Study On The Mechanical Properties And Freeze-thaw Damage Constitutive Model Of Deep Expansive Clay

In recent years,China has been a big energy demand country in the world,the demand for coal resources is only increasing,and the depth of coal mining is deepening.In the process of mine construction,the deep clay with expansibility is often encountered.In the process of freezing construction,because of the joint action of soil expansibility and freeze-thaw cycle,the freezing pipe often breaks,the shaft wall cracks,water leakage and other problems.It brings a great challenge to the exploitation of coal resources.Based on the existence of such problems,this paper takes the deep expansive clay under the air shaft inspection hole of a mine in Anhui Province as the research object,and studies the physical and mechanical characteristics of the deep expansive clay and the derivation and verification of the damage constitutive equation under the action of freeze-thaw cycle in three aspects:laboratory test,theoretical derivation and result verification.Through the laboratory test of the deep soil sampled in the field,it is found that the physical indexes of the deep expansive clay,natural moisture content and natural density are most closely related to the depth.The expansion of deep expansive clay can be divided into three stages,and the expansion performance is closely related to the initial moisture content and the applied load;the volume frost heave rate and the linear frost heave rate of deep PENGCHANG clay are affected by the moisture content,and the volume frost heave rate can better reflect the frost heave performance of soil;the stress-strain curve of deep expansive clay is generally stress-strain curve at low confining pressure or low moisture content However,with the increase of water content,strain hardening appears.The increase of freeze-thaw times leads to the obvious deterioration of the mechanical properties of the soil;the triaxial compressive strength of deep expansive clay under the combined action of freeze-thaw cycle and load conforms to the Weibull distribution,and the damage constitutive equation derived from it is verified to be consistent with the actual data base.It is hoped that the research results of this paper can provide valuable reference for the construction and prediction of mine shaft wall in the future.Figure[41]table[17]reference[75]...