| The modified hydrophilic polyurethane(plant consolidation material,referred to as W-OH),which is developed to control the slope instability and soil erosion in Pisha sandstone area in China,has a good effect of anti-corrosion and promoting growth.After the mixture of W-OH and water,the composite solution can form a consolidation layer on the surface of Pisha sandstone,and the good performance of the consolidation layer is the basic prerequisite for W-OH to control slope instability in Pisha sandstone area.At the same time,the interface between the plant consolidation layer and the original soft rock is formed on the Pisha sandstone slope,and the physical and mechanical difference between the interface makes the interface strength become the key to this kind of slope protection.At the same time,due to the special climate of the Pisha sandstone area,the geotechnical engineering in this area is inevitably affected by the deterioration of the interface caused by the cycle of dry and wet and freeze-thaw.Therefore,relying on the national key research and development project-"Pisha sandstone Ecological Security guarantee Technology(2017YFC0504505)",this paper mainly studies the shear characteristics between plant consolidation and original Pisha sandstone under the influence of climate factors such as dryness,humidity and freeze-thaw when W-OH is used to control the exposed Pisha sandstone slope with serious weathering in soft rock area,which provides technical support and scientific basis for W-OH material to effectively consolidate the stable slope of Pisha sandstone.The main contents of this paper are as follows:(1)Under the condition of dry-wet cycle,combined with direct shear test,the effects of different W-OH concentration and different moisture content on interfacial shear strength were studied,and then the law of interfacial damage caused by dry-wet cycle was explored under the optimal conditions of 10%W-OH concentration and 8%moisture content at the interface.The test results show that the shear strength of the interface has a positive correlation with the concentration of W-OH and a negative correlation with the moisture content at the interface,and the cohesion between the interface decreases at first and then tends to be stable with the increase of the number of dry-wet cycles.Combined with the observation and analysis of ultra-depth-of-field microscope,it is found that the damage to the interface caused by dry-wet cycle mainly includes the shedding of W-OH cement,cracking and the increase of pores between Pisha sandstone particles.(2)Under the condition of freeze-thaw cycle,the damage law of freeze-thaw cycle under different W-OH concentration and moisture content was studied based on direct shear test.The results show that the interface of the sample prepared by high concentration W-OH solution has good freeze-thaw resistance.However,with the increase of freeze-thaw cycles and water content at the interface,the interfacial shear strength between plant consolidation and Pisha sandstone decreases.Also combined with the microscopic analysis of the failure surface,it is found that the repeated shrinkage-expansion under the freeze-thaw cycle causes the plant consolidation at the interface to fall off and gradually produce cracks,which reduces the bonding performance of the material.(3)Based on the above damage mechanism,ethylene-vinyl acetate(EVA)was used to modify plant consolidation materials to improve the durability under dry-wet and freeze-thaw cycles.The results show that the addition of EVA can not only increase the adhesion of W-OH materials,but also further fill the pores between soft rock particles at the interface,and effectively improve the dry-wet,freeze-thaw durability of the interface between plant consolidation and Pisha sandstone. |
PDF Full Text Request