scholarly journals Long-Term Deformation Monitoring of Metro-Tunnel Airshaft Excavation during Construction Stage

2012 ◽  
Vol 8 (10) ◽  
pp. 972893 ◽  
Author(s):  
L. Ran ◽  
T. H. Yi ◽  
X. W. Ye ◽  
X. B. Dong
Keyword(s):  
Deformation Monitoring ◽  
Geological Condition ◽  
Building Structures ◽  
Construction Site ◽  
Construction Stage ◽  
Transit System ◽  
Depth Direction ◽  
Metro Tunnel ◽  
Metro Systems

The project of Hangzhou Metro Line 1 is the first metro line of the urban rapid rail transit system in Hangzhou, China, which is one of the largest municipal projects of Hangzhou and is being constructed commencing from March 28, 2007 and expected to be completed by October 1, 2012. This metro line has a total length of 48 km and 34 stations, connecting Hangzhou downtown with the suburban area of the city. Owing to the complex geological condition, harsh construction situation, and immature computational methodology, construction of metro systems is often subjected to considerable sources of uncertainties. To ensure the safety of the adjacent building structures, it is a vital necessity to monitor deep excavations of metro tunnels at their in-construction stage. This paper introduces the instrumentation system for settlement monitoring of a metro-tunnel airshaft of the project of Hangzhou Metro Line 1 during the construction of deep excavation. The long-term settlement data monitored by the measurement markers installed at the surface ground and in the depth direction of the airshaft excavation construction site are analyzed and presented in detail. The obtained results indicate that the settlements at the instrumented locations of the construction site during different construction steps vary steadily in an allowable variation range.

scholarly journals Most Frequent Problems of Building Structures of Urban Apartment Buildings from 2nd Half of 19th Century and the Start of 20th Century

Buildings ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 27
Author(s):  
Klara Kroftova
Keyword(s):  
20Th Century ◽  
19Th Century ◽  
Residential Building ◽  
Structural Safety ◽  
Horizontal Load ◽  
Building Structures ◽  
Speed Up ◽  
The 19Th Century ◽  
Basic Prerequisite

An urban residential building from the second half of the 19th century and the start of the 20th century, the so-called tenement house, is a significant representative of the architecture of the developing urban fabric in Central Europe. The vertical and horizontal load-bearing structures of these houses currently tend to show characteristic, repeated defects and failures. Their knowledge may, in many cases, facilitate and speed up the design of the historic building’s restoration without compromising its heritage value in this process. The article presents the summary of the most frequently occurring defects and failures of these buildings. The summary, however, is not an absolute one, and, in the case of major damage to the building, it still applies that, first of all, a detailed analysis of the causes and consequences of defects and failures must be made as a basic prerequisite for the reliability and long-term durability of the building’s restoration and rehabilitation. An integral part of the rehabilitation of buildings must be the elimination of the causes of the appearance of their failures and remediation of all defects impairing their structural safety, health safety and energy efficiency.

scholarly journals Long-Term Behavior of Coarse-Grained Rockfill Material and Their Constitutive Modeling

2021 ◽  
Author(s):  
Erich Bauer
Keyword(s):  
Mechanical Response ◽  
Coarse Grained ◽  
Geological Condition ◽  
Dam Foundation ◽  
Solid Hardness ◽  
Rockfill Materials ◽  
Materials Used ◽  
Creep And Stress Relaxation ◽  
Long Term Behavior

For the long-term behavior and safety assessment of rockfill dams, not only the shape of the dam body, the loading history, the geological condition of the dam foundation and abutments, the assessment of possible seismic hazards and seepage events caused by defects of the sealing are important, but also the time dependent mechanical behavior of the dam materials used can be of significant influence. In this paper a novel hypoplastic constitutive model for moisture sensitive, coarse-grained rockfill materials is presented. In the constitutive equations, the so-called solid hardness is a key parameter to reflect the influence of the state of weathering on the mechanical response. With respect to the evolution equation for the solid hardness, creep and stress relaxation can be modeled for dry and wet states of the material in a unified manner. The performance of the model is demonstrated by comparing the numerical simulation with experimental data.

