8 7 011 7 Journal of Highway and Transportation Research and Development Vol. 8 No. 7 Jul. 011 100-068 011 07-0014 - 05 1 1. 0009. 710064 k 0 Merchant 4 Merchant U416. 1 + 6 A Stress Relaxation Test and Constitutive Equation of Saturated Soft Soil YAO Beibei 1 MA Haohao 1. School of Civil Engineering Tongji University Shanghai 0009 China. School of Highway Chang'an Univwesity Xi'an Shaanxi 710064 China Abstract The stress relaxation test of the saturated soft soil was performed by using k 0 continuous loading consolidation apparatus the axial stress and relaxation rate of saturated soft soil changing with time in the relaxation phase were analysed. Based on the Merchant model the nonlinear model for description of stress relaxation properties of saturated soft soil was established by using variation of parameter and comparative analysis of the model calculated and test data was performed. The results show that 1 The relaxation stage of saturated soft clay includes relaxation acceleration stage and relaxation deceleration stage. With the time increasing the stress decreases and gradually stabilizes in the relaxation phase which producing certain residual deformation. The relationship between stress level and relaxation stress is linear the established variable parametric nonlinear model contains four parameters which related to the nature properties of soil those parameters can be obtained by back computation based on 1D relaxation test 3 the model reckoning fits well with the test data indicating that it provides a strong basis for the study of properties of soft soil relaxation. Key words road engineering saturated soft soil Merchant model stress relaxation relaxation stress 0 1 010-1 - 06 1983 -. yaobei31@ 16. com
7 15-4 k 0 Merchant 1 1 1. 1 k 0 h 0. 01 mm k 0 1. 3 w p 31 w L 59 I p 8 1. 3 S r 99% ρ 1. 69 g /cm 3 e 0 1. 44 1. 4 100 00 300 400 kpa Fig. 1 Relation between axial stress and time 1. 1 3 1 1
16 8 3 D i 5 E. Δσ i 1 4 E 3 4 Maxwell Fig. 4 Relation between relaxation stress and stress level Burger Merchant 4 5-6 Maxwell Merchant Δσ i Eσ i + F 1 7-8 E 0 E F E 1 K 1. 3 t i /σ vi t t i 3. 1 1 Merchant K 5 1 ε + E 1 ε E 0 + E 1 σ + K 1 σ 3 E 0 E 0 5 t i /σ vi t t i 3 ε 0 ε ε t i σ vi t C 3 it - D i E 0 + E 1 σ + K 1 σ E i t i σ vi t E 0 E 1 ε 4 0 E Fig. 5 5 t i /σ vi t - t i Relation between t i /σ vi t and t i E E ε 1 4 E 1i E σ vi t + K i σ vi t [ - σ vi ] t E σ vi t - σ vi t t [ ] t E 1-1 C i t ε - 1 5
7 17 { } K i E 1i - σ vi t - E σ vi t σ vi t [ ] t 0 - E σ vi t D i E D iσ σ vi t t 0 ε 6 σ vi t D i 5 6 4 σ vi t + D i - 1 σ 1 vi t D i ( - 1 7 ) 7 σ vi t 1 + A i e - D i σ -1 t 8 t 0 σ vi t e - D i σ - 1 t 1 8 A i - 1 9 9 8 ( ) i 10 D i 4 D i t 0 t D i 6 Qε P 11 D i Mε N 1 Q P M N 11 1 10 ( ) σ vi t ε -P Q + - ε -P Q Qε P -N e - M Qε p -1 13 13 4 M N Q P 13 t σ t 0 σ t 0 6 Fig. 6 3. 3 D i Relation of and D i with strain level σ vi t 1 + σ C - 1 e - D i σoi i C -1 t 10 13 10 Merchant 7 ~ 9 3.
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