Study On Bearing Capacity Of Deep Foundation Embedded Into Expansive Soft Rock

By reviewing on the study on bearing capacity of deep foundation embedded in expansive soft rock, in the paper deep plate loading test and skin-friction field test is had. Based on the test results, load transfer functions of pile-tip and pile-shaft for argillaceous rock-socketed pile is gained. Inverse analysis by the test result of an argillaceous rock-socketed pile, revised equation of carried proportions of pile top load between pile base resistance and pile shaft resistance for embedded in argillaceous rock pile is gained. The bearing behavior of embedded in argillaceous rock pile in Nanning is analyzed by equation of load transfer function.On the basis of analysis of bearing behavior soft-rock-socketed pile, the theories and methods of it's designation, working behavior of rock-socketed segment, etal, the paper proposes some await further research problems for embedded in argillaceous rock pile in Nanning.The paper analyses and generalizes the engineering characteristics of mudstone. The characteristics of Half-rock and Half-soil and expansion make mudstone's characters complicated; Analyzes and evaluates various prospecting means applied mudstone. Deep Plate-load test of mudstone are made in two engineering. The results show discrepancy in bearing capacity for mudstone of different lithology, influence of water on bearing capacity of mudstone. By the results influence of change in lithofacies on ascertainment of bearing capacity of mudstone in identical engineering is analyzed. The paper explores initial loading-unload-second loading experimental characteristics of mudstone. On the basis of plate-load test data measured on 79 mudstone spots in 15 projects, the characteristics of p~s curves of mudstone are described. The zoning of types is performed for p~s curves. The feather of bearing capacity for different lithology is studied, and dispersive character of mudstone in bearing capacity in Nanning is analyzed.On the aspect of skin-friction of soft rock, work mechanisms of skin-friction in rock-socketed segment could be described as sliding-dilating-shearing mechanism. Through test and experiment the formulae which are advanced by scholars from domestically andabroad determining skin resistance value of soft rock are listed. They are mainly the relations between skin resistance and N, or qu, or frc. The paper makes field test for skin-friction of argillaceous rock. Results show skin resistance value of argillaceous rock is rather great. Critical relative displacement corresponding with ultimate skin resistance value is approximately 3 mm. Field shear test result curves by loading again and again verifies the mechanism of sliding-dilating-shearing.In the paper, load transfer functions of pile shaft and pile tip for embedded in argillaceous rock pile are established based on field test on skin resistance force and deep plate load test for mudstone. The functions accord with power function. Through inverse analyzing based on test result of a pile, relation equation of bearing proportions of pile top load between pile base resistance and pile shaft resistance is revised by quoting revising coefficient A s and A b. The paper analyzed bearing behavior of embedded in argillaceous rock pile in Nanning by load transfer functions of pile shaft and pile tip. Some conclusions valuable are obtained in the paper. Four test piles from an engineering example are calculated with load transfer functions of pile shaft and pile tip. Comparison their calculation results with field test data, shows bearing capacity design value for rock- socketed pile in Nanning area exist optimizational possibility. In Nanning the engineers should pay great attention to accumulation of static test data of pile embedded in argillaceous rock.