Ensuring Safety at the Construction Site. Methodology of Static Testing of the Mineral Wool Joint for Punching between the Floor Slab and Building Facade during the Construction Stage

2021 ◽  
pp. 61-68
Author(s):  
V.A. Antonova ◽  
◽  
V.V. Vasilenko ◽  
G.D. Lelikov ◽  
N.V. Gromov ◽  
...  
Keyword(s):  
Concrete Slab ◽  
Test Methods ◽  
Performance Criterion ◽  
Mineral Wool ◽  
Potential Hazard ◽  
Construction Site ◽  
Construction Stage ◽  
Reinforced Concrete Slab ◽  
Static Testing ◽  
Object Of Study

The article presents the main provisions of ensuring safety on the construction site. Safety of the joint (at the construction stage) between the ceiling plate and the facade cladding sealed with the mineral wool (stone wool) and a firestop sealant is considered. A seam that has not yet been sealed presents a potential hazard of injury or falling objects to a lower level that requires actions within the standard procedures. When a seam is sealed, its hazard becomes less obvious. The purpose of this work is to assess the safety of the described design. For this purpose, a test setup, a method for testing a seal for static strength were developed, the tests were carried out with subsequent analysis and conclusions. The object of study is a seal (at the construction stage) between a reinforced concrete slab and a facade finishing element filled with a mineral wool and covered with a highly elastic refractory sealant. The testable criterion for the performance of the joint is its ability to withstand the load of a person. As a possible further continuation of this work, the first aspect that needs to be studied is the testing of a building element of a similar design during its operation phase, when the joint is covered with a reinforced screed with a thickness of 50 mm. The second important aspect is that the performance criterion should be extended to the fall of a rigid object from a height, and the appropriate tests should be carried out. The third important aspect is the need to develop test methods, in which the joint will be subjected to dynamic impact, since if the resistance of the joint to foot penetration or to objects falling from a height is considered, the load will not have a slow, static nature.

Contesting the greening of the urban growth machine: Ecological modernization and the promethean counter-discourse

2020 ◽  
pp. 251484862095232
Author(s):  
Emiliano Scanu ◽  
Geneviève Cloutier ◽  
Catherine Trudelle
Keyword(s):  
Urban Sprawl ◽  
Urban Growth ◽  
Environmental Governance ◽  
Ecological Modernization ◽  
Quebec City ◽  
Sustainable Mobility ◽  
Transit System ◽  
Growth Machine ◽  
Better Than

Urban environmental governance and planning are increasingly characterized by the adoption of “sustainability fixes,” namely political compromises which try to conciliate economic and ecological goals in order to safeguard long-term growth. If sustainability fixes have been harshly criticized for being sociospatially selective, resistance to them does not always come from radical groups who demand stronger and fairer measures, but from actors who oppose the idea of sustainability because it goes against their interests, habits, or values. This paper focuses on this “contestation of the greening of the urban growth machine,” by presenting an empirical study of a sustainable mobility policy in Quebec City, Canada, which has given rise to a controversy opposing two divergent perspectives. The first is an ecological modernization discourse advocating for a green and attractive public transit system. The second is a promethean counter-discourse which supports the unconditional growth of automobility and urban sprawl. Results show that even if urban environmental policies are increasingly attuned to the “growth first” logic, they could still face strong opposition, especially from suburban and conservative interests. More generally, this paper shows that, in some contexts, sustainability fixes could be a “better than nothing” solution, namely a step toward fairer and greener cities.

