水泥固化滨海风积砂力学特性试验及细观数值仿真

滨海风积砂因结构松散、自稳能力差、级配不良不易压实,被视为一种特殊土。水泥固化是常用的加固手段,而水泥剂量对风积砂力学性能的影响规律及细观作用机制目前尚不清楚。利用GDS土工三轴试验仪,对不同水泥剂量(0%,4%,6%)的水泥固化滨海风积砂进行不同有效围压(50,100,150 k Pa)下的CD试验。结合室内试验数据和水泥砂样显微照片,建立水泥固化滨海风积砂细观结构的颗粒流PFC2D模型,进行三轴试验的细观数值仿真分析。研究结果表明,水泥固化滨海风积砂应力–应变关系呈应变软化型,水泥剂量对滨海风积砂强度贡献明显,对体变影响相对较小。采用颗粒平行黏结方式的颗粒流数值仿真能有效反映水泥固化滨海风积砂的细观力学特性,水泥剂量对水泥固化滨海风积砂的黏结破坏数、配位数、位移场均有显著影响。

Experimental study on mechanical properties and mesoscopic numerical simulation of cement-solidified coastal aeolian sands

Coastal aeolian sand is treated as a kind of special soil for its loose structure, poor stability and poor gradation. Cement solidification is a common method for strengthening. However, the influence rule and microscopic mechanism of cement dosage on the mechanical properties of aeolian sand are still unclear. The CD tests under various effective confining pressures (50, 100 and 150 kPa) on aeolian sand solidified by different amounts (0%, 4% and 6%) of cement are carried out using GDS triaxial apparatus. Based on the micrograph of cemented sand and experimental data, the microstructural models for cemented coastal aeolian sand are established using PFC^2D. The mesoscopic numerical analysis of triaxial tests is presented. The results show that the cemented coastal aeolian sand is strain-softened. And the cement dosage makes great contribution to the strength of coastal aeolian sand, but less influence on the volumetric strain. The PFC model with parallel connection can effectively reflect the main mechanical behaviors of cemented coastal aeolian sand. The cement dosage has a significant impact on bond-breaking number, coordination number and displacement field for the cemented coastal aeolian sand.