Study On Soft Soil Roadbed Treatment And Hardener Strengthening Soft Soil Mechanical Properties In Coastal Area

Soft soils are widely distributed in our country,most of them are mainly distributed in coastal plains,estuaries and other regions.In recent years,with the rapid economic development,the construction of transportation infrastructure projects in soft soil areas in China has increased.However,due to the characteristics of high natural water content,large porosity,small permeability and high compressibility,soft soils are regarded as "problematic soils" by relevant scholars and engineering technicians.Therefore,the reinforcement of soft soil foundation has very important theoretical and practical significance.In views of these,this paper closely focuses on the urgent needs of the construction and operation of major basic projects in soft soil areas in China,using theoretical analysis to build mathematical models,combining laboratory experiments to explore the basic characteristics,and in-depth study of the effectiveness of pocket manhole and curing agents to improve coastal.Regional soft soil conventional triaxial strength characteristics,triaxial creep characteristics,strength characteristics under different stress paths,dynamic characteristics under automotive cyclic load,etc.,and then evaluate the foundation treatment and the effect of curing agent reinforcement.The main results of this study are as follows:(1)The indoor model test results of pocket manhole show that the pocket manhole method is a very suitable method for the reinforcement of soft soil.The reinforcement effect is very obvious.The initial moisture content of the soft soil and the drainage method have certain reinforcement effects.As a result,the number of pocket manholes is a very important factor.The settlement of 5 bagged sand wells is greater than that when the number is 1,indicating that the more pocket manhole,the more the settlement The larger,the better the reinforcement effect.(2)Based on the indoor triaxial test,the conventional triaxial strength characteristics,triaxial creep characteristics,and strength characteristics under different stress paths of the reinforced soil under different influencing factors were studied.The test results showed that the amount of curing agent,confining pressure,age,water glass mixed The amount has a great influence on the improved soil mechanical properties.When the age increased from 14 d to 28 d,the initial elastic modulus of the curing agent modified soil increased from 60.9k Pa to 191.2k Pa,an increase of about 214%.(3)The conventional triaxial shear test of hardening sand-bearing soft soil in the coastal area showed that the failure stress of the improved soil increased greatly with the increase of dry sand and hardener content,and its residual stress reached 444 k Pa when the dry sand content was 30%.When the amount of curing agent increased from 3% to 9%,the failure stress increased from 236 k Pa to 555 k Pa,an increase of about 135%.The specimens undergo different creep stages under different partial stresses.They undergo stable creep stages,decay creep stages and accelerated creep stages,respectively.(4)Based on the indoor long-term cyclic triaxial test,the evolution of the stiffness and damping ratio of the reinforced soil with the number of load vibrations was studied by different influencing factors(curing agent content,confining pressure,age,water glass content,and load amplitude).The test results show that there is an optimal blending amount of curing agent and water glass.When the curing agent is 15%,the strengthening effect of coastal soft soil is the best.When the blending amount of water glass is 3% When the final stiffness value is slightly higher than the stiffness value when the blending amount is 5%.