Study On The Method For Determining The Mechanical Parameters Of Sand Pebble

Sandy pebble stratum is a typical unstable rock stratum in Chengdu city.Its mechanical properties are very different from other rock and soil.The strength of single pebble is high,the ability of self stability is poor,the cohesion is small,and the grain size is quite different. With high buildings and subway were built in succession,in deep foundation pit branch supporting design,of sand and gravel mechanics parameters is also has great difficulty,because so far,there is no a good method to determine the mechanical parameters of sand gravel.Empirical method,laboratory test,field test and numerical inversion analysis are the main methods to determine the mechanical parameters of sand and gravel.A mechanical parameter method is proposed to determine the degree of compaction degree and particle size of sand and gravel.The feasibility and rationality of the method are verified by laboratory experiment and field two examples.It mainly includes the following parts:(1) Based on the theory of particle flow,a new method for determining the mechanical parameters of sand and gravel with different compaction degree and different particle size is presented.(2) In the laboratory,the calibration test of sand and gravel meso parameters is completed,and the single axial compression test and large direct shear test.(3) Through the sensitivity analysis of the parameters of sand and gravel and sand and gravel chamber test,sand pebble micro parameters ks,kn,kn/ks and fric were determined.(4) With the new method is completed to determine the macro mechanical parameters of E,μ,φ sand and gravel with different compaction degrees and different particle sizes under the conditions of the.But there is a hypothetical condition that the parameters of sand and gravel do not change with the change of the density of sand and gravel and the size of different particles.(5) The feasibility and rationality of the new method of mechanical parameters of different compaction degree and particle size of sand and gravel are determined by the indoor and field two examples.After the analysis of these two examples,the new method is feasible and reasonable.