Observations on some basal failures in sheeted excavations

1970 ◽  
Vol 7 (2) ◽  
pp. 136-144 ◽  
Author(s):  
V. Milligan ◽  
K. Y. Lo
Keyword(s):  
Shear Strength ◽  
Ground Water ◽  
Groundwater Level ◽  
Soil Conditions ◽  
Remedial Measures ◽  
Factors Influencing ◽  
Water Head ◽  
The Stability ◽  
Made In

In excavations below groundwater level, instability of the base may result from the inflow of water into the excavation. The most important factors influencing the stability are the ground water and detailed soil conditions at the site.Construction problems encountered in excavations in clay strata, underlain by pervious water bearing layers, are described. The remedial measures adopted in each case are also discussed. From a study of the observations made in the case records, it is suggested that excavation in intact clays may be carried out to depths exceeding that limited by the ratio of t/h = 0.5, where t is the distance from the bottom of the excavation to the top of the water bearing stratum, and h is the water head at the top of the water bearing stratum, provided that the clay is not disturbed during construction so that the shear strength of the clay is preserved.

scholarly journals Earthflows at the Beattie Mine Quebec, Canada

1964 ◽  
Vol 1 (2) ◽  
pp. 104-114 ◽  
Author(s):  
W J Eden
Keyword(s):  
Soil Conditions ◽  
Remedial Measures ◽  
Sequence Of Events ◽  
The Stability ◽  
Clay Slopes ◽  
Varved Clay

In June 1943 an earthflow involving more than one million cubic yards of varved clay occurred at the Beattie Mine. Subsequent remedial measures resulted in further large landslides. This paper describes the soil conditions, the sequence of events, and attempts to assess the stability of the clay slopes. It was found that the undrained analysis led to an unsafe assessment but that Terzaghi's rule for critical heights of slope gave a better indication of stability.

Analysis of slope stability at Goonyella Mine

1981 ◽  
Vol 18 (2) ◽  
pp. 179-194 ◽  
Author(s):  
B. G. Richards ◽  
M. A. Coulthard ◽  
C. T. Toh
Keyword(s):  
Shear Strength ◽  
Numerical Methods ◽  
Coal Mine ◽  
Stress Relief ◽  
Dominant Factor ◽  
Remedial Measures ◽  
Laboratory Studies ◽  
Planar Surfaces ◽  
Factors Influencing ◽  
Significant Factors

Since the commencement of mining at the strip coal mine at Goonyella, Queensland, Australia, serious stability problems have been experienced in both the spoil piles and the highwalls. A collaborative investigation was commenced in 1974 and the significant factors influencing stability have now been defined. This paper outlines the results of field and laboratory studies associated with the investigation and describes the various numerical methods used to analyse stability. The main conclusions, which are similar for both the spoil piles and the highwalls, are that the failures generally occur along two or three planar surfaces; that the shear strength in the basal areas is controlled by the sensitivity of the materials to moisture and shear strain prior to failure; and that tensile cracking due to stress relief and blasting is the dominant factor in the upper or escarpment areas. Possible control and remedial measures are discussed briefly.

Undrained stability of rectangular tunnels where shear strength increases linearly with depth

2017 ◽  
Vol 54 (4) ◽  
pp. 469-480 ◽  
Author(s):  
Daniel W. Wilson ◽  
Andrew J. Abbo ◽  
Scott W. Sloan ◽  
Kentaro Yamamoto
Keyword(s):  
Finite Element ◽  
Shear Strength ◽  
Optimization Problem ◽  
Soil Conditions ◽  
Discrete Form ◽  
Element Mesh ◽  
Classical Plasticity ◽  
Undrained Conditions ◽  
The Stability ◽  
Rectangular Tunnel

This paper investigates the stability of a plane strain rectangular tunnel under undrained conditions, where the shear strength profile increases linearly with depth. The undrained stability of tunnels for a range of geometries and soil conditions is found using rigid-block upper bound methods as well as finite element limit analysis (FELA). The latter procedures employ a discrete form of the bound theorems of classical plasticity to formulate an optimization problem that is solved using a bespoke conic programming scheme. Rigorous solutions, obtained using adaptive re-meshing of the finite element mesh, generally bracket the true collapse load with upper and lower bound solutions to within 2%. Results from the parametric study are summarized in the form of stability charts.

Current literature review on methods for measuring the stability of osseointegrable implants.

