A measuring method for layered compactness of loess subgrade based on hydraulic compaction

Abstract

Subgrade compactness is a key factor determining subgrade quality. However, defects exist in the traditional methods for subgrade compactness measurement. Based on the theoretical analysis of dynamic impact and vibration waves, the hydraulic compaction method was used to measure the layered compactness of loess subgrade in this paper. A full-scale test was then carried out to observe the variation of soil parameters after hydraulic compaction. The results show that the layered interface settlement (LIS) of subgrade has the characteristic of stage change bounded by 0.9 m of depth and 6–9 blow times respectively. The compaction effect is not obvious when the depth exceeds 1.2 m, and thus the improvement depth was introduced. The settlement curve has the characteristic of the Boltzmann function. The relationship between layered compacted compactness and LIS was obtained by the regression method. Finally, based on the theory of layered compaction, a measuring method for the layered compactness of loess subgrade based on hydraulic compaction was presented. The field application demonstrates that the results of the hydraulic compaction method correspond well with that of the sand-filling method.

Wave Propagation Characteristics and Compaction Status of Subgrade during Vibratory Compaction

“…Zhang, Z.P. et al proposed a method for measuring the degree of layered compaction of loess roadbed based on hydraulic compaction given the theory of layered compaction [ 24 ]. Liu, L. et al proposed a parameter adjustment strategy for the frequency and amplitude of the drum, based on the coupled nonlinear dynamic model of the vibration wheel [ 25 ].…”

Research on Intelligent Compaction Technology of Subgrade Based on Regression Analysis

“…Subgrade soil settlement beneath pavements is a major concern for engineers [1]. Compaction plays an important role in improving the strength of the subgrade and pavement [2], and in long-term engineering practice, a variety of compaction quality evaluation indexes have been formed at home and abroad, mainly including two categories of physical testing indexes represented by compaction degree and mechanical indexes represented by elastic modulus [3,4], although the testing methods and principles of these evaluation indexes are different, but most of them have low testing efficiency, poor representation, lagging results, and other disadvantages. With the continuous development of the engineering industry, there is an urgent need for a device that can test compaction with the vehicle, which can display the compaction test results in real time and guide the operator to operate reasonably.…”