Study on Interface Shear Characteristics of Polyurethane-Pisha Sandstone and Pisha Sandstone under Dry-Wet Cycle
At present, the use of hydrophilic polyurethane (W-OH) materials for slope protection in arsenic areas has proved to be a cost-effective slope protection measure, but due to the Polyurethane-Pisha Sandstone and the uncured Pisha sandstone after W-OH solution There are differences in mechanical properties between the two, and the strength of the interface between the two has become the key to slope protection. This article aims to study the shear characteristics of the Polyurethane-Pisha Sandstone and the uncured Pisha sandstone interface under dry-wet cycles and provide a basis for studying the slope stability and dry-wet durability of the Pisha sandstone area improved by the W-OH materials. Based on the direct shear test, firstly, the effects of different W-OH concentrations and water content at the interface on the shear characteristics of the interface are studied, and then the law of dry and wet cycles on the interface damage under the conditions of 10% W-OH concentration and 8% water content at the interface is explored. The test results show that the shear strength of the Polyurethane-Pisha Sandstone and the uncured Pisha sandstone interface is positively correlated with the W-OH concentration and negatively correlated with the water content at the interface. At the same time, it decreases with the increase in the number of dry and wet cycles, and after 9 cycles the strength tends to be stable. Then combined with the observation of the surface morphology of the shear zone of the dry-wet cycle sample with the ultra-depth-of-field microscope, it’s found the dry-wet cycle damage to the interface mainly includes cement shedding, cracking, and the increase of pores between the Pisha particles. Based on the above mechanism, the W-OH material was further modified with ethylene-vinyl acetate (EVA). The test results show that EVA can enhance the dry-wet durability of the obvious interface.