Abstract
Foundation can be subjected to additional load and constructed in soft soils; therefore, the settlement or foundation tilting is achieved. The most beneficial method to control the settlement and foundation tilting are to be used Micro-piles which have been considered is an effective and easy to reinforce the existing foundation, it also successfully adopted in many ground improvement techniques to safeguard structure from collapse. The paper aims to study the behavior of full-scale micro piles under compression in the filed with length of 20 m as end bearing with diameter of 88.9 mm. This study is focused on the observing the behavior of three micro-piles installed with different technique. The first is normal one without injection as pipe piles MP1, the second is pipe pile with grouted bulb MP2 only under the toe of micro-piles and inside grouting. The last one or third micro-pile MP3 is pipe pile with fully injection for both toe and around the pile length. Three loading tests in the field are carried out to show the load settlement response under axial compression and horizontal load to get the ultimate micro-pile capacity. The results showed that the fully injected micro-piles with grouting have a higher ultimate load capacity and minor settlement compared with other two cases. The ultimate load capacities for fully grouted micro-piles and only with grouted bulb are found to be 13 and 8 times of ultimate capacity of pipe micro-piles without grouted bulb at the toe respectively. Also, it is found that the ultimate horizontal load capacity of Mp3 is found to be 27 ton while it is recorded as 3 and 4 ton for MP1 and MP3 respectively at horizontal displacement of 0.2 micro-pile diameter.
Highlights
In current years, the use of micro-piles has grown to be more and more extensive all over the world because of it is considered as easier installation for existing foundation with acceptable rates of daily creation and their extensive range of ground improvement applications
The tested micro piles to reinforce model raft for various situation, for example soil type, pile depth, and inclination angle are investigated in the laboratory [10], [11] the experimental results showed that if the micro-pile depth is adequately longer than the depth of foundation failure surface, the micro-piles will resist the ground deformation and extend the failure zone
For MP2 end bearing case due to grouted bulb produced at the base which has a diameter (Dg of 4 to 6 times of pile diameter (D), which is considered for the tested micro-pile around 55 cm as stated by
Summary
The use of micro-piles has grown to be more and more extensive all over the world because of it is considered as easier installation for existing foundation with acceptable rates of daily creation and their extensive range of ground improvement applications. There are many applications of adopting micro-piles in the field of ground improvement technology especially for reinforcing existing structure [2] and [3]. Micro-piles are considered as an excellent solution for seismic retrofitting of foundation due to their obtained frictional resistance structural grouting around piles and surrounding soils. The existence of such pressure grouting within the micro-piles can significantly provide improved load transfer system. The application of using such technique for strengthening existing raft foundation can be successfully used in a wide range This technique is considered to be significant in resisting vertical and lateral capacity that can be investigated and confirmed in the current research. The behaviour of mentioned micropiles under both vertical and tension has been investigated with details to confirm the effectiveness of such technology
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