OR/13/006 Geotechnical properties - Revision history

Ajhil: /* Consolidation */

2021-08-17T10:20:59Z

Consolidation

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	==Consolidation==		==Consolidation==
	Consolidation is the process whereby pore water is expelled from a soil as the result of applied, static, external stresses, resulting in structural densification of the soil. For most purposes, the external stress is considered to be unidirectional, and usually vertical. Swelling strain data may also be obtained from the oedometer test. The oedometer is a simple laboratory apparatus, which applies a vertical load to a small disc-shaped soil specimen, laterally confined in a ring. The consolidation test is normally carried out on undisturbed specimens by doubling the load at 24-hour intervals, and measuring the resulting consolidation deformation (BS1377: BSI, 1990; Head, 1998<ref name="Head 1998">HEAD, K H. 1998. ''Manual of soil laboratory testing: Effective stress tests. Volume 3''. Wiley Publishing.</ref>). This test is only suitable for fine-grained samples.		Consolidation is the process whereby pore water is expelled from a soil as the result of applied, static, external stresses, resulting in structural densification of the soil. For most purposes, the external stress is considered to be unidirectional, and usually vertical. Swelling strain data may also be obtained from the oedometer test. The oedometer is a simple laboratory apparatus, which applies a vertical load to a small disc-shaped soil specimen, laterally confined in a ring. The consolidation test is normally carried out on undisturbed specimens by doubling the load at 24-hour intervals, and measuring the resulting consolidation deformation (BS1377: BSI, 1990; Head, 1998<ref name="Head 1998">HEAD, K H. 1998. ''Manual of soil laboratory testing: Effective stress tests. Volume 3''. Wiley Publishing. </ref>). This test is only suitable for fine-grained samples.

	The ''rate'' at which the consolidation process takes place is characterised by the coefficient of consolidation, c<sub>v</sub>, and the ''amount'' of consolidation by the coefficient of volume compressibility, m<sub>v</sub>. Consolidation data derived from the oedometer test on undisturbed specimens are used in the calculation of likely foundation settlement, and may also provide information on the stress history, geological history, state of disturbance, permeability, and elastic moduli of clay soils.		The ''rate'' at which the consolidation process takes place is characterised by the coefficient of consolidation, c<sub>v</sub>, and the ''amount'' of consolidation by the coefficient of volume compressibility, m<sub>v</sub>. Consolidation data derived from the oedometer test on undisturbed specimens are used in the calculation of likely foundation settlement, and may also provide information on the stress history, geological history, state of disturbance, permeability, and elastic moduli of clay soils.

Ajhil: /* Undrained shear strength */

2021-08-17T10:20:20Z

Undrained shear strength

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	The 1,338 undrained cohesion (cu) values analysed show variable undrained strengths within the Lambeth Group. Median strength values range between 112 kPa and 164 kPa, with overall values ranging between c.10 kPa to over 800 kPa ,with the Reading Formation tending to have the highest and the Woolwich Formation the lowest values. The data show undrained strengths to be particularly variable in central London and Hight et al. (2004)<ref name="Hight 2004">HIGHT, D W, ELLISON, R A, and PAGE, D P. 2004. The engineering properties of the Lambeth Group. Report RP576 ''Construction Industry Research and Information Association (CIRIA)'', London.</ref> comment that the project-wide variability in undrained strength is similar to that found at a single location. This is the case for all formations and units.		The 1,338 undrained cohesion (cu) values analysed show variable undrained strengths within the Lambeth Group. Median strength values range between 112 kPa and 164 kPa, with overall values ranging between c.10 kPa to over 800 kPa ,with the Reading Formation tending to have the highest and the Woolwich Formation the lowest values. The data show undrained strengths to be particularly variable in central London and Hight et al. (2004)<ref name="Hight 2004">HIGHT, D W, ELLISON, R A, and PAGE, D P. 2004. The engineering properties of the Lambeth Group. Report RP576 ''Construction Industry Research and Information Association (CIRIA)'', London.</ref> comment that the project-wide variability in undrained strength is similar to that found at a single location. This is the case for all formations and units.

	The profile of Lambeth Group undrained strength values with depth (Figure 6.36) shows a great deal of scatter with an indistinct, trend of increasing strength with depth. Samples of extremely high strength and stronger (>300 kPa) occur near surface and increase in number with depth. There are also low strength samples at depth. In comparison to the Lambeth Group data, the undrained strength profile based on 2,100 data values for the London Clay Formation, from all areas, shows a clear overall trend of increasing strength with depth, but with generally less scatter of the data at all depths (Figure 6.37). The contrast between the Lambeth Group and the London Clay Formation results reflect the differences in their depositional environments and the post-depositional processes in particular pedogenic processes (cementing and fissuring) that affected some of the Lambeth Group deposits (Hight et al., 2004<ref name="Hight 2004"></ref>).		The profile of Lambeth Group undrained strength values with depth (Figure 6.36) shows a great deal of scatter with an indistinct, trend of increasing strength with depth. Samples of extremely high strength and stronger (>300 kPa) occur near surface and increase in number with depth. There are also low strength samples at depth. In comparison to the Lambeth Group data, the undrained strength profile based on 2,100 data values for the London Clay Formation, from all areas, shows a clear overall trend of increasing strength with depth, but with generally less scatter of the data at all depths (Figure 6.37). The contrast between the Lambeth Group and the London Clay Formation results reflect the differences in their depositional environments and the post-depositional processes in particular pedogenic processes (cementing and fissuring) that affected some of the Lambeth Group deposits (Hight et al., 2004<ref name="Hight 2004">HIGHT, D W, ELLISON, R A, and PAGE, D P. 2004. The engineering properties of the Lambeth Group. Report RP576 ''Construction Industry Research and Information Association (CIRIA)'', London.</ref>).

