Roadbed, embankment, tower support and culvert stability problems on permafrost

The history of railway and highway construction in permafrost zones in Russia, the United States, Canada, and China spans more than 110 years. Nonetheless, no railway track or highway has yet been built in such area that is impervious to deformation caused by subsidence resulting from the thawing of ice-rich subgrade soils. This paper presents data on the roadbed states of the Trans- baikalian and the Baikal-Amur Railways as well as the Russian ＂AMUR＂ Chita-Khabarovsk Highway. It also discusses the feasi- bility of roadbed stability maintenance using methods based on the reduction of the mean annual ground temperature and roadbed preservation in a permafrost state by means of the natural cooling and heating factors ratio regulation resulting in a reduction of the heat generation in the roadbed and the adjoining area accompanied by an increase of heat consumption with help of the sun-precipitation protective sheds （awnings）, rock covers, dolomite powder （reflective paint）, cooling tube and thermosyphons as well as tower supports and corrugated pipe culverts stability.

Effects of anti-pull ties on the bearing behaviors of shallow tunnel-type anchorages in soft rock

Tunnel-type anchorages(TTAs)installed in human gathering areas are characterized by a shallow burial depth,and in many instances,they utilize soft rock as the bearing stratum.However,the stability control measures and the principle of shallow TTAs in soft rock have not been fully studied.Hence,a structure suitable for improving the stability of shallow TTAs in soft rock strata,named the anti-pull tie(APT),was added to the floor of the back face.Physical tests and numerical models were established to study the influence of the APT on the load transfer of TTAs,the mechanical response of the surrounding rock,the stress distribution of the interface,and the failure model.The mechanical characteristics of APTs were also studied.The results show that the ultimate bearing capacity of TTAs with an APT is increased by approximately 11.8%,as compared to the TTAs without an APT.Also,the bearing capacity of TTAs increases approximately linearly with increasing height,width,length,and quantity of APTs,and decreases approximately linearly with increasing distance from the back face and slope angle of the tie slope.The normal squeezing between the tie slope and the surrounding rock increases the shear resistance of the interface and expands the range of the surrounding rock participating in bearing sharing.Both tension and compression zones exist in the APT during loading.The tension zone extends from the tie toe to the tie bottom along the tie slope.The range of the tie body tension zone constantly expands to the deep part of the APT with an increasing load.The peak tensile stress value is located at the tie toe.The distribution of compressive stress in the tie body is the largest at the tie top,followed by the tie slope,and then the tie bottom.

A Stable and Energy-Efficient Routing Algorithm Based on Learning Automata Theory for MANET

The mobile Ad Hoc network(MANET)is a self-organizing and self-configuring wireless network,consisting of a set of mobile nodes.The design of efficient routing protocols for MANET has always been an active area of research.In existing routing algorithms,however,the current work does not scale well enough to ensure route stability when the mobility and distribution of nodes vary with time.In addition,each node in MANET has only limited initial energy,so energy conservation and balance must be taken into account.An efficient routing algorithm should not only be stable but also energy saving and balanced,within the dynamic network environment.To address the above problems,we propose a stable and energy-efficient routing algorithm,based on learning automata(LA)theory for MANET.First,we construct a new node stability measurement model and define an effective energy ratio function.On that basis,we give the node a weighted value,which is used as the iteration parameter for LA.Next,we construct an LA theory-based feedback mechanism for the MANET environment to optimize the selection of available routes and to prove the convergence of our algorithm.The experiments show that our proposed LA-based routing algorithm for MANET achieved the best performance in route survival time,energy consumption,energy balance,and acceptable per-formance in end-to-end delay and packet delivery ratio.