桩侧桩端联合后注浆提高承载力及其数值模拟

Post-grouting on the tip and side for ultimate bearing capacity improvement of the foundation pile and its numerical simulation

某高层建筑自重荷载大,对基桩承载力要求高,对该工程桩侧桩端联合后注浆提高基桩承载力的10根试验桩和2根未注浆的锚桩进行了现场检测试验,并在FLAC3D中分别用土体参数、桩土界面参数和等效桩径模拟后注浆提高基桩承载力的机理。结果表明:联合后注浆桩的桩长满足要求,桩身完整;后注浆比未注浆的基桩承载力提高70%以上;将单桩竖向极限承载力取为8800kN是偏于安全的;注浆压力和注浆量、土体的性质对后注浆提高基桩承载力的影响较大,后注浆结石体性质对桩承载力的影响相对较小;用等效桩径法可有效模拟后注浆提高桩承载力的机理。

The construction of post-grouting on the tip and side for ultimate bearing capacity improvement in one high-rise building which is located on the medium-soft soil site is presented,the 10 piles with post-grouting on tip and side and 2 unpost-grouting piles are tested and analyzed,and the different parameters of the ground,the interface of pile and peripheral soil and post-grouting equivalent pile diameter are adopted to simulate the mechanics of post-grouting improvement the pile bearing capacity in FLAC3D program.The rusults indicated that the length and integrity of piles are satisfying;the untimate bearing capacity of post-grouting piles are 70% improved at least than that of unpost-grouting piles,designing single pile ultimate bearing capacity as 8800kN is secure;the post-grouting volume,grouting pressure and the parameter of peripheral soil are the important influencing factors for pile bearing capacity improvement by post-grouting,the properties of grouting and soil concretion is little influnce to pile bearing capacity,but post-grouting equivalent pile diameter can effectively simulate the mechanics of post-grouting improvement the pile vertical bearing capacity.