	[[Image:OR13006fig6.36.jpg\|thumb\|center\|700px\| '''Figure 6.36'''    Undrained shear strength profile for all Lambeth Group data, differentiated by formation. ]]		[[Image:OR13006fig6.36.jpg\|thumb\|center\|700px\| '''Figure 6.36'''    Undrained shear strength profile for all Lambeth Group data, differentiated by formation. ]]

Ajhil: /* Undrained shear strength */

2021-08-17T10:19:45Z

Undrained shear strength

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	Undrained (total) triaxial strength data are reported in site investigations either with the assumption that the friction angle,f, is zero, or that it has a positive value, despite this being contrary to the principles of the test (Head, 1992<ref name="Head 1992">HEAD, K H. 1992. ''Manual of soil laboratory testing: Permeability, shear strength and compressibility tests. Volume 2''. Pentach Press, UK. </ref>; Head, 1998<ref name="Head 1998">HEAD, K H. 1998. ''Manual of soil laboratory testing: Effective stress tests. Volume 3''. Wiley Publishing. </ref>). Undrained strength data containing a positive friction angle have been omitted from the database.		Undrained (total) triaxial strength data are reported in site investigations either with the assumption that the friction angle,f, is zero, or that it has a positive value, despite this being contrary to the principles of the test (Head, 1992<ref name="Head 1992">HEAD, K H. 1992. ''Manual of soil laboratory testing: Permeability, shear strength and compressibility tests. Volume 2''. Pentach Press, UK. </ref>; Head, 1998<ref name="Head 1998">HEAD, K H. 1998. ''Manual of soil laboratory testing: Effective stress tests. Volume 3''. Wiley Publishing. </ref>). Undrained strength data containing a positive friction angle have been omitted from the database.

	The 1,338 undrained cohesion (cu) values analysed show variable undrained strengths within the Lambeth Group. Median strength values range between 112 kPa and 164 kPa, with overall values ranging between c.10 kPa to over 800 kPa ,with the Reading Formation tending to have the highest and the Woolwich Formation the lowest values. The data show undrained strengths to be particularly variable in central London and Hight et al. (2004)<ref name="Hight 2004">HIGHT, D W, ELLISON, R A, and PAGE, D P. 2004. The engineering properties of the Lambeth Group. Report RP576 ''Construction Industry Research and Information Association (CIRIA)'', London. </ref> comment that the project-wide variability in undrained strength is similar to that found at a single location. This is the case for all formations and units.		The 1,338 undrained cohesion (cu) values analysed show variable undrained strengths within the Lambeth Group. Median strength values range between 112 kPa and 164 kPa, with overall values ranging between c.10 kPa to over 800 kPa ,with the Reading Formation tending to have the highest and the Woolwich Formation the lowest values. The data show undrained strengths to be particularly variable in central London and Hight et al. (2004)<ref name="Hight 2004">HIGHT, D W, ELLISON, R A, and PAGE, D P. 2004. The engineering properties of the Lambeth Group. Report RP576 ''Construction Industry Research and Information Association (CIRIA)'', London.</ref> comment that the project-wide variability in undrained strength is similar to that found at a single location. This is the case for all formations and units.

	The profile of Lambeth Group undrained strength values with depth (Figure 6.36) shows a great deal of scatter with an indistinct, trend of increasing strength with depth. Samples of extremely high strength and stronger (>300 kPa) occur near surface and increase in number with depth. There are also low strength samples at depth. In comparison to the Lambeth Group data, the undrained strength profile based on 2,100 data values for the London Clay Formation, from all areas, shows a clear overall trend of increasing strength with depth, but with generally less scatter of the data at all depths (Figure 6.37). The contrast between the Lambeth Group and the London Clay Formation results reflect the differences in their depositional environments and the post-depositional processes in particular pedogenic processes (cementing and fissuring) that affected some of the Lambeth Group deposits (Hight et al., 2004<ref name="Hight 2004"></ref>).		The profile of Lambeth Group undrained strength values with depth (Figure 6.36) shows a great deal of scatter with an indistinct, trend of increasing strength with depth. Samples of extremely high strength and stronger (>300 kPa) occur near surface and increase in number with depth. There are also low strength samples at depth. In comparison to the Lambeth Group data, the undrained strength profile based on 2,100 data values for the London Clay Formation, from all areas, shows a clear overall trend of increasing strength with depth, but with generally less scatter of the data at all depths (Figure 6.37). The contrast between the Lambeth Group and the London Clay Formation results reflect the differences in their depositional environments and the post-depositional processes in particular pedogenic processes (cementing and fissuring) that affected some of the Lambeth Group deposits (Hight et al., 2004<ref name="Hight 2004"></ref>).
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	[[Image:OR13006fig6.41.jpg\|thumb\|center\|700px\| '''Figure 6.41'''    Undrained shear strength of the Lambeth Group in Area 4 differentiated by lithostratigraphical unit. ]]		[[Image:OR13006fig6.41.jpg\|thumb\|center\|700px\| '''Figure 6.41'''    Undrained shear strength of the Lambeth Group in Area 4 differentiated by lithostratigraphical unit. ]]

	====Effective strength====		====Effective strength====
	Median effective strength data, (c´ and f´ values) for the Lambeth Group formations are shown in Table 6.7.		Median effective strength data, (c´ and f´ values) for the Lambeth Group formations are shown in Table 6.7.

Ajhil: /* Plasticity */

2021-08-17T10:19:02Z

Plasticity

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	Values of liquidity index may be used as a guide to desiccation or, where equilibrium water content is established, the degree of over-consolidation of a soil. A value of 0 indicates that the natural water content (w) equals the plastic limit (wP). A value of +1.00 indicates that the natural water content equals the liquid limit (wL). There are 2,591 liquidity indices for the Lambeth Group in the database. Values range from -0.6 to +0.86, with overall median and mean values of zero (that is, water contents are predominantly equal to the plastic limits). The median values of all the formations lie very close to zero. The liquidity index is variable near-surface depths because of seasonal changes in water content. The liquidity index profile for all the data, differentiated by formation and shown in Figure 6.19, tends to show a general trend of decreasing liquidity index with increasing depth. However, there are occasionally relatively high values at depth in samples from all formations, but particularly the Woolwich and Upnor formations. Low values occur near-surface but also at depth in all formations.		Values of liquidity index may be used as a guide to desiccation or, where equilibrium water content is established, the degree of over-consolidation of a soil. A value of 0 indicates that the natural water content (w) equals the plastic limit (wP). A value of +1.00 indicates that the natural water content equals the liquid limit (wL). There are 2,591 liquidity indices for the Lambeth Group in the database. Values range from -0.6 to +0.86, with overall median and mean values of zero (that is, water contents are predominantly equal to the plastic limits). The median values of all the formations lie very close to zero. The liquidity index is variable near-surface depths because of seasonal changes in water content. The liquidity index profile for all the data, differentiated by formation and shown in Figure 6.19, tends to show a general trend of decreasing liquidity index with increasing depth. However, there are occasionally relatively high values at depth in samples from all formations, but particularly the Woolwich and Upnor formations. Low values occur near-surface but also at depth in all formations.

