scholarly journals Role of Geologists During Tunnel Construction and Face Mapping to Decide the Required Tunnel Support

2021 ◽  
Vol 9 (9) ◽  
pp. 2080-2081
Author(s):  
Deepak Parkash Gupta
Keyword(s):  
Failure Modes ◽  
Design Stage ◽  
Underground Structures ◽  
Tunnel Support ◽  
Execution Phase ◽  
Geological Conditions ◽  
Ground Conditions ◽  
The Stability ◽  
Stress Behaviour

Abstract: The stability of underground structures is an important aspect during design, construction and execution Phase. Depending on the geotechnical conditions and influencing factors, different failure modes during execution mode can be expected, and depending on the potential failure modes, boundary conditions and specific construction measures to ensure stability have to be chosen. The most important is developing a realistic estimate of the expected ground conditions and their potential behaviour/failure modes as a result of the excavation. The variability of the geological conditions including local ground structure, ground parameters, stress and ground water conditions requires that a consistent and specific procedure is used. The other is to design an economic and safe excavation and support method for the determined ground behaviours. The discussion of role of geologists during design stage is beyond the scope of the present study. The main objective of this study is to present the role of geologists during the construction stage. Keywords: Geologist, Stress, Behaviour, RMR, Q Value, RQD, Rock Mass

scholarly journals A Study of the Effects of Geological Conditions on Korean Tunnel Construction Time Using the Updated NTNU Drill and Blast Prediction Model

2021 ◽  
Vol 11 (21) ◽  
pp. 10096
Author(s):  
Yangkyun Kim ◽  
Sean Seungwon Lee
Keyword(s):  
Rock Mass ◽  
Prediction Model ◽  
Rock Properties ◽  
Design Stage ◽  
Construction Time ◽  
Tunnel Support ◽  
Advance Rate ◽  
Rock Mass Quality ◽  
Geological Conditions ◽  
Drill And Blast

This paper analyses the construction time and advance rate of a 3 km long drill and blast tunnel under various geological conditions using an upgraded NTNU drill and blast prediction model. The analysis was carried out for the five types of Korean tunnel supports according to the rock mass quality (from Type 1, meaning a very good rock mass quality; to Type 5, meaning a very poor rock mass quality). Four kinds of rock properties, as well as the rock mass quality, for each tunnel support type were applied to simulate different geological conditions based on previous studies and the NTNU model. The construction time was classified into five categories: basic, standard, gross, tunnel and total, according to the operation characteristics to more effectively analyse the time. In addition, to consider the actual geological conditions in tunnelling, the construction times for the three mixed geological cases were analysed. It was found that total construction time of a tunnel covering all the operations and site preparations with a very poor rock mass quality was more than twice that of a tunnel with a very good rock mass quality for the same tunnel length. It is thought that this study can be a useful approach to estimating the construction time and advance rate in the planning or design stage of a drill and blast tunnel.

scholarly journals Evaluation of earth pressure on buried pipes and stability of surroundings according to construction condition

2015 ◽  
Vol 18 (1) ◽  
pp. 64-72
Author(s):  
Son Truong Bui
Keyword(s):  
Limit State ◽  
Earth Pressure ◽  
Underground Water ◽  
Actual Condition ◽  
Underground Structures ◽  
Buried Pipes ◽  
The Earth ◽  
Geological Conditions ◽  
The Stability ◽  
Construction Condition

Earth pressure on buried pipes structure depends not only on soil type, shape and dimension of structure but also on depth, shape and dimension of excavated holes and other factors such as structure load, underground water level. Based on the selected and modified computational scheme with self-established program, the earth pressure on pipe structures according to the construction condition is evaluated and analysed. It is recommended to choose the buried depth for structure in “cut and cover” excavation method so that the influence of earth pressure is reasonably steady from the buried point downward. The replacement of backfill material to cohesive material partially can help to reduce significantly the earth pressure on the buried structure. In addition, evaluation of the the degree of approaching to limit state in surroundings in bored tunnelling excavation allows for analysing the stability in various geological conditions according to the appearance of plastic zone. The research results are useful for calculating and arranging underground structures reasonably in actual condition

scholarly journals Ground subsidence due to the backfill pressure in tunnel boring machine

