The DINGO database of axial pile load tests for the UK: settlement prediction in fine-grained soils

Figures & data

Figure 1. Distribution of the DINGO Database pile test in the main subcategories. (Some geology categories are overlapping, i.e. a single pile may be in multiple categories.)

Figure 2. GIS geology map showing the geographic distribution of the DINGO Database tests for fine-grained deposits.

Figure 3. Summary of analytical solution for nonlinear pile settlement considering shearing of concentric cylinders around the pile, pile compression, and non-linear stress-strain relation (strength mobilisation function from Vardanega and Bolton 2011a), hereafter referred to as “Model 1” (see Vardanega, Williamson, and Bolton 2012a; Vardanega et al. 2018 for further details on the development of the model). Symbols are defined in the notation list.

Figure 4. Summary of analytical solution for elastoplastic pile settlement considering elastic – perfectly plastic shaft resistance and bilinear tip resistance, hereafter referred to as “Model 2” (modified after Crispin, Leahy, and Mylonakis 2018, see also Voyagaki et al. 2019 for further details regarding Model 2). Symbols are defined in the notation list.

Table 1. Summary statistics of the DINGO pile test database included in this study.

Statistics of pile tests in fine-grained soils
Site locations	57	Pile diameter (m)	0.15–1.8
Number of test piles	186	Pile length (m)	3–39
		Pile slenderness ratio (L/Ds)	6–125
Pile types	Bored, straight shafted and under reamed	Max. applied load (MN)	27
Construction method	Maintained Load, Constant Rate of Penetration	Max. settlement (mm)	310
Geology^a	AMC, BAN, GLT, KC, LC, LMBE, MMG, OXC, PUCM, WBY + various superficial deposits	Max. normalised settlement wo/Ds (%)	15

^a See the Supplemental data for explanation of the Geology codes.

Table 2. Key Model Parameters.

Model Parameters^a
Factor of Safety (Ftotal)	Typical value of 2.5 is used
Concrete Pile Elastic Modulus (Ep, concrete)	30 GPa
Steel Pile Elastic Modulus (Ep, steel)	200 GPa
Adhesion factor (α)	0.5
Tip bearing capacity factor (Nc)	9
Ultimate skin friction per unit length (tu)	α cu π Ds
Soil shear modulus (Gs)	320 cu
Winkler modulus (k)	2 π Gs/ln [5 ρ (1 − νs) L/d] where ρ is the ratio of the mean and maximum Gs(z)
Base spring stiffness (Kb)	2 Gs(L) Db/(1 – νs)
Shear strain at 50% strength mobilisation (γM=2)	7 × 10^−3
Soil non-linearity exponent (b)	0.6
Soil Poisson’s ratio (νs)	0.5

^a Sources: Meyerhof (1976), Randolph and Wroth (1978), Poulos and Davis (1980), Fleming (1992), Patel (1992), Salgado (2008), Vardanega and Bolton (2011b); Vardanega et al. (2012b), LDSA (2017).

Table 3. Classification of the DINGO data set based on data quality category for the fine-grained soils subset (updated from Vardanega et al. 2021a).

Strength Parameter Source			Deformation Parameter Source
Category	Description	No. of Tests	Category	Description	No. of Tests
I	Soil descriptions and geology	7	A	High-quality lab test data from different sites in a similar deposit	80
II	In situ test data (e.g. SPT tests)	32	B	High-quality lab test data from different sites in the same deposit	106
III	Routine lab test data from on site (e.g. UU triaxial tests)	147	C	In situ test data (e.g. pressuremeter tests) or high-quality lab test data from on site	0
IV	High-quality lab test data from on site (e.g. CIU triaxial tests on undisturbed samples)	0	D	In situ test data and high-quality lab test data from on site	0

Figure 5. Site R37-05, pile TP1 (a) Soil profile; (b) undrained shear strength variation with depth; and (c) model parameters derived from the soil investigation data for a database site classified as high quality (IV) and; (d) corresponding predicted load-settlement curves plotted against test data.

Figure 6. Site R24-01, pile P1(a) Soil profile; (b) undrained shear strength variation with depth; and (c) model parameters derived from the soil investigation data for a database site classified as low quality (I) and; (d) corresponding predicted load-settlement curves plotted against test data.

Figure 7. Predicted versus measured pile head settlement plot for the full set of data analysed in this study (model parameters from Table 2).

Figure 8. Predicted versus measured pile head settlement plot for different values of factors of safety for the full set of data analysed in this study (model parameters from Table 2).

Figure 9. Predicted versus measured pile head settlement plot organised by soil parameter source (categories described in Table 3, model parameters from Table 2).

Figure 10. Predicted versus measured pile head settlement plot organised by geology category (parameters from Table 2).

Figure 11. Predicted versus measured pile head settlement plot organised by epoch of the tests (parameters from Table 2).

Figure 12. Predicted versus measured pile head settlement plot organised by construction method (parameters from Table 2).

Figure 13. Predicted versus measured pile head settlement plot organised by slenderness of the test pile (parameters from Table 2).

Figure 14. Predicted versus measured pile head settlement comparing Model 1 and Model 2 (parameters from Table 2).

