反射波法检测超长灌注桩的完整性研究

Research on the Integrity of Super-long Perfusion Piles Detected by Reflection Wave Method

研究目的:软土地区某高速铁路车站旅客地道、站房基础采用反循环法和正循环法施工灌注摩擦桩,桩长60~62 m,桩径1.0 m,C40混凝土灌注,属超长灌注桩;其中有些未设声测管桩的完整性检测采用反射波法,按《铁路工程基桩检测技术规程》TB 10218—2019反射波法规定:桩长一般不大于40 m;当桩长大于40 m时,需要根据现场试验数据确定。因此对其反射波法检测超长灌注桩的完整性进行研究。研究结论:(1)软土地区采用反循环法和正循环法施工的灌注桩,桩端呈扩径状态;(2)首选具有声测管桩进行声波法和反射波法比对试验,均为Ⅰ类合格桩,其反射波桩端曲线呈反向特征,所测速度4280~4320 m/s;(3)选未设声测管桩进行反射波检测,其特征同前一致,钻芯取其完整长度大于0.5 m的芯样做反射波速度测定,速度为4280~4320 m/s,与前者吻合,且芯样抗压强度均达C45,同时做单桩静载试验,满足设计要求;(4)经比对,反射波法检测软土地区超长灌注桩的完整性可行,以此反射波特征参数可指导后续未设声测管桩进行完整性检测;(5)本研究成果可为铁路、公路等领域软土地区反射波法检测超长灌注桩的完整性研究提供参考。

Research purposes:The passenger tunnel foundation of a high-speed railway station in soft soil area adopts the reverse circulation method and positive loops to construct perfusion piles.The pile length is 60~62 m,the pile diameter is 1.0 m.C40 concrete perfusion pile belongs to super-long cast-in-place pile;Some of the non-acoustic tube pile integrity testing use the reflection wave method.According to reflection method of Technical Specification for Testing of Railway Piles TB 10218-2008:The pile length is generally not more than 40 m,and when the pile length is greater than 40 m,the standard of pile length can be determined based on field test data.So the integrality of super-long castin-place pile detection by reflected wave method is studied.Research conclusions:(1)Infusion piles is constructed by reverse circulation and positive loops in soft soil areas,and pile end is in the state of expansion.(2)Firstly,the acoustic wave method and the reflective wave ratio test were selected,both of which were class I qualified piles.The curve of the reflective wave pile was reversed,and the measured speed is 4280 to 4320 m/s.(3)A small number of non-acoustic tube piles are selected to detect the reflection wave with the same characteristics as before,and the core of the drill core is measured by the core sample with a complete length of more than 0.5 m,the speed is 4280 to 4320 m/s,which is consistent with the former.The compressive strength of the core sample is up to C45 concrete,and the static load test of the single pile meets the design requirements.(4)It is feasible to detect the integrity of super long perfusion piles in soft soil area by comparing the reflection wave method,and this reflection wave characteristic parameter can guide the subsequent integrity test of uninstalled acoustic tube pile.(5)The research results can provide reference for the study of the integrity of super-long perfusion piles detected by reflectance wave method in soft soil areas such as railways and highways.