掺碎石改良宽度对膨胀土侧向膨胀力影响研究

Study on the influence of modified width of gravel on lateral swelling force of expansive soil

为研究掺碎石膨胀土作为挡土墙填料时的改良宽度对挡土墙稳定性的影响,通过自制模型箱模拟刚性挡土墙,以广西南宁三塘地区膨胀土为填料,以碎石为改良材料,分别探究体积含水率和侧向膨胀力在不同填料改良宽度时的变化规律。研究结果表明:纯膨胀土渗透性很差,水分难以入渗而汇集在墙顶产生额外压力影响挡墙稳定性,在经掺碎石改良后随着掺碎石宽度越宽,水入渗越快;膨胀土在浸水和膨胀变形受限的情况下会产生侧向膨胀力,其变化与体积含水率呈正相关,但存在一定滞后现象,随着掺碎石改良宽度越宽,体积含水率和侧向膨胀力的变化越快,滞后时间越短;掺碎石改良膨胀土能有效削弱膨胀土侧向膨胀力,随着掺碎石改良宽度越大,膨胀土侧向膨胀力的降低效果越显著。

In order to study the influence of the modified width of expansive soil mixed with crushed stone as the filler of retaining wall on the stability of the retaining wall,the customized model box was used to simulate the rigid retaining wall,and the expansive soil in Santang area was obtained for use from Nanning,Guangxi as the filler.The crushed stone was used as the materials for improvement,and the variation of volumetric moisture content and lateral expansive force at different improved widths of fillers was studied,respectively.Testing results show that the permeability of pure expansive soil is very poor,water is difficult to infiltrate into the soil and collect on the top of wall to produce additional pressure which affects the stability of the retaining wall,and the water infiltration is faster when improved materials by mixing crushed stone to widen the width of mixed crushed stone filler.The expansive soil will produce lateral expansion force when the expansive soil is under the condition of water immersion and limited expansion deformation. The change rate is positively correlated withthe volume moisture content, but there is a certain hysteresis, and the hysteresis time is shorter and the change ofvolume moisture content and lateral expansive force is faster when the wider the width of crushed stone filler.Improved expansive soil mixed with crushed stone can effectively weaken the lateral swelling force of expansivesoil, and the reduction of lateral expansive force of expansive soil is more obvious with the improved width ofmixed crushed stone filler increasing.