Research on correlation between compression index (Cc) and other properties of soil for geotechnical design in coastal regions of Vietnam and cambodia

doi:10.15406/mojce.2017.02.00034

MOJ

eISSN: 2572-8520

Civil Engineering

Review Article Volume 2 Issue 3

Research on correlation between compression index (Cc) and other properties of soil for geotechnical design in coastal regions of Vietnam and cambodia

Phi Hong Thinh,

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Hoang Anh Tuan, Doan Cong Bien, Nguyen Hai Ha

Department of Civil Engineering, University of Transport and Communications, Vietnam

Correspondence: Phi Hong Thinh, Department of Civil Engineering, University of Transport and Communications, Vietnam

Received: February 17, 2017 | Published: March 16, 2017

Citation: Thinh PH, Tuan HA, Bien DC, et al. Research on correlation between compression index (Cc) and other properties of soil for geotechnical design in coastal regions of Vietnam and cambodia. MOJ Civil Eng. 2017;2(3):97-101. DOI: 10.15406/mojce.2017.02.00034

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Abstract

Compression index (C_c) takes an important role in settlement prediction for engineering foundation. Value of C_c depends heavily on methods of taking sample, sample transportation, quality of laboratory testing equipment, laboratory staff experience. These works are not well controlled in developing countries such as Vietnam and Cambodia. Our research is to find out the most suitable correlation between Cc and other properties of weak soil layer in coastal regions of Vietnam and Cambodia. From that, authors propose a new formula showing the correlation between C_cand liquid limit (LL) of the soil layer for geotechnical design in Vietnam and Cambodia.

Keywords: compression index (cc), correlation, settlement

Introduction

International and Vietnamese scientists have proposed many correlations between physical and mechanical properties of soil for geotechnical design. But, only some of them are suitable for construction areas in Vietnam and Cambodia. This research will find out and propose some suitable correlations between some physical and mechanical properties of very soft to soft dark grey lean Clay in these areas. This weak soil layer has wide distribution and great thickness and greatly affects stability and settlement of construction works, but methods of taking sample, sample transportation, quality of laboratory testing equipment, laboratory staff experience and in-situ tests performed in the layer do not often meet the technical requirements for geotechnical design in Vietnam and Cambodia. Data used in this paper are received from geotechnical investigation results in Quang Ninh, Nghe An, Soc Trang, Quang Ngai provinces, Ho Chi Minh city of Vietnam and Sihanoukville province of Cambodia. Research areas are shown in Figure 1 below.

Overview of the study subject

The meaning of compression index (Cc) in geotechnical design

Compression index (Cc) is mentioned in a lot of construction standards in Vietnam and other countries in the world. It takes an important role in settlement prediction for engineering foundation.

Settlement prediction of each soil layer is calculated by the following formula:

$Δ S_{c} = \frac{C_{c}}{1 + e_{0}} H_{i} \log (\frac{{σ^{'}}_{o} + Δ {σ^{'}}_{}}{{σ^{'}}_{o}})$

Where:

ΔSc : Consolidation settlement of the soil layer;

Cc: Compression index;

Hi: The thickness of the soil layer.

eo: Initial void ratio.

σ’o: Initial stress at the middle of the soil layer.

Δσ’: Effective stress increase at the middle of the soil layer.

Therefore, the evaluation and determination of correlation between Cc and other properties of soil have extremely important meaning in geotechnical design.

Research areas in Vietnam and Cambodia

Vietnam's coastline stretches the entire length of the country, about 3260 kilometers and just about 443 kilometers for Cambodia. Vietnam and Cambodia have a tropical monsoon climate, large rainfall amount. The geological structure of the research areas contains a thick, soft to very soft marine dark grey lean clay layer with the thickness of 5 to 50m (Figure 2) which creates dangerous engineering-geological processes, including land subsidence and deformation of buildings and other structures.