2020 ◽  
Vol 382 ◽  
pp. 19-24
Author(s):  
Chang-Kyun Ahn ◽  
Seok-Won Lee
Keyword(s):  
Ground Cover ◽  
Tunnel Boring Machine ◽  
Ground Subsidence ◽  
Design Stage ◽  
Shield Tunnel ◽  
Underground Structures ◽  
Tunnel Boring ◽  
Backfill Pressure ◽  
Ground Conditions ◽  
The Impact

Abstract. In shield tunnel boring machine constructions, backfill pressure affects surface settlement and the stability of other underground structures nearby. Therefore, it is essential to pre-calculate backfill pressure in the design stage. This study examines and compares the seven internationally known backfill pressure calculation theories and calculates and analyzes the backfill pressures in six virtual ground conditions. The calculated backfill pressure increased as the ground cover increased, but the increase rate decreased. Also, this study performs a numerical analysis to identify the impact on ground settlement and tunnel crown settlement. In the end, settlement was more impacted by face pressure than backfill pressure in the unsaturated and saturated ground conditions. Also, as the ground cover increased, the impact of backfill pressure decreased, and as the applied face pressure decreased, the impact of backfill pressure increased.

Local Buckling Analysis for Large Diameter Underground Jacked Steel Tubes under External Load

2010 ◽  
Vol 452-453 ◽  
pp. 501-504
Author(s):  
Chun Fu Jin ◽  
Shi Yan ◽  
Peng Niu
Keyword(s):  
Failure Modes ◽  
Large Diameter ◽  
Local Buckling ◽  
Steel Tube ◽  
Buckling Analysis ◽  
Underground Structures ◽  
Nonlinear Buckling ◽  
Practical Engineering ◽  
The Stability ◽  
Nonlinear Buckling Analysis

Densely arranged underground steel tube system (DAUSTS) is a new kind of structure which can be usually used in constructing spacious underground structures such as metro stations. During the construction, the steel tube is horizontally forced into soil by jacks through a vertical well. The tube may generate local buckling phenomena under the compression force if the parameter of the tube and soil meet the buckling condition. In the paper, the soil perturbation mode and the deformation of the tube before local buckling are both analyzed, considering the possibly concerned buckling failure modes in practical engineering, the confine effect of the soil and interaction between the tubes. A nonlinear buckling analysis on tube-wall of the steel tube located in the most unfavorable place is developed by the arc-length method of the finite element method (FEM), considering the effect of the large deformation. The results of the numerical simulation matches very well to the real application and the key results of the analysis can be used as an estimation principle for the stability of the tube.

A Statistical Study of Process Variables to Optimize a High Speed Curtain Coater: Part I

TAPPI Journal ◽  
2009 ◽  
Vol 8 (1) ◽  
pp. 20-26 ◽  
Author(s):  
PEEYUSH TRIPATHI ◽  
MARGARET JOYCE ◽  
PAUL D. FLEMING ◽  
MASAHIRO SUGIHARA
Keyword(s):  
Boundary Layer ◽  
Experimental Design ◽  
High Speed ◽  
Statistical Study ◽  
Process Variables ◽  
High Speeds ◽  
The Stability ◽  
Air Removal ◽  
Removal System

Using an experimental design approach, researchers altered process parameters and material prop-erties to stabilize the curtain of a pilot curtain coater at high speeds. Part I of this paper identifies the four significant variables that influence curtain stability. The boundary layer air removal system was critical to the stability of the curtain and base sheet roughness was found to be very important. A shear thinning coating rheology and higher curtain heights improved the curtain stability at high speeds. The sizing of the base sheet affected coverage and cur-tain stability because of its effect on base sheet wettability. The role of surfactant was inconclusive. Part II of this paper will report on further optimization of curtain stability with these four variables using a D-optimal partial-facto-rial design.

The Role of Hydrophobicity in the Stability and pH-Switchability of (RXDX)4 and Coumarin-RXDX Conjugate β-Sheets

2020 ◽  
Author(s):  
Ryan Weber ◽  
Martin McCullagh
Keyword(s):  
Biological Imaging ◽  
Ph Sensing ◽  
Hydrophobic Residue ◽  
Ideal Candidate ◽  
Self Assembling ◽  
Sensing Applications ◽  
Β Sheets ◽  
The Stability ◽  
Dynamics Simulations

