scholarly journals Effects of Excavation Gap Filling of Under-1 Crossing Tunnel on Pipelines

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Hua Jiang ◽  
Longfei Chang ◽  
Jingling Zhang ◽  
Pinglin Jiang
Keyword(s):  
Soil Layer ◽  
Field Tests ◽  
Vertical Displacement ◽  
Development Trend ◽  
Surface Settlement ◽  
Shield Tunnel ◽  
Future Research ◽  
Gap Filling ◽  
Strata Movement ◽  
Geological Conditions

Excavation gap filling is an important means to control the strata movement in tunneling. In practice, synchronous grouting or secondary replenishment of the gap is usually used to control the settlement, instead of filling the excavation clearance. In fact, the diameter of the cutterhead is usually slightly larger than that of the shield, and the front shield is also larger than its back. As a result, there will be an annular gap (i.e., an excavation clearance) between the tunnel soil layer and the shield. Thus, effectively filling the gap contributes to controlling the formation displacement. In this paper, the Wei Lai Da Dao to Feng Tai Nan Lu section of Zhengzhou Metro Line 3 is selected as the study object. Based on the three-dimensional finite element method, the influence of an under-crossing shield tunnel sewage pipes on strata movement under complicated conditions is analyzed. Field tests also show that the movement and development trend are similar to the simulated results, which further indicates that, under similar geological conditions, numerical simulation results can be used to guide the filling of excavation clearance in EPB. It is found that the excavation gap filling can effectively reduce the surface settlement rate and make the surface settlement stabilize faster and the curve shape of “settlement trough” changes from “narrow and deep” to “shallow and wide.” However, the grout used in this method should be with the properties of short hardening time, large elastic modulus, and low shear strength. Besides, the excavation gap filling can also reduce the extrusion deformation of sewage pipe and inhibit the horizontal and vertical displacement of sewage pipes. Therefore, it is considered that excavation clearance filling is an effective method to reduce stratum movement and tunnel deformation, which is of great significance for future research and practical engineering.

Three Dimensional Numerical Analysis of Ground Settlement Induced by Shield Tunneling

2012 ◽  
Vol 182-183 ◽  
pp. 937-940
Author(s):  
Zhong Chang Wang
Keyword(s):  
Soil Layer ◽  
Three Dimensional ◽  
Ground Surface ◽  
Vertical Displacement ◽  
Ground Subsidence ◽  
Shield Tunnel ◽  
Ground Settlement ◽  
Shield Tunneling ◽  
Tunnel Face ◽  
Maximum Settlement

The fine numerical simulation is used to study the ground settlement of complex stratum owing to shield construction by ANSYS program. It is shown that the closer the distance between soil layer and the axis of tunnel is, the smaller the disturbance of construction is, the obvious the ground surface settlement is. The value of the maximum settlement at the center of the surface is 7.4mm. The maximum settlement of vault is 14mm. The ground subsidence in cross section distribution is shaped of normal distribution. The closer the distance between soil layer and ground surface is, the smaller the vertical displacement is, the bigger the width of settlement trough of soil layers is. The width of settlement trough is 25m. The volume loss rate of shield tunnel is about 0.32%. The width coefficient of ground settlement trough is 0.56. The tendency of ground settlement decrease to become gentle with the advance of shield construction. The ground settlement keeps constant after tunnel face advancing to 30m.

scholarly journals Numerical Study on the Disturbance Effect of Short-Distance Parallel Shield Tunnelling Undercrossing Existing Tunnels

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Zhen Huang ◽  
Chenlong Zhang ◽  
Helin Fu ◽  
Huangshi Deng ◽  
Shaokun Ma ◽  
...  
Keyword(s):  
Numerical Model ◽  
Short Distance ◽  
Maximum Stress ◽  
Numerical Study ◽  
Soil Layer ◽  
Field Monitoring ◽  
Surface Settlement ◽  
Shield Tunnel ◽  
Double Line ◽  
Shield Tunnelling

