隐伏逆冲断层上填方路基加固措施与变形破坏模式探究

Reinforcement measures and deformation failure modes of subgrade on embedded reverse fault

试验路基以云贵铁路某填方路基为原型，试验路堤底部宽L=60cm，路堤项部宽l=10cm，路堤高h=15cm，采用室内模型试验研究了4组减震措施在逆冲断层作用下填方路基的变形响应。第1组是把路堤直接坐落在地基上，这组试验也是一组基本试验，其他试验组的试验结果可与该组试验结果进行对比；第2组是在路堤底部铺设一层土工格栅；第3组是在路堤中部和底部各铺设一层土工格栅；第4组是在路堤底部黏土层中打入预制的CFG桩，同时在路堤底部和中部各铺设一层土工格栅。试验中利用分离式位移计和百分表记录路堤的变形数据，通过对数据的处理分析研究路堤在不同加固措施下的变形破坏模式，研究结果表明：（1）在4组模型中，路基破坏主要是路堤本身产生了斜45°的裂缝；（2）在底部基岩错动量小于路堤高度13．6％时，路堤中加入两层土工格栅达到的减震效果最佳；当基岩错动量在路堤高度13．6％-20．5％之间时，CFG桩与路堤中加入两层土工格栅的减震措施最有效；（3）随着减震措施的加强，断层位移在地层中传播的角度变缓，影响范围加长，产生的震害程度降低了。研究结果对工程实践具有重要的指导意义。

The experimental subgrade is used to model a high embankment in the Yunnan-Guizhou Railway, which has a bottom width of L=60 cm, top width of l=10 cm, and height of h=15 cm. The experiment models are used to study the effect of four ground stabilizing measures （called four groups） on responses of the high embankment under the action of a thrust fault ruptures. Group 1 is the case that no ground stabilizing measure is taken and is a basic test. The results from the other three groups are all compared with that from group 1. Group 2 is the case that a layer of geogrid is laid at the bottom of the embankment, Group 3 is that two layers of geogrids are laid at the middle and bottom of the embankment respectively, and Group 4 is that CFG pile is used to stabilize the ground and two layers of geogrids are laid at the bottom and middle of the embankment respectively. Several displacement gauges and dials are used to record embankment deformation. Deformation and failure modes by caused by different stabilization measures are analyzed. Results show that： （1） In the 4 models, embankment damage is mainly caused by the crack of 45° in embankment. （2） When fault displacement is equal to or less than 13.6% of the embankment height, the engineering measure with two layers of geogrids has the best efficiency for reducing damage; when the fault displacement is greater than 13.6% of the embankment height and less than or equal to 20.5% of the embankment height, the measure with both CFG piles and two layers of geogrids can achieve the best efficiency. （3） Due to part of energy absorbed by soil foundation, failure angle in the ground gradually reduces as engineering measure gradually strengthens, as a result embankment damage extent is reduced because the length affected increases. The conclusions in the paper hawe significance for engineering practice.