摘要
研究目的：通过阀门式长螺旋机施工的CFG桩径0.5 m、桩长5.2 m、混凝土标号为C30,桩端置于中风化砂岩的CFG桩完整性检测,发现完整桩低应变反射波曲线中,各桩端反射波的反射振幅不同,其振幅的大小是否与桩端的嵌固程度有关,需进一步研究。研究结论：反射波的反射振幅与桩端的嵌固程度有关;以采用反射波的反射振幅与入射振幅之比的反射振幅系数TA,分析CFG桩端的嵌固程度和单桩极限承载力高低,即TA=0.1~0.2桩端嵌固良好、单桩极限承载力QU=1000~1200 kN;TA=0.2~0.5桩端嵌固较好、单桩极限承载力QU=8 00~1000 kN;TMA=0.5~0.86桩端嵌固较差、单桩极限承载力QU=400~800 kN;以及反射振幅系数TA大于1时桩端嵌固程度极差,反射振幅系数TA为负数时桩端嵌固程度很好;桩端嵌固良好的CFG桩其单桩极限承载力高,反之就低。为使桩端嵌固良好、使单桩极限承载力能提高,CFG桩施工应采用合瓣式长螺旋机施工。
Research purposes： From the test to the integrity of the 0.5m diameter and 5.2m long CFG pile that was constructed with the valve type long screw machine and made of C30 concrete with the pile end locating at medium weathered rock it was found in the low strain reflection wave curve of the integral pile that the reflection amplitudes of the reflection waves were different to the different pile ends.It is necessary to further study whether the reflection amplitude level is related to the embedment of the pile end or not.Research conclusions：The reflection amplitudes of reflection wave was related to the embedment of the pile end.By using the proportional reflection amplitude coefficient T between the reflection amplitudes of the reflection wave and the incident amplitude,the embedment of the CFG pile end and the ultimate bearing capacity of single pile were analyzed.When TA was equal to 0.1-0.2,the embedment of the pile end was good and the ultimate bearing capacity of the single pile was of 1 200-1 000 kN.When the TA was equal to 0.2-0.5,the embedment of the pile end was rather good and the ultimate bearing capacity of single pile was of 1 000-800 kN.When TA was equal to 0.5-0.86,the embedment of the pile end was rather poor and the ultimate bearing capacity of single pile was of 400-800 kN.When TA was more than 1,the embedment of the pile end was poor.When TA was negative number,the embedment of the pile end was excellent.In a word,the better the embedment is,the more load the single pile can bear,otherwise the single pile bears less load.CFG pile should be constructed with gamopetalous-type long screw machine to get a good embedment and enhance the bearing capacity of single pile.
出处
《铁道工程学报》
EI
北大核心
2010年第11期14-17,共4页
Journal of Railway Engineering Society
关键词
CFG桩
反射振幅系数
桩端嵌固
合瓣式
CFG pile
reflection amplitude coefficient
pile embedment
gamopetalous-type long screw machine
