抗滑桩滑坡推力及桩前抗力设计计算

滑坡具有发生频率高、灾害损失严重等特点,合理计算抗滑桩滑坡推力及桩前抗力对于滑坡治理具有重要意义。滑面抗剪强度参数c、φ的设计值是根据少数钻孔取样进行试验得到或根据经验取值,不能代表滑面的平均抗剪强度,导致滑坡稳定安全系数及相应的滑坡推力曲线计算结果与实际情况存在差别。单排抗滑桩设计计算时通常不考虑桩前抗力,双排或多排抗滑桩滑坡推力的分配尚无相关规定,造成了抗滑桩滑坡推力及桩前抗力设计计算不合理。通过理论分析、数值模拟和工程应用等手段对滑坡稳定性状态及相应的滑坡推力曲线、单排抗滑桩滑坡推力与桩前抗力计算、双排抗滑桩滑坡推力分配等进行研究。研究得出:滑坡体处于极限平衡状态的判定依据为滑坡末端条块剩余滑坡推力T_n=0和滑坡体天然边坡稳定系数K=1.0,两个条件需同时满足;单排抗滑桩滑坡推力及桩前抗力设计计算中,当滑坡天然稳定系数K≥1.0时,采用实际c、φ求得的设计滑坡推力与实际滑坡推力之差作为抗滑桩桩上的设计值能保证滑坡的稳定;当K1.0时,应采用实际c、φ求得的设计滑坡推力曲线与桩前剩余抗滑力之差作为抗滑桩设计值。提出的考虑桩前土体剩余下滑力的设计计算方法能使双排抗滑桩更合理地分配滑坡推力。研究成果对抗滑桩的设计计算具有一定参考价值。

Design calculation of landslide thrust and front resistance of anti-slide pile

The landslide is characterized by high frequency of occurrences and serious disaster losses，so it is of great significance to reasonably calculate the landslide thrust and pre-pile resistance of anti-slide pile for landslide control. The design values of the shear strength parameters c and φ of slip plane are obtained from a few boring samples or the relevant experiences，and then cannot represent the mean shear strength of slip plane，thus lead to the differences between the calculation results of both the safety coefficient and the corresponding thrust curve of landslide and the actual situations. The front resistance of pile is usually not considered during the design of the single row anti-slide pile，while no any relevant specifications on the distribution of the landslide thrust are there for the dual-row or multi-row anti-slide piles，which makes the design calculations of both the landslide thrust and the front resistance of the anti-slide pile unreasonable. By means of theoretical analysis，numerical simulation and engineering application，the landslide stability status and the corresponding landslide thrust curve，the calculations of the landslide thrust and the front resistance of the single-row anti-slide pile，the landslide thrust distribution of the dual-row anti-landslide pile are studied. The study result shows that the determination criteria for the landslide body in the limit equilibrium state are the residual landslide thrust at the landslide end block of Tn = 0 and the the the natural slope stability coefficient of K = 1. 0 and both the conditions are necessary to be simutaneously satisfied. In the calculations of the landslide thrust and the front resistance of the singlerow anti-slide pile，the stabilty of landslide can be guaranteed by the difference between the the designed landslide thrust obtained from the actual c and φ and the actual landslide thrust. When K ＜ 1. 0，the difference between the the designed landslide thrust obtained from the actual c and φ and the actual landslide thrust must be taken as the design values of the anti-slide pile. The calculation method considering the design of the pile front residual sliding force proposed herein can make the dual-row pile to more reasonably distribute the landslide thrust. This study result has certain referential value for the design calculation of the anti-slide pile.