Shear Strength Of Rockfill Research Articles

Experimental Study of Rockfill Particle Breakage

As the high concrete faced rockfill dams construction, grain breakage gradually become the factors that influence the high dam construction which can not be ignored. This text based on the master of rockfill of shuibuya dam as the experimental material, getting and analyzing the particle breakage data under different confining pressure through the large-scale triaxial test, and the results show that the particle breakage index increases with the increase of confining pressures. The relationship between particle breakage index and confining pressure can be expressed by formula;Particle breakage increase leading to reduced internal friction angle and the shear strength of rockfill, and the author newly introduced two broken variable to describe the relationship which can be expressed by the formula between the particle breakage and internal friction angle, it has certain reference value for establishing constitutive model considering particle breakage.

A large triaxial investigation of the stress-path-dependent behavior of compacted rockfill

Realistic prediction of the deformation of rockfill structures becomes increasingly important, which requires improved knowledge about the mechanical properties of rockfill materials. However, previous large triaxial tests were usually carried out with a constant cell pressure, and there is uncertainty about the behavior of rockfill along other stress paths. This paper presents the results of a series of large triaxial tests conducted on limestone rockfill specimens along different loading paths. The effect of previous loading history and moisture content has also been investigated. The results show that the stress–strain and volumetric behavior of rockfill are significantly influenced by the loading directions as well as the confining pressures. However, the stress path appears to have only minor influence on the shear strength of rockfill, while the strength envelope exhibits pronounced curvature at low confining pressures and the peak friction angle decreases approximately linearly with the logarithm of the corresponding confining pressure. The previous loading history is revealed to have considerable effect on the stress–strain behavior but small influence on the peak strength of rockfill. In contrast, the moisture content of rockfill has marked influence on both the deformation and the strength characteristics. The implications of the test results are discussed.

Analysis of Earth-Rockfill Dam Slope Stability by Strength Reduction Method Based on Nonlinear Strength

In the design process of the earth-rock dam, the slope stability problem was always focused on. The shear strength of rockfill in the earth-rock dam had strong nonlinear characteristics. The characteristic directly affected the factor of safety (FOS) of stability of dam slope and the determination of the critical slip surface. The shear strength parameter of rockfill was related to the minimum principal stress σ3 closely. And the value of σ3 had close relationship with the deformation characteristics of filling material and the process of dam filling etc. Strength reduction method has been widely used in solving the FOS of slope stability, and this method has the advantage on the searching of the critical slip surface. Combining the deformation and stress analysis of earth-rockfill dam filling process and the strength reduction method, this paper proposes a comprehensive method of dam slope stability analysis.

Large-scale triaxial testing of grey wacke rockfill

This Paper describes the results of a series of large-scale triaxial tests conducted on greywacke rockfill, used in dam construction in Southern Thailand. The tests are conducted at low to moderate confining stresses to relate their findings to the stability of rockfill dams. Considering the current test results in conjunction with previous laboratory data, revised failure criteria for rockfill are proposed in non-dimensional form. For both low and high confining stresses, lower and upper bounds of strength envelopes have been established, based on a wide array of granular materials. The influence of the confining stress on the shear strength of rockfill is studied in depth, and the implications of a non-linear envelope at low normal stress levels on the stability of rockfill dams are discussed. Although two parallel rockfill gradations for specimens compacted to similar porosities are considered, the exact role of particle size effect on shear strength is not examined in detail, as the difference in maximum particle sizes tested in this study is not sufficiently large. Cet article décrit les résultats d'une suite d'essais au triaxial à grande échelle réalisés sur du remblai rocheux (greywacke) utilisé pour la construction de barrages dans le sud de la Thaïlande. Ces essais sont exécutés à des pressions de cellule faibles à modérées pour rapprocher les résultats de la stabilité de barrages à enrochement. En considérant les résultats existant d'essais, en conjonction avec les données de laboratoire précédentes, des critères de rupture de l'enrochement sont proposés dans une forme sans dimensions. Pour des pressions de cellule faibles et élevées, les enveloppes basses et hautes de résistance ont été établies, basées sur un vaste ensemble de matériaux granuleux. L'influence de la pression de cellule sur la résistance au cisaillement est étudiée en profondeur et les conséquences d'une enveloppe de rupture non linéaire à containtes normales faibles sur la stabilité de barrages à enrochement sont discutées. Bien que deux gradations parallèles d'enrochement pour des échantillons compactés à des porosités semblables aient été considérées, le rôle exact de l'effet de la taille des grains sur la résistance au cisaillement n'est pas examiné en détails car la différence entre les tailles maxis des grains testés pour cette étude n'était pas suffisante.

Shear strength of rockfill : Barton, N; Kjaernsli, B J Geotech Engng Div ASCE, V107, NGT7, July 1981, P873–891

Shear testing of rockfill is an important problem which raises unique difficulties, owing to the size of the rock lumps compared with the size of conventional testing apparatus. Very little information has been published, and there is scope for determined research in this field.

In-situ shear test for rock fills : 12F, 4T, 10R. J. Geotech. Engng. Div. V100, GT9, Sept. 1974, P1031–1050

Large-scale in-situ shear tests were devised to determine the shear strength of soft rock and broken rockfill. A steel hollow box is sunk into rockfill to obtain an in-situ specimen for testing shear planes 2 or 4 ft (0.6 or 1.2 m) square. The shear strength of rockfills was found higher than that of the -3/16-in. (4.8-mm) fraction when compacted to attain the same void ratio. The ratio of creep strength to shearing resistance of the compacted crushed clay shale (of low plasticity) was determined to be 0.4. The value of coefficient of friction between stratified crushed clay shale fill layers decreased with an increase of normal pressure in a straight-line relationship. When the minimum ratio of 5:1 between the size of specimen and rock particles is not kept and there are large rock particles present, laboratory tests demonstrate the alteration in paths of shear cracks in compressive strength tests.

In-Situ Shear Test for Rock Fills

Large-scale in-situ shear tests were devised to determine the shear strength of soft rock and broken rockfill. A steel hollow box is sunk into rockfill to obtain an in-situ specimen for testing shear planes 2 or 4 ft (0.6 or 1.2 m) square. The shear strength of rockfills was found higher than that of the -3/16-in. (4.8-mm) fraction when compacted to attain the same void ratio. The ratio of creep strength to shearing resistance of the compacted crushed clay shale (of low plasticity) was determined to be 0.4. The value of coefficient of friction between stratified crushed clay shale fill layers decreased with an increase of normal pressure in a straight-line relationship. When the minimum ratio of 5:1 between the size of specimen and rock particles is not kept and there are large rock particles present, laboratory tests demonstrate the alteration in paths of shear cracks in compressive strength tests.

A theory for the shear strength of rockfill

A Theory for the Shear Strength of Rockfill Existing knowledge of the meaning of the shear strength of rock fill, and of how and why it varies is inadequate. Shear strength is shown to be controlled by the basic angle of friction of rock on rock (Φu), the voids ratio (e) and the particle breakage (B) and to be dependent on the ratio of major to minor principal stresses. Using statistical methods combined with some simple assumptions based on experimental work formulas are derived for the shear strength of rock fill. Theoretical results are compared with the results of laboratory triaxial tests.