中文摘要：

针对排桩与土钉相结合的一种新型基坑复合支护形式，研究了土钉施加预应力对其受力变形及整体稳定性的影响。采用ABAQUS有限元软件建立排桩复合土钉支护基坑三维数值模型，模拟分析了土钉预应力施加位置和大小对土体的侧移及沉降、排桩侧移、土钉轴力、排桩桩身弯矩及基坑整体稳定性的影响。结果表明，施加预应力的土钉位置越靠近基坑边坡上部，对限制基坑侧移、减小坑后地表沉降作用越明显，且影响程度随施加的预应力增大而增大：土钉施加预应力使得其他排土钉轴力减小，轴力峰值点后移，且对上一排土钉影响最为明显：土钉施加预应力后，排桩桩身轴力变化很小，排桩复合土钉支护基坑整体稳定性亦基本不变。排桩复合土钉支护可通过对基坑边坡上部土钉施加预应力，以进一步控制基坑变形，土钉施加预应力难以提高支护体系的整体稳定性，但有利于增加排桩间土体的局部稳定性。

英文摘要：

As a new type of bracing structure of foundation pit, row piles and composite soil nailing structure was studied. The influences of prestressed soil nails on stress, deformation and global stability of the row piles and compos- ite soil nailing supporting system were studied. ABAQUS finite element software was used to establish three-dimen- sional finite element model of the row piles and composite soil nailing structure. The effects of prestressed position and size on the soil lateral movement and settlement, row pile lateral displacement, axial-force of soil nails, pile moment and overall stability of foundation pits were simulated and studied. The results showed that prestressed position closer the upper part of the foundation pit slope, the impact of the restriction of lateral displacement and the decrease of ground settlement of the pit is more obvious. Moreover, the influence degree increases with the augment of the pre- stress. Prestressed soil nails can reduce the axial force of the other row of soil nails and retreat the axial force peak point. This law has the most obvious influence on a row of soil nai,ls. After the soil nails prestressed, the change of axi- al force of row piles is very small and the global stability of row piles and composite soil nailing structure also basically remains unchanged. Row piles and composite soil nailing structure can further control the deformation by prestressing the soil nails in the upper of foundation pit. Although it is difficult to improve the global stability of supporting system by prestressing, it is conducive to increase the local stability of the soil between piles.