嵌岩桩竖向抗压承载力试验研究

Experimental study on vertical compressive bearing capacity of rock-socketed piles

嵌岩桩基础的竖向承载力受多种因素影响,包括桩身强度、桩侧土质条件、入土深度、基岩的岩性等。《建筑桩基技术规范》(JGJ 94-2008)规定:对于受竖向荷载较大的设计等级为甲级、乙级的建筑桩基,单桩竖向承载力特征值应通过单桩静载试验确定。某工程开展结构设计前,对冲孔灌注的嵌岩桩进行了低应变桩身完整性测试和单桩竖向抗压静载试验,并量测了试验过程中基桩的内力、位移等参数。通过对试验数据的整理、分析得出以下结论:桩承载力的最主要的影响因素是桩身强度;嵌岩桩桩端未发挥全部承载能力;桩的成桩质量是影响嵌岩桩竖向承载力的最关键因素;新回填土未完成沉降,未产生正摩阻力,工程桩可能会产生负摩阻力;均匀土侧摩阻力基随上部荷载基本呈线性变化,非均匀粒径的桩周土侧摩阻力呈较大的离散性。

The vertical bearing capacity of rock-socketed pile foundation is affected by many factors, including end resistance, side resistance, pile body strength and construction quality. "Technical Specifications for Building Pile Foundations"(JGJ94-2008) stipulates: For building pile foundations with design grades A and B that are subjected to large vertical loads, the characteristic value of the vertical bearing capacity of a single pile shall pass the static load of a single pile. Test confirmed. Before the structural design of a project, the low-strain pile integrity test and the vertical compressive static load test of the single pile were carried out on the punched rock-socketed pile, and the internal force and displacement of the foundation pile during the test were measured. Through the sorting and analysis of the test data,the following conclusions are drawn: the end of the rock-socketed pile does not exert its full bearing capacity;the most important factor affecting the bearing capacity of the pile is the strength of the pile body;the pile quality of the pile affects the bearing capacity of the rock-socketed pile. The most critical factor;the new backfill failed to complete the settlement, resulting in a large negative friction, reducing the ability of the pile foundation to bear the upper load;uniform soil side friction increases with the increase of the upper load;non-uniform particle size The lateral friction resistance of soil around the pile has high discreteness.