Average value of some physical and mechanical properties of the layer is as follows:

Natural moisture content (W): 55.8 - 53.3%;

Natural unit weight (ρ): 1.62 - 1.58 g/cm3;

Natural void ratio (eo): 1.470 - 1.400;

Liquid limit (LL): 45 - 60%;

Plasticity index (PI): 16.9 - 15.9%;

Cohesion (c): 7.0 - 8.9kPa;

Internal friction angle (φ): 5033’ - 5049’;

Compression index (Cc): 0.40 - 0.58.

Figure 1 Location map of research areas

Figure 2 Distribution of marine clay in South East Asia (Cox, 1968).

Some correlations between Cc and other properties of soil

There are a lot of formulas showing the correlation between Cc and other properties of soils proposed by famous scientists in the world. Below some formulas showing correlation between Cc and other properties such as void ratio (e0), moisture content (W), liquid limit (LL), plasticity index (PI) are listed in Table 1.

Formula	Proposed by
Cc = 0.007(LL - 7.0%)	Skempton (1944)
Cc = 1.15(e0 - 0.35)	Nishida (1956)
Cc = 0.29(e0 - 0.27)	Hough (1957)
Cc = 0.256 + 0.43(e0 - 0.84)	Cozzolino (1961)
Cc = 0.0046(LL - 9.0%)	Cozzolino (1961)
Cc = 0.009(LL - 10.0%)	Terzaghi & Peck (1967)
Cc = 0.75(W - 0.5)	Sowers (1970)
Cc = 0.006(LL - 9.0%)	Azzouz et al. (1976)
Cc = 0.037(e0 - 0.003LL - 0.34)	Azzouz et al. (1976)
Cc= 0.01(W - 7.549%)	Herrero (1983)
Cc = 0.54(e0 - 0.23)	Moh a kol. (1989)
Cc = 0.007(LL - 7.0%)	Moh a kol. (1989)
Cc = 0.009(LL - 8.0%)	Tsuchida (1991)
Cc = 0.014(PI + 3.6%)	Sridharan & Nagaraj (2000)

Table 1 Some correlation between Cc and other properties of soil

The suitable correlation between Cc and other properties of soil in coastal regions of vietnam and cambodia

Based on data received from the geotechnical investigation results in Quang Ninh, Nghe An, Soc Trang, Quang Ngai provinces, Ho Chi Minh city of Vietnam and Sihanoukville province of Cambodia carried out from 2010 to 2016, correlation between Cc and other properties of weak soil layer in coastal areas of Viet Nam and Cambodia is analysed Table 2-8.

Some formulas in Table 1 and a formula proposed by authors [Cc= 0.009(LL-2.0%)] are used for analysis. The values of Cc determined by these formulas are compared with Cc received from laboratory testing results. The Cc received from laboratory testing results is considered as standard values for analysis. Analysis results are shown in tables and figures below (Figure 3-9). Correlation between Cc & other properties of soil at Sihanoukville province. The research results show that the value of Cc received from Terzaghi & Peck’s formula is close to Cc received from laboratory testing results; and Cc received from formula proposed by the authors is not deferent from Cc received from laboratory testing results.^1-8

No.	Soil Name	PI (%)	e0	LL (%)	ρ g/cm3)	Sridha- ran and Nagaraj	Hough	Tsuchi-da	Skemp-ton	Terza-ghi and Peck	Proposed by Authors	Lab
No.	Soil Name	PI (%)	e0	LL (%)	ρ g/cm3)	Sridha- ran and Nagaraj	Hough	Tsuchi-da	Skemp-ton	Terza-ghi and Peck	Proposed by Authors	Lab
1	Lean clay with sand	8.20	0.82	26.31	1.92	0.17	0.16	0.16	0.14	0.15	0.22	0.25
2	Fat clay with sand	32.51	1.51	50.69	1.63	0.51	0.36	0.38	0.31	0.37	0.44	0.40
3	Fat clay	51.88	3.30	88.67	1.37	0.78	0.88	0.73	0.57	0.71	0.78	0.70
4	Lean clay with sand	25.02	1.12	43.98	1.79	0.40	0.25	0.32	0.26	0.31	0.38	0.38
5	Fat clay with sand	33.09	1.26	53.68	1.76	0.51	0.29	0.41	0.33	0.39	0.47	0.45
6	Fat clay	37.31	2.06	63.77	1.51	0.57	0.52	0.50	0.40	0.48	0.56	0.58
7	Fat clay	36.96	2.01	59.18	1.52	0.57	0.50	0.46	0.37	0.44	0.51	0.45
AVERAGE		32.14	1.72	55.18	1.64	0.50	0.59	0.59	0.47	0.57	0.48	0.46

