Intelligent Soil Compaction Systems (2010) / Chapter Skim
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Relationship Between Roller-Based stiffness and in situ Response c h a p t e r 4 This chapter explores the relationship between rollermeasured stiffness and in situ stress-strain-modulus behavior. Numerous vertically homogeneous embankments and layered subgrade/subbase/base TBs were instrumented with stress and strain sensors at multiple levels to capture in situ behavior during static and vibratory roller passes.
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4.2 Measurement Depth in Vertically Homogeneous Embankments Roller MVs from typical highway construction earthwork rollers (11 to 15 tons) measure to depths significantly greater than a typical 15- to 30-cm (6- to 12-in)
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Figure 4.3.
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Figure 4.4.
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rule of thumb reported in the literature (e.g., Anderegg and Kaufmann 2004)
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enced by the soil response in the x and y directions. Similarly, a vertical dynamic deformation modulus M can be extracted from the cyclic in situ σ z -ε z response to vibratory loading.
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0 Figure 4.6. Total roller-induced (a)
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Figure 4.7.
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Figure 4.9.
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fluenced by a number of factors including stress-dependent modulus of each material, drum/soil contact width, the stiffness ratios of the involved layers, and roller/soil dynamics. The topic is not fully understood and is an area of ongoing research.
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tures are a function of layer thickness, the relative stiffness of the layers, vibration amplitude or F ev , and other drum/soil interaction factors. This section addresses the instrumented roller's ability to sense stiff layers atop a softer subsurface, i.e., to what degree are roller MVs representative of a relatively thin layer or lift of base or subbase material atop subgrade?
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80 MPa throughout compaction, while E LWD-P3 increases from about 75 MPa after the second pass to 90 MPa after the sixth (and final) pass for the first lift of base material.
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4.5 Conclusions The following conclusions can be drawn from the results presented in this chapter. • Vibratory and static rolling induces a complex threedimensional stress-strain-modulus state in the soil.
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