污染土壤高压旋喷修复药剂迁移透明土试验及数值模拟

高压旋喷技术近几年开始应用于污染土壤修复,对所注入药剂的迁移扩散规律尚不明确,导致工程实践中缺乏可靠依据,同时为克服常规试验测试手段的不足,使用透明土材料开展了污染土修复药剂迁移的室内试验和数值模拟。在考虑分子扩散、机械弥散、对流等耦合情况下,建立了探究药剂在土壤中迁移特性的对流-弥散模型。研究结果表明:透明土试验技术能够直观地显示药剂迁移过程,可以应用于污染土修复药剂迁移特性的研究。在不同土壤压力条件下,存在最佳泥饼高度;相同土壤压力,泥饼高度越高,同一位置处浓度最大值越小;泥饼高度的选取关系到高压旋喷参数的设定,对修复效果及效率有重要影响。药剂的迁移以竖向迁移为主,水平向迁移不明显,因此为保证药剂以较高的浓度迁移至泥饼边缘,应使药剂在泥饼间隙水平方向上分布有较高且均匀的初始浓度。

Experiment and Numerical Simulation of Transparent Soil Migrated by High Pressure Rotary Spray Repairing Medicament in Contaminated Soil

High pressure rotary spray technology has just begun to be applied to the repair of contaminated soil in recent years. The law of migration and diffusion of the injected agent is still unclear, which leads to the lack of reliable basis in engineering practice. At the same time, in order to overcome the shortcomings of conventional test methods, transparent soil materials were used to carry out laboratory tests and numerical simulation of the migration of remediation agents for contaminated soil. Considering the coupling of molecular diffusion, mechanical dispersion and convection, an advection-dispersion model was established to investigate migration characteristics of medicament in soil. The research results show that: the transparent soil test technology can visually show the migration process of the medicament and can be applied to study the migration characteristics of the contaminated soil repair agent. Under different soil pressure conditions, there is an optimal mud cake height. Under the same soil pressure, the higher the mud cake height, the smaller the concentration maximum value at the same position. The selection of the mud cake height is related to the setting of the high pressure rotary spray parameter, and has an important impact on the repair effect and efficiency. The migration of the medicament is mainly vertical migration, and the horizontal migration is not obvious. Therefore, in order to ensure that the medicament migrates to the edge of the mud cake at a higher concentration, the medicament should have a higher and uniform initial concentration in the horizontal direction of the mud cake gap.