Table 2 Determination of Cc at Cai Lan Port - Quang Ninh province

No.	Soil Name	PI (%)	e0	LL (%)	ρ (g/cm3)	Sridha- ran and Nagaraj	Hough	Tsuchi-da	Skemp-ton	Terza-ghi and Peck	Propo-sed by Autho-rs	Lab.
No.	Soil Name	PI (%)	e0	LL (%)	ρ (g/cm3)	Sridha- ran and Nagaraj	Hough	Tsuchi-da	Skemp-ton	Terza-ghi and Peck	Propo-sed by Autho-rs	Lab.
1	Lean clay	22.82	1.43	45.82	1.68	0.37	0.34	0.34	0.27	0.32	0.39	0.38
2	Lean clay	21.53	1.15	41.58	1.79	0.35	0.26	0.30	0.24	0.28	0.36	0.37
3	Organic clay	24.32	1.48	48.21	1.68	0.39	0.35	0.36	0.29	0.34	0.42	0.45
4	Silty clay	25.81	1.55	51.07	1.64	0.41	0.37	0.39	0.31	0.37	0.44	0.44
5	Lean clay	20.23	1.21	38.84	1.77	0.33	0.27	0.28	0.22	0.26	0.33	0.37
6	Lean clay	10.71	0.83	25.53	1.91	0.20	0.16	0.16	0.13	0.14	0.21	0.20
7	Organic silt	22.40	1.52	42.89	1.66	0.36	0.36	0.31	0.25	0.30	0.37	0.38
8	Organic silt	26.25	1.66	50.48	1.63	0.42	0.40	0.38	0.30	0.36	0.44	0.50
AVERAGE		7.57	0.47	14.97	0.60	0.36	0.32	0.32	0.26	0.30	0.38	0.38

Table 3 Determination of Cc at Ha Long city - Quang Ninh province

N o.	Soil Name	PI (%)	e0	LL (%)	ρ (g/cm3)	Sridha- ran and Nagaraj	Hough	Tsuchi-da	Skemp-ton	Terza-ghi and Peck	Proposed by Autho-rs	Lab
N o.	Soil Name	PI (%)	e0	LL (%)	ρ (g/cm3)	Sridha- ran and Nagaraj	Hough	Tsuchi-da	Skemp-ton	Terza-ghi and Peck	Proposed by Autho-rs	Lab
1	Lean clay	16.60	1.48	36.20	1.68	0.28	0.35	0.25	0.20	0.24	0.31	0.28
2	Lean clay	16.40	1.53	35.70	1.68	0.28	0.37	0.25	0.20	0.23	0.30	0.30
3	Lean clay	22.40	1.55	44.00	1.67	0.36	0.37	0.32	0.26	0.31	0.38	0.40
4	Fat clay	30.80	2.07	60.30	1.54	0.48	0.52	0.47	0.37	0.45	0.52	0.50
5	Lean clay	24.00	1.50	48.20	1.68	0.39	0.36	0.36	0.29	0.34	0.42	0.40
6	Lean clay	23.70	1.64	47.50	1.65	0.38	0.40	0.36	0.28	0.34	0.41	0.41
7	Fat clay	25.50	1.84	52.40	1.57	0.41	0.46	0.40	0.32	0.38	0.45	0.43
8	Fat clay	25.90	1.80	50.00	1.58	0.41	0.44	0.36	0.29	0.35	0.43	0.42
AVERAGE		18.53	1.34	37.43	1.31	0.30	0.33	0.28	0.22	0.26	0.43	0.45

