山区铁路抗滑桩完整性检测及断桩原因分析

研究目的:采用声波透视法、反射波法对砂岩、泥岩地层中施工的抗滑桩进行完整性检测,发现有一些桩约在同一标高出现明显声速低、反射波曲线出多次反射呈断桩特征,经开挖验证以及钻探取芯证实是断桩,而此断桩是什么原因引起,如何预防,需进行研究。研究结论:引起抗滑桩断裂主要原因是抗滑桩施工时采用人工同时开挖,并用少量炸药爆破进行,因抗滑桩断桩处的岩层是薄层呈土状软弱层,其节理面倾向与山体斜坡倾向基本一致,使得先挖孔的最深地段容易引发局部山体不稳定而滑动。因此,为避免抗滑桩断裂,应在抗滑桩施工时,采用小直径(φ=20 cm)钻芯多次成孔逐渐形成矩形桩孔;同时采取间隔抗滑桩施工,待第一批间隔施工的抗滑桩混凝土灌注时间达28 d后,再施工第二批间隔抗滑桩。

Integrity Testing of Anti - slide Pile for Railway in Mountain Area and Analysis of Causes for Pile Fracture

Research purposes: The acoustic wave scenography or reflection wave method was used to test the integrity of the anti-slide pile in sandstone or mudstone stratum.The test results showed the pile-fracture characteristics of the apparent low sound speed and repeated reflection of the reflected waves occurred to a number of piles in the same elevation.The verification of the excavation and core-drilling showed the piles were broken.So it was necessary to research the reasons for the the pile fracture and how to prevent the pile fracture. Research conclusions:The cause for the anti-slide pile fracture was the manual excavation and blasting when conducting the anti-slide pile to easily make some massifs in the deepest area where was the first to bore unstable and slide because the the places where the piles fractured were of the weak soft layers and their inclination of the fissure surfaces were basically with the that of the inclined slope of massif.Therefore,to avoid the anti-slide pile fracture in the construction,the small diameter(=20 cm) bore core would be used to form pore time and again and gradually form the rectangle pile pore,and at the same time the intervals anti-slide pile would be conducted.Namely,the second batch of the interval anti-slide pile would be conducted after 28 days that the concrete pouring to the first batch of the interval anti-slide pile was finished.