Numerical Analysis Of Microscopic-mechanical Properties Of Reinforcing Materials For Soft Soil Foundation

After years of development,China’s construction industry has begun to enter a new urban construction stage,and improving the city’s appearance and living environment has become a strong desire of the people.However,some developed areas are often close to rivers,lakes,and seas,which makes large areas of soft ground exist.For highways,slopes,and foundation pits,due to its high compressibility and low water permeability,soft ground is prone to uneven settlement and is extremely harmful.Therefore,the reinforcement of the soft soil foundation is particularly important in the construction of new cities in China.Particle-reinforced cement-based composite materials are often used for internal and external reinforcement of soft ground.The internal reinforcement material sand-mixed cement-soil mixing pile has attracted much attention because of its low cost,wide application range and good reinforcement effect.The new graphene oxidereinforced cement-based composite material has good development prospects in the external reinforcement of soft soil foundations.Since the functional group of graphene oxide can regulate the formation of cement hydration products and reduce the porosity of the cement matrix,it has great potential to improve the mechanical properties of the cement matrix and the situation of surface cracking.In order to study the reinforcement mechanism of these two particle-reinforced composite materials,it is particularly important to analyze the influence of the interphase and reinforcement on the macroscopic mechanical properties of the composite material from a microscopic perspective.The research content of this paper consists of two parts.The first part of the research object is the material of the reinforced sand-mixed cement-soil mixing pile inside the soft soil foundation.The second part of the research object is the graphene oxide material of the external cement-based plaster of the soft ground Reinforcement of cement-based composite materials.In order to study the interphase and reinforced phase effects of the microstructure of sand-sanded cement-soil composites,a two-dimensional three-phase numerical structure model including the interphase,the reinforced phase and the matrix was established.Compared with the experimental results,parameter correction and model verification were carried out on the numerical model.Finally,the geometric and mechanical properties of the microscopic interphase and the reinforced phase were studied using a two-dimensional three-phase numerical model.The results show that the interphase effect of the sand-soil cement-soil composite cannot be ignored.The increase of the interphase’s normal elastic modulus and the decrease of the interphase’s average thickness significantly improve the mechanical properties of the composite.It should be the focus of research in practical engineering.In addition,the peak stress at the interphase of sand-cemented soil is very small,and its increase will obviously improve the macroscopic mechanical properties of the composite.When it reaches a certain critical value,its impact on the macroscopic compressive strength is very weak.In order to study the geometric and mechanical properties of the reinforced phases and interphases of the microstructure of graphene oxide reinforced cement-based composites,a three-dimensional three-dimensional representative volume unit numerical model was established in this paper.Based on the experimental results of graphene oxide reinforced cement-based composite materials,the three-dimensional three-phase numerical structure model was corrected for cement-based parameters.The numerical results of the effective elastic modulus are compared with the Mori-Tanaka theoretical results to verify the feasibility of the three-dimensional three-phase graphene oxide reinforced cement-based numerical model.Finally,the three-dimensional three-phase numerical structure model was used to analyze the reinforced phase and interphase parameters of graphene oxide.The results show that when graphene oxide is ideally distributed in the cement matrix,the volume fraction and aspect ratio(diameter to thickness)of graphene oxide have a significant effect on the macroscopic mechanical properties of the composite.And the influence of interphase normal elastic modulus is very weak.