mass haul diagram by manesh84

VIEWS: 8,224 PAGES: 5

More Info
									                                                                 Earthwork
                                              • Which involves reduced levels, excavation
                                                of soil, hauled and removal from site.
                Earthwork                     • Important operation in C.Eng.:
                                                – Safety of structure
                                                – Safety of workplace
                                              • Need to be well planned and better in
                                                implementation stage.




        General Consideration &
                                                         Site Consideration
         Planning of Earthwork
1.   Site consideration.                      • Nature and extent of excavation
2.   Ground conditions.                       • Available work area
                                              • Disposal of soil
3.   Contract duration & weather prospects.
                                                – Immediate use as backfilling elsewhere on the site
4.   Economic aspects of earthwork design.      – Storage in spoil heaps, for use later or removal at a
                                                  later stage
                                                – Immediate removal from site to tip or other destination
                                              • Existing services and structures




                                                   Contract duration & weather
          Ground Conditions
                                                            prospects
• Ground support during excavation            • Earthwork are subject to two forms of change
                                                due to weather.
• Best method of keeping the excavation
                                                – 1st: superficial change due to immediate weather
  free from water                                 conditions, e.g. heavy raining.
• Type of plant to be used                      – 2nd: a change due to seasonal conditions, by which
                                                  soils may be affected for a longer period of time.
                                              • Compaction of soil
                                                – Is affected by changes in moisture content and wet
                                                  conditions may render satisfactory compaction
                                                  impossible.




                                                                                                            1
     Economic aspects of earthwork
                                                           The selection of profile
               design
•    The nature of work                            • For the purposed road depends on a
•    The availability of suitable plant              number of factors:
•    The availability of suitable fill material        – Cuts and fills should be minimized as much
                                                         as possible.
•    The time of year
                                                       – Cuts should be balanced as much as possible
                                                         against fills.
                                                       – Distance between successive vertical curves
                                                         should be long




       Mass Haul Diagram (MHD)                     Level
                                                                Soil Profile


• To determine the economically method to                                             Profile Grade
  haul/move/transfer the soil.
• MHD shall determine:
                                                                                                       Stn.
     – Distance/Area: cut=fill
     – Quantity and soil movement direction
     – Soil volume to disposal/import
     – The effectiveness usage of plant           Volume




                                                                                Cross Section




                    Definition                                                 Haul
1.    Haul (Punggah)                               • Volume of earthwork x haul distance
2.    Station yards                                • Unit: station yards/station meters
3.    Free haul (Punggah percuma)                  • M3*station/yd3*mile
4.    Overhaul (Punggah lebih)
5.    Waste
6.    Borrow
7.    Limit of economical haul




                                                                                                              2
              Station yards                                       FH & OH
1 stn.m = 1m3 material transported within 100m   • Contractor fixed charges in hauling the soil
                                                   for certain stated distance, e.g. 150m. If
Example: 20m3 material transported for 1500m       hauled soils exceeding 150m, addition
                                                   charges will be 50 cent for every 100m
                                                   (one station) are
Haul = 20 x 1500/100
                                                 • Free haul:
                                                   – 150m distance
     = 300 stn.m                                   – Determine by plant economical haul distance,
                                                     value: 100m (bulldozer)……3000m (self
                                                     propelled scraper).




                   Waste                                           Borrow
• Cut materials which is not being used for      • Material that is obtained from outside site
  backfilling.                                     area.




