A method of distributed optical fiber sensing foundation deformation and determining foundation failure form and bearing capacity
A technology of optical fiber sensing and foundation deformation, which is applied in basic structure engineering, on-site foundation soil survey, construction, etc., can solve the problems of unseen foundation failure form and bearing capacity, and achieve the effect of overcoming low efficiency
Active Publication Date: 2018-06-12
NANJING UNIV
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Problems solved by technology
In the current period, the application of distributed optical fiber sensing technology in geotechnical engineering structures such as slopes, tunnels, and dams is increasing, but there are no reports of using this technology to determine the failure mode and bearing capacity of the foundation at home and abroad.
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Embodiment 1
[0023] (1) For a clay foundation to be tested, a groove with a length of 5m, a width of 10cm, and a depth of 3m is opened with a groove opener. Lay a distributed strain sensing optical fiber with a diameter of 1.2mm along the groove at a distance of 3m from the ground; backfill 1m of soil and compact it, and continue laying the optical fiber; then backfill 1m of soil and compact it, and lay another section of optical fiber; backfill the soil to the surface and compacted. From top to bottom, the three layers of optical fibers are respectively marked as H1, H2, and H3. Using the method of coiling this section of fiber in a special perforated plastic box, a 1m-long redundant section of fiber is installed on each layer of fiber to play the dual role of precise positioning of the fiber and self-compensation of temperature.
[0024] (2) Connect the distributed strain sensing optical fiber to the BOTDA optical fiber interrogator. The BOTDA demodulator used in this embodiment is pro...
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The invention relates to a method for sensing foundation deformation and determining foundation destructional forms and bearing capacity by distributed optical fibers. The method comprises the following steps that the positions of different depths of a foundation are horizontally slotted, and distributed strain sensing optical fibers are embedded and filled with earth; a loading device is used for applying loads on a pressure bearing plate on the earth surface of the foundation in a staged mode; the strain values of the optical fibers under different loads are measured by optical fiber demodulating equipment; a strain cloud diagram of a soil body of the foundation is drawn through interpolations, and the destructional forms of the foundation are judged; and a load-feature point strain curve (namely a p-epsilon curve) is fitted by a hyperbolic function, and the limited load bearing capacity value of the soil body of the foundation is worked out. Different from a traditional method, the method adopts a distributed optical sensing technology to monitor deformation inside the foundation in high-precision, fully-automatic and distributed modes, and the destructional forms of the foundation and the bearing capacity of the soil body of the foundation can be judged visually and rapidly through a monitoring result.
Description
technical field [0001] The invention relates to the fields of engineering foundations and optical fiber sensing, in particular to a method for detecting foundation deformation with distributed optical fibers and determining the failure form and bearing capacity of the foundation. Background technique [0002] The failure forms of the foundation mainly include overall shear failure, local shear failure and punching shear failure: the characteristics of the overall shear failure of the foundation are that when the load reaches the limit load, the foundation sinks rapidly, the foundation soil on the side rises upward, and the foundation forms Continuous sliding surface; foundation with partial shear failure, the ground on both sides of the foundation is slightly raised, and the shear failure zone is only limited to a certain area inside the foundation, without forming a continuous sliding surface extending to the ground; foundation with punching shear failure, There is no conti...
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IPC IPC(8): E02D1/08
CPCE02D1/08E02D2600/10
Inventor 朱鸿鹄张诚成施斌李飞许星宇
Owner NANJING UNIV