Strength of tree roots and landslides on Prince of Wales Island, Alaska

1979 ◽  
Vol 16 (1) ◽  
pp. 19-33 ◽  
Author(s):  
Tien H. Wu ◽  
William P. McKinnell III ◽  
Douglas N. Swanston
Keyword(s):  
Shear Strength ◽  
Root System ◽  
Forest Cover ◽  
Safety Factors ◽  
In Situ Tests ◽  
Tree Roots ◽  
Stability Of Slopes ◽  
Before And After ◽  
The Stability

The stability of slopes before and after removal of forest cover was investigated. Porewater pressures and shear strengths were measured and the soil properties were determined by laboratory and in situ tests. A model of the soil–root system was developed to evaluate the contribution of tree roots to shear strength. The computed safety factors are in general agreement with observed behaviors of the slopes. Decay of tree roots subsequent to logging was found to cause a reduction in the shear strength of the soil–root system.

scholarly journals A Copula-Based Method for Estimating Shear Strength Parameters of Rock Mass

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Da Huang ◽  
Chao Yang ◽  
Bin Zeng ◽  
Guoyang Fu
Keyword(s):  
Shear Strength ◽  
Rock Mass ◽  
Probabilistic Method ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Copula Functions ◽  
In Situ Tests ◽  
Underground Caverns ◽  
The Stability

The shear strength parameters (i.e., the internal friction coefficientfand cohesionc) are very important in rock engineering, especially for the stability analysis and reinforcement design of slopes and underground caverns. In this paper, a probabilistic method, Copula-based method, is proposed for estimating the shear strength parameters of rock mass. The optimal Copula functions between rock mass qualityQandf,Qandcfor the marbles are established based on the correlation analyses of the results of 12 sets of in situ tests in the exploration adits of Jinping I-Stage Hydropower Station. Although the Copula functions are derived from the in situ tests for the marbles, they can be extended to be applied to other types of rock mass with similar geological and mechanical properties. For another 9 sets of in situ tests as an extensional application, by comparison with the results from Hoek-Brown criterion, the estimated values offandcfrom the Copula-based method achieve better accuracy. Therefore, the proposed Copula-based method is an effective tool in estimating rock strength parameters.

scholarly journals Strength Theory Model of Unsaturated Soils with Suction Stress Concept

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Pan Chen ◽  
Changfu Wei ◽  
Jie Liu ◽  
Tiantian Ma
Keyword(s):  
Shear Strength ◽  
Unsaturated Soils ◽  
Theory Model ◽  
Strength Analysis ◽  
New Model ◽  
Suction Stress ◽  
Strength Change ◽  
Stability Of Slopes ◽  
Moisture State ◽  
The Stability

A theoretical model is developed for describing the strength property of unsaturated soils. The model is able to predict conveniently the strength changes of unsaturated soils undergoing repeated changes of water content. Suction stress is adopted in the new model in order to get the sound form of effective stress for unsaturated soils. The shear strength of unsaturated soils is dependent on its soil-moisture state based on the results of shear experiments. Hence, the parameters of this model are related tightly to hydraulic properties of unsaturated soils and the strength parameters of saturated soils. The predictive curves by the new model are coincident with experimental data that underwent single drying and drying/wetting cycle paths. Hence, hysteretic effect in the strength analysis is necessary to be considered to predict the change of shear strength of unsaturated soils that underwent drying/wetting cycles. Once the new model is used to predict the change of shear strength, lots of time could be saved due to avoiding heavy and complicated strength tests of unsaturated soils. Especially, the model can be suitable to evaluate the shear strength change of unsaturated soils and the stability of slopes experienced the drying/wetting cycles.

