基于支护结构安全系数的铁路隧道围岩膨胀性分级方法

Grading Method of Dilatability of Railway Tunnel Surrounding Rock Based on Supporting Structure Safety Coefficient

采用室内试验方法建立隧道膨胀性围岩含水量、加载压力与膨胀率的关系,以及自由膨胀率与无荷膨胀率、有荷膨胀率的关系;采用数值方法模拟新建山西中南部铁路线上庄1号隧道的施工过程,计算得到了不同膨胀率条件下各施工步序支护结构各截面的弯矩和轴力,从而计算出安全系数;基于隧道施工过程中支护结构安全系数计算,建立不同线膨胀率与隧道结构安全系数的关系并得到其计算公式,进而根据自由膨胀率、50 kPa荷载下有荷线膨胀率将膨胀土划分为Ⅰ～Ⅳ级。研究成果为类似膨胀土隧道的修建提供参考,具有重要的现实意义。

Through lab experiment, the relationships between water content of tunnel swelling surrounding rock, loading pressure and swelling rate were established, also relationships among free swelling rate, swelling rate without load and swelling rate with load were established. Using numerical method, the construction procedure of Shangzhuang No. 1 tunnel on the Mid-south Railway of Shanxi province was simulate, and the bending moment and axial force of every cross-section of supporting structure of every construction stage with different swelling rates were calculated respectively. Then the safety coefficient was worked out. On the basis of above-mentioned safety coefficient, and after establishing the relationship between different linear swelling rate and tunnel safety coefficient, the calculation formula was obtained. Further, according to free swelling rate and linear swelling rate with the load under 50 kPa, the authors divided the swelling rocks into I - IV levels. The results could serve as a reference to similar swelling rock tunnel and have a significant meaning.