硅酸钾材料加固土遗址耐风蚀颗粒元模拟分析

西北干旱地区土遗址受风化、风蚀等破坏严重，大量土质文物亟待加固抢修。加固后土遗址的各耐环境因素及加固机制研究是土遗址加固的理论基础。首次引入颗粒元程序PFC，通过改变模型中颗粒间平行连接强度，对硅酸钾（简称PS）加固前后的土样进行数值模拟。在考虑实际土样颗粒粒径和密度的前提下，拟合了生土PS加固前后的抗压和抗拉强度，并将拟合后的颗粒元模型应用于风蚀模拟。通过随机生成挟沙风颗粒，以一定的速度撞向土体，模拟挟沙风的吹蚀作用。挟沙风颗粒数与循环步数成正比例，因此，可以用挟沙风颗粒数来代表吹蚀时间的长短。挟沙风颗粒的速度则代表挟沙风风速。模拟结果表明，在20 m/s的挟沙风吹蚀作用下，风蚀程度随吹蚀时间的增加而增大，未加固土样的风蚀程度增幅度远大于加固土样；同样吹蚀时间条件下，加固土样的抗风蚀强度明显高于未加固土样。这些模拟结论与风洞试验结果的统计规律一致。本研究拟合的颗粒流模型可进一步应用于PS加固机制研究及耐风蚀、雨蚀、冻融等诸环境影响分析研究。

Particle simulation on the effect of potassium silicate reinforcement of ancient earthen site soil to reduce wind erosion

There are many ruins of ancient earthen sites in Northwest China, many of which are destroyed by violent processes of the wind erosion. Reinforcements are needed to protect these cultural heritages. The mechanism of reinforcement and resistance of environmental factors are the fundamental of the reinforcement theory. Particle flow code is used to simulate the soil before and after potassium silicate (PS) reinforcement, which is achieved by changing the parallel bond strength between particles. Compressive and tensile strengths of soil are calibrated with considering the soil particle size and density. The calibrated models are used to simulate the processes of the wind erosion. Sand-driving wind flow is represented by random generating particles with original vertical velocity. Results show that under the erosion of 20 m/s sand-driving wind flow, the magnitude of erosion increases as wind flow duration increases. The increasing magnitude of erosion of soil before reinforcement is much larger than that of reinforcement soil. The resistance erosion capability of reinforcement soil is greater than soil before reinforcement. These conclusions are generally agreed with the indoor wind-tunnel test results. The calibrated particle flow model of this research can be used for further analysis of ancient earthen site soil, such as wind erosion, water erosion, freeze thawing etc.