	Liquidity indices for all data differentiated by area are shown in Figure 6.20, and for each area differentiated by lithostratigraphy (Figures 6.21 to 6.24). Area 1 (Figure 6.21) shows a general trend of reducing liquidity index with depth for the majority of the data but with a significant number of random higher or lower data points. Area 2 (Figure 6.22) shows little change in liquidity index with increasing depth. In this area the Reading Formation consists of the Lower Mottled Clay, which tends to be sandy, as does the Upnor Formation; the Lower Shelly Clay contains lignite, which tends to have a higher liquidity index. Areas 3 and 4 (Figure 6.23 and Figure 6.24) comprise the Upnor and Reading formations and show a weak trend of decreasing liquidity index with increasing depth. However, in both areas there are a number of low values in the Reading Formation and, in Area 3, high values in the Upnor Formation below 10 m. It has been suggested (Hight et al., 2004<ref name="Hight 2004"></ref>) that unusually high and low values may be spurious as a result of sample disturbance resulting in mixing of sands and clays (which may be the case for some parts of the Laminated Beds and the Upnor Formation), or redistribution of water during sampling. High liquidity index values are generally measured on cable percussion samples rather than on rotary core samples (Hight et al., 2004<ref name="Hight 2004"></ref>). However, some of the unusual values may be due to the variation in particle size where the sample has a large >0.425 mm component, the water content being measured on the whole sample and the plasticity being measured on part of the sample. This effect could be partly removed by correcting the plasticity values but the percentage of <0.425 mm particles has not been recorded in many cases. Also, the Reading Formation may have lower liquidity values due to its desiccation by pedological soil formation processes shortly after deposition.		Liquidity indices for all data differentiated by area are shown in Figure 6.20, and for each area differentiated by lithostratigraphy (Figures 6.21 to 6.24). Area 1 (Figure 6.21) shows a general trend of reducing liquidity index with depth for the majority of the data but with a significant number of random higher or lower data points. Area 2 (Figure 6.22) shows little change in liquidity index with increasing depth. In this area the Reading Formation consists of the Lower Mottled Clay, which tends to be sandy, as does the Upnor Formation; the Lower Shelly Clay contains lignite, which tends to have a higher liquidity index. Areas 3 and 4 (Figure 6.23 and Figure 6.24) comprise the Upnor and Reading formations and show a weak trend of decreasing liquidity index with increasing depth. However, in both areas there are a number of low values in the Reading Formation and, in Area 3, high values in the Upnor Formation below 10 m. It has been suggested (Hight et al., 2004<ref name="Hight 2004">HIGHT, D W, ELLISON, R A, and PAGE, D P. 2004. The engineering properties of the Lambeth Group. Report RP576 ''Construction Industry Research and Information Association (CIRIA)'', London.</ref>) that unusually high and low values may be spurious as a result of sample disturbance resulting in mixing of sands and clays (which may be the case for some parts of the Laminated Beds and the Upnor Formation), or redistribution of water during sampling. High liquidity index values are generally measured on cable percussion samples rather than on rotary core samples (Hight et al., 2004<ref name="Hight 2004">HIGHT, D W, ELLISON, R A, and PAGE, D P. 2004. The engineering properties of the Lambeth Group. Report RP576 ''Construction Industry Research and Information Association (CIRIA)'', London.</ref>). However, some of the unusual values may be due to the variation in particle size where the sample has a large >0.425 mm component, the water content being measured on the whole sample and the plasticity being measured on part of the sample. This effect could be partly removed by correcting the plasticity values but the percentage of <0.425 mm particles has not been recorded in many cases. Also, the Reading Formation may have lower liquidity values due to its desiccation by pedological soil formation processes shortly after deposition.

	[[Image:OR13006fig6.19.jpg\|thumb\|center\|700px\| '''Figure 6.19'''    Liquidity index profile for the Lambeth Group data, differentiated by Formation. ]]		[[Image:OR13006fig6.19.jpg\|thumb\|center\|700px\| '''Figure 6.19'''    Liquidity index profile for the Lambeth Group data, differentiated by Formation. ]]

Ajhil: /* Plasticity */

2021-08-17T10:18:04Z

Plasticity

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	A total of 2,769 plastic limits (wP %) and plasticity indices (IP = wL- wP) are in the database. The plasticity indices range from 2 to 92%, the overall median being 31%. Median values for the Upnor, Reading, and Woolwich formations are 23%, 36%, and 31%, respectively.		A total of 2,769 plastic limits (wP %) and plasticity indices (IP = wL- wP) are in the database. The plasticity indices range from 2 to 92%, the overall median being 31%. Median values for the Upnor, Reading, and Woolwich formations are 23%, 36%, and 31%, respectively.