Table 4. Statistics of the model bias factors B (Equation 4) and model error presented in Figures 7–13.

Case	Ftotal	Figure	N	Statistics of the Bias B = measured/predicted						Statistics of the Absolute Error |predicted − measured|/measured %
				Model 1			Model 2			Model 1			Model 2
				Mean	σ	COV	Mean	σ	COV	Mean	σ	COV	Mean	σ	COV
Full dataset	5	8(a)	186	1.25	1.9	1.52	1.18	1.71	1.44	100	194	1.92	105	193	1.84
	3	8(b)	174	1.57	3.45	2.19	1.73	3.48	2.01	82	117	1.42	69	80	1.15
	2.5	7	161	1.6	3.9	2.44	1.83	4.16	2.27	77	110	1.44	59	69	1.18
	2	8(c)	147	2	6.71	3.3	2.7	7.88	3.1	78	111	1.41	57	72	1.27
	1.5	8(d)	96	1.5	2.88	1.93	2.18	5.54	2.53	92	135	1.47	60	102	1.71
Category IA	2.5	9(a)	7	0.66	0.24	0.37	0.75	0.26	0.34	80	99	1.23	57	85	1.50
Category IIA		9(b)	24	1.04	0.48	0.46	1.25	0.59	0.47	53	75	1.41	47	62	1.33
Category IIIA		9(c)	41	1.80	3.24	1.80	1.91	3.21	1.69	115	195	1.69	78	110	1.42
Category IIIB		9(d)	92	1.73	4.71	2.73	2.03	5.09	2.5	67	55	0.83	53	41	0.77
London Clay	2.5	10(a)	92	1.63	4.67	2.86	1.86	4.95	2.66	66	55	0.83	52	41	0.78
Mercia Mudstone		10(b)	34	0.87	0.45	0.52	1.07	0.58	0.54	88	200	2.26	63	109	1.73
Gault Clay		10(c)	9	0.65	0.20	0.30	0.82	0.23	0.28	85	126	1.49	45	92	2.03
Other		10(d)	26	2.75	3.89	1.41	3.08	4.29	1.39	96	89	0.93	82	73	0.89
1950–1989	2.5	11(a)	110	1.57	4.32	2.76	1.85	4.67	2.52	72	70	0.98	53	51	0.96
1990-present		11(b)	51	1.67	2.81	1.68	1.78	2.79	1.56	88	167	1.89	70	97	1.38
Bored	2.5	12(a)	133	1.42	3.94	2.78	1.66	4.27	2.57	73	71	0.98	56	55	0.98
CFA		12(b)	12	4.65	4.76	1.03	4.93	4.55	0.92	65	42	0.64	70	34	0.49
Driven Concrete		12(c)	4	1.14	0.87	0.76	1.16	0.77	0.67	316	577	1.83	181	305	1.68
Driven Steel		12(d)	3	0.86	0.13	0.15	0.79	0.12	0.15	18	17	0.91	29	19	0.64
L/Ds < 25	2.5	13(a)	84	1.57	2.44	1.56	1.92	2.82	1.47	74	70	0.94	58	52	0.91
L/Ds ≥ 25		13(b)	77	1.63	5.05	3.09	1.73	5.27	3.04	80	143	1.79	60	84	1.40

Table A1. Summary of 57 pile test sites from the DINGO Database analysed in this study (Geology codes are listed in DINGO Database (Vardanega et al. 2021b)).

