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交河故城崖体差异风蚀和次生卸荷裂隙发育部位破坏严重,研究二者对崖体破坏的影响以及在其影响下的破坏模式,对加固崖体和保护交河故城具有重要意义,运用有限元软件ANSYS对崖体在差异风蚀和次生卸荷裂隙作用下进行数值模拟。为验证有限元软件模拟结果的可靠性,采用底面摩擦试验对崖体破坏演变过程进行模拟。ANSYS模拟结果表明,被裂隙切割土体最大位移为487.326 mm,崖体卸荷裂隙根部塑性应变最大,崖体拉裂-倾倒破坏。底面摩擦试验结果表明,经过2.7 h崖体顶部的裂隙张开度约20 mm,土体已经倾倒破坏。土体拉裂-倾倒破坏模式为:被卸荷裂隙切割的粉质黏土层底部临空,在重力作用下拉张卸荷裂隙的根部被切割,土体将发生倾斜变形,可能拉断卸荷裂隙的根部而使土体倾倒失稳。针对差异风蚀和次生卸荷裂隙对崖体破坏的影响,提出崖体加固方案。
The differences between the cliffs and the primary unloading fractures in Jiaohe Old City are serious. It is of great significance to study the influence of the two on the cliffs and the failure modes under the influence of them, The finite element software ANSYS is used to simulate the cliff body under the effect of differential wind erosion and secondary unloading fracture. In order to verify the reliability of the finite element software simulation results, the bottom surface friction test was used to simulate the evolution of the cliff damage. The results of ANSYS simulation show that the maximum displacement of soil cut by the crack is 487.326 mm, the plastic strain at the root of unloading crack of the cliff body is the largest, and the fracture of the cliff body is caused by the collapse-dumping failure. The results of the bottom friction test show that after 2.7 h, the crack opening at the top of the cliff body is about 20 mm and the soil body has been collapsed and collapsed. The mode of soil failure-dumping failure is that the bottom of the silty clay layer cut by the unloading fracture is sky-borne. The root of the tension-unloading fracture under gravity is cut and the soil will be inclined and deformed, which may pull off the unloading fracture The roots of the soil dumping instability. Aiming at the effect of differential wind erosion and secondary unloading cracks on the failure of cliffs, the reinforcement plan of cliffs is proposed.