Table 4 Determination of Cc at Cua Lo Town - Nghe an province

N o.	Soil name	PI (%)	e0	LL (%)	ρ (g/cm3)	Sridha- ran and Nagaraj	Hough	Tsuchi-da	Skemp-ton	Terza-ghi and Peck	Propo-sed by Autho-rs	Lab
N o.	Soil name	PI (%)	e0	LL (%)	ρ (g/cm3)	Sridha- ran and Nagaraj	Hough	Tsuchi-da	Skemp-ton	Terza-ghi and Peck	Propo-sed by Autho-rs	Lab
1	Fat Clay	31.50	1.11	57.60	1.80	0.49	0.24	0.45	0.35	0.43	0.50	0.48
2	Fat Clay	33.70	1.38	67.30	1.70	0.52	0.32	0.53	0.42	0.52	0.59	0.54
3	Fat Clay	38.20	1.40	65.70	1.68	0.59	0.33	0.52	0.41	0.50	0.57	0.55
4	Fat Clay	50.50	1.70	81.00	1.62	0.76	0.41	0.66	0.52	0.64	0.71	0.70
5	Fat Clay	41.90	1.46	79.00	1.65	0.64	0.35	0.64	0.50	0.62	0.69	0.66
6	Fat Clay	44.80	1.60	78.90	1.63	0.68	0.38	0.64	0.50	0.62	0.69	0.65
7	Fat Clay	24.20	1.28	51.30	1.71	0.39	0.29	0.39	0.31	0.37	0.44	0.40
AVERAGE		22.07	0.83	40.07	0.98	0.54	0.33	0.53	0.42	0.51	0.58	0.55

Table 5 Determination of Cc at Quang Ngai province

No	Soil Name	PI (%)	e0	LL (%)	ρ (g/cm3)	Sridha- ran and Nagaraj	Hough	Tsuchi-da	Skemp-ton	Terza-ghi and Peck	Propo-sed by Autho-rs	Lab
No	Soil Name	PI (%)	e0	LL (%)	ρ (g/cm3)	Sridha- ran and Nagaraj	Hough	Tsuchi-da	Skemp-ton	Terza-ghi and Peck	Propo-sed by Autho-rs	Lab
1	Fat clay	48.70	2.01	83.40	1.56	0.73	0.50	0.68	0.53	0.66	0.73	0.7
2	Fat clay	26.30	1.45	53.10	1.69	0.42	0.34	0.41	0.32	0.39	0.46	0.46
3	Fat clay with sand	24.80	1.46	51.60	1.68	0.40	0.35	0.39	0.31	0.37	0.45	0.45
4	Fat clay with sand	23.10	1.38	44.50	1.66	0.37	0.32	0.33	0.26	0.31	0.38	0.40
5	Fat clay	40.10	1.87	73.40	1.58	0.61	0.46	0.59	0.46	0.57	0.64	0.63
6	Fat clay	42.90	1.75	72.20	1.60	0.65	0.43	0.58	0.46	0.56	0.63	0.63
AVERAGE		34.32	1.65	63.03	1.63	0.53	0.40	0.50	0.39	0.48	0.55	0.6

Table 6 Determination of Cc at Ho Chi Minh city

N o.	Soil Name	PI (%)	e0	LL (%)	ρ (g/cm3)	Sridha- ran and Nagaraj	Hough	Tsuchi-da	Skemp-ton	Terza-ghi and Peck	Propo-sed by Auth-ors	Lab
N o.	Soil Name	PI (%)	e0	LL (%)	ρ (g/cm3)	Sridha- ran and Nagaraj	Hough	Tsuchi-da	Skemp-ton	Terza-ghi and Peck	Propo-sed by Auth-ors	Lab
1	Lean clay	26.00	1.48	49.10	1.65	0.41	0.35	0.37	0.29	0.35	0.42	0.43
2	Fat clay	31.30	1.56	56.60	1.65	0.49	0.37	0.44	0.35	0.42	0.49	0.49
3	Fat clay	33.40	1.60	59.40	1.64	0.52	0.39	0.46	0.37	0.44	0.52	0.54
4	Fat clay	25.40	1.58	52.00	1.65	0.41	0.38	0.40	0.32	0.38	0.45	0.47
5	Fat clay	33.70	1.52	56.30	1.64	0.52	0.36	0.43	0.35	0.42	0.49	0.52
6	Fat clay	35.3	1.57	63.1	1.63	0.54	0.38	0.50	0.39	0.48	0.55	0.54
7	Fat clay	26	1.54	50.9	1.62	0.41	0.37	0.39	0.31	0.37	0.44	0.53
9	Fat clay	35.7	1.52	63.4	1.67	0.55	0.36	0.50	0.39	0.48	0.55	0.53
AVERAGE		22.44	1.12	40.98	1.20	0.46	0.37	0.42	0.33	0.40	0.47	0.47

