旋喷搅拌桩加固含易液化粉土夹层软基的现场试验

依托含易液化粉土夹层软基加固实体工程,采用现场试验的方法研究了旋喷搅拌桩加固含易液化粉土夹层软基的适用性和加固效果;通过钻孔取芯和静载试验测量分析了旋喷搅拌桩在含易液化粉土夹层软基中的成桩质量和桩芯强度;监测了路堤荷载下旋喷搅拌桩加固含易液化粉土夹层软基典型断面的施工期间及工后的地表沉降、深层水平位移、桩体荷载分担比、...

Field test on soft ground with liquefiable silt interlayer reinforced by jet-grouted mixing piles

For the engineering projects involving the reinforcement of soft ground with liquefiable silt interlayer, the applicability and effect of reinforcement using jet-grouted mixing piles were investigated on-site. The pile-forming quality and core strength of jet-grouted mixing pile were measured and analyzed by investigating the core samples obtained by drilling and static loading test. The data pertaining to ground surface settlement, deep horizontal displacement, pile load sharing ratio, pile-soil stress ratio, and excess pore water pressure were monitored under embankment load at a typical section of the soft ground during and after reinforcement. The reinforcement effect and stress characteristic on soft ground with liquefiable silt interlayer reinforced by the jet-grouted mixing piles were analyzed. Analysis results show that jet-grouted mixing piles can be successfully driven into the soft ground with liquefiable silt interlayer. The unconfined compressive strength of the pile core reaches 2.5 MPa at 28 d, which is nearly twice as high as the value of the core of conventional mixing pile. Under the embankment load, the jet-grouted mixing piles can effectively reduce the foundation settlement and the deep horizontal displacement at the toe of the slope, and improve the embankment stability. The pile-soil differential settlement is relatively small, the pile-soil stress ratio is 5-10, and the pile load sharing ratio is less than 50% in the jet-grouted mixing pile reinforced foundation, demonstrating the advantageous characteristic of the composite foundation. Composite foundation is divided into flexible pile composite foundation and rigid pile composite foundation. The design methods of the two are very different. The jet-grouted mixing piles studied in this paper is suggested to be designed as flexible pile composite foundation. Therefore, the soft ground with liquefiable silt interlayer reinforced by the jet-grouted mixing piles demonstrates satisfactory effect and can be used in practical engineering. 2 tabs, 12 figs, 30 refs.