关键词: 双向搅拌桩, 标准贯入试验, 无侧限抗压强度, 电阻率

Abstract: With the review of disadvantages of traditional deep mixing cement-soil column techniques in China, which have resulted in many engineering problems and doubts about the effectiveness of the deep mixing techniques, a new bidirectional deep mixing column technique developed by authors is introduced. Comparison tests between the new and traditional deep mixing column techniques have been conducted in a highway construction site for soft ground improvement. The test results show that the quality of the cement-soil column constructed with the new technique is much better than that with the traditional one. The results of standard penetration test (SPT) and unconfined compressive test indicate that bidirectional deep mixing columns are more homogeneous in both horizontal and vertical direction. The electrical resistivity measurement results of core samples also present that more homogeneous microstructure is formed in the bidirectional deep mixing column. It is concluded that the new deep mixing technique should be popularized for soft ground improvement.

Key words: bidirectional deep mixing column, standard penetration test, unconfined compressive strength, electrical resistivity.