桩-土-承台共同作用的模型试验研究

通过带承台单桩及双桩基础的模型试验,对低承台桩基桩间土变形发展及其与承台板板底应力、桩侧摩阻力及桩端阻力间的相互影响进行较为细致的研究。试验表明:在相同基础荷载作用下,桩数的增加使桩端刺入变形量占基础沉降的比例降低。双桩基础桩体的存在对板底应力体现出增强作用,在相同桩间土变形量下,双桩基础板底应力大于带承台单桩基础。桩土相对位移的发展从桩端部位开始,逐步向承台板扩展,同一部位基础外侧的桩土相对位移要大于基础内侧。靠基础内外,桩的不同侧面表现出不同的侧阻发挥过程及极限值。同样桩间土变形量下,带承台双桩基础在桩端平面上土体的竖向应力要大于带承台单桩基础,从而发挥出较大的桩端阻力。

Model tests on pile-soil-cap interaction

The results of model tests on pile-soil-cap interaction were presented. The soil displacement among the piles, contact pressure on the base of the cap, pile shaft and toe resistance were studied. It was observed that the ratio of pile toe penetration to foundation settlement decreased with the increase of pile number under the same foundation loading. With the same soil displacement among the piles, the contact pressure on the base of pile cap was larger for the foundation with two piles than that with single pile because of the enhancing function of the two piles on the soil capacity beneath the pile cap. The relative displacement between pile and soils around pile shaft was developed from the pile toe and gradually spread to near the pile cap. The relative displacement between pile and soils around pile shaft outside the foundation was larger than inside the foundation at the same depth. The mobilization of shaft resistance and its ultimate value of the shaft inside the foundation were different with those outside the foundation. With the same soil displacement among the piles, the vertical soil stress at the depth of pile toe was larger for the foundation with two piles than that with sing pile, which resulted in larger toe resistance for the foundation with two piles.