Study On The Quality Test System Of Compactions Piles For Highway Subgrade In Loess Area

Compaction pile is often used to deal with the composite foundation for the collapsible loess foundation with low humidity and large thickness, which can be used to carry the upper load together, thus improving the bearing capacity of the foundation. Foundation treatment can meet the design requirements, on the quality of effective, rapid and accurate detection is very crucial link. However, highway industry currently to squeeze compaction pile composite foundation detection did not make clear quality evaluation methods and control measures, many engineering practice often referred to or part of the reference to the national standard, diverse practices, not unified, there a lot of problems. Therefore, in Qinghai province's new Kawaguchi to river highway to rely on, construction of compacted lime soil compaction pile test section study for on highway engineering of squeezed dense pile composite foundation detection system has extremely important practical value and theoretical significance. The overall research ideas, main research contents and results are as follows:1, Pile compaction coefficient and compaction coefficient of soil among piles have some certain relationships after theoretical analysis which depending on the essential objectives. But the existing process of quality test have some problems, such as disordered standard, different system benchmark, etc. In summary, foundation bearing force and pile soil collapsibility coefficient are the main testing standard of highway engineering in loess area, the compaction of the pile body, pile soil average squeeze compaction coefficient, pile soil between centroid of minimum compaction pile coefficient between connection index no longer were detected.2, The testing of single pile can only reflect the upper pile and soil intensity, it means that it will not represent the whole foundation intensity, so the soil parameters measured in the test section, in the software FLAC3 D were single pile and pile composite carrier loading test of three dimensional numerical simulation study, and analyze the effective influence depth. The simulation results show that the effective influence depth of the three pile composite load test is about three times of the diameter of the load plate, and the depth is close to the maximum treatment depth of the loess foundation which is required in the design code of highway subgrade 6m. In order to test the effect of pile and soil compaction and the strength state more comprehensively, it is proposed that the bearing capacity of compacted pile composite foundation can be increased by appropriately increasing the pile load test.3, At present, artificial excavation and sampling test were demanded by the testing standard the impact of this approach on construction quality and construction progress are larger, in order to solve the problem, discusses the static cone penetration test in situ testing method for the detection of pile soil wet subsidence feasibility. Research of inter pile soil static sounding and drilling sampling comparison test. The experimental results show that due to the influence of soil, moisture content and test operation, static cone penetration test values and the poor correlation between the coefficients of collapsibility, under the current technical conditions, difficult to collect with CPT method to detect the soil between piles of collapsibility.4, We improving the testing method by studying the new testing theory, working out a new artificial excavate instrument. In semi lossless found in the course of the development of testing equipment, earth inner diameter is too large, the soil column is not easy to maintain easily dropped. Test results show that the semi nondestructive sampling method can ensure the undisturbed soil samples and effectiveness, the sampling method and apparatus after further optimization, in inter pile soil wet collapse index detection has certain application prospect.5, We invent the testing procedure and rate by studying the theory of the testing standard and method. Proposing highway roadbed squeeze compaction pile composite foundation model quality detection system in loess area highway.