深厚软土中水泥土长短桩复合地基承载特性试验

Bearing Characteristic Experiment of Cement-soil Long-short Pile Composite Foundation in Deep Soft Soil

通过水泥土长短桩复合地基承载特性试验,实测长桩、短桩和桩间土顶面应力,探讨了采用水泥土长短桩方法对深厚软土进行处理时,复合地基桩土应力比及其变化规律。研究表明:水泥土长短桩复合地基荷载试验曲线同单一桩型复合地基一样均为缓变型;长桩和短桩桩土应力比均表现为先增大,后减小,再趋于稳定的趋势,并在临界荷载前后,复合地基主次桩顺序发生变化。根据试验结果,得到了考虑荷载水平的水泥土长短桩复合地基承载力计算公式,且计算结果同实测结果十分接近。

The stresses of long piles, short piles and soil were measured by the tests in situ on the bearing characteristics of cement-soil long-short piles composite foundation in deep soft soils; pile-soil stress ratio of composite foundation with cement-soil long-short piles and its variation rule with the Load were studied in deep soils. The investigation indicates that the Load test curves of long-short piles composite ground are gradually variable shape with single-pile composite foundation. According to pile-soil stress ratio, it is found that stress ratio increases first and then decreases and finally tends to stability. It is revealed that the sequences of primary piles and secondary pile are changed after critical load. Based on the result of load test, a computational formula for bearing capacity characteristic value of cement-soil long-short piles composite foundation which thinks of load level is developed. The calculated bearing capacity characteristic value is very close to the result of load test.