陀螺桩垫层加强袋装砂井排水地基现场试验

常规袋装砂井排水的软土地基要求缓慢加荷因而占用了较多工期不利于工后沉降控制。为加快袋装砂井排水地基的加荷速率开展陀螺桩垫层加强袋装砂井排水地基现场试验。研究表明:陀螺桩垫层可以提高地基的整体稳定性,在快速加荷导致软土孔压系数B值大于1的条件下保持地基稳定;陀螺桩垫层降低了地基浅部高压缩性土层的压缩量,相对增大了软土层下无排水体土层的压缩量,抑制软土侧向变形的发展,降低工后沉降的速率;陀螺桩垫层降低了压缩层中的孔压峰值,使软土固结过程加快;相对于砂垫层陀螺桩垫层具有更大刚度,导致上部荷载在地基中产生的附加应力分布型式发生显著变化,使得袋装砂井排水地基的综合性状得到加强。

Field tests on top-shaped concrete block cushion-reinforced soft soil foundation drained with sand bag well

The soft soil foundation drained by the conventional sand bag wells requires slow loading,which occupies more construction period and is not conducive to post-construction settlement control.In order to accelerate the loading rate of the drainage foundation of sand bag wells,field tests on the top-shaped concrete blocks-reinforced drainage foundation of sand bag wells are conducted.The research shows that the top-shaped concrete blocks can improve the overall stability of the foundation,and keep the foundation stable under the condition that the rapid loading causes the value of the pore pressure coefficient B of soft soil to be greater than 1.The top-shaped concrete blocks reduce the high-compressibility soil in the shallow part of the foundation.The compression of the layer relatively increases the compression of the undrained soil layer under the soft soil layer,inhibits the development of lateral deformation of the soft soil,and reduces the rate of post-construction settlement.The top-shaped concrete block layer reduces the pore pressure in the compression layer,and the peak value accelerates the consolidation process of soft soil.The top-shaped concrete blocks have greater rigidity than the sand cushions,resulting in a significant change in the type of additional stress distribution generated by the upper load in the foundation,leading to that the comprehensive behavior of the drainage sandbag ground is strengthened.