The construction of new tunnels poses a threat to the operational safety of closely existing tunnels, and the construction mode of parallel undercrossing over short distances has the most significant impact. In this study, a new double-line shield tunnel parallel undercrossing of existing tunnels in Hefei, China, is taken as an example. A three-dimensional (3D) numerical model using FLAC3D finite difference software was established. The dynamic construction of the new double-line shield tunnel undercrossing the existing subway tunnel over a short distance and in parallel was simulated. The pattern of existing tunnel settlement and change in lining stress caused by the shield tunnelling process were analyzed. The reliability of simulation was verified through field-monitoring data. Finally, based on the numerical model, the effects of change in stratum sensitivity on the settlement of existing tunnel, lining internal force, and surface settlement are discussed. The results show that during shield tunnelling, the maximum ground settlement is 3.9 mm, the maximum settlement at the arch waist of existing tunnel near the new tunnel is 7.75 mm, and the maximum vault settlement is 5.38 mm. The maximum stress of lining of existing tunnel before the excavation is 7.798 × 105 Pa. After the construction of double-line shield tunnel, the maximum stress of lining is 1.124 × 106 Pa, an increase of 44% than that before the construction. The surface settlement and tunnel settlement are sensitive to the weakening of soil layer strength, and lining stress is not affected by the weakening of soil layer strength. The field-monitoring results are consistent with the numerical simulation results, and the model calculation is reliable. This study plays an important role in ensuring construction safety and optimizing the construction risk control of a tunnel.

Cryogels as a solution to the issues of environmental management and trunk pipeline operation in Arctic

2020 ◽  
Vol 10 (2) ◽  
pp. 173-185
Author(s):  
Lyubov K. Altunina ◽  
◽  
Vladimir P. Burkov ◽  
Petr V. Burkov ◽  
Vitaly Y. Dudnikov ◽  
...  
Keyword(s):  
Composite Materials ◽  
Field Experiments ◽  
Oil And Gas ◽  
Soil Layer ◽  
Soil Microflora ◽  
Russian Arctic ◽  
Thaw Cycle ◽  
Trunk Pipeline ◽  
Geological Conditions ◽  
Spatial Lattice

In the Russian Arctic, a soil cryostructuring technique (i.e. strengthening of soil horizons with cryogel-based composite materials with no excavation of unstable soils required) seems to be showing promise. Experiments have proven that mechanical and thermal insulation properties attributed to cryogels make them appropriate for use in strengthening and thermally insulating the soil, while their structure makes it possible to form a stable vegetation cover. Field experiments have confirmed that cryostructuring efficiently strengthens the soil layer with cryogels stimulating soil microflora. An experience of using cryotropic compositions in the oil and gas sector was described. Notably, cryogels can be used to strengthen unstable soil foundations of trunk pipelines, as well as to bind soil (e.g. on slopes). In addition, cryogels are advised for use in engineering protection to prevent the uneven settlement of a trench base and its creep: thus, cryogels are pumped into the soil of the trench bottom base to create a support system representing a spatial lattice. After the first freeze and thaw cycle, cryotropic material is formed and then increases its strength and elasticity with each new cycle. More broadly, opportunities have been considered regarding cryogels used in various engineering and geological conditions, while taking into account the outcomes of landscape and territorial analysis. It was concluded that cryogel-based composite materials are a promising innovative scientific field expanding technological capabilities for developing and using spaces and resources in the Russian Arctic.

Review of Research on Hydrostatic Bearings

2020 ◽  
Vol 13 ◽  
Author(s):  
Xiaodong Yu ◽  
Yu Wang ◽  
Junfeng Wang ◽  
Wenkai Zhou ◽  
Hongwei Bi ◽  
...  
Keyword(s):  
High Speed ◽  
Static Pressure ◽  
Development Trend ◽  
Cnc Machining ◽  
Pressure Effects ◽  
Cnc Machine Tools ◽  
Future Research ◽  
Theoretical Formula ◽  
Hydrostatic Bearing ◽  
Hydrostatic Bearings

