极限应力法计算复合桩基沉降

UTMOST STRESS METHOD USED TO CALCULATE SETTLEMENT OF COMPOSITE PILE FOUNDATION

修正应力法是计算复合桩基加固区沉降的方法之一,其最大缺点是桩土应力比n难以确定。复合桩基中刚性桩受力的实测统计数据表明:基础边、角部刚性桩极限承载力发挥度在90%以上,基础中部刚性桩极限承载力发挥度也在80%以上。据此提出假定刚性桩承载力发挥到接近其极限承载力,从而可方便地确定桩土应力比n,解决修正应力法的难题,故称该计算方法为极限应力法。另外,对该假定造成的误差进行研究,并与修正应力法的误差进行对比分析,得出结论:修正应力法不考虑桩对土的侧限作用使沉降计算结果偏大,而此假定计算结果偏小,从而使极限应力法比修正应力法的计算结果更接近实际。

Modified stress method is a way to calculate stabilized layer settlement of the composite pile foundation.The main fault of this method is that it is too difficult to determine the pile-soil stress ratio—n.The statistics of the rigid pile stress in the composite pile foundation show that the ultimate capacity of rigid piles is used for over 90% in the edge and the corner of the foundation and over 80% in the middle.Accordingly the supposed capacity of rigid pile is close to its ultimate capacity.Thus the pile-soil stress ratio can be identified easily.So the new method is called ultimate stress method.In addition,the error caused by the hypothesis is studied.And it is compared with the error caused by the modified stress method.Conclusions are drawn as the following:the settlement calculated by the modified stress method without considering piles adjacent to the soil is bigger than reality;but it is smaller by the new assumption.So the settlement calculated by the ultimate stress method is closer to reality.