Analysis of the Historical Settlements of the Giralda

Figures & data

Figure 1. Localisation of the Giralda tower of the Cathedral of Seville.

Figure 2. Schematic diagram of the methodology.

Figure 3. Major mosque superimposed on the Gothic Cathedral floor (based on the hypothesis of A. Jimenez and A. Almagro). Photography of the Giralda tower (1) and the induced settlement on the Lagarto” gate (2).

Figure 4. Giralda tower foundation, east façade elevation and plan (based on the archaeological studies carried out by Tabales (Tabales Rodríguez 1998)). North elevation of the Islamic minaret of the Major Mosque (based on the hypothesis of A. Almagro (Almagro-Gorbea and Zúñiga-Urbano 2007)(Almagro-Gorbea 2012)). Dimensions in metres.

Figure 5. Giralda tower foundation, south and north façade elevation (based on the archaeological studies carried out by Tabales (Tabales-Rodríguez 1998)).

Table 1. Pressure applied to the base of the foundation for the construction phases.

Construction phase	Year	Pressure (kPa)	Cumulative pressure (kPa)
1 Construction of the foundation and the base of stone blocks	1184	75.30	75.30
2 Construction of Islamic minaret	1188–1198	529.5	604.80
3 Construction of the bell tower	1558–1568	47.80	652.60

Table 2. Stratigraphy of the soil and layer thickness.

Level	Layer thickness	Stratigraphy
I	3.00 m (0.00 m to 2.50-3.00 m)	Composed of several layers of infill. Under the pavement, there is a sandy subbase with gravel of a brown tonality. Next, there are several silty marl layers with traces of sand, gravel, ceramic and organic matter.
II	5.00 m (2.00-3.00 m to 7.00-9.00 m)	Fine and soft alluvial infill. This is just under the tower foundation and it is composed of an anthropic fill with ceramic traces, clayey sand, silts, ceramic brick traces and organic matter.
III	4.00 m (7.00-9.00 m to 11.00-12.00 m)	Composed of grey clays with sands, gravel and ceramic traces.
IV	6.00 m (11.00-12.00 m to 17.90-18.40 m)	Alluvial substrate composed of sandy gravel with traces of silt and clay.
V	(17.90-18.50m / --)	The Tertiary substrate. The blue Guadalquivir marls.

Figure 6. Geotechnical profiles (GP) under the tower. Dimensions in metres.

Table 3. Geotechnical properties of the strata.

			LEVEL I	LEVEL II	LEVEL III	LEVEL IV	LEVEL V
Drainage type			Drained	Undrained	Undrained	Drained	Undrained
Unit weight	γ	(kN/m3)	20	19.2	19.1	19	19.2
Saturated unit weight	γsat	(kK/m3)	20.9	20.8	20.4	20	19.6
Permeability	kx	(m/s)	10E-04	10E-07	10E-10	10E-03	10E-12
Water content	w	(%)	20	28.8	26.8	7.5	24.9
Compression Index	Cc	(-)	0.119	0.153	0.172	-	0.12
Recompression index	Cs	(-)	0.0119	0.0153	0.0172	-	0.012
Void ratio	e0	(-)	0.5	0.5	0.5	-	0.5
Effective cohesion	c´	(kPa)	10	29.4	22	10	100.5
Angle of internal friction	Փ	(°)	28°	30°	26°	32°	20°
Dilatance angle	ψ	(°)	0	0	0	2°	0
Elastic oedometer modulus	Eoed	(kPa)	5 000	5 428	6 165	50,000	90,000
Morh-Coulomb model
Shear Modulus	G	(kN/m2)	1428.6	1550.9	1761.4	14,285.7	25,714.3
Effective Young´s modulus	E´	(kPa)	3714.3	4032.2	4579.7	37,142.9	66,857.1
Effective Poisson´s ratio	ʋ	(-)	0.30	0.35	0.35	0.30	0.25
Soft Soil model
Modified compression index	λ*	(-)	0.034	0.044	0.050	-	0.035
Modified swelling index	k*	(-)	0.007	0.009	0.010	-	0.007

Table 4. Properties of the foundation base.

	γ (kN/m3)	γsat (kK/m3	γd (kN/m3)	w (%)	qu (kPa)	c´ (kPa)	Փ (°)	E (kN/m2)	G (kN/m2)	E´(kN/m2)	υ
Mortar Base	19	20	15.6	28	5 070	15	40	500,000	228,900	526,470	0,15

Table 5. Settlement for each point and construction phase. Results in centimetres.

		P1	P2	P3	P4	P5	P6
MC	SE	−4.1	−13.8	−49.1	−78.3	−80.2	−82.6
	NE	−4.0	−13.4	−47.0	−75.6	−77.5	−79.8
	NW	−3.8	−12.2	−46.8	−73.7	−75.5	−77.6
	SW	−3.8	−12.6	−48.9	−76.5	−78.2	−80.5
	C	−4.0	−13.1	−48.6	−76.6	−78.5	−80.8
SS	SE	−2.0	−28.1	−61.7	−102.7	−103.2	−105.5
	NE	−2.0	−28.1	−57.2	−97.1	−97.6	−99.8
	NW	−2.1	−26.8	−57.0	−94.0	−94.6	−96.5
	SW	−2.1	−26.8	−61.5	−99.7	−102.0	−102.2
	C	−2.0	−27.5	−60.0	−99.1	−99.7	−101.8

Figure 7. Discretisation and measurement points of the 3D FEM.

Figure 8. Total mesh displacement of the MC model. Section GP2 (a) and GP4 (b).

Figure 9. Total displacement of the MC model. Section from the south-east to the north-west corner.

Figure 10. Settlements as a function of time (MC model) (a) All phases using a logarithmic scale (b) Enlargement plot of the construction and consolidation of the Alminar (P4 and P5). (SE, SW, NE and NW points).

Figure 11. Total displacement of Soft-Soil model. Section north-south (a) and section west-east (b).

Figure 12. Total displacement for the SS model. Section from the south-east to the north-west corner.

Figure 13. Settlements as a function of time (SS model) (a) All phases using a logarithmic scale (b) Enlargement of the construction (P3) and consolidation of the Alminar (P4) (SE, SW, NE and NW points).

Figure 14. Evolution of the pore pressure excess (KN/m2) measured at an intermediate point of the infill alluvial layer (Level II). (a) All phases using a logarithmic scale (b) Enlargement of the construction (P3) and consolidation of the Alminar (P4).

Figure 15. Comparison between the real measurements of the verticality and the inclinations caused by the differential settlements.

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