Method for detecting secondary consolidation coefficient of soft soil indoors and measuring device using same

Abstract

The invention relates to a method for detecting secondary consolidation coefficient of soft soil indoors. The method comprises the following steps: (1) placing a vessel on a base, allowing a fulcrum to be contacted with the upper cover of the vessel, and allowing a contact of a sensor to be elastically contacted with the fulcrum; (2) introducing air to a piston to jack the vessel and the sensor, lowering the contact in a jacking process to ensure that the contact is constantly contacted with the fulcrum; (3) sending lowered distance delta h of the contact to a control system after the distance is acquired by the sensor, and calculating the void ratio e by a formula, wherein e0 is the natural void ratio of soil and constant, h0 is the height when a sample is in zero load; (4) constantly lowering the contact along with time extension, calculating the void ratio in real time by the control system, and finally generating a curve graph of a secondary consolidation coefficient (time logarithm-void ratio), wherein the curve completely comprises an upper curve section, a middle linear section and a lower linear section; and (5) calculating the slope of the lower linear section of the secondary consolidation curve, and calculating the secondary consolidation coefficient Ca. The method ensures that the whole curve is extended by increasing time-taking under each grade of load, and the secondary consolidation segment can more clearly reflect the law that soil body changes along with time extension. The final settlement of a building can be calculated according to curve tendency, namely the relationship of basic settlement and time, by combining the service life of the building, the engineering stability range can be calculated so as to ensure engineering safety.

Description

Indoor method for determining the secondary consolidation coefficient of soft soil and the measuring device used in the method technical field The invention relates to geotechnical engineering investigation and test, in particular to a method for indoor determination of secondary consolidation coefficient of soft soil. The invention also relates to geotechnical engineering exploration test equipment, in particular to a measuring device for indoor determination of the secondary consolidation coefficient of soft soil. Background technique The final settlement of soft soil foundation consists of instantaneous settlement, consolidation settlement and secondary consolidation settlement. The secondary consolidation settlement of the soil refers to the slow deformation of the soil skeleton that continues to occur over time when the effective stress remains unchanged after the primary consolidation process (excess static pore water pressure dissipation process) of the soil sample...

AI Technical Summary

Problems solved by technology

At present, there is a lack of effective means and related test equipment for testing the sub-consolidation coefficient in China, which is manifested in: 1) There is no testing method and requirement for the sub-consolidation coefficient in the national standard "Soil Engineering Test Method Standard" and other places and industry specifications; 2) according to The physical significance of the secondary consolidation coefficient and the test of the conventional 24-hour stability method show that the curve of the secondary consolidation coefficient under some loads only reflects the main consolidation section at the front end, and the secondary consolidation section at the rear end does not appear; There are low test accuracy and output lag phenomenon in the test with the instrument test equipment; 4) The manual loading produces an instantaneous impact force on the sample; 5) The loading is not synchronized with the timing and manual recording data; 6) The data collection is cumbersome and the test cycle long

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