EFFECT OF WEATHERING ON DISINTEGRATION AND SHEAR STRENGTH REDUCTION OF CLAY SHALE

2016 ◽  
Vol 78 (7-3) ◽  
Author(s):  
Ramli Nazir ◽  
Idrus M Alatas ◽  
Samira A Kamaruddin ◽  
Masyhur Irsyam
Keyword(s):  
Shear Strength ◽  
Triaxial Tests ◽  
Shear Strength Parameters ◽  
Clay Shale ◽  
Clay Shales ◽  
Accelerate Weathering ◽  
Day Wetting ◽  
Range Of Values ◽  
Natural Drying ◽  
Shear Strength Reduction

Frequent and strong atmosphere and hydrosphere reactions accelerate weathering of clay shale. This study was carried out to determine the effects of frequent natural drying and wetting-drying cycles on clay shales in every 8 days until the value of disintegration ratio, DR reached zero (completely non-durable). Clay shale samples from Semarang-Bawen and Hambalang were tested in the laboratory under four circumstances: (1) without soaking, (2) soaked once in every 8 days, (3) soaked 2 times in every 8 day and (4) soaked 3 times in every 8 days. Disintegration ratio, DR was obtained from the change in grain size distribution of the clay shale due to weathering. Reductions in shear strength of the samples were observed after subjected to wetting-drying cycles. The DR of Semarang-Bawen clay shale reached zero after 32 days, while the DR of Hambalang clay shale showed a range of values between 0.09 and 0.147 on the 80th day. Wetting-drying cycles showed greater impact than natural drying on shear strength parameters reduction. Triaxial tests could only be performed on samples from Semarang-Bawen and Hambalang which were exposed to wetting-drying cycles up to 24 and 32 days of test, respectively beyond which the samples completely disintegrated.

scholarly journals UNDRAINED SHEAR STRENGTH PARAMETERS OF SAPROCK FROM A WEATHERING PROFILE OVER PORPHYRITIC BIOTITE GRANITE AT KM 31 OF THE KUALA LUMPUR - KARAK HIGHWAY, PENINSULAR MALAYSIA

2021 ◽  
Vol 33 (2) ◽  
Author(s):  
John Kuna Raj
Keyword(s):  
Shear Strength ◽  
Friction Angle ◽  
Undrained Shear Strength ◽  
Triaxial Tests ◽  
Regression Analyses ◽  
Shear Strength Parameters ◽  
Weathering Profile ◽  
Strength Parameters ◽  
Zone Ii ◽  
Undrained Shear

Three broad zones can be differentiated at the weathering profile; an upper, 9.4 m thick, pedological soil (zone I), an intermediate, 31.7 m thick, saprock (zone II) and the bottom bedrock (zone III). The saprock (zone II) comprises gravelly silty sands that distinctly preserve the minerals, textures and structures of the original granite and can be separated into sub-zones II A, II B, II C, and II D, based on differences in preservation of relict structures and content of litho-relicts (core-boulders). To characterize the undrained strength of saprock, samples were collected from sub-zones II A, II B, II C and II D and their physical and soil index properties determined before unconsolidated undrained triaxial tests were carried out on remolded samples. Three to four individual samples from each sub-zone were compressed under confining pressures of 138 kPa, 207 kPa, 276 kPa and/or 345 kPa. Plots of pf = [(σ1 + σ3)/2] versus qf = [(σ1 - σ3)/2] were then used to calculate apparent cohesions of 41.9 kPa, 100.3 kPa, 76.1 kPa and 73.9 kPa, and friction angles of 32.2o, 28.1o, 26.6o and 27.8o, for the samples from sub-zones II A, II B, II C, and II D, respectively. Regression analyses show apparent cohesions to decrease with increasing clay contents, and degrees of saturation; features indicating the influence of negative pore water (or suction) pressures. Regression analyses also show apparent friction angle to increase with increasing sand contents; a feature attributed to greater inter-locking and resistance to displacement of these particles. It is concluded that the undrained shear strength parameters of saprock are characterized by an average apparent cohesion of 54.6 kPa, and friction angle of 30.5o; the parameters influenced by the degree of saturation as well as clay and sand contents.

