Foundation coefficient K30 test method of railroad bed for fine-grained soil construction

Abstract

The invention discloses a foundation coefficient K30 test method of railroad bed for fine-grained soil construction. Steps of the foundation coefficient K30 test method of the railroad bed for the fine-grained soil construction are that a testing surface of an area is level. A foundation coefficient tester is placed. A preload and a load of step-by-step in the test are loaded. A specific method loading the load of step-by-step in the test is that the foundation coefficient K30 of the railroad bed for the fine-grained soil construction is loaded step-by-step of the increment which is 0.04MPa of each level load. The finished load exerted by each level load is maintained for 4 minutes. Sinking quantity of the level load is recorded when the loading maintaining time of each level load meets the requirements. The test is completed when a test stopping condition of the foundation coefficient K30 test method is achieved. The foundation coefficient K30 test method of the railroad bed for the fine-grained soil construction is simple in operation, easy to implement, short in required test time, high in test efficiency, small in test error and capable of guaranteeing the true judgment of the railroad bed compaction quality.

Description

technical field [0001] The invention relates to a geotechnical test method, in particular to a foundation coefficient K for railway subgrade compaction quality detection 30 experiment method. Background technique [0002] Reasonably and efficiently inspecting the quality of subgrade compaction is of great significance to ensure the quality of subgrade filling and improve construction efficiency. Since the construction of the Datong-Qinhuangdao heavy-duty railway in 1985, the foundation coefficient K has been introduced. 30 The test method has been widely used in the subsequent railway engineering subgrade filling and compaction testing. Currently, K 30 The index has become one of the main technical indicators of railway subgrades, and has been officially included in the "Quality Inspection and Evaluation Standards for Railway Subgrade Engineering" (TB10414-2003), "Code for Design of Railway Subgrade" (TB10001-2005) and "Code for Design of High-speed Railways ( Trial Impl...

AI Technical Summary

Problems solved by technology

[0004] In the current "Railway Geotechnical Test Regulations" (TB10102-2010) specification, during the step-by-step loading test, the subsidence increment within 1min is not greater than 1% of the subsidence of the level of load as the control standard for applying the next level of load (ie 1% deformation stability control standard), the purpose of which is to make the subsidence under each level of load as close as possible to the final settlement, that is, to apply the next level of load after 99% of the deformation under the level of load has been completed, This relatively strict deformation stability control standard is theoretically reasonable for truly and accurately reflecting the deformation resistance of the soil structure, but as a test method for subgrade compaction quality inspection that needs to be carried out at the road construction site, there are the following unreasonable reasons Steps: 1) It is necessary to record the sinking increment at intervals of 1 min after each level of load is applied, and calculate whether the sinking increment and the percentage weighed under the loading test of this level meet the 1% deformation stability control standard, so that the test process Complicated operation; 2) "Code for Design of Railway Subgrade" (TB10001-2005) for the K of the subgrade structure filled with fine-grained soil 30 The value is required to be 80-90MPa / m, and the test settlement deformation is limited to 1.25mm and the load increment of each level of load is 0.04MPa. Generally, three levels of load need to be applied, and the average subsidence under each level of load is about 0.4~ 0.5mm, its 1% deformation increment is about 0.004mm ~ 0.005mm, the deformation increment within 1min exceeds the test accuracy of the dial indicator (0.01mm), it is necessary to estimate the reading of the dial indicator to determine whether it meets 1% Deformation stability control requirements, due to the influence of human subjective factors, resulting in experimental errors

3) Fine K 30 Experimental research shows that, in strict accordance with the loading control method of the current code, the subgrade structure filled with fine-grained soil generally requires only 3 levels of load to achieve a subsidence of 1.25 mm, but the test is terminated according to the requirements of the current code The load series is not less than 5 levels, and the load holding time to reach the 1% deformation stability standard under each level of load is about 10 minutes, and the total time of load holding is about 50 minutes. The required test time is longer and the test efficiency is higher. Low, during construction, it is necessary to wait for the completion of the inspection test and the inspection indicators to be qualified before the subsequent subgrade filling can be carried out. The waiting time for shutdown is long, which seriously affects the progress of the project

Images