	There is a wide range of plasticity values within the Lambeth Group, and within its formations. Overall, the data fall within the ‘low’ to the ‘extremely high’ range, although the great majority fall within the ‘low’ to ‘very high’ range. The clays of the Upper Mottled Clay tend to be of higher plasticity than those of the Lower Mottled Clay. The clay mineralogy of the Lower Mottled Clay and the Upnor Formation is sometimes dominated by the active clay mineral smectite, which suggests that they should have the higher plasticity. However, the Lower Mottled Clay and Upnor Formation contain significant silt and sand that tends to ‘dilute’, or reduce, the plasticity. In the Upnor Formation clays are often present in thin bands and retrieved samples are often mixed with coarser sandy material that results in lower plasticity determinations during laboratory testing. The Laminated Beds in Area 1 are generally more plastic than those in Area 2, probably because they contain more clay. The liquid limit of the Lower Shelly Clay in Area 2 is more variable than in Area 1 as Area 2 contains samples of lignite or highly organic clay, which have higher liquid limit values. Plasticity of the Upper and Lower Mottled Clays and Laminated Beds may increase towards the base. This is may be due to changes in clay mineralogy, and it has been considered that it may also be due to deposits coarsen upwards (Hight et al., 2004<ref name="Hight 2004"></ref>), however, the Upper and Lower Mottled Clays generally fine upwards.		There is a wide range of plasticity values within the Lambeth Group, and within its formations. Overall, the data fall within the ‘low’ to the ‘extremely high’ range, although the great majority fall within the ‘low’ to ‘very high’ range. The clays of the Upper Mottled Clay tend to be of higher plasticity than those of the Lower Mottled Clay. The clay mineralogy of the Lower Mottled Clay and the Upnor Formation is sometimes dominated by the active clay mineral smectite, which suggests that they should have the higher plasticity. However, the Lower Mottled Clay and Upnor Formation contain significant silt and sand that tends to ‘dilute’, or reduce, the plasticity. In the Upnor Formation clays are often present in thin bands and retrieved samples are often mixed with coarser sandy material that results in lower plasticity determinations during laboratory testing. The Laminated Beds in Area 1 are generally more plastic than those in Area 2, probably because they contain more clay. The liquid limit of the Lower Shelly Clay in Area 2 is more variable than in Area 1 as Area 2 contains samples of lignite or highly organic clay, which have higher liquid limit values. Plasticity of the Upper and Lower Mottled Clays and Laminated Beds may increase towards the base. This is may be due to changes in clay mineralogy, and it has been considered that it may also be due to deposits coarsen upwards (Hight et al., 2004<ref name="Hight 2004">HIGHT, D W, ELLISON, R A, and PAGE, D P. 2004. The engineering properties of the Lambeth Group. Report RP576 ''Construction Industry Research and Information Association (CIRIA)'', London.</ref>), however, the Upper and Lower Mottled Clays generally fine upwards.

	[[Image:OR13006fig6.13.jpg\|thumb\|center\|700px\| '''Figure 6.13'''    Plasticity chart for the Lambeth Group data differentiated by formation. ]]		[[Image:OR13006fig6.13.jpg\|thumb\|center\|700px\| '''Figure 6.13'''    Plasticity chart for the Lambeth Group data differentiated by formation. ]]

Ajhil: /* Water content and density */

2021-08-17T10:17:38Z

Water content and density

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	[[Image:OR13006fig6.6.jpg\|thumb\|center\|700px\| '''Figure 6.6'''    Natural water content profile differentiated by sample type, all data. ]]		[[Image:OR13006fig6.6.jpg\|thumb\|center\|700px\| '''Figure 6.6'''    Natural water content profile differentiated by sample type, all data. ]]

	The database contains 1,565 values for bulk density, r, (Mg/m<sup>3</sup>). This parameter may also be expressed as the total unit weight, g kN/m<sup>2</sup>, where g is equivalent to the bulk density multiplied by the acceleration due to gravity (9.807 m/s<sup>2</sup>). The values of bulk density vary between 1.43 Mg/m<sup>3</sup> and 2.375 Mg/m<sup>3</sup>, although most fall between 1.64 and 2.36 Mg/m<sup>3</sup>. The median values for the various formations are similar, lying in the range 2.04 to 2.08 Mg/m<sup>3</sup>, however, overall values may vary considerably locally, both vertically and laterally. The bulk density depth profile for all data differentiated by formation (Figure 6.7) shows a broad spread of values with a generally reduction in variation with depth as there is a reduction in lower bulk density with increasing depth. The London Clay Formation (Figure 6.8) shows a more consistent increase of density with depth. The Lambeth Group has many values between 2.0 Mg/m<sup>3</sup> and 2.2 Mg/m<sup>3</sup> at all depths particularly within the Reading Formation and the Upnor Formation. The scatter of the Lambeth Group data probably reflects changes due to depth but also lithology, pedogenic effects (including cementation) and other structural features. Whereas, scatter of data for the London Clay Formation is probably associated with depth, the different units within the formation and structural features. The comparison is crude being as the depth is from ground level without any information of units above but it does show the gross differences of the bulk density and depth relationship between the two units. Some low values may be the result of sample disturbance resulting in de-saturation due to stress relief (Hight et al., 2004<ref name="Hight 2004">HIGHT, D W, ELLISON, R A, and PAGE, D P. 2004. The engineering properties of the Lambeth Group. Report RP576 ''Construction Industry Research and Information Association (CIRIA)'', London.</ref>). Values of bulk density for the Upnor Formation, Lower Shelly Beds, and Laminated Beds may be unreliable due to sample disturbance (Hight et al., 2004<ref name="Hight 2004">HIGHT, D W, ELLISON, R A, and PAGE, D P. 2004. The engineering properties of the Lambeth Group. Report RP576 ''Construction Industry Research and Information Association (CIRIA)'', London.</ref>), for example where samples are taken by driven tube sampling that can readily disrupt the soil fabric leading to reduced density measurements that are not representative of the ''in situ'' state. The CIRIA report (Hight et al., 2004<ref name="Hight 2004"></ref>) states that values of less than 1.95 Mg/m<sup>3</sup> beneath central London should be treated with caution. The bulk density vs. depth profiles for each of the area locations recognised in this study are presented in Figure 6.7 to 6.12.		The database contains 1,565 values for bulk density, r, (Mg/m<sup>3</sup>). This parameter may also be expressed as the total unit weight, g kN/m<sup>2</sup>, where g is equivalent to the bulk density multiplied by the acceleration due to gravity (9.807 m/s<sup>2</sup>). The values of bulk density vary between 1.43 Mg/m<sup>3</sup> and 2.375 Mg/m<sup>3</sup>, although most fall between 1.64 and 2.36 Mg/m<sup>3</sup>. The median values for the various formations are similar, lying in the range 2.04 to 2.08 Mg/m<sup>3</sup>, however, overall values may vary considerably locally, both vertically and laterally. The bulk density depth profile for all data differentiated by formation (Figure 6.7) shows a broad spread of values with a generally reduction in variation with depth as there is a reduction in lower bulk density with increasing depth. The London Clay Formation (Figure 6.8) shows a more consistent increase of density with depth. The Lambeth Group has many values between 2.0 Mg/m<sup>3</sup> and 2.2 Mg/m<sup>3</sup> at all depths particularly within the Reading Formation and the Upnor Formation. The scatter of the Lambeth Group data probably reflects changes due to depth but also lithology, pedogenic effects (including cementation) and other structural features. Whereas, scatter of data for the London Clay Formation is probably associated with depth, the different units within the formation and structural features. The comparison is crude being as the depth is from ground level without any information of units above but it does show the gross differences of the bulk density and depth relationship between the two units. Some low values may be the result of sample disturbance resulting in de-saturation due to stress relief (Hight et al., 2004<ref name="Hight 2004">HIGHT, D W, ELLISON, R A, and PAGE, D P. 2004. The engineering properties of the Lambeth Group. Report RP576 ''Construction Industry Research and Information Association (CIRIA)'', London.</ref>). Values of bulk density for the Upnor Formation, Lower Shelly Beds, and Laminated Beds may be unreliable due to sample disturbance (Hight et al., 2004<ref name="Hight 2004">HIGHT, D W, ELLISON, R A, and PAGE, D P. 2004. The engineering properties of the Lambeth Group. Report RP576 ''Construction Industry Research and Information Association (CIRIA)'', London.</ref>), for example where samples are taken by driven tube sampling that can readily disrupt the soil fabric leading to reduced density measurements that are not representative of the ''in situ'' state. The CIRIA report (Hight et al., 2004<ref name="Hight 2004">HIGHT, D W, ELLISON, R A, and PAGE, D P. 2004. The engineering properties of the Lambeth Group. Report RP576 ''Construction Industry Research and Information Association (CIRIA)'', London.</ref>) states that values of less than 1.95 Mg/m<sup>3</sup> beneath central London should be treated with caution. The bulk density vs. depth profiles for each of the area locations recognised in this study are presented in Figure 6.7 to 6.12.

