Deformation behaviour of railway embankment ... - Liikennevirasto

More documents

Recommendations

Info

166 measured for the 600 mm central portion of the specimen's height using three LVDTs placed equally spaced around the circumference of the specimen. Each LVDT measures the relative vertical displacement of the specimen between two "locating anchors" fitted into the body of the specimen after the compaction is completed. It is customary in several other laboratories to use "locating studs" embedded in the sides of the specimen during compaction. Although this arrangement might be suitable for fine aggregates, when the material contains larger particles there is a great risk that the studs are not properly fitted into the material grains, leading to erroneous readings. To avoid this risk, a new method has been successfully implemented for attaching the vertical transducers to the specimen. For this purpose, the compaction mold is provided with three sets of holes, each comprising two 85 mm holes at 600 mm vertical distance. When the specimen is compacted, small holes (8 mm in diameter and 60 mm deep) are drilled into the specimen through the compaction mold and the first membrane. Initial trials have shown that it is necessary to drill the holes before the mold is dismantled, otherwise drilling will disturb the grain arrangement in the area around the holes. After the compaction mold is removed and before placing the second membrane, special aluminium discs are screwed into the holes using standard expandable roller plugs. When the outer membrane is placed in position, threaded rods are screwed into the discs and sealed from the outside using "O"-rings and washers. The LVDTs are then mounted vertically between the rods. The transducer body is attached to the lower rod by the LVDT holder, whereas the core of the transducer is located on an extension rod attached to the upper rod by a bracket. The output voltage of each LVDT indicates the relative movement of the specimen between the two anchors. An enlarged cross-sectional view of the anchoring arrangement used is illustrated in Figure 8.7.2:4. Figure 8.7.2:4 Details of the anchoring arrangement for the axial transducers (Lekarp 1999).
167 The lateral strain is measured by a "string of wheels" mounted half-way up around the circumference of the specimen, as schematically illustrated in Figure 8.7.2:5. Figure 8.7.2:5 Schematic illustration of the “string of wheels” (Lekarp 1999). A steel cable of 2 mm diameter is threaded through 15 sets of wheels and attached at each end to an LVDT holder. Each set of wheels comprises a pair of hard plastic wheels fitted on an axle through which the steel cable is threaded. The axles are equally spaced and locked in position by coating the steel cable between adjacent axles with a plastic cover thicker than the hole through the axles. The string of wheels is then wrapped around the specimen and held together by two springs. It is believed that the system adopted here, with several contact points around the circumference of the specimen, gives a very reliable average measurement of the lateral strain. This technique is, therefore, assumed to be superior to other methods used elsewhere, in which the horizontal displacement is measured at two opposite points. Data acquisition and control system The axial load, confining stress, and displacement transducers all produce electrical output signals that are conditioned and stored by the data acquisition system. As all the measurements are taken inside the triaxial cell, the signals are led through the cell top platen, using sealed outlets. In order to minimise the possibility of electrical disturbance, it was found necessary to provide one outlet to lead the LVDT cables and one for each of the two strain gauge transducers, i.e. the load cell and the pressure sensor. The analogue signals are conditioned and converted to digital electrical signals by the data acquisition and control system (MTS TestStarII ver. 4.0). The resolution of the data acquisition system provides a sensitivity of about 3 µm and 75 N for the LVDTs and the load cell, respectively. The test set is programmed in the computer software provided (MTS TestwareSX ver. 4.0). The experimental measurements can be
Page 1:
A 5/2006 Deformation behaviour of r
Page 4 and 5:
Finnish Rail Administration Publica
Page 6 and 7:
4 Past investigations have shown cl
Page 8 and 9:
6 Brecciaroli, Fabrizio - Kolisoja,
Page 10 and 11:
8 kuvataan jakamalla jännitykset j
Page 12 and 13:
10 TABLE OF CONTENTS ABSTRACT .....
Page 14 and 15:
12 8.9 Trondheim NTNU/SINTEF’s re
Page 16 and 17:
14 combination of resilient strains
Page 18 and 19:
16 Modelling is an important necess
Page 20 and 21:
18 Figure 2.1:2 Two-dimensional sta
Page 22 and 23:
20 σ xx − σ 3 2 det τ yx σ yy
Page 24 and 25:
22 stresses. As it can be seen from
Page 26 and 27:
24 grains. The resistance to partic