Behaviour of the stiff and sensitive Saint-Jean-Vianney clay in intact, destructured, and remoulded conditions

2002 ◽  
Vol 39 (5) ◽  
pp. 1075-1087 ◽  
Author(s):  
Faten Saihi ◽  
Serge Leroueil ◽  
Pierre La Rochelle ◽  
Ivan French
Keyword(s):  
Shear Strength ◽  
Large Deformation ◽  
Limit State ◽  
Triaxial Tests ◽  
Compression Tests ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Soft Clays ◽  
The Difference ◽  
State Curve

The role of the degree of microstructure on the behaviour of clayey soils has been the focus of many studies. However, none so far have quantified the evolution of the shear strength parameters for a given soil for degrees of microstructure going from an intact condition to complete remoulding. In the present study, a series of compression triaxial tests have been performed on specimens of the naturally highly structured Saint-Jean-Vianney clay under the following conditions: intact, destructured by straining outside the limit state curve, and reconstituted and reconsolidated after complete remoulding. The results show that the limit state curve is influenced by the level of destructuration reached before testing, and moreover, that the shear strength parameters at large deformation are influenced by the level of destructuration at the beginning of the test. The compression tests infer that the soil seems to retain the memory of its initial microstructure, at least for consolidation volumetric strains up to 14%. The observed behaviour has implications for the understanding and modelling of natural clays; it also explains to some extent the difference in strength parameters used in stability analyses of embankments on soft clays and natural slopes in clay.Key words: clay, microstructure, destructuration, shear strength, large deformation shear strength, triaxial test.

scholarly journals Application of the ANFIS to analysis of results from soil testings

2014 ◽  
Vol 13 (2) ◽  
pp. 007-015
Author(s):  
Ewa Daniszewska
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Fuzzy Model ◽  
Experimental Tests ◽  
Triaxial Tests ◽  
Physical Parameters ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Ground Sample ◽  
Neuro Fuzzy

The article was analyzed in order to test applicability and capability of the ANFIS tool used for interpretation of results of triaxial shear tests on loamy soils sampled near Olsztyn. The ANFIS system in the Matlab software programme was used to model and determine relationships between the shear stress and soil resistance parameters in a triaxial shear test apparatus. It has been demonstrated that the achieved shear strength parameters are significantly affected by the variables tested during the triaxial experiments and physical parameters of a given soil sample, but also by the loading increment rate during the tests. It is extremely important to adjust the rate of loading during a test according to the preliminary characterization of a tested ground sample so as to have some control over the obtained ground strength parameters. The neuro-fuzzy model has been constructed based on a set of values obtained after a series of experimental tests, including values of ground shear strength parameters. The database used for the neuro-fuzzy modelling consisted of 6 different ground parameters for each of the 12 shear stress rates applied during the triaxial tests. The learnability was verified on a database composed of the test results – a neuro-fuzzy model was built from learning sets and its accuracy was verified by sets of tests to which the model was applied for the first time. The results obtained from the ANFIS model did not diverge substantially from the ones obtained directly by performing the physical tests. The ANFIS proved to be highly universal and easy to operate. It accounted for the multi-faceted nature of interrelationships between ground parameters.

Stability of swelling clay embankments

1979 ◽  
Vol 16 (1) ◽  
pp. 140-151 ◽  
Author(s):  
R. A. Widger ◽  
D. G. Fredlund
Keyword(s):  
Shear Strength ◽  
Pore Water ◽  
Back Analysis ◽  
Triaxial Tests ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Total Strength ◽  
Swelling Soils ◽  
Pore Water Pressures ◽  
Matrix Suction

A common occurrence in cuts or fills of swelling soils is their reduction in strength with time. At the time of compaction, the clay generally has a high matrix suction. Correspondingly, it has a high strength and will stand at relatively steep side slopes. With time, the soil generally tends towards saturation and the matrix suction reduces towards zero. There is a reduction in total strength and if the gravitational forces are too large, the slope fails.During the past several years, numerous cut and fill slopes have been observed in the Regina area of Saskatchewan. Many of these slopes have remained stable for 4–6 years and then failed. There has been a 20 year history of observations on the Belle Plaine overpass west of Regina. Field and laboratory investigations have been conducted.With a knowledge of the geometry of the slope and failure plane, the simplified Bishop method of stability analysis was used to perform a 'back-analysis' to assess the shear strength parameters. The shear strength parameters from the laboratory program are compared with those calculated from the stability analyses. The analyses indicate that the peak shear strength parameters from triaxial tests on the softened Regina clay (i.e., c' = 5 kPa and [Formula: see text]), with the appropriate pore water pressures, give a factor of safety of 1 for the failed surface. The effect of spring thawing appears to be to produce the condition of most serious pore water pressures.

