Novel marine soil full-flow penetration sounding system and test method

Abstract

The invention discloses a novel marine soil full-flow penetration sounding system and a test method, and belongs to the field of civil engineering. An oval-cross-section probe with an axial length ratio of 0.4 is adopted to further reduce a test error caused by the probe resistance coefficient, and linear relationships between the probe resistance coefficient, a resistance coefficient error and the axial length ratio is given; fiber bragg gratings are arranged on the outer wall of a probe rod to replace a traditional pressure sensor, the resistance of the end part of the probe and the lateralfriction resistance are tested in the cyclic penetration process; an algorithm of soil body undrained shear strength is given theoretically by using a limit analysis method of soil plasticity mechanics based on a full-flow theory, and a corresponding algorithm is given by combining a geometric form ratio of the probe and the probe rod; and a hole pressure sensor is arranged at the oval probe to test changes of hole pressure in the penetration process. Compared with existing test technologies, measurement errors caused by the difficult control over the probe resistance coefficient is reduced, the test method of the undrained shear strength of marine soft soil is optimized, and the accurate measurement of the shearing strength of the marine soft soil can be realized.

Description

technical field [0001] The invention belongs to the field of civil engineering, and relates to a novel marine soil full-flow penetrating probe system and a testing method, in particular to a testing method using an optical fiber grating sensor as a measuring component. Background technique [0002] In recent years, marine development has continued to develop from nearshore shallow seas to offshore deep seas, which has put forward higher requirements for the design, construction and operation of marine engineering. The survey technology that is closely related to the construction and operation of marine engineering, especially the test and evaluation technology for the strength of marine soil, has important engineering significance. At present, there are two methods for surveying the strength of marine soft soils: on-site survey and indoor test. However, the survey results are often affected by the accuracy of the instrument and the sampling quality of soil samples, and the e...

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Problems solved by technology

For example, due to the relatively low shear strength of marine saturated soft soil, for static penetrative penetration tests, in the high-pressure seabed test environment, the incremental gradient of penetration resistance with depth is too low, which will reduce the test accuracy

For the T-bar static penetration test, the analytical solution is obtained based on the full-flow theory and the limit method of plastic mechanics. The test results are relatively accurate, but affected by the size effect of the T-bar probe, the surrounding soil will The body often cannot reach the full flow state, which will lead to an underestimation of the strength of the soft soil within several times the depth of the probe; the traditional circular cross-section probe used in T-bar static penetration, its resistance coefficient is greatly affected by the roughness of the probe surface, The uncertainty of the drag coefficient can cause nearly 13% of the test error under the extreme conditions of complete smoothness and complete roughness

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