Tunnelling in Brasília porous clay

1996 ◽  
Vol 33 (4) ◽  
pp. 565-573 ◽  
Author(s):  
J AR Ortigao ◽  
R Kochen ◽  
M M Farias ◽  
A P Assis
Keyword(s):  
Field Measurements ◽  
Residual Soils ◽  
Tunnel Face ◽  
Tunnel Design ◽  
Tunnel Diameter ◽  
Underground Transportation ◽  
Surface Settlements ◽  
Horizontal Displacements ◽  
Design Construction

The Brasília underground transportation system comprises 6.5 km of shallow tunnel excavated in a soft red soil known as porous clay that overlies harder residual soils. The tunnel diameter is 9.6 m. Settlement observations indicated that surface settlements were two to three fold the initially predicted value, although no indication of excavation instability was observed. Settlements reached, at one section, 500 mm without failure. Another striking feature was settlement amplification between the top of the excavation and the surface by a factor that averaged 1.2 but reached up to 4. This occured because of the collapsible nature of the porous clay, which presented a considerable reduction of volume as the tunnel face advanced. This paper describes tunnel design, construction, and instrumentation; and summarizes geology and soil properties from in situ and laboratory tests. Field measurements of settlements and horizontal displacements are described and analysed. The main cause of the large settlements was collapse of the porous clay structure. Key words: tunnelling, porous clay, settlements, collapse.

Horizontal displacements induced by rock excavation: Scotia Plaza, Toronto, Ontario

1989 ◽  
Vol 26 (1) ◽  
pp. 114-121 ◽  
Author(s):  
W. A. Trow ◽  
K. Y. Lo
Keyword(s):  
Field Measurements ◽  
Horizontal Displacement ◽  
Time Dependent ◽  
Rock Excavation ◽  
Initial State ◽  
Deformation Parameters ◽  
Adjacent Structures ◽  
Rock Anchors ◽  
Horizontal Displacements

The design and construction of a 69-storey building, the Scotia Plaza in downtown Toronto, Ontario, necessitated an assessment of the horizontal displacements induced onto adjacent existing structures as a result of rock excavation. Field and laboratory tests were performed to measure the elastic and time-dependent deformation parameters as well as the in situ horizontal stresses in rock. With the deformation parameters and initial state of stresses determined, analyses were performed to predict the magnitude and distribution of elastic and time-dependent deformation. During excavation, horizontal displacements were monitored by (a) a field slot test to verify the rock mass modulus, (b) inclinometers and extensometers, and (c) internal taping of floors of adjacent structures. The results of these field measurements are compared with those predicted in the design analysis, and are found to be within the predicted limits and design requirements. The use of rock anchors to partially suppress time-dependent displacements is also briefly discussed. Key words: rock excavation, horizontal displacement, time-dependent deformation, in situ stresses, rock anchors.

scholarly journals APPLICATION OF ELECTRIC EXPLORATION AND ATMOGEOCHEMICAL TECHNOLOGIES IN SEISMIC MICROZONING OF A TUNNEL JUNCTION THROUGH THE MARKOTKH RIDGE

2020 ◽  
Vol 12 (4) ◽  
pp. 542-554
Author(s):  
Nikolay FOMENKO ◽  
◽  
Natalia BOROVIK ◽  
Dmitriy GAPONOV ◽  
Ludmila FOMENKO ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Electric Field ◽  
Field Measurements ◽  
Field Studies ◽  
Crossing Over ◽  
Geophysical Research ◽  
Seismic Microzoning ◽  
Tunnel Design ◽  
The Right ◽  
Design Construction

Aim. Investigation of the electrical exploration effectiveness and atmogeochemical technologies for detecting discontinuous and folded tectonic disturbances during seismic microzoning of the tunnel crossing over the "Markotkhsky ridge" Task. Study of the tectonic disturbance degree and flooding of the flysch strata using spatial electrical filtration, electropotential tomographic sensing, and atmogeochemical measurements along the tunnel route using data from route surveys and drilling at the tunnel design site. Research methods. 1) Field electrical survey measurements of spatial electrical filtration and electropotential tomographic sensing and with installations of multidirectional electric field excitation for" highlighting " target objects. 2) Using a multi-variant system for presenting field data in the form of tomograms and in the form of electro-profiling and sounding to identify destructive zones related to tectonically disturbed rocks and flood zones. Research results. The analysis of domestic and foreign publications on the use of electrical exploration methods in seismic microdistricting of design, construction and operation of critical facilities is performed. On the example of a tunnel crossing over the Markotkhski ridge: 1) geological, geo-ecological, and seismological characteristics of the area of engineering and geophysical research are considered; 2) the field studies of spatial technologies electric filtrazione, electropotentials tomographic probing and atmogeochemical of observations are produced; 3) the heterogeneity of fliteway thickness laterally and quasioperational this thickness on the electrical properties at depth is shown; 4) as a result poperechnogo analysis curves electropotentials tomographic probing, as well as charts of the spatial electric filtrational and atmogeochemical measurements of an tectonically disturbed and watery areas are identified; 5) the degree of differentiation of the flysch thickness by the values of the specific electrical resistance was estimated using a pseudo-section constructed in the Res2Dinv program. Conclusions. The technologies of electropotential tomographic sounding and spatial electric filtration are unique in terms of mobility and simplicity of field measurements, subsequent geological and geophysical interpretation of anomalous values of the electric field based on its redistribution in tectonically and technogenically disturbed geological structures. The result is the identification of places of development of tectonic discontinuities and watered zones, information about which makes it possible to predict, along with the seismicity of the rock mass inside the tunnel, possible places of potential collapse and flooding during the design, construction and subsequent operation of tunnel crossings. A significant achievement of the experiments can be attributed to the identification of the possibility of electroprobing the flysch strata with steeply-and obliquely-lying layers by dipole electric exploration installations. The proof is that the growth of the right branches of the probing curves does not exceed 45°. Consequently, the steeply-and obliquely-lying flysch strata can be considered heterogeneous laterally and quasihomogeneous in depth in terms of electrical properties.