	[[Image:OR13006fig6.7.jpg\|thumb\|center\|700px\| '''Figure 6.7'''    Bulk density profile for the Lambeth Group data differentiated by Formation. ]]		[[Image:OR13006fig6.7.jpg\|thumb\|center\|700px\| '''Figure 6.7'''    Bulk density profile for the Lambeth Group data differentiated by Formation. ]]

Ajhil: /* Water content and density */

2021-08-17T10:17:06Z

Water content and density

← Older revision		Revision as of 11:17, 17 August 2021
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	[[Image:OR13006fig6.6.jpg\|thumb\|center\|700px\| '''Figure 6.6'''    Natural water content profile differentiated by sample type, all data. ]]		[[Image:OR13006fig6.6.jpg\|thumb\|center\|700px\| '''Figure 6.6'''    Natural water content profile differentiated by sample type, all data. ]]

	The database contains 1,565 values for bulk density, r, (Mg/m<sup>3</sup>). This parameter may also be expressed as the total unit weight, g kN/m<sup>2</sup>, where g is equivalent to the bulk density multiplied by the acceleration due to gravity (9.807 m/s<sup>2</sup>). The values of bulk density vary between 1.43 Mg/m<sup>3</sup> and 2.375 Mg/m<sup>3</sup>, although most fall between 1.64 and 2.36 Mg/m<sup>3</sup>. The median values for the various formations are similar, lying in the range 2.04 to 2.08 Mg/m<sup>3</sup>, however, overall values may vary considerably locally, both vertically and laterally. The bulk density depth profile for all data differentiated by formation (Figure 6.7) shows a broad spread of values with a generally reduction in variation with depth as there is a reduction in lower bulk density with increasing depth. The London Clay Formation (Figure 6.8) shows a more consistent increase of density with depth. The Lambeth Group has many values between 2.0 Mg/m<sup>3</sup> and 2.2 Mg/m<sup>3</sup> at all depths particularly within the Reading Formation and the Upnor Formation. The scatter of the Lambeth Group data probably reflects changes due to depth but also lithology, pedogenic effects (including cementation) and other structural features. Whereas, scatter of data for the London Clay Formation is probably associated with depth, the different units within the formation and structural features. The comparison is crude being as the depth is from ground level without any information of units above but it does show the gross differences of the bulk density and depth relationship between the two units. Some low values may be the result of sample disturbance resulting in de-saturation due to stress relief (Hight et al., 2004<ref name="Hight 2004">HIGHT, D W, ELLISON, R A, and PAGE, D P. 2004. The engineering properties of the Lambeth Group. Report RP576 ''Construction Industry Research and Information Association (CIRIA)'', London.</ref>). Values of bulk density for the Upnor Formation, Lower Shelly Beds, and Laminated Beds may be unreliable due to sample disturbance (Hight et al., 2004<ref name="Hight 2004"></ref>), for example where samples are taken by driven tube sampling that can readily disrupt the soil fabric leading to reduced density measurements that are not representative of the ''in situ'' state. The CIRIA report (Hight et al., 2004<ref name="Hight 2004"></ref>) states that values of less than 1.95 Mg/m<sup>3</sup> beneath central London should be treated with caution. The bulk density vs. depth profiles for each of the area locations recognised in this study are presented in Figure 6.7 to 6.12.		The database contains 1,565 values for bulk density, r, (Mg/m<sup>3</sup>). This parameter may also be expressed as the total unit weight, g kN/m<sup>2</sup>, where g is equivalent to the bulk density multiplied by the acceleration due to gravity (9.807 m/s<sup>2</sup>). The values of bulk density vary between 1.43 Mg/m<sup>3</sup> and 2.375 Mg/m<sup>3</sup>, although most fall between 1.64 and 2.36 Mg/m<sup>3</sup>. The median values for the various formations are similar, lying in the range 2.04 to 2.08 Mg/m<sup>3</sup>, however, overall values may vary considerably locally, both vertically and laterally. The bulk density depth profile for all data differentiated by formation (Figure 6.7) shows a broad spread of values with a generally reduction in variation with depth as there is a reduction in lower bulk density with increasing depth. The London Clay Formation (Figure 6.8) shows a more consistent increase of density with depth. The Lambeth Group has many values between 2.0 Mg/m<sup>3</sup> and 2.2 Mg/m<sup>3</sup> at all depths particularly within the Reading Formation and the Upnor Formation. The scatter of the Lambeth Group data probably reflects changes due to depth but also lithology, pedogenic effects (including cementation) and other structural features. Whereas, scatter of data for the London Clay Formation is probably associated with depth, the different units within the formation and structural features. The comparison is crude being as the depth is from ground level without any information of units above but it does show the gross differences of the bulk density and depth relationship between the two units. Some low values may be the result of sample disturbance resulting in de-saturation due to stress relief (Hight et al., 2004<ref name="Hight 2004">HIGHT, D W, ELLISON, R A, and PAGE, D P. 2004. The engineering properties of the Lambeth Group. Report RP576 ''Construction Industry Research and Information Association (CIRIA)'', London.</ref>). Values of bulk density for the Upnor Formation, Lower Shelly Beds, and Laminated Beds may be unreliable due to sample disturbance (Hight et al., 2004<ref name="Hight 2004">HIGHT, D W, ELLISON, R A, and PAGE, D P. 2004. The engineering properties of the Lambeth Group. Report RP576 ''Construction Industry Research and Information Association (CIRIA)'', London.</ref>), for example where samples are taken by driven tube sampling that can readily disrupt the soil fabric leading to reduced density measurements that are not representative of the ''in situ'' state. The CIRIA report (Hight et al., 2004<ref name="Hight 2004"></ref>) states that values of less than 1.95 Mg/m<sup>3</sup> beneath central London should be treated with caution. The bulk density vs. depth profiles for each of the area locations recognised in this study are presented in Figure 6.7 to 6.12.

