Method for testing pile shaft stress of static pressure high-strength pre-stressed concrete pipe pile

Abstract

The invention belongs to the technical field of building construction stress testing and relates to a method for testing the pile shaft stress of a static pressure high-strength pre-stressed concrete pipe pile. When tensile force or pressure is received by a fiber Bragg grating sensor, the optical fiber grating period is changed due to the extension or the compression of the sensor, and therefore the effective refraction rate of the FBG sensor is changed. According to the axial strain of one section of the high-strength pre-stressed concrete pipe pile, the pile shaft stress of the static pressure high-strength pre-stressed concrete pipe pile is obtained, and therefore the axial force of a pile shaft, the side friction and the pile tip resistance are obtained. The method for testing the pile shaft stress of the static pressure high-strength pre-stressed concrete pipe pile is simple, convenient to operate, high in measuring accuracy, high in sensitivity, strong in electromagnetic field interference resistance, high in rate of survival, and capable of achieving quasi-distributed and automatic monitoring easier compared with a method of a traditional force testing element.

Description

Technical field: [0001] The invention belongs to the technical field of building construction stress testing, and relates to a prefabricated pile body stress testing process that adopts a static pressure method in foundation and foundation engineering, and particularly relates to a static pressure high-strength prestressed concrete pipe pile body stress testing method. Background technique: [0002] Concrete precast piles, especially high-strength prestressed concrete (PHC) pipe piles, have the advantages of high bearing capacity, factory production, strong and durable, fast construction speed, can effectively save construction materials and engineering costs, etc. The static pile method construction is noiseless, The vibration is small and the impact on the surrounding environment is small. It is suitable for construction in urban areas, areas with precision equipment and other areas with high requirements for the construction environment. Compared with the hammer method construc...

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Problems solved by technology

[0002] Concrete prefabricated piles, especially high-strength prestressed concrete (PHC) pipe piles, have the advantages of high bearing capacity, factory production, firmness and durability, fast construction speed, and can effectively save building materials and engineering costs. The vibration is small and has little impact on the surrounding environment. It is suitable for construction in urban areas, areas with sophisticated equipment and other areas with high requirements for the construction environment. Compared with hammering construction, the quasi-static pile pressure can ensure that the piles body integrity; compared with the large amount of waste mud produced by bored pile construction, static pressure pile construction is more environmentally friendly and pollution-free; most of the separation of static pressure pile sinking resistance is to obtain pile end resistance and pile side resistance through force-measuring elements Friction resistance, the force measuring element is easily affected by the test environment, so improving the survival rate of the force measuring element is the key to the success of the field test. For PHC pipe piles, attaching resistive strain gauges on the outside of the pile body is easy to be affected by the friction of the soil around the pile. If the pile is damaged, if the strain gauge is pasted inside the pile, it is not easy to operate due to the small inner diameter of the pipe pile, and the pipe cavity is easy to enter water, which is greatly affected by environmental factors, the accuracy is reduced, and the reliability and survival rate are not high; And vibrating wire steel bar stress gauge is stable, but the production process temperature of pipe pile is high, high temperature strain gauge is required, the cost is high and the survival rate is low; high-strength prestressed concrete pipe pile is different from square pile, steel pipe pile and other pile types , its own production process and characteristics have objectively caused difficulties in testing, and the processes of steel tensioning, pre-cast concrete, high-speed centrifugal rotation and high-temperature curing during the production process have caused great inconvenience to the pre-embedded force-measuring elements of the pile. Due to the thinness and weakness of the optical fiber, the sensor and transmission optical fiber must be carefully protected. The key to the success of in-situ monitoring of optical fiber sensing lies in how to realize the buried positioning of the sensor and ensure its survival rate in the extensive construction environment on site.

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