淤泥质土及其改良土体动力特性试验研究

为探究佛山淤泥质土及掺加超细水泥改良土体的动力特性,依托佛山地铁2号线一期工程,对隧址区内的淤泥质土及掺加超细水泥的改良土体进行动三轴试验。研究结果表明:相同围压条件下,随超细水泥掺量增加,土体抗剪强度增大,动剪切模量增大,最大阻尼比减小;对于同一土样,随围压增大,土体抗剪强度增大,动剪切模量不断增大;不同围压条件下的阻尼比随剪应变的变化均可分为两个阶段,当剪应变较小时,阻尼比与围压呈负相关,在剪应变较大时,阻尼比与围压呈正相关;掺加超细水泥对淤泥质土具有较好的改良效果,掺加超细水泥400 kg/m~3土体的动黏聚力为4.4～7.5 kPa,动内摩擦角大小为1.9°～5.16°。本文测定出淤泥质土原状土及改良土体在振动作用下的各项参数,为研究隧道长期不均匀沉降特性提供基础数据。

Experimental Study on Dynamic Characteristics of Muddy Soil and Modified Soil

In order to explore the dynamic characteristics of the muddy soil and the modified soil with superfine cement, dynamic triaxial test is carried out on the muddy soil and the improved soil mixed with superfine cement based on Foshan Metro Line 2 phase-1 project. The results show that under the same confining pressure condition, with the increase of superfine cement content, the shear strength of the soil increases, the dynamic shear modulus decreases and the maximum damping ratio decreases. For the same soil sample, with the increase of confining pressure, the shear strength of the soil increases, and the dynamic shear modulus increases continuously. For the same soil sample, the shear strength of the soil increases and the dynamic shear modulus increases continuously with the increase of the confining pressure. The variation of damping ratio with the change of shear strain under different confining pressures can be divided into two stages: when the shear strain is small, the damping ratio is negatively correlated with the confining pressure; when the shear strain is large, the damping ratio is positively correlated with the confining pressure. Adding superfine cement has better improvement effect on muddy soil. The dynamic cohesion of the soil with 400 kg of superfine cement is 4.4～7.5 kPa, and the internal friction angle is 1.9°～5.16°. In this paper, the parameters of muddy soil and modified soil under vibration are determined, which provides basic data for the study of long-term uneven settlement of tunnels.