Green Active Net Anchorage And Sprayed Ecological Concrete Protection Technology For Fragmented Rock Slope And Its Application

Due to the effects of rainfall and earthquake,the shallow surface of the mountain highway slope suffers from erosion and weathering.With the development of a large number of engineering construction,the slope rockfall,the collapse of dangerous rocks and the local slide collapse disasters are easy to occur,which pose a great safety hidden danger to pedestrians and drivers on the road.The reinforcement of the broken rock slope includes the reinforcement of the whole slope and the shallow surface.The paper analyzes the characteristics of the shallow surface disaster of the broken rock slope and gives the disaster prevention suggestions.Based on the analysis of common calculation methods of anchoring slope,the design calculation method of green active net anchoring and shotcrete ecological concrete to protect the anchoring slope is proposed,and the calculation formula of the optimal Angle of the anchoring slope is deduced.Based on numerical simulation and field tests,the reliability of green active net anchorage and shotcrete ecological concrete protection technology for the overall slope and shallow surface reinforcement of fractured rock slope was tested.Based on the ecological protection engineering of the slope of the supporting project,the construction process and key construction technologies of green active net anchorage and shotcrete ecological concrete protection technology for the broken rock slope are studied.The evaluation system of slope ecological restoration is put forward to comprehensively evaluate the effect of slope ecological restoration.The main work and conclusions are as follows:(1)The green active net anchorage and sprayed ecological concrete protection technology can improve the overall stability of the whole and the shallow surface of slope,and at the same time restore the slope ecology.The main reinforcement mechanism is to increase the overall stability of the slope through the anchor rod,increase the stability of the shallow surface of the slope through the metal mesh and ecological concrete,and plant roots can also play a role in reinforcing the soil in the later stage.During rainfall,vegetation can intercept rainfall and release splash erosion,reduce pore water pressure of rock and soil mass in the shallow surface layer of slope,and restrain slope runoff,which further improves the stability of the shallow surface layer of slope.After the vegetation grows,it can completely shield the protective measures and constitute an ecological protection system for the slope(2)When the strength reduction method is used to analyze the slope stability,there is no obvious sliding surface in the calculated results.The maximum shear strain element values in the grid in the sliding surface area of the slope can be extracted and connected into arcs to form the most dangerous sliding surface of the slope.(3)For the calculation of the optimal bolt inclination Angle of rock slope with circular sliding surface,the distribution of initial sliding surface should be considered.The bolt inclination Angle should be:??90°-?_i.Considering the construction quality assurance of the bolt and the effective anti-sliding component force of the bolt,the Angle of the bolt should also be guaranteed to be:10°???60°.In the preliminary design calculation,the tilt Angle of the bolt should be 45°.When the Angle of the bolt is over 50°,the slope safety factor decreases more rapidly,and the calculated slope safety factor decreases by more than20% compared with the maximum value.The greater the thickness of the soft rock,the higher the ratio of the safety factor decreases.Therefore,for the slope with thick soft rock strata,the design Angle of anchor bolt should not be greater than 50°.(4)Due to its high moisture content and internal binder not yet playing a role,the shear strength of ecological concrete is low after spraying.Therefore,attention should be paid to avoid rainy days during spraying construction of ecological concrete.The binder mainly affects the cohesion index of the substrate,and the improvement effect of plant roots on the cohesion index of the substrate is more obvious than the internal friction Angle.After spraying for 14 days,its shear strength is high,and it has a good protective effect on the shallow surface of the slope.The local stability of the shallow surface of the slope is good,which verifies the reliability of the green active net anchorage and shotcrete ecological concrete protection on the shallow surface of the slope.(5)Four indexes of safety,durability,economy and ecological restoration effect should be examined in the selection of protection schemes for broken rock slope.For slope protection engineering,safety is the most important index.Durability,economy and ecological restoration effect of slope influence each other,and the evaluation should be a parallel relationship.Among the three slope protection schemes,the maximum protection weight of green active net bolt-shotcrete is 0.5222,and the minimum weight of bolt frame beam is 0.1755.The green active net bolt-shotcrete protection technology should be the preferred reinforcement scheme of fractured rock slope.(6)The evaluation of the ecological restoration effect of the broken rock slope should examine the quality of ecological concrete,the quality of plants,the quality of slope landscape and the economic benefits brought by the ecological restoration of the slope,among which the quality of ecological concrete largely determines the achievement effect of the other three indexes.The nutrient content of ecological concrete determines the growth condition of slope plants.The plant quality was affected by the ratio of ecological concrete seeds and the nutrient content of ecological concrete,which had high controllability and was a weak influence index.The vegetation landscape of slope is determined by the growth of slope plants,and the effect of slope ecological restoration is relatively weak compared with the other three indexes.Fuzzy comprehensive evaluation method is used to evaluate the ecological restoration effect of the slope,and the result shows that the ecological restoration effect is "good".