321.1 Design of Earth Slopes - Revision history

Smithk: /* 321.1.2.2 General Procedure for Slope Stability Analysis Using LRFD Approach */

2019-06-18T17:53:46Z

321.1.2.2 General Procedure for Slope Stability Analysis Using LRFD Approach

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	===321.1.2.2 General Procedure for Slope Stability Analysis Using LRFD Approach===		===321.1.2.2 General Procedure for Slope Stability Analysis Using LRFD Approach===
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	\|The procedure for design of earth slopes following LRFD is quite similar to procedures for conventional ASD analysis, with two important differences. The first difference occurs in No. 4, where factored parameters are used as input for the slope stability analyses for LRFD analyses whereas unfactored parameters are used for the traditional ASD analyses. The second difference occurs in No. 5, where instead of comparing the computed factor of safety to some required or target factor of safety as is done in ASD, the computed factor of safety is compared to a limit value (= 1.0) indicating stability or instability. In this respect, the LRFD procedure is indeed more straightforward than current procedures in that the analysis target or limit is consistent for all stability cases for the LRFD procedure whereas the analysis target for conventional ASD procedures varies from one application to another. The result of these differences is simply that, for LRFD procedures, uncertainties in the analyses are accounted for through factoring of the input parameters whereas for ASD procedures the uncertainty is accounted for through a single factor of safety. By factoring individual input parameters, it is possible to more appropriately apply conservatism to the individual parameters involved in the analysis, and therefore to effect more consistent levels of safety across a broad range of cases. Both load and resistance factors in LRFD and factors of safety in ASD are intended to account for uncertainties involved in the respective analyses. They are simply different methods for accounting for these uncertainties.		\|The procedure for design of earth slopes following LRFD is quite similar to procedures for conventional ASD analysis, with two important differences. The first difference occurs in No. 4, where factored parameters are used as input for the slope stability analyses for LRFD analyses whereas unfactored parameters are used for the traditional ASD analyses. The second difference occurs in No. 5, where instead of comparing the computed factor of safety to some required or target factor of safety as is done in ASD, the computed factor of safety is compared to a limit value (= 1.0) indicating stability or instability. In this respect, the LRFD procedure is indeed more straightforward than current procedures in that the analysis target or limit is consistent for all stability cases for the LRFD procedure whereas the analysis target for conventional ASD procedures varies from one application to another. The result of these differences is simply that, for LRFD procedures, uncertainties in the analyses are accounted for through factoring of the input parameters whereas for ASD procedures the uncertainty is accounted for through a single factor of safety. By factoring individual input parameters, it is possible to more appropriately apply conservatism to the individual parameters involved in the analysis, and therefore to effect more consistent levels of safety across a broad range of cases. Both load and resistance factors in LRFD and factors of safety in ASD are intended to account for uncertainties involved in the respective analyses. They are simply different methods for accounting for these uncertainties.
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	::c) If the factor of safety is less than 1.0, the designer must consider alternative measures to increase the factor of safety and repeat the procedure until a factor of safety approximately equal to 1.0 is achieved.		::c) If the factor of safety is less than 1.0, the designer must consider alternative measures to increase the factor of safety and repeat the procedure until a factor of safety approximately equal to 1.0 is achieved.

	Current procedures will factor the undrained shear strength, ''s<sub>u</sub>'', or the Mohr-Coulomb shear strength parameters, ''c'' and ''ϕ'' (or <math>\overline{c}</math> and <math> \overline{\phi}</math>). Resistance factors for factoring of these parameters are provided in EPG 321.1.2.4.		Current procedures will factor the undrained shear strength, ''s<sub>u</sub>'', or the Mohr-Coulomb shear strength parameters, ''c'' and ''ϕ'' (or <math>\overline{c}</math> and <math> \overline{\phi}</math>). Resistance factors for factoring of these parameters are provided in EPG 321.1.2.4.

