matric suction, what is it - root barrierrootbarrier.com.au/education/matric_suction_flyer...
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Matric suction is the pressure dry soil exerts on the surrounding soils to equalise the moisture content in theoverall block of soil.
Matric suction conditions in the soil profile were obtainedthrough steady state unsaturated seepage analyses. The initial matric suction profile is the same as suction variedfrom 409 kPa at tree root to 49 kPa at lower boundary of thesoil domain. The contours of changes in matric suction arepresented in Fig. 11. The closer to the tree, the more changein suction is observed. The results of stress-deformationanalysis are shown in Fig 14 as contours of vertical displacement. A maximum foundation settlement of 80mmand minimum settlement of 25 mm was observed. A maxi-mum settlement in the soil profile took place at tree locationand decrease with horizontal distance and depth.
TM
Includes Extracts of Proceedings of Geo-institute Shallow Foundations and Soil Properties Committee sessions at the ASCE 2001 Civil Engineering Conference. (2001). Expansive Clay Soils and VegetativeInfluence on Shallow Foundations (pp. 36 - 37). Houston: American Society of Civil Engineers.
Figure 10. Illustration of Example 2
Figure 11. Contours of Final Matric Suction (kPa) Figure 14. Contours of vertical displacements (mm)
200250
150
150
100 kPa
Root uptake 0.5 m3/day
Ground-water table – 15 m
Distance from trees (m)
Dept
h(m
)
e0 = 1.0Cm = 0.2µ = 0.3ks = 5 mm/day
300
350
400
0 4 8 12 16 20
02468
10
-20 mm-40-80 -60
-100-120
Distance from trees (m)
Dept
h(m
)
0
0 4 8 12 16 20
02468
10
200250
150
150
100 kPa
Root uptake 0.5 m3/day
Ground-water table – 15 m
Distance from trees (m)
Dept
h(m
)
e0 = 1.0Cm = 0.2µ = 0.3ks = 5 mm/day
300
350
400
0 4 8 12 16 20
02468
10
-20 mm-40-80 -60
-100-120
Distance from trees (m)
Dept
h(m
)
0
0 4 8 12 16 20
02468
10
200250
150
150
100 kPa
Root uptake 0.5 m3/day
Ground-water table – 15 m
Distance from trees (m)
Dept
h(m
)
e0 = 1.0Cm = 0.2µ = 0.3ks = 5 mm/day
300
350
400
0 4 8 12 16 20
02468
10
-20 mm-40-80 -60
-100-120
Distance from trees (m)
Dept
h(m
)
0
0 4 8 12 16 20
02468
10
M AT R I C S U C T I O N , W H AT I S I T ?
H OW D O WE MI N I M I S E T HES HR I N K AG E O F R E ACT IV E C L AY ?
By placing a 1.5 to 2 metre root proof andwaterproof wall around the structure that wewish to protect. This will create a island effectand keep the change in moisture content to aminimum. Root barrier will effectively disconnectthe tree from the moisture under the slab.
ROOT BARRIER is a flexible waterproof cutoff wall which will achieve both goals ofstabilising the clay an keeping the tree rootsaway.
Root Barrier is locally produced to suit Australian conditions, stock is on hand and available.
Good service, good prices, sound advice and a happy disposition make work an enjoyable place to be.
ROOT BARRIER help line 1300 136 644 (Australia Only) International Tel +61 7 3861 0141Download design typicals at www.rootbarrier.com.au
MATRIC SUCTION FLYER 17/12/07 2:33 PM Page 1