Background: Hydrostatic bearings have the advantages of strong bearing capacity, good stability, small friction coefficient and long life. The performance of liquid hydrostatic bearings directly affect the accuracy and efficiency of CNC machining equipment. The performance is conducive to the development of CNC machine tools towards high speed and heavy load, so it is necessary to sort out and summarize the existing research results. Objective: This study summarizes the current development status of hydrostatic bearings and explains the development trend of hydrostatic bearings. Methods: According to the recently published journal articles and patents, the recent experimental research on hydrostatic thrust bearings is summarized. This paper summarizes many factors that affect the performance of hydrostatic bearings, and discusses the causes of various factors on hydrostatic bearings. Finally, future research on hydrostatic bearings is presented. Results: The study discusses experimental methods, simulation processes, and experimental results. Conclusion: This study can produce dynamic and static pressure effects by changing the structure of the oil cavity of the hydrostatic bearing. This effect can make up for the static pressure loss. By improving the theoretical formula and mathematical model and proposing a new simulation method, the accuracy of the hydrostatic bearing simulation is satisfied; the future development trend of the hydrostatic bearing is proposed.

scholarly journals Research on the Literature of Green Building Based on the Web of Science: A Scientometric Analysis in CiteSpace (2002–2018)

2019 ◽  
Vol 11 (13) ◽  
pp. 3716 ◽  
Author(s):  
Yingling Shi ◽  
Xinping Liu
Keyword(s):  
Web Of Science ◽  
Green Building ◽  
Development Trend ◽  
Status Quo ◽  
Future Research ◽  
Building Industry ◽  
Scientometric Analysis ◽  
The Past ◽  
Evolution Pattern ◽  
The Status

Since the 21st century, the concept of green building has been gradually popularized and implemented in more countries, which has become a popular direction in the area of sustainability in the building industry. Over the past few decades, many scholars and experts have done extensive research on green building. The purpose of this paper is to systematically analyze and visualize the status quo of green building. Therefore, based on Web of Science (WoS), this paper analyzed the existing knowledge system of green building using CiteSpace, identified keywords related to green building and their frequency of occurrence using the function of keyword co-occurrence analysis, recognized five clusters using the function of cluster analysis, and explored the knowledge evolution pattern of green building using citation bursts analysis in order to reveal how research related to green building has evolved over time. On the basis of aforementioned keywords, clusters, and citation bursts analysis, this paper has built a knowledge graph for green building. This paper can help readers to better understand the status quo and development trend of green building and to easier recognize the shortcomings in the development of green building, so as to provide a promising direction for future research.

Recent Reviews on Machine Vision-Based 3D Reconstruction

2021 ◽  
Vol 14 ◽  
Author(s):  
Hongxin Zhang ◽  
Shaowei Ma ◽  
Meng Li ◽  
Hanghang Jiang ◽  
Jiaming Li
Keyword(s):  
Machine Vision ◽  
3D Reconstruction ◽  
Autonomous Navigation ◽  
Robot Vision ◽  
Research Direction ◽  
Development Trend ◽  
Future Research ◽  
The Future ◽  
The Development Trend ◽  
Better Than

Background: In machine vision, the 3D reconstruction is widely used in medical system, autonomous navigation, aviation and remote sensing measurement, industrial automation and other fields, and the demand for reconstruction precision is significantly highlighted. Therefore, the 3D reconstruction is of great research value and will be an important research direction in the future. Objective: By reviewing the latest development and patent of 3D reconstruction, this paper provides references to researchers in related fields. Methods: Machine vision-based 3D reconstruction patents and literatures were analyzed from the aspects of the algorithm, innovation and application. Among them, there are more than 30 patents and nearly 30 literatures in the past ten years. Results: Researches on machine vision-based 3D reconstruction in recent 10 years are reviewed, and the typical characteristics were concluded. The main problems in its development were analyzed, the development trend was foreseen, and the current and future research on the productions and patents related to machine vision-based 3D reconstruction is discussed. Conclusion: The reconstruction result of binocular vision and multi-vision is better than monocular vision in most cases. Current researches of 3D reconstruction focus on robot vision navigation, intelligent vehicle environment sensing system and virtual reality. The aspects that need to be improved in the future include: improving robustness, reducing computational complexity, and reducing operating equipment requirements, and so on. Furthermore, more patents on machine vision-based 3D reconstruction also should be invented.

