Effect of Specimens’ Height to Diameter Ratio on Unconfined Compressive Strength of Cohesive Soil

Haile Tsegay Gebresamuel; Damtew Tsige Melese; Yada Tesfaye Boru; Alemu Mosisa Legese

Open Access

Effect of Specimens’ Height to Diameter Ratio on Unconfined Compressive Strength of Cohesive Soil

Haile Tsegay Gebresamuel

Damtew Tsige Melese

Yada Tesfaye Boru

and

Alemu Mosisa Legese

| Mar 09, 2023

Studia Geotechnica et Mechanica

Volume 45 (2023): Issue 2 (June 2023)

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Cite

Published Online: Mar 09, 2023

Page range: 112 - 132

Received: Jun 05, 2022

Accepted: Nov 29, 2022

DOI: https://doi.org/10.2478/sgem-2023-0001

Keywords
Height to diameter ratio, Unconfined compression strength, UCS scale effect

© 2023 Haile Tsegay Gebresamuel et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Graph of standard Proctor compaction curves.

Peak value of unconfined compressive strength for specimens with diameter of 38, 50, and 100 mm with their respective H/D ratio.

Percentage of UCS difference from the mean value for 38, 50, and 100 mm specimen diameters.

Stress–strain curves for 38 mm, 50 mm, and 100 mm specimen diameters of Ajip test pit from top to bottom.

Stress–strain curves for 38 mm, 50 mm, and 100 mm specimen diameters of Aweytu test pit from top to bottom.

Stress–strain curves for 38 mm, 50 mm, and 100 mm specimen diameters of JIT campus test pit from top to bottom.

Stress–strain curves for 38 mm, 50 mm, and 100 mm specimen diameters of Mariam Church test pit from top to bottom.

Stress–strain curves for 38 mm, 50 mm, and 100 mm specimen diameters of Saris Sefer test pit from top to bottom.

Failure pattern of 38 mm specimen diameter: (a) Ajip, (b) Aweytu, (c) JIT campus, (d) Saris Sefer, and (e) Mariam Church.

Failure pattern of 50 mm specimen diameter: (a) Ajip, (b) Aweytu, (c) JIT campus, (d) Saris Sefer, and (e) Mariam Church.

Failure pattern of 100 mm specimen diameter: (a) Saris Sefer and (b) Mariam Church.

Failure pattern of 100 mm specimen diameter: (a) Ajip, (b) Aweytu, (c) JIT campus.

The scatter plot of UCS versus H/D ratio for 38, 50, and 100 mm specimen diameter from left to right.

Plot of UCS/UCS2.00 versus height to diameter ratio for a specimen diameter of 38 mm.

The plot of UCS/UCS2.00 versus height to diameter ratio of 50 mm specimen diameter.

The plot of UCS/UCS2.00 versus height to diameter ratio of 100 mm specimen diameter.

Model summary of UCS/(UCS at 2 H/D ratios)-50 mm diameter and H/D ratio.

Model summary^b

Model	R	R²	Adjusted R²	Std error of the estimate
2	0.969^a	0.938	0.937	0.0540444

Descriptive statistics of the peak UCS value for specimens of diameter 50 mm.

	Number of observations	Minimum (kPa)	Maximum (kPa)	Mean (kPa)	Std deviation	Skewness	Skewness std error	Kurtosis	Kurtosis std error
Mariam Church	9	196.73	321.97	254.91	41.74	0.132	0.717	−0.909	1.400
Ajip	9	245.42	503.90	358.01	79.63	0.529	0.717	0.005	1.400
Aweytu	9	203.80	396.40	285.28	62.33	0.627	0.717	−0.180	1.400
Saris Sefer	9	174.75	391.34	272.07	71.92	0.313	0.717	−0.757	1.400
JIT campus	9	292.35	546.82	401.37	85.46	0.525	0.717	−0.755	1.400

Descriptive statistics of the peak UCS value for specimens of diameter 38 mm.

	Number of observations	Minimum (kPa)	Maximum (kPa)	Mean (kPa)	Std deviation	Skewness	Skewness std error	Kurtosis	Kurtosis std error
Mariam Church	9	200.54	348.63	271.96	42.55	0.177	0.717	0.649	1.400
Ajip	9	299.33	525.21	395.97	71.13	0.527	0.717	−0.046	1.400
Aweytu	9	238.07	474.49	332.04	75.12	0.776	0.717	0.114	1.400
Saris Sefer	9	206.53	428.74	307.54	68.45	0.308	0.717	−0.111	1.400
JIT campus	9	397.37	728.32	528.64	108.76	0.682	0.717	−0.293	1.400

Shapiro–Wilk normality test.