SHEAR STRENGTH DEGRADATION OF SEMARANG BAWEN CLAY SHALE DUE TO WEATHERING PROCESS

2015 ◽  
Vol 77 (11) ◽  
Author(s):  
Idrus M Alatas ◽  
Samira A Kamaruddin ◽  
Ramli Nazir ◽  
Masyhur Irsyam ◽  
Agus Himawan
Keyword(s):  
Shear Strength ◽  
Drying Process ◽  
Shear Strength Parameters ◽  
Stress Release ◽  
Strength Parameters ◽  
Residual Shear Strength ◽  
Clay Shale ◽  
Saturated Clay ◽  
Internal Angle ◽  
Weathering Process

The effect of weathering processes in decreasing the shear strength of clay shale had been done in this study. The drying process of clay shale with sunlight in the laboratory up to 80 days had been conducted to create the conditions of weathered sample. The peak and residual shear strength parameters of unsaturated and saturated clay shale were obtained from triaxial laboratory test, and all samples were tested on each 8 days of weathering process. Decrease of shear strength in peak and residual condition was obtained during 80 days of the drying process. The residual shear strength parameters were distinguished between residual shear strength without stress release and with stress release of confining pressure. The results up to 80 days of unsaturated clay shale showed that the cohesion at peak stress conditions reduced to 30 % based on initial shear strength before the occurrence weathering, while the internal angle friction reduced to 64 %. Residual cohesion without and with stress release reduced to 4 % and 1 %, respectively while residual internal angle friction without and with stress release reduced to 15 % and 5 %. Similar situation also occurs for the saturated clay shale samples.

scholarly journals Experimental Investigation on Shear Strength Parameters of Lime Stabilized Loess

2019 ◽  
Vol 11 (19) ◽  
pp. 5397 ◽  
Author(s):  
Liang Jia ◽  
Jian Guo ◽  
Yanbin Jiang ◽  
Yong Fu ◽  
Zhidong Zhou ◽  
...  
Keyword(s):  
Shear Strength ◽  
Yellow River ◽  
Friction Angle ◽  
Experimental Results ◽  
Triaxial Tests ◽  
Curing Time ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Lime Content ◽  
Coulomb Failure

Loess is a typical collapsible soil, which is widely distributed in the upper and middle areas around the Yellow River of China. The stabilization of loess with lime provides a significant improvement in the physical and the mechanical characteristics of the loess and is therefore widely used in the pavement base and subgrade. Therefore, a systematic investigation of Mohr-Coulomb failure envelope of lime stabilized loess needs to be conducted. In this pursuit, the present research envisages the investigation of the effects of the lime content, porosity and curing time on the strength parameters (friction angle (φ) and cohesion (c)), using a series of triaxial tests performed on lime stabilized loess specimens. The experimental results revealed that the friction angle (φ) was independent of the lime content, the porosity and the curing time of the specimen for a given lime stabilized loess, while the factors mentioned above had a significant effect on the cohesion (c) of the lime stabilized loess. For a relatively short curing time (7 days), the change in the lime content did not present an obvious effect on the cohesion (c) of the stabilized loess. However, when the curing time (28, 90 and 180 days) was longer, the increase of the lime content significantly enhanced the cohesion of the stabilized loess. When the lime content was constant, the cohesion (c) of the stabilized loess increased linearly with the decrease in the void ratio. A power function equation was proposed to assess the comprehensive influences of the factors like the lime content, porosity and curing time on cohesion (c). Finally, the Mohr-Coulomb failure envelopes were drawn based on the triaxial test for 47 specimens with various curing time and confining pressure, and the shear strength parameters obtained by the proposed equation were also compared with the experimental results.

Using Excel to Evaluate Shear Strength Parameters of Soil

2013 ◽  
Vol 709 ◽  
pp. 579-582
Author(s):  
Meng Hua Fan
Keyword(s):  
Shear Strength ◽  
Shear Test ◽  
Triaxial Tests ◽  
Mathematics Model ◽  
Direct Shear ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Direct Shear Tests ◽  
Allowable Deviation ◽  
Coulomb Failure

It is difficult to determine the Mohr-Coulomb failure envelope visually, and it is strongly influenced by abnormal test data evaluating the shear strength parameters of soil via trend line and unable to adjust the scope of permissible error. So it is recommended to evaluate shear strength parameters of soil using Solver of Excel for direct shear tests and triaxial tests and you can control the allowable deviation. The mathematics model of nonlinear programming was established to evaluate shear strength parameters of soil from the results of direct shear test and triaxial shear test. The related Excel worksheet was created and the optimum results of the objective function were obtained by setting the Solver parameters dialog box accurately. The method is simple, inexpensive and rapid.

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