复活堆积体滑坡治理中大口径抗滑桩监测与滑坡推力分析

Monitoring of large-diameter anti-slide piles and analysis of landslide thrust in resuscitated accumulation landslides

为研究复活堆积体滑坡治理中大口径抗滑桩的承载特性和滑坡推力,以舟曲江顶崖H1滑坡治理工程为依托,在3根大口径抗滑桩迎滑面和背滑面的中部与角部分别布置钢筋应力计、混凝土应变计,在桩身迎滑面护壁外侧布置土压力盒,对其长期监测结果进行深入分析。结果发现:(1)大口径抗滑桩受力性能良好,抗滑桩迎滑面、背滑面桩身应力均存在多个局部极值点,复活堆积体滑坡治理中抗滑桩设计不宜直接采用现行规范计算;(2)大口径抗滑桩截面内沿宽度方向上的中部和角部钢筋应力不相等,迎滑面中部钢筋所受最大拉应力可达角部钢筋应力的2.4倍,采用基于平截面假定的规范法计算桩身内力需要修正;(3)根据实测结果反算的桩身弯矩存在多个局部极值点,同时桩身存在多个剪力0点,表明复活堆积体滑坡存在多级滑面,后继该类滑坡治理应考虑主、次滑面位置;(4)由土压力盒监测滑坡推力分布形式与规范法不同,其合力值为规范法计算结果的1/3,由监测钢筋应力反演滑坡推力的合力值为规范法计算结果的1/2;(5)多滑面复活堆积体滑坡治理中大口径抗滑桩桩土相互作用复杂,采用规范法计算的桩身内力偏大。研究成果可为该类复活堆积体滑坡治理提供科学依据。

In order to study the bearing characteristics and landslide thrust of large-diameter anti-slide piles in the treatment of revived accumulation landslides,based on the Treatment Project of H1 landslide at the Jiangdingya of Zhouqu County,steel bar stress gauges and concrete strain gauges were respectively arranged at the middle and corners of the front and back sides to sliding surface of the three large-diameter anti-slide piles,and earth pressure cells facing the sliding surface are arranged outside the retaining walls of the anti-slide piles.In this way,the long-term monitoring results were analyzed.The results show that:(1) The large-diameter anti-slide piles present good mechanical properties and have many extreme stress points on the front and back sides to the sliding surface.The design of anti-slide piles in the treatment of revived accumulation landslides should not be directly calculated by the current way;(2) In the section of large diameter anti-slide piles,the stress of the steel bar in the middle and corner along the width direction is not equal.The maximum tensile stress on the steel bar in the middle part of the front side to sliding surface can reach 2.4 times of the stress on the steel bar in the corner.It is not suitable to adopt the method recommended by the current code directly in the design of anti-slide pile in the treatment of resurrected accumulation body landslide;(3) The pile bending moment calculated according to the measured results has several extreme points,and the shear force of the anti-slide pile has multiple zero points,which indicates that there are multiple sliding surfaces in the revived accumulation landslide.The positions of the primary and secondary sliding surfaces should be considered in the subsequent landslides treatment project;(4)The distribution form of landslide thrust monitored by the earth pressure box is different from that of the code,and the resultant value is 1/3 of that calculated by the code.The resultant value of landslide thrust retrieved from the monitoring steel stress is half of the calculated result of the method recommended by the design code;(5) The pile-soil interaction of large diameter anti-slide pile in landslide control of multi-stage surface revived accumulation body is complicated,and the internal force of pile body calculated by design code is too large.The research results can provide scientific basis for the landslide treatment of this kind of revived accumulation body.