scholarly journals Underwater Holographic Sensor for Plankton Studies In Situ Including Accompanying Measurements

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4863
Author(s):  
Victor Dyomin ◽  
Alexandra Davydova ◽  
Igor Polovtsev ◽  
Alexey Olshukov ◽  
Nikolay Kirillov ◽  
...  
Keyword(s):  
World Ocean ◽  
Field Tests ◽  
Field Measurements ◽  
Measuring Systems ◽  
Water Turbidity ◽  
Background Data ◽  
Average Size ◽  
Size Dispersion

The paper presents an underwater holographic sensor to study marine particles—a miniDHC digital holographic camera, which may be used as part of a hydrobiological probe for accompanying (background) measurements. The results of field measurements of plankton are given and interpreted, their verification is performed. Errors of measurements and classification of plankton particles are estimated. MiniDHC allows measurement of the following set of background data, which is confirmed by field tests: plankton concentration, average size and size dispersion of individuals, particle size distribution, including on major taxa, as well as water turbidity and suspension statistics. Version of constructing measuring systems based on modern carriers of operational oceanography for the purpose of ecological diagnostics of the world ocean using autochthonous plankton are discussed. The results of field measurements of plankton using miniDHC as part of a hydrobiological probe are presented and interpreted, and their verification is carried out. The results of comparing the data on the concentration of individual taxa obtained using miniDHC with the data obtained by the traditional method using plankton catching with a net showed a difference of no more than 23%. The article also contains recommendations for expanding the potential of miniDHC, its purpose indicators, and improving metrological characteristics.

scholarly journals Laboratory and In Situ Determination of Hydraulic Conductivity and Their Validity in Transient Seepage Analysis

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1131
Author(s):  
Soonkie Nam ◽  
Marte Gutierrez ◽  
Panayiotis Diplas ◽  
John Petrie
Keyword(s):  
Hydraulic Conductivity ◽  
Field Measurements ◽  
Natural Soil ◽  
In Situ Tests ◽  
Seepage Analysis ◽  
Soil Deposits ◽  
Seepage Modeling ◽  
Sample Disturbance

This paper critically compares the use of laboratory tests against in situ tests combined with numerical seepage modeling to determine the hydraulic conductivity of natural soil deposits. Laboratory determination of hydraulic conductivity used the constant head permeability and oedometer tests on undisturbed Shelby tube and block soil samples. The auger hole method and Guelph permeameter tests were performed in the field. Groundwater table elevations in natural soil deposits with different hydraulic conductivity values were predicted using finite element seepage modeling and compared with field measurements to assess the various test results. Hydraulic conductivity values obtained by the auger hole method provide predictions that best match the groundwater table’s observed location at the field site. This observation indicates that hydraulic conductivity determined by the in situ test represents the actual conditions in the field better than that determined in a laboratory setting. The differences between the laboratory and in situ hydraulic conductivity values can be attributed to factors such as sample disturbance, soil anisotropy, fissures and cracks, and soil structure in addition to the conceptual and procedural differences in testing methods and effects of sample size.

