Experiences with shored excavations

1987 ◽  
Vol 24 (2) ◽  
pp. 267-278
Author(s):  
W. A. Trow
Keyword(s):  
Soil Mechanics ◽  
Pressure Coefficient ◽  
Earth Pressure ◽  
Foundation Engineering ◽  
Active Earth Pressure ◽  
Case Histories ◽  
Pressure Coefficients ◽  
The Earth ◽  
Earth Pressure Coefficient ◽  
Selection Of

This paper considers shoring of excavations associated with construction of buildings with particular reference to the selection of the earth pressure coefficient. The empirical criteria, given by R. B. Peck and other participants at the International Conference on Soil Mechanics and Foundation Engineering in Mexico City in 1969, are examined. Several case histories of deep excavations are given where acceptable deformations were experienced using active earth pressure coefficients in shoring design. Where failure occurred, it was attributed to causes unrelated to the selection of earth pressure coefficient. Key words: shoring, earth pressure coefficient, deformations.

scholarly journals Numerical investigation of earth pressure coefficient along central line of backfilled stopes

2017 ◽  
Vol 54 (1) ◽  
pp. 138-145 ◽  
Author(s):  
Mohamed Amine Sobhi ◽  
Li Li ◽  
Michel Aubertin
Keyword(s):  
Pressure Coefficient ◽  
Earth Pressure ◽  
Central Line ◽  
Simple Expression ◽  
Active Earth Pressure ◽  
Principal Stresses ◽  
The Earth ◽  
Earth Pressure Coefficient ◽  
Backfilled Stopes ◽  
Key Parameter

The earth pressure coefficient K, defined as the horizontal to vertical normal (effective) stresses ratio (σh/σv), is a key parameter in analytical solutions for estimating the stresses in backfilled stopes. In the case of vertical stopes, the value of K has sometimes been defined using the at-rest earth pressure coefficient K0, while others have applied Rankine’s active earth pressure coefficient Ka. To help clarify this confusing situation, which can lead to significantly different results, the origin and nature of the at-rest and Rankine’s active coefficients are first briefly recalled. The stress state in backfilled stopes is then investigated using numerical simulations. The results indicate that the value of K can be close to Ka for cohesionless backfills along the vertical central line (CL) of vertical stopes, due to sequential placement and partial yielding of the backfill. For inclined stopes, simulations show that the ratio between the minor and major principal stresses (σ3/σ1) along the CL in the backfill, which differs from σh/σv, can also be close to Ka. A simple expression is shown to represent the horizontal to vertical stresses ratio σh/σv (= K) along the CL of such inclined stopes well. A discussion follows on the effects of backfill properties and simulation approach.

Exact determination of gravity stresses in finite elastic slopes: Part II. Applications

1983 ◽  
Vol 20 (1) ◽  
pp. 55-60 ◽  
Author(s):  
V. Silvestri ◽  
C. Tabib
Keyword(s):  
Exact Solution ◽  
Pressure Coefficient ◽  
Earth Pressure ◽  
Influence Diagrams ◽  
A Value ◽  
The Earth ◽  
Exact Determination ◽  
Earth Pressure Coefficient ◽  
Numerical Finite Element

Influence diagrams are presented for the gravity stresses arising in excavated finite elastic slopes inclined at various angles, −β (β = π/2, π/3, π/4, π/6, and π/8), with respect to the horizontal. These influence diagrams are calculated for a value of the earth pressure coefficient at rest, K0, equal to 0.50. Several examples are worked out and adequately illustrate the application of the influence charts and of the general solution. Finally, the results obtained from the exact solution are compared with those published in the literature, which were obtained by means of numerical (finite element) and experimental (photoelasticity) methods.

