Loess covers about one-tenth of the world’s land area. While it is often used as embankment fill, loess is not an ideal construction material due to its wet collapsible nature, as it may cause significant embankment settlement and other related problems. Although explosive compaction (EC) technology has been used for many years, the challenges in experimental testing and theoretical analysis hinder its wider application. This paper contributes to the development of a design construction scheme of EC technology for loess embankment improvement through an integrated approach that involves finite element modeling, small-scale experiments, full-scale simulation and field implementation. In this study, a reliable finite element model is developed and validated through a small-scale experiment. The model is developed based on the software ANSYS/LS-DYNA®14.5 and takes into account the coupling between different materials (including soil, explosives, air and pavement). Critical performance factors such as the volume of the explosion cavity, the density of the compacted soil and the soil pressure can be obtained directly from the model. The model is then extended to simulate full-scale embankments. A sensitivity study is conducted to establish the correlations between the design parameters and the abovementioned performance factors. The relationships served as design guidelines for the successful implementation of the EC technique in an embankment section on the Cheng-Chao highway in China. The results demonstrated the feasibility of the EC technique as a ground improvement method for loess embankments, and it illustrated the effectiveness of the numerical method as a tool in design.
Dome A,Antarctica,has been thought to be one of the best astronomical sites on the Earth for decades.Since it was first visited by astronomers in 2008,dozens of facilities for astronomical observation and site testing were deployed.Due to its special geographical location,the data and message exchange between Dome A and the domestic control center could only depend on Iridium.Because the link bandwidth of Iridium is extremely limited,the network traffic cost is quite expensive and the network is rather unstable,the commonly used data transfer tools,such as rsync and scp,are not suitable in this case.In this paper,we design and implement a data transfer tool called NBFTP(narrow bandwidth file transfer protocol)for the astronomical observation of Dome A.NBFTP uses a uniform interface to arrange all types of data and matches specific transmission schemes for different data types according to rules.Break-point resuming and extensibility functions are also implemented.Our experimental results show that NBFTP consumes 60%less network traffic than rsync when detecting the data pending to be transferred.When transferring small files of 1 KB,the network traffic consumption of NBFTP is 40%less than rsync.However,as the file size increases,the network traffic consumption of NBFTP tends to approach rsync,but it is still smaller than rsync. 相似文献
The dynamic forces of sea water and backfill soil acting on coastal embankments and the hydrodynamic forces on offshore breakwaters have been analyzed using a finite-difference scheme. A non-horizontal sea bottom is considered in the analysis. Both rigid and flexible embankments are included in the study. For a coastal embankment, the hydrodynamic pressure of sea water acting on the embankment face significantly increases as the slope of the sea bottom increases. On the other side of the embankment, the pore pressure and the interaction force between the soil and fluid will augment significantly when the backfill soil is compressed during earthquakes. When the sea-embankment-backfill soil interaction is included, the dynamic forces acting on a flexible embankment are much larger than those on a rigid one. The comparison of evaluating the sliding of a cassion in a case study of SPM by a conventional analysis and the present seismic analysis was made. The earthquake-induced dynamic pressures on both sides of the embankment (or breakwater) could be much larger than the force generated by the storm surge. The hydrodynamic (or seismic) analysis incorporating the effect of an earthquake should be included in the coastal embankment or offshore breakwater design, especially for the area with active earthquakes. 相似文献