	[[Image:OR13006fig6.7.jpg\|thumb\|center\|700px\| '''Figure 6.7'''    Bulk density profile for the Lambeth Group data differentiated by Formation. ]]		[[Image:OR13006fig6.7.jpg\|thumb\|center\|700px\| '''Figure 6.7'''    Bulk density profile for the Lambeth Group data differentiated by Formation. ]]

Ajhil: /* Standard Penetration Test (SPT) results */

2021-08-17T10:09:56Z

Standard Penetration Test (SPT) results

← Older revision		Revision as of 11:09, 17 August 2021
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	Figure 6.59 shows the SPT N value vs. depth profile for data from the 1:10k map sheet TQ38SE in east London, which area includes Hackney and Poplar, for Thanet Formation, Lambeth Group and London Clay Formation. The graph shows an increase in N-values with depth for the London Clay Formation, typically high values for the Thanet Formation and a large scatter of the Lambeth Group tests.		Figure 6.59 shows the SPT N value vs. depth profile for data from the 1:10k map sheet TQ38SE in east London, which area includes Hackney and Poplar, for Thanet Formation, Lambeth Group and London Clay Formation. The graph shows an increase in N-values with depth for the London Clay Formation, typically high values for the Thanet Formation and a large scatter of the Lambeth Group tests.

	[[Image:OR13006fig6.54.jpg\|thumb\|center\|~~500px~~\| '''Figure 6.54'''    Variation of SPT N-values with depth for the Lambeth Group by formation. ]]		[[Image:OR13006fig6.54.jpg\|thumb\|center\|700px\| '''Figure 6.54'''    Variation of SPT N-values with depth for the Lambeth Group by formation. ]]

	[[Image:OR13006fig6.55.jpg\|thumb\|center\|~~500px~~\| '''Figure 6.55'''    Variation of SPT N-values with depth for the Lambeth Group in Area 1 by unit. ]]		[[Image:OR13006fig6.55.jpg\|thumb\|center\|700px\| '''Figure 6.55'''    Variation of SPT N-values with depth for the Lambeth Group in Area 1 by unit. ]]

	[[Image:OR13006fig6.56.jpg\|thumb\|center\|~~500px~~\| '''Figure 6.56'''    Variation of SPT N-values with depth for the Lambeth Group in Area 2 by unit. ]]		[[Image:OR13006fig6.56.jpg\|thumb\|center\|700px\| '''Figure 6.56'''    Variation of SPT N-values with depth for the Lambeth Group in Area 2 by unit. ]]

	[[Image:OR13006fig6.57.jpg\|thumb\|center\|~~500px~~\| '''Figure 6.57'''    Variation of SPT N-values with depth for the Lambeth Group in Area 3 by formation. ]]		[[Image:OR13006fig6.57.jpg\|thumb\|center\|700px\| '''Figure 6.57'''    Variation of SPT N-values with depth for the Lambeth Group in Area 3 by formation. ]]

	[[Image:OR13006fig6.58.jpg\|thumb\|center\|~~500px~~\| '''Figure 6.58'''    Variation of SPT N-values with depth for the Lambeth Group in Area 4 by formation. ]]		[[Image:OR13006fig6.58.jpg\|thumb\|center\|700px\| '''Figure 6.58'''    Variation of SPT N-values with depth for the Lambeth Group in Area 4 by formation. ]]

	[[Image:OR13006fig6.59.jpg\|thumb\|center\|~~500px~~\| '''Figure 6.59'''    Variation of SPT N-values with depth for the Thanet Formation, Lambeth Group by unit and the London Clay Formation for data from TQ38SE. ]]		[[Image:OR13006fig6.59.jpg\|thumb\|center\|700px\| '''Figure 6.59'''    Variation of SPT N-values with depth for the Thanet Formation, Lambeth Group by unit and the London Clay Formation for data from TQ38SE. ]]

	==Brief summary of geotechnical properties==		==Brief summary of geotechnical properties==

Ajhil: /* Compaction, california bearing ratio and moisture condition value */

2021-08-17T10:05:22Z

Compaction, california bearing ratio and moisture condition value

← Older revision		Revision as of 11:05, 17 August 2021
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	Unusually, the vibro-compaction values are similar to light or heavy compactive effort results.		Unusually, the vibro-compaction values are similar to light or heavy compactive effort results.

