Research And Development Of The High-pressure Waterproof Auto-stabilized Loading Test Device For Deep Soil

With the rapid development of the high-speed railway construction, and especially as China has invested more and more in it, the construction of high-speed railway has entered a new development stage. By 2012, the total distance of China's high-speed railway has reached over 13,000 kilometers and this number is expected to reach over 16,000 kilometers by 2020. The constantly invested high-speed railway means that the transportation enterprise and scientific and technical level in China has ushered in a new age. The stability of the subgrade is a key factor in high-speed railway's construction, particular the settlement problem. Therefore, monitor towards the settlement problem of the subgrade has become an important issue during the railway's construction. This paper mainly focuses on the practical situation of 29# pier soil on Shanghai Yangtze River Bridge and carries out proper calculation towards its bearing capacity by combining various regulations and currently adopted theoretical approaches. Meanwhile, on the basis of contrasting the calculation results, the designing and developing a high-pressure waterproof auto-stabilized loading test device for deep soil is proved to be necessary. What's more, the design and simulation experiment towards this device are also carried out and several valuable conclusions has been made as follows:1. The calculation results got by different methods vary a lot and this problem cannot be tackled even if the “safety factor” or “deformation control” is considered. Therefore, given the basic conditions of the deep large open caisson of Shanghai Yangtze River Bridge, it's necessary to further carry out theoretical and experimental researches towards the bearing capacity of the deep large open caisson.2. In order to check out a series of key problems like the bearing capacity and deformability of the soil under 100 meters deep of Shanghai Yangtze River Bridge, a high-pressure waterproof auto-stabilized loading test device for deep soil is designed, which will provide reference value to the experimental researches towards the bearing capacity of deep soil both home and abroad. The creativity of the device lies in placing the oil pump and loading system above, which effectively improves the whole reliability of the testing system.3. Both the strength and rigidity of the device are proved to meet the conditions for testing the soil's bearing capacity under deep subgrade through finite element modelling and experimental verification. In addition, its leakproofness and reliability are also verified through the laboratory test of simulating the actual water pressure as well as various multiples of the actual water pressure. By calibrating the values output from earth pressure cell, oil pressure sensor and water pressure sensor which are all needed in the field test, the accuracy of the future test towards the soil's bearing capacity is guaranteed.4. By installing the high-pressure waterproof auto-stabilized loading test device for the deep soil on the spot, an initial installation scheme is designed, which guarantees the smooth operation of the future spot experimental tests.