Page 28 and 29:
26 The reason was argued to be that
Page 30 and 31:
28 term matric suction implies the
Page 32 and 33:
30 Figure 3.2.1:1 Idealisation of t
Page 34 and 35:
32 ε ε 2 ν = , (Eq. 3.2.2:4) whe
Page 36 and 37:
34 where sij = σ −σ , (Eq. 3.2.
Page 38 and 39:
36 addition, when both the complexi
Page 40 and 41:
38 supplement continuum mechanics m
Page 42 and 43:
40 Figure 4.2:1 A typical variation
Page 44 and 45:
42 Figure 4.2:3 Modulus of resilien
Page 46 and 47:
44 provided that the applied stress
Page 48 and 49:
46 material (Uzan 1985). Dilation i
Page 50 and 51:
48 Figure 4.5:1 Resilient modulus o
Page 52 and 53:
50 The grain size distribution of g
Page 54 and 55:
52 The grain sizes that determine t
Page 56 and 57:
54 4.6.3 Fines content A simple cha
Page 58 and 59:
56 grained than for fine-grained ag
Page 60 and 61:
58 and the shape of the particles a
Page 62 and 63:
60 Figure 4.7:1 Effect of the wetti
Page 64 and 65:
62 Figure 4.7:3 Modulus of resilien
Page 66 and 67:
64 Figure 4.7:6 Dry -density as a f
Page 68 and 69:
66 Figure 4.7:7 Resilient response
Page 70 and 71:
68 The form index can be measured u
Page 72 and 73:
70 Hovinmoen are gravel materials.
Page 74 and 75:
72 5 MODELLING OF RESILIENT DEFORMA
Page 76 and 77:
74 5.2.2 Resilient modulus as a fun
Page 78 and 79:
76 M r k2 k3 ⎛ θ ⎞ ⎛ q ⎞ =
Page 80 and 81:
78 the model showed good representa
Page 82 and 83:
80 discussed. However it can be exp
Page 84 and 85:
82 et al. (2003) calculated the res
Page 86 and 87:
84 p u = unit pressure (1 kPa), δp
Page 88 and 89:
86 Figure 5.2.5:2 Vertical resilien
Page 90 and 91:
88 2 1 ⎛ ⎞ = A q ε ν p ⎜1
Page 92 and 93:
90 Figure 5.3:2 An example of the c
Page 94 and 95:
92 by incorporating a coefficient o
Page 96 and 97:
94 6 FACTORS AFFECTING PERMANENT DE
Page 98 and 99:
96 cycles. He drew the general conc
Page 100 and 101:
98 accumulated strain, ε p , is co
Page 102 and 103:
100 Figure 6.3:1 Effect of loading
Page 104 and 105:
102 load” is not equal to the fai
Page 106 and 107:
104 Chan (1990) noticed, in his stu
Page 108 and 109:
106 Youd (1972) studied the behavio
Page 110 and 111:
108 Figure 6.5:2 Comparison of plas
Page 112 and 113:
110 ample fine-grained fractions th
Page 114 and 115:
112 of a dolomitic limestone with a
Page 116 and 117:
114 Fuller curve (Equation 4.6.2:3)
Page 118 and 119: 116 Figure 6.6:7 Elastic and plasti
Page 120 and 121: 118 Figure 6.7:1 Dependence of the
Page 122 and 123: 120 0,7 0,6 Elastic limit Failure s
Page 124 and 125: 122 Figure 6.8.1:1 Influence of fin
Page 126 and 127: 124 explain why the differences in
Page 128 and 129: 126 was then argued that the variat
Page 130 and 131: 128 7 MODELLING OF PERMANENT DEFORM
Page 132 and 133: 130 Figure 7.2:1 Mohr-Coulomb repre
Page 134 and 135: 132 where K p (N) = bulk modulus wi
Page 136 and 137: 134 1993)) have reported that at le
Page 138 and 139: 136 ε 1,p = accumulated permanent
Page 140 and 141: 138 Barksdale (1972) conducted repe
Page 142 and 143: 140 Figure 7.6:2 Relationship betwe
Page 144 and 145: 142 also be employed for pavement d
Page 146 and 147: 144 repeated loads, although adapta
Page 148 and 149: 146 series of specimens (or in a mu
Page 150 and 151: 148 Figure 7.7:5 S-N design models
Page 152 and 153: 150 In conclusion, both Huurman (19
Page 154 and 155: 152 aim to simulate as closely as p
Page 156 and 157: 154 by the American Association of
Page 158 and 159: 156 Confining pressure is applied t
Page 160 and 161: 158 particles. During the test, the
Page 162 and 163: 160 method takes the average value
Page 164 and 165: 162 Figure 8.7.2:2 Schematic illust
Page 166 and 167: 164 through each platen is provided
Page 170 and 171: 168 displayed on the monitor in gra
Page 172 and 173: 170 unbound granular materials. The
Page 174 and 175: 172 Figure 8.8.2:2 Permanent axial
Page 176 and 177: 174 performance-related (functional
Page 178 and 179: 176 the six supports of the vertica
Page 180 and 181: 178 under the same isotropic stress
Page 182 and 183: 180 9 CONCLUSIONS 9.1 Resilient def
Page 184 and 185: 182 − Permanent deformation resis
Page 186 and 187: 184 Balay J., Gomes Correia A., Jou
Page 188 and 189: 186 Cheung, L.W. (1994). Laboratory
Page 190 and 191: 188 El abd, A., Hornych, P., Breyss
Page 192 and 193: 190 Hoff, I., Nordal, S., and Norda
Page 194 and 195: 192 Kolisoja, P. (1996b) Large Scal
Page 196 and 197: 194 Mitry, F.G. (1964). Determinati
Page 198 and 199: 196 Plaistow, N.C. (1994). Non-Line
Page 200 and 201: 198 Tam, W.A. and Brown, S.F. (1988
Page 202 and 203: 200 Wellner, F. (1996). Influence o
Page 204 and 205: Liite RHK:n julkaisuun A 5/2006 1 L
Page 206 and 207: Liite RHK:n julkaisuun A 5/2006 3 2
Page 208 and 209: Liite RHK:n julkaisuun A 5/2006 5 R
Page 214 and 215: RATAHALLINTOKESKUKSEN JULKAISUJA A-
show all

Deformation behaviour of railway embankment ... - Liikennevirasto

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?