水泥改良淤泥质土力学特性及本构模型研究OA

To investigate the mechanical properties of cement-modified silty soil,laboratory tests are conducted to systematically study the influence of initial water content,cement content,freezing temperature,confining pressure and freeze-thaw cycles on the compressive strength of cement-modified soil.Based on the test results,the Duncan-Chang model is modified.The research results of the tunnel construction by artificial freezing method in the cross-river section of Fuzhou Metro indicate that:(a)the compressive strength of cement-modified silty soil initially increases and then decreases with the increase of water content,and peaks to 8.53 MPa when the water content is 28%;(b)the compressive strength of cement-modified silty soil is significantly improved with higher cement content,and reaches 13.05 MPa at 20%cement content,and the stress-strain curve exhibits strain-softening characteristics under high cement content;(c)lower freezing temperatures and higher confining pressures notably enhance the compressive strength,and the compressive strength reaches 8.85 MPa at-15℃and 11.05 MPa under 1.0 MPa confining pressure;(d)freeze-thaw cycles lead to strength degradation,but increasing cement content can mitigate this effect,and at 10%cement content,the strength after freeze-thaw cycles remains higher than that of non-cement group,and the influence of curing age is greater than that of freeze-thaw cycles;and(e)the modified Duncan-Chang model can effectively predict the stress-strain curves under different cement contents.The research findings can provide theoretical support for the design optimization of grouting reinforcement technology in tunnel engineering using the freezing method and soft soil foundation treatment.