Numerical Simulation For Vertical Bearing Behavior Of Large Diameter Belled Pile In Soft Substratum

With the development of municipal engineering, large diameter belled piles are used more and more widely, but the study on vertical bearing mechanism of it is not enough for the practice. In quite a good deal of foundation engineering in soft soil region, there is a kind of geologic condition that a thin hard stratum lays between soft soils. Sometimes the thin hard stratum can support the pile, it will decrease the pier's length and the cost of foundation. So, quite high value has always been put on that if the thin hard stratum is suitable for supporting course or not.In order to analyze vertical bearing behavior of large diameter belled pile in soft substratum, three-dimensional non-linear finite-difference numeric models are established with finite-difference program, calculated and measured results are contrasted, and it proves that the calculation models and the chosen parameters are rational. Based on the previous manner, the effect of soil parameters such as thickness of supporting course, depth of embedded and pile dimension on vertical bearing behavior of large diameter belled pile in soft substratum are studied.It is found that the bearing capacity of large diameter belled pile will increase with the increment of thickness of supporting course, bearing capacity and proportion of bottom-resistance are affected more notably by supporting course thickness when the supporting course thickness is small. When the ratio of modulus of surrounding stratum and supporting course is 0.2 and the supporting course thickness is relatively small, the ultimate bearing capacity of belled pier with large diameter is affected notably by depth of embedded. With the same thickness of supporting course, the bearing capacity of belled pier with large diameter is affected notably by modulus of surrounding stratum. The greater the modulus of overlying stratum is, the greater the bearing capacity. The bearing capacity of belled pier with large diameter will increase with the increment of modulus of supporting course, and the bearing capacity is greater affected by modulus of substratum. The affection of vertical bearing behavior of belled pier with large diameter in soft substratum by pier dimension is similar to the no soft substratum. The results are instructional to practices.