Classification of Rock Mass Structure and Its Scale Effect

( Shengwen Qi ),( Songfeng Guo ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

As known that many kinds of rock mass classification systems have been presented to classify the rock mass quality, e.g., RMR system, Q system, GSI system. However, only a few of references consider the effect of rock mass structure in the rock mass classification. It is always a difficult task to describe rock mass structure quantitatively. In this paper, a classification scheme for rock mass structure was presented based on Gu et al. (1979) after a thoroughly review. The classification considered the lithology, petrography as well as tectonics; meanwhile the attitude of the bedding plane is stressed in the classification, as a significant indicator for experienced tectonic intensity and also the rock mass stability. The classification divided the rock mass structures into five main types, i.e. magmatite or orthometamorphite structure, sedimentary or parametamorphite structure, tectonite structure, decomposed rock structure and loose structure. Each type contains some subtypes which are depicted in both a qualitative and quantitative way to ease the application. The scale effect of rock mass classification is then discussed considering the size of rock matrixes and discontinuities. The mechanical behaviors of each rock mass structure type are investigated with a number of field cases.

Engineering of a Bacillus subtilis Strain Deficient in Cellulase: Application in Degumming of Ramie

Qi Yang,Shengwen Duan,Lifeng Cheng,Xiangyuan Feng,Ke Zheng,Chunliang Xie,Zhiyuan Liu,Yuande Peng 한국섬유공학회 2019 Fibers and polymers Vol.20 No.1

Degumming is the most important step before ramie fibers are used in textile industry. Conventional chemical degumming technology with alkaline treatment at high temperature causes critical problems in environment. In addition to multiple degumming enzymes (e.g. pectinases and xylanases), Bacillus subtilis strain 168 can also produce cellulase which brings irreversible damage to ramie fibers. In this study, a strain deficient in cellulase was constructed by insertional inactivation of gene eglS to make it suitable for microbial degumming. Results showed that the cellulase activity was not detected in strain ΔeglS, after 25 h of incubation with strain ΔeglS, the weight loss of the ramie fibers was 20.20 %. Though the residual gum content of ramie fibers obtained in microbial degumming process was 19.67 %, microbial intervention followed by diluted alkaline solution treatment showed lower residual gum content (2.73 %) than chemical degumming (2.96 %). The single fiber breaking strength value of ramie fibers from bio-chemical degumming process reached 27.19 cN, which was the highest of three samples. Moreover, bio-chemical degumming process resulted in a 75 % decrease of alkali dosage as compared with chemical degumming process. This study provides a suggestion to genetically modify wild-type strain in order to protect ramie fibers from cellulase damage, and indicates a sustainable alternative for the traditional chemical degumming in the textile industry.

A Probabilistic Framework for Mapping Hazards of Coseimic Landslides

( Mingdong Zang ),( Shengwen Qi ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

Coseismic landslides have been responsible for destroyed buildings and tens of thousands of deaths. Recent years, coseismic landslides occur frequently, and researches on coseismic landslides have become a global hot spot. Occurrences of earthquakes are random and difficult to predict accurately. Therefore, before an earthquake occurred, predicting the spatial distribution of coseismic landslides is one of key scientific issues needing to be solved in earthquake preventions. We have collected all of the data sets needed to conduct a regional probabilistic hazard analysis of coseismic slope instability, including: (1) 1:500000-scale geological map of the region, (2) extensive data on engineering properties of the geological units from geological surveying and field investigation, (3) historical seismic data of PGA from 1900 to 2018, and (4) high-resolution digital elevation models of the topography from ASTER. All of these data sets are digitized and rasterized at 30m grid spacing using ArcGIS and combined in a dynamic slope model based on Newmark permanent-deformation analysis modified by Barton model. The coseismic landslide displacements are estimated in each grid cell from a probabilistic framework through calculating a seismic hazard level of 10% probability of exceedance in 50 years, and the coseismic landslide hazard map is then generated based on the classification of the coseismic landslide displacement. The map can be applied to predict the hazard zone of the region and provide a reference for making decisions regarding infrastructure development and pre-earthquake construction.

