Due to high reactivity and relatively low cost, nano zero-valent iron (nZVI) has become an alternative material for in-situ remediation of contaminated sites. However, factors such as short transport distance and easy deposition in porous media also seriously restrict its injection remediation effect. The optimum ratio of bentonite and kaolin supported nano zero-valent iron (K-nZVI) in the remediation agent was determined by sedimentation and rheological tests. The transport characteristics of deionized water and bentonite suspensions carrying K-nZVI in porous media under different injection pressures were investigated using simulating column tests. The results show that bentonite suspensions could significantly improve the stability and dispersibility of K-nZVI. The proportion of bentonite and K-nZVI are 5% and 0.4%, respectively, which is the best ratio of the remediation agent. The transport capability of K-nZVI carried by deionized water increases with the increase of injection pressure, while there is a critical injection pressure for bentonite suspensions carrying K-nZVI remediation agent. The numerical simulation results show that the diffusion radius of K-nZVI is positively correlated with the injection pressure and negatively correlated with the viscosity of the remediation agent. The results provide theoretical guidance for the remediation project of heavy metal pollution in non-ferrous smelting sites.

In the process of split grouting, soil will compress the surrounding soil under the action of expansion pressure, reduce the gap between soil particles. Based on this, the stress-strain relationship model describing the nonlinear compression characteristics of soil mass was established to simplify the dynamic development process of split grouting veins. Considering the loss of grouting pressure along the path, the corresponding relationship between the set value of the first sequence grouting circle cake pulse diffusion radius rmax1 and the set value of grouting pressure p0 was obtained, and the corresponding calculation method of grouting time was obtained. Under the condition that the previous sequence grouting changes the distribution direction of the major and minor ground stress, the corresponding relation between the secondary grouting diffusion radius rmax 2 and the set value of grouting pressure p ' 0 and the calculation method of grouting time are obtained. The model test of split grouting is carried out, and the test results show that the vertical split grouting can be achieved by setting the target pressure and grouting time after the horizontal split grouting and the direction of the ground stress change, which verifies the rationality of the theory.