Research On Self-expanding Expansion Anchoring Technology Of Soil Layer

In this paper,the long-term stability of expansive cement slurry under different soil stiffness in immersion environment,the compressive strength of expansive cement slurry and the anchor pull-out test of self-expansive body anchoring technology of soil layer are discussed in this paper.The visualization of anchor solid expansion mechanism of soil layer self-expansion extender anchoring technology and its field application are studied.The main conclusions are as follows:1)Experimental study on Anchor drawing of self-expandable expansion Anchor Technology in soil layerThe steel pipe with different wall thickness is used to simulate the soil confined environment with different consolidation degrees,and the long-term stability test of the expansive cement slurry under long-term immersion environment is carried out.The analysis shows that the expansion compressive cement has the largest difference between the expansion compressive stress before immersion and long-term immersion.3.10%;the maximum difference of the expansion anchor solidity(CT value)is only 3.85%,which indicates that the expanded cement slurry can remain stable for a long time in the long-term immersion environment.Independently research and develop a device for measuring the compressive strength of expanded anchors under confined conditions,and carry out the compressive strength test of expansion anchors under different curing time.The results show that the expansion agent can effectively improve the compressive strength of the expanded anchor.And the compressive strength of the expanded anchor is almost completely formed in about 21d,which shortens the curing time of the slurry and saves the construction period.2)Experimental study on Anchor drawing of self-expandable expansion Anchor Technology in soil layer? Study on drawing of shallow in-situ soil anchorsThe ultimate pullout resistance of the anchor of the expanded cement slurry anchor is greatly improved compared with the plain cement slurry,and the maximum is 3.45 times that of the plain cement slurry;Under the same expansion agent content,the ultimate pullout force of the bolt is positively correlated with the anchorage length,indicating that the side friction resistance caused by the expansion pressure is the key factor to improve the ultimate pullout resistance of the bolt.?Experimental study on bolt pullout under different overburden pressure and water-rich environment of remolded so1lDevelop a bolt puller that simulates different overburden pressures,and carry out the bolt pull-out test.The results show that the ultimate pullout force of the bolt is proportional to the applied overburden pressure of the soil,and the same Under the top-loading pressure loading level,the ultimate pull-out strength of the bolt increases with the increase of the expansion agent content,and the maximum value is 336%,indicating that the anchoring technology has a significant effect on improving the bolt pull-out resistance.The open-tube steel pipe is used as the carrier to carry out the drawing test of the steel pipe in the water-rich environment.The results show that the ultimate pullout force of the steel pipe is positively correlated with the diameter of the steel pipe and the content of the expansion agent,and the expansion agent improves the ultimate pullout resistance of the steel pipe.The amplitude is larger than the diameter of the steel pipe to increase the ultimate pullout resistance of the steel pipe,which indicates that the anchoring technology improves the ultimate pullout resistance of the steel pipe in the water-rich environment,and can adapt to the complex environment in practical engineering and has a wide application field.3)Study on Technical Mechanical parameters of self-expandable body Anchor in soil layerThe three factors of the lateral expansion pressure of the anchor,?1 the correction coefficient of the anchor diameter,?2 the correction coefficient of the anchor and ?3 the lateral expansion deformation of the soil are proposed,and use Matlab to obtain the linear variation law of ??? values with the content of expansive agent.The bolt shear stress suitable for self-expanding expanded soil anchor technology is established,and the influence coefficient of soil compactness is proposed.Finally,the ultimate pullout force calculation formula of the anchoring technology is obtained.4)Visualization study on Anchor solid expansion Mechanism of soil layer self-expansive Expander Anchor TechnologyDevelop a visualization device for observing the expansion effect of expanded cement slurry.Using it to carry out tests and cooperate with CT scanning test,the results show that within the so1l tolerance range,the expansion anchor expansion range is proportional to the expansion agent content.Regularity,the relationship between radial transfer force e of expansive compressive stress in soil layer and circumferential compactness of soil layer(CT numbers)and its distance from expansive anchoring agentx and content of expansive agent A was established.The transfer rules of dilatational compressive stress from inside to outside is obtained.The expansion pressure in the anchor itself transfers from the center of the anchor to the outer layer of the anchor,and the expansion pressure in the soil transfers from the pore wall of the anchor hole to the outside of the soil layer,and the two are completely changed.The opposite transfer law provides a theoretical basis for the application of the anchoring technology in the actual anchoring,anchoring and anti-slide pile anchoring engineering,and is widely used in engineering.5)Field test application research of self-expanding and expanding soil anchor technology in the Three Gorges reservoir area,and verifying and perfecting the new soil with various technical means such as non-metallic acoustic wave test,pressure test,strain acquisition and endoscopic cave imaging.The anchor technology again shows that the main reasons for improving the ultimate pullout resistance of the bolt are:?the expansion pressure exists,?the expanding anchor effect exhibited by the expansion anchor,which at the same time determines the ultimate ultimate pullout force of the anchor.To sum up,the effect of self-expandable reinforcement anchoring technology on improving the pullout resistance of anchor rod is remarkable,and the prediction formula of ultimate pullout force of the anchoring technology is established,and the transfer law of expansion pressure in the anchor solid itself and in the soil layer is analyzed.The optimal design method of ultimate pullout force design parameters of anchor rod with different expansive agent content is put forward,which provides theoretical basis and technical support for the application of anchoring technology in anchoring engineering such as anchor rod,anchor cable and anti-slide pile.