratio to the value occurring at large strain critical state conditions at the same mean effective stress. The numerical analyses idealize the pressuremeter test as the expansion of a cylindrical cavity and ignore disturbance effects caused by probe insertion. This idealization is relevant to self-boring pressuremeter tests. Results confirm that there is a linear correlation between the in situ (i.e., preshear) state parameter of the soil and the gradient of the log pressure-cavity strain expansion, as first suggested by Yu in 1994 using a much simpler soil model. Indeed, the linear coefficients derived for Toyoura sand differ only slightly from those obtained previously by Yu for six other sands.

Localization (position tracking) inside tunnels is difficult. GPS signal is not available inside tunnels, and installation of wireless access points is expensive. In this work, we propose the use machine vision for localization in tunnels. The advantage for such approach is that it requires no installation of any infrastructure, needed with radio triangulation approach. Prior researches have shown that machine vision can successfully identify positions in both outdoor and indoor environments. However, such application has never been tried inside tunnels. In this paper, we present our work on developing appropriate algorithms for localization in tunnels. One potential application for localization in tunnels is to help tunnel maintainers acquire accurate location information in tunnels when they do tunnel

Parameter or system identification is a useful tool in civil engineering. They have wide applications across many disciplines. However, due to the lack of generalpurpose tools for such analyses, researchers need to develop their own codes with duplicated efforts. Yet, it is sometime difficult to adopt other people’s code due to different modeling methods used. Thus, there is a need for general-purpose tools to resolve problems of this kind. This paper describes a general-purpose system for such purpose. The system has three features. First, it uses cloud-computing technology to provide large-scale capabilities. Second, the system uses a JavaScript engine for developing extensions. Third, it employs multi-objective particle swarm optimization for its applicability on wide range of problems. These features allow the system provide general capabilities to solve problems with similar needs. The design is validated and demonstrated by identifying constitutive model parameters in geotechnical engineering.

Typical engineering design processes involve an initial design, followed by iterations of analyses, interpreting and evaluating analyses results, and proposing new design or modifying existing design. The final design often results from intuitions obtained during this iterative process. Most computer-aided engineering (CAE) software focuses on the computer-aided analysis by advancing capabilities in pre-processing, computation, and post-processing. However, little attention has been paid to the support of the aforementioned iterative design process, which is the common practice in engineering design. Authors believe the next-generation CAE software should evolve into CAID (ComputerAided Iterative Design) software to help engineers go through the iterative design process and develop better engineering designs. In this paper, key software requirements for the iterative design process are discussed in this work. Furthermore, prototype CAID software developed using C, Qt, and VTK is demonstrated. The analyzing capability of the developed CAID software is based on an essential software framework for meshfree methods (ESFM). The proposed CAID concept and prototype software shall provide guidelines for future CAE software development.

Interpolation is an important operator in numerical methods for solving partial differential equations and in geospatial applications. There are many interpolation methods proposed in the past. In this work, a unified software framework is proposed through the use of design-patterns in object-oriented programming. By using this framework, little effort is necessary to implement different interpolations algorithms when commonality with implemented algorithms can be found. Furthermore, through this framework, it becomes easy to compare the performance of different algorithms because of the unified application interface..

Parametric studies in parallel-computing is often considered as an “embarrassingly parallel” computation task that can be trivially parallelized and yield good parallel efficiency. However, this paper shows the parallel efficiency of such analyses can be further improved by the proposed scheme in typical cluster setups using commodity PC hardware. Numerical experiments show that the parallel efficiency of such computation task in finite element analyses can be improved by 81.6% and the peak disk usage can be reduced by 83.1%. The proposed scheme for enhancing parallel performance can be readily extended to design optimization problems, which has similar work patterns in parallel processing. Therefore, more efficient engineering analyses and designs can be achieved by employing schemes described in this work.

Computational efficiency is of critical importance in the application of large-scale finite element simulations for solving complex geotechnical problems. This paper summarizes the formulation and implementation of a FETI domain decomposition technique for parallel finite element computations, highlighting the parallel efficiency and scalability of the software using a cluster of 16 interconnected commodity computers. The program is then used to simulate ground movements caused by the construction of a shallow cavern for a new subway station using a stacked-drift tunneling method which involved hand-excavation of a sequence of 15, 3m-square-section drifts through weathered alluvial soils. Figure 1 shows the cross-section of the cavern for the recently completed Rio Piedras station, part of the new Tren Urbano system in San Juan, Puerto Rico. The horseshoe-shaped cavern (17m wide, 16m high, and 150m long) was constructed in weathered alluvial soils. The crown of the cavern was located less than 5.5m below existing build- ings in a busy historic shopping district. Structural support for the cavern was provided by a series of 15 stacked drifts. These rectangular-section galleries (each typically 3m square) were excavated mainly by hand between two 30m deep access shafts and were then in-filled with concrete, while a primary compensation grouting system was designed to mitigate effects of excavation-induced ground movements on the overlying structures. Unexpectedly large settlements occurred during the early stages of drift construction and overwhelmed the original grouting sys- tem. As a result, an extensive consolidation grouting system was installed (to enable grouting closer to the tunnel heading). Despite these remedial measures, building settlements above the cavern at the end of construction ranged from 70mm to 130mm. In principle, non-linear finite element methods can be used to evaluate/predict the ground deformations caused by the stacked-drift construction. However, the complexity of the project presents a major challenge both in details of the modeling and in the scale of the computation. A comprehensive numerical model of the cavern would require detailed modeling of the unusual engineering properties and spatial variability of the weathered alluvium (Zhang et al. 2003), simulation of grout injections (and their effects on the surrounding soil), as well as the primary details of the drift excavation, lining and concrete infilling for each of the 15 drifts. The actual construction proce- dure involved concurrent excavation of between two and four drifts, Figure 1b (sometimes advancing in opposite directions), while concrete infilling took place from 3 to 60 days after excavation. Preliminary calculations found that very large 3-D finite element models (O(10 5 ) degrees of freedom) would be necessary to represent even these basic details of the stacked-drift construction. When non-linear soil behavior (with marginal face stability) was in- cluded in the finite element analyses, it soon became apparent that solutions using conventional direct equilibrium equation solvers or iterative (Krylov sub-space etc.) methods with single-processor machines would exceed practical limits on computational time and hence, a more efficient approach was required.

Publisher Summary There are many examples of transportation projects involving underground construction of shallow tunnels in soft ground conditions within congested urban environments. One of the key design criteria for such projects is to assess the impacts of the proposed tunnel construction methods (either by tunnel boring machines or by open-face excavation methods) on existing facilities and to control the construction procedures to limit deformations within the surrounding soil. Realistic modeling of these problems represents a very challenging problem that must typically simulate the following five conditions: (1) the complex sequence of excavation and support conditions at the advancing tunnel heading ; (2) the interaction between soil and the structural lining system; (3) the nonlinear behavior of the soil; (4) the coupled effects of groundwater seepage and deformations; and (5) ancillary activities ranging from grouting (either around the lining or within the soil mass) to soil nailing (reinforcement ahead of excavated face). Although many of these processes clearly require modeling in three dimensions, the great majority of analyses reported to date represent tunnel constructions using simplified plane strain models (using artificial concepts such as equivalent ground loss to represent 3D effects around the tunnel heading).