	38 mm specimen diameter			50 mm specimen diameter			100 mm specimen diameter

	Statistic	Degrees of freedom	Sig.	Statistic	Degrees of freedom	Sig.	Statistic	Degrees of freedom	Sig.
Mariam Church	0.989	9	0.995	0.974	9	0.926	0.968	9	0.879
Ajip	0.974	9	0.925	0.977	9	0.946	0.936	9	0.538
Aweytu	0.952	9	0.709	0.956	9	0.759	0.959	9	0.784
Saris Sefer	0.988	9	0.994	0.974	9	0.925	0.935	9	0.532
JIT campus	0.953	9	0.725	0.958	9	0.776	0.981	9	0.969

Significance level (Sig.) and Pearson correlation coefficient (R) of UCS value for 100 mm specimen diameter.

		Height to diameter ratio	UCS of Mariam Church test pit	UCS of Ajip test pit	UCS of Aweytu test pit	UCS of Saris Sefer	UCS of JIT campus test pit
Height to diameter ratio (H/D)	R	1	−0.979	−0.988	−0.992	−0.987	−0.990
	Sig.		0.000	0.000	0.000	0.000	0.000
	n	9	9	9	9	9	9
UCS of Mariam Church test pit	R	−0.979	1	0.965	0.965	0.958	0.979
	Sig.	0.000		0.000	0.000	0.000	0.000
	n	9	9	9	9	9	9
UCS of Ajip test pit	R	−0.988	0.965	1	0.989	0.960	0.983
	Sig.	0.000	0.000		0.000	0.000	0.000
	n	9	9	9	9	9	9
UCS of Aweytu test pit	R	−0.992	0.965	0.989	1	0.972	0.993
	Sig.	0.000	0.000	0.000		0.000	0.000
	n	9	9	9	9	9	9
UCS of Saris Sefer test pit	R	−0.987	0.958	0.960	0.972	1	0.974
	Sig.	0.000	0.000	0.000	0.000		0.000
	n	9	9	9	9	9	9
UCS of JIT campus test pit	R	−0.990	0.979	0.983	0.993	0.974	1
	Sig.	0.000	0.000	0.000	0.000	0.000
	n	9	9	9	9	9	9

Regression equations of UCS(measured)/UCS2.00 ratio for different specimen diameters versus H/D ratio.

Specimens’ diameter	Regression equations	R²	Correlation state	Equation number
38 mm	UCS_2.00=(UCS(measured))/(1.596-0.288(H/D))	0.928	Strong	3
50 mm	UCS_2.00=(UCS(measured))/(1.658-0.318(H/D))	0.938	Strong	4
100 mm	UCS_2.00=(UCS(measured))/(1.671-0.328(H/D))	0.941	Strong	5

Descriptive statistics of the peak UCS value for specimens of diameter 100 mm.

	Number of observations	Minimum (kPa)	Maximum (kPa)	Mean (kPa)	Std deviation	Skewness	Skewness std error	Kurtosis	Kurtosis std error
Mariam Church	9	155.66	313.46	222.71	50.06	0.434	0.717	−0.176	1.400
Ajip	9	209.21	372.44	281.48	58.61	0.338	0.717	−1.415	1.400
Aweytu	9	181.44	321.42	251.30	48.41	0.130	0.717	−1.134	1.400
Saris Sefer	9	126.06	281.43	210.98	56.46	−0.386	0.717	−1.181	1.400
JIT campus	9	225.62	465.21	340.70	77.48	0.142	0.717	−0.629	1.400

Regression model accuracy for the developed equations.

Specimens’ diameter of regression equations	MAE	MSE	RMSE	MAPE
38 mm	13.44	289.05	16.70	3.84%
50 mm	12.53	215.77	14.64	4.15%
100 mm	11.21	232.69	14.86	4.42%

Model summary of UCS/(UCS at 2 H/D ratios)-100 mm diameter and H/D ratio.