	===321.1.2.3 Load Factors===		===321.1.2.3 Load Factors===

Smithk at 14:20, 9 January 2019

2019-01-09T14:20:16Z

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	\|[[media:321.1 MCHRP 75-1.pdf\|MCHRP 75-1, Strength and Drainage of a Rocky Residual Soil]]		\|[[media:321.1 MCHRP 75-1.pdf\|MCHRP 75-1, Strength and Drainage of a Rocky Residual Soil]]
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	\|[[media:203 MCHRP 76-1.pdf\|MCHRP 76-1, Evaluation of a One-Point Compaction Test for Missouri Soils]]		\|[[media:203 MCHRP 76-1a.pdf\|MCHRP 76-1, Evaluation of a One-Point Compaction Test for Missouri Soils]]
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	\|[[media:321.1 MCHRP 79-1.pdf\|MCHRP 79-1, Engineering Properties of Three Problem Earth Materials]]		\|[[media:321.1 MCHRP 79-1.pdf\|MCHRP 79-1, Engineering Properties of Three Problem Earth Materials]]
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	\|[[media:203 Physical Studies of Pennsylvanian Shale in a High ~~Fill~~.pdf\|Physical Studies of Pennsylvanian Shale in a High Fill]]		\|[[media:203 Physical Studies of Pennsylvanian Shale in a High Filla.pdf\|Physical Studies of Pennsylvanian Shale in a High Fill]]
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	\|[[media:321.1 Procedures for Design of Earth Slopes.pdf\|Procedures for Design of Earth Slopes Using LRFD]]		\|[[media:321.1 Procedures for Design of Earth Slopes.pdf\|Procedures for Design of Earth Slopes Using LRFD]]