An examination of some theories of earth pressure on shaft linings

1977 ◽  
Vol 14 (1) ◽  
pp. 91-106 ◽  
Author(s):  
E. G. Prater
Keyword(s):  
Pressure Coefficient ◽  
Earth Pressure ◽  
Failure Surface ◽  
Cohesionless Soils ◽  
The Earth ◽  
Earth Pressures ◽  
Coulomb Type ◽  
Earth Pressure Coefficient ◽  
The One ◽  
Similar Theory

Various theories for determining the earth pressure on shaft linings in cohesionless soils are discussed, and results are presented for a Coulomb-type analysis with a conical sliding surface. The assumed shape of the failure surface approximates closely the one given in published results obtained by the method of characteristics. The simplicity of the cone permits an investigation of a number of parameters, e.g. the earth pressure coefficient on radial planes, which turns out to be a decisive parameter in the analysis, and accounts for the widely differing published values for earth pressures on shaft linings. Certain theories could lead, especially at greater depths, to rather conservative designs.A similar theory is also presented for earth pressures on shafts in cohesive soils. In this case the possibility of base failure must be considered as well, and it is shown that this might be the deciding failure mechanism.

Active pressure on gravity walls supporting purely frictional soils

2012 ◽  
Vol 49 (1) ◽  
pp. 78-97 ◽  
Author(s):  
D. Loukidis ◽  
R. Salgado
Keyword(s):  
Critical State ◽  
Soil Mechanics ◽  
Retaining Wall ◽  
Pressure Coefficient ◽  
Earth Pressure ◽  
Friction Angle ◽  
Soil Mass ◽  
Active Earth Pressure ◽  
Foundation Soil ◽  
Surface Plasticity

The active earth pressure used in the design of gravity walls is calculated based on the internal friction angle of the retained soil or backfill. However, the friction angle of a soil changes during the deformation process. For drained loading, the mobilized friction angle varies between the peak and critical-state friction angles, depending on the level of shear strain in the retained soil. Consequently, there is not a single value of friction angle for the retained soil mass, and the active earth pressure coefficient changes as the wall moves away from the backfill and plastic shear strains in the backfill increase. In this paper, the finite element method is used to study the evolution of the active earth pressure behind a gravity retaining wall, as well as the shear patterns developing in the backfill and foundation soil. The analyses relied on use of a two-surface plasticity constitutive model for sands, which is based on critical-state soil mechanics.

scholarly journals Research on the Earth Pressure and Internal Force of a High-Fill Open-Cut Tunnel Using a Bilayer Lining Design: A Field Test Using an FBG Automatic Data Acquisition System

Sensors ◽  
2019 ◽  
Vol 19 (7) ◽  
pp. 1487 ◽  
Author(s):  
Tianyuan Xu ◽  
Mingnian Wang ◽  
Li Yu ◽  
Cheng Lv ◽  
Yucang Dong ◽  
...  
Keyword(s):  
Field Test ◽  
Soil Column ◽  
Pressure Coefficient ◽  
Earth Pressure ◽  
Internal Force ◽  
Automatic Data ◽  
The Earth ◽  
New Type ◽  
Earth Pressure Coefficient ◽  
Two Stages

When there are railway tunnels on both sides of a valley, a bridge is usually built to let trains pass. However, if the valley is very close to an urban area, building an open-cut tunnel at the portal and then backfilling it to create available land resources for the city and to prevent excavation slag from polluting the environment would be a wise choice. This has led to the emergence of a new type of structure, namely, the high-fill open-cut tunnel. In this paper, by performing an automatic long-term field test on the first high-fill open-cut tunnel using a bilayer design in China, the variations of earth pressure and structural internal force during the backfilling process were obtained, and different tunnel foundation types were studied. The results showed that the earth pressure significantly exceeded the soil column weight, with a maximum earth pressure coefficient between 1.341 and 2.278. During the backfilling process, the earth pressure coefficient increased at first and then decreased slowly to a relatively stable value, and a stiffer foundation would make the structure bear higher earth pressure (1.69 times the normal one observed during monitoring). The change of internal force had two stages during backfilling: before the backfill soil reached the arch crown, the internal force of the lining changed slowly and then grew linearly as the backfill process continued. Moreover, the axial force ratio of the inner and outer linings was close to their thickness proportion, and the interaction mode between the two layers was very similar to the composite beam.

scholarly journals Calculation of active earth pressure on retaining walls with line surcharge effect and presentation of design diagrams in cohesive – frictional soils

