韩冬卿 葛辰贺

摘要 基于位移加载法模拟微型钢管桩受力性能，综合分析了加载过程中，桩长L、桩体数量N、桩间距S、桩体排布形式、嵌岩深度等因素对单、群桩力学性能和群桩效应的影响。研究结果表明：单桩极限承载力随着桩长增加逐渐增加，;群桩最大轴力变化规律：角桩>边桩>中心桩;同等条件下，增加桩数量，承载力和群桩效应系数η相应增大;桩数不变，承载力随桩间距增大而增大，群桩效应系数逐渐减小，桩间距等于5倍桩径（S = 5D）时承载力和群桩效应系数均趋于稳定，故S = 5D为临界桩间距;梅花形排布方式比矩形排布平均单桩承载力提升高4.7%，群桩效应系数降低10.2%;嵌岩深度增加，单、群桩极限承载力增加且幅度较小，故嵌岩深度对单、群桩承载能力影响不明显。

关 键 词 微型钢管桩;数值模拟;群桩效应;位移加载;极限承载力

中图分类号 TU 473.13     文献标志码 A

Abstract Based on the displacement loading method， the mechanical behaviors of micro-steel piles were simulated. The factors such as the numbers of piles N， the spacing of piles S， the arrangement of piles， the depth of rock-socketed and the elastic modulus of rock mass were analyzed. The results show that the ultimate bearing capacity of a single pile increases with the length L; Keeping other parameters identical， increase the number of piles， the bearing capacity and group pile effect coefficient increase correspondingly. The number of piles is unchanged， the bearing capacity increases with the increase of pile spacing， the pile group effect coefficient decreases gradually， when pile spacing equals 5 times pile diameter（S = 5D）the bearing capacity and group pile effect coefficient η tend to be stable， so S = 5D is critical pile spacing. The average single pile bearing capacity of blossom arrangement is 4.7% higher than the rectangular arrangement， and group effect coefficient decreases by 10.2%， so the blossom arrangement is better; With the increases of depth of embedded rock modulus， and ultimate bearing capacity of single and group piles has increased a little . Therefore， the effect of rock-socketed depth on the bearing capacity of single and group piles is not obvious.

Key words micro-steel-pipe pile; numerical simulation; group pile effect; displacement loading; ultimate bearing capacity

0 引言

注漿微型钢管桩属于微型桩的一种，自20世纪50年代由意大利学者Lizzi提出微型桩概念以来[1]，微型桩在岩土工程领域得到了广泛应用。这类微型桩直径一般不大于300 mm且长细比大于30，因其桩径小、施工方便、承载力高和扰动小等优异的工程特性而被广泛用于滑坡治理、基坑支护和既有房屋基础加固处理中[2-4]。目前，对于微型钢管桩承载特性的研究，更多的是参照普通灌注桩[5-6]。对于以微型钢管桩单、群桩作为建筑物如桥梁基础的综合承载特性的分析相对较少。陈少博[7]基于静载试验和数值模拟对比分析微型钢管桩的单桩破坏模式和承载力，指出失稳是主要破坏模式，并分析了桩长对微型钢管桩承载特性的影响。程赛……