Highway Slope Manual

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53 Note: (1) The decision to select the ‘sloping berm' option should be made by the designer after careful consideration of the site conditions and other factors (e.g. maintenance, land-take and ease of construction). igure 5.2 erm Channels for a Highway Cut Slope igure 5.3 Examples of Roadside Channels
54 5.2.3 Drainage Improvement Works For existing roads, critical locations should be identified and any road drainage improvement works needed should be carried out in a priority order based on the consequence-to-life and socio-economic consequences should slope failure occur (Figure 5 勾 1) 勾 Where opportunities arise, the necessary improvement works should be carried out as part of a road improvement (e 勾 g 勾 widening or upgrading) project or a new project nearby (see Section 2 勾 2 勾 2), or as part of the slope preventive maintenance programme (see Section 8 勾 3) 勾 Any road drainage improvement works required should be carried out to meet the current standards 勾 The maintenance requirements of the improvement works should be documented in a maintenance manual 勾 The adequacy of the works should be reviewed by reference to the maintenance inspections made, including those on the slopes nearby 勾 Further drainage improvement works should be carried out if found necessary 勾 5.3 WATER-CARRYING SERVICES When designing a new road, opportunity should be taken to locate buried services well away from the crest of slopes 勾 As a general rule, buried services should not be placed in a slope nearer to the crest of the slope than a horizontal distance equal to its vertical height 勾 For road or slope improvement works, the same rule should also be applied to re-route the existing buried services away from the slopes, where practicable 勾 In cases where the siting of new buried services or the relocation of existing buried services outside the crest area is impractical, mitigation measures for minimising the impact of water leakage on slope stability as detailed in the Code of Practice on Inspection & Maintenance of Water Carrying Services Affecting Slopes (Works Branch, 1996) should be adopted 勾 General guidance on trench excavation on or above highway slopes (e 勾 g 勾 for services and utilities) and the precautions to be taken for excavation during the wet season are given in Chapter 9 勾 4 of the Geotechnical Manual for Slopes (GCO, 1984) 勾 Before any trench excavation at or close to the toe of highway slopes is carried out, an assessment should be made of the effects of the proposed works on slope stability 勾 Where necessary, the extent of excavation should be limited and adequate slope supportstabilisation works should be put in place 勾 Special attention should be given to locations where permeable fill is present beneath the road surface (e 勾 g 勾 uncompacted fill bodies and granular sub-base) as such material can convey water over long distances, with the resulting risk of affecting the stability of slopes far away from the location of the leaking buried services 勾
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HIGHWAY SLOPE MANUAL GEOTECHNICAL E
Page 3 and 4: 2 。 The Government of the Hong Ko
Page 5 and 6: 4 STEERING COMMITTEE: Geotechnical
Page 7 and 8: 6 Page No. 3. SITE INVESTIGATION 33
Page 9 and 10: 8 Page No. APPENDICES APPENDIX A -
Page 11 and 12: 10 LIST OF FIGURES Figure No. Page
Page 13 and 14: 12 LIST OF LATES Plate No. Page No.
Page 15 and 16: 14 [BLANK PAGE]
Page 17 and 18: 16 year (Evans et al, 1998), they h
Page 19 and 20: 18 Plate 1.4 Landslide at Ching Che
Page 21 and 22: 20 Plate 1.8 Steep Natural Terrain
Page 25 and 26: 24 Notes: (1) The projects in the P
Page 27 and 28: 26 of the geotechnical hazards and
Page 29 and 30: 28 Table 2.2 Geotechnical Haards Th
Page 31 and 32: 30 for carrying out a GA is given i
Page 35 and 36: 34 Table 3.1 Potential Uses of Diff
Page 37 and 38: 36 or features such as dykes or fra
Page 39 and 40: 38 movement monitoring and control
Page 41 and 42: 40 landslide debris, and the nature
Page 43 and 44: 42 Notes: (1) This Figure is based
Page 45 and 46: 44 Table 4.5 Recommended Minimum Fa
Page 49 and 50: 48 Plate 5.1 Surface Runoff Channel
Page 51 and 52: 50 Cascades, with cover where neces
Page 53: 52 (a) Trash Grill at Inlet of Cros
Page 57 and 58: 56 For the control of visual impact
Page 59 and 60: 58 Plate 6.3 Pattern and Texture Pl
Page 61 and 62: 60 ighways are environments with a
Page 63 and 64: 62 Filling operations for a highway
Page 65 and 66: 64 Blasting is the most common meth
Page 67 and 68: 66 Notes: (1) The responsibility fo
Page 69 and 70: 68 Results of Rockfall Protective B
Page 73 and 74: 72 overseeing the maintenance of th
Page 75 and 76: 74 In addition to the slope upgradi
Page 77 and 78: 76 after each heavy rainstorm event
Page 79 and 80: 78 d n n d d d d d d d
Page 81 and 82: 80 event of a landslide should be b
Page 85 and 86: 84 Federal Highway Administration (
Page 87 and 88: 86 Highways Department (1996). Mana
Page 89 and 90: 88 Wong, H.N., Pang, L.S., Wong, A.
Page 95 and 96: 94 key natural terrain and man-made
Page 97 and 98: 96 and details of all existing slop
Page 101 and 102: -AA (v) relevant services and utili
Page 103 and 104: -A2 (m) (n) 1dentify any statutory
Page 105 and 106:
-A4 Notes: (-) An example of a prog
Page 107 and 108:
106 [BLANK PAGE]
Page 109 and 110:
108 Wong, C.K.L. (1998). The New Pr
Page 111 and 112:
110 of slopes and slope owners and
Page 113 and 114:
112 [BLANK PAGE]
Page 115:
114 (iv)subsidence of ground or roa
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