2020 ◽  
Vol 2 (4) ◽  
pp. 64-78
Author(s):  
Noha El-Wassefy ◽  
Lars Sennerby ◽  
Dhoom SIngh Mehta ◽  
Thiago De Santana Santos
Keyword(s):  
Literature Review ◽  
Current Literature ◽  
Implant Survival ◽  
Implant Stability ◽  
Implant Placement ◽  
Factors Influencing ◽  
Case Documentation ◽  
Bone To Implant Contact ◽  
The Stability

“Osseointegration” as formulated by Alberktson is crucial for implant survival and success. Osseointegration is a measure of implant stability. Measuring implant stability helps to arrive at decisions as to loading of an implant, allows choice of protocol on a patient to patient basis and provides better case documentation. A successful implant reflects good bone to implant contact and is determined by implant stability both primary and secondary. Implant stability is achieved at two different stages – primary (immediately after implant placement) and secondary (3-4 months after implant placement). Implant stability has been confirmed to affect the process of osseointegration and therefore is essential to understand the methods to measure implant stability and factors influencing. Various methods are developed to assess implant stability which suggests the prognosis of an implant.

Slope Stability Analysis under the Condition of Seepage

2012 ◽  
Vol 204-208 ◽  
pp. 241-245
Author(s):  
Yang Jin
Keyword(s):  
Finite Element Method ◽  
Shear Strength ◽  
Slope Stability ◽  
Negative Impact ◽  
Strength Reduction ◽  
Soil Slope ◽  
Failure State ◽  
Calculation Results ◽  
The Stability ◽  
Shear Strength Reduction

The stability of soil slope under seepage is calculated and analyzed by using finite element method based on the technique of shear strength reduction. When the condition of seepage or not is considered respectively, the critical failure state of slopes and corresponding safety coefficients can be determined by the numerical analysis and calculation. Besides, through analyzing and comparing the calculation results, it shows that seepage has a negative impact on slope stability.

scholarly journals Monitoring the Impact of the Large Building Investments on the Neighborhood

2021 ◽  
Vol 11 (14) ◽  
pp. 6537
Author(s):  
Marian Łupieżowiec
Keyword(s):  
Groundwater Level ◽  
Soil Improvement ◽  
Deep Excavation ◽  
Large Area ◽  
Safety Measures ◽  
High Rise ◽  
The Impact ◽  
Large Building ◽  
Additional Safety ◽  
Made In

The article presents the concept of monitoring buildings and infrastructure elements located near large construction investments (the construction of high-rise buildings of the Oak Terraces housing estate in Katowice and the construction of a tunnel under the roundabout in Katowice along the intercity express road DTŚ). The impacts include deep excavation, lowering of the groundwater level over a large area, and dynamic influences related to the use of impact methods of soil improvement. The presented monitoring includes observation of the groundwater level with the use of piezometers, geodetic measurements of settlement and inclinations, as well as the measurement of vibration amplitudes generated during the works involving shocks and vibrations. It was also important to observe the development of cracks on the basis of a previously made inventory of damage. The results of the monitoring allow corrections to be made in the technology of works (e.g., reduction of vibration amplitudes, application of additional protections at excavations, etc.) or the use additional safety measures. Currently, there are also monitoring systems used during the operation of completed facilities.

Stability of spinosad resistance inFrankliniella occidentalis(Pergande) under laboratory conditions

2008 ◽  
Vol 98 (4) ◽  
pp. 355-359 ◽  
Author(s):  
P. Bielza ◽  
V. Quinto ◽  
C. Grávalos ◽  
E. Fernández ◽  
J. Abellán ◽  
...  
Keyword(s):  
Resistant Strain ◽  
Selection Pressure ◽  
Frankliniella Occidentalis ◽  
Western Flower Thrips ◽  
Laboratory Conditions ◽  
Flower Thrips ◽  
Factors Influencing ◽  
Stability Of Resistance ◽  
The Stability ◽  
Successive Generations

AbstractThe stability of spinosad resistance in western flower thrips (WFT),Frankliniella occidentalis(Pergande), populations with differing initial frequencies of resistance was studied in laboratory conditions. The stability of resistance was assessed in bimonthly residual bioassays in five populations with initial frequencies of 100, 75, 50, 25 and 0% of resistant individuals. There were no consistent changes in susceptibility of the susceptible strain after eight months without insecticide pressure. In the resistant strain, very highly resistant to spinosad (RF50>23,000-fold), resistance was maintained up to eight months without further exposure to spinosad. In the absence of any immigration of susceptible genes into the population, resistance was stable. In the case of the population with different initial frequency of resistant thrips, spinosad resistance declined significantly two months later in the absence of selection pressure. With successive generations, these strains did not change significantly in sensitivity. Spinosad resistance inF. occidentalisdeclined significantly in the absence of selection pressure and the presence of susceptible WFT. These results suggest that spinosad resistance probably is unstable under field conditions, primarily due to the immigration of susceptible WFT. Factors influencing stability or reversion of spinosad resistance are discussed.