EPGsysop at 18:43, 7 April 2017

2017-04-07T18:43:25Z

← Older revision		Revision as of 13:43, 7 April 2017
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	\|These boxes will provide supplemental information or commentary on application of specific provisions, supporting documentation for the provisions, or explanations for how the provisions should be applied.		\|These boxes will provide supplemental information or commentary on application of specific provisions, supporting documentation for the provisions, or explanations for how the provisions should be applied.
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	This article provides requirements for design of earth slopes commonly encountered in transportation rights of way. Such slopes commonly include embankment slopes for fills and bridge approaches and excavated slopes in cut sections of roadway. Earth slopes should be designed to maintain stability for conditions and loads that can reasonably be expected to be encountered throughout the life of the slope based on available information regarding site conditions and anticipated loadings. Earth slopes should also be designed ~~such~~ that excessive deformations are not experienced throughout the life of the structure or so that deformations that do occur do not adversely affect the travel way.		This article provides requirements for design of earth slopes commonly encountered in transportation rights of way. Such slopes commonly include embankment slopes for fills and bridge approaches and excavated slopes in cut sections of roadway. Earth slopes should be designed to maintain stability for conditions and loads that can reasonably be expected to be encountered throughout the life of the slope based on available information regarding site conditions and anticipated loadings. Earth slopes should also be designed so that excessive deformations are not experienced throughout the life of the structure or so that deformations that do occur do not adversely affect the travel way.
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	\|It should be emphasized that this chart is a guide. It is based on some theory and it is tempered by experience. It fits most situations, but there are exceptions. Some of the exceptions have been addressed in research reports. For the most part, this chart is based on stability considerations, but in one area it is been shaded a bit for erosion control purposes. This is for the ML loesses. When dealing with a very tight right of way situation, it may be practical to steepen slopes in this material to 1V:2H (2:1) at the expense of some increased erosion problems or erosion control measures. If in doubt, shear tests can be done. To repeat, this chart is a guide - it is not carved in stone.		\|It should be emphasized that this chart is a guide. It is based on some theory and it is tempered by experience. It fits most situations, but there are exceptions. Some of the exceptions have been addressed in research reports. For the most part, this chart is based on stability considerations, but in one area it is been shaded a bit for erosion control purposes. This is for the ML loesses. When dealing with a very tight right of way situation, it may be practical to steepen slopes in this material to 1V:2H (2:1) at the expense of some increased erosion problems or erosion control measures. If in doubt, shear tests can be done. To repeat, this chart is a guide - it is not carved in stone.
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	\|For grade separations, consideration should be given to selective grading of fill materials ~~such~~ that better materials are placed in fill spill slopes (i.e. beneath bridge abutments) so that the spill slopes can be steepened. While such handling will likely increase costs for fill placement, some additional handling can be justified if it results in reducing bridge length. Selective fill placement is not generally practical on stream crossings -- only on grade separations.		\|For grade separations, consideration should be given to selective grading of fill materials so that better materials are placed in fill spill slopes (i.e. beneath bridge abutments) so that the spill slopes can be steepened. While such handling will likely increase costs for fill placement, some additional handling can be justified if it results in reducing bridge length. Selective fill placement is not generally practical on stream crossings -- only on grade separations.
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	\|Table 321.1 permits spill slopes to be 1V:0.5H (0.5:1) steeper than side slopes for several soil types, but no steeper than 1V:2H (2:1), where the elevation differential between the toe of slope and grade at the bridge end is less than 20 feet. This recognizes the fact that the effective height of the spill slope will be reduced by at least 6 to 8 ft. because of the abutment headwall. This concept becomes more complicated at stream channel crossings where it is necessary to consider the depth and condition of the stream channel and their effect on bridge end location. For example, one might have CL glacial soils and a height differential between grade and toe of slope of some 15 feet. Table 321.1 requries 1V:2.5H (2.5:1) side slopes and 1V:2H (2:1) spill slopes for CL fill soils. However, if the stream channel is entrenched in CL soil another 15 feet deep ~~such~~ that the total height differential is greater than 20 feet, the bridge ends should be stepped back to or beyond a point determined by projecting a 1V:2.5H (2.5:1) upward from the toe of the channel slope to intersection with grade. For typically steep channel banks, this will generally leave a substantial bench at natural ground level, which provides some room for bank sloughing without affecting the integrity of the spill slope. The spill slope would remain at 1V:2H (2:1) but the bridge end would be located as if it were at least 1V:2.5H (2.5:1).		\|Table 321.1 permits spill slopes to be 1V:0.5H (0.5:1) steeper than side slopes for several soil types, but no steeper than 1V:2H (2:1), where the elevation differential between the toe of slope and grade at the bridge end is less than 20 feet. This recognizes the fact that the effective height of the spill slope will be reduced by at least 6 to 8 ft. because of the abutment headwall. This concept becomes more complicated at stream channel crossings where it is necessary to consider the depth and condition of the stream channel and their effect on bridge end location. For example, one might have CL glacial soils and a height differential between grade and toe of slope of some 15 feet. Table 321.1 requries 1V:2.5H (2.5:1) side slopes and 1V:2H (2:1) spill slopes for CL fill soils. However, if the stream channel is entrenched in CL soil another 15 feet deep so that the total height differential is greater than 20 feet, the bridge ends should be stepped back to or beyond a point determined by projecting a 1V:2.5H (2.5:1) upward from the toe of the channel slope to intersection with grade. For typically steep channel banks, this will generally leave a substantial bench at natural ground level, which provides some room for bank sloughing without affecting the integrity of the spill slope. The spill slope would remain at 1V:2H (2:1) but the bridge end would be located as if it were at least 1V:2.5H (2.5:1).
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	\|Now things get even more complicated. To this point, we have not really considered some of the possible complications to the stability of stream and channel slopes. There is a caution in the text beneath the slope selection chart that, "Factors such as foundations, seepage, susceptibility to inundation, etc. may dictate flatter slopes." Even ignoring foundations, which call for a special investigation, there is no simple way of considering the effects of water that will fit every case. Determining proper slopes in such circumstances involves consideration of a complex intermingling of factors such as flooding rate, height and duration, rate of recession, water velocity, scour potential, soil strength, weight, permeability, swell potential, and seepage rates, all further complicated by considerations of costs and the risks and consequences of failure.		\|Now things get even more complicated. To this point, we have not really considered some of the possible complications to the stability of stream and channel slopes. There is a caution in the text beneath the slope selection chart that, "Factors such as foundations, seepage, susceptibility to inundation, etc. may dictate flatter slopes." Even ignoring foundations, which call for a special investigation, there is no simple way of considering the effects of water that will fit every case. Determining proper slopes in such circumstances involves consideration of a complex intermingling of factors such as flooding rate, height and duration, rate of recession, water velocity, scour potential, soil strength, weight, permeability, swell potential, and seepage rates, all further complicated by considerations of costs and the risks and consequences of failure.

Smithk: /* 321.1.2.3 Load Factors */

2013-09-05T19:52:09Z

321.1.2.3 Load Factors

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	\|Despite the fact that stability is really a strength limit state, load factors associated with the Service I limit state are used for all loads by convention with current AASHTO LRFD procedures. This position makes some sense when considering earth loads that often have little variability and uncertainty, but may not make sense when stability is dominated by loading from bridge or other structures.		\|Despite the fact that stability is really a strength limit state, load factors associated with the Service I limit state are used for all loads by convention with current AASHTO LRFD procedures. This position makes some sense when considering earth loads that often have little variability and uncertainty, but may not make sense when stability is dominated by loading from bridge or other structures.
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	Loads to be used for stability evaluations shall be factored according to the Service I limit state. Accordingly, a load factor of 1.0 shall be used for all applied loads, including “surcharge” loads associated with foundations or other surface loads. The soil unit weight shall also be factored using a load factor of 1.0.		Loads to be used for stability evaluations shall be factored according to the Service I limit state.
	~~<div id="321.1.2.4 Resistance factors"></div>~~		<div id="Accordingly, a load factor of 1.0"></div>
			Accordingly, a load factor of 1.0 shall be used for all applied loads, including “surcharge” loads associated with foundations or other surface loads. The soil unit weight shall also be factored using a load factor of 1.0.

