粉质粘土中的刚性桩在横向载荷作用下失稳的模型试验研究

为解释横向载荷作用下刚性桩的失稳机理，针对桩头自由的刚性桩做了一系列横向加载试验。基础土为粉质粘土，含水量介于9.85 %～13.85 %之间。由载荷-位移全过程曲线发现，刚性桩在横向载荷达到一定值时会失稳；由试验录像及土体剖面发现，由于土体的软化破坏，在桩后土体内会出现贯穿的局部破坏并形成一楔体，同时在土面伴随一不完全的椭圆形鼓包及一条平行于加载方向的拉伸裂缝，而在桩前土中，由于桩的挤压会形成一条侵彻沟。分析认为，对大位移刚性桩桩后土体的破坏是桩失稳的根本原因。

Experimental study on instability of rigid piles under lateral loads in silty clay

A series of tests on free-headed rigid piles were carried out in order to explain the instability mechanism of rigid piles under lateral loads. The soil used was unsaturated remolded silty clay. The water content of soil was between 9.85% and 13.85%. The total process load-displacement curve indicated that rigid piles would be instable when lateral loads attained to a certain amount. Visual records and soil sections showed that one shear band and one wedge were formed in the soil behind a pile with the softening failure of soil, along with one incomplete elliptic bulging and one tension crack parallel to the load direction on the soil surface. In the soil before a pile, one penetration groove was formed owing to the extrusion of the pile. The formation of the shear band is the essential reason of the instability of a rigid pile. And the extrusion failure of the soil before pile can't play a decisive role in the instability of a rigid pile. As to rigid piles with large displacement, the essential reason of the instability is the failure of the soil mass behind piles.