Large Scale Laboratory Tests of the Shear Strength of Rocky Material

1964 ◽  
pp. 20-30 ◽  
Author(s):  
D. Krsmanović ◽  
Z. Langof
Keyword(s):  
Shear Strength ◽  
Laboratory Tests ◽  
Large Scale

scholarly journals Evaluation of temporal, seasonal and geographic stability of the molluscicidal property of Euphorbia splendens latex

1992 ◽  
Vol 34 (3) ◽  
pp. 183-191 ◽  
Author(s):  
Virginia Torres Schall ◽  
Mauricio Carvalho de Vasconcellos ◽  
Ana Luiza Villaça-Coelho ◽  
Fátima Eliana Ferreira-Lopes ◽  
Ivonise Paz da Silva
Keyword(s):  
Aqueous Solutions ◽  
Laboratory Tests ◽  
Large Scale ◽  
Room Temperature ◽  
Tropical Climate ◽  
Wide Distribution ◽  
Promising Material ◽  
Active Principle ◽  
Reference Substance ◽  
Belo Horizonte

Laboratory tests with aqueous solutions of Euphorbia splendens var. hislopii latex have demonstrated seasonal stability of the molluscicidal principle, with LD90 values of 1.14 ppm (spring), 1.02 ppm (fall), 1.09 ppm (winter), and 1.07 ppm (summer) that have been determined against Biomphalaria tenagophila in the field. Assays on latex collected in Belo Horizonte and Recife yielded LD90 values similar to those obtained with the reference substance collected in Rio de Janeiro (Ilha do Governador), demonstrating geographic stability of the molluscicidal effect. The molluscicidal action of aqueous dilutions of the latex in natura, centrifuged (precipitate) and lyophilized, was stable for up to 124 days at room temperature (in natura) and for up to 736 days in a common refrigerator at 10 to 12ºC (lyophilized product). A 5.0 ppm solution is 100% lethal for snails up to 13 days after preparation, the effect being gradually lost to almost total inactivity by the 30th day. This observation indicated that the active principle is instable. These properties together with the wide distribution of the plant, its resistance and adaptation to the tropical climate, its easy cultivation and the easy obtention of latex and preparation of the molluscicidal solution, make this a promising material for large-scale use in the control of schistosomiasis

scholarly journals Basic Mechanical Parameter Relations of Soft Clay in Pearl River Delta

2014 ◽  
Vol 8 (1) ◽  
pp. 320-325 ◽  
Author(s):  
Zhangming Li ◽  
Na Qi ◽  
Zhibin Masumi ◽  
Weidi Lin
Keyword(s):  
Shear Strength ◽  
Pearl River Delta ◽  
Large Scale ◽  
Soft Clay ◽  
River Delta ◽  
Pearl River ◽  
Cylindrical Cavity Expansion ◽  
In Situ Data ◽  
The Pearl River

Basic parameters relations among CPT parameters, un-drained strength and other mechanical parameters of soft clay are presented based on an elastic-plastic solution for cylindrical cavity expansion for soil investigation in energy engineering. The relation between CPT parameters and shear strength from vane test is also presented based on the result. Thus, the CPT parameters can be determined directly by elastic parameters and shear strength or vane shear parameters and vice versa. That makes it possible to save the high test costs and provide theoretical formulas to avoid some tests which are limited due to the site and/or other condition. Results are compared between the relations and in situ data at a large-scale project in the Pearl River Delta. The results showed consistency between the relation and in situ data.

scholarly journals Influence of Maximum Particle Diameter on the Mechanical Behavior of Soil-Rock Mixtures

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Zhuoling He ◽  
Junyun Zhang ◽  
Tao Sun
Keyword(s):  
Shear Strength ◽  
Large Scale ◽  
Direct Shear Test ◽  
Shear Test ◽  
Particle Diameter ◽  
Size Difference ◽  
Direct Shear ◽  
Fine Grained ◽  
Fine Grained Soil ◽  
Maximum Particle

With the steady development of the development of the western region in China, the construction of mountain highways has developed rapidly, and the soil-rock mixed filler, as an excellent filler, is widely used in the subgrade filling of mountain highways. Unlike ordinary fine-grained soil, the source of the soil-rock mixtures (S-RMs) is not unique, and the particle size difference is large and the water content is not uniform, resulting in very complicated mechanical properties. But the current highway embankment codes are still mainly established on the fine-grained soil. It is not fully applicable to soil-rock filled embankment. Based on soil-rock filled embankment engineering practice, this research uses a large-scale direct shear test to research the mechanical characteristics of the S-RMs with different maximum particle diameters. According to the large-scale direct shear test of S-RMs with different maximum particle diameters, the shear displacement vs shear stress curve, shear dilation, and strength characteristics with maximum particle diameter were analyzed. Results demonstrate that whether secondary hardening occurs mainly depends on the normal stress and the maximum particle diameter of the filler. At different maximum particle diameters, the horizontal displacement vs vertical displacement curves of the S-RMs can be roughly divided into continuous shearing and beginning of shearing and quick dilation. And the shear strength increases with the increase of the maximum particle diameter. Moreover, the cohesion decreases first and then increases with the increase of the maximum particle diameter, and the internal friction angle increases with the increase of the maximum particle diameter. Therefore, some RBs with large particle diameter added to filler can effectively improve the shear strength of the S-RMs, which may be valuable for realistic engineering.