	===321.1.2.4 Resistance factors for short-term, undrained conditions===		===321.1.2.4 Resistance factors for short-term, undrained conditions===

Smithk: /* 321.1.2.3 Load Factors */

2013-09-05T19:51:05Z

321.1.2.3 Load Factors

← Older revision		Revision as of 14:51, 5 September 2013
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	\|Despite the fact that stability is really a strength limit state, load factors associated with the Service I limit state are used for all loads by convention with current AASHTO LRFD procedures. This position makes some sense when considering earth loads that often have little variability and uncertainty, but may not make sense when stability is dominated by loading from bridge or other structures.		\|Despite the fact that stability is really a strength limit state, load factors associated with the Service I limit state are used for all loads by convention with current AASHTO LRFD procedures. This position makes some sense when considering earth loads that often have little variability and uncertainty, but may not make sense when stability is dominated by loading from bridge or other structures.
	\|}		\|}
	Loads to be used for stability evaluations shall be factored according to the Service I limit state. Accordingly, a load factor of 1.0 shall be used for all applied loads, including “surcharge” loads associated with foundations or other surface loads. The soil unit weight shall also be factored using a<div id="~~load factor of~~ 1.0"></div> ~~load factor of 1.0.~~		Loads to be used for stability evaluations shall be factored according to the Service I limit state. Accordingly, a load factor of 1.0 shall be used for all applied loads, including “surcharge” loads associated with foundations or other surface loads. The soil unit weight shall also be factored using a load factor of 1.0.
			<div id="321.1.2.4 Resistance factors"></div>

	===321.1.2.4 Resistance factors for short-term, undrained conditions===		===321.1.2.4 Resistance factors for short-term, undrained conditions===

Smithk: /* 321.1.2.3 Load Factors */

2013-09-05T19:47:23Z

321.1.2.3 Load Factors

← Older revision		Revision as of 14:47, 5 September 2013
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	\|Despite the fact that stability is really a strength limit state, load factors associated with the Service I limit state are used for all loads by convention with current AASHTO LRFD procedures. This position makes some sense when considering earth loads that often have little variability and uncertainty, but may not make sense when stability is dominated by loading from bridge or other structures.		\|Despite the fact that stability is really a strength limit state, load factors associated with the Service I limit state are used for all loads by convention with current AASHTO LRFD procedures. This position makes some sense when considering earth loads that often have little variability and uncertainty, but may not make sense when stability is dominated by loading from bridge or other structures.
	\|}		\|}
	Loads to be used for stability evaluations shall be factored according to the Service I limit state. Accordingly, a load factor of 1.0 shall be used for all applied loads, including “surcharge” loads associated with foundations or other surface loads. The soil unit weight shall also be factored using a ~~load factor of 1.0.~~		Loads to be used for stability evaluations shall be factored according to the Service I limit state. Accordingly, a load factor of 1.0 shall be used for all applied loads, including “surcharge” loads associated with foundations or other surface loads. The soil unit weight shall also be factored using a<div id="load factor of 1.0"></div> load factor of 1.0.
	<div id="~~321.~~1.~~2.4 Resistance factors for short-term, undrained~~"></div>

	===321.1.2.4 Resistance factors for short-term, undrained conditions===		===321.1.2.4 Resistance factors for short-term, undrained conditions===

Smithk: /* 321.1.2 Slope Stability Analyses for Special Foundation Investigations */

2013-09-05T19:37:39Z

321.1.2 Slope Stability Analyses for Special Foundation Investigations

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	Loads to be used for stability evaluations shall be factored according to the Service I limit state. Accordingly, a load factor of 1.0 shall be used for all applied loads, including “surcharge” loads associated with foundations or other surface loads. The soil unit weight shall also be factored using a load factor of 1.0.		Loads to be used for stability evaluations shall be factored according to the Service I limit state. Accordingly, a load factor of 1.0 shall be used for all applied loads, including “surcharge” loads associated with foundations or other surface loads. The soil unit weight shall also be factored using a load factor of 1.0.
			<div id="321.1.2.4 Resistance factors for short-term, undrained"></div>

