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当前,在一些高层民用建筑和大型构筑物基础中,以微风化岩作桩端支承的大直径支承灌注桩,已经得到广泛采用。但是,由于这类桩的原位试验少,因此在其承载特性及承载力的确定方法上,尚存在一些需要深入研究的问题。对这类支承桩,目前人们仍然袭用摩擦桩的一套确定承载力的方法,即依据现场试桩得到的P—S(荷载-沉降)关系,寻求所谓屈服荷载和极限荷载,然后再除以相应的安全系数,取两者中的较小者作为单桩设计承载力。这种方法对支承桩来说是不适用的。原因是难于或者根本找不到确切的屈服荷载点;或者由于试验加荷吨位受到桩身强度和设备条件限制,很难加压至支承岩破坏,因此从支承基岩破坏角度也得不到确切
At present, in some high-rise civil buildings and large-scale structural foundations, large-diameter supporting cast-in-place piles with micro-weathered rocks as pile-end supports have been widely adopted. However, due to the small number of in-situ tests of such piles, there are still some problems that need to be further studied in terms of their bearing characteristics and bearing capacity determination methods. For this kind of support pile, people still use a set of friction piles to determine the bearing capacity, that is, according to the P-S (load-settlement) relationship obtained from the on-site test piles, seek the so-called yield load and ultimate load, and then divide by The corresponding safety factor, whichever is smaller, is used as the design bearing capacity of the single pile. This method is not suitable for supporting piles. The reason is that it is difficult or impossible to find the exact yield point; or because the experimental loading tonnage is limited by the pile strength and equipment conditions, it is difficult to pressurize the support rock, so the exact point of failure from the support base rock is not