      Limit of economical haul                           Swelling & Shrinkage
Example:                                         • Excavated soils will be swelling
Data                                               – Vloose > Vbank/insitu
Free haul distance = 500m
Overhaul = 30cents per stn.m                     • Compacted soils will be shrinking
                                                   – Vcompated < Vinsitu
Borrow = 90cents per m3
Overhaul 1m3 within 300m = 90 cents
  (same with borrowing cost)                     Note
So, LOEH = (300+500) = 800m                        – Normal soil, shrink 10% after compaction
                                                   – Rock will swell 20-30%




                                                                                                    3
                         MHD Criteria                                                  Notes to diagram
x                  Cut                Haul direction        Cross Section

         cg x                                                               • xyz trimmed and leveled to A’B’
                                                  Fill
A’
                                       y                     x cg
                                                                       B’   • Assume backfilling volume after correction
                         Grade line
                                                                              = cutting volume
                                              Grade Point
                                       C                              z




              E                Total haul distance           F



A                                                                      B
                                       D




                           Procedures
1. MHD is cumulative volume curve
     •    The line which is drawn parallel to baseline                      5. Haul direction
          AB shows cutting volume = backfilling                               •   MHD inclining curve on baseline: Haul
          volume                                                                  direction is from left to right.
     •    Parallel line with AB is known as balancing                         •   MHD declining curve on baseline: Haul
          line.                                                                   direction is from right to left.
2. Inclined curve = cutting (+ve)
3. Declined curve = backfilling (-ve)                                       6. Total cut volume will be represented by
4. Maximum point MHD is situated on                                            maximum ordinate (CD).
   grade point.




                                                                                              Solution
7. Soil movement:                                                           Haul = Volume x Distance
     •    Cutting at x will be removed to y
          •       So, initial point for hauling will be situated
                  between x & y (cut centre)
                                                                            Total haul = CD x EF/100 stn.m
          •       Finish point for hauling is situated between y & z
                  (fill centre)
     •    The actual haul points is determined by
          dividing bisecting ordinate for total volume of
          CD with EF line (which is parallel to AB)




                                                                                                                           4
Centre grid

                                                                      1. Assume free haul distance = 100m
                          Balancing Method                                •   Draw a free haul distance on MHD curve
      x               L          Haul direction                           •   Drawing method?
               cg x                                                   2. EF shows:
                                                  N
      A’                                                         B’       •   Cut volume (LMY) = fill volume (YNP)
                          M       y                       x cg
                                                                          •   CC’ volume is in free haul distance area
                                                  P
                                                                 z
                                                                      3. Cut volume XLMA’ is overhaul volume, its
                                  C
                                                                         quantity is represented by EG ordinate.
                                                                      4. XLMA’ volume will be filled into NPZB’.
                                 C’
                      E                               F                  Average distance in between cut and fill centre
                J                                          K             is determined by JK line.

      A                                                          B
                          G       D               H




     5. If JK = 250m                                                  EXAMPLE: Surface level and soil volume tabulation in railway track
                                                                      scheme construction of 1200m.
           •    Free haul = 100m
           •    So, overhaul distance = 250m - 100m =                         Chain            Surface level (m)       Volume (m3)
                150m                                                            70                   52.8
                                                                                71                   57.3                  +1860
     6. Free haul volume                                                        72                   53.4                  +1525
           = CC’ + EG                                                           73                   47.1                  +547
                                                                                74                   44.7                  -238
           = CD                                                                 75                   39.7                  -1080

     7. Overhaul                                                                76                   37.5                  -2025
                                                                                77                   41.5                  -2110
           = overhaul volume x overhaul distance                                78                   49.5                  -1120
                                                                                79                   54.3                  -237
           = EG (JK – EF)
                                                                                80                   60.9                  +362
                                                                                81                   62.1                  +724
                                                                                82                   78.5                  +430




                               Notes                                                                 Q
     • Planning had been implemented without                          1. Plot the cross section for railway track
       taking consideration about aside section.                         profile/scheme.
     • Formation level is located 43.5 on datum                       2. Plot the MHD. Correction factor for
       at 70 chain and normally inclined 1.2%.                           backfill = 0.8. Use 1000m3 scale to
                                                                         20mm.
                                                                      3. Calculate the total haul in stn.m. Show
                                                                         the limit of haul distance on curve and
                                                                         section.




                                                                                                                                           5

								
To top