Shear Strength of Sand–Clay Interfaces Through Large-Scale Direct Shear Tests

2020 ◽  
Vol 45 (5) ◽  
pp. 4343-4357
Author(s):  
Zhong-Liang Zhang ◽  
Zhen-Dong Cui ◽  
Ling-Zi Zhao
Keyword(s):  
Shear Strength ◽  
Large Scale ◽  
Direct Shear ◽  
Shear Tests ◽  
Direct Shear Tests

scholarly journals Determining the Shear Strength Properties of a Soil-geogrid Interface Using a Large-scale Direct Shear Test Apparatus

2020 ◽  
Author(s):  
Jakub Stacho ◽  
Monika Sulovska ◽  
Ivan Slavik
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Large Scale ◽  
Direct Shear Test ◽  
Shear Test ◽  
Strength Properties ◽  
Coarse Grained ◽  
Direct Shear ◽  
Test Apparatus ◽  
Fine Gravel

The paper deals with the laboratory testing of coarse-grained soils that are reinforced using a geogrid. The shear strength properties were determined using a large-scale direct shear test apparatus. The tests were executed on original as well as on reinforced soil, when the geogrid was placed on a sliding surface, which permitted determining the shear strength properties of the soil-geogrid interface. The aim of the tests was to determine the interface shear strength coefficient α, which represents the ratio of the shear strength of the soil-geogrid interface to the unreinforced soil. The tests were executed on 3 samples of coarse-grained materials, i.e., poorly graded sand, poorly graded fine gravel and poorly graded medium gravel. Two types of geogrids were tested, i.e., a woven polyester geogrid and a stiff polypropylene geogrid. The results of the laboratory tests on the medium gravel showed that the reduction coefficient α reached higher values in the case of the stiff polypropylene geogrid. In the cases of the fine gravel and sand, the values of the interface coefficient α were similar to each other. The shear strength of the interface was reduced or was similar to the shear strength of unreinforced soil in a peak shear stress state, but significantly increased with horizontal deformations, especially for the fine gravel and sand. The largest value of the coefficient α was measured in the critical shear stress state. Based on the results of the testing, a correlation which allows for determining the optimal grain size distribution was obtained.

Moisture Effects on Degraded Ballast Shear Strength Behavior

2016 ◽  
Author(s):  
Yu Qian ◽  
Debakanta Mishra ◽  
Erol Tutumluer ◽  
Youssef M. A. Hashash ◽  
Jamshid Ghaboussi
Keyword(s):  
Shear Strength ◽  
Los Angeles ◽  
Large Scale ◽  
Coal Dust ◽  
Axial Strain ◽  
Dust Collection ◽  
Uniform Size ◽  
Classical Text ◽  
Fouled Ballast ◽  
Strength Behavior

Ballast consisting of large sized aggregate particles with uniform size distribution is an essential component of the track substructure, to facilitate load distribution and drainage. As freight tonnage accumulates with traffic, ballast will accumulate an increasing percentage of fines due to either aggregate breakdown or outside contamination such as subgrade soil intrusion and coal dust collection. According to the classical text by Selig and Waters [1], ballast degradation from traffic involves up to 76% of all fouling cases; voids will be occupied by fines from the bottom of ballast layer gradually causing ballast clogging and losing its drainage ability. When moisture is trapped within ballast, especially fouled ballast, ballast layer stability is compromised. In the recent studies at the University of Illinois, the focus has been to evaluate behavior of fouled ballast due to aggregate degradation using large scale triaxial testing. To investigate the effects of moisture on degraded ballast, fouled ballast was generated in the laboratory through controlled Los Angeles (LA) abrasion tests intended to mimic aggregate abrasion and breakdown and generate fouled ballast at compositions similar to those observed in the field due to repeated train loadings. Triaxial shear strength tests were performed on the fouled ballast at different moisture contents. Important findings of this preliminary study on characterizing wet fouled ballast are presented in this paper. Moisture was found to have a significant effect on the fouled ballast strength behavior. Adding a small amount of 3% moisture (by weight of particles smaller than 3/8 in. size or smaller than 9.5 mm) caused test specimens to indicate approximately 50% decrease in shear strength of the dry fouled ballast. Wet fouled ballast samples peaked at significantly lower maximum deviator stress values at relatively smaller axial strains and remained at these low levels as the axial strain was increased.

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