Model summary^b

Model	R	R²	Adjusted R²	Std error of the estimate
3	0.970^a	0.941	0.940	0.0540500

Specimens’ height for each diameter, with respect of their H/D ratio at stain rate of 1%/min.

H/D ratio	Specimen's diameter

	38 mm		50 mm		100 mm

	Height (mm)	Strain mm/min	Height (mm)	Strain mm/min	Height (mm)	Strain, mm/min
3.0	114	1.14	150	1.50	300	3
2.75	104.5	1.05	137.5	1.38	2750	2.75
2.5	95.0	0.95	125	1.25	250	2.50
2.25	85.5	0.86	112.5	1.13	225	2.25
2.0	76.0	0.76	100	1.00	200	2.00
1.75	66.5	0.67	87.5	0.88	175	1.75
1.5	57.0	0.57	75.0	0.75	150	1.50
1.25	47.5	0.48	62.5	0.63	125	1.25
1.00	38.0	0.38	50.0	0.50	100	1.00

Model summary of UCS/(UCS at 2 H/D ratio)-38 mm diameter and H/D ratio.

Model summary^b

Model	R	R²	Adjusted R²	Std error of the estimate
1	0.963^a	0.928	0.926	0.053191

Summary of index properties, classifications, and compaction parameters of the soils tested.

Parameters	Pit sites

	Ajib	Aweytu	Saris Sefer	JIT campus	Mariam Church
Liquid limit, %	79	49	72	86	75
Plastic limit, %	32	22	36	28	49
Plastic index, %	47	27	36	58	26
Percentage of course soil, %	0.0	10.7	0.0	0.0	0.2
Percentage of sandy soil, %	16.7	33.6	1.6	2.7	1.6
Percentage of fine soil, %	83.3	55.7	98.4	97.3	98.1
Soil classification
USCS	CH	CL	MH	CH	MH
Group name	High-plasticity clay soil	Low-plasticity clay soil	High-plasticity silty soil	High-plasticity clay soil	High High-Plasticity plasticity silty
AASHTO	A-7-5	A-7-6	A-7-5	A-7-6	A-7-5
Group name	Clayey soil	Clayey soil	Clayey soil	Clayey soil	Clayey soil
Standard Proctor compaction test
Optimum moisture content, %	34	23	26.5	39	37.5
Maximum dry density, g/cm³	1.27	1.51	1.38	1.3	1.31

Coefficients of UCS/(UCS at 2 H/D ratios)-38 mm diameter and H/D ratio.

Coefficients^a

Model		Unstandardized coefficients		Standardized coefficients	t	Sig.

		B	Std. Error	beta
1	(Constant)	1.596	0.026		61.838	0.000
1	H/D ratio	−0.288	0.012	−0.963	−23.469	0.000

Significance level (Sig.) and Pearson correlation coefficient (R) of UCS value for 38 mm specimen diameter.

		Height to diameter ratio	UCS of Mariam Church test pit	UCS of Ajip test pit	UCS of Aweytu test pit	UCS of Saris Sefer	UCS of JIT campus test pit
Height to diameter ratio (H/D)	R	1	−0.968^**	−0.979^**	−0.970^**	−0.984^**	−0.979^**
	Sig.		0.000	0.000	0.000	0.000	0.000
	n	9	9	9	9	9	9
UCS of Mariam Church test pit	R	−0.968^**	1	0.984^**	0.977^**	0.993^**	0.971^**
	Sig.	0.000		0.000	0.000	0.000	0.000
	n	9	9	9	9	9	9
UCS of Ajip test pit	R	−0.979^**	0.984^**	1	0.991^**	0.996^**	0.992^**
	Sig.	0.000	0.000		0.000	0.000	0.000
	n	9	9	9	9	9	9
UCS of Aweytu test pit	R	−0.970^**	0.977^**	0.991^**	1	0.988^**	0.995^**
	Sig.	0.000	0.000	0.000		0.000	0.000
	n	9	9	9	9	9	9
UCS of Saris Sefer test pit	R	−0.984^**	0.993^**	0.996^**	0.988^**	1	0.986^**
	Sig.	0.000	0.000	0.000	0.000		0.000
	n	9	9	9	9	9	9
UCS of JIT campus test pit	R	−0.979^**	0.971^**	0.992^**	0.995^**	0.986^**	1
	Sig.	0.000	0.000	0.000	0.000	0.000
	n	9	9	9	9	9	9

Significance level (Sig.) and Pearson correlation coefficient (R) of UCS value for 50 mm specimen diameter.

