Regional distribution of in situ horizontal stresses in rocks of Southern Ontario

1978 ◽  
Vol 15 (3) ◽  
pp. 371-381 ◽  
Author(s):  
K. Y. Lo
Keyword(s):  
Regional Distribution ◽  
Concrete Lining ◽  
Underground Structures ◽  
Case Histories ◽  
Southern Ontario ◽  
In Situ Stresses ◽  
Rock Formations ◽  
Direct Measurements

Some structures built in different rock formations in Southern Ontario have been subjected to various degrees of distress. These case histories include heaves of quarry bottoms, buckling of concrete lining of canal floors, cracking of concrete lining of tunnels at the springline, and long term movement of the walls of unsupported excavations.Inference from these case histories, together with direct measurements of in situ stresses, indicate that high horizontal stresses exist in the Silurian and Ordovician rocks. The magnitude of the maximum stress in the horizontal plane varies from 6–14 MPa depending on the depth and rock type.Excavations in rock relieve the in situ stresses. The stress relief serves as an initiating mechanism for time-dependent deformation to occur leading to the process loosely termed as 'rock squeeze'. It appears, therefore, that due consideration must be given to this prevalent phenomenon for the design of underground structures in rock in this region.

scholarly journals A cement paste–tail sealant interface modified with a silane coupling agent for enhancing waterproofing performance in a concrete lining system

RSC Advances ◽  
2019 ◽  
Vol 9 (13) ◽  
pp. 7165-7175 ◽  
Author(s):  
Fan Li ◽  
Yuyou Yang ◽  
Mingjiang Tao ◽  
Xiangqian Li
Keyword(s):  
Cement Paste ◽  
Coupling Agent ◽  
Surface Coating ◽  
Silane Coupling Agent ◽  
Hydrophobic Surface ◽  
Concrete Lining ◽  
Underground Structures ◽  
System P ◽  
Silane Coupling

Although hydrophobic surface coating of concrete is currently used to enhance waterproofing performance of underground structures, the chemical and mechanical incompatibility between them is a challenge to ensure long-term waterproofing properties.

scholarly journals Design of underground structures and analysis of self-support capacity

2018 ◽  
Vol 65 (2) ◽  
pp. 59-70
Author(s):  
Matej Nagy
Keyword(s):  
Rock Mass ◽  
Hard Rock ◽  
In Situ Stress ◽  
Stability Control ◽  
Underground Structures ◽  
Underground Powerhouse ◽  
The Stability ◽  
Methods Numerical

Abstract The complicated rock structures and the stability of surrounding rocks of the underground powerhouse are key ground mechanical challenges for hydropower projects. In this paper, an example of contributing self-support capacity of rock mass to evaluate optimised support for long-term usage of structure is given. It describes importance of investigations in the initial in situ stress distribution, rock mechanical and geological properties, engineering rock mass classifications by different methods, numerical modelling, comparison of tools for stability and support analysis and proper stability control for rock excavation and support. The results show that after underground excavations in hard rock, detailed analysis of measures to investigate deformation and self-supporting capacity creation is useful and a cost-saving procedure.

Taking on Looting: Pursuing Sustainable Site Protection Policies in Southern Ontario

2021 ◽  
Vol 45 (1) ◽  
pp. 20-52
Author(s):  
Daniel A. Ionico
Keyword(s):  
First Nations ◽  
Collective Responsibility ◽  
Archaeological Remains ◽  
Southern Ontario ◽  
Property Owners ◽  
The Future ◽  
History Of ◽  
Sustainable Protection

Centuries of looting has repeatedly unearthed the archaeological remains of First Nations middens, villages, and cemeteries. This paper presents a case for new measures to curtail these illicit practices in Ontario. Over the last decade, many archaeologists have espoused a program of sustainable archaeology. I suggest protections of in situ contexts against looting will further the objectives of sustainable archaeology and contribute to this broader trajectory of practice in the province. Using the history of looting and archaeological conditions at Neutral Iroquoian (Attawandaron) sites, along with information from modern collectors, the paper reveals the persistent threat of looting and the necessity for action. I suggest the province, municipalities, and archaeological stakeholders deploy policies aimed at preserving these resources into the future. I advocate for a stewardship of personal and collective responsibility among property owners and hobbyists through educational initiatives, legal easement agreements, and existing legislative mandates to serve as a pragmatic step towards the long-term sustainable protection of these sites.