DINGO Project ID	Location	Number of				DINGO Categories
		Boreholes	SPTs	Triaxial Tests	Test Piles	Construction Type	Geology	Quality	Year
D04_01	Childsbridge Lane	2	0	0	2	BOR	GLT	IIIA	1978
D04_02	Cockney Wood Accomodation Bridge	1	0	0	1	BOR	GLT	IIIA	1978
D04_03	Darent River	2	0	0	2	BOR	GLT	IIIA	1978
D04_06	Oxenhillshaw	2	0	0	2	BOR	GLT	IIIA	1978
D04_07	Park lane Accomodation Bridge	1	0	0	1	BOR	HEAD,GLT	IIIA	1978
D04_09	St. Clere South Abutment	1	0	0	1	BOR	GLT	IIIA	1978
D07_01	Huntingdon Road, Cambridge, CB24 4AE	1	0	0	1	BOR	AMC	IIIA	2018
D07_02	Mere Way, Huntingdon, PE28	1	0	0	1	BOR	HEAD,OXC	IIIA	2018
D07_04	Buckden Road, Brampton, Huntingdon, PE28	1	0	0	1	BOR	TILL,WHCK,OXC	IIIA	2018
D07_05	B1043	1	0	0	1	BOR	RTD,TILL	IIIA	2018
D07_06	A1, Brampton, Huntingdon, PE28 4NQ	1	0	0	1	BOR	ALV,RTD,OXC	IIIA	2018
D07_07	A1198, Godmanchester, Huntingdon, PE29 2LJ	1	0	0	1	BOR	TILL,OXC	IIIA	2018
D07_08	B1050, Longstanton, Cambridge, CB23 8DS	1	0	0	1	BOR	KC,AMC	IIIA	2018
D09	Stanford Hall, Loughborough	5	0	0	5	CFA	SUPD,BAN,WBY	IIIA	2012
D10	Etihad Campus, Manchester	13	280	0	11	BOR	TILL,PUCM	IIA	2000
R01_01	Wimbledon, London	1	0	14	3	BOR, CFA	ALV,LC	IIIB	2008
R01_02	Chessington	1	0	43	1	BOR	LC	IIIB	2008
R05	Waltham, Grimsby Depot, Grimsby	2	15	51	1	BOR	BOC	IIIA	2001
R09	Hendon, North London	2	0	10	3	DRI_S	LC	IIIB	1979
R11	Manchester Airport	18	110	0	16	BOR, CFA, DRI_S	TILL,MMG	IIA	1996
R12	Birmingham (national exhibition centre)	5	53	0	2	BOR	MMG	IIA	1984
R14	Tanners End Lane, Edmonton, London	13	0	24	7	BOR	RTD,LC,LMBE	IIIB	1978
R15	Leicester	2	7	7	2	BOR	MMG	IIIA	1971
R17	Kensal Green Gas Works	1	0	84	3	BOR	LC	IIIB	1954
R18	Borehamwood, Hertfordshire	1	0	0	8	BOR	LC	IIIB	1955
R21	Burnaston, to the southwest of Derby	26	51	30	14	BOR, DRI_C	TILL,MMG	IIIA	1995
R22	Westbourne Park Station, London	2	0	29	9	CFA	LC	IIIB	1980
R24_02	Grangetown Link (Clarens Bridge), Cardiff	1	0	0	2	BOR	MMG	IA	1989
R24_03	Eastmoors Link, Cardiff	3	128	0	6	BOR	MMG	IIA	1989
R24_04	Grangetown Link & Cogan Spur, Cardiff	1	0	0	4	BOR	MMG	IA	1989
R27	Kilroot, County Antrim, Northern Ireland	1	140	95	3	BOR	GLT,MMG,UEXG	IIIA	1976
R29	Bothkennar, Forth Estuary, Scotland	1	0	90	12	CFA	ITDU	IIA	1992
R31	Aldgate Place, Whitechapel, east London	5	63	82	1	BOR	RTD,LC,LMBE	IIIB	2013
R32	Wembley Stadium in north London	4	72	0	2	BOR	LC	IIA	2014
R33_01	Southall	1	0	29	7	BOR	LC	IIIB	1953
R33_02	Barnet	1	0	29	6	BOR,DRI_C	LC	IIIB	1953
R34	Cardiff (Taff Viaduct)	7	64	0	6	BOR	RTD,MMG,SUPD	IIIA	1992
R35	British Library, London	1	98	0	2	BOR	LC,LMBE,TAB,WHCK	IIIA	1982
R37_01	Lambeth, London	1	0	27	2	BOR	LC	IIIB	1988
R37_02	Lambeth, London	1	0	8	1	BOR	LC	IIIB	1970
R37_03	Oxhey, Watford, London	1	0	22	1	BOR	LC	IIIB	1970
R37_04	Wilson St, London	1	0	18	1	BOR	RTD,LC	IIIB	1970
R37_05	Broadmead Rd, Brickfield, London	2	0	50	2	BOR	RTD,LC	IIIB	1966
R37_06	Kidbrooke, Greenwich, London	1	0	96	12	BOR	LC	IIIB	1968
R37_07	Brentford, London	1	0	63	2	BOR	RTD,LC	IIIB	1968
R37_08	Cambridge Rd, Kingston, London	2	0	67	2	BOR	LC	IIIB	1968
R37_09	Cambridge Rd, Girdlestone Rd, Highgate, London	1	0	76	6	BOR	LC	IIIB	1972
R37_10	Woodgreen Shopping Centre, Wood Green, London	5	0	20	5	BOR	LC,LMBE	IIIB	1972
R37_11	Loughborough Park, Brixton, London	2	0	41	2	BOR	RTD,LC	IIIB	1971
R37_12	Pond St, Hampstead, London	2	0	119	2	BOR	LC	IIIB	1968
R37_13	Prince of Wales Rd, Hampstead, London	1	0	43	2	BOR	LC	IIIB	1969
R37_14	Keatley Green, London	7	0	74	7	BOR	ALV,LC	IIIB	1969
R37_15	Canon Street Station, London	3	0	51	3	BOR	LC	IIIB	1969
R38	Chattenden, Kent	1	0	32	28	CFA,BOR,MISC,DRI_C	LC	IIIB	2013
R44	London’s Heathrow Airport	1	0	0	1	BOR	RTD,LC	IIIB	2001
R45	Alperton Lane, Wembley, Middlesex	1	0	95	12	BOR	LC	IIIB	1966
R46	Angel Square, Islington, London	2	78	66	2	BOR	LC,LMBE,TAB	IIIB	1993

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Data availability

The underlying data used for the analysis presented in this paper can be sourced from the DINGO database which can be freely downloaded from the data.bris repository via the following weblink: https://doi.org/10.5523/bris.89r3npvewel2ea8ttb67ku4d (Vardanega et al. 2021b).