<p>pH-switchable, self-assembling materials are of interest in biological imaging and sensing applications. Here we propose that combining the pH-switchability of RXDX (X=Ala, Val, Leu, Ile, Phe) peptides and the optical properties of coumarin creates an ideal candidate for these materials. This suggestion is tested with a thorough set of all-atom molecular dynamics simulations. We first investigate the dependence of pH-switchabiliy on the identity of the hydrophobic residue, X, in the bare (RXDX)<sub>4</sub> systems. Increasing the hydrophobicity stabilizes the fiber which, in turn, reduces the pH-switchabilty of the system. This behavior is found to be somewhat transferable to systems in which a single hydrophobic residue is replaced with a coumarin containing amino acid. In this case, conjugates with X=Ala are found to be unstable and both pHs while conjugates with X=Val, Leu, Ile and Phe are found to form stable β-sheets at least at neutral pH. The (RFDF)<sub>4</sub>-coumarin conjugate is found to have the largest relative entropy value of 0.884 +/- 0.001 between neutral and acidic coumarin ordering distributions. Thus, we posit that coumarin-(RFDF)<sub>4</sub> containing peptide sequences are ideal candidates for pH-sensing bioelectronic materials.</p>

Metal-Metal Cooperative Bond Activation by Heterobimetallic Alkyl, Aryl, and Acetylide PtII/CuI Complexes

2020 ◽  
Author(s):  
Shubham Deolka ◽  
Orestes Rivada Wheelaghan ◽  
Sandra Aristizábal ◽  
Robert Fayzullin ◽  
Shrinwantu Pal ◽  
...  
Keyword(s):  
Alkyl Group ◽  
Bond Activation ◽  
Bond Cleavage ◽  
Terminal Alkyne ◽  
Alkyl Aryl ◽  
Metal Metal ◽  
The Stability ◽  
Selective Formation ◽  
Organoplatinum Compounds

We report selective formation of heterobimetallic PtII/CuI complexes that demonstrate how facile bond activation processes can be achieved by altering reactivity of common organoplatinum compounds through their interaction with another metal center. The interaction of the Cu center with Pt center and with a Pt-bound alkyl group increases the stability of PtMe2 towards undesired rollover cyclometalation. The presence of the CuI center also enables facile transmetalation from electron-deficient tetraarylborate [B(ArF)4]- anion and mild C-H bond cleavage of a terminal alkyne, which was not observed in the absence of an electrophilic Cu center. The DFT study indicates that the role of Cu center acts as a binding site for alkyne substrate, while activating its terminal C-H bond.

LANDSLIDE RISK MANAGEMENT IN THE COASTAL ZONE OF THE KUIBYSHEV RESERVOIR DUE THE DESIGN OF HIGH-SPEED LINE "MOSCOW-KAZAN"

2017 ◽  
Author(s):  
Nikolai Petrov ◽  
Nikolai Petrov ◽  
Inna Nikonorova ◽  
Inna Nikonorova ◽  
Vladimir Mashin ◽  
...  
Keyword(s):  
High Speed ◽  
Computational Models ◽  
Stable State ◽  
Landslide Risk ◽  
Kuibyshev Reservoir ◽  
Stepped Surface ◽  
The Stability ◽  
Landslide Slope ◽  
The Village

High-speed railway "Moscow-Kazan" by the draft crosses the Volga (Kuibyshev reservoir) in Chuvashia region 500 m below the village of New Kushnikovo. The crossing plot is a right-bank landslide slope with a stepped surface. Its height is 80 m; the slope steepness -15-16o. The authors should assess the risk of landslides and recommend anti-landslide measures to ensure the safety of the future bridge. For this landslide factors have been analyzed, slope stability assessment has been performed and recommendations have been suggested. The role of the following factors have been analyzed: 1) hydrologic - erosion and abrasion reservoir and runoff role; 2) lithologyc (the presence of Urzhum and Northern Dvina horizons of plastically deformable rocks, displacement areas); 3) hydrogeological (the role of perched, ground and interstratal water); 4) geomorphological (presence of the elemental composition of sliding systems and their structure in the relief); 5) exogeodynamic (cycles and stages of landslide systems development, mechanisms and relationship between landslide tiers of different generations and blocks contained in tiers). As a result 6-7 computational models at each of the three engineering-geological sections were made. The stability was evaluated by the method “of the leaning slope”. It is proved that the slope is in a very stable state and requires the following measures: 1) unloading (truncation) of active heads blocks of landslide tiers) and the edge of the plateau, 2) regulation of the surface and groundwater flow, 3) concrete dam, if necessary.

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