| Cemented soil is an engineering material formed by a series of complex ch emical and physical reactions such as hydration and hardening after cement,water and soil are fully mixed according to a certain proportion.Over the years,cemented soil has become one of the important materials in China’s engineering construction becaus e of its small pollution,flexible reinforcement form and high economic benefits,and has been widely used in foundation reinforcement,foundation pit support,anti-seepage and plugging.In practical engineering,due to the differences of site temperature,humidity and groundwater,cemented soil serves in a complex water-temperature coupling environment,and its mechanical properties develop and change with time,which directly affects the engineering performance and reliability.Therefore,it is of great theoretical and practical significance to deeply study the influence of water-temperature coupling environment on the mechanical properties and evolution law of cemented soil.However,most domestic and foreign scholars study the internal factors of materials such as mix proportion and moisture content,and there are relatively few studies on environmental factors.The influence of water-temperature environmental effect on the mechanical properties and evolution law of cemented soil is not clear.Therefore,this paper has carried out a series of experimental research and theoretical analysis on cemented soil cured in different water-temperature coupling environments.The main work and research results of this paper are as follows:Firstly,the unconfined compressive strength tests of 40 groups of cemented soil samples at different temperatures and ages in water bath environment were designed and completed,and the corresponding stress-strain curve,unconfined compressive strength and deformation modulus E50 were obtained.The effects of temperature on cemented soil strength,E50 and its evolution law were studied,and relevant engineering suggestions were given.Then,based on the mass action theorem in chemical reaction dynamics,the evolution law and function form of unconfined compressive strength of cemented soil with age were deduced.Based on the regression analysis of the test results,the evolution equations of unconfined compressiv e strength and deformation modulus E50of cemented soil considering the influence of temperature were established respectively.The reliability of the evolution equations was verified by comparative analysis with the test data.At the same time,the evolutio n law of cemented soil strength under high temperature was studied,and a new strength attenuation evolution formula of cemented soil was proposed.Secondly,the unconfined compressive strength tests of 75 groups of cemented soil samples under different humidity,temperature and age in air environment were designed and completed.The influence laws of age,temperature and humidity on the stress-strain curve,unconfined compressive strength and deformation modulus E50 of cemented soil were studied by controlling variable method,and analyzing the internal mechanism of the influence of temperature-humidity coupling environment on the strength of cemented soil.Finally,based on BP neural network,the prediction model of unconfined compressive strength and defo rmation modulus E50 of cemented soil under temperature humidity coupling environment was established by introducing combined characteristic variables.The engineering application feasibility of using BP neural network to predict cemented soil strength was verified through error analysis,and the weight and threshold of the prediction model were analyzed to explore the influence of various factors on cemented soil strength.In addition,by comparing E50 prediction models with different network structures,th e effectiveness of introducing combined features to improve the performance of neural network was verified. |
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