Table 7 Determination of Cc at Soc Trang province

N o.	Soil name	PI (%)	e0	LL (%)	ρ (g/cm3)	Sridha- ran and Nagaraj	Hough	Tsuchi-da	Skemp-ton	Terzaghi and Peck	Proposed by Auth-ors	Lab
N o.	Soil name	PI (%)	e0	LL (%)	ρ (g/cm3)	Sridha- ran and Nagaraj	Hough	Tsuchi-da	Skemp-ton	Terzaghi and Peck	Proposed by Auth-ors	Lab
1	Fat clay with sand	24.30	2.03	51.10	1.55	0.39	0.51	0.39	0.31	0.37	0.44	0.42
2	Sandy fat clay	22.80	2.55	51.30	1.44	0.37	0.66	0.39	0.31	0.37	0.44	0.45
3	Sandy lean clay	14.80	1.58	35.90	1.57	0.26	0.38	0.25	0.20	0.23	0.31	0.32
4	Sandy lean clay	22.30	2.08	50.20	1.51	0.36	0.53	0.38	0.30	0.36	0.43	0.40
5	Sandy lean clay	20.30	1.62	45.00	1.63	0.33	0.39	0.33	0.27	0.32	0.39	0.39
6	Sandy fat clay	26.70	1.75	53.60	1.60	0.42	0.43	0.41	0.33	0.39	0.46	0.45
AVERAGE		21.87	1.94	47.85	1.55	0.36	0.48	0.36	0.29	0.34	0.41	0.41

Table 8 Determination of Cc at Sihanoukville province, Cambodia

Figure 3 Correlation between Cc & other properties of soil at Cai Lan Port

Figure 4 Correlation between Cc & other properties of soil at Ha Long city

Figure 5 Correlation between Cc & other properties of soil at Nghe an province.

Figure 6 Correlation between Cc & other properties of soil at Quang Ngai province.

Figure 7 Correlation between Cc & other properties of soil at Quang Ngai province.

Figure 8 Correlation between Cc & other properties of soil at Soc Trang province.

Figure 9 Correlation between Cc & other properties of soil at Sihanoukville province.

Conclusion and recommendation

In coastal regions of Vietnam and Cambodia, there is a thick, soft to very soft marine dark grey lean clay layer which creates dangerous engineering-geological processes, including land subsidence and deformation of buildings and other structures.

Compression index (Cc) takes an important role in settlement prediction for engineering foundation. Value of Cc depends heavily on methods of taking sample, sample transportation, quality of laboratory testing equipment, laboratory staff experience. These works are not well controlled in developing countries such as Vietnam and Cambodia. The research focuses on the correlation between Cc and other properties of the layer. Research results show that the correlation between Cc and Liquid limit is the tightest. The formula proposed by Terzaghi & Peck is suitable correlation between Cc and LL. The authors revised Terzaghi & Peck’s formula and proposed a new formula [Cc= 0.009(LL-2.0%)]. The research results show that this formula is the most suitable one for the correlation between Cc and LL of the layer in research areas.

We recommend to use the correlation Cc= 0.009(LL-2.0%) for the clay layer in coastal regions of Vietnam and Cambodia.

Acknowledgements

The authors wish to thank Mr. Dao Xuan Quang, general director of EGS Vietnam Ltd, Transport Engineering Design Incorporation (TEDI) and Vietnamese colleagues for providing us input data. We also want to thank Mr. Elan Phillips for his valuable comments on the manuscript.