| The slope collapse of granitic residual soil exists in the southern part of China.The granitic residual soil retains in original structural features that influence or even control the infiltration model of the soil.The infiltration differences generated by different fracture characteristics increase the difficulty of determining the stability of granitic residual soil slopes.In this paper,a numerical model of slope infiltration under the difference in fracture characteristics will be developed based on physical modeling experiments with dense sandy soils of granitic residual soil.In addition,the sensitivity of fracture characteristics to infiltration processes will be obtained,with particular attention to the infiltration model of dominant infiltration under the difference in fracture characteristics.Finally,the stability of the slope under the difference of infiltration patterns will be further evaluated quantitatively.The fine-scale results of the numerical simulations can be combined with the macroscopic findings of the existing tests to clarify the process of fracture-dominated seepage.The main work carried out and the results obtained are as follows:(1)Based on the physical model test data,a discrete element numerical model of the inter-particle moisture transfer rule was established.The slope wetting front characteristics and complete infiltration duration of the experimental test were analyzed,so as to calibrate the water transfer rule of slope infiltration to establish the discrete element numerical model.Finally,the reliability of the numerical model was verified.The results show that the fracture attitude determines the rule of infiltration in the numerical simulation.With fracture attitude#2(0°)as the axis of symmetry,the fractures with symmetrical dip angle have consistent water resistance and conductivity.The moisture transfer rate is faster in the initial and saturated water content regions,and the moisture transfer rate is the same in other water content regions.The moisture transfer rate increases with the infiltration time.(2)The infiltration fine-scale evolution process of fractured granitic residual soil slopes in the physical model is inverted by numerical simulation.The change patterns of wetting front,water content,infiltration coefficient and complete infiltration duration of slopes under the influence of fracture morphology combination were calculated and analyzed by using discrete element numerical model.As a result,the spatial and temporal characteristics of the occurrence of fractured air-resistor and infiltration are obtained.In the initial stage of infiltration of time T/4,the infiltration of the shallow surface layer of the slope under each combination of fracture spatial attitudes shows a blocking effect.The fractures in the whole infiltration process show the blocking effect orthogonal to the infiltration direction,and the blocking and infiltration effects exist simultaneously in the same direction of infiltration.In the time duration 4T/5,the infiltration is controlled by the orthogonal fractures when the infiltration does not reach the intersection of the combined fractures,and vice versa,the orthogonal fractures dominate the infiltration.(3)The infiltration patterns of fractured granitic residual soil slopes and their stability difference characteristics are established for the migration characteristics of wetting fronts under fracture combination and attitudes.The calculation equation of wetting front depth of slope under the combination of fracture pattern is optimized.The wetting front finger-in characteristics of slope are quantified and characterized.The infiltration pattern of slope under the mutual variation of fracture and bedrock production is clarified,and the stability difference and sliding characteristics of fractured slope characteristic moments are obtained.The results of the study showed that: the infiltration of fracture-influenced granitic residual soil slopes is in accordance with the Kostiakov model.The infiltration process has obvious fingering characteristics.The fracture attitude for the dip angle of 77° and 56° are the maximum and minimum values of the fingering effect,respectively.And the fastest finger advance at 34° fracture dip.The maximum difference of slope stability under the influence of fractures can reach 14%.The stability coefficient of the most sensitive fracture attitude(horizontal)lower slopes is 13% greater than that of fracture-free slopes. |