Load-Balanced One-hop Overlay Multipath Routing with Path Diversity

( Jianxin Liao ),( Shengwen Tian ),( Jingyu Wang ),( Tonghong Li ),( Qi Qi ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.2

Overlay routing has emerged as a promising approach to improve reliability and efficiency of the Internet. For one-hop overlay source routing, when a given primary path suffers from the link failure or performance degradation, the source can reroute the traffic to the destination via a strategically placed relay node. However, the over-heavy traffic passing through the same relay node may cause frequent package loss and delay jitter, which can degrade the throughput and utilization of the network. To overcome this problem, we propose a Load-Balanced One-hop Overlay Multipath Routing algorithm (LB-OOMR), in which the traffic is first split at the source edge nodes and then transmitted along multiple one-hop overlay paths. In order to determine an optimal split ratio for the traffic, we formulate the problem as a linear programming (LP) formulation, whose goal is to minimize the worse-case network congestion ratio. Since it is difficult to solve this LP problem in practical time, a heuristic algorithm is introduced to select the relay nodes for constructing the disjoint one-hop overlay paths, which greatly reduces the computational complexity of the LP algorithm. Simulations based on a real ISP network and a synthetic Internet topology show that our proposed algorithm can reduce the network congestion ratio dramatically, and achieve high-quality overlay routing service.

Loess Collapsibility and Microstructural Characteristics of Farmlands Created by “Gully Land Consolidation” on the Chinese Loess Plateau

( Lina Ma ),( Shengwen Qi ),( Songfeng Guo ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

In order to cope with land degradation and create new farmlands for cultivation, a gigantic project “Gully Land Consolidation” was launched on the Hill-Gully Region of Chinese Loess Plateau in 2011. However, as a kind of particular remolded loess, these newly-created and re-filled farmlands suffered more seriously collapsible deformation due to their original soil structure was changed and destroyed. In this study, the south gully region of Yanan were selected as the typical study areas which were conducted from 2013-2018. And we took undisturbed loess samples of two types, ones were the natural loess including Q2 and Q3 loess which were sampled from the beside hillslope, others were the re-filled loess sampled from the newly formed farmlands by reshaping valley. Moreover, a series of consolidated drained compression tests and routine soil tests were carried out both on natural loess (Q2 and Q3) and re-filled loess with different water contents and compactness by Triaxial Compression Apparatus for Unsaturated Soil. Thus, studying the changes of collapsible coefficients and collapsible deformation between natural loess and re-filled loess, and analyzing the effects of water contents and compactness on loess collapsibility. Meanwhile, this study also research on loess microstructural characteristics by conducting the scanning electron microscope (SEM) and micron CT tests. The quantitative relationship between loess microstructure and macroscopic collapsibility characteristics were described, and differences of microstructure and pore between natural loess and re-filled loess were analyzed.

Back-analysis by UDEC of the Failure Process of Wangjiayan Co-seismic Landslide during 2008.5.12 Wenchuan Earthquake.

( Yu Zou ),( Shengwen Qi ),( Songfeng Guo ),( Zhifa Zhan ),( Xiaolin Huang ),( Bowen Zheng ),( Ning Liang ),( Jiaguo Xia ),( Xingxing Li ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

Strong earthquakes such as the 2008 Wenchuan earthquake often induced numerous landslides, which resulted in a large number of casualties and property losses. Under a strong earthquake, a rock slope often produced a dynamic progressive failure. Understanding the process of the dynamic progressive failure of the rock slope is of great significance for the prediction and prevention of the co-seismic landslide. Generally, the numerical method is a feasible and economic alternative to solve this problem. However, previous studies presumed the failure surface and area in the numerical model, which cannot reproduce the dynamic progressive failure of the rock slope. In this paper, we applied the Universal Discrete Element method (UDEC) was adopted to quantitatively characterize the dynamic progressive failure process of the Wangjiayan co-seismic landslide triggered by 2008 Wenchan earthquake. Different from previous studies, there exists no presumed failure surface and area was was presumed in the UDEC model. The initiation, coalescence of the local fractures and the formation of the final failure surface were well simulated in a real-time way. Some key factors influencing the dynamic progressive failure of the rock slope were systematically explored. This study provided a new insight to understand the disaster-pregnant mechanism, evolution, and formation of the co-seismic landslide.

Study on the Relationship Between Earthquake-induced Landslide Distribution and Topography in Wenchuan Earthquake

( Xianglong Yao ),( Shengwen Qi ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

The existing research proves that, unlike rainfall-induced landslides, earthquake landslides occur mostly in the high position of the slope, and the development of earthquake landslides has an obvious relationship with the topography. A large number of landslides induced in the Wenchuan earthquake also showed a similar relationship. The landslides occurred in the near fault area were large in density and large in scale, while the landslides in the areas far from the faults occurred mostly at the heights of the slopes and the landslide development density and scale were relatively reduced small. In this paper, five strip-shaped areas extending to the upper disc of the fault were selected in the upper seismic fault (central fault) of the Wenchuan earthquake, and the landslide boundary (without the accumulation area) was carefully interpreted. The object of research is to study the relationship between earthquake landslide and terrain. The study found that the scale of the earthquake landslide is mainly controlled by the fault distance and terrain.