	[[Image:OR13006fig6.51.jpg\|thumb\|center\|~~600px~~\| '''Figure 6.51'''    Optimum water content vs. maximum dry density showing different compactive efforts and lithologies. ]]		[[Image:OR13006fig6.51.jpg\|thumb\|center\|700px\| '''Figure 6.51'''    Optimum water content vs. maximum dry density showing different compactive efforts and lithologies. ]]

	===California bearing ratio===		===California bearing ratio===
	California bearing ratio is plotted against optimum water content and maximum dry density (Figure 6.52 and Figure 6.53 respectively). The two plots show a tendency of increase in CBR with decreasing optimum water content and increasing optimum dry density for each lithology.		California bearing ratio is plotted against optimum water content and maximum dry density (Figure 6.52 and Figure 6.53 respectively). The two plots show a tendency of increase in CBR with decreasing optimum water content and increasing optimum dry density for each lithology.

	[[Image:OR13006fig6.52.jpg\|thumb\|center\|~~600px~~\| '''Figure 6.52'''    Optimum water content vs. California bearing ratio for different compactive effort and lithology type. ]]		[[Image:OR13006fig6.52.jpg\|thumb\|center\|700px\| '''Figure 6.52'''    Optimum water content vs. California bearing ratio for different compactive effort and lithology type. ]]

	[[Image:OR13006fig6.53.jpg\|thumb\|center\|~~600px~~\| '''Figure 6.53'''    California bearing ratio vs. maximum dry density for different compactive effort and lithology type. ]]		[[Image:OR13006fig6.53.jpg\|thumb\|center\|700px\| '''Figure 6.53'''    California bearing ratio vs. maximum dry density for different compactive effort and lithology type. ]]
	===Moisture condition value===		===Moisture condition value===
	The moisture condition value (MCV) is a laboratory or field test, and is a means of selection, classification, and specification of fill material (BSI, 1990; Highways Agency, 1991<ref name="Highways Agency 1991">HIGHWAYS AGENCY. 1991. ''Specification for Highways Works''. HMSO. London. </ref>; Caprez and Honold, 1995<ref name="Caprez 1995">CAPREZ, M, and HONOLD, P. 1995. Moisture condition as a basis for compaction. ''Proceedings of the XI European Conference on Soil Mechanics and Foundation Engineering — The Interplay between Geotechnical Engineering and Engineering Geology'', Copenhagen, '''3''', 25–30 </ref>). The test aims to determine the minimum compactive effort required to produce near-full compaction of a 1.5 kg sample of soils passing a 20 mm sieve. The test differs from the traditional Proctor compaction test in that the compaction energy is applied across the entire sample surface, and compaction energy can be assessed as an independent variable. A total of 38 MCV data for Reading Formation Mottled Clays are contained in the database. The MCV values range from 0 to 18%, with a median of 9.3%. MCV values less than 7% tend to indicate very poor trafficability.		The moisture condition value (MCV) is a laboratory or field test, and is a means of selection, classification, and specification of fill material (BSI, 1990; Highways Agency, 1991<ref name="Highways Agency 1991">HIGHWAYS AGENCY. 1991. ''Specification for Highways Works''. HMSO. London. </ref>; Caprez and Honold, 1995<ref name="Caprez 1995">CAPREZ, M, and HONOLD, P. 1995. Moisture condition as a basis for compaction. ''Proceedings of the XI European Conference on Soil Mechanics and Foundation Engineering — The Interplay between Geotechnical Engineering and Engineering Geology'', Copenhagen, '''3''', 25–30 </ref>). The test aims to determine the minimum compactive effort required to produce near-full compaction of a 1.5 kg sample of soils passing a 20 mm sieve. The test differs from the traditional Proctor compaction test in that the compaction energy is applied across the entire sample surface, and compaction energy can be assessed as an independent variable. A total of 38 MCV data for Reading Formation Mottled Clays are contained in the database. The MCV values range from 0 to 18%, with a median of 9.3%. MCV values less than 7% tend to indicate very poor trafficability.

Ajhil: /* Compaction, california bearing ratio and moisture condition value */

2021-08-17T10:04:42Z

Compaction, california bearing ratio and moisture condition value

← Older revision		Revision as of 11:04, 17 August 2021
Line 1,092:		Line 1,092:
	Unusually, the vibro-compaction values are similar to light or heavy compactive effort results.		Unusually, the vibro-compaction values are similar to light or heavy compactive effort results.

	[[Image:OR13006fig6.51.jpg\|thumb\|center\|~~500px~~\| '''Figure 6.51'''    Optimum water content vs. maximum dry density showing different compactive efforts and lithologies. ]]		[[Image:OR13006fig6.51.jpg\|thumb\|center\|600px\| '''Figure 6.51'''    Optimum water content vs. maximum dry density showing different compactive efforts and lithologies. ]]

	===California bearing ratio===		===California bearing ratio===
	California bearing ratio is plotted against optimum water content and maximum dry density (Figure 6.52 and Figure 6.53 respectively). The two plots show a tendency of increase in CBR with decreasing optimum water content and increasing optimum dry density for each lithology.		California bearing ratio is plotted against optimum water content and maximum dry density (Figure 6.52 and Figure 6.53 respectively). The two plots show a tendency of increase in CBR with decreasing optimum water content and increasing optimum dry density for each lithology.