Assessing the Existing Bursa Light Rail Transportation System

2020 ◽  
Vol 2674 (10) ◽  
pp. 250-260
Author(s):  
Mehmet Rizelioğlu ◽  
Turan Arslan
Keyword(s):  
Traffic Congestion ◽  
Transportation System ◽  
Transportation Systems ◽  
Bus Rapid Transit ◽  
Light Rail ◽  
Rail Transportation ◽  
Transit System ◽  
Transit Systems ◽  
Negative Impacts

As car ownership soars, traffic congestion and its associated negative impacts have become real concerns in many cities around the world. Therefore, transportation systems that perform better in eliminating or reducing traffic congestion and related problems to tolerable levels have become imperative. Alternative transit systems should be assessed properly to accommodate the expected demand in the long term, at least, to some significant extent. However, this is generally neglected in developing countries and, among many possible alternatives, a popular transportation system is usually preferred within the available budget. As an example, Bursa Metropolitan Municipality, Turkey, has recently implemented a light rail transportation system (LRT) on its major east–west corridor as the main transit system. In this study, the existing LRT is assessed and its performance is compared with a hypothetical bus rapid transit (BRT) system, which is a strong contender and comparatively a lower-cost alternative. This is done to assess whether the LRT was the better choice in relation to the current demand. Therefore, in this study, the existing LRT system is first defined in the PTV VISSIM simulation environment. Then, the hypothetical BRT system is considered on the same route with the current demand. The capability and capacities of the existing LRT and the BRT system are assessed and compared in many aspects. The results are compared, and important findings are outlined.

Foot-mounted Pedestrian Navigation based on Particle Filter with an Adaptive Weight Updating Strategy

2014 ◽  
Vol 68 (1) ◽  
pp. 23-38 ◽  
Author(s):  
Yang Gu ◽  
Qian Song ◽  
Yanghuan Li ◽  
Ming Ma
Keyword(s):  
Particle Filter ◽  
A Priori ◽  
Close Relation ◽  
Building Structures ◽  
New Approach ◽  
Pedestrian Navigation ◽  
Regular Structures ◽  
Time Varying Parameter ◽  
Adaptive Weight

The algorithm flow of an inertial-based Pedestrian Navigation System (PNS) can be divided into a trajectory-generation stage and trajectory-calibration stage. The Zero-velocity UPdaTe (ZUPT)-aided Extended Kalman Filter (EKF) algorithm is commonly used to resolve the trajectory of a walking person, but it still suffers from long-term drift. Many methods have been developed to suppress these drifts and thus to calibrate the trajectory generated by the previous stage. However, these methods have certain requirements, such as explicit map information or frequent location revisits, which are hard to satisfy in such situations as Search and Rescue (SAR) operations. A new approach is proposed in this paper that requires no explicit presupposition. This approach is based on a particle filter framework, with the weight of particles being adaptively adjusted according to the a priori knowledge of building structures and human behaviours. The distribution of particle weights is designed with awareness of the regular structures of buildings. The time-varying parameter of the distribution is acquired from a Hidden Markov Model (HMM) based on the foregoing odometry, which has a close relation with human behaviour. HMM is trained offline based on samples acquired in advance. Many real-world experiments under various scenarios were performed, and the results indicate good accuracy and robustness of the proposed approach.

scholarly journals Fatigue Life Characteristics of Segmental Lining Structure for the Shallow Buried Metro Tunnel under the Dynamic Load of a High-Speed Railway

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Wangping Qian ◽  
Taiyue Qi ◽  
Qing Zhao ◽  
Bingrong Pu ◽  
Jin Zhang ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fatigue Failure ◽  
Dynamic Load ◽  
High Speed ◽  
Dynamic Loads ◽  
High Speed Railway ◽  
Segmental Lining ◽  
Lining Structure ◽  
Metro Tunnel

Shallow buried shield metro tunnels constructed underneath subgrade project of high-speed railways are becoming increasingly common in China, but the lower metro tunnel bears the fatigue effect of dynamic load induced by the upper high-speed railway, so the long-term durability of segmental lining is a nonnegligible problem. The segmental lining structure of metro tunnel is in a state of static-dynamic loads for a long time, especially when a high-speed railway passes above the metro line, and the long-term durability of segmental lining needs further research. Based on theoretical analysis, the effect of different forms of loads on the fatigue life was analyzed, the change law of the static-dynamic loads on segmental lining was summarized, and the method was put forward to evaluate the fatigue life characteristics of segmental lining. The research results reveal that the additional dynamic load is the fundamental reason for the fatigue failure of the structure, and the existence of static load can cause and accelerate the occurrence of structural fatigue failure simultaneously. The results indicate that the fatigue life decreases gradually with the increase of static-dynamic load. Based on coupling analysis of static-dynamic loads of segmental lining, the fatigue life increases first and then decreases with the increase of buried depth of metro tunnel, and it remains unchanged when the depth exceeds a certain value. According to the actual metro tunnel engineering, by using ABAQUS software, a three-dimensional numerical simulation was carried out to analyze the characteristics of the fatigue life and evolution rules of segmental lining. Based on the modified fatigue life formula and metro service life, the optimization design of the buried depth was carried out to determine the most reasonable range of the buried depth. This study provides a valuable reference for safe operation and long-term durability of metro tunnels under high-speed railways.

