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在自由场中设置群桩基础,改变桩基间距,应用FLAC3D作系列三维桩基础非自由场液化数值模拟试验,从桩对液化土的反作用这一方面,研究群桩设置对场地液化分布的影响,揭示群桩抗液化效应。试验结果显示,群桩改变了自由场的特性,群桩非自由液化场水平向不再同性。相对于自由液化场,群桩约束了内部土体自由应变,加大了桩-土结构复合地基的整体抗剪刚度,适当间距的群桩抑制下部土液化的效应较明显,超孔压比降低20%,群桩对上部土体的抗液化效应不大。桩基间距越小对近处场地液化的抑制作用越大,对远处液化的强化作用也越大,桩间距越大抑制作用越小,对远处的强化作用也越小。桩间距相同,桩径加大,桩间场液化度降低。研究成果为桩-土结构复合地基抗液化设计提供理论及试验基础。
The group pile foundation is set up in the free field to change the pile spacing. FLAC3D is used to simulate the non-free-field liquefaction of three-dimensional pile foundation. From the aspect of reaction of the pile to the liquefied soil, , Reveal the anti-liquefaction effect of group pile. The experimental results show that the group pile changes the characteristics of the free field, and the non-free liquefaction field of the group pile is no longer isotropic. Compared with the free liquefaction field, the group pile constrained the free soil internal strain, increased the overall shear stiffness of the composite foundation with pile-soil structure, and the effect of the group pile with proper spacing restraining the liquefaction of the lower soil was more obvious, the excess pore water pressure ratio decreased 20%, group pile on the upper soil anti-liquefaction effect is not big. The smaller the pile spacing is, the greater the inhibition of liquefaction in the near field is and the stronger the strengthening effect on liquefaction in the distance is. The larger the spacing of piles is, the smaller the inhibition is and the less the strengthening effect is to the far site. The same spacing between piles, pile diameter increases, field liquefaction between piles decreases. The research results provide theoretical and experimental basis for anti-liquefaction design of pile-soil composite foundation.