	[[Image:OR13006fig6.52.jpg\|thumb\|center\|~~500px~~\| '''Figure 6.52'''    Optimum water content vs. California bearing ratio for different compactive effort and lithology type. ]]		[[Image:OR13006fig6.52.jpg\|thumb\|center\|600px\| '''Figure 6.52'''    Optimum water content vs. California bearing ratio for different compactive effort and lithology type. ]]

	[[Image:OR13006fig6.53.jpg\|thumb\|center\|~~500px~~\| '''Figure 6.53'''    California bearing ratio vs. maximum dry density for different compactive effort and lithology type. ]]		[[Image:OR13006fig6.53.jpg\|thumb\|center\|600px\| '''Figure 6.53'''    California bearing ratio vs. maximum dry density for different compactive effort and lithology type. ]]
	===Moisture condition value===		===Moisture condition value===
	The moisture condition value (MCV) is a laboratory or field test, and is a means of selection, classification, and specification of fill material (BSI, 1990; Highways Agency, 1991<ref name="Highways Agency 1991">HIGHWAYS AGENCY. 1991. ''Specification for Highways Works''. HMSO. London. </ref>; Caprez and Honold, 1995<ref name="Caprez 1995">CAPREZ, M, and HONOLD, P. 1995. Moisture condition as a basis for compaction. ''Proceedings of the XI European Conference on Soil Mechanics and Foundation Engineering — The Interplay between Geotechnical Engineering and Engineering Geology'', Copenhagen, '''3''', 25–30 </ref>). The test aims to determine the minimum compactive effort required to produce near-full compaction of a 1.5 kg sample of soils passing a 20 mm sieve. The test differs from the traditional Proctor compaction test in that the compaction energy is applied across the entire sample surface, and compaction energy can be assessed as an independent variable. A total of 38 MCV data for Reading Formation Mottled Clays are contained in the database. The MCV values range from 0 to 18%, with a median of 9.3%. MCV values less than 7% tend to indicate very poor trafficability.		The moisture condition value (MCV) is a laboratory or field test, and is a means of selection, classification, and specification of fill material (BSI, 1990; Highways Agency, 1991<ref name="Highways Agency 1991">HIGHWAYS AGENCY. 1991. ''Specification for Highways Works''. HMSO. London. </ref>; Caprez and Honold, 1995<ref name="Caprez 1995">CAPREZ, M, and HONOLD, P. 1995. Moisture condition as a basis for compaction. ''Proceedings of the XI European Conference on Soil Mechanics and Foundation Engineering — The Interplay between Geotechnical Engineering and Engineering Geology'', Copenhagen, '''3''', 25–30 </ref>). The test aims to determine the minimum compactive effort required to produce near-full compaction of a 1.5 kg sample of soils passing a 20 mm sieve. The test differs from the traditional Proctor compaction test in that the compaction energy is applied across the entire sample surface, and compaction energy can be assessed as an independent variable. A total of 38 MCV data for Reading Formation Mottled Clays are contained in the database. The MCV values range from 0 to 18%, with a median of 9.3%. MCV values less than 7% tend to indicate very poor trafficability.

← Older revision		Revision as of 11:09, 17 August 2021
Line 1,299:		Line 1,299:
	Figure 6.59 shows the SPT N value vs. depth profile for data from the 1:10k map sheet TQ38SE in east London, which area includes Hackney and Poplar, for Thanet Formation, Lambeth Group and London Clay Formation. The graph shows an increase in N-values with depth for the London Clay Formation, typically high values for the Thanet Formation and a large scatter of the Lambeth Group tests.		Figure 6.59 shows the SPT N value vs. depth profile for data from the 1:10k map sheet TQ38SE in east London, which area includes Hackney and Poplar, for Thanet Formation, Lambeth Group and London Clay Formation. The graph shows an increase in N-values with depth for the London Clay Formation, typically high values for the Thanet Formation and a large scatter of the Lambeth Group tests.

	[[Image:OR13006fig6.54.jpg\|thumb\|center\|~~500px~~\| '''Figure 6.54'''    Variation of SPT N-values with depth for the Lambeth Group by formation. ]]		[[Image:OR13006fig6.54.jpg\|thumb\|center\|700px\| '''Figure 6.54'''    Variation of SPT N-values with depth for the Lambeth Group by formation. ]]

	[[Image:OR13006fig6.55.jpg\|thumb\|center\|~~500px~~\| '''Figure 6.55'''    Variation of SPT N-values with depth for the Lambeth Group in Area 1 by unit. ]]		[[Image:OR13006fig6.55.jpg\|thumb\|center\|700px\| '''Figure 6.55'''    Variation of SPT N-values with depth for the Lambeth Group in Area 1 by unit. ]]

	[[Image:OR13006fig6.56.jpg\|thumb\|center\|~~500px~~\| '''Figure 6.56'''    Variation of SPT N-values with depth for the Lambeth Group in Area 2 by unit. ]]		[[Image:OR13006fig6.56.jpg\|thumb\|center\|700px\| '''Figure 6.56'''    Variation of SPT N-values with depth for the Lambeth Group in Area 2 by unit. ]]

	[[Image:OR13006fig6.57.jpg\|thumb\|center\|~~500px~~\| '''Figure 6.57'''    Variation of SPT N-values with depth for the Lambeth Group in Area 3 by formation. ]]		[[Image:OR13006fig6.57.jpg\|thumb\|center\|700px\| '''Figure 6.57'''    Variation of SPT N-values with depth for the Lambeth Group in Area 3 by formation. ]]

	[[Image:OR13006fig6.58.jpg\|thumb\|center\|~~500px~~\| '''Figure 6.58'''    Variation of SPT N-values with depth for the Lambeth Group in Area 4 by formation. ]]		[[Image:OR13006fig6.58.jpg\|thumb\|center\|700px\| '''Figure 6.58'''    Variation of SPT N-values with depth for the Lambeth Group in Area 4 by formation. ]]

	[[Image:OR13006fig6.59.jpg\|thumb\|center\|~~500px~~\| '''Figure 6.59'''    Variation of SPT N-values with depth for the Thanet Formation, Lambeth Group by unit and the London Clay Formation for data from TQ38SE. ]]		[[Image:OR13006fig6.59.jpg\|thumb\|center\|700px\| '''Figure 6.59'''    Variation of SPT N-values with depth for the Thanet Formation, Lambeth Group by unit and the London Clay Formation for data from TQ38SE. ]]

	==Brief summary of geotechnical properties==		==Brief summary of geotechnical properties==