Research On Molding Process And Field Testing Technology Of Silt Subgrade

Silt soil is characterized by low natural moisture content, little plastic and water distribution quickly. The compacted soil is loose and does not harden. Roller compaction confectioning is not easy. With the water evaporation loss of the forming roadbed and in the subsequent repeated action of the construction truck, the roadbed produces deep rutting and the construction site was extremely disorderly. At present, there are not effective control measures, it leads to regular degree of compaction and rebound deflection detection can not effectively be used, so using silt soil for filling roadbed faces many technical problems.To solve the above-mentioned problems of silt sand roadbed construction and testing, the paper selected three representative samples in the Nen River Valley and did physical, hydraulic, compaction and shear strength experiments in the laboratory, it analyzed and summarized the engineering properties of silt sand; and we paved for four compacted thickness of experiments road with three different soil samples, it summed up the reasonable compacted thickness of silt soil roadbed, molding process, and rolling machines; On this basis, By comparing the correlation analysis among the traditional sand cone method, the filling density of the scene detector method, Benkelman beam deflection and portable falling weight deflector meter, it studies on the feasibility of the new detection technology application in the compacting quality test of silt sand roadbed. The results showed that the test results of liquid limit and plastic limit are not appropriate for evaluating soil properties, The magnitude of plastic index Ip can't correctly reflect its viscosity magnitude too; For silt soil, we should name it that the proportion of powder grain and sticky grain in coarse-grained soils group which determine using the method of desimeter method; the content of fine-grained group and sticky grain in silt soil can improve its maximum dry density and optimum water content, and the content of fine-grained group is more, the compaction performance is better. the compaction quality with vibratory roller of small tonnage is difficult to meet the requirements and economically irrational, but the vibratory roller of large tonnage, such as the vibratory roller of 20 tonnage is proposed in the silt sand filling roadbed. Construction. Relying on increasing the compaction thickness to reduce moisture loss of silt sand roadbed is feasible, and its compaction quality can meet the requirements; On silty soil as roadbed stuffing, water ratio is essential, the water content of subgrade construction should be detected, usually to the surface from the outside watering is not loose, no liquefaction is the best, and in the rolling molding, the closure of the traffic is very important, in order to shape a close a period, as much as possible to reduce vehicular traffic on the destruction of silty roadbed. By using density of the scene detector method to test compaction, handhold falling weight deflectormeter to detect rebound deflection and modulus of resilience during the silt sand roadbed construction, can meet the detecting demand for engineering quality and improve the detection efficiency.