5 Earth Works
5.1 Excavation
5.1.1 When excavating trenches（pits），if buried things were discovered（especially cultural relics，ancient tombs，etc.），construction work must be stopped immediately，and the site shall be protected.It is prohibited from continuing construction within the section of this area before the situation has been properly handled.
5.1.2 The pole holes shall meet the following requirements:
1 The hole depth shall comply with the standards listed in Table 5.1.2，allowable deviation of hole depth is 50mm.To measure depth of pole holes surrounded by temporarily piledup soil covering the surface，permanent ground surface shall be taken as starting point of measurement.
2 The depth of holes on slopes shall be calculated from the points 150mm-200mm below the downslope grooves（Figure 5.1.2）.
3 The bottom of pole holes shall be flat.
Table 5.1.2 Standard Depth of Overhead Optical（Electrical）Cable Poles
Notes:1 The hole depth of special poles greater than 12m shall comply with design documents；
2 This table is applicable to the newly-built communications lines in areas with light and medium loads.The hole depth in heavy-load areas shall be increased by 100mm-200mm on the basis of the values specified in this table；
3 The hole depth of bracing pole shall not be less than 0.6m.The design requirement shall be followed for special cases.
4 The hole depth for stay-pile pole shall meet the following requirements:
1）The hole depth shall be not less than 1.2m in normal soil，hard soil or gravel soil area；
2）The hole depth shall be not less than 0.8m in stony soil.
Figure 5.1.2 Approach to Measure the Depth of Pole Holes on Slopes
1—Standard Hole Depth of the Slope；2—The Depth Measured on the Slope
5.1.3 The depth of anchor pit shall comply with the following requirements:
1 Pit depth shall comply with Table 5.1.3，allowable deviation is 50mm.
Table 5.1.3 Depth of anchor pits
2 Pit depth of suspended stay wire shall be 0.2m-0.3m deeper than that of ground stay wire.
3 Hole depth of bracing pole shall not be shorter than 600mm.
Pit bottom shall be flat，the notch slop must be consistent with stay wire angle，and the slope surface shall be smooth.
4 Hole depth of high stake stay wire shall meet the following requirements:
1）When assistant stay wire is needed in addition of high stake stay wire，hole depth of stake shall not be shorter than 1200mm，hole depth of stake in stony soil shall not be shorter than 800mm.
2）When assistant stay wire is not needed，hole depth of stake shall be the same as that of poles.
5 Pit depth of suspended stay wire shall be 200mm-300mm greater than that of ground stay wire.
5.1.4 The trenches of optical（electrical）cables and silicon-core plastic pipes shall meet the following requirements:
1 Trenches shall be straight withoutsnaky bending；trench bed shall be flat，and slopes of trenches and trench bed shall be slowly extending.
2 Smooth transition at ridges shall be kept for trenches of silicon-core plastic pipe，and bending radius of silicon-core plastic pipe around corner shall comply with the provisions of Section 7.1.6.
3 Road surface and stones excavatedduring construction shall be piled up separately from soil.Stone markers of other optical（electrical）cables and fire hydrants must not be covered by earth and soil excavated.
4 When digging trenches by blasting on stony ground，the width of trench bottom shall not be less than 200mm，and 100mm thick fine soil or sandysoil shall be placed on stony trench bottom.
5 When trenches of optical（electrical）cable and silicon-core pipes pass through moving sand zones，cables and pipes shall be laid in a timely manner to prevent cave-in.In case of serious cave-in，excavation and laying shall be carried out simultaneously.
6 When laying silicon-core pipes in shoulders and isolation strips of expressways，elevation data given by design and road authority shall be checked and verified.
5.1.5 The burial depth of direct-buried optical（electrical）cable shall comply with the requirements in Table 5.1.5.
Table 5.1.5 Burial depth of direct-buried optical（electrical）cable
Notes:1 Design depth in roadside ditches shall be the depth required by road or urban construction administration.Depth of stony roadside ditches that are ditched manually can be reduced to 0.4m，but the ditches shall be sealed with anti-wash materials such as cement mortar.
2 100mm thick fine soil or sandy soil shall be laid on ditch bottoms in stony and semi-stony sections.
3 The requirements for burial depth in frozenearth are not included in the above table，those burial depths shall comply with engineering design requirements.
5.1.6 The burial depth of silicon-core pipes shall comply with Table 5.1.6.
Table 5.1.6 Burial depth of silicon-core pipes
Table 5.1.6（Continued）
Notes:1 The burial depth of stony ditches that are ditched manually and road（railway）side ditches can be reduced to 0.4m，and the ditches shall be sealed with anti-wash materials such as cement mortar in accordance with the design requirements.The burial depth for hard road shoulders can be reduced to 0.6m.
2 The bottom width of pipe trenches usually shall be 100m greater than each side of pipe group arrangement and each side is no less than 0.1m.
3 When excavating pipe trenches in central isolation zone or highway roadshoulder，the impact of installing crash barriers on silicon-core pipes shall be taken into account in determining the burial depth and pipe arrangement width.
5.1.7 The standard burial depth of underwater optical（electrical）cables shall comply with Table 5.1.7.
Table 5.1.7 Burial depth of underwater optical（electrical）cables
Note:The upslope angle of cables on coasts and beaches shall be less than 30°.