In Situ Shear Tests on Masonry Panels Strengthened with Fiber-Reinforced Mortar Repointing

2017 ◽  
Vol 747 ◽  
pp. 282-288
Author(s):  
Nicola Cavalagli ◽  
Massimiliano Gioffrè ◽  
Vittorio Gusella ◽  
Chiara Pepi ◽  
Bernie Baietti ◽  
...  
Keyword(s):  
Shear Strength ◽  
Local Information ◽  
Fiber Reinforced ◽  
Compression Tests ◽  
Shear Tests ◽  
In Situ Tests ◽  
Joint Shear Strength ◽  
Reinforced Masonry ◽  
Diagonal Compression

In this paper the effect of joints structural repointing on single-wythe brickwork masonry using a fiber-reinforced mortar is investigated. Changes in shear strength are evaluated by in-situ tests carried out both on unreinforced and reinforced masonry specimens. The masonry joint shear strength, according to the standard ASTM C 1513, gives local information, while diagonal compression tests provides information on the global masonry shear response. The comparison highlights a good performance in both local and global masonry response, where the shear strength increases.

In situ shear tests of soil blocks with roots

1998 ◽  
Vol 35 (4) ◽  
pp. 579-590 ◽  
Author(s):  
Tien H Wu ◽  
Alex Watson
Keyword(s):  
Shear Strength ◽  
Root System ◽  
Tensile Force ◽  
Failure Surface ◽  
Soil Reinforcement ◽  
Shear Tests ◽  
Maximum Displacement ◽  
Shearing Resistance ◽  
Simplified Procedures

In situ shear tests were performed on soil blocks that contained roots to study the contribution of roots to the shear strength in a case where the shear deformation is not constrained to a thin zone. The shearing resistance of the soil-root system, the tensile force in selected roots, and the deformation of the soil block were measured. The roots were exposed after the test and their positions were determined and used to estimate the initial positions. The root force and the shearing resistance of the soil-root system were estimated with known solutions and compared with measured root force and shearing resistance. None of the roots that passed through the shear zone failed in tension at the maximum displacement. As a consequence, the root resistance is much less than that found in a case where the failure surface is restricted to the boundary between a weak soil and a firm base and where roots are anchored in the firm base and fail in tension. Simplified procedures for estimating root forces are suggested for the case of a thick shear zone.Key words: in situ test, roots, shear strength, slope stability, soil reinforcement, soil–root interaction.

Liquefaction performance of soils at the site of a partially completed ground improvement project during the 1999 Chi-Chi earthquake in Taiwan

2001 ◽  
Vol 38 (6) ◽  
pp. 1241-1253 ◽  
Author(s):  
Der-Her Lee ◽  
C Hsein Juang ◽  
Chi-Sheng Ku
Keyword(s):  
Ground Improvement ◽  
Construction Site ◽  
Cone Penetration ◽  
In Situ Tests ◽  
Improvement Project ◽  
Cone Penetration Tests ◽  
Hydraulic Filling ◽  
Before And After ◽  
Penetration Tests

This paper examines the liquefaction performance of soils at the site of a partially completed ground improvement project at the Chang-Hwa Coastal Industrial Park during the 1999 Chi-Chi earthquake in Taiwan. The site is on land reclaimed by hydraulic filling. To meet the need of a planned construction, site characterization was carried out with standard penetration tests (SPTs) and cone penetration tests (CPTs) at 13 locations. Dynamic compaction was later performed to mitigate the potential liquefaction hazards at this site. Before completion of the ground improvement work, the site experienced a major earthquake, the Chi-Chi earthquake (magnitude Mw = 7.6). Evidence of liquefaction was observed in this earthquake in the unimproved area but not in the improved area. After the earthquake, additional site exploration was carried out using SPTs and CPTs. The data from these in situ tests carried out before and after the earthquake and in areas with and without ground improvement are analyzed and the results are reported.Key words: ground improvement, in situ tests, liquefaction, earthquake.

scholarly journals Parametric evaluation of shear strength parameters on the stability of cut slope: a case study from Mahabaleshwar road section, India

2016 ◽  
Vol 51 ◽  
pp. 73-76
Author(s):  
Suman Panthee
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Shear Strength ◽  
Internal Friction ◽  
Factor Of Safety ◽  
Slope Failure ◽  
Cut Slope ◽  
Stability Of Slopes ◽  
Proportional Relation ◽  
The Stability