	===321.1.2.4 Resistance factors for short-term, undrained conditions===		===321.1.2.4 Resistance factors for short-term, undrained conditions===

Smithk: Per Geotechnical, clarifications and corrections

2012-07-30T12:36:54Z

Per Geotechnical, clarifications and corrections

← Older revision		Revision as of 07:36, 30 July 2012
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	where <math>c^\star</math> and tan''ϕ<sup>*</sup>'' are respectively the factored intercept and slope of the Mohr-Coulomb failure envelope, ''c'' and tan''ϕ'' are respectively the nominal intercept and slope of the Mohr-Coulomb failure envelope, and ''ϕ<sub>ss</sub>'' is the resistance factor determined from Figure 321.1.2.4 for the appropriate value of ''λ<sub>cϕ</sub>''. ''Note that it is the tangent of the friction angle that is factored rather than the friction angle itself.''		where <math>c^\star</math> and tan''ϕ<sup>*</sup>'' are respectively the factored intercept and slope of the Mohr-Coulomb failure envelope, ''c'' and tan''ϕ'' are respectively the nominal intercept and slope of the Mohr-Coulomb failure envelope, and ''ϕ<sub>ss</sub>'' is the resistance factor determined from Figure 321.1.2.4 for the appropriate value of ''λ<sub>cϕ</sub>'' and COV of Shear Strength Parameter, COV<sub>ss</sub>, as determined in accordance with [[321.3 Procedures for Estimation of Geotechnical Parameter Values and Coefficients of Variation\|EPG 321.3]]. ''Note that it is the tangent of the friction angle that is factored rather than the friction angle itself.''

	[[image:321.1.2.4.jpg\|center\|750px\|thumb\|<center>'''Fig. 321.1.2.4 Resistance factors for shear strength parameters for stability analysis of short-term, undrained conditions.'''</center>]]		[[image:321.1.2.4.jpg\|center\|750px\|thumb\|<center>'''Fig. 321.1.2.4 Resistance factors for shear strength parameters for stability analysis of short-term, undrained conditions.'''</center>]]
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	where <math>\overline{c}^\star</math> and <math>\tan\overline{\phi}^\star</math> are respectively the factored intercept and slope of the Mohr-Coulomb failure envelope, <math>\overline{c}</math> and <math>\tan\overline{\phi}</math> are respectively the nominal intercept and slope of the Mohr-Coulomb failure envelope established in terms of effective stresses, and ''ϕ<sub>ss</sub>'' is the resistance factor determined from Figure 321.1.2.4 for the appropriate value of ''λ<sub>cϕ</sub>''. ''Note that it is the tangent of the friction angle that is factored rather than the friction angle itself.''		where <math>\overline{c}^\star</math> and <math>\tan\overline{\phi}^\star</math> are respectively the factored intercept and slope of the Mohr-Coulomb failure envelope, <math>\overline{c}</math> and <math>\tan\overline{\phi}</math> are respectively the nominal intercept and slope of the Mohr-Coulomb failure envelope established in terms of effective stresses, and ''ϕ<sub>ss</sub>'' is the resistance factor determined from Figure 321.1.2.5 for the appropriate value of ''λ<sub>cϕ</sub>'' and COV of Shear Strength Parameter, COV<sub>ss</sub>, as determined in accordance with [[321.3 Procedures for Estimation of Geotechnical Parameter Values and Coefficients of Variation\|EPG 321.3]]. ''Note that it is the tangent of the friction angle that is factored rather than the friction angle itself.''

	[[image:321.1.2.5.jpg\|center\|750px\|thumb\|<center>'''Fig. 321.1.2.5 Resistance factors for shear strength parameters for stability analysis of ~~short~~-term, ~~undrained~~ conditions.'''</center>]]		[[image:321.1.2.5.jpg\|center\|750px\|thumb\|<center>'''Fig. 321.1.2.5 Resistance factors for shear strength parameters for stability analysis of long-term, drained conditions.'''</center>]]

	Pore pressure conditions, which may be represented in a number of different ways for stability analyses (e.g. piezometric lines, pore pressure ratio, etc.), should be selected using all available information as well as sound judgment, just as it would be following traditional ASD analysis methods. It is important that the pore pressure conditions used reflect the worst-case pore pressure conditions anticipated over the life of the slope.		Pore pressure conditions, which may be represented in a number of different ways for stability analyses (e.g. piezometric lines, pore pressure ratio, etc.), should be selected using all available information as well as sound judgment, just as it would be following traditional ASD analysis methods. It is important that the pore pressure conditions used reflect the worst-case pore pressure conditions anticipated over the life of the slope.

