先压桩会对后压桩产生遮拦影响, 后压桩亦会挤压周围土体迫使先压桩发生上浮以 及倾斜, 这些效应都会影响桩基础的承载力和稳定性. 因此, 研究己打入桩对土体位移的遮拦 效应具有很重要的工程价值. 基于模型试验和数字图像相关 (digital image correlation, DIC) 技术, 研究了不同桩间距、砂土粒径、桩壁粗糙度条件下先压桩对后压桩的遮拦效应. 对后 压桩沉桩过程中先压桩桩周土体水平位移进行分析后发现, 随着桩间距的不断增大, 水平方 向的遮拦效应不断减弱. 对不同桩间距水平衰减幅度进行拟合, 可以推测当桩间距达到 6D (D=30 mm) 后, 先压桩对后压桩基本没有遮拦效应. 研究结果发现: 不同粒径土体情况下, 粒 径大小对邻桩的水平遮拦效应影响并不大; 不同粗糙度的桩壁所造成的衰减幅度随着桩壁粗 糙度的降低而不断减小, 说明桩壁越光滑, 遮拦效应越小; 后压桩对桩周土体的挤压会造成先 压桩桩体产生倾斜和上浮, 其中桩间距越小、桩壁越粗糙, 先压桩的水平位移、倾斜角度、上 浮量就越大; 桩周土体粒径越细, 先压桩水平位移和上浮量就越小, 但倾斜角度会变大.

During the construction of a pile foundation, the initial-pressure pile pressing exerts shading effects on the post-pressure pile, and the post-pressure pile displaces and compacts the surrounding soil, causing the initial-pressure pile to float and tilt. These combined effects affect the bearing capacity and stability of the pile foundation. Therefore, it is of great engineering significance to study the shading effect of the piles during soil displacement. Model testing and digital image correlation (DIC) technology were used to investigate the effect of the initial-pressure pile on the post-pressure pile, varying parameters including pile spacing, sand and soil grain size, and pile body roughness. Through an examination of the horizontal displacement of the soil around the initial-pressure pile during the sinking of the post-pressure pile, a reduction was observed in the horizontal the shading effect with increasing pile spacing. By fitting the horizontal attenuation amplitude for various pile spacings, it was inferred that when the pile spacing reaches 6D (D=30 mm), there was basically no shading effect of the initial-pressure pile on the postpressure pile. Varying the soil grain size had no significant impact on the horizontal shading effect of neighboring piles. However, the attenuation amplitude decreased as the pile body roughness decreased, indicating that smoother pile body resulted in smaller shading effects. As the post-pressure pile exerted pressure on the initial-pressure pile, the initial-pressure pile experienced tilting and uplifting. In conclusion, the smaller the pile spacing and the rougher the pile body, the larger the horizontal displacement, tilt angle, and uplift effect on the initial-pressure pile. Moreover, the finer the grain size of the soil around the pile, the smaller the horizontal displacement and uplift effect on the initial-pressure pile, but the larger the tilt angle it experienced.