An experiment in the control of the ground water-level in a fen peat soil

1951 ◽  
Vol 41 (1-2) ◽  
pp. 149-162 ◽  
Author(s):  
H. H. Nicholson ◽  
G. Alderman ◽  
D. H. Firth
Keyword(s):  
Ground Water ◽  
Water Level ◽  
Large Scale ◽  
Field Experiments ◽  
Peat Soil ◽  
Climatic Conditions ◽  
Ground Water Level ◽  
Effective Control ◽  
Soil Conditions ◽  
Local Soil

1. The methods of investigation of the effect of ground water-level on crop growth, together with tho field installations in use, are discussed.2. Direct field experiments are handicapped by the difficulties of achieving close control on a sufficiently large scale, due to considerable variations of surface level and depth of peat within individual fields and to rapid fluctuations in rainfall and evaporation. Many recorded experiments are associated with climatic conditions of substantial precipitation during the growing season.3. Seasonal fluctuations of ground water-level in Fen peat soils in England, in natural and agricultural conditions, are described.4. The local soil conditions are outlined and the implications of profile variations are discussed.5. The effective control of ground water-level on a field scale requires deep and commodious ditches and frequent large underdrains to ensure the movement of water underground with sufficient freedom to give rapid compensatory adjustment for marked disturbances of ground water-level following the incidence of heavy rain or excessive evaporation.6. A working installation for a field experiment in ordinary farming conditions is described and the measure of control attained is indicated.

scholarly journals Comparison of Selected Terramechanical Test Procedures and Cartographic Indices to Predict Rutting Caused by Machine Traffic during a Cut-to-Length Thinning Operation

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 113
Author(s):  
Marian Schönauer ◽  
Stephan Hoffmann ◽  
Joachim Maack ◽  
Martin Jansen ◽  
Dirk Jaeger
Keyword(s):  
Shear Strength ◽  
Penetration Depth ◽  
Sustainable Forest Management ◽  
Operating Conditions ◽  
Soil Conditions ◽  
Cone Penetration ◽  
Topographic Wetness Index ◽  
Mixed Stands ◽  
Thinning Operation ◽  
Cone Index

Timber harvesting operations using heavy forest machinery frequently results in severe soil compaction and displacement, threatening sustainable forest management. An accurate prediction of trafficability, considering actual operating conditions, minimizes these impacts and can be facilitated by various predictive tools. Within this study, we validated the accuracy of four terramechanical parameters, including Cone Index (MPa, Penetrologger), penetration depth (cm, Penetrologger), cone penetration (cm blow−1, dual-mass dynamic cone penetrometer) and shear strength (kPa, vane meter), and additionally two cartographic indices (topographic wetness index and depth-to-water). Measurements applying the four terramechanical approaches were performed at 47 transects along newly assigned machine operating trails in two broadleaved dominated mixed stands. After the CTL thinning operation was completed, measurement results and cartographic indices were correlated against rut depth. Under the rather dry soil conditions (29 ± 9 vol%), total rut depth ranged between 2.2 and 11.6 cm, and was clearly predicted by rut depth after a single pass of the harvester, which was used for further validations. The results indicated the easy-to-measure penetration depth as the most accurate approach to predict rut depth, considering coefficients of correlation (rP = 0.44). Moreover, cone penetration (rP = 0.34) provided reliable results. Surprisingly, no response between rut depth and Cone Index was observed, although it is commonly used to assess trafficability. The relatively low moisture conditions probably inhibited a correlation between rutting and moisture content. Consistently, cartographic indices could not be used to predict rutting. Rut depth after the harvester pass was a reliable predictor for total rut depth after 2–5 passes (rP = 0.50). Rarely used parameters, such as cone penetration or shear strength, outcompeted the highly reputed Cone Index, emphasizing further investigations of applied tools.

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