		Height to diameter ratio	UCS of Mariam Church test pit	UCS of Ajip test pit	UCS of Aweytu test pit	UCS of Saris Sefer	UCS of JIT campus test pit
Height to diameter ratio (H/D)	R	1	−0.994	−0.978	−0.973	−0.993	−0.986
	Sig.		0.000	0.000	0.000	0.000	0.000
	n	9	9	9	9	9	9
UCS of Mariam Church test pit	R	−0.994	1	0.983	0.981	0.997	0.987
	Sig.	0.000		0.000	0.000	0.000	0.000
	n	9	9	9	9	9	9
UCS of Ajip test pit	R	−0.978	0.983	1	0.989	0.988	0.991
	Sig.	0.000	0.000		0.000	0.000	0.000
	n	9	9	9	9	9	9
UCS of Aweytu test pit	R	−0.973	0.981	0.989	1	0.992	0.992
	Sig.	0.000	0.000	0.000		0.000	0.000
	n	9	9	9	9	9	9
UCS of Saris Sefer test pit	R	−0.993	0.997	0.988	0.992	1	0.995
	Sig.	0.000	0.000	0.000	0.000		0.000
	n	9	9	9	9	9	9
UCS of JIT campus test pit	R	−0.986	0.987	0.991	0.992	0.995	1
	Sig.	0.000	0.000	0.000	0.000	0.000
	n	9	9	9	9	9	9

Coefficients of UCS/(UCS at 2 H/D ratios)-50 mm diameter and H/D ratios.

Coefficients^a

Model		Unstandardized coefficients		Standardized coefficients	t	Sig.

		B	Std error	beta
2	(Constant)	1.658	0.026		63.201	0.000
2	H/D ratio	−0.318	0.012	−0.969	−25.509	0.000

Coefficients of UCS/(UCS at 2 H/D ratios)-100 mm diameter and H/D ratios.

Coefficients^a

Model		Unstandardized coefficients		Standardized coefficients	t	Sig.

		B	Std error	beta
3	(Constant)	1.671	0.026		63.699	0.000
3	H/D ratio	−0.328	0.012	−0.970	−26.238	0.000

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Effect of Specimens’ Height to Diameter Ratio on Unconfined Compressive Strength of Cohesive Soil

Article Category: Original Study

Published Online: Mar 09, 2023

Page range: 112 - 132

Received: Jun 05, 2022

Accepted: Nov 29, 2022

DOI: https://doi.org/10.2478/sgem-2023-0001

KeywordsHeight to diameter ratio, Unconfined compression strength, UCS scale effect

© 2023 Haile Tsegay Gebresamuel et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

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Model summary of UCS/(UCS at 2 H/D ratios)-50 mm diameter and H/D ratio.

Descriptive statistics of the peak UCS value for specimens of diameter 50 mm.

Descriptive statistics of the peak UCS value for specimens of diameter 38 mm.

Shapiro–Wilk normality test.

Significance level (Sig.) and Pearson correlation coefficient (R) of UCS value for 100 mm specimen diameter.

Regression equations of UCS(measured)/UCS2.00 ratio for different specimen diameters versus H/D ratio.

Descriptive statistics of the peak UCS value for specimens of diameter 100 mm.

Regression model accuracy for the developed equations.

Model summary of UCS/(UCS at 2 H/D ratios)-100 mm diameter and H/D ratio.

Specimens’ height for each diameter, with respect of their H/D ratio at stain rate of 1%/min.

Model summary of UCS/(UCS at 2 H/D ratio)-38 mm diameter and H/D ratio.

Summary of index properties, classifications, and compaction parameters of the soils tested.

Coefficients of UCS/(UCS at 2 H/D ratios)-38 mm diameter and H/D ratio.

Significance level (Sig.) and Pearson correlation coefficient (R) of UCS value for 38 mm specimen diameter.

Significance level (Sig.) and Pearson correlation coefficient (R) of UCS value for 50 mm specimen diameter.

Coefficients of UCS/(UCS at 2 H/D ratios)-50 mm diameter and H/D ratios.

Coefficients of UCS/(UCS at 2 H/D ratios)-100 mm diameter and H/D ratios.

Keywords
Height to diameter ratio, Unconfined compression strength, UCS scale effect