Weathering, structure and in situ stress in residual soils

Géotechnique ◽  
1984 ◽  
Vol 34 (1) ◽  
pp. 43-59 ◽  
Author(s):  
P. R. Vaughan ◽  
C. W. Kwan
Keyword(s):  
In Situ Stress ◽  
Residual Soils

scholarly journals The Interaction Features of the Multi-Level Retaining Walls with Soil Mass

2017 ◽  
Vol 26 (3) ◽  
pp. 179-190
Author(s):  
Igor Boyko ◽  
Liudmyla Skochko ◽  
Veronica Zhuk
Keyword(s):  
Numerical Modelling ◽  
Numerical Simulations ◽  
Variable Stiffness ◽  
Retaining Walls ◽  
Soil Mass ◽  
Soil Base ◽  
Deep Foundation ◽  
Multi Level ◽  
Horizontal Displacements

Abstract The interaction features of multi-level retaining walls with soil base were researched by changing their geometric parameters and locality at the plan. During excavation of deep foundation pits it is important to choose the type of constructions which influences on the horizontal displacements. The distance between the levels of retaining walls should be based on the results of numerical modelling. The objective of this paper is to present a comparison between the data of numerical simulations and the results of the in-situ lateral tests of couple piles. The problems have been solved by using the following soil models: Coulomb-Mohr model; model, which is based on the dilatation theory; elastic-plastic model with variable stiffness parameters.

Assessment of Moisture Content in Sandy Beach Environments from Multispectral Satellite Imagery

2021 ◽  
Author(s):  
Julie Paprocki ◽  
Nina Stark ◽  
Hans C Graber ◽  
Heidi Wadman ◽  
Jesse E McNinch
Keyword(s):  
Moisture Content ◽  
Laboratory Data ◽  
Field Measurements ◽  
Weather Conditions ◽  
Sandy Beaches ◽  
Percent Error ◽  
Moisture Contents ◽  
Multispectral Satellite Imagery ◽  
Factor C

A framework for estimating moisture content from satellite-based multispectral imagery of sandy beaches was tested under various site conditions and sensors. It utilizes the reflectance of dry soil and an empirical factor c relating reflectance and moisture content for specific sediment. Here, c was derived two ways: first, from in-situ measurements of moisture content and average NIR image reflectance; and second, from laboratory-based measurements of moisture content and spectrometer reflectance. The proposed method was tested at four sandy beaches: Duck, North Carolina, and Cannon Beach, Ocean Cape, and Point Carrew, Yakutat, Alaska. Both measured and estimated moisture content profiles were impacted by site geomorphology. For profiles with uniform slopes, moisture contents ranged from 3.0%-8.0% (Zone 1) and from 8.0%-23.0% (Zone 2). Compared to field measurements, the moisture contents estimated using c calibrated from in-situ and laboratory data resulted in percent error of 3.6%-44.7% and 2.7%-58.6%, respectively. The highest percent error occurred at the transition from Zone 1 to Zone 2. Generally, moisture contents were overestimated in Zone 1 and underestimated in Zone 2, but followed the expected trends based on field measurements. When estimated moisture contents in Zone 1 exceeded 10%, surface roughness, debris, geomorphology, and weather conditions were considered.

Geochemical evaluation of the in-situ regolith of Madengi hills of Dodoma, Tanzania. Implication on bedrock mapping and delineating gold mineralization target

2021 ◽  
pp. geochem2021-074
Author(s):  
Godson Godfray
Keyword(s):  
Gold Mineralization ◽  
Early Stage ◽  
Shear Zones ◽  
Soil Geochemistry ◽  
Residual Soils ◽  
Content Type ◽  
Geochemical Evaluation ◽  
Supplementary Material ◽  
Pathfinder Elements

Successful gold exploration projects depend on a piece of clear information on the association between gold, trace elements, and mineralization controlling factors. The use of soil geochemistry has been an important tool in pinpointing exploration targets during the early stage of exploration. This study aimed to establish the gold distribution, the elemental association between gold and its pathfinder elements such as Cu, Zn, Ag, Ni, Co, Mn, Fe, Cd, V, Cr, Ti, Sc, In, and Se and identify lithologies contributing to the overlying residual soils. From cluster analysis, a high similarity level of 53.93% has been shown with Ag, Cd, and Se at a distance level of 0.92. Au and Se have a similarity level of 65.87% and a distance level of 0.68, hence is proposed to be the most promising pathfinder element. PCA, FA, and the Pearson's correlation matrix of transformed data of V, Cu, Ni, Fe, Mn, Cr, and Co and a stronger correlation between Pb and U, Th, Na, K, Sn, Y, Ta and Be shows that source gold mineralization might be associated with both hornblende gneisses interlayered with quartzite, tonalite, and tonalitic orthogneiss. From the contour map and gridded map of Au and its pathfinder elements, it has been noted that their anomalies and target generated are localized in the Northern part of the area. The targets trend ESE to WNW nearly parallel to the shear zones as a controlling factor of Au mineralization emplacement.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5721965

In-situ Full Field Measurements During Inter-Facial Debonding in Single Fiber Composite Under Transverse Load

2018 ◽  
Vol 58 (9) ◽  
pp. 1451-1467 ◽  
Author(s):  
I. Tabiai ◽  
R. Delorme ◽  
D. Therriault ◽  
M. Levesque
Keyword(s):  
Fiber Composite ◽  
Field Measurements ◽  
Single Fiber ◽  
Transverse Load ◽  
Full Field
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