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为了研究钉形搅拌桩复合地基的承载特性,通过现场复合地基荷载试验对比分析了钉形搅拌桩和常规搅拌桩复合地基的承载力与桩土应力比,以三维数值模拟分析了设计参数对钉形搅拌桩复合地基承载力的影响,并探讨了钉形搅拌桩复合地基承载力计算方法。现场试验结果表明:钉形搅拌桩在节省水泥用量和施工时间的同时,取得了比常规搅拌桩更高的复合地基承载力,显示出很好的加固效果和经济效益。数值模拟结果表明:钉形搅拌桩复合地基承载力随着扩大头高度增加或桩间距减小而增大,随扩大头直径或桩长先增大后不变,即从复合地基承载力角度存在最优扩大头直径和桩长。钉形搅拌桩单桩承载力包括了扩大头下部土体的贡献,故可以将钉形搅拌桩等效为直径为扩大头直径的常规截面搅拌桩,按照桩、土复合的方法进行复合地基承载力计算,计算实例表明该方法计算的钉形搅拌桩复合地基承载力与现场荷载试验的结果比较接近。
In order to study the bearing capacity of nail-shaped mixing pile composite foundation, the bearing capacity and pile-soil stress ratio of nail-shaped mixing pile and conventional mixing pile composite foundation were compared by field composite foundation load test. The three-dimensional numerical simulation analysis of the design parameters of the nail Shaped mixing pile composite foundation bearing capacity, and discusses the nail-shaped mixing pile composite foundation bearing capacity calculation method. The field test results show that the nail-shaped mixing piles have higher bearing capacity of composite foundation than the conventional mixing piles while saving the amount of cement and construction time, showing good reinforcement effect and economic benefits. The results of numerical simulation show that the bearing capacity of the spiked mixing pile composite foundation increases with the increase of head height or the decrease of the pile spacing, and increases with the increase of the head diameter or pile length, ie, from the point of bearing capacity of the composite foundation Optimal expansion of head diameter and pile length. As the bearing capacity of the single pile of the spiked mixing pile includes the contribution of the soil below the enlarged head, the spiked mixing pile can be equivalent to a conventional sectioned mixing pile with a diameter of expanding head, and the composite foundation is carried according to the method of composite pile and soil The calculation of force and calculation example show that the bearing capacity of the spiked mixing pile composite foundation calculated by this method is close to that of the field load test.