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既有建筑物增设地下空间时,需要采用桩基础支撑上部结构,才能开挖建筑物下的土体。随着桩周土体的减少,钢管桩的稳定性会相应降低。利用虚拟嵌固点法提出了桩入土深度部分处于嵌固、未嵌固和半嵌固三种状态下受压计算长度公式。在模型箱内利用杠杆加载的方式进行了钢管桩的受压稳定承载力试验,分析了不同直径、外露长度的钢管桩在改变入土深度过程中稳定性的变化规律,结果表明:随着桩入土深度的增加,桩的稳定系数趋近一定值,该深度即为临界入土深度;桩的临界入土深度与外露长度无关,但与桩的刚度有关,刚度较大的桩,其临界入土深度也相应增加。比较虚拟嵌固点法、试验和JTS 167-4—2012《港口工程桩基规范》中规定方法得到的稳定系数可知,规范方法计算值明显偏低,虚拟嵌固点法计算值与试验值比较接近。
Existing buildings additional underground space, the need to use pile foundation to support the superstructure in order to excavate the soil under the building. With the reduction of soil around the pile, the stability of the steel pipe pile will be reduced accordingly. By using the method of virtual embedding points, the formula for calculating the compressive strength under three kinds of embedment, un-embedment and semi-embedment is proposed. In the model box, the load-bearing capacity test of steel pipe piles under the load of lever was carried out. The stability of steel pipe piles with different diameters and exposed lengths was analyzed. The results show that with the increase of The pile penetration depth increases, the stability coefficient of the pile approaches a certain value, the depth is the critical penetration depth; the critical penetration depth of the pile has nothing to do with the exposed length, but with the stiffness of the pile, the stiffness of the pile, the critical penetration depth Also increased accordingly. Comparing the statics method calculated by the method of virtual embedding point method, test and the method given in JTS 167-4-2012 “Port Engineering Pile Code” shows that the calculated value is obviously lower than the value calculated by the virtual embedding method compared with the experimental value Close to