2021 ◽  
Vol 34 (01) ◽  
pp. 242-257
Author(s):  
Mojtaba Ahmadabadi ◽  
Mohammad Karim Faghirizadeh
Keyword(s):  
Pressure Coefficient ◽  
Earth Pressure ◽  
Soil Parameters ◽  
Active Earth Pressure ◽  
Angle Of Internal Friction ◽  
Numerical Software ◽  
Earth Pressure Coefficient ◽  
Comparison Of The Results ◽  
Failure Wedge ◽  
Frictional Soils

In this study, a formulation and models have been proposed to calculate the active earth pressure on the wall and to determine the angle of failure wedge with line surcharge effect and taking into account the soil cohesion. The proposed method has the advantage of taking into account soil parameters such as cohesion, the angle of friction between the soil and the wall, the surcharge effect in the elasto-plastic environment, and the range that determines the critical surcharge. This paper presents dimensionless diagrams for different soil specifications and surcharges. According to these diagrams, it is easy to determine the distribution of excess pressure caused by surcharge, the distribution of the total active earth pressure on the wall, the angle of the failure wedge as well as the minimum and maximum active coefficient of the pressure with respect to surcharge distance. Furthermore, all soil parameters, surcharge and the results have been addressed. In general, the results indicated that increasing the angle of internal friction of the soil and cohesion would result to a nonlinear reduction in the active earth pressure coefficient, contrary to the line surcharge, which increases the active earth pressure of the soil and ultimately increases the active earth pressure coefficient. In this research, a diagram has been presented that expresses the surface that the active earth pressure coefficient changes with respect to the surcharge distance. The lower limit of each graph expresses the minimum active earth pressure coefficient (kas (min)) at the minimum surcharge distance, whereas the upper limit indicates the maximum active earth pressure coefficient (kas (max)) at the maximum surcharge distance from the wall. Comparison of the results of the proposed method with previous methods, codes and numerical software shows that in general, the proposed method is able to simplify the analysis of walls with surcharge effect in cohesive-frictional soils. In addition to the formulation and diagrams, a computer program in MATLAB software has been written. Using the results of these codes, the pressure on the wall with the linear surcharge effect, angle of failure wedge and pressure distribution on the wall in the cohesive-frictional soils can be calculated for all scenarios.

scholarly journals Probabilistic analysis of the active earth pressure on earth retaining walls for c-ϕ soils according to the Mazindrani and Ganjali method

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Julian Osorio ◽  
Juan Camilo Viviescas ◽  
Juan Pablo Osorio
Keyword(s):  
Probabilistic Analysis ◽  
Earth Pressure ◽  
Friction Angle ◽  
Retaining Walls ◽  
Soil Variability ◽  
Active Earth Pressure ◽  
Pressure Coefficients ◽  
Reliability Based Design ◽  
The Earth ◽  
Significant Probability

AbstractThe determination of the earth pressure coefficients (K) in geotechnical engineering is one of the most critical procedures in designing earth retaining walls. However, most earth pressure theories are made for either clay or sands, where the c-ϕ soils are the least analysed. In this paper, an analysis of the earth pressure for drained mixed soils based in Mazindrani and Ganjali (J Geotech Geoenviron Eng 123:110–112, 1997) theory was carried out. Earth pressure coefficients are generally used in a deterministic way and can represent designs under an inadmissible risk. Therefore, Reliability-based design arises as an essential tool to deal with soil variability as one of the main aspects of the geotechnical uncertainties. The influence of the soil variability in the active earth pressure for a c-ϕ soil was performed through probabilistic analysis concerning the Ka coefficient of variation (Cv) of both shear strength parameters. The sensitivity analysis shows a Cv in which the cohesion begins to have a more significant correlation with Ka than the friction angle. The results show an increase of the statistical Ka concerning the deterministic value as the soil variability and the soil slope (β) increase. Although the statistical value does not increase significantly, a statistical analysis on gravity walls and sheet pile walls in c-ϕ soils shows a significant probability of failure (pf) increase. The pf obtained through the c-ϕ variability can be considered inadmissible even if the required FS are met.

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