Construction Techniques of Deep Diaphragm Wall in the Yellow River-Crossing Project in South-to-North Water Transfer

2011 ◽  
Vol 250-253 ◽  
pp. 1212-1216
Author(s):  
Da Hu Rui ◽  
Qing Hong Wu ◽  
Zhen Feng Cao ◽  
Yu Xia Zhao ◽  
Guang Fan Li
Keyword(s):  
Yellow River ◽  
Water Transfer ◽  
Diaphragm Wall ◽  
Shield Tunnel ◽  
Medium Sand ◽  
Construction Techniques ◽  
Geological Conditions ◽  
North Bank ◽  
Guide Wall ◽  
North Water

Yellow River-Crossing Project in South-to-North Water Transfer approach through the use of shield tunnel and its north bank departure shaft adopts diaphragm wall as enclosure structure. The depth of continuous wall of its shielding starting shaft is 76.6m, which is the deepest at present in china. The continuous diaphragm wall travels through the layer of silver sand, medium sand and loam from top to bottom, where the geological conditions are poor with large difficulty of construction. This paper sets forth construction of guide wall, reinforcing measures before construction, Trenching process, groove segment connections, innovative technologies of uplifting huge reinforcing cage and so on, which will provide guidance and lessons for the similar project

scholarly journals Experimental study on dynamic response of model shield tunnel induced by moving-axle loads of subway train

2018 ◽  
Vol 14 (10) ◽  
pp. 155014771880278
Author(s):  
Mengxi Zhang ◽  
Xiaoqing Zhang ◽  
Lei Li ◽  
Chengyu Hong
Keyword(s):  
Time History ◽  
Vertical Displacement ◽  
Wheel Speed ◽  
Dynamic Responses ◽  
Scale Model ◽  
Shield Tunnel ◽  
Laboratory Model ◽  
Cover Depth ◽  
Axle Loads ◽  
Subway Train

A new testing method was introduced to apply moving-axle loads of a subway train on a track structure. In order to investigate the dynamic responses of the shield tunnel subjected to moving-axle loads, a series of laboratory model tests were conducted in a 1/40 scale model tunnel. The influences of the axle load, the wheel speed, and the cover depth of the shield tunnel on the vertical displacement and acceleration of the lining were presented and discussed. Parametric studies revealed that the vertical displacement–time history of the lining presents a “W” shape due to the combined action of two axles of a bogie. The peak value of the vertical displacement increased with the axle load linearly, while it decreased with the increase in the cover depth. Moreover, response time of the displacement decreased with the increase in the wheel speed, but the peak values remained stable at the same level. Finally, a three-dimensional dynamic finite element model was adopted to simulate the movement of the axle loads and calculate the responses of the lining. The numerical results analysis agrees well with experimental results.

Identifying Cable Tension Loss and Deck Damage in a Cable-Stayed Bridge Using a Moving Vehicle

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Shih-Hsun Yin ◽  
Chung-Yu Tang
Keyword(s):  
Computational Study ◽  
Vertical Displacement ◽  
Relative Displacement ◽  
Future Research ◽  
Integration Scheme ◽  
Time Step ◽  
Cable Tension ◽  
Displacement Response ◽  
Cable Stayed Bridge ◽  
Response Vector

This paper presents a computational study on a new method of detecting multiple simultaneous damages in a cable-stayed bridge by use of the analysis of the vertical dynamic response of a vehicle passing the bridge. First, the study uses a finite-element method to simulate the vehicle cable-stayed bridge system. Then, the vertical vibration interaction between the bridge and the vehicle is solved by a time-step integration scheme. In this research, we consider that two kinds of damage including cable tension loss and deck damage may occur simultaneously at different locations. The differences between the vertical displacement responses of a vehicle passing the damaged bridge and the healthy bridge are sampled and called the relative displacement response vector of the vehicle. The proper orthogonal decomposition (POD) is utilized to decompose the relative displacement response vector of the vehicle passing the bridge with unknown multiple damages into an optimal set of basis vectors formed from the ones of the vehicle moving over the known damaged bridges. The associated system parameters variation with the unknown multiple damages can be reconstructed further. Discussions are given concerning the feasibility and limitation of the proposed detection technique as well as directions for future research.

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