scholarly journals Deformation Monitoring and Stability Analysis of Shaft Lining in Weakly Cemented Stratum

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Xianzhou Lyu ◽  
Weiming Wang
Keyword(s):  
Real Time ◽  
Monitoring System ◽  
Coal Mine ◽  
Deformation Monitoring ◽  
Dynamic Monitoring ◽  
Thick Wall ◽  
Additional Stress ◽  
The Real ◽  
Shaft Lining

Shaft linings in thick weakly cemented stratum have the disadvantages of large deformation and repeated damage after repair. Considering the typical geologic characteristics and the failure characteristics of shaft linings, we establish a multilayer automatic deformation monitoring system in this paper, and the monitoring system can realize the real-time, continuous, and long-term dynamic monitoring on shaft linings. Based on the concrete strength failure criterion under biaxial compression and the analytical solution for spatially axisymmetric problem of thick-wall cylinders, the damage limit of the shaft lining in Xieqiao coal mine is obtained. Then, we choose three sections as the test area according to the typical damage forms of shaft linings to carry out the monitoring scheme on the auxiliary shaft in Xieqiao coal mine. The monitoring results show that the extreme value of the shaft lining deformation is 2.369 mm. And the shaft lining located in the border between the floor aquifer and the bedrock generates the most severe deformation, which is about 89.4% of the deformation limit. The shaft lining deformation increment fluctuates in certain range, which belongs to elastic deformation. Finally, we inverse the stress state according to the deformation value of the shaft lining, and the obtained additional stress is found to be lower than the ultimate compressive strength. Long-term project practice confirms that the deformation monitoring results can reflect the real stress condition of the shaft lining and that the monitoring system can realize the real-time dynamic evaluation for the status of the shaft lining.

scholarly journals Analyzing Near-Surface Regions of Hydrophobic and Long-Term Weathered Natural Stones at Microscopic Scale

Heritage ◽  
2020 ◽  
Vol 3 (2) ◽  
pp. 457-473
Author(s):  
Franziska Braun ◽  
Jeanette Orlowsky ◽  
Stefan Brüggerhoff
Keyword(s):  
Structural Changes ◽  
Color Difference ◽  
Outdoor Exposure ◽  
Material Surface ◽  
Building Structures ◽  
Near Surface ◽  
Visual Appearance ◽  
Microscopic Scale ◽  
Surface Damages

The visual appearance of building structures is an important attribute which reflects the character and identity of a region. Due to the influence of weathering, the surfaces of building stones alter, leading to aesthetic changes of the material surface such as discoloration or darkening. In this study, near-surface regions of weathered Baumberger (BST), Schleeriether (SST), and Obernkirchener Sandstones (OKS) have been analyzed at the microscopic scale in order to investigate the intensity and the extent of visual as well as structural changes and how both can be affected due to the presence of surface treatments with hydrophobing agents. It could be detected that aesthetic changes appeared already after 2 years of outdoor exposure, with the slightest variations on BST surfaces, followed by SST and OKS. The use of hydrophobing agents leads to a reduction in surface darkening in the short term. After long-term weathering, no significant changes are visible, as similar values in total color difference (ΔE*) were measured. Biogenic growth and the formation of black weathering crusts are the main reasons for color alterations in the case of the examined stones. The surface damages occur especially on calcareous (BST) followed by clayey (SST) and quartzitic (OKS) stone surfaces.

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