级配碎石动态力学性能对隧道路面受力的影响

Effects of Dynamic Mechanical Properties of Grading Macadam on Tunnel Pavement Stress

具有良好温湿稳定性的级配碎石常被设置在隧道路面下以排出基岩渗水．文中利用动三轴试验模拟了基岩渗水对级配碎石层动态力学性能的影响，建立了动态回弹模型以表征其力学特性，并采用非线性有限元法分析了路面受力．结果表明：动三轴试验可较好地模拟级配碎石层的实际受力状态；Uzan模型考虑了材料的剪切性能，更能反映级配碎石在隧道路面中的应力状态；随含水量的变化，Uzan模型中回归系数的变化呈明显的非线性特征，进而显著影响级配碎石动态回弹模量的变化；级配碎石模量越大，路面底的最大拉应力变化率越小；为了兼顾级配碎石层的排水渗透功能和改善路面受力状态，应严格控制级配，特别是粒径0．075mm以下的含量宜控制在5％～7％，级配碎石的回弹模量宜控制在200～300MPa之间．

Grading macadam with good temperature and humidity stability is commonly laid under tunnel pavements to drain seepage from the bedrock. In this paper, some dynamic triaxial tests were performed to reveal the effect of bedrock seepage on the dynamic mechanical properties of the grading macadam layer, and a dynamic resilient model was established to describe the mechanical properties of grading macadam. Moreover, the stress state of the pave- ment was analyzed by means of the nonlinear finite element method. The results indicate that （ 1 ） dynamic triaxial tests well simulate the actual stress state of grading macadam under tunnel pavement; （2） the Uzan model conside- ring the shear performance of material better reflects the stress state of grading macadam ; （3） the regression coeffi- cient of the Uzan model presents obvious nonlinearity with the moisture variation, thus greatly affecting the dynamic resilient modulus; （4） the diminishing rate of the maximum tensile stress at the pavement bottom decreases with the increase in macadam modulus; and （5） in order to enhance its draining function and improve pavement stress states, the gradation of macadam should be rigidly controlled-specifically, the content of the macadam in the size of less than 0. 075 mm should be controlled in 5% -7% and the resilient modulus should be in 200 -300 MPa.