Study On Strengthening Effect Of Mulan On Slope

Due to the complicated terrain and fragile geological problems during the construction of expressways,high-filling and deep excavation will occur,which not only breaks the local ecological environment system,but also easily causes geological disasters such as soil erosion,landslides,and debris flows that threaten the safety of life and property.With the continuous development of road construction in China,more and more attention is paid to the construction of slope engineering,and the study of effective prevention and treatment measures is an important issue to ensure slope.This article relies on the State Forestry Administration’s 948 project"Introduction of Key Techniques for Landscape Restoration of Deep Road Cutting Slopes"(Project No.101-9968)and the physical engineering of the 8th contract section of Dayue Expressway.The main results are as follows:(一)Study on Root Morphological DistributionBy simulating the self-made model box with similar conditions on the slope,it is found that the horizontal root of the 2-year-old Magnolia multiflora in the model box is the most developed and the longest is 50cm,and there are many oblique roots and vertical roots,while the vertical roots are 60cm long The proportion of rooting and vertical roots is approximately equal to the amount of horizontal roots,and the overall root shape is tapered,and the effective roots are mainly distributed in the soil layer in the range of 0-60cm.The root coefficient and cross-sectional area of Magnolia multiflora increase first and then decrease,and there is a peak.After reaching the peak,the root number decreases more with the increase of depth.Finally,according to the analysis of statistical data,The relationship between the root coefficient and the total cross-sectional area and depth can be obtained.(二)Study on mechanical effects of root-soil complexThe tensile strength of Magnolia multiflora root system varies from thin to thick with root diameter ranging from 17.82 to 80.99 MPa.Compared with HPB235 steel bar,the tensile strength is about 3/40 to 1/3 of the steel bar.With the increase of water content,the maximum pullout force of Magnolia multiflora root system increases first and then decreases.When the water content is about 21.5%,the root pullout force reaches the maximum value,and its root system The tensile strength in the diameter range is 17.6～167.6N.When the water content is 21.5%,under the same normal stress,the shear strength of the composite increases first and then decreases with the increase of root content.It can be obtained that the critical root content is about 0.6g/cm3.(三)Research on Hydrology and Ecological EffectsWhen rainfall intensity>soil infiltration rate,the smaller the rainfall intensity,the higher the vegetation coverage,the longer the slope runoff time,the less the sediment content carried by the slope runoff caused by rainfall,the coverage is 100%The slope of the slope is only 0.14%and 0.23%,and the slope is relatively stable.Considering the changes of plant transpiration and water absorption on the internal water content of the soil,and based on the theory of hygroscopicity and capillary pressure,the expression of plant suction when the soil particles are loosely packed and closely packed is obtained from a microscopic perspective.Because the plant roots occupy the pores of the soil and affect the infiltration of the wet front,the Green-Ampt model is improved accordingly,and an improved wet front depth formula is obtained,combined with the additional anti-sliding force provided by the tensile properties of the root system to obtain the vegetation slope under rainfall conditions.Formula of safety factor for saturated infiltration.