Research And Design Of Foundation Coefficient K₃₀ Detection System

Quality of railway subgrade compaction determines the safety and reliabilityas well as comfort requirements of the train, foundation coefficientK30canreflect the railway subgrade strength and deformation, as a control index ofmechanical railway subgrade compaction, it has an important role in insuring theconstruction quality of railway subgrade. UniversalK30detection instrumentexisting now reveals some problems such as error detection, more subjectiveinterference factors and management inconvenience, aiming at solving theseproblems, this paper employs sensor technology and embedded technology in thedesign of foundation coefficientK30automatic detection system.The paper analyses the detection methods at home and abroad of foundationcoefficient indexK30, introduces the basic principle in-depth of theK30plateloading test and the calculation and correction ofK30, discusses the influencingfactors of the calculation results. To solve the existing problems and deficienciesofK30plate loading test and to realize the construction of intelligence andinformation, the paper introduces sensor technology and embedded technology todevelopK30testing instrument, and the specific design scheme is presented.This paper put forward that BP neural network can be used to fit loadsettlement curve. Railway engineering geotechnical test procedures"(TB10102-2004) requires of classification of loading plate in implementation of loading andunloading, the load intensity and settlement of foundation obtained are discretequantity, then the field test data were fitted by BP neural network and establishthe relationship between the settlement and load intensity, and obtain the loadintensity when the settlement is1.25mm, thus getK30value. The softwaresimulation of the field test data demonstrates the correctness of the theory.This paper has completed theK30automatic test system hardware design, including the CPU circuit, data acquisition circuit, filtering circuit, A/Dconversion circuit, temperature and humidity detection circuit, liquid crystaldisplay circuit, GPS/GPRS circuit and so on， and realized the function ofacquiring and storage of load and settlement data, judgment of subsidencestability, drawing the load-settlement curves and calculating the value ofK30,also can be connected to a PC to export data, as well as the wirelesscommunication function with supervision station. Through the study of theindoor test of the system, proves the rationality of the system design.The field experiment was conducted with different layers of subgradecompaction in the Zheng-Xu passenger dedicated line fifth supervision section atdifferent time and different locations. Testing process in line with "soil testprocedures Railway Engineering". By comparison and correlation analysis withthe detection results of universal tester proved that automatic detectioninstrumentK30can better reflect the compaction state of foundation with higherstability and reliability, and can replace general testing instrument with automaticdetection instrumentK30.