蒙辽客运专线粉砂地基固结压缩特性的三轴试验研究

Tri-axial Test Study of the Consolidation and Compressibility of Silty Sand in Mongolia ~ Liaoning Dedicated Passenger Railway

依托新建通辽至京沈高铁新民北站铁路路基工程,对细颗粒含量分别为10%、15%、30%和40%的中密状态粉砂开展一系列室内固结不排水三轴试验研究,通过试验研究不同细颗粒含量粉砂在不同围压条件下的应力-应变关系、孔隙水压力的涨消发展模型及初始剪切模量的发展规律,揭示细颗粒含量和围压对中密状态粉砂应力-应变关系、孔压演化特性及初始剪切模量的影响规律。结果表明:空间应力状态下的不同细颗粒含量中密粉砂的应力-应变关系曲线以硬化型为主,符合增长型双曲线模式,且随着围压的增加,应力-应变关系曲线呈现强硬化状态,随着细颗粒含量的增加,应力-应变关系曲线呈现弱硬化状态。孔隙水压力的变化表现为随剪切的发展先经过一段上升过程,达到峰值后又开始下降,且随着细颗粒含量的增加,围压的增大,孔压的峰值越高,孔压消散速度降低,剪切完成后的残余孔压越大。初始剪切模量与围压呈正相关,即随着围压的增大而增大。同时,运用ABAQUS有限元程序建立计算机模型模拟试验,进一步验证上述分析结果的真实性与可靠性。

Based on the subgrade engineering of the new Tongliao to Xinmin North Station of BeijingShenyang High Speed Railway,a series of in-house tri-axial tests under the condition of consolidation and non-drainage are carried out to study the stress-strain relationship and the development law of the pore water pressure of the medium dense silty sand with 10%,15%,30% and 40% of fine particles.The influences of different fine particle contentson the developing characteristics of pore water pressure of the medium dense silty sand under different confining pressures are demonstrated.The experimental results show that,the stress and strain curve of the medium dense silty sand under the condition of spatial stress tends to show a strong hardening state with the increase of the confining pressure and in a weak hardening state with the increase of the fine article content.Along with the development of shear,the variation of pore water pressure increases firstly and then drops after the peak value is reached.In addition,with the increase of the fine particle content and confining pressure,the peak pore pressure increases and the dissipation rate of pore water pressure decreases showing a trend of delay and greater residual pore pressure; the initial shear modulus is positively correlated to the confining pressure and increases with the increase of confining pressure.Meanwhile,the authenticity and reliability of the above experimental results are proved by using a computer model test base on finite analytical procedure ABAQUS.