Journal of Civil and Environmental Engineering

Deep excavation adjacent to existing buildings with shallow foundations and/or old wall bearing buildings represents a big challenge to the geotechnical engineer. The restriction of the lateral movement of the soil underneath those building represents the primary objective for any excavation support system. The previous research resulted in many excavation support systems including; soldier pile walls, sheet pile walls, secant piles, tangent piles, diaphragm walls, etc. These techniques may be cost-effectively for large and important projects but they are not for small projects which represent the majority. The main objective of this research is to study the stability of excavation sides in medium, stiff and very stiff clay soils either with or without a minimum safe lateral horizontal distance to the adjacent building. A parametric study was carried out to determine the minimum horizontal distance, H, for selected excavation depths, de, ground water depth, dw, and surcharge stress (q) underneath the neighboring buildings. The research outcomes showed that a significant saving can be achieved by excavation in very stiff clay excavation to a relatively large depth up to 9 m without retaining system. While for stiff and medium clay soils, a horizontal distance should be left beside the neighbored buildings depending on the magnitude of the surcharge stress, q.

The urban rail transit tunnel has many forms, such as single hole single line, single hole double line, parallel and non - parallel, intersection and separation, etc., The modeling is more complicated, the existing 3D modeling method of simple tunnel cannot meet this complexity requirement. According to the actual situation of urban rail transit tunnel, the paper defines the data structure of tunnel modeling, and puts forward the three-dimensional coordinate calculation method of different tunnel forms. According to the actual situation of urban rail transit tunnel, the paper defines the data structure of tunnel modeling, puts forward three-dimensional coordinate calculation method of different tunnel form, and realizes the 3d rapid modeling of urban rail transit tunnel, which meets the multiple modeling requirements of the tunnel.

Rapid population growth in Dhaka has resulted in excess generation of solid waste. Present solid waste management authority of Dhaka City Corporation is struggling to manage this huge amount of waste properly as there is no framework on solid waste management. The purpose of this work is to identify the present waste generation per person (Kg/person/day) in a housing society of Dhaka city and possible resource recovery potential of solid waste of the area so that the correspondent authority can have a scope of finding a framework for effective management of solid waste. The survey was conducted in 100 households of Mirpur Defense Officers’ Housing Society, (DOHS) Dhaka. These households were classified into five groups according to monthly income ranging from 60,000 BDT to 160,000 BDT. The total population of the area was around 15,000. Average waste generation was found 0.74 Kg/person/ day. Around 11.10 tons of solid waste was generated per day and major fraction was food waste (on average 69.90%). About 226 Kilograms of solid waste can easily be achievable for using as compost component every day. Possible energy recovery from generated waste was equivalent to 3428.70 Kwh of electricity per day

Yet a careful study of dechlorination kinetics on polychlorinated biphenyls (PCBs) congeners in transformer oil has not been investigated. 29 PCBs congeners were identified in transformer oil. Two sets of experiments were developed to study the effect of starch stabilized iron nano particles (NPs) concentration and temperature on the dechlorination of total PCBs. The experiments initiated with special initial concentration and lasted for an hour. The first order rate constant (k) were slightly influenced by the initial concentration of NPs. The k value changed from 0.0202 ± 0.004 to 0.0456 ± 0.0023 min^-1 with an initial concentration range between 0.1 gL^-1 and 0.5 gL^-1 of NPs. The apparent activation energy for dechlorination was 17.712 kJmol^-1 in a temperature ranging from 35°C to 75°C. The reduction rate and extent of dechlorination were remarkably under the effect of higher temperature. Dehalogenation order of PCBs indicate that in high chlorinated biphenyls the chlorine situated at the following discipline Para(P)P(para)P_(higher) ortho(CP)_(lower) (meta)M have slightly more reactivity compared with PP_ (lower)CP_(higher) M > P_ CP_M > -_CP_M.