深厚风化混合岩层中咬合桩的止水控制研究

Study on water-stop control of occlusal piles in deep weathered mixed rock strata

基于东莞国际商务区某基坑,以咬合桩作为止水措施对深厚风化混合岩层进行止水控制研究。通过Abaqus数值模拟,研究咬合桩进入不同风化程度混合岩层下基坑内外渗流场的变化规律,模拟结果表明当咬合桩进入弱透水性的中风化岩层时,具有较好的止水效果;咬合桩的止水效果依赖于桩体之间的密封性,在施工中通过对套管安装、桩的成孔采取控制措施保证咬合桩的垂直度,避免咬合桩之间出现开叉渗水现象;电渗法能够有效地验证咬合桩的止水效果,对于经电渗法检测出的渗漏点,根据渗漏情况采取注浆或背桩补强等方式进行处理,确保基坑在开挖过程中不出现渗漏问题。

Based on a foundation pit in Dongguan International Business District,the water-stop control study was carried out for deep weathered mixed rock formations with occlusal piles as the water-stop form.Through Abaqus numerical simulation,the change law of seepage field inside and outside the foundation pit is studied when the occlusal pile enters the mixed rock layer with different weathering degrees.The simulation results show that when the occlusal pile enters the weakly permeable medium weathered rock layer,it has a good water-stop effect;the occlusal pile the water-stopping effect depends on the tightness between the piles.During the construction,control measures are taken for the casing installation and the hole formation of the piles to ensure the verticality of the occlusal piles,and try to avoid the phenomenon of splitting and water seepage between the occlusal piles.The infiltration method can effectively verify the water-stopping effect of the occlusal pile.For the leakage points detected by the electroosmotic method,grouting or back pile reinforcement should be used according to the leakage situation to ensure that the foundation pit is well maintained during the excavation process.No leakage problems occurred.