水泥土加固法冻胀抑制效应数值模拟

Numerical Simulation on Frost Heave Inhibitory Effect of Cemented Soil

水泥土与人工冻结联合加固法在盾构隧道端头加固中效果明显。本文以南京地铁十号线过江隧道端头联合加固工程为背景,分别进行了水泥土及原状土体冻结温度场和冻胀位移场耦合数值模拟研究,并通过对比实测与数值模拟结果,验证了计算方法的正确性。研究结果表明:冻结管间、冻结管与围护结构间区域降温速度较快,后排冻结管后方受加固体影响,是冻结壁发展最不利部位;冻结管和围护结构的约束作用会抑制周围土体的冻胀,两排冻结管间冻胀位移最大;水泥加固后地层冻胀敏感性明显减弱,地表最大冻胀量为对应原状土的14.3%,1 mm以上冻胀量地层在深度方向上为对应原状土的30.6%。研究结果对进一步探索水泥土与人工冻结联合加固工法有指导作用。

In China,the combination of cement-soil foundation reinforcement with artificial freezing is widely used in the shield tunnel end reinforcement. This paper aims at combining the two methods＇ advantages and creating a new one. In this paper,the coupled numerical simulation study about the freezing temperature field and frost heave displacement field has been carried out; then,the author verify the validity of the calculation method by comparing the calculated and actual values,based on the freezing reinforcement project of the river-across tunnel which is at the eastern end of the Nanjing subway line 10. The results show that： the temperature of area between freezing pipes and area between freezing pipes and envelope structure drops faster,the area behind the back row of freezing pipes is the weak area of freezing wall development; Freezing pipes and envelope structure may inhibite the frost heave of surrounding soil,and the frost heave displacement between two rows of frozen pipes is the largest; Frost heave susceptibility of soil has been weakened significantly after cement reinforcement,the maximum ground frost heaving is14.3% in the corresponding undisturbed soil,1mm or more frost heaving formations corresponding to 30. 6% of undisturbed soil in the depth direction. Results have a guiding role in further exploration of united construction method of cement soil reinforcement with artificial freezing.