Evolution Law Of Bearing Capacity And Intelligent Optimization Design Of Reinforced Soil-cement Pile Composite Foundation

Reinforced soil-cement pile is a new kind of foundation reinforcement technology,which can be widely used in soft soil foundation reinforcement in civil engineering.Soil-cement in the reinforced soil-cement pile composite foundation has a complex and slow hardening mechanism,its mechanical properties will evolve with age,resulting in the bearing capacity of the reinforced soil-cement pile composite foundation also evolves with age of cement-soil.In addition,the traditional optimization design method is no longer applicable because of the complexity of settlement calculation.Therefore,with the support of the National Natural Science Foundation(51978254)and Changsha Science and Technology Project(kq2004013),this paper carried out a systematic and in-depth study on the evolution law of mechanical properties of soil-cement and the evolution law of bearing capacity and optimization design method of short core soilcement pile composite foundation.The main efforts and achievements of this paper are as follows.(1)Through in-depth literature mining,laboratory test data of unconfined compressive strength of clay soil-cement with cement ratio between 10% and 25% and age between 3 days and 90 days were obtained.Based on the Bootstrap method of neighborhood uniform sampling proposed in this paper,the mean values and confidence intervals of unconfined compressive strength of soil-launched soil at different ages were estimated,and the hyperbolic evolution equation of unconfined compressive strength of soil-cement was established by regression analysis of the estimated results using hyperbolic function model.(2)Based on literature data mining,laboratory test data of shear strength index and modulus of soil-cement with cement ratio between 10% and 25% and age range from 3 days to 90 days were obtained.The Bayesian Bootstrap method is introduced to estimate the mean value and confidence interval of shear strength index(cohesion and internal friction angle)and modulus of soil at different ages.An improved interval regression analysis method was proposed,and the regression analysis of the estimated results was carried out by using this method,and then the evolution equations of shear strength index and modulus of soil-cement were established.(3)The three-dimensional finite element analysis model of short core cement-soil pile composite foundation is established,and the correctness of the model is verified.The calculation parameters are determined according to the mechanical property parameter evolution equation of cement-soil established in this paper.Through finite element numerical simulation,the load settlement curve and ultimate bearing capacity of short core cement-soil pile composite foundation at different ages are obtained,and then the evolution equation of ultimate bearing capacity of short core soil-cement pile composite foundation with age is established through regression analysis.(4)The inner core diameter,outer core diameter,inner core length,outer core length and pile spacing are used as test factors for uniform test design,and the settlement value of rigid core cement soil pile composite foundation is calculated by numerical analysis,Kriging settlement agent model is constructed,and then the optimization design mathematical model with the engineering cost of rigid core cement soil pile composite foundation as the objective function is constructed.The cuckoo algorithm is introduced to solve it,and a bionic intelligent optimization design method of composite foundation with rigid core cement soil pile is proposed.