Smithk: Per CM, added "Procedures for Design of Earth Slopes Using LRFD'' report.

2012-01-25T19:47:35Z

Per CM, added "Procedures for Design of Earth Slopes Using LRFD'' report.

Smithk: New article. FHWA mandates that all bridges and foundations be designed in accordance with LRFD Bridge Design specs.

2011-03-31T19:52:44Z

New article. FHWA mandates that all bridges and foundations be designed in accordance with LRFD Bridge Design specs.

Show changes

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	{\|style="padding: 0.3em; margin-left:10px; border:1px solid #ff0000; text-align:left; font-size: 95%; background:#f5f5f5" width="~~350px~~" align="right"		{\|style="padding: 0.3em; margin-left:10px; border:1px solid #ff0000; text-align:left; font-size: 95%; background:#f5f5f5" width="385px" align="right"
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	\|align="center"\|'''Commentary Boxes'''		\|align="center"\|'''Commentary Boxes'''
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	This article provides requirements for design of earth slopes commonly encountered in transportation rights of way. Such slopes commonly include embankment slopes for fills and bridge approaches and excavated slopes in cut sections of roadway. Earth slopes should be designed to maintain stability for conditions and loads that can reasonably be expected to be encountered throughout the life of the slope based on available information regarding site conditions and anticipated loadings. Earth slopes should also be designed such that excessive deformations are not experienced throughout the life of the structure or so that deformations that do occur do not adversely affect the travel way.		This article provides requirements for design of earth slopes commonly encountered in transportation rights of way. Such slopes commonly include embankment slopes for fills and bridge approaches and excavated slopes in cut sections of roadway. Earth slopes should be designed to maintain stability for conditions and loads that can reasonably be expected to be encountered throughout the life of the slope based on available information regarding site conditions and anticipated loadings. Earth slopes should also be designed such that excessive deformations are not experienced throughout the life of the structure or so that deformations that do occur do not adversely affect the travel way.
	{\|style="padding: 0.3em; margin-left:7px; border:2px solid #a9a9a9; text-align:left; font-size: 95%; background:#f5f5f5" width="~~350px~~" align="right"		{\|style="padding: 0.3em; margin-left:7px; border:2px solid #a9a9a9; text-align:left; font-size: 95%; background:#f5f5f5" width="385px" align="right"
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	\|<center>'''Additional Information'''</center>		\|<center>'''Additional Information'''</center>
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	\|[[media:203 Physical Studies of Pennsylvanian Shale in a High Fill.pdf\|Physical Studies of Pennsylvanian Shale in a High Fill]]		\|[[media:203 Physical Studies of Pennsylvanian Shale in a High Fill.pdf\|Physical Studies of Pennsylvanian Shale in a High Fill]]
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			\|[[media:321.1 Procedures for Design of Earth Slopes.pdf\|Procedures for Design of Earth Slopes Using LRFD]]
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	In the context of these guidelines, “design” of earth slopes generally involves selection of some combination of the following to produce a final slope that will satisfy performance requirements:		In the context of these guidelines, “design” of earth slopes generally involves selection of some combination of the following to produce a final slope that will satisfy performance requirements:
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	For any given slope, some of these parameters will be constrained to satisfy site or project specific requirements so the specific parameters that can be varied to produce acceptable performance will be case dependent.		For any given slope, some of these parameters will be constrained to satisfy site or project specific requirements so the specific parameters that can be varied to produce acceptable performance will be case dependent.
	{\|style="padding: 0.3em; margin-left:10px; border:1px solid #ff0000; text-align:left; font-size: 95%; background:#f5f5f5" width="~~350px~~" align="right"		{\|style="padding: 0.3em; margin-left:10px; border:1px solid #ff0000; text-align:left; font-size: 95%; background:#f5f5f5" width="385px" align="right"
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	\|The provisions of [[#321.1.2 Slope Stability Analyses for Special Foundation Investigations\|EPG 321.1.2]] and [[#321.1.3 Serviceability\|EPG 321.1.3]] shall be followed for site/location specific stability analyses and for overall stability evaluations for retaining walls and spread footings.		\|The provisions of [[#321.1.2 Slope Stability Analyses for Special Foundation Investigations\|EPG 321.1.2]] and [[#321.1.3 Serviceability\|EPG 321.1.3]] shall be followed for site/location specific stability analyses and for overall stability evaluations for retaining walls and spread footings.