Stability of rock cut slopes depends upon the type of material, discontinuity attributes and geometry present in any location. Although, gravity remains the constant important factor in dictating the slope failure but other parameters like shear strength and available shear stress along the slope also decides the stability of the slopes to great extent. The strength of the material comes from the internal bonding between the mineral grains, contact between the particles and the ability of the material to respond to the stress conditions. Variation of these material attributes fluctuate the cohesion and angle of internal friction that constitutes the most important properties in defining the strength of any material. Rock resists shear stress by these two internal mechanisms. Numerical simulation by Finite Element Method technique is attempted for assessing the stability cut slope. An attempt has been made in this study to document the behavior of strength of the material in terms of stability of slopes by parametric study of cohesion and internal friction. This study carried to understand how the factor of safety changes with reference to change in cut slope height, cohesion and internal friction of the discontinuities that attributes the shear strength of discontinuities. The study is based on Finite Element Modeling (FEM). From the study it is found that factor of safety has strongly proportional relation with cohesion and internal friction but shown inversely proportional relation with height of cut slope.

On the evaluation of undrained shear strength and preconsolidation pressure from common field tests in clay

2005 ◽  
Vol 42 (4) ◽  
pp. 1221-1231 ◽  
Author(s):  
Rolf Larsson ◽  
Helen Åhnberg
Keyword(s):  
Shear Strength ◽  
Soft Clay ◽  
Field Tests ◽  
Undrained Shear Strength ◽  
Test Field ◽  
Cone Penetration ◽  
In Situ Tests ◽  
Cone Penetration Tests ◽  
The Stability ◽  
Undrained Shear

The undrained shear strength is a key parameter in the estimation of the stability of natural slopes and man-made constructions in soft clay. It is therefore important to develop relevant methods to evaluate the operative strength. Results from an investigation regarding the effect of excavations at slope crests to increase the stability of clay slopes are presented. This study has provided an opportunity to study the effect of overconsolidation on the evaluated parameters from common in situ tests in homogeneous and truly overconsolidated clays. Certain inconsistencies in the commonly used methods of interpretation of field vane tests, cone penetration tests, and dilatometer tests are highlighted, and modified interpretation methods taking the effects of overconsolidation into account are proposed.Key words: clay, overconsolidation, undrained shear strength, cone penetration test, field vane test, dilatometer test.

Bearing capacity under cyclic loading — offshore, along the coast, and on land. The 21st Bjerrum Lecture presented in Oslo, 23 November 2007This paper represents the written version of the 21st Bjerrum Lecture. While it has been edited for the present publication, it retains the general structure of the original lecture, which was intended for a general geotechnical audience. The Bjerrum Lecture is presented in Oslo in alternate years by the Norwegian Geotechnical Society with the support of the Bjerrum Memorial Fund (Laurits Bjerrums Minnefond).

2009 ◽  
Vol 46 (5) ◽  
pp. 513-535 ◽  
Author(s):  
Knut H. Andersen
Keyword(s):  
Shear Strength ◽  
Cyclic Loading ◽  
General Structure ◽  
Stress Path ◽  
Shear Stresses ◽  
Foundation Design ◽  
Cyclic Shear ◽  
Stability Of Slopes ◽  
Practical Design ◽  
The Stability

Cyclic loading can be important for the foundation design of structures, both offshore, along the coast, and on land, and for the stability of slopes. This is illustrated by several examples. The paper discusses how soil behaves under cyclic loading, both for structures and for slopes, and shows that the cyclic shear strength and the failure mode under cyclic loading depend strongly on the stress path and the combination of average and cyclic shear stresses. Diagrams with the cyclic shear strength of clay, sand, and silt that can be used in practical design are presented. Comparisons between calculations and model tests indicate that foundation capacity under cyclic loading can be determined on the basis of cyclic shear strength determined in laboratory tests.

Sign in / Sign up

Export Citation Format

Share Document