灰土挤密桩加固湿陷性黄土地基效果分析

Effect Analysis of Lime-soil Compaction Pile Reinforcing Collapsible Loess Foundation

为研究灰土挤密桩处理湿陷性黄土地基的施工控制参数,确保地基处理效果,依托兰临高速公路湿陷性黄土地基处理工程,通过现场取样及物理力学性质试验,研究湿陷性黄土地基在加固前后的含水状态、孔隙特征、压缩特性、湿陷性等随空间分布变化规律,运用圆孔扩张理论分析桩间土剪胀特性、初始应力对塑性区半径的影响。结果表明:桩间土含水率随其与桩体距离的增大而增大,而随深度增加而减小;桩间土干密度、压缩模量随距桩体水平距离的增大而减小,孔隙比的规律则相反;在距桩身0.7 m半径范围内桩间土的湿陷性已消除;塑性区半径随剪胀参数的增加而增大,随深度的增大而减小。研究结果得出石灰掺量为10%、桩径为0.4 m时,灰土挤密桩处理湿陷性黄土地基的合理桩间距宜取1.3 m。

In order to investigate the construction control parameters for treating collapsible loess foundation using lime-soil compaction piles and ensure the effectiveness of the treatment,focuses on the foundation treatment project of the Lan-Lin Expressway,through the physical and mechanical properties test studied the water content,pore characteristics,compression characteristics and collapsibility of collapsible loess foundation soil samples with spatial distribution before and after reinforcement,and the influence of dilatancy characteristics and initial stress on the radius of plastic zone was analyzed by using the theory of cavity expansion.The results indicate that moisture content in soil between piles increases with distance from piles but decreases with depth;dry density and compression modulus decrease with horizontal distance from piles,while porosity shows an opposite trend,collapsibility within a 0.7 m radius from pile bodies is eliminated,the radius of plastic zone increases with dilatancy parameter but decreases with depth increase.Results suggest that when lime content is 10%and pile diameter is 0.4 m,a reasonable spacing for lime-soil compaction piles treating collapsible loess foundation is 1.3 m.