Method for judging pile body uniformity of cement soil stirring pile

Abstract

The invention discloses a method for judging pile body uniformity of a cement soil stirring pile. The method comprises the steps of: (1) definition of a quality coefficient C1, an intensity coefficient C2 and a pile body uniformity coefficient M; and (2) judging method. The method for judging pile body uniformity of the cement soil stirring pile, disclosed by the invention, has the advantages that: the judging method is a quantitative index which comprehensively reflects a plurality of factors of pile formation uniformity of the cement soil stirring pile and can directly judge whether the stirring pile satisfies construction technical requirements; the mass coefficient and the intensity coefficient defined by the method can reflect clear physic meanings; a quantitative evaluation index which synthesizes various factors and is objective, impartial, convenient, good in operability and uniform in evaluation criterion is given for the first time to overcome randomness of judging a result through naked eyes manually in the specification; and according to the judging method, a test sample is directly adopted after an unconfined compressive strength test rather than adopting a test sample additionally so that a plenty of detection cost is saved.

Description

technical field [0001] The invention relates to the technical field of building pile foundations, in particular to a method for judging the uniformity of a cement-soil mixing pile body. Background technique [0002] The cement-soil mixing method is a new method suitable for reinforcing saturated soft cohesive soil foundations. It uses cement as a curing agent and uses a special mixing machine to forcefully mix the soft soil and cement slurry deep in the foundation. A series of physical and chemical reactions between the agent and the soft soil harden the soft soil into a cement-reinforced soil with integrity, water stability and a certain strength, thereby improving the foundation strength and increasing the deformation modulus. [0003] The current "Building Foundation Treatment Technical Specifications" (JGJ79-2002, J220-2002) stipulates that the construction quality inspection of cement-soil mixing piles can adopt the following methods: [0004] ① After 7 days of pile fo...

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Problems solved by technology

[0007] The integrity of the pile body has been tested by using the method recommended in the code and the manual, but the results are not satisfactory, mainly in the following aspects: ① The treatment depth of cement-soil mixing piles for soft soil foundation is generally within 20m, and different soil properties within the treatment depth Stirrability is not the same. Only the result of excavation pile head judgment cannot fully reflect the overall situation of the pile body, and there is no specific index judgment, and the expression by visual inspection is relatively random, and it is difficult to objectively reflect the real situation of the pile body. Uniformity; ②In silt soft soil, within 3 days of pile formation, light dynamic penetration (N10) can be used to check the uniformity of each meter of pile body, which is not feasible; when mixing piles in silt soft soil, the amount of cement is average Between 10% and 16%, the cement solidification speed is very slow after in-situ pile formation, because the original soil structure has been destroyed during pile formation, and the cement soil in the 3d internal pile has not solidified to a certain extent, so light dynamic penetration testing is used The test results of (N10) have no obvious changes from those before pile formation, and even the number of hits is smaller than that of the soil layer before pile formation

Therefore, there is no suitable method for judging and evaluating the uniformity of cement mixing in cement-soil mixing piles so far.

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