Structural Mechanical Properties Of The Solidification Light Soil In The Combination Of Freeze-thaw And Cyclic Loading

With the increasing production of urban sludge,the destruction of the ecological environment has become increasingly serious,and a new type of sludge light curing technology has emerged.This technology has a very good solidification effect on sludge,which can not only protect the environmental but also have good mechanical properties to meet the needs of practical projects.In this paper,based on the physical and mechanical properties of sludge-cured lightweight soils,the strength and deformation characteristics under freezing and thawing action,cyclic loading,and their effects on the structural properties of solidified soils are studied.And the structural quantitative parameters are put forward.The main research contents and conclusions are as follows:?1?A brief introduction was made to the new sludge-cured lightweight technology when preparing samples in the laboratory.The required materials and equipment are easy to obtain,and the preparation process is simple.The solidified sludge has the characteristics of light weight,high strength,low compressibility,and strong structural properties.It can not only prevent secondary pollution,but also be economical and reasonable.It can be used in subgrade filling,soft ground treatment,landscaping and sponge city projects.?2?Through the consolidation test of solidified soil,remolded soil and saturated soil,the structural properties of the sludge-cured lightweight soil were analyzed based on the comprehensive structural potential m_p.The m_p increases first and then decreases with increasing pressure and gradually stabilizes,reflecting the structural change of solidified soil under pressure.The influence of freezing and thawing on the structural properties of solidified soil was analyzed by the unconfined compressive strength test and the consolidation test.The more the freeze-thaw cycles and the lower the temperature,the weaker of the structural strength.After a certain number of times,the effect of freezing and thawing gradually disappeared.The freeze-thaw structure potential m_pn was proposed to quantitatively analyze the effects of freeze-thaw cycles on the structural size.?3?Dynamic triaxial tests on sludge-cured lightweight soils were carried out.The effects of confining pressure,vibration waveform,vibration frequency and curing age on dynamic structural characteristics were analyzed in terms of deformation and strength.Comparing the test results of dynamic characteristics of solidified soil,remolded soil and saturated soil,structural properties of solidified soil were analyzed based on dynamic stress-strain characteristics,dynamic strength characteristics and dynamic modulus characteristics.The structural parameter m_d?and m_{d E} were proposed to quantitatively reflect the structural change of solidified soil under cyclic loading.?4?Through the dynamic triaxial test results of the solidified soil subjected to freezing and thawing cycles,the effect of freezing and thawing on the structural properties such as dynamic strength and dynamic modulus was analyzed.Based on the dynamic stress-strain relationship of freeze-thaw soil,remolded soil and saturated soil,a structural parameter m_d?n and m_dEn were proposed.This parameter quantitatively analyzes the structural changes of the solidified soil under freezing and thawing and cyclic loading.The larger the value,the better the structural properties of the soil.Comparing the initial value with the stability value,the damage degree of the solidified structure by the freeze-thaw cycles can be obtained.