Time-dependent deformation of shaly rocks in southern Ontario

1978 ◽  
Vol 15 (4) ◽  
pp. 537-547 ◽  
Author(s):  
K. Y. Lo ◽  
R. S. C. Wai ◽  
J. H. L. Palmer ◽  
R. M. Quigley
Keyword(s):  
Time Dependent ◽  
Model Parameters ◽  
Deformation Model ◽  
Test Results ◽  
Southern Ontario ◽  
Rock Types ◽  
Rock Formations ◽  
Swelling Characteristics ◽  
Field Behaviour

Two methods of laboratory measurements of time-dependent deformations of rocks due to the relief of in situ stresses are described. Experiments were performed on specimens taken from seven rock formations in southern Ontario. It was found that some rock types exhibit considerable time-dependent deformation, generally consistent with observed field behaviour. In addition, the swelling behaviour of the shaly rocks is anisotropic and constituent layers of the same rock formation may possess very different swelling characteristics. Mineralogical tests performed showed that the observed swelling behaviours are related to the composition and clay fabric of the rock.For detailed analysis of the test results, a rheological model was employed to represent the time-dependent deformation. Model parameters for three rock types have been obtained.Because the tests are simple and inexpensive to perform, it becomes practical to carry out a large number of tests for the evaluation of potential problems due to time-dependent deformation.

scholarly journals The Research on Borehole Stability in Depleted Reservoir and Caprock: Using the Geophysics Logging Data

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Junliang Yuan ◽  
Jingen Deng ◽  
Yong Luo ◽  
Shisheng Guo ◽  
Haishan Zhang ◽  
...  
Keyword(s):  
Pore Pressure ◽  
Oil And Gas ◽  
Geomechanical Model ◽  
Borehole Stability ◽  
In Situ Stresses ◽  
Pressure Depletion

Long-term oil and gas exploitation in reservoir will lead to pore pressure depletion. The pore pressure depletion will result in changes of horizontal in-situ stresses both in reservoirs and caprock formations. Using the geophysics logging data, the magnitude and orientation changes of horizontal stresses in caprock and reservoir are studied. Furthermore, the borehole stability can be affected by in-situ stresses changes. To address this issue, the dehydration from caprock to reservoir and roof effect of caprock are performed. Based on that, the influence scope and magnitude of horizontal stresses reduction in caprock above the depleted reservoirs are estimated. The effects of development on borehole stability in both reservoir and caprock are studied step by step with the above geomechanical model.

Performance of a small tunnel in clay shale

1987 ◽  
Vol 24 (2) ◽  
pp. 297-307
Author(s):  
R. C. K. Wong ◽  
P. K. Kaiser
Keyword(s):  
Rock Mass ◽  
Rock Properties ◽  
Triaxial Tests ◽  
Concrete Lining ◽  
Short Term ◽  
Tunnel Wall ◽  
Element Analysis ◽  
Clay Shale

The tunnel described in this paper was hand-excavated through Upper Cretaceous clay shale and temporarily supported by steel ribs and spruce laggings. A cast-in-place concrete lining was installed for permanent support. Tunnel wall convergences and support stresses and strains were monitored for more than 100 days. In addition to the field instrumentation, in situ pressuremeter tests and laboratory triaxial tests on specimens taken from a block sample were performed to determine the rock mass properties. These properties were used to interpret (by finite element analysis) the measured tunnel wall deformations. In general, the short-term rock properties determined from laboratory testing agreed well with the observed in situ behaviour. The long-term response was, however, difficult to predict from laboratory measurements and this was further investigated by application of the convergence–confinement method. It was found that the equivalent, long-term modulus of the rock mass decreased with time to between 50 and 70% of the short-term modulus. The deformation rates decreased significantly after 70–100 days and the support load levelled off accordingly. Key words: tunnel, monitoring, clay shale, temporary support.

scholarly journals Global soil moisture data derived through machine learning trained with in-situ measurements

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Sungmin O. ◽  
Rene Orth
Keyword(s):  
Machine Learning ◽  
Soil Moisture ◽  
Large Scale ◽  
Short Term Memory ◽  
Temporal Dynamics ◽  
Soil Moisture Data ◽  
Wide Range ◽  
Global Soil

AbstractWhile soil moisture information is essential for a wide range of hydrologic and climate applications, spatially-continuous soil moisture data is only available from satellite observations or model simulations. Here we present a global, long-term dataset of soil moisture derived through machine learning trained with in-situ measurements, SoMo.ml. We train a Long Short-Term Memory (LSTM) model to extrapolate daily soil moisture dynamics in space and in time, based on in-situ data collected from more than 1,000 stations across the globe. SoMo.ml provides multi-layer soil moisture data (0–10 cm, 10–30 cm, and 30–50 cm) at 0.25° spatial and daily temporal resolution over the period 2000–2019. The performance of the resulting dataset is evaluated through cross validation and inter-comparison with existing soil moisture datasets. SoMo.ml performs especially well in terms of temporal dynamics, making it particularly useful for applications requiring time-varying soil moisture, such as anomaly detection and memory analyses. SoMo.ml complements the existing suite of modelled and satellite-based datasets given its distinct derivation, to support large-scale hydrological, meteorological, and ecological analyses.

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