Evolution Law Of Matrix Suction And Bearing Capacity Of The Foundation Under Central-peaked Type-rain Rainfall Infiltration

My country is a country with obvious rainy season.The suction distribution and size of foundation substrate under different rainfall conditions will change,and different suction distribution and size of substrate will affect the change of foundation bearing capacity.The mid-peak type rain type is a common type of rain in life.Existing methods for studying the suction and foundation bearing performance of the foundation matrix under rainfall infiltration often need to be carried out by numerical simulation or indoor tests,but these methods spend long time and cost high shortcomings,therefore,establishing a set of methods that can quickly and easily reveal the evolution law of foundation matrix suction and the evolution of the ultimate bearing capacity of the foundation under moderate peak rainfall infiltration,which is conducive to evaluating the bearing capacity of the foundation under rain infiltration during the rainy season to facilitate further protective measures on the foundation.In this paper,based on the theory of rain infiltration,the analytical solution of the foundation matrix suction under central-peak rainfall infiltration is deduced,and the calculation method of the ultimate bearing capacity of the foundation under central-peak rainfall infiltration is given.The foundation under the central-peak rainfall infiltration is studied.The main content and conclusions are as follows:(1)The derivation and verification of the analytical solution for the suction of homogeneous matrix substrate under the condition of central-peak rainfall.Reasonable assumptions are introduced,a homogeneous foundation model under rainfall infiltration is established,and the initial and boundary conditions of the ground under moderate peak rainfall infiltration are determined based on the characteristics of medium peak rainfall,based on the unsaturated seepage control equation and Gardner model The soil-water characteristic curve and permeability coefficient function in the paper are deduced by the non-homogeneous differential equation method and the positive and inverse change of Laplace to deduce the analytical solution of the foundation matrix suction under medium peak rainfall infiltration.Geo-Studio software was used to verify the correctness of the analytical solution.The results showed that the maximum relative error of the analytical solution and the numerical solution was within 5%,and the matrix suction law changed completely with time,which proved that the derived analytical solution was reasonable and reliable.(2)The calculation method of the ultimate bearing capacity of homogeneous foundation under the condition of medium peak rainfall.Based on the deduced analytical solution of ground matrix suction under the medium-peak rainfall infiltration.The matrix suction distribution during rainfall infiltration was determined,and the average matrix suction within 1.5 times of the base width stress sphere below the base was obtained and embedded in the unsaturated foundation of the Taishaki base strip foundation.The calculation formula of the ultimate bearing capacity of the foundation,and then the calculation method of the ultimate bearing capacity of the foundation during the calculation of peak rainfall infiltration.(3)Research on the evolution law of the suction of the homogeneous foundation matrix and the ultimate bearing capacity of the foundation under the conditions of moderate peak rainfall.Based on the deduced analytical solution of foundation matrix suction and calculation method of ground bearing capacity under deduced medium-peak rainfall infiltration,the comparative analysis of medium-peak rainfall and other three types of rain(uniform,front-peak and back-peak)rainfall.The evolution law of foundation matrix suction and foundation ultimate bearing capacity under infiltration has also been studied.The evolution law of foundation substrate suction and foundation ultimate bearing capacity of different groundwater levels in mid-peak rain rainfall infiltration is also studied.The results show that:1)The matrix suction evolution law before the peak under the mid-peak type is similar to that under the post-peak rainfall,and the matrix suction evolution after the peak is similar to the front peak.2)The four types of rainfall have the same rainfall.Within 6h～12 of the rainfall duration,the foundation matrix under the mid-peak type rainfall infiltration has the largest decrease in suction.At 18h,the ultimate bearing capacity of the foundation under the mid-peak type rainfall infiltration which is the lowest of the four rain types.3)The law of matrix suction evolution of foundations with different groundwater levels under mid-peak rainfall infiltration is roughly the same.In the case of no change in the groundwater level during rainfall,the closer the groundwater level to the surface,the lower the overall substrate suction.The smaller the ultimate bearing capacity,the smaller the difference between the matrix suction at the surface and the matrix suction in the deep soil layer,and the more obvious the rebound of the foundation bearing capacity in the later period of rainfall.(4)Comparative study on the evolution law of foundation matrix suction and ultimate bearing capacity under different medium-peak rainfall conditions.Using the analytical solution of foundation matrix suction under medium peak rainfall infiltration and the calculation method of ultimate bearing capacity,the evolution law of foundation matrix suction and foundation ultimate bearing capacity under different medium peak rain conditions was analyzed.The result shows that:1)The rainfall is the same and the rainfall duration is the same.When the peak time is after the middle time of the total rainfall duration,the presence of a certain peak time makes the maximum decrease of the suction force of the base substrate and the relatively small recovery capacity under the medium peak rainfall infiltration.2)During rainfall,the moment when the ultimate reduction of the ultimate bearing capacity of the foundation occurs the most after the peak.3)The total amount of rainfall is the same,and the peak time is in the middle of the total rainfall duration.The rainfall duration and peak rainfall intensity will affect the bearing capacity of the foundation.4)When the rainfall duration is the same and the peak time is located in the middle of the total rainfall duration,the greater the rainfall,the greater the peak rainfall intensity,and the lower the ultimate bearing capacity of the foundation.